Direct-acting solenoid valve: Principle: power, electromagnetic coil generates electromagnetic force the closure of parts brought from the seat, the valve opens; power, the electromagnetic force disappears, spring to close the pressure in the valve seat, valve The door is closed. Characteristics: in vacuum, negative pressure, zero pressure can work, but the path is generally not more than 25mm.
Step-by-step direct-acting solenoid valves: Principles: It is a direct-acting and pilot - a combination of principle, when no pressure difference between inlet and outlet, the power, the electromagnetic force directly to the pilot valve and main valve to turn off parts in turn lift the valve opens. When the inlet and outlet reaches the start pressure, electricity, electromagnetic force pilot valve, main valve cavity pressure rise on chamber pressure drop, which use differential pressure to the main valve is pushed upwards; power failure, the pilot valve with a spring force or medium pressure to promote off, move down, so that the valve is closed. Features: * action also in the zero pressure or vacuum, high pressure, but the power is larger, the requirements must be mounted horizontally.
Pilot solenoid valve: Principle: power, electromagnetic force pilot hole open on the chamber pressure fell rapidly, close the pieces around the formation of low and high differential pressure, fluid pressure to promote off pieces to move up, the valve opens; energized, the spring force to the pilot hole Close the inlet pressure through the bypass hole quickly chamber off valve formed around a high pressure differential, the fluid pressure to promote the closure of parts moving down, close the valve. Features: higher maximum fluid pressure range can be freely installed (to be customized) but must meet the fluid pressure conditions. Solenoid valve from the valve structure and materials of different and the difference principle, be divided into six branch subclasses: straight diaphragm structure, step straight diaphragm structure, the pilot diaphragm structure, direct acting piston structure, step-by-step direct acting piston structure, the pilot piston structure.
Sunday, March 25, 2012
The cord set is made up of an elongated electric cord containing at least two flexible wires
The end of the electric cord connected to the electric tool is typically provided with a molded strain relief flexible body attached to the outer insulator of the electric cord and mechanically connected to the electric tool housing. Electrical tools are conventionally provided with a power cord set made up of an elongated electric cord having an electric plug at one end and the opposite end mechanically and electrically connected to the electric tool. The flexible body of the strain relief prevents the wires within the electrical cord from being broken as a result of being repeatedly bent in a small radius.
The cord set is made up of an elongated electric cord containing at least two flexible wires, an electric plug affixed to one end of the electric cord and a strain relief connector assembly affixed to the other end of the electric cord. The strain relief connector assembly is provided with an elongated flexible body extending about a length of the electric cord adjacent the end for mechanically attaching to and projecting into the electric tool housing.
The length and the end treatment of the wire leads of the power cord set varies depending upon the application, therefore, it is quite common for a power tool manufacturer to inventory dozens of different power cord sets. While power cord sets may vary somewhat due to the desired cord length, the primary distinction between varying stock keeping units (SKU's) is the length of the wire leads extending and the type of electrical connector formed on the wire end.
The number of SKU's for cord sets is not only a problem at the time of manufacturing due to the inventory requirements for each of the cord sets, but it remains a problem throughout the product's life since replacement cord sets have to be maintained in product service centers because cord sets are a rather frequent replacement item.
The power cord set of the present invention is provided for use with any one of a plurality of electric tools that have a housing, an electric powered implement oriented within the housing.
The strain relief-connector assembly is further provided with an electrical connector electrically connected to the at least two wires in the electric cord with the electrical connector projecting into the tool housing. The electric powered implement is provided with an internal pair of wires having a pair of connectors for cooperation with the strain relief connector assembly.
The cord set is made up of an elongated electric cord containing at least two flexible wires, an electric plug affixed to one end of the electric cord and a strain relief connector assembly affixed to the other end of the electric cord. The strain relief connector assembly is provided with an elongated flexible body extending about a length of the electric cord adjacent the end for mechanically attaching to and projecting into the electric tool housing.
The length and the end treatment of the wire leads of the power cord set varies depending upon the application, therefore, it is quite common for a power tool manufacturer to inventory dozens of different power cord sets. While power cord sets may vary somewhat due to the desired cord length, the primary distinction between varying stock keeping units (SKU's) is the length of the wire leads extending and the type of electrical connector formed on the wire end.
The number of SKU's for cord sets is not only a problem at the time of manufacturing due to the inventory requirements for each of the cord sets, but it remains a problem throughout the product's life since replacement cord sets have to be maintained in product service centers because cord sets are a rather frequent replacement item.
The power cord set of the present invention is provided for use with any one of a plurality of electric tools that have a housing, an electric powered implement oriented within the housing.
The strain relief-connector assembly is further provided with an electrical connector electrically connected to the at least two wires in the electric cord with the electrical connector projecting into the tool housing. The electric powered implement is provided with an internal pair of wires having a pair of connectors for cooperation with the strain relief connector assembly.
Characteristics of the air compressor
Characteristics of the air compressor:By the motor directly drives the compressor, so that the crankshaft to produce rotary motion to drive the connecting rod so that the piston reciprocating motion, causing the cylinder volume change. Air due to pressure changes within the cylinder through the intake valve into the cylinder after the air filter (muffler), due to the narrowing of the cylinder volume in the compression stroke, the role of compressed air through the exhaust valve, the exhaust pipe, one-way valve (check valve) into the gas tank, and automatically shut down by the pressure switch control when the exhaust pressure to rated pressure of 0.7MPa. When the gas tank pressure down to 0.5 - 0.6MPa pressure switch automatically join the start.
Working pressure of the gas source should be about 20% higher than the maximum working pressure in the pneumatic system, to consider the loss along the way and partial loss of the gas pipeline. If some parts of the system pressure to low pressure relief valve to gas supply. Rated discharge pressure of the air compressor is divided into low voltage (0.7 ~ 1.0MPa), medium pressure (1.0 to 10MPa), high pressure (10 ~ 100MPa) and ultra-high pressure (100MPa or more) can be selected according to actual demand. Common use of pressure is generally 0.7-1.25 First, select the type of air compressor air compressor features. The pneumatic system pressure and flow two parameters to determine the air compressor output pressure pc and the inhalation flow rate qc, and ultimately select the air compressor models.
To make the air compressor to normal and reliable operation to ensure that the service life of the unit are required to develop a detailed maintenance plan, the implementation of fixed-man operation, regular maintenance, regular inspection and maintenance of air compressor to keep clean, no oil, no dirt.
Moisture in the air may condense in the oil and gas separation tank, especially in wet weather, when the exhaust temperature is lower than the air pressure dew point or shutdown cooling, there will be more condensed water precipitates. Oil contains too much moisture will cause the emulsification of lubricating oil, affecting the safe operation of the machine,
Each run of the air compressor 2000h for the removal of the cooling surface of dust, the need to purge the coolers on the fan bracket to the manhole cover open, with dust blowing air gun cooler purge until the cooling surface dust purged. Yet if the cooling surface dirt serious, difficult to clean, purge, and can to remove the cooler, pour the oil cooler and four import and export closed to prevent dirt from entering, and then use compressed air to blow dust or water on both sides of rinse, and finally drying the surface of the water stains. Back in place.
Working pressure of the gas source should be about 20% higher than the maximum working pressure in the pneumatic system, to consider the loss along the way and partial loss of the gas pipeline. If some parts of the system pressure to low pressure relief valve to gas supply. Rated discharge pressure of the air compressor is divided into low voltage (0.7 ~ 1.0MPa), medium pressure (1.0 to 10MPa), high pressure (10 ~ 100MPa) and ultra-high pressure (100MPa or more) can be selected according to actual demand. Common use of pressure is generally 0.7-1.25 First, select the type of air compressor air compressor features. The pneumatic system pressure and flow two parameters to determine the air compressor output pressure pc and the inhalation flow rate qc, and ultimately select the air compressor models.
To make the air compressor to normal and reliable operation to ensure that the service life of the unit are required to develop a detailed maintenance plan, the implementation of fixed-man operation, regular maintenance, regular inspection and maintenance of air compressor to keep clean, no oil, no dirt.
Moisture in the air may condense in the oil and gas separation tank, especially in wet weather, when the exhaust temperature is lower than the air pressure dew point or shutdown cooling, there will be more condensed water precipitates. Oil contains too much moisture will cause the emulsification of lubricating oil, affecting the safe operation of the machine,
Each run of the air compressor 2000h for the removal of the cooling surface of dust, the need to purge the coolers on the fan bracket to the manhole cover open, with dust blowing air gun cooler purge until the cooling surface dust purged. Yet if the cooling surface dirt serious, difficult to clean, purge, and can to remove the cooler, pour the oil cooler and four import and export closed to prevent dirt from entering, and then use compressed air to blow dust or water on both sides of rinse, and finally drying the surface of the water stains. Back in place.
Wednesday, March 14, 2012
Products banned hazardous substance limit
In 1, RoHS directive banned hazardous substance limit,
Serial number material group allowable concentration
Cadmium and its compounds 1 is less than or equal to 100ppm
Lead and its compounds 2 is less than or equal to 1000ppm
Hexavalent chromium and its compounds 3 six 1000ppm
The 4 mercury and its compounds is less than or equal to 1000ppm
5 specific flame retardants PBBs = 1000ppm
6 specific flame retardants PBDEs = 1000ppm
In order to ensure that the company power cord products comply with the EU RoHS Directive requires strict control of raw materials, outsourcing parts on 6 kinds of
Harmful substances limits, foreign parts, purchased parts of harmful substances in the limit values are shown in Table 1, the company manufactured products containing harmful substances
Limit value should also be consistent with the above regulations.
Different target materials banned substances of the allowable concentration,
Object material objects prohibited substances permitted concentration
Plastic, rubber, thin film, paint, lead < 100ppm ( ICP high precision analysis method )
Ink, pigment, dye, copper wire,
Conventional metal parts
Cadmium < 5ppm ( ICP high precision analysis method )
Metal alloy lead
The following 0.35wt% -- Steel
The following 0.4wt% -- aluminum alloy
The following 4wt% -- copper alloy
( ICP high precision analysis method)
Lead free solder lead < 100ppm
High melting point solder lead content of more than 85% tin lead solder
Packaging material Pb ( lead) + Cd ( CD ) + Hg (Hg ) + Cr6 + ( chromium six ) < 100ppm ( ICP high precision analysis method)
The metal alloy material, lead-free solder and high melting point solder in lead content as specified in table 2.
4.3 in response to domestic and international the product of polycyclic aromatic hydrocarbon carcinogens ( PAHs ) Limited provisions, export products must be
Excluding the above provisions in material.
Limited value of polycyclic aromatic hydrocarbons
Serial number PAHs compounds limits PPM
1 Naphthalene naphthalene is less than or equal to 0.5
2 Acenaphthylene acenaphthylene is less than or equal to 0.5
3 Acenaphthene acenaphthene power supply cord acenaphthene is less than or equal to 0.5
4 Fluorene fluorene is less than or equal to 0.5
5 Phenanthrene Fe = 0.5
6 Anthracene anthracene is less than or equal to 0.5
7 Fluoranthene fluoranthene is less than or equal to 0.5
8 Pyrene P < 0.5
9 Benzo ( a ) anthracene benzo ( a < 0.5 ).
10 Chrysene flexor = 0.5
11 Benzo ( b ) fluoranthene benzo ( b ) fluoranthene is less than or equal to 0.5
12 Benzo ( k ) fluoranthene benzo ( k ) fluoranthene is less than or equal to 0.5
13 Benzo ( a ) pyrene benzo ( a ) P = 0.5
14 Indeno ( 1, 2, 3-cd ) indinavir benzene (1, 2, 3-cd < 0.5 ) pyrene
15 Dibenzo ( a, H ) anthracene two benzo ( a, H = 0.5 ).
16 Benzo ( g, HI ) perylene benzo ( g, HI ) two rylene = 0.5
Serial number material group allowable concentration
Cadmium and its compounds 1 is less than or equal to 100ppm
Lead and its compounds 2 is less than or equal to 1000ppm
Hexavalent chromium and its compounds 3 six 1000ppm
The 4 mercury and its compounds is less than or equal to 1000ppm
5 specific flame retardants PBBs = 1000ppm
6 specific flame retardants PBDEs = 1000ppm
In order to ensure that the company power cord products comply with the EU RoHS Directive requires strict control of raw materials, outsourcing parts on 6 kinds of
Harmful substances limits, foreign parts, purchased parts of harmful substances in the limit values are shown in Table 1, the company manufactured products containing harmful substances
Limit value should also be consistent with the above regulations.
Different target materials banned substances of the allowable concentration,
Object material objects prohibited substances permitted concentration
Plastic, rubber, thin film, paint, lead < 100ppm ( ICP high precision analysis method )
Ink, pigment, dye, copper wire,
Conventional metal parts
Cadmium < 5ppm ( ICP high precision analysis method )
Metal alloy lead
The following 0.35wt% -- Steel
The following 0.4wt% -- aluminum alloy
The following 4wt% -- copper alloy
( ICP high precision analysis method)
Lead free solder lead < 100ppm
High melting point solder lead content of more than 85% tin lead solder
Packaging material Pb ( lead) + Cd ( CD ) + Hg (Hg ) + Cr6 + ( chromium six ) < 100ppm ( ICP high precision analysis method)
The metal alloy material, lead-free solder and high melting point solder in lead content as specified in table 2.
4.3 in response to domestic and international the product of polycyclic aromatic hydrocarbon carcinogens ( PAHs ) Limited provisions, export products must be
Excluding the above provisions in material.
Limited value of polycyclic aromatic hydrocarbons
Serial number PAHs compounds limits PPM
1 Naphthalene naphthalene is less than or equal to 0.5
2 Acenaphthylene acenaphthylene is less than or equal to 0.5
3 Acenaphthene acenaphthene power supply cord acenaphthene is less than or equal to 0.5
4 Fluorene fluorene is less than or equal to 0.5
5 Phenanthrene Fe = 0.5
6 Anthracene anthracene is less than or equal to 0.5
7 Fluoranthene fluoranthene is less than or equal to 0.5
8 Pyrene P < 0.5
9 Benzo ( a ) anthracene benzo ( a < 0.5 ).
10 Chrysene flexor = 0.5
11 Benzo ( b ) fluoranthene benzo ( b ) fluoranthene is less than or equal to 0.5
12 Benzo ( k ) fluoranthene benzo ( k ) fluoranthene is less than or equal to 0.5
13 Benzo ( a ) pyrene benzo ( a ) P = 0.5
14 Indeno ( 1, 2, 3-cd ) indinavir benzene (1, 2, 3-cd < 0.5 ) pyrene
15 Dibenzo ( a, H ) anthracene two benzo ( a, H = 0.5 ).
16 Benzo ( g, HI ) perylene benzo ( g, HI ) two rylene = 0.5
Thursday, March 10, 2011
Female coupling component for a quick coupling
The present invention relates to a structure of a female coupling component which is included in a quick coupling. The female coupling component contains a centrally extending component and a sealing sleeve capable of longitudinal displacementwith respect to this component. Quick couplings designed for low or high pressure may be mentioned as examples.
A large number of quick couplings are known and used in various applications. Such devices may be included as a valve body in a quick coupling. If the quick coupling is to be used in a vulnerable environment, it may incorporate a so-calledprotective cover to prevent impurities and foreign particles from entering into the coupling. Couplings of this kind can also incorporate a holder for balls or similar as a part of a locking device for the male and female components of the quickcoupling.
In the case of the type of quick coupling mentioned above, the need exists in various respects to be able to achieve a construction which affords flexibility in the production and assembly of the quick coupling as part of a rational manufacturingprocess. The construction shall be capable for this purpose of being so executed as to consist of easily interchangeable components which can be combined together to meet various standards with regard to, for example, thread dimensions and thread types.
The quick coupling shall also exhibit a design whereby the quick coupling functions can take place in an optimal fashion, with low connection forces and absence of leakage on changing over, etc.
The object of the present invention is to propose, amongst other things, a design of female coupling component which allows to eliminate the indicated problems. The above new female coupling component of the present invention includes asleeve-shaped bearing component for the centrally extending device and the sealing sleeve is accommodated in a recess intended for that purpose in the female coupling component. The device is supported in the bearing component through radially extendingelements, by means of which one or more fluid passageways are formed between the outside of the device and the inside of the bearing component, and that the bearing component carries a load-relieving device for any fluid forces which act on the sealingsleeve as part of the function of the quick coupling.
In one embodiment of the present invention two elements for supporting the centrally extending device shall be executed with the help of a disc-shaped unit which extends diametrically in the fluid passageway of the bearing component. The unitshould preferably exhibit an anchoring recess for the centrally extending device, which can be provided with a threaded end part via which the device can be screwed into in a corresponding recess of the unit. In order for the centrally extending deviceto exhibit a rigid attachment, the threaded end part is provided with radially extending supporting surfaces which interact with corresponding surfaces on the end edge of the unit.
The unit can be provided with limited penetration in the longitudinal direction of the female coupling componet and yet is still capable of providing its securing function for the centrally extending device. The unit serves in a preferredembodiment as an end stop for the degree of insertion of the sealing sleeve into the female coupling component. In order to achieve a suitable sealing function in the quick coupling, it is essential for the sealing sleeve to be allocated apre-determined degree of insertion into the female coupling component. This degree of insertion can be determined by means of the devices which support the end stops of the unit, and may be in the form of one or more pins extending from the unit. Suchpins would extend from the unit in the longitudinal sense of the female coupling component.
In one embodiment the elements are securely supported in the longitudinal direction of the female coupling component. The support is provided at one end of the bearing component, and the sealing sleeve is supported in and works inside the otherparts of the bearing component. The sealing sleeve projects outwards through the other end of the bearing component so as to interact with devices in the male coupling components on connecting together the male and female components of the quickcoupling.
In the event of the female coupling component incorporating holders for locking balls, the bearing component should preferably be supported in a similar holder. The sealing sleeve is able in this way to interact with a first return spring whichis in contact with the aforementioned element, and the bearing component constitutes a support for a second return spring for a protective cover which may be arranged in the female coupling components.
The load-relieving devices consist essentially of inward-projecting devices, preferably arranged at the free end of the bearing component. Corresponding load-relieving devices on the sealing sleeve can have the form of corresponding projectingdevices situated on those parts of the sealing sleeve which are situated inside the bearing components.
The bearing component is capable of being accommodated in a recess in the female coupling component and secured with the help of an internal recess in the ball race when this is assembled with a body component or corresponding component of thefemale component. The sealing sleeve and the radial elements (the unit) are so arranged in relation to the anchoring component as to be capable of being accommodated before the anchoring component is accommodated inside the recess.
The embodiments indicated above provide advantages, especially in conjunction with the manufacture and assembly of quick coupling components. These can be executed with different threads which are suitable for use in their respective areas ofapplication. The essential functions and properties of quick couplings of this kind can be retained in spite of the fact that the first-named functions are additional.
A large number of quick couplings are known and used in various applications. Such devices may be included as a valve body in a quick coupling. If the quick coupling is to be used in a vulnerable environment, it may incorporate a so-calledprotective cover to prevent impurities and foreign particles from entering into the coupling. Couplings of this kind can also incorporate a holder for balls or similar as a part of a locking device for the male and female components of the quickcoupling.
In the case of the type of quick coupling mentioned above, the need exists in various respects to be able to achieve a construction which affords flexibility in the production and assembly of the quick coupling as part of a rational manufacturingprocess. The construction shall be capable for this purpose of being so executed as to consist of easily interchangeable components which can be combined together to meet various standards with regard to, for example, thread dimensions and thread types.
The quick coupling shall also exhibit a design whereby the quick coupling functions can take place in an optimal fashion, with low connection forces and absence of leakage on changing over, etc.
The object of the present invention is to propose, amongst other things, a design of female coupling component which allows to eliminate the indicated problems. The above new female coupling component of the present invention includes asleeve-shaped bearing component for the centrally extending device and the sealing sleeve is accommodated in a recess intended for that purpose in the female coupling component. The device is supported in the bearing component through radially extendingelements, by means of which one or more fluid passageways are formed between the outside of the device and the inside of the bearing component, and that the bearing component carries a load-relieving device for any fluid forces which act on the sealingsleeve as part of the function of the quick coupling.
In one embodiment of the present invention two elements for supporting the centrally extending device shall be executed with the help of a disc-shaped unit which extends diametrically in the fluid passageway of the bearing component. The unitshould preferably exhibit an anchoring recess for the centrally extending device, which can be provided with a threaded end part via which the device can be screwed into in a corresponding recess of the unit. In order for the centrally extending deviceto exhibit a rigid attachment, the threaded end part is provided with radially extending supporting surfaces which interact with corresponding surfaces on the end edge of the unit.
The unit can be provided with limited penetration in the longitudinal direction of the female coupling componet and yet is still capable of providing its securing function for the centrally extending device. The unit serves in a preferredembodiment as an end stop for the degree of insertion of the sealing sleeve into the female coupling component. In order to achieve a suitable sealing function in the quick coupling, it is essential for the sealing sleeve to be allocated apre-determined degree of insertion into the female coupling component. This degree of insertion can be determined by means of the devices which support the end stops of the unit, and may be in the form of one or more pins extending from the unit. Suchpins would extend from the unit in the longitudinal sense of the female coupling component.
In one embodiment the elements are securely supported in the longitudinal direction of the female coupling component. The support is provided at one end of the bearing component, and the sealing sleeve is supported in and works inside the otherparts of the bearing component. The sealing sleeve projects outwards through the other end of the bearing component so as to interact with devices in the male coupling components on connecting together the male and female components of the quickcoupling.
In the event of the female coupling component incorporating holders for locking balls, the bearing component should preferably be supported in a similar holder. The sealing sleeve is able in this way to interact with a first return spring whichis in contact with the aforementioned element, and the bearing component constitutes a support for a second return spring for a protective cover which may be arranged in the female coupling components.
The load-relieving devices consist essentially of inward-projecting devices, preferably arranged at the free end of the bearing component. Corresponding load-relieving devices on the sealing sleeve can have the form of corresponding projectingdevices situated on those parts of the sealing sleeve which are situated inside the bearing components.
The bearing component is capable of being accommodated in a recess in the female coupling component and secured with the help of an internal recess in the ball race when this is assembled with a body component or corresponding component of thefemale component. The sealing sleeve and the radial elements (the unit) are so arranged in relation to the anchoring component as to be capable of being accommodated before the anchoring component is accommodated inside the recess.
The embodiments indicated above provide advantages, especially in conjunction with the manufacture and assembly of quick coupling components. These can be executed with different threads which are suitable for use in their respective areas ofapplication. The essential functions and properties of quick couplings of this kind can be retained in spite of the fact that the first-named functions are additional.
Revolvable quick coupling
The present invention relates to quick couplings and relates more particularly to a revolvable quick coupling for connecting an air pipe from an air compressor to a pneumatic tool, which automatically seal off the air passage therein once a pneumatic tool is detached and, which follows a pneumatic tool to rotate on a second air pipe connector without twisting the air pipe from of the connected air compressor.
Various quick connectors have been known and used in connecting air compressors to pneumatic tools. However, the known quick connectors are not satisfactory in use because neither one of them can be rotated by a pneumatic tool. If a quick connector is rotated by a pneumatic tool, the air pipe which is connected thereto will be twisted and damaged causing air leakage problem. The present invention has been accomplished to eliminate this problem.
According to the present invention, there is provided a revolvable quick coupling comprised of a first air pipe connector revolvably secured to an intermediate connecting member by a ball bearing means and connected to an air output pipe of an air compressor, a second air pipe connector secured to the intermediate connecting member by a front socket, a retainer, an inner socket, a seal ring, a stepped metal element and a spring means for connecting to an air input pipe of a pneumatic tool, wherein pressing on the retainer causes the second air pipe connector to disconnect from the front socket and simultaneously causes the seal ring to seal the air passage inside the coupling; rotating the pneumatic tool causes the second air pipe connector to rotate on the first air pipe connector without twisting the air output pipe of the air compressor.
Various quick connectors have been known and used in connecting air compressors to pneumatic tools. However, the known quick connectors are not satisfactory in use because neither one of them can be rotated by a pneumatic tool. If a quick connector is rotated by a pneumatic tool, the air pipe which is connected thereto will be twisted and damaged causing air leakage problem. The present invention has been accomplished to eliminate this problem.
According to the present invention, there is provided a revolvable quick coupling comprised of a first air pipe connector revolvably secured to an intermediate connecting member by a ball bearing means and connected to an air output pipe of an air compressor, a second air pipe connector secured to the intermediate connecting member by a front socket, a retainer, an inner socket, a seal ring, a stepped metal element and a spring means for connecting to an air input pipe of a pneumatic tool, wherein pressing on the retainer causes the second air pipe connector to disconnect from the front socket and simultaneously causes the seal ring to seal the air passage inside the coupling; rotating the pneumatic tool causes the second air pipe connector to rotate on the first air pipe connector without twisting the air output pipe of the air compressor.
Device for producing quick couplings for dental prostheses
Removable dental prostheses are currently known which have appropriate couplings for rapid anchoring to the remaining dental structures. Conventional couplings often have grip problems and tend to slacken in the course of time, creating many problems to their users. Furthermore, said couplings are often relatively expensive, so that their replacement is scarcely convenient.
In order to obviate this problem, a quick coupling for dental prostheses has been proposed which is capable of assuring durable grip, as described in U.S. Pat. No. 5,030,094.
Said quick coupling for dental prostheses essentially comprises at least one spherical male element, which is intended to be integrated in a fixed part of the prosthesis, and a female element, whose shape is complementary to the shape of said male element, correspondingly provided on a removable part of the prosthesis. The female element, which is intended to couple to said male element, is shaped like a cap made of plastic material which is intended to be accommodated and stably retained in the removable part of the prosthesis.
Conveniently, the seat for said plastic cap, in the removable part of the prosthesis, is defined in a metallic piece which is intended to be monolithic with said removable part. Said metallic piece is preferably obtained by lost-wax casting starting from a refractory-lined model of the arch to be reconstructed.
The male element, which is monolithic with the fixed part of the prosthesis, is instead obtained by casting starting from a corresponding prefabricated male element made of calcinable plastic material.
In practice, in order to produce the quick couplings, a metallic element, having the same outside contour as said plastic cap, is applied on the male element. The impression of the unit thus formed is then made, and a model made of refractory material is then produced and subsequently modeled in wax according to the required shape of said metallic piece which is intended to define the seat of the plastic cap. The metallic portion of the removable part of the prosthesis is finally produced by lost-wax casting.
This aim and this object are both achieved, according to the invention, by the present device for producing quick couplings for dental prostheses, of the type which comprises at least one substantially spherical male element, which is intended to be monolithically integrated with a fixed part of said prosthesis, and a female element, whose inner shape is complementary to the shape of said male element, which is correspondingly provided on a removable part of said prosthesis, characterized in that it comprises a pair of auxiliary bars, made of a calcinable plastic material, which are connectable one on top of the other, and which cooperate so as to define at least one compartment whose shape is complementary to the outside shape of a cap which defines said female element, said bars being arrangeable about said male element in order to obtain a model of a metallic piece of said removable part of the prosthesis to be produced by lost-wax casting.
The described device allows, in summary, to provide in a simple manner quick couplings for dental prostheses, with an evident saving in time and material. In fact it is not necessary, in this case, to produce a refractory duplicate of the piece to be modeled, but the work is done on the elements which constitute the fixed part of the prosthesis, which are obtained beforehand in a conventional manner, using appropriate portions of the calcinable auxiliary bars.
In order to obviate this problem, a quick coupling for dental prostheses has been proposed which is capable of assuring durable grip, as described in U.S. Pat. No. 5,030,094.
Said quick coupling for dental prostheses essentially comprises at least one spherical male element, which is intended to be integrated in a fixed part of the prosthesis, and a female element, whose shape is complementary to the shape of said male element, correspondingly provided on a removable part of the prosthesis. The female element, which is intended to couple to said male element, is shaped like a cap made of plastic material which is intended to be accommodated and stably retained in the removable part of the prosthesis.
Conveniently, the seat for said plastic cap, in the removable part of the prosthesis, is defined in a metallic piece which is intended to be monolithic with said removable part. Said metallic piece is preferably obtained by lost-wax casting starting from a refractory-lined model of the arch to be reconstructed.
The male element, which is monolithic with the fixed part of the prosthesis, is instead obtained by casting starting from a corresponding prefabricated male element made of calcinable plastic material.
In practice, in order to produce the quick couplings, a metallic element, having the same outside contour as said plastic cap, is applied on the male element. The impression of the unit thus formed is then made, and a model made of refractory material is then produced and subsequently modeled in wax according to the required shape of said metallic piece which is intended to define the seat of the plastic cap. The metallic portion of the removable part of the prosthesis is finally produced by lost-wax casting.
This aim and this object are both achieved, according to the invention, by the present device for producing quick couplings for dental prostheses, of the type which comprises at least one substantially spherical male element, which is intended to be monolithically integrated with a fixed part of said prosthesis, and a female element, whose inner shape is complementary to the shape of said male element, which is correspondingly provided on a removable part of said prosthesis, characterized in that it comprises a pair of auxiliary bars, made of a calcinable plastic material, which are connectable one on top of the other, and which cooperate so as to define at least one compartment whose shape is complementary to the outside shape of a cap which defines said female element, said bars being arrangeable about said male element in order to obtain a model of a metallic piece of said removable part of the prosthesis to be produced by lost-wax casting.
The described device allows, in summary, to provide in a simple manner quick couplings for dental prostheses, with an evident saving in time and material. In fact it is not necessary, in this case, to produce a refractory duplicate of the piece to be modeled, but the work is done on the elements which constitute the fixed part of the prosthesis, which are obtained beforehand in a conventional manner, using appropriate portions of the calcinable auxiliary bars.
Quick coupling component with pressure reduction member
The present invention relates to a quick coupling component including one or more valve members for opening and closing a main flow, and a pressure reduction member arranged of a pressure reduction channel in at least one valve member. The pressure reduction member includes a first shut-off element arranged in the pressure reduction channel and is provided with a spherical surface. The shut-off element, in a closed position for the pressure reduction channel the shut-off element, bears against a seat. In an open position for the channel, is lifted from the seat by an activation member counter to the action of a spring function.
A pressure reduction function in quick coupling is already known, and in this respect reference can be made to the U.S. Pat. No. 4,564,042 and 5,159,955. In such a coupling the pressure reduction function can be included in one or both of the coupling components. The pressure reduction function includes a shut-off element in the form of a ball that is acted upon, counter to the action of a spring, in order to lift it from its seat. Media can then flow past the shut-off element. The passing flow causes the pressure, acting counter to the coupling force of the coupling components, to be released. In this way coupling of the coupling components is considerably facilitated. Depending on how the pressure conditions appear before coupling, in the coupling arrangement in question the coupling component concerned or both coupling components is/are provided with a pressure reduction function.
There are great problems involved in achieving an appropriate pressure elimination function. The shut-off element must be completely sealed against the seat surface in question. Otherwise, media can leak past in the closure position of the pressure elimination function media can also leak out, for example, to the outer surface of the coupling component concerned. This surface is thus soiled with media, for example hydraulic oil. Such a soiling cannot normally be accepted, accordingly it is currently demanded of quick couplings that they should be able to function in or create a leakproof environment. In this connection, it should be mentioned that even the leaking of what are, relatively speaking very small quantities of media presents problems. The aim of the invention, among other things is to solve, these problems.
The said above described problems are aggravated by the fact that the quick coupling should be able to be coupled against even relatively high pressures, for example pressures of 300 bar or more, which sets even higher demands on the sealing function in the pressure reduction function. The invention solves this problem too.
Quick couplings are generally manufactured in relatively long series. In addition, different components can be manufactured by different manufacturers. Also an assembly can be carried out by yet another manufacturer, etc. Furthermore, the different components manufactured in this way must, on the one hand, exhibit great accuracy of manufacture and, on the other hand be able to function together in the finally assembled state of the couplings. This necessitates the independence of pressure elimination function in relation to the manufacturing circumstances. The invention solves this problem too.
It must be possible for the quick coupling to function for relatively long periods of time without the need for frequent servicing and replacement of vital components in the coupling. Also it should be possible for a quick coupling to be subjected to a very large number, for example 100,000, of couplings and decouplings. This also places demands on the pressure elimination function, which should come into operation in all coupling instances. The present invention solves this problem too.
The quick coupling should be able to operate at different pressures and pressure conditions with increasing pressures. In addition, it should be possible for a quick coupling to be used in any chosen situation within a wide appropriate coupling range. The pressure reduction function means must be able to function for all the connection possibilities which are conceivable for the coupling in question. The invention solves this problem.
Quick coupling is often part of a product range which is subject to pricing pressures, with the result that it must be possible to use efficient, automated and/or cost-effective manufacturing methods. This invention solves this problem too.
The feature which can principally be regarded as characterizing a quick coupling component according to the invention is that the seat is designed with a seat surface that corresponds to parts of the spherical surface of the shut-off element. The seat surface has a degree of fineness that to a great extent corresponds to the degree of fineness of a shut-off element. To a great extent here means that the degree of fineness of the seat surface should amount to 50-100%, preferably 75% or more, of the degree of fineness of a shut-off element that is used in this connection and has a hardness that substantially exceeds the hardness of the seat material, for example exceeds the hardness of the seat material by 1-4 times. A further characteristic of the invention is that an elasticity inherent to the material of the seat and/or the element contributes to the sealing function of the spherical element against the seat in the said closed position.
A pressure reduction function in quick coupling is already known, and in this respect reference can be made to the U.S. Pat. No. 4,564,042 and 5,159,955. In such a coupling the pressure reduction function can be included in one or both of the coupling components. The pressure reduction function includes a shut-off element in the form of a ball that is acted upon, counter to the action of a spring, in order to lift it from its seat. Media can then flow past the shut-off element. The passing flow causes the pressure, acting counter to the coupling force of the coupling components, to be released. In this way coupling of the coupling components is considerably facilitated. Depending on how the pressure conditions appear before coupling, in the coupling arrangement in question the coupling component concerned or both coupling components is/are provided with a pressure reduction function.
There are great problems involved in achieving an appropriate pressure elimination function. The shut-off element must be completely sealed against the seat surface in question. Otherwise, media can leak past in the closure position of the pressure elimination function media can also leak out, for example, to the outer surface of the coupling component concerned. This surface is thus soiled with media, for example hydraulic oil. Such a soiling cannot normally be accepted, accordingly it is currently demanded of quick couplings that they should be able to function in or create a leakproof environment. In this connection, it should be mentioned that even the leaking of what are, relatively speaking very small quantities of media presents problems. The aim of the invention, among other things is to solve, these problems.
The said above described problems are aggravated by the fact that the quick coupling should be able to be coupled against even relatively high pressures, for example pressures of 300 bar or more, which sets even higher demands on the sealing function in the pressure reduction function. The invention solves this problem too.
Quick couplings are generally manufactured in relatively long series. In addition, different components can be manufactured by different manufacturers. Also an assembly can be carried out by yet another manufacturer, etc. Furthermore, the different components manufactured in this way must, on the one hand, exhibit great accuracy of manufacture and, on the other hand be able to function together in the finally assembled state of the couplings. This necessitates the independence of pressure elimination function in relation to the manufacturing circumstances. The invention solves this problem too.
It must be possible for the quick coupling to function for relatively long periods of time without the need for frequent servicing and replacement of vital components in the coupling. Also it should be possible for a quick coupling to be subjected to a very large number, for example 100,000, of couplings and decouplings. This also places demands on the pressure elimination function, which should come into operation in all coupling instances. The present invention solves this problem too.
The quick coupling should be able to operate at different pressures and pressure conditions with increasing pressures. In addition, it should be possible for a quick coupling to be used in any chosen situation within a wide appropriate coupling range. The pressure reduction function means must be able to function for all the connection possibilities which are conceivable for the coupling in question. The invention solves this problem.
Quick coupling is often part of a product range which is subject to pricing pressures, with the result that it must be possible to use efficient, automated and/or cost-effective manufacturing methods. This invention solves this problem too.
The feature which can principally be regarded as characterizing a quick coupling component according to the invention is that the seat is designed with a seat surface that corresponds to parts of the spherical surface of the shut-off element. The seat surface has a degree of fineness that to a great extent corresponds to the degree of fineness of a shut-off element. To a great extent here means that the degree of fineness of the seat surface should amount to 50-100%, preferably 75% or more, of the degree of fineness of a shut-off element that is used in this connection and has a hardness that substantially exceeds the hardness of the seat material, for example exceeds the hardness of the seat material by 1-4 times. A further characteristic of the invention is that an elasticity inherent to the material of the seat and/or the element contributes to the sealing function of the spherical element against the seat in the said closed position.
Pneumatic polishing head for CMP apparatus
CMP apparatus is used primarily for polishing the front face or device side of a semiconductor wafer during the fabrication of semiconductor devices on the wafer. A wafer is planarized or smoothed one or more times during the fabrication process in order for the top surface of the wafer to be as flat as possible. A wafer is polished by being placed on a carrier and pressed face down onto a polishing pad covered with a slurry of colloidal silica or alumina in de-ionized water.
A polishing pad is typically constructed in two layers overlying a platen with the less resilient layer as the outer layer of the pad. The layers are typically made of polyurethane and may include a filler for controlling the dimensional stability of the layers. A polishing pad is usually several times the diameter of a wafer and the wafer is kept off center on the pad to prevent polishing a non-planar surface onto the wafer. The wafer is rotated to prevent polishing a taper into the wafer. Although the axis of rotation of the wafer and the axis of rotation of the pad are not collinear, the axes must be parallel.
The platens used for a polishing pad and for a polishing head are carefully machined to produce optically flat, parallel surfaces. The resilient layers on a polishing pad are assumed to provide a uniform pressure on a wafer. It is believed that this assumption is in error and one aspect of the invention addresses the problem of distortion in the polishing pad.
Polishing heads must meet somewhat conflicting requirements for use in CMP apparatus. The wafer must be securely held but not damaged or contaminated. Polishing heads of the prior art typically use a wax-like material to attach the wafer temporarily to the carrier. The wax must be completely removable and must not affect the silicon to which it is attached. The polishing head cannot be so rigid that the wafer is chipped or damaged when the wafer engages the polishing pad or the head.
Gill, Jr. et al. U.S. Pat. No. 4,141,180 discloses a polishing head attached to a vertical shaft by a ball and socket joint to permit limited movement of the head to accommodate variations in the thickness of a wafer. The wafer carrier is covered with a felt-like material and the wafer is held against the nap surface by a vacuum coupled to the back of the wafer through a plurality of holes in the carrier. The polishing head includes a plastic ring encircling the wafer to locate the wafer radially with respect to the vertical shaft.
Shendon et al. U.S. Pat. No. 5,205,082 discloses a polishing head including a flexible diaphragm attached to a wafer carrier and to a retaining ring. Air pressure on one side of the diaphragm is above ambient pressure and air pressure on the wafer side of the diaphragm is at ambient pressure. The pressure on a wafer can be non-uniform due to forces from deflection of the diaphragm itself. Vertical motion of the carrier is limited by a flange engaging an adjustment bolt, which must be loosened to lower the carrier. A Cwasher is described for facilitating this adjustment.
The retaining ring surrounding a wafer in a polishing head of the prior art has an inside diameter slightly larger than the diameter of the wafer and there is always a slight gap between the wafer and the ring. Whether the ring presses against the resilient polishing pad or not, there is inevitably an annular region about the periphery of the wafer where the polishing is not uniform, known in the art as ;edge exclusion. Edge exclusion in the prior art is typically 5-10 mm. wide and reduces the area of the wafer from which good die can be obtained.
It is known in the art that uniformity in wafer polishing is a function of pressure, velocity, and the concentration of chemicals. Edge exclusion is caused, in part, by non-uniform pressure on a wafer. The prior art attempts to solve the problem by contacting the polishing pad with the retaining ring, e.g. as disclosed in the Shendon et al. patent, but the problem remains.
Another aspect of the problem of uniformity is the distribution of the slurry. As a wafer is polished, chemical by-products locally change the composition, pH, particle size, and uniformity of the slurry. In the prior art, this problem was addressed by thoroughly mixing the slurry and by controlling the rate of flow to the polishing pad; specifically, by providing a sufficient flow to prevent large, local changes in composition, particle size, or pH. Even so, edge exclusion remains a problem.
The foregoing objects are achieved by this invention in which a polishing head includes a carrier plate having concentric, integral, cylindrical walls, an annular piston fitting within the outer of the cylindrical walls and a second piston fitting within the inner cylindrical wall and engaging the annular piston. Each piston defines a chamber with the carrier plate and the chambers are isolated from each other by a seal. Pneumatic fittings supply air or vacuum to each chamber. The second piston includes a cylindrical side wall and an integral bottom plate. The bottom plate is thicker in the center than at the side wall and the underside of the plate is covered with a wafer adhering layer. A retaining ring is attached to the lower edge of the annular piston. In accordance with another aspect of the invention, the retaining ring includes a peripheral groove for separating an outwardly extending flange from the main body of the ring. In accordance with a further aspect of the invention, the underside of the retaining ring includes one or more spiral grooves for circulating slurry about a wafer during polishing.
A polishing pad is typically constructed in two layers overlying a platen with the less resilient layer as the outer layer of the pad. The layers are typically made of polyurethane and may include a filler for controlling the dimensional stability of the layers. A polishing pad is usually several times the diameter of a wafer and the wafer is kept off center on the pad to prevent polishing a non-planar surface onto the wafer. The wafer is rotated to prevent polishing a taper into the wafer. Although the axis of rotation of the wafer and the axis of rotation of the pad are not collinear, the axes must be parallel.
The platens used for a polishing pad and for a polishing head are carefully machined to produce optically flat, parallel surfaces. The resilient layers on a polishing pad are assumed to provide a uniform pressure on a wafer. It is believed that this assumption is in error and one aspect of the invention addresses the problem of distortion in the polishing pad.
Polishing heads must meet somewhat conflicting requirements for use in CMP apparatus. The wafer must be securely held but not damaged or contaminated. Polishing heads of the prior art typically use a wax-like material to attach the wafer temporarily to the carrier. The wax must be completely removable and must not affect the silicon to which it is attached. The polishing head cannot be so rigid that the wafer is chipped or damaged when the wafer engages the polishing pad or the head.
Gill, Jr. et al. U.S. Pat. No. 4,141,180 discloses a polishing head attached to a vertical shaft by a ball and socket joint to permit limited movement of the head to accommodate variations in the thickness of a wafer. The wafer carrier is covered with a felt-like material and the wafer is held against the nap surface by a vacuum coupled to the back of the wafer through a plurality of holes in the carrier. The polishing head includes a plastic ring encircling the wafer to locate the wafer radially with respect to the vertical shaft.
Shendon et al. U.S. Pat. No. 5,205,082 discloses a polishing head including a flexible diaphragm attached to a wafer carrier and to a retaining ring. Air pressure on one side of the diaphragm is above ambient pressure and air pressure on the wafer side of the diaphragm is at ambient pressure. The pressure on a wafer can be non-uniform due to forces from deflection of the diaphragm itself. Vertical motion of the carrier is limited by a flange engaging an adjustment bolt, which must be loosened to lower the carrier. A Cwasher is described for facilitating this adjustment.
The retaining ring surrounding a wafer in a polishing head of the prior art has an inside diameter slightly larger than the diameter of the wafer and there is always a slight gap between the wafer and the ring. Whether the ring presses against the resilient polishing pad or not, there is inevitably an annular region about the periphery of the wafer where the polishing is not uniform, known in the art as ;edge exclusion. Edge exclusion in the prior art is typically 5-10 mm. wide and reduces the area of the wafer from which good die can be obtained.
It is known in the art that uniformity in wafer polishing is a function of pressure, velocity, and the concentration of chemicals. Edge exclusion is caused, in part, by non-uniform pressure on a wafer. The prior art attempts to solve the problem by contacting the polishing pad with the retaining ring, e.g. as disclosed in the Shendon et al. patent, but the problem remains.
Another aspect of the problem of uniformity is the distribution of the slurry. As a wafer is polished, chemical by-products locally change the composition, pH, particle size, and uniformity of the slurry. In the prior art, this problem was addressed by thoroughly mixing the slurry and by controlling the rate of flow to the polishing pad; specifically, by providing a sufficient flow to prevent large, local changes in composition, particle size, or pH. Even so, edge exclusion remains a problem.
The foregoing objects are achieved by this invention in which a polishing head includes a carrier plate having concentric, integral, cylindrical walls, an annular piston fitting within the outer of the cylindrical walls and a second piston fitting within the inner cylindrical wall and engaging the annular piston. Each piston defines a chamber with the carrier plate and the chambers are isolated from each other by a seal. Pneumatic fittings supply air or vacuum to each chamber. The second piston includes a cylindrical side wall and an integral bottom plate. The bottom plate is thicker in the center than at the side wall and the underside of the plate is covered with a wafer adhering layer. A retaining ring is attached to the lower edge of the annular piston. In accordance with another aspect of the invention, the retaining ring includes a peripheral groove for separating an outwardly extending flange from the main body of the ring. In accordance with a further aspect of the invention, the underside of the retaining ring includes one or more spiral grooves for circulating slurry about a wafer during polishing.
Pneumatic Fittings Filter Replacement Routines
Do you know how effective your pneumatic fittings filter is or when to change it? Right now gauging system performance is a hit or miss activity. Use of a NeSSI-bus-enabled differential-pressure or moisture-breakthrough sensor (common in continuous emission monitoring systems) would give hard data.
It would allow us to validate filter performance and move from preventive to predictive maintenance. Automation of the filter also will lead to adoption of more-intelligent filtration devices that predict life span and initiate self-cleaning routines.
Using the DCS to control analytical systems. The advent of low-cost miniature computing and control devices will enable sampling-system control functions to become distributed and local to the sample system. Simple programmable control applets will dominate, be interchangeable across platforms and available from third parties. Sensors and actuators associated with auxiliary systems such as carrier-gas generators, heat tracers, conditioners (vaporizing regulators, sample recovery systems, etc.) can be integrated on the NeSSI-bus. With these sensors we can monitor and apply set points to our auxiliary process-analytical support system. The process analytical SAM can significantly extend limited control functionality previously provided by the DCS and various controllers.
Thermostats for temperature control. We can replace thermostats with PID control loops. We already are doing this using commercially available smart heaters. Advantages include the ability to maintain higher temperatures thanks to tighter control of the heater. Although an explosion-proof heater can't run on intrinsically safe power, its temperature and set-point signals can be integrated into the NeSSI-bus. Reliability will be enhanced by being able to better monitor and control critical dew points and bubble points of the process sample.
Valve Control Module and Transmitter: Module (left) comes with a lockout to prevent actuation of multiple valves at the same time. Photo courtesy of Swagelok.
Gas cylinders for calibration and validation. More-precise flow and temperature control in a sample system affords the opportunity to opt for more permeation generators to calibrate and validate analytical sensors. Today we use bulky gas cylinders to do this chore. It would be a tremendous advantage from an installation and operational point of view to eliminate calibration cylinders when the components needed are available as permeation sources.
Maintenance resources and routine rounds.NeSSI can eliminate the need for continual checks and adjustments. The new generation of smart analyzers such as gas chromatographs will have visualization built into the sample system as part of their local human machine interface (HMI) and remote workstations, helping analyzer technicians properly troubleshoot. Indeed, troubleshooting will become more of a science than an art. Portable zone-2-rated laptop computers or PDAs can effectively serve as the new "adjustable wrench" for the technician.
Block and vent valves for gas chromatograph sample introduction. Typically to ensure constant molecular volume we reference the sample pressure to atmosphere using a block-and-vent-valve arrangement prior to injecting a sample into a gas chromatograph. The ability to use an absolute pressure sensor will allow more-precise measurement and better control without the need for block-and-vent hardware. Of course, this would require the sample system to communicate with the gas chromatograph.
System-centric health monitoring. Sensors and networking will enable expansion of monitoring to all elements of an analytical system. It will permit overall analytical system performance to appear in the control room as a traffic light status signal that tells the operator whether the complete process analytical system is good, bad or is still good but will soon require maintenance. This will improve the operator's confidence in the performance of the analyzer system.
Bus systems undoubtedly will mature fairly quickly; many components including miniature flow meters, pressure sensors, smart heaters and both proportional and on/off automated valves either are available or will be in the next couple of years. Ability to purchase functional applets that could work across multiple analyzer systems will be truly revolutionary - they even may be fun to use. Today SAM functionality is embedded in more-complex analyzers such as gas chromatographs. Extending it to other analyzers demands a compact NeSSI-bus-enabled SAM.
Until that's available we'll struggle to bring standardization and simplicity to our discipline. Until then we'll continue to supply ad hoc and proprietary solutions that will work - but not support our general move to Generation III microanalytical and by-line installations. Our objective is to allow a microanalytical manufacturer to be able to plug into the mechanical and communication rails - and configure its devices sampling tasks using off-the-shelf applets. This architecture finally will enable the sampling and analytical measurement to go hand-in-hand as an integrated package.
The cost and pneumatic fittings technical effort to move to complete sample-system automation will be high. However end users will gain significant rewards including higher reliability and lower maintenance costs. It'll take a clear vision and concerted effort to change the game - but the horse is out of the barn and it's only a matter of time before we'll look back and wonder why we clung to our manual systems for so long. However, until that time comes we'll continue, out of sheer habit, to build steel copies of wooden bridges.
It would allow us to validate filter performance and move from preventive to predictive maintenance. Automation of the filter also will lead to adoption of more-intelligent filtration devices that predict life span and initiate self-cleaning routines.
Using the DCS to control analytical systems. The advent of low-cost miniature computing and control devices will enable sampling-system control functions to become distributed and local to the sample system. Simple programmable control applets will dominate, be interchangeable across platforms and available from third parties. Sensors and actuators associated with auxiliary systems such as carrier-gas generators, heat tracers, conditioners (vaporizing regulators, sample recovery systems, etc.) can be integrated on the NeSSI-bus. With these sensors we can monitor and apply set points to our auxiliary process-analytical support system. The process analytical SAM can significantly extend limited control functionality previously provided by the DCS and various controllers.
Thermostats for temperature control. We can replace thermostats with PID control loops. We already are doing this using commercially available smart heaters. Advantages include the ability to maintain higher temperatures thanks to tighter control of the heater. Although an explosion-proof heater can't run on intrinsically safe power, its temperature and set-point signals can be integrated into the NeSSI-bus. Reliability will be enhanced by being able to better monitor and control critical dew points and bubble points of the process sample.
Valve Control Module and Transmitter: Module (left) comes with a lockout to prevent actuation of multiple valves at the same time. Photo courtesy of Swagelok.
Gas cylinders for calibration and validation. More-precise flow and temperature control in a sample system affords the opportunity to opt for more permeation generators to calibrate and validate analytical sensors. Today we use bulky gas cylinders to do this chore. It would be a tremendous advantage from an installation and operational point of view to eliminate calibration cylinders when the components needed are available as permeation sources.
Maintenance resources and routine rounds.NeSSI can eliminate the need for continual checks and adjustments. The new generation of smart analyzers such as gas chromatographs will have visualization built into the sample system as part of their local human machine interface (HMI) and remote workstations, helping analyzer technicians properly troubleshoot. Indeed, troubleshooting will become more of a science than an art. Portable zone-2-rated laptop computers or PDAs can effectively serve as the new "adjustable wrench" for the technician.
Block and vent valves for gas chromatograph sample introduction. Typically to ensure constant molecular volume we reference the sample pressure to atmosphere using a block-and-vent-valve arrangement prior to injecting a sample into a gas chromatograph. The ability to use an absolute pressure sensor will allow more-precise measurement and better control without the need for block-and-vent hardware. Of course, this would require the sample system to communicate with the gas chromatograph.
System-centric health monitoring. Sensors and networking will enable expansion of monitoring to all elements of an analytical system. It will permit overall analytical system performance to appear in the control room as a traffic light status signal that tells the operator whether the complete process analytical system is good, bad or is still good but will soon require maintenance. This will improve the operator's confidence in the performance of the analyzer system.
Bus systems undoubtedly will mature fairly quickly; many components including miniature flow meters, pressure sensors, smart heaters and both proportional and on/off automated valves either are available or will be in the next couple of years. Ability to purchase functional applets that could work across multiple analyzer systems will be truly revolutionary - they even may be fun to use. Today SAM functionality is embedded in more-complex analyzers such as gas chromatographs. Extending it to other analyzers demands a compact NeSSI-bus-enabled SAM.
Until that's available we'll struggle to bring standardization and simplicity to our discipline. Until then we'll continue to supply ad hoc and proprietary solutions that will work - but not support our general move to Generation III microanalytical and by-line installations. Our objective is to allow a microanalytical manufacturer to be able to plug into the mechanical and communication rails - and configure its devices sampling tasks using off-the-shelf applets. This architecture finally will enable the sampling and analytical measurement to go hand-in-hand as an integrated package.
The cost and pneumatic fittings technical effort to move to complete sample-system automation will be high. However end users will gain significant rewards including higher reliability and lower maintenance costs. It'll take a clear vision and concerted effort to change the game - but the horse is out of the barn and it's only a matter of time before we'll look back and wonder why we clung to our manual systems for so long. However, until that time comes we'll continue, out of sheer habit, to build steel copies of wooden bridges.
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