Diaphragm valve and its manufacturing method

Abstract

To provide a diaphragm valve in which a part of a valve body brought into contact with a valve seat of a valve box is formed of a dissimilar material to improve flex life and mechanical strength, and a manufacturing method thereof.SOLUTION: A diaphragm valve 10 comprises a valve element 11 that contacts a valve seat 33 of a valve body 30 to close flow paths 31, 32, and a diaphragm 15 that supports the valve element so as to be displaceable in an axial direction. The valve element includes a seal part 12 that contacts the valve seat, and a valve body 13 linked to the diaphragm and supporting the seal part. The seal part is PFA, and the valve body and the diaphragm are PTFE or modified PTFE.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a diaphragm valve for use in semiconductor manufacturing equipment and the like to control the flow of raw material fluids, cleaning fluids, fuel fluids, etc., and to a method for manufacturing the same. [Background technology]

[0002] In various types of equipment for manufacturing, cleaning, assembly, etc. in the fields of electronics (e.g. semiconductors), medicine, biotechnology, etc., liquids such as raw material fluids, cleaning fluids, and fuel fluids are supplied and transported, and the flow of these liquids in the flow paths is controlled by diaphragm valves arranged in the valve box.

[0003] A diaphragm valve, as shown in Patent Document 1, for example, includes a valve body that contacts a valve seat of a valve box to close a flow path, and a diaphragm that supports the valve body so that it can be displaced in the axial direction. The diaphragm valve is connected to a drive mechanism that operates the valve body in the axial direction.

[0004] Diaphragm valves are required to be stable, non-reactive, and chemical resistant to the liquids flowing through the device, and are made of PTFE (polytetrafluoroethylene) or modified PTFE. Diaphragm valves are manufactured by cutting these materials. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 9-89131 Summary of the Invention [Problem to be solved by the invention]

[0006] PTFE and modified PTFE are materials with excellent flex life (resistance to repeated fatigue), but they do not have sufficient mechanical strength. As a result, the valve disc can be scraped off by repeated collisions with the valve seat, resulting in fine dust particles that can be mixed into the liquid.

[0007] Therefore, diaphragm valves are manufactured by cutting PFA (tetrafluoroethylene-perfluoroalkoxyethylene copolymer), which has stability, non-reactivity, and chemical resistance to liquids and has higher mechanical strength than PTFE or modified PTFE. However, PFA does not have the same durability as PTFE or modified PTFE because its flex life is inferior to that of PTFE or modified PTFE.

[0008] An object of the present invention is to provide a diaphragm valve and a manufacturing method thereof in which a portion of the valve body that abuts against the valve seat of the valve body is made of a different material, thereby enabling increased flexible life and mechanical strength. [Means for solving the problem]

[0009] The diaphragm valve of the present invention comprises: A diaphragm valve comprising a valve body that contacts a valve seat of a valve box to close a flow path, and a diaphragm that supports the valve body so that the valve body can be displaced in an axial direction, The valve element includes a seal portion that contacts the valve seat, and a valve body that is connected to the diaphragm and supports the seal portion, The sealing portion is made of PFA (tetrafluoroethylene-perfluoroalkoxyethylene copolymer), The valve body and the diaphragm are made of PTFE (polytetrafluoroethylene) or modified PTFE.

[0010] The method for manufacturing the diaphragm valve of the present invention includes the steps of: A method for manufacturing a diaphragm valve comprising: a valve body that contacts a valve seat of a valve box to close a flow path; and a diaphragm that supports the valve body so as to be displaceable in an axial direction, the valve body including a seal portion that contacts the valve seat; and a valve body that is connected to the diaphragm and supports the seal portion, A PTFE block made of PTFE or modified PTFE is placed in a concave mold, A PFA material made of pellet-shaped or sheet-shaped PFA is placed on the upper surface of the PTFE mass, While heating the inside of the mold, the PFA material is pressed from above with an upper mold, thereby melting the PFA material and integrating it with the PTFE mass, thereby producing a block in which a PFA layer is formed on the upper surface of the PTFE mass; The block is cut, and the PFA layer is formed into the seal portion, and the PTFE mass is formed into the valve body and the diaphragm.

[0011] It is desirable to cut the block so that the mold contact surface of the PFA layer is not cut but is left as a leading edge surface that abuts against the valve seat.

[0012] The heating inside the mold can be carried out so that the PFA material and the PTFE mass are heated to 320°C to 340°C.

[0013] The PFA layer is desirably formed to a thickness of 2 mm or more. Effect of the Invention

[0014] PTFE, modified PTFE, and PFA are all materials that are highly stable, non-reactive, and resistant to chemicals with respect to the liquids used in semiconductor manufacturing equipment, etc. Therefore, all of these materials are suitable for use as diaphragm valves.

[0015] The diaphragm valve of the present invention employs PTFE or modified PTFE for the diaphragm and the valve body of the valve disc. PTFE or modified PTFE has excellent flex life, so by making the diaphragm, which swings, expands and contracts repeatedly in reciprocating motion, from these materials, it is possible to provide reliability for repeated reciprocating motion.

[0016] On the other hand, PFA, which has excellent mechanical strength, is used for the seal part of the valve disc. PFA has inferior flex life to PTFE and modified PTFE, but has high mechanical strength. Therefore, by using PFA for the seal part, particle generation can be suppressed even if the seal part repeatedly hits the valve seat, and contamination of the liquid can be prevented.

[0017] Therefore, the diaphragm valve of the present invention has a diaphragm with excellent flexible life and a valve body with a seal portion with sufficient mechanical strength, so that the diaphragm valve has excellent durability and is suitable as a diaphragm valve which does not generate particles.

[0018] According to the manufacturing method of the diaphragm valve of the present invention, a pellet-like or sheet-like PFA is layered on a PTFE block, and then heated and pressurized to obtain an integrated block, which is then cut to produce the above-mentioned diaphragm valve. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 is a cross-sectional view of a diaphragm valve according to one embodiment of the present invention. [Diagram 2] FIG. 2 is a cross-sectional view of a diaphragm valve installed in a valve body, showing the valve in a closed state. [Diagram 3] FIG. 3 is a cross-sectional view of a diaphragm valve installed in a valve body, showing the valve in an open position. [Figure 4] FIG. 4 is an explanatory diagram showing a manufacturing method of a block that is the material for the diaphragm valve of the present invention. [Diagram 5] FIG. 5 is an image of how a diaphragm valve is obtained by cutting a block. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] A diaphragm valve 10 according to one embodiment of the present invention and a method for manufacturing the same will be described below with reference to the drawings.

[0021] 1 is a cross-sectional view taken along the axial direction of a diaphragm valve 10 of the present invention. The diaphragm valve 10 can be constructed by connecting a diaphragm 15 to the periphery of a valve body 11.

[0022] The diaphragm valve 10 is installed in a valve box 30 as shown in Figures 2 and 3. More specifically, the valve box 30 is configured such that an inflow flow path 31 and an outflow flow path 32 for liquid are partitioned by a valve seat 33, and the diaphragm valve 10 is disposed so that the valve element 11 can abut against the valve seat 33. Figure 2 shows a state in which the valve element 11 abuts against the valve seat 33 and the valve is closed (valve closed), and Figure 3 shows a state in which the valve element 11 is separated from the valve seat 33 and the valve is open (valve open).

[0023] 2 and 3, the valve element 11 has a seal portion 12 at its tip that abuts against a valve seat 33, and a valve body 13 that supports the seal portion 12 at its base end and is connected to a diaphragm 15. The valve body 13 has a connection portion 14 formed at its base end that is connected to a drive mechanism (not shown). In the drawings, the connection portion 14 has a thread groove engraved on its outer periphery and is screwed into the drive mechanism.

[0024] The drive mechanism is a mechanism for reciprocating the valve body 13 so as to be displaceable in the axial direction, and may be composed of, for example, an actuator, a ball screw, etc. The drive mechanism is partitioned from the liquid flowing inside the valve box 30 by the diaphragm valve 10, so that it is possible to keep out of contact with the liquid.

[0025] The diaphragm 15 is a disk-shaped thin plate, and the valve body 11 is connected to the center. An annular mounting portion 16 is formed on the outer periphery of the diaphragm 15. The diaphragm valve 10 is mounted to the valve box 30 by airtightly mounting the mounting portion 16 to the valve box 30.

[0026] The diaphragm 15 and the valve body 13 to which the diaphragm 15 is connected, and preferably the mounting portion 16 on the outer periphery of the diaphragm 15, are made of PTFE (polytetrafluoroethylene) or modified PTFE. PTFE or modified PTFE has excellent flex life properties, so by making the diaphragm 15, which is repeatedly reciprocated by the drive mechanism and swings, expands and contracts, and is subjected to bending, and the valve body 13 and mounting portion 16 connected thereto, from these materials, it is possible to provide reliability for repeated reciprocation. Therefore, the durability of the diaphragm valve 10 can be increased, and a long life can be achieved.

[0027] On the other hand, the seal portion 12 that abuts against the valve seat 33 is made of PFA (tetrafluoroethylene-perfluoroalkoxyethylene copolymer), which is a material different from PTFE or modified PTFE. PFA has a lower flex life than PTFE or modified PTFE, but its mechanical strength is higher than these materials. Therefore, by using PFA for the seal portion 12, even if the seal portion 12 repeatedly collides with the valve seat 33, the generation of particles and the like can be suppressed, and contamination of the liquid can be prevented. In addition, because of its high mechanical strength, the durability of the diaphragm valve 10 can be increased, and a longer life can be achieved.

[0028] Therefore, the diaphragm valve 10 of the present invention has excellent flexible life in the diaphragm 15 and its connecting parts, and the valve body 11 has a sealing portion 12 that has sufficient mechanical strength, making it suitable as a diaphragm valve 10 that has high durability, suppresses particle generation, and does not contaminate the liquid.

[0029] The diaphragm valve 10 having the above-mentioned structure can be produced by cutting a block 20 in which a PTFE layer 23 made of PFA is integrated with a PTFE block 21 made of PTFE or modified PTFE.

[0030] For example, a PTFE lump 21 and a pellet-shaped or sheet-shaped PFA material 22 are prepared. The PTFE lump 21 can be cylindrical or rectangular. The maximum thickness of the PTFE lump 21 is preferably 100 mm. An example of PTFE is M392 manufactured by Daikin Industries, Ltd. An example of modified PTFE is M112, M111, and M139 manufactured by Daikin Industries, Ltd., and TFM1600, TFM1700, and TFM1705 manufactured by 3M Japan, Ltd. An example of PFA is AP-230SH and AP-231SH manufactured by Daikin Industries, Ltd., and 451HP-J and 450HP-J manufactured by Mitsui-Chemours Fluoroproducts, Inc. The melt flow rate (MFR) of PFA is preferably 5 g / 10 min or less.

[0031] The PTFE lump 21 and the PFA material 22 are poured into a concave mold 40, as shown in Fig. 4(a). The mold 40 can be formed from a lower mold 41, a cylindrical mold 42, and an upper mold 43. After the PTFE lump 21 is placed in the mold 40, the PFA material 22 is placed on its upper surface. It is desirable to use an amount of PFA material 22 that will form a thickness of 2 mm or more, and desirably 2.1 mm or more, on the PTFE lump 21 by heating and pressurizing as described below. After the PFA material 22 is placed, the cylindrical mold 42 is closed with the upper mold 43 from above the PFA material 22.

[0032] Then, as shown in FIG. 4(b), the mold 40 is set in a press 44. A heat press can be used as the press 44, and in the figure, the mold 40 is disposed between press hot plates 45 and 46 facing each other vertically, and a spacer 47 is inserted between the upper mold 43 and the press hot plate 45. The press hot plates 45 and 46 heat and press the inside of the mold 40, and as shown in FIG. 4(c), the PFA material 22 is melted and completely integrated with the PTFE mass 21. The pressure (surface pressure) during the manufacture of the molds 41 and 43 is preferably about 10 to 40 kgf / cm2 (about 0.98 to 3.9 MPa), and the inside of the mold 40 is heated to a temperature (about 320°C to about 340°C) at which the PTFE mass 21 and the PFA material 22 melt, and after the PTFE mass 21 and the PFA material 22 melt, the mold 40 is cooled while applying pressure. If the surface pressure exceeds this value, the PFA material 22 may flow out from between the dies 42 and 43, making molding impossible.

[0033] 4(d) shows the block 20 removed from the mold 40. The block 20 is a hybrid material in which a PFA layer 23 formed by melting a PFA material is integrated onto a PTFE lump 21. According to the method of the present invention, the upper surface of the PFA layer 23 of the block 20 comes into contact with the upper mold 43 and is melted and solidified, so that the block 20 can have a flat mold transfer surface like an injection molded product.

[0034] The obtained block 20 is subjected to cutting as shown in Fig. 5 to cut out the diaphragm valve 10. In the figure, the PFA layer 23 is shown positioned on the lower side, and cutting is performed so that the PFA layer 23 portion becomes the seal portion 12 of the valve body 11 of the diaphragm valve 10, and the PTFE block 21 portion becomes the valve body 13, the connection portion 14, the diaphragm 15, and the mounting portion 16.

[0035] It is desirable to leave the surface of the PFA layer 23 that was in contact with the upper mold 43 of the seal portion 12 so that it becomes a tip surface that abuts against the valve seat 33 without cutting it. This makes it possible to prevent the generation of fine burrs or burrs due to cutting on the tip surface of the seal portion 12 and maintain flatness. Therefore, the seal portion 12 can achieve low dust generation due to contact with the valve seat 33 and also has high sealing properties.

[0036] By the above cutting process, as shown in FIG. 1, a diaphragm valve 10 can be obtained in which the sealing portion 12 is made of PFA and the other portions, i.e., the valve body 13, the connection portion 14, the diaphragm 15 and the mounting portion 16 are made of PTFE or modified PTFE.

[0037] For example, the outer diameter of the mounting portion 16 of the diaphragm valve 10 can be 10 mm to 100 mm, and is 20 mm in the illustration. The height of the valve body 11 including the seal portion 12, the valve body 13, and the connection portion 14 can be 5 mm to 100 mm, and is 8.5 mm in the illustration. The thickness of the PFA of the seal portion 12 can be 2 mm to 20 mm, and is 2 mm in the illustration.

[0038] 2 and 3, the mounting portion 16 of the obtained diaphragm valve 10 is attached to an annular mounting groove 34 provided in the valve body 30 with the sealing portion 12 facing the valve seat 33. A drive mechanism (not shown) is connected to the connection portion 14.

[0039] Thus, with inflow passage 31 filled with liquid, the drive mechanism is operated to open and close the valve. Figure 2 shows the valve closed, with seal portion 12 blocking valve seat 33 and preventing the flow of liquid. From this state, the drive mechanism is operated to move valve element 11 in the axial direction, upward in the figure, causing diaphragm 15 to swing upward, and seal portion 12 to move away from valve seat 33, opening the valve. As a result, liquid flows from inflow passage 31 to outflow passage 32, as shown by the arrow in the figure.

[0040] By repeatedly opening and closing the valve, the flow rate of the fluid can be controlled as desired.

[0041] The above description is for the purpose of explaining the present invention, and should not be interpreted as limiting the invention described in the claims or restricting the scope of the invention. Furthermore, the configuration of each part of the present invention is not limited to the above embodiment, and various modifications are possible within the technical scope described in the claims.

[0042] For example, the configuration of the diaphragm valve 10 is not limited to that shown in the figure, and for example, the diaphragm 15 may have a curved cross section. In addition, in the figure, the connection part 14 is formed integrally with the valve body 11, but if the drive mechanism has a head that biases the valve body 11 in the axial direction, the connection part 14 is not necessary.

[0043] In the above embodiment, the seal portion 12 is formed in a disk shape at the tip of the valve body 11, but it is sufficient that at least the portion of the seal portion 12 that abuts against the valve seat 33 is made of PFA. [Explanation of symbols]

[0044] 10 Diaphragm valve 11 Valve body 12 Seal part 13 Valve body 15 Diaphragm 30 Valve box 33 Valve seat

Claims

1. A method for manufacturing a diaphragm valve comprising: a valve body that contacts a valve seat of a valve box to close a flow path; and a diaphragm that supports the valve body so as to be displaceable in an axial direction, the valve body including a seal portion that contacts the valve seat; and a valve body that is connected to the diaphragm and supports the seal portion, A PTFE block made of PTFE or modified PTFE is placed in a concave mold; A PFA material made of pellet-shaped or sheet-shaped PFA is placed on the upper surface of the PTFE mass, While heating the inside of the mold, the PFA material is pressed from above with an upper mold, thereby melting the PFA material and integrating it with the PTFE mass, thereby producing a block in which a PFA layer is formed on the upper surface of the PTFE mass; The block is cut, and the PFA layer is formed on the seal portion, and the PTFE mass is formed on the valve body and the diaphragm. A method for manufacturing a diaphragm valve.

2. The cutting of the block is performed such that the mold contact surface of the PFA layer is not cut but is left as a leading end surface that abuts against the valve seat. A method for manufacturing the diaphragm valve according to claim 1.

3. Heating in the mold is carried out so that the PFA material and the PTFE mass are at 320°C to 340°C. A method for manufacturing the diaphragm valve according to claim 1 or 2.

4. The PFA layer is formed to a thickness of 2 mm or more. A method for manufacturing the diaphragm valve according to any one of claims 1 to 3.

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