JP2023083160A - diaphragm valve - Google Patents

Abstract

To suppress the generation of particles by making it hard to generate a clearance on a joint surface between a separating membrane part and a valve body in a diaphragm in which the separating membrane part and the valve body part are joined.SOLUTION: A diaphragm valve is equipped with a valve body 13 formed with a valve chamber 19, a diaphragm 15 that includes a separating membrane part 15b having a base part 15a at a center and a valve body part 15c joined to the base part 15a, and a drive part 17 that has a stem 35. The stem 35 includes a base end part 35a connected to the drive part 17, a coupling part 35b provided at a tip end part, and an intermediate part 35c that extends between the base end part 35a and the coupling part 35b and is thinner than the base end part 35a. The coupling part 35b is united in the valve body part 15c. Between the base end part 35b and the base part 15a of the diaphragm, an energizing member 51 energizing the base part 15a toward the coupling part 35b is disposed.SELECTED DRAWING: Figure 2

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diaphragm valve including a diaphragm in which a valve body portion and a diaphragm portion are joined to and away from a valve seat.

For example, when controlling the flow rate of a chemical solution used in a semiconductor manufacturing apparatus, a valve body portion supported at the center of a diaphragm portion that separates a flow path or valve chamber through which the chemical solution flows from a driving portion and a diaphragm portion is provided. Diaphragm valves are often used, which have diaphragms that are fitted. In the diaphragm valve, the flow rate is controlled by repeatedly elastically deforming the diaphragm portion to bring the valve body portion into and out of contact with the valve seat. Such a diaphragm portion is required to have chemical resistance because it is in contact with a chemical solution, and is required to have bending durability because it repeatedly undergoes elastic deformation. For this reason, the diaphragm is generally made of polytetrafluoroethylene (PTFE), which has high bending durability. Since injection molding cannot be applied to PTFE, the diaphragm is produced by cutting a sintered block after compression molding powdery PTFE. However, when the diaphragm is made of PTFE, particles are likely to be generated from the valve body portion of the diaphragm that repeatedly contacts and separates from the valve seat, since PTFE tends to generate dust. In semiconductor manufacturing, when particles are mixed into a chemical solution, the yield of semiconductor manufacturing is greatly affected. Therefore, it is preferable to suppress the generation of dust from the valve body portion of the diaphragm that is in contact with the chemical solution.

As one method for suppressing the generation of dust from the valve body, it is conceivable to form the valve body from perfluoroalkoxyalkane (PFA), which is a fluororesin material that hardly generates dust. On the other hand, since PFA has low bending durability, it is not suitable for diaphragms that undergo repeated elastic deformation. Therefore, it has been proposed to join a valve body portion made of PFA to a diaphragm portion made of PTFE.

For example, in Patent Document 1, a diaphragm membrane and a rod-shaped portion provided in the center of the diaphragm membrane are formed from PTFE, which is a first fluorine-based resin material, and an outer peripheral uneven surface is provided on the outer periphery of a part of the rod-shaped portion. The diaphragm member (that is, the diaphragm portion) is formed from PTFE, which is the first fluorine-based resin material, and the valve seat bearing is formed from PFA, which is the second injection-moldable fluorine-based resin material. A valve seat contact member (that is, a valve body portion) having a contact surface and a recess provided on the opposite side is formed, and the outer peripheral uneven surface formed on the outer periphery of the rod-shaped portion of the diaphragm member and the valve seat contact member Discloses a fluid control valve in which a diaphragm member and a valve seat abutting member are joined by fitting a rod-shaped portion into the recess so that the inner peripheral uneven surface formed on the inner periphery of the recess is closely engaged with each other. ing. Furthermore, in Patent Document 1, after an insert molding step of injection molding a second round bar from a second fluororesin material with a first round bar formed from a first fluororesin material inserted, discloses a method of manufacturing a fluid control valve in which a first round bar is cut into the shape of the above-described diaphragm member, and a second round bar is cut into the shape of the above-described valve seat contact member.

Japanese Patent No. 6873991

As in the technique disclosed in Patent Document 1, when a diaphragm member and a valve seat abutting member formed of different fluororesin materials are joined by engagement (mechanical connection) between the uneven surfaces, for example, the valve is closed. When an impact is applied to the resin bonded body, such as when the valve body and the valve seat come into contact with each other, minute gaps may occur between the uneven surfaces when the valve body is deformed due to the difference in material hardness. Also, the joined body expands and contracts due to temperature changes of the fluid, and minute gaps may be generated between the uneven surfaces due to the difference in expansion and contraction rates. In particular, in a fluid device such as a valve, when liquid enters and accumulates in such a gap, deterioration of the valve body portion is caused, causing a problem that particles increase over time. Furthermore, even when a joined body is formed by insert molding as in the technique disclosed in Patent Document 1, if an impact is applied to the resin joined body, such as when the valve body and the valve seat abut when the valve is closed, Due to the difference in material hardness, minute gaps may occur between the concave and convex surfaces when the valve body is deformed.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the problems existing in the prior art by making it difficult for a gap to form between the diaphragm and the valve body in a diaphragm in which the diaphragm and the valve body are bonded together, thereby preventing particles from forming. It is to suppress the occurrence.

In view of the above object, the present invention provides a valve body in which a first flow path, a second flow path, and a valve chamber communicating with the first flow path and the second flow path are formed; A diaphragm including a diaphragm portion having a base portion and a valve body portion joined to the base portion and supported by the diaphragm portion; are connected to each other to drive the valve body portion by the driving portion, and the valve body portion is opened and closed by contacting and separating from an annular valve seat formed around an opening from the first flow path to the valve chamber. A operative diaphragm valve, wherein the stem has a proximal end connected to the drive, a coupling, and a stem extending between and narrower than the proximal end and the coupling. and an intermediate portion, wherein the connection portion is coupled to the valve body portion, and a biasing member that biases the base portion toward the connection portion is connected to the base end portion and the base portion of the diaphragm. to provide a diaphragm valve disposed between

In the above diaphragm valve, the connecting portion of the stem extending from the drive portion is coupled to the valve body portion, and the biasing member disposed between the base end portion of the stem and the base portion of the diaphragm portion of the diaphragm moves the base portion. It is biased toward the connecting portion. As a result, the biasing member presses the base portion against the valve body portion coupled to the connecting portion at the distal end portion of the stem. Therefore, when the valve body portion abuts against the valve seat when the valve is closed, the valve body portion may be deformed due to the impact applied to the valve body portion, or the valve body portion and the base portion may be damaged due to the temperature change of the liquid in the valve chamber. Even if it expands and contracts, a gap is less likely to occur between the valve body portion and the base portion.

In the above diaphragm valve, the connecting hole extends through the base portion to the inside of the valve body portion, and an enlarged concave portion is provided on the inner peripheral surface of the end portion of the connecting hole located in the valve body portion. Preferably, the connecting portion of the stem is thicker than the intermediate portion, and the connecting portion of the stem press-fitted into the connecting hole is engaged with the enlarged recess to be connected to the valve body portion.

Further, it is preferable that the biasing member is a ring-shaped elastic member and is mounted around the intermediate portion, and it is more preferable that the elastic body is an O-ring.

The diaphragm portion may be made of polytetrafluoroethylene (PTFE), and the valve body portion may be made of perfluoroalkoxyalkane (PFA).

According to the present invention, when the valve body portion abuts against the valve seat when the valve is closed, the valve body portion may be deformed due to an impact applied to the valve body portion, or the valve body portion may be deformed due to the temperature change of the liquid in the valve chamber. Even if the base portion expands and contracts, a gap is less likely to occur between the valve body portion and the base portion. Therefore, it is possible to suppress the generation of particles from the valve body portion or the base portion due to the deterioration of the material due to the intrusion of the liquid in the valve chamber into the created gap.

1 is a cross-sectional view showing the overall configuration of one embodiment of a diaphragm valve according to the present invention; FIG. 2 is an enlarged view showing a diaphragm and a valve chamber in the diaphragm valve shown in FIG. 1; FIG.

Embodiments of a diaphragm valve according to the present invention will be described below with reference to the drawings.

First, referring to FIG. 1, the overall configuration of one embodiment of the diaphragm valve according to the present invention will be described. The diaphragm valve 11 includes a valve body 13 , a diaphragm 15 , and a driving portion 17 that drives the diaphragm 15 , and the driving portion 17 is attached to the upper portion of the valve body 13 .

A valve chamber 19 is formed in the center of the upper portion of the valve body 13 , and a first channel and a second channel communicating with the valve chamber 19 are also formed. In the valve chamber 19, an annular valve seat 21 is formed around the opening from the first flow path to the valve chamber 19, with which the diaphragm 15 contacts and separates. In the illustrated embodiment, the first flow path is an inlet flow path 25 extending from an inlet 23 formed in one of the opposing side surfaces of the valve body 13 and opening at the center of the bottom of the valve chamber 19 . In addition, as a second flow path, an outlet flow path 29 extending from an outflow port 27 formed in the other of the opposite side surfaces of the valve body 13 and opening to the side surface of the valve chamber 19 is formed. An annular valve seat 21 is formed around the opening from passage 25 to valve chamber 19 .

The drive unit 17 is connected to a drive unit housing 31 attached to the upper portion of the valve body 13 and having a mechanism housing space formed therein, a lid member 33 attached to the upper portion of the drive unit housing 31, and the diaphragm 15. and a drive mechanism that is housed in the mechanism housing space and drives the stem 35 . In this embodiment, a cylinder portion is formed as a mechanism accommodation space within the drive unit housing 31, and the drive mechanism is composed of a piston 37 accommodated in the cylinder portion and a coil spring 39 as an urging member. It is

The piston 37 has a piston body 37a slidably accommodated in the cylinder portion of the drive unit housing 31, and a guide shaft 37b extending upward from the piston body 37a. A stem 35 is connected to the piston body 37a so as to extend. The stem 35 is slidably inserted into a through hole provided through the bottom of the drive unit housing 31, and its tip is connected to the diaphragm 15 (more specifically, the valve body 15c, which will be described later). there is The outer peripheral surface of the piston body 37a is in contact with the inner peripheral surface of the cylinder portion so as to be slidable in the vertical direction. An upper space 41 surrounded by a surface (that is, the lower surface of the lid member 33), and a lower portion surrounded by the lower surface of the piston body 37a, the inner peripheral wall of the cylinder portion, and the bottom surface of the cylinder portion (that is, the bottom of the drive unit housing 31). It divides into space 43 and. The guide shaft 37b is slidably inserted into a through hole provided through the cover member 33, and guides the vertical movement of the piston 37. As shown in FIG.

The lid member 33 is formed with a vent 45 communicating with the cylinder section that defines the upper space 41 , so that ventilation can be performed between the upper space 41 and the outside through the vent 45 . . A working fluid supply port 47 communicating with the bottom of the cylinder portion defining the lower space 43 is formed in the side portion of the drive unit housing 31 , and the working fluid flows into the lower space 43 from the working fluid supply port 47 . can be supplied. Furthermore, a coil spring 39 is arranged in a compressed state between the lower surface of the lid member 33 (the ceiling surface of the cylinder portion) and the upper surface of the piston body 37a.

The stem 35 has a base end portion 35a connected to the piston body 37a, a connecting portion 35b provided at the distal end portion, and extending between the base end portion 35a and the connecting portion 35b and extending from the base end portion 35a and the connecting portion 35b. also includes a narrow intermediate portion 35c. The connecting portion 35b preferably has a conical shape that tapers toward the tip. This conical shape makes it easy to press-fit the connecting portion 35b of the stem 35 into a connecting hole 49, which will be described later.

The diaphragm 15 includes a diaphragm portion 15b having a base portion 15a projecting downward at its central portion, and a valve body portion 15c joined to the base portion 15a. The diaphragm portion 15b is formed so as to extend radially outward from the outer peripheral portion of the upper end portion of the base portion 15a, and the outer periphery of the diaphragm portion 15b has a substantially circular shape. Further, the outer peripheral edge of the diaphragm portion 15b is sandwiched between the upper surface of the peripheral region of the upper opening of the valve chamber 19 of the valve body 13 and the bottom surface of the drive unit housing 31. As shown in FIG. In this manner, the diaphragm 15 partitions the valve chamber 19 and the driving portion 17 while supporting the valve body portion 15c above the valve chamber 19 via the diaphragm portion 15b. In the illustrated embodiment, the valve body portion 15 c has a shape in which a truncated cone is connected to a cylinder, and is arranged so that the bottom surface (valve seat contact surface) faces the valve seat 21 . It is The base portion 15a is joined to the valve body portion 15c so that its peripheral surface is smoothly connected to the side surface of the truncated cone portion of the valve body portion 15c. However, if the valve body portion 15c is supported in the valve chamber 19 by the diaphragm portion 15b and can contact and separate from the valve seat 21 to open and close the opening from the inlet flow path 25 to the valve chamber 19, the shape of the valve body portion 15c is limited. not something.

In the diaphragm 15, the diaphragm portion 15b in particular is a portion that undergoes repeated bending. 21, it is made of PFA with low dust emission, and the base portion 15a, the diaphragm portion 15b, and the valve body portion 15c are made of different members made of different materials. there is PTFE or PFA forming the diaphragm 15 may be chemically modified or crosslinked by ionizing radiation. In particular, PTFE is preferably chemically modified. The drive unit housing 31, lid member 33, stem 35, and piston 37 of the drive unit 17 can be made of appropriate materials such as polyvinylidene fluoride (PVDF), PTFE, PFA, and polychlorotrifluoroethylene (PCTFE). .

The base portion 15a and the valve body portion 15c may be joined together by mechanical coupling such as engagement of uneven surfaces, screwing, or insert molding, or by welding or bonding with an adhesive. However, when used in the manufacture of semiconductors, etc., mechanical bonding may cause particles to be released into the liquid in the valve chamber 19 and contaminate the liquid due to sliding at the joint. Ingredients of the agent may leach into the liquid in the valve chamber and contaminate the liquid. Therefore, it is preferable to join the base portion 15a and the valve body portion 15c by welding. Welding can be performed by, for example, laser welding, heat welding, hot air welding, induction welding, or firing.

The diaphragm 15 is provided with a connecting hole 49 extending through the base portion 15a and extending to the inside of the valve body portion 15c. It is adapted to be coupled within the body portion 15c. In the illustrated embodiment, an annular enlarged concave portion 49a is provided on the inner peripheral surface of the distal end portion of the connecting hole 49 located in the valve body portion 15c, and a locking hole portion is formed in the distal end portion. there is That is, the locking hole portion is thicker than the intermediate hole portion extending from the base portion 15a to the inside of the valve body portion 15c, and forms a stepped portion at the boundary portion. Also, the connecting portion 35b of the stem 35 is thicker than the intermediate portion 35c. The connecting portion 35b at the tip of the stem 35 is press-fitted into the connecting hole 49, and the connecting portion 35b is engaged with the enlarged concave portion 49a. Body portion 15c and stem 35 are connected. By connecting the valve body portion 15c of the diaphragm 15 and the stem 35 in this manner, the diaphragm 15 (more specifically, the valve body portion 15c) moves through the stem 35 as the piston 37 moves up and down. The seat 21 can be moved toward and away from it. Further, if the stem 35 is connected to the valve body portion 15c as described above, even if the base portion 15a and the valve body portion 15c are separated, the valve body portion 15c will drop from the base portion 15a. be able to prevent this from happening.

The connecting portion 35b at the tip of the stem 35 and the valve body portion 15c are connected by screwing with a male thread provided on the outer peripheral surface of the connecting portion 35b and a female thread provided on the inner peripheral surface of the connecting hole 49, or by an adhesive. Other methods such as gluing are also possible. However, when the connecting portion 35b at the tip of the stem 35 and the valve body portion 15c of the diaphragm 15 are screwed together, a gap should occur between the joint surface between the base portion 15a of the diaphragm 15 and the valve body portion 15c. Occasionally, particles generated in the connecting hole 49 during screwing may pass through the gap and be released into the liquid in the valve chamber 19 to contaminate the liquid. Therefore, it is preferable to connect the connecting portion 35b at the tip of the stem 35 and the valve body portion 15c by a method other than screwing.

In the diaphragm valve 11, a biasing member 51 is provided between the base end portion 35a of the stem 35 (more specifically, the stepped portion between the base end portion 35a and the intermediate portion 35c) and the base portion 15a of the diaphragm portion 15b of the diaphragm 15. is sandwiched therebetween, and a biasing member 51 biases the base portion 15a toward the connecting portion 35b at the tip of the stem 35. As shown in FIG. As a result, the base portion 15a is pressed against the valve body portion 15c coupled to the connecting portion 35b by the biasing member 51, and the impact of the valve body portion 15c coming into contact with the valve seat 21 when the valve is closed causes the valve body portion 15c to move. is deformed (when the base portion 15a and the valve body portion 15c are joined, even if the joint between the base portion 15a and the valve body portion 15c is destroyed by the deformation), the base portion 15a and the valve body portion 15c. Similarly, even if there is a difference in the amount of expansion and contraction due to the temperature change of the liquid in the valve chamber 19 due to the difference in expansion/contraction rate between the base portion 15a and the valve body portion 15c, the base portion 15a and the valve body portion 15c is less likely to create a gap. Therefore, the liquid in the valve chamber 19 that has entered the gap between the base portion 15a and the valve body portion 15c deteriorates the material forming the base portion 15a or the valve body portion 15c, thereby preventing the particles from increasing with time. can be suppressed.

In the illustrated embodiment, an O-ring attached to the outer periphery of the intermediate portion 35c of the stem 35 is used as the biasing member 51. As shown in FIG. However, the biasing member 51 is not limited to an O-ring as long as it can apply a biasing force to the base portion 15a. For example, a coil spring or spring washer made of resin or metal, an annular rubber packing member, or the like arranged to surround the intermediate portion 35c of the stem 35 may be used as the biasing member 51 . Metal coil springs, spring washers, rubber O-rings, and annular packing members may be covered with PFA or PTFE. Peroxide vulcanization is preferred as the rubber vulcanization method. Fluororubber is preferable as the rubber material for the O-ring and the annular packing member. If an O-ring is used as the biasing member 51, lubricating oil or the like used in the driving portion 17 leaks into the valve chamber 19 even if a gap is generated between the base portion 15a and the valve body portion 15c. It is possible to achieve the effect of preventing this.

Next, operation of the diaphragm valve 11 will be described with reference to FIGS. 1 and 2. FIG. As shown in FIG. 1, when the working fluid is not supplied to the driving part 17 from the working fluid supply port 47, the piston 37 of the driving part 17 is pushed downward by the coil spring 39. . As a result, the valve body portion 15c moves toward the valve seat 21 through the stem 35 and is pressed against the valve seat 21, so that the diaphragm valve 11 is closed as shown in FIG. Along with this, the diaphragm portion 15 b supporting the valve body portion 15 c via the base portion 15 a is also deformed in a direction away from the driving portion 17 .

When the working fluid is supplied to the working fluid supply port 47 of the driving portion 17 from the valve closed state, the fluid pressure of the working fluid flowing into the lower space 43 of the cylinder portion acts upward on the piston main body 37a, and the piston 37 acts as a coil spring. It is pushed up against the biasing force of 39. At this time, the air in the upper space 41 is released to the outside through the vent 45 . As a result, the valve body portion 15c is moved away from the valve seat 21 via the stem 35, and the diaphragm valve 11 is opened. Along with this, the diaphragm portion 15b is also deformed in a direction approaching the driving portion 17. As shown in FIG. When the supply of the working fluid to the working fluid supply port 47 is stopped, the piston 37 is again urged downward by the coil spring 39 to press the valve body portion 15c against the valve seat 21, closing the valve again. state.

In the diaphragm valve 11, the valve body portion 15c repeatedly contacts and separates from the valve seat 21, and particularly when the valve body portion 15c contacts the valve seat 21, particles are likely to be generated due to the impact. For this reason, in the diaphragm valve 11, the diaphragm portion 15b (including the base portion 15a) of the diaphragm 15, which repeatedly deforms (bends), is made of PTFE, which has high bending durability. The valve body portion 15c, which tends to generate particles repeatedly, is desirably made of PFA with low dust generation. In such a case, it is necessary to form the base portion 15a and the valve body portion 15c of the diaphragm 15 separately, and join the valve body portion 15c made of PFA to the base portion 15a made of PTFE. . Joining is performed by mechanical bonding, welding, bonding with an adhesive, or the like.

However, in the diaphragm in which the base portion 15a and the valve body portion 15c are joined together, when the valve body portion 15c is pressed against the valve seat 21, the valve body portion may be deformed by welding or adhesion even in the case of mechanical connection. Even if the joint between the base portion 15a and the valve body portion 15c is destroyed due to the deformation of the valve body portion 15c, the valve body portion 15c will be deformed by the impact during pressure contact, and the deformation of the valve body portion 15c will cause the base portion 15a and the valve body to break. A gap may occur between the body portion 15c and the body portion 15c. In addition, due to the difference in expansion/contraction rate between the base portion 15a and the valve body portion 15c, a gap is created between the base portion 15a and the valve body portion 15c as the liquid in the valve chamber 19 expands and contracts due to temperature changes. It may occur. However, in the diaphragm 15, the valve body portion 15c is coupled to the connecting portion 35b of the stem 35, and the base end portion 35a of the stem 35 (more specifically, the stepped portion between the base end portion 35a and the intermediate portion 35c) and the diaphragm A biasing member 51 for biasing the base portion 15a toward the connecting portion 35b of the stem 35 is arranged between the base portion 15a of the diaphragm portion 15b of 15 and the base portion 15a. Therefore, even if the valve body portion 15c is deformed, or if the base portion 15a and the valve body portion 15c are joined by welding or the like, the valve body portion 15c is deformed and the joint is destroyed. Even if the liquid in the chamber 19 expands and contracts due to temperature changes, the base portion 15a is pressed against the valve body portion 15c coupled to the connecting portion 35b of the stem 35, and the base portion 15a and the valve body portion 15c are separated. It is difficult to create a gap between As a result, the liquid in the valve chamber 19 enters the gap formed between the base portion 15a and the valve body portion 15c, and particles are released from the base portion 15a and the valve body portion 15c deteriorated by the intruding liquid into the valve chamber. Contamination of the liquid by being released into the liquid in 19 can be suppressed. Therefore, it becomes easier to adopt the option of forming the base portion 15a and the valve body portion 15c of the diaphragm 15 separately from different materials and then joining them to each other.

Although the diaphragm valve 11 according to the invention has been described above with reference to the illustrated embodiments, the invention is not limited to the illustrated embodiments. For example, in the illustrated embodiment, the connecting portion 35b of the stem 35 engages an enlarged recess 49a provided at the distal end of a connecting hole 49 located within the valve body portion 15c of the diaphragm 15, thereby The connecting portion 35b is coupled to the valve body portion 15c, and the diaphragm 15 and the stem 35 are connected. However, as long as the valve body portion 15c of the diaphragm 15 and the connecting portion 35b of the stem 35 can be connected, the connecting method is not limited. For example, the connecting portion 35b may be coupled to the end portion of the connecting hole 49 located within the valve body portion 15c by adhesion or screwing. In this case, the connecting portion 35b of the stem 35 need not be thicker than the intermediate portion 35c. In addition, the present invention can be applied to a constant pressure valve, a flow control valve, or the like, which includes a diaphragm portion including a valve body portion and a base portion, in addition to the illustrated diaphragm valve 11. It is possible to achieve the same effects as those of the embodiment described above.

REFERENCE SIGNS LIST 11 diaphragm valve 13 valve body 15 diaphragm 15a base portion 15b diaphragm portion 15c valve body portion 19 valve chamber 21 valve seat 25 inlet channel 29 outlet channel 35 stem 35a base end portion 35b connecting portion 35c intermediate portion 49 connecting hole 49a enlarged Recess 51 biasing member

Claims (5)

a valve body in which a first flow path, a second flow path, and a valve chamber communicating with the first flow path and the second flow path are formed; and a diaphragm portion having a base portion in the center. a diaphragm including a valve body portion joined to the base portion and supported by the diaphragm portion; and a driving portion having a stem. A diaphragm valve for opening and closing by driving a valve body portion and bringing the valve body portion into contact with and separating from an annular valve seat formed around an opening from the first flow path to the valve chamber,
the stem includes a base end connected to the driving part, a connecting part, and an intermediate part extending between the base end and the connecting part and thinner than the base end, the connecting part is coupled to the valve body portion, and a biasing member that biases the base portion toward the connecting portion is disposed between the base end portion and the base portion of the diaphragm. A diaphragm valve characterized by A connecting hole extends through the base portion to the inside of the valve body portion, and an enlarged concave portion is provided on an inner peripheral surface of a distal end portion of the connecting hole located in the valve body portion, and the stem is provided with an enlarged recess. 2. The diaphragm valve according to claim 1, wherein the connecting portion is thicker than the intermediate portion, and the connecting portion of the stem press-fitted into the connecting hole engages with the enlarged concave portion and is connected to the valve body portion. . 3. The diaphragm valve according to claim 1, wherein said biasing member comprises a ring-shaped elastic member mounted around said intermediate portion. 4. The diaphragm valve of claim 3, wherein said resilient member is an O-ring. 5. A diaphragm valve according to claim 1, wherein said diaphragm portion is made of polytetrafluoroethylene (PTFE), and said valve body portion is made of perfluoroalkoxyalkane (PFA).

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