JP2011122718A - Valve seat processing method, valve body, and fluid control valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a valve seat processing method which can secure the flatness of a valve seat so as not to produce particles. <P>SOLUTION: In the valve seat processing method for securing a flatness of a plastic valve seat of a valve body 1, a flat abutting surface 14b of a heated heating member 14 is pressed against a sealing surface of the valve seat. After melting the sealing surface, the flat abutting surface 14b of the heating member 14 is pulled away from the sealing surface of the valve seat. The desirable material of the heating member 14 is the same material as a die used when the valve body 1 is injection molded. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a valve seat processing method for obtaining flatness of a valve seat provided in a resin valve body, a valve body having a valve seat processed by the valve seat processing method, and a fluid control valve.

  For example, in a valve used in a semiconductor manufacturing line, the valve body is brought into contact with or separated from a valve seat provided in the valve body by the driving force of the driving unit, and the supply and blocking of the chemical solution is controlled. Some chemical solutions contain hydrochloric acid or the like, and the valve body has a liquid contact surface made of resin in order to ensure corrosion resistance. In general, the valve body is divided into parts such as PFA (tetrafluoroethylene perfluoroalkyl vinyl ether copolymer), PVDF (polyvinylidene fluoride) and PP (polypropylene) for mass production at low cost. The mold is formed by injecting into a closed mold gate, filling the cavity, cooling the mold, and then dividing the mold at the dividing surface and taking out the molded product.

  In order to simplify the structure of the mold forming the valve body, a split surface is provided on the valve seat, and a molding defect may occur on the seal surface of the valve seat of the valve body taken out from the mold. It was. For example, if a weld line or a burr occurs on the sealing surface of the valve seat as a molding defect and the flatness of the sealing surface of the valve seat is low, the sealing performance is deteriorated. For this reason, conventionally, the sealing surface of the valve seat of the injection molded valve body is machined (for example, cutting or polishing with a lathe) to improve the flatness of the valve seat on the micron order.

JP 2009-002442 A

  However, when the flatness of the valve seat is improved by machining as described above, mussels are generated on the machined surface. FIGS. 16 and 18 show electron micrographs (magnification: × 1000) obtained by partially photographing the outer edge portion of the machined valve seat, and FIGS. 17 and 19 are diagrams corresponding to the electron micrographs. . For example, as shown at P31 in FIG. 17 and FIG. 19, musiness is generated so that the sealing surface of the valve seat becomes fluffy, or as shown at P32 in FIG. 17 and FIG. 19, the edge portion of the valve seat is scratched by machining. The peeled part protrudes to the side of the valve seat. These mussels are not so large as to cause fluid leakage when the valve is closed, but they may be peeled off from the valve seat by the flow of fluid passing through the valve seat and become particles. Particles are a problem because they cause problems such as lowering the yield of wafers that form films in the reaction chamber. In particular, in recent years, microfabrication has progressed in the semiconductor manufacturing process, and high cleanliness has been demanded. As part of this, reduction of particles has been strongly demanded.

  The present invention has been made to solve the above-described problems, and provides a valve seat processing method, a valve body, and a fluid control valve that can increase the flatness of a valve seat so that particles are not generated. Objective.

In order to solve the above-described problem, a valve seat processing method according to one aspect of the present invention is a valve seat processing method for obtaining flatness of a resin valve seat of a valve body. After the surface is pressed against the sealing surface of the valve seat, the heating member is separated from the sealing surface.
Here, the “flatness of the valve seat” refers to a flatness on the order of microns.

  In the above configuration, it is desirable that a recessed valve seat forming recess along the valve seat is formed on the contact surface.

  In the above configuration, it is desirable that the material of the heating member is the same material as a mold used when the valve body is injection-molded.

  In the above configuration, it is desirable to control the heating temperature of the heating member within a melting temperature range in which the material forming the valve seat melts.

  In the above configuration, it is desirable that the valve body is placed on the contact surface of the heating member via the valve seat.

Moreover, the valve body which concerns on 1 aspect of this invention has the valve seat processed by the said valve seat processing method.
A fluid control valve according to an aspect of the present invention includes a valve body having a valve seat processed by the valve seat processing method, and is connected to the valve body so that the valve body abuts or separates from the valve seat. And a drive unit.

  In the valve seat processing method of the above aspect, when the flat contact surface of the heated heating member is pressed against the seal surface of the valve seat, the seal surface melts and becomes flat following the contact surface of the heating member, and molding Eliminate the defects. When the heating member is separated from the sealing surface, the sealing surface is solidified and becomes a smooth flat surface. In such a valve seat machining method, no squeak is generated on the seal surface. Therefore, when the fluid control valve using the valve body having the valve seat machined by the valve seat machining method performs fluid control, the seal surface mus Is not peeled off from the sealing surface. Therefore, according to the valve seat processing method, the valve body, and the fluid control valve of the above aspect, the flatness of the valve seat can be obtained so that particles are not generated.

In the above configuration, since the recessed portion of the valve seat forming recess along the valve seat is formed on the contact surface, the sealing surface melts and becomes flat following the contact surface of the heating member, resulting in a molding defect. Can be eliminated. When the heating member is separated from the sealing surface, the sealing surface is solidified and becomes a smooth flat surface. For this reason, no mess is generated on the sealing surface. When a fluid control valve using a valve body having a valve seat machined by the valve seat machining method performs fluid control, there is no mess on the seal surface, so the mess are peeled off from the seal surface and become particles. There is nothing. Therefore, according to the valve seat processing method, the valve body, and the fluid control valve of the above aspect, the flatness of the valve seat can be obtained so that particles are not generated.
Further, when the heating member is flat, it is possible to eliminate a minute burr formed at the valve seat end portion of the valve seat. Particles can be further reduced by eliminating minute burrs at the valve seat end.
Further, the surface roughness of the valve seat forming recess on the hot plate side is transferred to the valve seat surface. Therefore, the smoothness of the valve seat surface can be greatly improved.
In addition, since the size of the valve seat portion can be managed by the size of the valve seat forming recess, a fluid control valve having a valve seat with good dimensional accuracy can be provided easily and inexpensively.

  In the above configuration, since the material of the heating member is the same as the mold used when the valve body is injection-molded, when the sealing surface of the valve seat is heated by the heating member, metal ions different from the mold are generated. Not injected into the valve seat. Therefore, according to the above configuration, when the valve body is used for fluid control, ions different from the mold are eluted from the valve seat and can be prevented from adversely affecting the semiconductor manufacturing process, for example.

  In the above configuration, the processing temperature of the heating member is controlled within the melting temperature range of the material forming the valve seat, so that the seal surface of the valve seat is fluidized by transferring heat from the contact surface of the heating member. It melts easily and eliminates molding defects and tends to become flat.

  In the above configuration, the valve body is placed on the contact surface of the heating member via the valve seat, and the seal surface of the valve seat is pressed against the contact surface of the heating member by the weight of the valve body. The load pressed against the contact surface of the heating member can be stabilized, and the flatness of the valve seat can be stably obtained.

It is sectional drawing of the valve body to which the valve seat processing method which concerns on embodiment of this invention is applied. It is an external view of a fluid control valve. It is a schematic block diagram of a valve seat processing apparatus. It is a schematic block diagram of a heating member. It is the electron micrograph (magnification: * 1000) which image | photographed the outer edge part of the valve seat before performing valve seat processing partially. In this electron micrograph, the valve seat is taken from the seal surface side. It is a figure equivalent to the electron micrograph shown in FIG. It is the electron micrograph (magnification: x1000) which carried out partial photography of the side edge part outside a valve seat after giving valve seat processing. In this electron micrograph, the valve seat is taken from the seal surface side. It is a figure equivalent to the electron micrograph shown in FIG. It is a schematic block diagram of an durability test apparatus. It is the figure which displayed the test result of the metal ion elution test as an index. It is a figure which shows valve seat processing conditions, Comprising: Time (sec) is shown on a vertical axis | shaft and temperature (degreeC) is shown on a horizontal axis | shaft. It is an image figure which shows the partial cross section of the valve seat state of an untreated goods. It is an image figure which shows the partial cross section of the valve seat state in which the molding defect remains after valve seat processing. It is an image figure which shows the partial cross section of the valve seat state which the edge part melt | dissolved after valve seat processing. It is an image figure which shows the partial cross section of the valve seat state which succeeded in valve seat processing. It is the electron micrograph (magnification: * 1000) which image | photographed the outer edge part of the valve seat which performed the machining partially. This electron micrograph is a photograph of the valve seat taken from the sealing surface side. It is a figure corresponded to the electron micrograph shown in FIG. It is the electron micrograph (magnification: * 1000) which image | photographed the outer edge part of the valve seat which performed the machining partially. This electron micrograph is a photograph of the valve seat taken from the sealing surface side. It is a figure equivalent to the electron micrograph shown in FIG. It is a schematic block diagram of the contact surface of the heating member in 2nd Embodiment. It is the electron micrograph (magnification: x1000) (1) which carried out partial photography of the outside edge part of the valve seat after performing valve seat processing in a 2nd embodiment. In this electron micrograph, the valve seat is taken from the seal surface side. It is a figure corresponded to the electron micrograph shown in FIG. It is the electron micrograph (magnification: x1000) (2) which carried out partial photography of the outside edge part of the valve seat after performing valve seat processing in a 2nd embodiment. In this electron micrograph, the valve seat is taken from the seal surface side. It is a figure corresponded to the electron micrograph shown in FIG. It is a schematic block diagram of the state which does not have a valve seat formation recessed part in the contact surface of a heating member. It is the elements on larger scale of the valve seat after giving a valve seat process with a heating member among FIG. It is the electron micrograph (magnification: x1000) which carried out partial photography of the outside edge part of a valve seat when not performing valve seat processing in a 2nd embodiment. In this electron micrograph, the valve seat is taken from the seal surface side. It is a figure equivalent to the electron micrograph shown in FIG.

(First embodiment)
Hereinafter, an embodiment of a valve seat processing method, a valve body, and a fluid control valve according to the present invention will be described with reference to the drawings. FIG. 1 shows a cross-sectional view of a valve body 1 to which a valve seat machining method according to an embodiment of the present invention is applied. FIG. 2 is an external view of the fluid control valve 8.
<Valve body configuration>
As shown in FIG. 2, for example, the valve body 1 shown in FIG. 1 includes a drive unit 10 connected to the upper surface to form a fluid control valve 8, and is assembled to a semiconductor manufacturing line via a mounting plate 9. The valve body 1 shown in FIG. 1 has a wetted part made of fluororesin and has corrosion resistance, and a resin diaphragm valve element (not shown) is brought into contact with or separated from the valve seat 6 by the driving force of the driving part 10. Thus, the communication state of the first and second ports 4 and 5 is controlled.

  The valve body 1 shown in FIG. 1 is made by injecting fluororesin such as PFA, PVDF, PP, etc. into a mold gate, filling the cavity, cooling the mold, then opening the mold and taking it out of the cavity. It is formed. A valve chamber forming hole 2 for forming a valve chamber with a diaphragm valve body (not shown) is formed in a cylindrical shape on the upper surface of the valve body 1. The valve body 1 has a mounting groove 3 in which an outer edge portion of a diaphragm valve body (not shown) is attached along the outer periphery of the opening portion of the valve chamber forming hole 2, and an outer edge of the diaphragm valve body (not shown) between the valve body 1 and the drive unit 10. The part is sandwiched. In the valve body 1, the valve hole 7 is provided coaxially with the valve chamber forming hole 2, and the first port 4 and the second port 5 communicate with each other via the valve hole 7 and the valve chamber forming hole 2. A valve seat 6 projects from the inner wall of the valve chamber forming hole 2 along the outer periphery of the opening where the valve hole 7 opens. The valve seat 6 is provided with a flat tip, and a sealing surface 6a is provided that seals by contacting a diaphragm valve body (not shown). The sealing surface 6a has a micron order flatness by a valve seat processing method to be described later. In the present embodiment, the flatness of the seal surface 6a is in the range of 5 μm or more and less than 1 mm.

<Configuration of valve seat processing device>
In FIG. 3, the schematic block diagram of the valve seat processing apparatus 11 is shown.
The valve seat processing device 11 processes the seal surface 6 a of the valve seat 6 of the valve body 1. A stage 13 is held by a guide 12 of the valve seat processing apparatus 11 so as to reciprocate linearly in the vertical direction in the figure. The stage 13 is given a driving force in the vertical direction in the figure by a cylinder (not shown). The heating member 14 is disposed on a through hole formed in the central portion of the stage 13, and the stage 13 moves up and down relatively with respect to the heating member 14.

In FIG. 4, the schematic block diagram of the heating member 14 is shown.
The heating member 14 is provided with the same material as the mold used when the valve body 1 is injection molded. In the present embodiment, the heating member 14 and the mold are made of a chromium nickel alloy. The heating member 14 can be inserted into the valve chamber forming hole 2 of the valve body 1 and has a block shape in which a contact surface 14 b that contacts the valve seat 6 is provided larger than the outer shape of the valve seat 6. The rod-shaped heater 15 is inserted into a heater insertion hole 14 a formed at the center of the heating member 14 and is fixed to the heating member 14 by a set screw 16 so as to heat the entire heating member 14. The heating member 14 has a thermocouple 17 attached near the contact surface 14b, and measures the temperature of the contact surface 14b.

  The control device 18 is a known microcomputer. The control device 18 is connected to the heater 15 and the thermocouple 17 and heats the heating member 14 with the heater 15 based on the temperature measured by the thermocouple 17 and controls the temperature of the heating member 14 to a set temperature. Here, it is desirable to set the set temperature of the heating member 14 within the melting temperature range of the fluororesin that is the material of the valve body 1. When the temperature of the heating member 14 exceeds the melting temperature range, the melted resin is mixed and deteriorated, and when the temperature of the heating member 14 is less than the melting temperature range, the valve seat 6 is hard and deformed. It is because it is not possible. Furthermore, the set temperature of the heating member 14 is set to “an intermediate value of the melting temperature range of the fluororesin that is the material of the valve body 1 ± 30% of the temperature difference between the upper limit value and the lower limit value of the melting temperature range”. It is desirable. For example, when the material of the valve body 1 is PFA, since the melting temperature range of PFA is 305 to 315 ° C., the set temperature of the heating member 14 is 310 ° C. ± 3 ° C. which is an intermediate value of the melting temperature range. Good. In the present embodiment, the set temperature of the heating member 14 is 310 ° C. with respect to the PFA valve body 1. The controller 18 preferably stores the set temperature of the heating member 14 for each type of fluororesin so that the operator can select the set temperature of the heating member 14 according to the material of the valve body 1. This is because even if the operator does not know the melting temperature range of the fluororesin, the set temperature of the heating member 14 is set so that the valve seat processing operation can be performed.

<Valve seat processing method>
In the valve seat 6 of the valve body 1 (untreated product) after injection molding, for example, a molding defect as shown in the electron micrograph of FIG. 5 corresponding to P11 and P12 of FIG. 6 occurs on the seal surface 6a. ing. For example, when the mold dividing surface for molding the valve body 1 is on the seal surface 6a of the valve seat 6, a weld line P11 is formed on the seal surface 6a or the mold is filled with fluororesin. When the mold is later divided and the molded product is taken out, a molding burr P12 is generated at the edge portion of the seal surface 6a. Since the molding defects P11 and P12 may cause a decrease in sealing performance and the like, the valve body 1 is processed so that the seal surface 6a of the valve seat 6 is flat using the valve seat processing apparatus 11.

  The valve seat processing apparatus 11 normally raises the stage 13 and arranges the surface of the stage 13 on which the valve body 1 is placed at a position higher than the contact surface 14b of the heating member 14 (of the stage 13). The position is hereinafter referred to as “initial position”). The valve body 1 is set on the stage 13 in the initial position with the valve seat 6 facing downward. At this time, the valve seat 6 is disposed above the heating member 14. When a valve seat processing start button (not shown) of the valve seat processing apparatus 11 is pressed, a cylinder (not shown) is driven to lower the stage 13 along the guide 12. After the valve seat 6 is brought into contact with the heating member 14, the stage 13 continues to descend further, and the valve body 1 is placed on the heating member 14 via the valve seat 6 and moved to the valve seat machining position where the valve body 1 is separated from the valve body 1. To do. As a result, the seal surface 6 a of the valve seat 6 is pressed against the contact surface 14 b of the heating member 14 by the weight of the valve body 1.

  The heating member 14 is heated to a set temperature (here, 310 ° C.) by the heater 15. Therefore, the seal surface 6a pressed against the contact surface 14b is heat-transferred from the contact surface 14b and the surface is melted. The molten resin has fluidity, flows into the depression of the weld line P11, fills the weld line P11, and makes the generated portion of the weld line P11 flush with the surface of the seal surface 6a. Further, the molding burr P12 generated on the seal surface 6a is softened by the heat of the heating member 14, and is crushed so as to be flush with the surface of the seal surface 6a. Since the surface of the sealing surface 6a is also softened by the heat of the heating member 14, the molten resin of the molding burr P12 and the resin that has flowed into the weld line P11 are fused with the molten resin of the surface of the sealing surface 6a. It is difficult to create a boundary surface between the resin part.

  When a predetermined time (in this case, 10 seconds) elapses after the valve seat 6 is pressed against the heating member 14, the stage 13 rises from the valve seat processing position and comes into contact with the valve body 1, and then further rises to reach the valve seat 6 The valve body 1 is lifted so as to separate it from the heating member 14. When the stage 13 returns to the initial position, the valve body 1 is removed from the stage 13. The operation of placing or removing the valve body 1 on the stage 13 may be performed by a robot or may be performed manually by an operator.

  The valve body 1 removed from the valve seat processing apparatus 11 is naturally cooled and solidified in a state where the seal surface 6a is flattened. For example, as shown in the electron micrograph of FIG. 7 corresponding to P21 in FIG. 8, the valve seat 6 is filled with resin in the weld line shown in the electron micrograph of FIG. 5 corresponding to P11 in FIG. As shown in the electron micrograph of FIG. 7 in the portion corresponding to P22 in FIG. 8, the portion corresponding to P12 in FIG. 6 is shown in the electron micrograph in FIG. The molded burr P12 is solidified in a state where it is crushed and flush with the seal surface 6a. Therefore, as shown in the electron micrograph of FIG. 7, the valve seat 6 processed by the heating member 14 has the sealing surface 6a that eliminates the molding defects P11 and P12 (see FIGS. 5 and 6), and the valve seat. The flatness is improved from before the processing, and the processed seal surface 6a is also made by melting and solidifying the resin, so that it is smooth and does not cause stuffiness.

  The valve body 1 processed in this way forms a fluid control valve 8 by sandwiching a diaphragm valve body (not shown) between the drive unit 10 and is used for fluid control. As shown in FIGS. 7 and 8, the valve body 1 has a smooth flat sealing surface 6a of the valve seat 6 and does not generate burrs on the sealing surface 6a as shown in FIGS. No particles are generated from the valve seat 6 even when the valve opening / closing operation is repeated by bringing a diaphragm valve body (not shown) into contact with or separating from the surface 6a.

<Durability test>
Next, an endurance test for examining the influence of the valve seat processing according to the present embodiment on the durability of the valve body will be described. FIG. 9 is a schematic configuration diagram of the durability test apparatus 21.
The endurance test apparatus 21 moves the fluid control valve 8 in which the air-operated driving unit 10 is attached to the valve body 1 subjected to the valve seat processing of the present embodiment, and moves the first and second ports 4 and 5 of the valve body 1 up and down. As shown in FIG. 2, the pipe 23 is fixed to the angle 22 so as to prevent the test liquid from spilling, and the first port 4 is opened to the atmosphere via the pipe 23 while the first port 4 is opened to the atmosphere. It is configured by closing the 2 port 5 with a stopper plug 24. In the durability test, a normal temperature test solution is supplied from the pipe 23 to the valve body 1 at atmospheric pressure, and then an operating fluid having an operating pressure of 0.5 MPa is supplied to and discharged from the drive unit 10 of the fluid control valve 8. The fluid control valve 8 is caused to perform a predetermined number of valve opening / closing operations at an operation interval of 2 seconds / valve closing time, and then the valve body 1 is detached from the fluid control valve 8 to the surface state of the valve seat 6 and the valve seat 6. This was done by examining the leakage state of the test solution. In addition, the durability test was done also about the valve body (untreated goods) 20 which has not performed the valve seat processing of this embodiment in the same procedure.

  As a result of this endurance test, the valve body 1 and the untreated product 20 do not change in the surface state of the valve seat 6 and the test liquid does not penetrate into the valve seat 6 even if the valve opening / closing operation is performed 3 million times. I was able to confirm that. From this, the valve seat 6 subjected to the valve seat processing of the present embodiment has a portion that is heated and melted by the heating member 14 even when the valve opening / closing operation is performed 3 million times, It was found that the durability was maintained without peeling at the boundary surface. Further, it has been found that the durability of the valve seat 6 is not lower than that of the untreated product 20 by the valve seat processing of the present embodiment. Therefore, the durability test proved that the valve seat processing by the heat treatment using the heating member 14 does not lower the sealing performance and durability.

<Metal ion dissolution test>
Next, a metal ion elution test for examining the effect of the valve seat processing of this embodiment on metal ion elution during fluid control will be described.
In the metal seal elution test, the valve seat (treated product) 1 subjected to the valve seat processing of the present embodiment and the valve body (untreated product) 20 not subjected to the valve seat processing of the present embodiment are analyzed. Whether or not metal ions eluted from 6 was examined.

  In the metal ion elution test, ultrapure water is sealed in the treated product (valve body) 1 and the untreated product (valve body) 20 and left for 30 minutes to elute the metal ions from the valve seat 6. At this time, the ambient temperature is set to room temperature. The test is performed in a clean room so that metal ions are not mixed into the ultrapure water from the outside of the valve body. When a predetermined time elapses after the ultrapure water is sealed, the metal ions contained in the ultrapure water in the valve body are analyzed. In this test, Li (lithium), B (boron), Na (sodium), Mg (magnesium), Al (aluminum), K (potassium), Ca (calcium), Cr (chromium), Mn (manganese), Fe It was examined how metal ions of (iron), Ni (nickel), Cu (copper), Zn (zinc), Sr (strontium), Ba (barium), and Pb (lead) were eluted. FIG. 10 shows an index of the results of the metal ion elution test. In FIG. 10, the index sum of the metal ions eluted from the untreated product valve body 20 is displayed to be 100.

As shown in FIG. 10, the metal ion elution index of the untreated product (valve body 20) is 22.0 for Na metal ion, 5.1 for Mg metal ion, 14.5 for K metal ion, and Ca. The metal ion was 7.2, the Ni metal ion was 1.0, the Zn metal ion was 50.2, the other metal ions were 0, and the total index was 100.
On the other hand, the metal ion elution index of the treatment product (valve body 1) is 27.9 for Na metal ion, 24.7 for K metal ion, about 10.6 for Ca metal ion, and 1 for Ni metal ion. The metal ion of Zn was 33.1, the other metal ions were 0, and the index total was 97.5.

  By this metal ion elution test, the valve body 1 subjected to the valve seat processing of the present embodiment can confirm the elution of Mg metal ions compared to the valve body 20 not subjected to the valve seat processing of the present embodiment. The type of eluted ions is the same except that it was not. Further, when the indices of metal ions (Na, K, Ca, Ni, Zn) eluted in common to the valve bodies 1 and 20 are compared, they are comparable. Therefore, when the valve body 1 is used in a semiconductor manufacturing line, it has been found that the influence of metal ions eluted from the valve seat 6 on the semiconductor manufacturing process is the same as that of the conventional product. This is presumably because the heating member 14 is made of the same material as the mold used for injection molding of the valve body 1 and can be regarded as equivalent to processing the seal surface 6a with the mold.

<Investigation test of the relationship between valve seat processing conditions and valve seat processing conditions>
Next, an investigation test of the relationship between the valve seat machining conditions and the valve seat machining state will be described. FIG. 11 shows the valve seat machining conditions. In FIG. 12, the image figure which shows the partial cross section of the valve seat state of the untreated goods 20 in which the valve seat process is not given is shown. FIG. 13 and FIG. 14 show an image diagram showing a partial cross-section of the valve seat state in which the valve seat processing has failed. FIG. 15 is an image diagram showing a partial cross section of the valve seat state in which the valve seat processing has been successfully performed.
In the valve seat processing, the load for pressing the valve seat 6 against the heating member 14, the heating temperature of the heating member 14, and the heating time for heating the valve seat 6 are processing conditions. Since the load that presses the valve seat 6 against the heating member 14 is determined by its own weight, the processing conditions that need to be set are the heating temperature of the heating member 14 and the heating time of the valve seat 6. Therefore, an experiment was conducted to examine the state of the valve seat 6 when the valve seat machining was performed on the valve seat 6 of the valve body 1 made of PFA while changing the heating temperature of the heating member 14 and the heating time of the valve seat 6.

  As shown in FIG. 12, in the untreated product 20 in which the valve seat processing is not performed on the valve seat 6, a weld line P <b> 11 is formed on the seal surface 6 a of the valve seat 6, and a molding burr is formed on the edge portion of the valve seat 6. A molding defect has occurred on the seal surface 6a, such as the occurrence of P12.

First, the heating time for pressing the valve seat 6 against the heating member 14 by the dead weight of the valve body 1 is fixed to 8 seconds, and the heating temperature of the heating member 14 is changed to observe the valve seat processing state. The results of examining the influence of the heating temperature of the member 14 on the valve seat processing will be described.
As shown in FIG. 13, when the heating member 14 is heated to the lower limit (305 ° C.) of the PFA melting temperature range and the valve seat 6 is pressed against the heating member 14 for 8 seconds as indicated by Y <b> 1 in FIG. 11, The weld line P11 cannot be completely filled with the molten resin, and a shallow and small recess P11 ′ remains on the seal surface 6a. Further, the molding burr P12 was sufficiently soft and could not be crushed, and a small convex portion P12 ′ remained on the edge portion of the seal surface 6a. Therefore, under this processing condition, the resin on the seal surface 6a cannot be melted so as to have sufficient fluidity, and the molding defects P11 and P12 cannot be eliminated.
On the other hand, as shown by Y2 in FIG. 11, when the heating member 14 is heated to the upper limit value (315 ° C.) of the melting temperature range of PFA and the valve seat 6 is pressed against the heating member 14 for 8 seconds, it is shown in FIG. Thus, as shown in P41, the edge portion of the valve seat 6 was melted, the seal area of the seal surface 6a was reduced, and furthermore, a square protrusion was formed on the side surface of the valve seat 6. This is considered to be because the surface temperature of the valve seat 6 was heated to such an extent that the shape could not be maintained, and the shape of the edge portion could not be maintained. Reduction of the seal area is a problem because the desired sealing performance cannot be obtained, and the angular protrusions may be peeled off from the valve seat 6 during fluid control and become particles.
Furthermore, as shown by Y3 in FIG. 11, when the heating member 14 is heated to an intermediate value (310 ° C.) of the melting temperature range of PFA and the valve seat 6 is pressed against the heating member 14 for 8 seconds, it is shown in FIG. Thus, the molding defects P11 and P12 shown in FIG. 12 could be eliminated while the valve seat 6 maintained its shape.
From the above results, when the time for pressing the valve seat 6 against the heating member 14 is fixed to 8 seconds, when the heating temperature of the heating member 14 is set to an intermediate value of the melting temperature range of PFA which is the material of the valve body 1, It has been found that the flatness of the valve seat 6 can be obtained by eliminating the molding defect.

Next, by fixing the heating temperature of the heating member 14 to an intermediate value (310 ° C.) of the melting temperature range of PFA, changing the time for pressing the valve seat 6 against the heating member 14, and observing the valve seat processing state The results of examining the effect of heating time on valve seat processing will be described.
As shown in Y4 of FIG. 11, when the valve seat 6 was pressed against the heating member 14 for 15 seconds, the edge portion of the valve seat 6 was melted as shown in P41 of FIG. It is considered that this is because the time for pressing the valve seat 6 against the heating member 14 is too long, the surface temperature of the valve seat 6 is heated to such an extent that the shape cannot be maintained, and the edge portion has melted.
On the other hand, when the valve seat 6 is pressed against the heating member 14 for 10 seconds or 5 seconds as shown in Y5 and Y6 of FIG. 11, as shown in FIG. The molding defects P11 and P12 could be eliminated.
From the above results, when the heating temperature of the heating member 14 is fixed to an intermediate value in the melting temperature range of PFA that is the material of the valve body 1, the heating time for pressing the valve seat 6 against the heating member 14 to heat is 5 It has been found that a range of not less than 10 seconds and not more than 10 seconds is suitable.

  When the above test results are summarized, as shown in FIG. 11, a graph X1 indicating the boundary where the edge portion of the valve seat 6 melts and a graph X2 indicating the boundary where the molding defect is eliminated are obtained. From this test result, when the valve seat 6 is pressed against the heating member 14 by its own weight, the valve seat processing conditions are set such that the heating time for heating the valve seat 6 is in the range of 5 seconds to 10 seconds. It is preferable to set the heating temperature of the member 14 within the range of the intermediate value of the melting temperature range of the material of the valve body 1 ± 30% of the temperature difference between the upper limit value and the lower limit value of the melting temperature range. It was supported.

<Effect>
As described above, in the valve seat processing method of the above-described embodiment, when the flat contact surface 14b of the heated heating member 14 is pressed against the seal surface 6a of the valve seat 6, the seal surface 6a is melted to heat the heating member. 14 is flattened along the contact surface 14b, and molding defects such as the weld line P11 and the molding burr P12 are eliminated. When the heating member 14 is separated from the seal surface 6a, the seal surface 6a is solidified and becomes a smooth flat surface. In such a valve seat processing method, no stuffiness is generated on the seal surface 6a. Therefore, when the fluid control valve 8 using the valve body 1 having the valve seat 6 processed by the valve seat processing method performs fluid control. The gusset of the seal surface 6a is not peeled off from the seal surface 6a and becomes particles. Therefore, according to the valve seat processing method, the valve body 1 and the fluid control valve 8 of the above embodiment, the flatness of the valve seat 6 can be obtained so that particles are not generated.

  In the valve seat processing method of the above embodiment, since the material of the heating member 14 is the same material as the mold used when the valve body 1 is injection molded, the sealing surface 6a of the valve seat 6 is heated by the heating member 14. In this case, metal ions different from the mold are not injected into the valve seat 6. Therefore, according to the valve seat processing method of the above-described embodiment, when the valve body 1 is used for fluid control, ions different from the mold are eluted from the valve seat 6 and adversely affect the manufacturing process of products such as semiconductors. Can be prevented.

  In the valve seat processing method of the above embodiment, since the processing temperature of the heating member 14 is controlled within the melting temperature range of the material forming the valve seat 6, the seal surface 6a of the valve seat 6 is the contact surface of the heating member 14. The heat is transferred from the melt and melted so as to have fluidity, so that the molding defects are easily eliminated and the surface becomes flat.

  In the valve seat processing method of the above embodiment, the valve body 1 is placed on the contact surface 14 b of the heating member 14 via the valve seat 6, and the sealing surface 6 a of the valve seat 6 is attached to the heating member 14 by its own weight. Therefore, the load that presses the seal surface 6a of the valve seat 6 against the contact surface 14b of the heating member 14 can be stabilized, and the flatness of the valve seat 6 can be stably brought out.

In addition, this invention is not limited to the said embodiment, Various application is possible.
For example, in the above embodiment, the valve body 1 is used for the air operated fluid control valve 8 having a diaphragm valve body (not shown). However, the valve body 1 may be applied to other types of valves such as poppet valves, motor valves, electromagnetic valves, and vacuum valves. Also good.
For example, in the above embodiment, the valve seat 6 is provided integrally with the valve body 1, but the valve seat 6 may be separate from the valve body 1.
For example, in the above embodiment, the heating member 14 is heated from the inside of the heating member 14 by the rod heater 15, but the heating member 14 may be heated from the outside of the heating member 14 by winding a heater belt around the heating member 14.
For example, in the above-described embodiment, the heating member 14 has a rectangular parallelepiped block shape, but the heating member may have another shape such as a polyhedral block shape, a plate shape, or a rod shape.

(Second Embodiment)
<Configuration of heating member>
In the second embodiment, the shape of the heating member 50 is different from that of the heating member 14 in the first embodiment in that a valve seat forming recess 51 is formed on the contact surface 50b. On the other hand, there is no difference between other structures. Therefore, the structure of the valve seat forming recess 51 on the contact surface 50b different from the first embodiment will be described with reference to FIGS. 20 to 27, and the same reference numerals as those of the first embodiment will be used for the other structures. I will omit the explanation.

FIG. 20 is a schematic configuration diagram of the heating member 50.
As shown in FIG. 20, a recess-shaped valve seat forming recess 51 along the valve seat 60 is formed on the contact surface 50 b of the heating member 50.
Specifically, the surface layer surface 61 of the valve seat 60 has a flat valve body contact surface 61b that contacts the valve body, and a tapered surface 61a that is inclined downward on the valve body contact surface 61b. A valve seat end 61c is formed at the joint between the valve seat contact surface 61b and the tapered surface 61a.
The valve seat formation recess 51 includes a flat valve body contact formation surface 51b that contacts the valve body contact surface 61b, a taper formation surface 51a that contacts the taper surface 61a, and a valve seat end that contacts the valve seat end 61c. It has the part formation surface 51c.
Since the valve seat forming concave portion 51 has a concave shape along the valve seat 60, the shape of the surface layer 61 of the resin valve seat 60 is changed to a valve by pressing the heated valve seat forming concave portion 51 against the valve seat 60. The shape of the seat forming recess 51 is transferred. Therefore, the smoothness of the surface layer 61 of the valve seat 60 can be greatly improved. At the time of transfer, the surface roughness of the valve seat forming recess 51 is transferred, so that it is also necessary to keep the surface roughness of the valve seat forming recess 51 smooth.
In addition, since the size of the surface layer 61 of the valve seat 60 can be managed by the size of the valve seat forming recess 51, a fluid control valve having the valve seat 60 with high dimensional accuracy easily and inexpensively is provided. Can do.

<Valve seat processing method>
In FIG. 25, the schematic block diagram of the heating member 14 in 1st Embodiment is shown. FIG. 26 shows a partially enlarged view of the valve seat 60 after the valve seat processing is performed by the heating member 14 in FIG.
FIG. 27 is an electron micrograph (magnification: × 1000) obtained by partially photographing the outer edge portion of the valve seat when the valve seat is processed by the heating member 14 in the first embodiment. In this electron micrograph, the valve seat 60 is taken from directly above the surface layer 61. FIG. 27 is a diagram corresponding to the electron micrograph shown in FIG.
As shown in FIG. 28, the surface layer surface 61 of the valve seat 60 after the valve seat 60 is processed by the heating member 14 in the first embodiment is flush with the valve seat abutting surface 61b by crushing the molding burr. It is solidified.
Therefore, since the valve seat abutting surface 61b is flush with the valve seat abutting surface 61b, the valve seat abutting surface 61b is smooth and has no stuffiness.

However, although the molding burr is crushed by the heating member 14 and becomes flush with the valve seat abutment surface 61b, the crushing molding burr is as shown in FIG. In addition, there is a possibility that minute burrs P51 and P52 may remain in the valve seat end portion 61c in a position parallel to the valve seat abutment surface 61b. In FIG. 26, the fine burrs P51 and P52 are illustrated so that they can be easily understood, but can be actually confirmed by a microscope or the like.
The reason is that, in the case of the heating member 14 having a flat surface improvement as shown in FIG. 25, the heating burr 14 is pressed against the valve body abutting surface 61b from the vertical direction to eliminate the molding burr. Can do. However, the heating member 14 is pressed against the tapered portion 61a from a substantially perpendicular direction. Therefore, there is a possibility that minute burrs P51 and 52 that are continuous from the valve seat contact surface 61b and parallel to the valve seat contact surface 14b may occur at the valve seat end portion 61c that contacts the taper portion 61a.
If the minute burrs P51 and 52 remain, there is a problem that they may be turned up and generate particles.

  In the second embodiment, after the heating member 50 shown in FIG. 20 is lowered and brought into contact with the valve seat 60, the heating member 50 continues to descend, and the valve body 1 is placed on the heating member 50 via the valve seat 60. Move to the valve seat machining position away from the body 1. As a result, the surface 60 of the valve seat 60 is pressed against the valve seat forming recess 51 of the heating member 50 by the weight of the valve body 1.

The heating member 50 is heated to a set temperature (here, 310 ° C.) by the heater 15. Therefore, the surface layer surface 61 pressed against the valve seat forming recess 51 is transferred with heat from the valve seat forming recess 51, and the surface layer surface 61 is melted. When the surface layer surface 61 is melted, it becomes flat following the valve seat forming recess 51 of the heating member 50, and the molding defect P12 as shown in FIG. 6 in the first embodiment can be eliminated. Further, since not only the plane improvement but also the entire valve seat surface 61 can be improved, the minute burrs P51 and P52 as shown in FIG. 28 do not occur.
When the heating member 50 is separated from the surface layer surface 61, the entire surface layer surface 61 is solidified and becomes a smooth flat surface. Therefore, the molding defect P12 and the minute burrs P51 and P52 do not occur on the surface layer 61. When the fluid control valve using the valve body 1 having the valve seat 60 processed by the valve seat processing method performs fluid control, the surface layer 61 does not have a blur, so that the strip is peeled off from the surface layer 61. And never become particles.
Therefore, according to the valve seat processing method, the valve body 1 and the fluid control valve of the above aspect, the smoothness of the valve seat 60 can be obtained so that particles are not generated.

FIG. 21 shows an electron micrograph (magnification: × 1000) (1) in which the outer edge portion of the valve seat after the valve seat processing is partially photographed. FIG. 22 shows a view corresponding to the electron micrograph shown in FIG. FIG. 23 shows an electron micrograph (magnification: × 1000) (2) in which the outer edge portion of the valve seat after the valve seat processing is partially photographed. The electron micrographs of FIGS. 21 and 23 are photographs of the valve seat 60 taken from the valve seat contact surface 61b side. FIG. 24 shows a view corresponding to the electron micrograph shown in FIG.
Specifically, in the valve seat 60, the valve seat taper portion 61a, the valve seat contact surface 61b, and the valve seat end portion 61c shown in the electron micrograph of FIG. 22 corresponding to FIG. Yes. Further, the valve seat taper portion 61a, the valve seat contact surface 61b, and the valve seat end portion 61c shown in the electron micrograph of FIG. 24 corresponding to FIG. 23 are smooth.
That is, the surface layer surface 61 pressed against the valve seat forming recess 51 is transferred by heat from the valve seat forming recess 51, so that the surface layer surface 61 melts and becomes flat following the valve seat forming recess 51 of the heating member 50. Smooth as a whole.
The valve body 1 processed in this way forms a fluid control valve 8 by sandwiching a diaphragm valve body (not shown) between the drive unit 10 and is used for fluid control. As shown in FIGS. 21 to 24, the valve body 1 has a smooth surface 61 of the valve seat 60 and no mussels. Therefore, the valve body 1 can be opened or closed by contacting or separating the diaphragm valve body. Even if it is repeated, no particles are generated from the valve seat 60.

1 Valve body 6 Valve seat 6a Seal surface 8 Fluid control valve 14 Heating member 14b Contact surface

Claims (7)

In the valve seat processing method for obtaining the flatness of the resin valve seat of the valve body,
A valve seat machining method, comprising: pressing a flat contact surface of a heated heating member against a seal surface of the valve seat; and then separating the heating member from the seal surface. In the valve seat processing method according to claim 1,
A valve seat forming concave portion having a concave shape along the valve seat is formed on the contact surface,
The valve seat processing method characterized by this. In the valve seat processing method according to claim 1 or 2,
The valve seat processing method, wherein the heating member is made of the same material as that of a mold used when the valve body is injection-molded. In the valve seat processing method according to any one of claims 1 to 3,
A valve seat processing method, wherein a heating temperature of the heating member is controlled within a melting temperature range in which a material forming the valve seat is melted. In the valve seat processing method according to any one of claims 1 to 4,
A valve seat processing method, wherein the valve body is placed on a contact surface of the heating member via the valve seat.   A valve body having a valve seat processed by the valve seat processing method according to any one of claims 1 to 5. A valve body having a valve seat processed by the valve seat processing method according to any one of claims 1 to 5;
A fluid control valve, comprising: a drive unit coupled to the valve body and configured to contact or separate the valve body from the valve seat.