Fluororesin molded body

Abstract

A fluororesin molded body used in a fluid device and having an annular sealing portion (10), wherein the sealing portion is composed of a protrusion (14) and a support portion (12) arranged in a direction in which the fluororesin molded body receives a compressive load when the fluororesin molded body is assembled in the fluid device.

Description

Technical Field

[0001] The present invention relates to a fluororesin molded body having a sealing portion. Background Art

[0002] In valve devices used in semiconductor manufacturing, etc., corrosive fluids such as ultrapure water and ozone water are used. Therefore, from the viewpoint of corrosion resistance, a sealing portion may be formed of a fluororesin.

[0003] For example, Japanese Patent Application Laid-Open No. 2015-94409 describes a technique in which a diaphragm of a valve device is made of fluororesin. The outer edge of the diaphragm is sandwiched between a holding portion constituting a part of an actuator portion and a diaphragm holding portion provided on a body.

[0004] When a sealing force required for sealing is applied to a sealing portion made of fluororesin, it is accompanied by not only elastic deformation but also plastic deformation. Therefore, unlike the case of rubber materials that do not undergo plastic deformation, it is not easy to maintain good sealing performance. Summary of the invention

[0005] The present invention is made to solve such a problem, and an object of the present invention is to provide a fluororesin molded article having a sealing portion capable of performing stable sealing for a long period of time.

[0006] A fluororesin molded body according to the present invention is used in a fluid device and has an annular sealing portion, wherein the sealing portion is composed of a protrusion and a support portion arranged in a direction in which a compressive load is received when the fluororesin molded body is assembled in the fluid device.

[0007] According to the fluororesin molded body, the sealing portion receives a compressive load in a predetermined direction, so the protrusion plastically deforms to fill the gap with the counterpart member, and the support portion elastically deforms to ensure sealing pressure based on its reaction force, thereby enabling stable sealing for a long period of time.

[0008] The sealing portion of the fluororesin molded article according to the present invention is composed of the protrusions and the support portions arranged in a direction in which the fluororesin molded article receives a compressive load when the fluororesin molded article is assembled in a fluid device, and thus can exhibit stable sealing properties for a long period of time.

[0009] The above-mentioned objects, features, and advantages will be easily understood by the following description of the embodiments described with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a cross-sectional view of the sealing portion according to the first embodiment of the present invention.

[0011] Figure 2 It is quite right Figure 1A diagram showing the height of the sealing portion before and after a compressive load is applied to the sealing portion and when the compressive load is released.

[0012] Figure 3 Based on measured data Figure 1 A graph showing the temporal change in the recovery rate of the sealing portion.

[0013] Figure 4 Based on measured data and speculation Figure 1 A graph showing the time-dependent change in the recovery rate of the sealing portion.

[0014] Figure 5 It is a cross-sectional view of a sealing portion according to a second embodiment of the present invention.

[0015] Figure 6 It is a cross-sectional view of a sealing portion according to a third embodiment of the present invention.

[0016] Figure 7 It is a cross-sectional view of a sealing portion according to a fourth embodiment of the present invention.

[0017] Figure 8 It means having Figure 6 A partial cross-sectional view of a device according to an application example of a fluororesin molded body for a sealing portion.

[0018] Fig. 9 yes Figure 8 Enlarged view of part A.

[0019] Fig.10 It means that Figure 5 and Figure 7 A partial cross-sectional view of a device showing an application example of a fluororesin molded article as a sealing portion in a combined form.

[0020] Fig.11 yes Fig.10 Enlarged view of part B. DETAILED DESCRIPTION

[0021] The fluororesin molded body of the present invention has an annular sealing portion. Here, "a fluororesin molded body having a sealing portion" includes, of course, a case where a sealing portion directly related to a sealing function constitutes a part of the fluororesin molded body, but also includes a case where the entire fluororesin molded body is substantially a sealing portion. As an example of the former, a diaphragm valve core whose outer periphery is fixed to a fluid device can be cited, and as an example of the latter, a so-called sealing ring can be cited.

[0022] Hereinafter, the sealing portion of the fluororesin molded article according to the present invention will be described with reference to the drawings, with reference to preferred embodiments thereof.

[0023] (First Embodiment)

[0024] Regarding the first embodiment of the sealing portion of the fluororesin molded article according to the present invention, refer to Figure 1 to Figure 4 Provide explanation.

[0025] exist Figure 1 The cross section of the sealing portion 10 formed in an annular shape is shown. The sealing portion 10 is composed of a support portion 12 and a protrusion 14 protruding from the support portion 12. The cross-sectional shape of the support portion 12 is a rectangle, and the cross-sectional shape of the protrusion 14 is an isosceles triangle with the base placed on one side of the rectangle. In the following, for convenience, the sealing portion 10 is assumed to be fixed to an annular mounting groove (not shown) provided in the fluid device for description.

[0026] When the sealing part 10 is fixed to the mounting groove, it receives a compressive load in the direction in which the support part 12 and the protrusion 14 are arranged, that is, in the AA direction. When the sealing part 10 receives the compressive load, it deforms in a manner accompanied by elastic deformation and plastic deformation. At this time, the plastic deformation area is mainly concentrated on the protrusion 14. The support part 12 is plastically deformed in the area close to the protrusion 14, and is elastically deformed in part of the other area.

[0027] The protrusion 14 undergoes plastic deformation, whereby the gap between the protrusion 14 and the counterpart member (not shown) is completely filled along the annular line at the top of the protrusion 14. In other words, the top of the protrusion 14 is deformed to exactly match the surface shape of the counterpart member. Furthermore, since the protrusion 14 receives the elastic reaction force from the elastically deformed support portion 12, it is strongly pressed against the counterpart member, and a sealing effect based on a high surface pressure can be obtained using the annular line at the top of the protrusion 14 as a sealing line. In addition, in the initial state, a circular arc of about 0.5R can also be formed at the top of the protrusion 14.

[0028] In order to ensure the necessary sealing performance, the sealing part 10 must have a recovery performance of a predetermined value or more when the compressive load on the sealing part 10 is released. Furthermore, the recovery performance of a predetermined value or more must be maintained when the compressive load is released until a period of time at least equivalent to the service life has passed since the compressive load was applied. In addition, the sealing part 10 of a fluororesin molded body is installed and fixed in the installation groove only once, and the same sealing part 10 is not repeatedly installed and fixed multiple times.

[0029] The present applicant has studied the relationship between the recovery rate, which is an index indicating the recovery property, and the angle θ of the apex of the protrusion 14 and the change of the recovery rate over time. Figure 2As shown in FIG. 1 , the “recovery rate” is a value calculated using the following formula (1) by setting the height (length in the AA direction) of the sealing portion 10 before the compressive load is applied as H1, the height of the sealing portion 10 after the compressive load is applied as H2, and the height of the sealing portion 10 after the compressive load is released as H3. In addition, H3 is obviously larger than H2 and smaller than H1.

[0030] [Recovery rate] = (H3-H2) / (H1-H2) Formula (1)

[0031] The fluororesin molded body used as the test piece is an annular fluororesin molded body consisting only of a sealing portion 10, that is, a sealing ring, and the sealing portion 10 is composed of a support portion 12 and a protrusion 14. In the initial state, the height (H1) of the sealing portion 10 is 20 mm, and the height h of the protrusion 14 is 1 mm. In addition, regarding the angle θ of the vertex of the protrusion 14 having an isosceles triangle cross-sectional shape, three types of test pieces were prepared, which were 60 degrees, 90 degrees, and 120 degrees in the initial state.

[0032] Then, the test piece was placed in a fixture, and a compressive load was applied in the AA direction where the support portion 12 and the protrusion 14 were arranged, until the height (H2) of the sealing portion 10 became 19.5 mm. After being placed in this state for a predetermined time (hereinafter referred to as "placement time"), the test piece was removed from the fixture, and the height (H3) of the sealing portion 10 after one hour from the removal was measured. For the above three types of test pieces, the placement time was changed within a maximum range of 6900 hours (about 290 days) to obtain a large amount of measurement data.

[0033] Figure 3 and Figure 4 The graphs show the change of the recovery rate over time based on the recovery rate calculated or estimated from the measurement data. The horizontal axis of these graphs represents the standing time and the vertical axis represents the recovery rate, and the angle θ of the vertex of the protrusion 14 is used as a parameter. Figure 3 A curve based on data actually measured up to the maximum storage time of 6900 hours is plotted. Figure 4 A curve including an extended portion estimated when the storage time is extended to 10 years is plotted.

[0034] like Figure 3 As shown in FIG. 1 , the recovery rate decreases with the passage of time. The rate of decrease in the recovery rate is large at the beginning of placement, and then gradually decreases. In addition, when the angle θ of the vertex of the protrusion 14 becomes smaller (120 degrees → 90 degrees → 60 degrees), the recovery rate decreases, and the curve representing the time-dependent change of the recovery rate moves downward.

[0035] When the service life required for the sealing portion 10 is set to 10 years and the recovery rate for achieving the required sealing performance is set to 45% or more, according to Figure 4 It can be seen that the angle θ of the vertex of the protrusion 14 can be within the range of 90 to 120 degrees. When the angle θ of the vertex of the protrusion 14 exceeds 120 degrees, in addition to problems with sealing, according to stress analysis of the protrusion 14, no deformation occurs in the portion away from the contact point, resulting in waste of material.

[0036] Here, the "collapse rate" which is an index showing the degree of deformation due to the compressive load is calculated by the following formula (2) using the aforementioned H1 and H2.

[0037] [Collapse rate] = (H1-H2) / H1 Formula (2)

[0038] (H1-H2) is the so-called collapse amount. In the above-mentioned test example, the collapse rate is 2.5%.

[0039] When the shrinkage rate of the sealing part is too small, the plastic deformation for making the top of the protrusion 14 match the surface shape of the other member and the elastic deformation for pushing the top of the protrusion 14 to the other member are insufficient. When the shrinkage rate of the sealing part is too large, the internal stress becomes too large and the plastic deformation rate becomes high, and the recovery rate decreases. The shrinkage rate of the sealing part is preferably 1% to 3%.

[0040] (Second Embodiment)

[0041] Next, regarding the second embodiment of the sealing portion of the fluororesin molded article according to the present invention, referring to Figure 5 The sealing portion 20 of the second embodiment is different from the sealing portion 10 of the first embodiment in the shape of the support portion 22 .

[0042] exist Figure 5 The cross section of the sealing portion 20 formed in an annular shape is shown. The sealing portion 20 is composed of a support portion 22 and a protrusion 24 protruding from the support portion 22. The cross-sectional shape of the protrusion 24 is an isosceles triangle. In the support portion 22, grooves 26 and 28 are formed on both sides of the protrusion 24 in a manner adjacent to the protrusion 24.

[0043] The cross-sectional shape of the pair of grooves 26 and 28 is an isosceles triangle that is the same as the cross-sectional shape of the protrusion 24, and the predetermined surfaces 26a and 28a of the pair of grooves 26 and 28 are connected to the surface of the protrusion 24 in a coplanar manner. In addition, the width Wd of each groove 26 and 28 is equal to the width W of the protrusion 24.

[0044] The grooves 26 and 28 are formed on both sides of the protrusion 24, so that the protrusion 24 is easily deformed not only in the direction in which the compressive load acts but also in the direction perpendicular thereto, so that the deformation of the protrusion 24 is smoothly performed. In addition, when the support portion 22 is a flat surface, there is still a portion that does not contribute to the recovery, but by forming the grooves 26 and 28 on both sides of the protrusion 24, at least a part of the portion that does not contribute to the recovery can be eliminated, and material saving can be achieved.

[0045] In the present embodiment, the cross-sectional shape of the pair of grooves 26 and 28 is set to an isosceles triangle, but the cross-sectional shape may also be a semicircle, etc. In addition, the width Wd of the pair of grooves 26 and 28 is set to be the same as the width W of the protrusion 24, and the width Wd may be selected, for example, within the range of 0.5 to 1.5 times the width W of the protrusion 24. The angle θ of the vertex of the protrusion 24 is preferably set to 90 to 120 degrees as in the first embodiment.

[0046] (Third Embodiment)

[0047] Next, regarding a third embodiment of the sealing portion of the fluororesin molded article according to the present invention, refer to Figure 6 The sealing portion 30 of the third embodiment is different from the sealing portion 10 of the first embodiment in the shape of the support portion 32 and the like.

[0048] exist Figure 6 The cross section of the sealing portion 30 formed in an annular shape is shown. The sealing portion 30 is formed symmetrically in the upper and lower directions, and is composed of a support portion 32 and a pair of protrusions 34 and 36 protruding from the upper and lower sides of the support portion 32. The cross-sectional shape of the support portion 32 is a rectangular shape elongated in the upper and lower directions, and recesses 32a and 32b are formed on the left and right sides. The cross-sectional shape of the pair of protrusions 34 and 36 is an isosceles triangle, and the length L of the base is equal to the width W of the support portion 32.

[0049] In order to make substantially the entire support portion 32 a shape that facilitates elastic deformation, the width W of the support portion 32 is preferably set to 15% to 25% of the height H1 of the entire sealing portion 30 in the initial state. This can save material to the maximum extent.

[0050] By forming the recesses 32a and 32b on the left and right sides of the support portion 32, it is possible to save materials, and in addition, a self-sealing effect based on the fluid pressure acting on the recesses 32a and 32b can be expected. That is, the fluid pressure acting on the recesses 32a and 32b acts as a force toward the top of the pair of protrusions 34 and 36, and the pair of protrusions 34 and 36 can be further strongly pressed toward the counterpart member. The recess amount C is preferably set to 5% to 10% of the width W of the support portion 32. The angle θ of the apex of the protrusions 34 and 36 is preferably set to 90 to 120 degrees as in the first embodiment.

[0051] (Fourth Embodiment)

[0052] Next, regarding a fourth embodiment of the sealing portion of the fluororesin molded article according to the present invention, referring to Figure 7 The sealing portion 40 of the fourth embodiment is different from the sealing portion 10 of the first embodiment in that a plurality of protrusions are provided.

[0053] exist Figure 7 The cross section of the annular sealing portion 40 is shown. The sealing portion 40 is composed of a support portion 42 and two rows of protrusions 44 and 46 protruding from the support portion 42. The first protrusion 44 and the second protrusion 46 are isosceles triangles with the same cross-sectional shape and are arranged side by side so as to be in contact with each other.

[0054] In the initial state, the interval X between the first protrusion 44 and the second protrusion 46 is preferably set to 15% to 25% of the height H1 of the sealing portion 40. This can save material. In addition, the angle θ of the apex of each of the first protrusion 44 and the second protrusion 46 is preferably set to 90 to 120 degrees as in the first embodiment.

[0055] exist Figure 8 and Fig. 9 The example in which the seal ring 50 as a fluororesin molded body having the seal portion according to the third embodiment is applied to an electromagnetically operated two-way valve 52 is shown. The two-way valve 52 opens and closes a flow path formed inside a valve housing 60 by a valve core 58 integrally formed with a movable iron core 56 driven by a solenoid coil 54.

[0056] A cylindrical partition wall 64 is provided inside the metal valve housing 60 so as to intersect with the first port 62. A valve seat 66 is provided at the top end of the partition wall 64, with which the valve core 58 can abut, and an annular chamber 68 communicating with the first port 62 is formed around the partition wall 64. A cylindrical protruding wall 70 extending upward from the outer peripheral side of the annular chamber 68 is provided in the valve housing 60. The sealing ring 50 is mounted and fixed in a mounting groove 72 formed at the upper end of the protruding wall 70 and opening upward, and has the function of sealing the annular chamber 68 from the outside.

[0057] When the seal ring 50 is mounted and fixed to the mounting groove 72, first, the seal ring 50 is inserted into the mounting groove 72. At this time, the seal ring 50 protrudes upward from the mounting groove 72 by a predetermined length. Next, after the valve core 58, the movable iron core 56, the coil spring seat 74, and the coil spring 76 are arranged on the upper part of the partition wall 64 of the valve housing 60, the metal sleeve 80 having the flange portion 78 is fitted to the outer periphery of the movable iron core 56, and the cover body 82 is further fitted to the outer periphery of the protruding wall 70 of the valve housing 60.

[0058] Then, when the cover 82 is fixed to the valve housing 60 by bolts or other members (not shown), the seal ring 50 is pressed downward by the flange portion 78 of the sleeve 80 and is compressed and fixed in the mounting groove 72. At this time, the seal ring 50 is compressed to a collapse rate of 1% to 3%. The predetermined protruding length when the seal ring 50 is inserted into the mounting groove 72 is a length such that the collapse rate is 1% to 3%.

[0059] exist Fig.10 and Fig.11 An example is shown in which a valve housing (first body 90) of a fluororesin molded body having a sealing portion in the form of a combination of the sealing portion of the second embodiment and the sealing portion of the fourth embodiment is applied to a pneumatic valve device 92. Fig.11 yes Fig.10 , but for convenience, only the first body 90 is shown. The valve device 92 opens and closes the flow path formed inside the first body 90 by connecting the valve core 98 of the piston 94 driven by air pressure via the retaining portion 96.

[0060] A first port 102 located in the center and a second port 104 located outside the first port 102 are provided on a bottom wall 100 of the first body 90 formed in a cylindrical shape. An internal space 106 is formed inside the first body 90 to communicate the first port 102 and the second port 104 with each other. A valve seat 108 is formed at the peripheral edge of the first port 102 facing the internal space 106, with which the valve element 98 can abut.

[0061] An annular recess 110 is formed on the upper surface of the first body 90, and three rows of annular protrusions 112a, 112b, and 112c having isosceles triangle cross-sectional shapes are provided on the bottom surface of the recess 110. An annular first groove 114a having a semicircular cross-sectional shape is provided between the first protrusion 112a and the second protrusion 112b, and an annular second groove 114b having a semicircular cross-sectional shape is provided between the second protrusion 112b and the third protrusion 112c. In the first body 90, a portion located below the recess 110 constitutes a support portion.

[0062] The second body 116 disposed above the first body 90 is made of a resin or the like which is harder than the first body 90. The piston 94 is slidably provided inside the second body 116, and an annular protrusion 118 which fits into the recess 110 of the first body 90 is provided at the bottom of the second body 116. The second body 116 is fixed to the first body 90 using a member such as a bolt (not shown).

[0063] When the second body 116 is fixed to the first body 90, the three rows of protrusions 112a, 112b, 112c are pressed downward by the lower surface of the protrusion 118 of the second body 116. As a result, the three rows of protrusions 112a, 112b, 112c and the support portion are deformed to seal the internal space 106 of the first body 90 from the outside.

[0064] The fluororesin molded article according to the present invention is not limited to the above-described embodiments, and various modes can be adopted without departing from the gist of the present invention.

Claims

1. A fluororesin molded body used in a fluid device and having an annular sealing portion (30), characterized in that: The sealing portion is composed of a protrusion and a support portion (32) arranged in a direction to receive a compressive load when the fluororesin molded body is assembled in a fluid device. The protrusion is arranged on the upper and lower sides of the support, and depressions are formed on the left and right sides of the support. The width of the support is the same in the left and right directions except for the part where the depression is formed. The fluid pressure acting on the depression generates a force toward the top of the protrusion. When the fluororesin molded body is assembled in the fluid device, the shrinkage rate of the sealing portion is 1% to 3%. The height of the sealing portion before the compressive load is applied is defined as H1, and the height of the sealing portion after the compressive load is applied is defined as H2. The collapse rate is calculated by the following formula: [Collapse rate] = (H1-H2) / H1, The height of the sealing portion is the length of the sealing portion along the direction in which the compressive load is received. The cross-sectional shape of the protrusion is an isosceles triangle having two vertices on the support portion, and the angle of the vertex separated from the support portion is 90 degrees to 120 degrees.

2. The fluororesin molded article according to claim 1, wherein The width of the support portion is 15% to 25% of the height of the sealing portion. The width of the support portion is the radial length of the support portion along the sealing portion. The height of the sealing portion is the length of the sealing portion along the direction in which the compression load is received.

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