JP5286330B2 - Sealing method for resin diaphragm - Google Patents

Description

  The present invention relates to a method for sealing a resin diaphragm used for a valve or the like.

  Semiconductor production lines often use powerful acids and high-temperature fluids that are powerful drugs, and pipes, sensors, and valves require chemical resistance and other performance, so diaphragms for moving parts to isolate fluids In addition, for example, as in Patent Document 1, most use fluororesin.

  However, the fluororesin is almost impossible to be bonded and is manually welded by a technician. In addition, the generation of toxic gases such as fluoric acid gas due to heating is also considered, and it is necessary to consider the working environment for protecting the health of workers.

  Although the fluororesin is sometimes welded by irradiation with an electron beam at a high temperature as in Patent Document 1, for example, high skill is required, and secondary processing may be required to adjust the appearance after welding. . Also, it is extremely difficult to weld thin objects such as diaphragms, and design ingenuity is required.

  Further, the seal of the conventional fluororesin valve body and diaphragm employs a sealing structure in which the diaphragm 1 is installed between the upper and lower housings 2 and 3 and tightened with a plurality of screws 4 or the like as shown in FIG. ing. That is, the sealing function is maintained by the repulsive force possessed by the fluororesin itself by means such as providing the V protrusion 5 and the groove 6 in the sealing portion.

  However, this structure basically has a permanent deformation due to temperature history in the constituent material, and a creep phenomenon in which the composition is deformed and the repulsive force is attenuated, the sealing function is deteriorated, and the internal fluid may be leaked. is there. In addition, since the sealing is performed by tightening with the screws 4, it is necessary to tighten the screws 4 evenly, requiring skill of an assembly operator, and high contact accuracy between the parts constituting the seal portion Is required.

JP 2006-105859 A

  An object of the present invention is to provide a resin diaphragm sealing method capable of solving the above-described problems and satisfactorily welding a fluororesin diaphragm to a fluororesin housing.

  In order to achieve the above object, a resin diaphragm sealing method according to the present invention comprises a resin diaphragm for welding a flange portion of a diaphragm made of non-melting fluororesin as well as a flange portion of a housing made of non-melting fluororesin. In this sealing method, a molten resin sheet made of a thermoplastic fluororesin is interposed between the two flange portions, and the non-welded surface side of the diaphragm has good thermal conductivity and is not heated by the laser beam and transmits the laser beam. An endothermic material is disposed, and a laser beam for heating is irradiated from the endothermic material side to melt the molten resin sheet and weld the flange portions.

  Further, the resin diaphragm sealing method according to the present invention is a resin diaphragm sealing method in which a flange portion of a housing made of thermoplastic fluororesin and a flange portion of a diaphragm made of non-melting fluororesin are welded. A heat-absorbing material that has good thermal conductivity and is not heated by the laser beam and transmits the laser beam is disposed on the welding surface side, and the flange portion of the housing is melted by irradiating the laser beam for heating from the heat-absorbing material side. The flange portions are welded together.

  According to the sealing method of the resin diaphragm according to the present invention, by heating with a laser beam, the diaphragm made of a fluororesin and the housing are reliably integrated by welding, no liquid leakage occurs, no generation of toxic gas, The reliability of the sealing function is increased.

1 is a cross-sectional view of a valve of Example 1. FIG. It is explanatory drawing of the welding method of Example 1. FIG. It is explanatory drawing of the welding method of Example 1. FIG. It is explanatory drawing of the welding method of Example 2. FIG. It is a graph at the time of welding modified PTFE. It is a graph in case modified PTFE is welded together via a molten resin sheet. It is sectional drawing of the conventional valve | bulb.

  The present invention will be described in detail based on the embodiment shown in FIGS.

  FIG. 1 is a sectional view of a valve using a fluororesin diaphragm. For example, it is made of thermoplastic fluororesin such as PFA (Tetrafluoroethylene Perflouroalkoxy vimyl ether copolymer), and non-melting fluororesin such as PTFE (Polytetrafluoroethylene) and modified PTFE between upper and lower housings 11 and 12 formed by injection molding. The diaphragm 13 which consists of is interposed. A driving rod 14 is formed integrally with the upper portion of the diaphragm 13, and a valve portion 15 is formed integrally with the lower portion. The valve portion 15 can be inserted into the hole portion 16 of the lower housing 12. In this case, there is no problem even if the upper housing 11 that does not require welding is made of non-melting fluororesin.

  A drive unit 17 is fixed above the upper housing 11, the tip of the drive rod 14 is connected to the drive unit 17, and the diaphragm portion 13 a at the center of the diaphragm 13 is movable up and down via the drive rod 14 by the drive unit 17. Has been. Since the diaphragm portion 13a is repeatedly bent during use, the diaphragm 13 is made of the above-described non-melting fluororesin and is formed by cutting out from the block body so that cracks and the like do not occur even when used repeatedly. Further, a flange portion 13b is provided around the periphery.

  FIG. 2 is an explanatory view when the diaphragm 13 is welded to the lower housing 12 which is a valve body. In the valve of FIG. 1, the lower housing 12 and the diaphragm 13 need to be adhered to each other by welding in order to seal the inside of the valve chamber 18. For example, a flange portion 13 b having a thickness of 0.3 mm is attached to the lower housing 12. For example, it overlaps on the flange part 12a of thickness 10mm. Furthermore, an annular endothermic material 19 having a thickness of, for example, 5 mm is also placed on the non-welded surface side of the flange portion 13b.

  Bolt holes 12b, 13c, and 19a are previously drilled in the flange portion 12a, the flange portion 13b, and the heat absorbing material 19, and the bolt holes 12b, 13c, and 19a are used as a reference for accurate positioning using a jig (not shown). Laminate and fix.

  The endothermic material 19 has a good thermal conductivity and needs to be a material that transmits laser light without being heated by the laser light. For example, zinc selenium, germanium, silicon, and the like are preferable.

  Then, as shown in FIG. 3, for example, the heating laser light L generated from the carbon dioxide laser light source is irradiated in an annular shape by scanning a plurality of times if necessary, and the flange portion 13 b of the diaphragm 13. And the flange part 12a of the lower housing 12 is heated. In addition, the intensity | strength is adjusted so that a laser beam may reach to the boundary part of the flange part 13b and the flange part 12a. The laser beam L may be scanned by rotating the laser light source or by rotating a jig to which the diaphragm 13 or the like is fixed, as long as relative scanning is possible.

  When the flange portion 12a made of a thermoplastic fluororesin reaches about 320 ° C. or more by the irradiation with the heating laser beam L, melting starts. As shown by the dot portion 20 in FIG. 2, a part of the melted flange portion 12 a also enters the flange portion 13 b of the diaphragm 13, and the two are welded in an annular shape.

  During this welding, the temperature rise on the endothermic material 19 side of the flange portion 13b of the diaphragm 13 is prevented by the endothermic material 19, and the flange portion 13b is not altered by heat. Further, the flange portion 13b is pressed by the endothermic material 19 so that the weld portion is not deformed and both are well welded, no secondary processing is required, and no toxic gas is generated.

  For example, when the diameter of the welded portion is about 20 mm, although it depends on the intensity and type of the heating laser beam L, a welded portion with a good finish can be obtained by circular scanning of the laser beam for about 120 seconds.

  The endothermic material 19 is removed from the lower housing 12 and the diaphragm 13 thus welded, and the flange portion 11a of the upper housing 11 is attached from above the diaphragm 13 as shown in FIG. For example, SUS bolts 21 are inserted into the four bolt holes 12 b and 13 c and the bolt holes 11 b of the upper housing 11 which are drilled in advance, and are fixed by the nuts 22. Thereby, the upper housing 11, the diaphragm 13, and the lower housing 12 are assembled as a unit. Further, the drive unit 17 is assembled on the upper housing 11 to complete the valve.

  For example, the fluid flows into the valve chamber 18 from the hole 16 of the lower housing 12 and flows out from the outlet 23 indicated by a dotted line, and the position of the valve 15 relative to the hole 16 is adjusted by the movement of the diaphragm 13 by the drive rod 14. And the flow rate is controlled.

  In the first embodiment, a thermoplastic fluororesin is used for the lower housing 12, but the thermoplastic fluororesin has an advantage that it can be molded by a mold, but has a disadvantage that the bending property is poor and the material cost is high.

  Therefore, in the second embodiment, the lower housing 12 is formed by cutting a non-melting fluororesin block material such as PTFE, preferably modified PTFE. As shown in FIG. 4, between the flange portion 13b of the diaphragm 13 made of non-melting fluororesin and the flange portion 12a of the lower housing 12, an annular shape made of thermoplastic fluororesin made of, for example, PFA having a thickness of 25 μm, for example. The molten resin sheet 24 is sandwiched. Further, an endothermic material 19 is disposed on the diaphragm 13 and fixed by a jig as in the first embodiment.

  In this state, when the laser beam for heating is irradiated relatively in an annular shape from the endothermic material 19 side and scanned, the molten resin sheet 24 that is easily melted as indicated by the dot portion 25 is melted, and the flange portion 12a and the flange portion 13b is bonded. In addition, the endothermic material 19 absorbs heat from the upper surface of the diaphragm 13 during the irradiation with the laser beam L, and the diaphragm 13 is prevented from being altered in the same manner as in the first embodiment.

  For example, although it is not possible to weld non-melting fluororesins of modified PTFE by heating laser light, the characteristics shown in FIG. 5 can be obtained, whereas when a PFA sheet is sandwiched between modified PTFE, Characteristics as shown in FIG. 6 were obtained. That is, FIG. 5 shows a result of welding the modified PTFE sheets having a thickness of 0.3 mm with a laser beam and conducting a tensile strength test, and fractured at a stress of 5.7 MPa at a strain of 1.5 mm. On the other hand, FIG. 6 shows a result when a molten resin sheet made of PFA having a thickness of 25 μm is sandwiched in a modified PTFE sheet having a thickness of 0.3 mm, and the stress is 10.6 MPa at a strain of 2.2 mm. It broke at.

  Further, the elongation using the molten resin sheet 24 is significantly increased even at the same breaking strength. Thus, it is confirmed that the welding between the modified PTFEs is inferior to the welding strength between the PTFEs via PFA. According to experiments, a thickness of the molten resin sheet 24 of about 25 μm is sufficient.

  That is, when the molten resin sheet 24 made of thin PFA is sandwiched between the diaphragm 13 made of modified PTFE and the lower housing 12 as in Example 2, the molten resin sheet 24 plays a role like an adhesive, Results with improved weld strength are obtained.

DESCRIPTION OF SYMBOLS 11, 12 Housing 13 Diaphragm 14 Drive rod 15 Valve part 19 Endothermic material 24 Molten resin sheet

Claims (5)

  In a sealing method of a resin diaphragm in which a flange portion of a diaphragm made of non-melting fluororesin is welded in the same manner as a flange portion of a housing made of non-melting fluororesin, melting made of a thermoplastic fluororesin between the two flange portions A resin sheet is interposed, an endothermic material that has good thermal conductivity and is not heated by laser light and transmits laser light is disposed on the non-welded surface side of the diaphragm, and a heating laser beam is irradiated from the endothermic material side. A method for sealing a resin diaphragm, comprising melting the molten resin sheet and welding the flange portions together.   In a sealing method of a resin diaphragm in which a flange portion of a housing made of thermoplastic fluororesin and a flange portion of a diaphragm made of non-melting fluororesin are welded, the non-welded surface side of the diaphragm has good thermal conductivity and is irradiated by laser light. A resin diaphragm characterized in that an endothermic material that transmits laser light without being heated is disposed, and the flange portion of the housing is melted by irradiating the heating laser light from the endothermic material side to weld the flange portions together. Sealing method.   3. The resin diaphragm sealing method according to claim 1, wherein the non-melting fluororesin is PTFE or modified PTFE.   3. The resin diaphragm sealing method according to claim 2, wherein the thermoplastic fluororesin is PFA.   The sealing method for a resin diaphragm according to any one of claims 1 to 4, wherein the laser beam for heating is irradiated while being moved relative to the flange portion.

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