JP2014196832A - Polytetrafluoroethylene bellows and fluid pumping device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem that contamination of very small wastes and foreign matters ("particles" in the art) adversely influence various items such as product yield as semiconductor element integration increases in a semiconductor manufacturing device.SOLUTION: A bellows or a component constituting bellows having at least an inner surface that is a mirror surface and formed of PTFE, and a fluid pumping device are provided.

Description

  The present invention relates to a bellows made of polytetrafluoroethylene (hereinafter, “polytetrafluoroethylene” is abbreviated as “PTFE”), and a fluid pumping device using the bellows.

The bellows must be made of a material that can withstand the liquid circulating in the pump system in which it is used. For example, in the field of using various chemical solutions such as semiconductor manufacturing equipment, the material can withstand all of these chemical solutions. Then, it is unthinkable except PTFE. Further, since the bellows repeatedly bends, it must be made of a material having high bending resistance. In this respect, PTFE is outstanding. However, a polymer melt having extremely poor fluidity, such as PTFE, that is, a polymer melt having a high melt viscosity is made into a bellows shape by a general molding method such as an injection molding method, an extrusion molding method, or a transfer molding method. It was practically impossible. Even if a product having such a shape is produced, a product having a very large molding strain at the time of fluid molding is produced due to flow resistance, and it cannot be used for a bellows that requires repeated bending. Therefore, conventionally, it has been formed by machining with a lathe from a round bar-shaped block body. This point is described in, for example, Patent Document 1 and Patent Document 2 below.
JP 2001-193836 A No. 8-5417

  Thus, in the world of bellows, PTFE is outstanding in terms of material. However, since it is formed by mechanical cutting, it brings various problems to the application fields used as described below. I came.

  One problem occurs, for example, in semiconductor manufacturing equipment. As the degree of integration of semiconductor elements increases, a mixture of minute dust and foreign matters (hereinafter referred to as “particles”) causes various problems. Even if the size is smaller than the width of the circuit, particles on the circuit line can cause a significant decrease in production yield in all processes such as resist coating, development, etching, and resist stripping. This is because it causes deterioration of quality during use.

  As a result of the inventor's research, it was found that such a particle generation source is a bellows produced by cutting from PTFE. This point will be described in detail as follows. It is well understood by microscopic observation of the state of mechanical cutting, but at the same time a cutting trace groove is formed by the tip of the bite, and at the same time, cocoon-like lint and scaly slices that take into account the PTFE peculiar thread effect are infinite. Many are formed. Among these, the cocoon-like lint is also called “fluffing”, one end of the lint is free and the other end is connected to the molded product. In addition, when the scale-like slices are observed with a microscope, they are wrinkled and, like lint, one end is free and the other end is connected to the molded product, and the other end is also connected to the molded product. , There are some that are separated from the molded product. The lint and scaly slice should originally be cut off from the cutting point, but are not cut off and remain connected at that position. These lint and scale-like pieces remain on the bellows as a molded product for a certain period of time against the fluid flow in the pump. It is separated from the bellows without resisting and becomes particles. The size of the lint and scaly slices is due to the cutting process, so there is a considerable width, but the thickness of the lint is about 10 to 20 μm for the larger ones that can be seen with a microscope. The length of the yarn waste is about 100 to 800 μm. Moreover, the width | variety of a scale-like section is about 5 micrometers, and the length of a section is about 20-40 micrometers. There are many smaller ones. Even if an expensive filter is used on the discharge side in order to avoid mixing such particles into the product, there are particles that pass through them.

  Another problem is that the groove marks formed by machining with lint and scaly do not become particles, but in a system where ultrapure water circulates in the pump, the water is ultrapure water. Therefore, it was found that it is a cause of secondary contamination as a source of microorganisms. Since ultrapure water is pure water and is not sterilized, it is a source of microorganisms. Similarly, the groove-like unevenness inside the pipe of the ultrapure water production line is also a source of microorganisms.

The subject of this invention is providing the bellows which solves the said subject, and the fluid pumping apparatus using the same.

The present invention is a bellows or a part constituting a bellows having at least an inner surface made of PTFE having a mirror surface.

  Here, the “mirror surface” is glossy with no irregularities observed with the naked eye. Preferably, metal gold having a surface finish of 0.1-S to 6-S based on JIS B0601, more preferably 0.1-S to 0.8-S, and buff finish and lapping finish. It means a state in which PTFE is melted and pressure-bonded and transferred to the inner surface of the bellows using a mold. Therefore, 1 μm or less can be expected as the roughness range.

Moreover, this invention is the components which comprise the said bellows or bellows which are observed with a microscope and do not have a lint and a scale piece.

Moreover, this invention is the components which comprise the said bellows or the bellows whose transmittance | permeability of visible light in thickness 1mm is 50% or more.

Moreover, this invention is the components which comprise the said bellows or bellows which are screw types.

Further, the present invention is a fluid pressure feeding device using the bellows.

The bellows according to the present invention has a mirror inner surface, and unlike the PTFE bellows obtained by the cutting process, it is possible to obtain a product in which the lint and scaly slices that cause the generation of particles are not observed by microscopic observation.

The bellows according to the present invention is about 100 times more durable than a bellows made of a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin.

  The fluid pumping device according to the present invention is one that does not generate particles due to the bellows, and particularly when used in combination with a non-contact valve, one that does not cause the generation of particles from the fluid pumping device is obtained.

  Hereinafter, some embodiments of the present invention will be described based on the drawings.

[Method of forming a bellows by molding a preform]
One embodiment is a method of making a preform using a so-called molding powder of PTFE as a starting material, and making a bellows based on the preform. A known method is applied to the preform, and the preform is made through a preforming step and a primary firing step.

(Preliminary molding process)
Since PTFE has extremely high melt viscosity and poor fluidity, the shape of the preform can be deformed by subsequent melt-pressure molding, and can easily be bellows or bellows in various steps after melt-pressure molding. A shape that can be formed into a part is preferably selected. In the bellows, a cylindrical or beaker-shaped preform is preferable. Here, a case where a cylindrical preform is made will be described. Preliminary molding is molding using a hydraulic molding die. Specifically, a sealed space is formed by a cylindrical external mold and an upper mold and a lower mold that block both ends of the cylindrical external mold. A concentric outer core mold and a cylindrical core mold having a mirror-finished surface are disposed in the space. A cylindrical preform is formed in a gap provided between the outer mold and the core mold. Here, the outer mold is, for example, a bag-like rubber elastic body in which a liquid is put, and the gap between the cylindrical outer mold, the upper mold, and the lower mold can be eliminated and sealed. it can. The inner side of the outer mold is preferably made of a smooth surface. Further, the inner mold need not be made of metal, and may be ceramics, for example. While removing the upper mold and applying vibration to the gap, pre-pressurization of about 100 kg / cm ² is performed and a predetermined amount of PTFE molding powder is sealed, and a hydraulic pressure of 100 to 200 kgf / cm ² is filled in the outer mold. To make a so-called braided PTFE cylinder.

(Primary firing process)
The braided PTFE cylindrical material is heated in an electric furnace or an inert gas hot air furnace such as N ₂ at 340 to 400 ° C. which is higher than the melting temperature of PTFE 327 ° C. and lower than 425 ° C. which is a temperature at which large thermal decomposition does not start. Bake for 1 minute to 1 hour. At that time, a SUS holder is effective for preventing deformation. In this process, the molding powders are fused together, so-called voids are removed. After this, it is cooled.

(Sliding Plate Molding; SPM system)
The thus obtained preformed PTFE cylindrical product is placed between a core and a movable outer mold and subjected to compression molding to obtain a bellows. In compression molding, the stationary core may be generally symmetrical with respect to the central axis, and the material is usually a metal, particularly a metal that is corrosion resistant to fluorine and hydrofluoric acid. Ceramics, high-tensile carbon and clay may be fired. The movable outer die and the pushing outer die are made of a plurality of tough and hard plate-like metals, especially metals that are corrosion resistant to fluorine and hydrofluoric acid. The pressure compression molding is performed while applying an overall uniform pressure to the PTFE melt between the core and the melt. At the beginning and end of the molding process, the volume surrounding the core varies from large to small. Hereinafter, this molding method is referred to as “Sliding Plate Molding” or S. P. This will be referred to as M system. The bellows can be regarded as a combination of several single bellows. First, a method for preparing several single bellows and manufacturing a predetermined length of bellows will be described first.

  FIG. 1 is a perspective view showing a state before the manufacture of a single bellows, and a part surrounding the core 1 is partially cut away. FIG. 2 is a partial top view of FIG. Only the upper part of the top view is shown, and the others are omitted because they are symmetrical. As shown in FIGS. 1 and 2, the surface opposite to the outer mold has one peak 1p, and the mirror-finished one-core making core 1 is installed at the center, and in order toward the outside, Cylindrical inner heater 2 (not shown in FIG. 2), PTFE cylindrical object 3, cylindrical outer heater 4 (not shown in FIG. 2), movable divided into a plurality in parallel to the central axis of the core The number of outer molds 5a to 5h and the same number of movable outer molds 6a to 6h as the outer molds divided in the same direction are arranged concentrically with the core 1. Of these, the outer molds 5a to 5h and the booster outer molds 6a to 6h each have one peak part 5ap to 5hp and 6ap to 6hp, and the divided sides of the outer molds 5a to 5h. Each of the outer periphery of each of the outer peripheral molds 6a to 6h for each of the boosters overlaps with the periphery of the divided side and is movable while being slid and mutually melted. The diameters of the circles formed by the molds 5a to 5h and 6a to 6h are reduced, and when the cylindrical object 3 is melted, both of the outer molds 5a to 5h and 6a to 6h are prevented from leaking out. The structure is such that there is always no gap between the molds even when sliding. FIG. 3 is a view of the state after melt-compression molding as viewed from the same direction as FIG. 2, but is an overall view different from FIG. As described above, the pushing outer molds 6a to 6h finally move to the outside of the outer molds 5a to 5h, and only the outer molds 5a to 5h surround the outer periphery of the molded product. Yes.

  Each of the outer molds 5a to 5h and the booster outer molds 6a to 6h is composed of a plurality of molds. The larger the number, the smoother the mutual sliding is. It is necessary to satisfy the following requirements between the central angle α of the circular arc formed by and the central angle β of the circular arc formed by one booster outer die.

  For example, in the case shown in FIG. 2, the center angle α of the arc formed by one outer mold 5a is 24 ° when calculated from the figure. β is {360− (24 × 8)} / 8 = 21 ° because the number of outer molds for boosting is eight. Therefore, since the above-described conditions are satisfied, the slides are performed smoothly. On the other hand, when the number of each of the outer mold and the booster outer mold is four, although not shown, α is 42 ° and β is 48 °, which does not satisfy the above conditions.

  Further, in order to make this slide smooth, a heat-resistant lubricant may be interposed between both molds. Moreover, in order to prevent generation | occurrence | production of an unnecessary bowl-shaped part in a molded object, you may interpose a heat-resistant slip agent between the cylindrical body 3 made from PTFE, and the outer mold | dies 5a-5h. Further, the outer molds 5a to 5h and the booster outer molds 6a to 6h both reduce the diameter of the respective circles to be made while synchronizing with external force. The outer mold dies 5a to 5h are pushed by the pushing outer molds 6a to 6h. The outer heater 4 and the inner heater 2 are arranged with a gap so that the PTFE cylindrical body 3 sandwiched therebetween can be melted and extracted upward or downward. It is supposed to be heated. As described above, the heater is not a combination of the outer heater 4 and the inner heater 2, which are outside the core 1, but the inner heater 2 may be built in the core 1. Further, if possible in strength, the outer heater 4 may be incorporated in the outer molds 5a to 5h. Further, although not shown in the figure, there is a cooling device in the core 1 that can circulate a refrigerant to rapidly cool the molded product.

It manufactures as follows using such an apparatus. First, the heat-cooling 2 and 4 are ripened by energization, and the cylindrical body 3 made of PTFE is maintained at its shape and is set to 375 to 450 ° C., which is a temperature at which it does not undergo thermal decomposition and melts. Next, the heaters 2 and 4 are extracted, and are pushed toward the center with respect to each of the outer molds 5a to 5h by a pushing device (not shown) by hydraulic pressure or mechanical force from the outside through the outer pressing molds 6a to 6h. The external force 7 of 10 kgf / cm ² or more, preferably 20 kgf / cm ² or more, particularly preferably 50 kgf / cm ² or more is applied. By this external force 7, each of the pushing outer die dies 6a to 6h narrows the circle surrounded by the outer die dies 5a to 5h at a constant speed so as to be narrowed down while maintaining a concentric circle toward the core 1. At this time, the outer mold dies 5a to 5h pressed on both sides by the booster outer molds 6a to 6h are slid to the rear pusher molds 6a to 6h on both sides when viewed from the outside of the mold. It hides behind the outer molds 6a-6h for boosting both sides. In this process, the PTFE cylindrical body 3 is melt-pressed and compression-molded between the core 1 and the outer molds 5a to 5h. After the compression molding, the refrigerant is circulated in the core 1 so that the surface temperature of the core is 300 ° C. or lower, preferably 200 ° C. or lower, particularly preferably 150 ° C. or lower, and the molded product is rapidly cooled while being pressurized. . Such a rapid cooling and high transparency can be obtained.

(Bellows turning process)
The PTFE cylindrical body 3 is compression-molded as described above to form a single bellows base, but is wound around the core 1. 4a, 4b, 4c, and 4d are explanatory views showing a process of making a flange portion for removing the core 1 from the single bellows base 8, and FIG. 4b, FIG. 4c, and FIG. Indicates that the process proceeds. First, the upper part of the single bellows base material 8 is heated to 220 to 250 ° C. and is peeled off from the core 1 by thermal expansion, and is pressed back into the gap between the tip 8a of the bellows base material 8 and the core 1 for the first step. The tip 9a of the metal flange 9 is inserted (FIG. 4a). Subsequently, the bellows base material 8 having the flange portion 8b slightly turned over is obtained by moving the turned-up first-stage pressing metal flange 9 downward (FIG. 4b). The downward transition of the first-stage pressing metal flange 9 for turning is performed through the pressing bolts 13 while rotating the pressing disk-shaped flat plate 12 around the rotating support column 10 by the rotary handle 11. In order to further advance the turning, it is replaced with the turning-back second-stage pressing metal flange 14 instead of the turning-up first-stage pressing metal flange 9, and further, the rotating handle 11 is rotated in order to advance the turning. The turn-up further proceeds to turn-up 8c (FIG. 4c), and by further rotating the rotary handle 11, a single bellows base material 8 having a completely turned-up flange portion 8d is obtained (FIG. 4d). By performing the same operation on the lower part of the single bellows base material 8, the base body 8 having the flange portions 8d on the top and bottom is obtained. FIG. 5 is a longitudinal sectional view thereof. It is also possible to obtain several bellows instead of one. Further, the case where a cylindrical object is used as a preform has been described so far, but it is also possible to make a flange part on the upper part of a beaker using a beaker-like object.

(Bellows thinning adjustment process)
If there is unevenness in the thickness of the bellows, it will cause deformation such as swelling due to the internal pressure of the bellows from a thin part, causing damage to the bellows. Further, since the thickness spots cause deformation during the bending and stretching operation of the bellows, the thickness spots should be within ± 5%. Therefore, it is preferable to adjust the thickness unevenness by machining the outer side with a lathe using the core while copying the bellows around the core. Even if there is sticking or cutting marks on the outside, adjusting the thickness at this stage is not a major disadvantage in using the bellows.

(Core removal process)
FIG. 6 is a vertical cross-sectional view of the core removal device for explaining the core removal process. This figure shows a case where a five-belt base material 21 is made from a PTFE preform having a beaker shape, and a core is removed from a beaker having a flange portion at the wide mouth portion. The core punching device is roughly classified into a pressure-tight container 22 for lifting the core having airtightness shown in the upper part of the figure, and a core punching device support part 23 shown in the lower part of the figure. The core pulling-out pressure vessel 22 is an integral cylindrical object, and the upper O-ring 24 and the lower O-ring 25 maintain the internal airtightness, and the support member 26 positions the core. The flange portion 21c is held between the pressure pull-out container 22 for pulling out the core and the core punching device support portion 23 in a state where the five-belt base material 21 is still crimped to the core 27. A core pull-up rod 28 is fixed to the upper end of the core 27. Further, an internal pressure pressurizing device for increasing the internal pressure of the container 22 by an inert gas body such as N ₂ is connected to the core pull-out pressure resistant container 22 via an internal pressure pressurizing introduction port 29. A flange portion expansion device 30 is attached to the flange portion 21c. Inside this device 30, there is a claw-like chuck portion 31 that is actuated by hydraulic pressure, whereby the PTFE flange portion is expanded in the centrifugal direction by an external force 32 in the centrifugal direction to expand the PTFE flange portion.

Using such an apparatus, the core removal step is performed as follows. First, the bellows base 21 is uniformly heated to about 200 ° C. Since the thermal expansion coefficient of PTFE is 20 × 10 ⁻⁵ / ° C., the bellows base 21 is completely peeled from the core 27. Thereafter, if the internal pressure is set to, for example, 5 kgf / cm ² from the internal pressure pressurization introduction port 29, the average value 70φ is obtained by the hoop tension force when the diameter of the peak of the bellows is 80φ, the diameter of the valley is 60φ, and the wall thickness is 4mm. The bellows base material 21 expanded to about 100φ and integrated with the core 27 becomes an expanded bellows base material 33 having a size that can be removed without being blocked by the core 27. The core 27 is smoothly pulled up by the core pull-up force 34 by being expanded by an external force 32 in the centrifugal direction with respect to the flange portion 21c, for example, 11 kgf or more per 1 cm of the circumferential length of the flange portion 21c. In the case where the bellows base 21 is a cylindrical object, a flange portion may be formed at the lower portion and a flange portion expanding device may be attached thereto in the same manner. By the above, a bellows having five mountains was obtained. Since the number of peaks can be selected arbitrarily, the number of peaks is often sufficient, but if it is still insufficient, a welding process as described below is performed. Welding is performed by a known method of PTFE. A backup member made of light metal or engineering plastic other than PTFE may be attached to the flange portion formed by welding. After this, annealing is performed, but annealing is also performed by a known method, and the temperature is usually 230 to 290 ° C. FIG. 7 is a longitudinal cross-sectional view of a single bellows base material formed into a triple bellows by welding.

  Although the shape of the preform has been shown as a cylindrical or beaker-shaped bellows having several peaks, the shape of the preform is not limited to such a shape. For example, as a preform, a cylindrical product having a gently wavy surface instead of a curvature as that of a bellows is made, and a melt-formed product having at least an inner surface having a mirror surface is formed by a sliding plate molding method, and then pressure is applied from both ends thereof. And the molded product may be compressed to produce a bellows or a bellows part. In the case of a bellows, such an operation is performed after the core is removed. In the case of a bellows part, it may be welded after being compressed, or conversely welded and then compressed. In that case, it is preferable to heat. Moreover, since it may break depending on the method of pressurization when it is compressed at once, it is preferable to use gentle pressurization or multi-stage pressurization. In the case of this modification, the core can be easily removed. In the present invention, the preforms are referred to as “substantially cylindrical” and “substantially beaker”, respectively, in the sense that the preform includes such a cylindrical object having a gently wavy surface and a beaker object. Further, the shape of the preform may be an annular shape in which a hole corresponding to the bellows opening diameter is formed in the PTFE flat plate. FIG. 8 is an explanatory view showing the process of making a part that is divided at the top of a single bellows peak, and (a) is a cross-sectional view after a preform is melt-pressed. The cross-sectional view after turning it over is (b), and the cross-sectional view after welding it is (c). In this case, there is a disadvantage that the number of places to be welded increases, but there is also an advantage that it is not necessary to prepare a mold for sliding plate molding, and there is no need for an apparatus for removing the core mold. This method is not limited to the bellows, and can be applied to the manufacture of diaphragms for diaphragm pumps. Also, in (a), the bellows opening surface is perpendicular to the central axis, whereas as shown in (a ′), the bellows opening surface is formed obliquely with respect to the central axis and welded adjacent thereto. By forming the things to be matched to the inclination angle and sequentially welding them, a screw-type bellows that did not exist conventionally can be obtained.

(Equalized Pressure Molding; Method for producing screw-type bellows)
Furthermore, another modification is shown. Although it is common in that it is performed after a preform is made, this is another method that does not use the above-described sliding plate molding. It is another method for producing screw-type bellows. The screw-type bellows can be obtained by the above-described method, but this method is easier. FIG. 9 is a longitudinal sectional view when a preform is inserted into a mold apparatus for producing a screw-type bellows. The surface of the core 101 has such a shape that a screw-type bellows or a part thereof is formed by melt-pressing the molded product. A cylindrical PTFE preform 102 is disposed outside the core 101. There are holding headers 103 on both the upper and lower sides of the core 101. The holding header 103 holds down the position holder 104 of the cylindrical preform 102. The position holder 104 has a ring shape and also functions to seal pressure. The position holder 104 is provided with a pressure sealing portion 104a made of a heat-resistant rubber having a tongue-like cross section that enters and exits by hydraulic pressure or mechanical force. The state shown in FIG. 9 shows a state in which the tongue-like portion of the pressure sealing portion 104a is drawn. The two-dot chain line in the figure shows a state where the pressure is sealed and positioned by the tongue-shaped portion. The core 101 is installed on a support base 106, and each of the concentrically cylindrical inner heater 107, the cylindrical preform 102, and the cylindrical outer heater 108 is disposed between 2 to 5 mm. Further, a lifting rod 109 is attached to both heaters 107 and 108. Further, an apparatus for applying fluid pressure to the cylindrical preform 102 in the direction toward the central axis thereof is disposed on the outer periphery of the cylindrical preform 102. That is, with the pressurized fluid introduced from the fluid introduction valve unit 110, the inner tube of the double cylinder 111 disposed so as to surround the outer periphery of the cylindrical preform 102 is centered with respect to the outer periphery of the preform 102. A number of fluid introduction holes 112 are provided so that fluid pressure is evenly applied in the axial direction. Position holders 105 are attached above and below the double cylinder 111 in the same manner as the position holder 104 attached to the core. Similar to the pressure seal 104a of the position holder 104, the position holder 105 is provided with a pressure seal 105a made of a heat-resistant rapper having a tongue-shaped cross section that is moved in and out by hydraulic pressure or mechanical force, and the tongue is retracted. It is installed on the support base 106. Also, the heat sources of both heaters 107 and 108 are not provided in the vicinity of the tongue-shaped pressure sealing portions 104a and 105a of the position holders 104 and 105. By doing so, even if the tongue-shaped pressure sealing portions 104 a and 105 a are in contact with the PTFE preform 102, no burning occurs. Although not shown, auxiliary means such as lifting from the upper part or applying a little pressure in the cylindrical preform 102 can be taken for self-supporting of the preform 102. In some cases, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin (PFA) is attached to the outside of the preform 102 to make the pressure of the fluid even more uniform. As the pressurized fluid, for example, a gas such as nitrogen gas, a liquid having a low viscosity such as an organic heat medium, or the like is preferably used. Since the fluid temperature is selected from 50 to 300 ° C., a heating device may be necessary. The pressure is usually 10 to 100 kgf / cm ² . S. P. As with the M method, the heater is not the combination of the outer heater 108 and the inner heater 107, both of which are outside the core 1 as described above, but the inner heater is incorporated in the core 1 as well. Good. Moreover, the apparatus for cooling after melt-pressing a molding is normally incorporated in a core.

It manufactures as follows using such an apparatus. The inner and outer cylindrical heaters 107 and 108 are energized to maintain the surface temperature of the preform 102 at 375 to 450 ° C. to melt the preform. When the thickness of the preform is about 5 mm, the time required for heating is 5 to 30 minutes. After the preform 102 is melted, the inner and outer heaters 107 and 108 are pulled upward by the lifting rod 109. Next, hydraulic pressure or forward mechanical force 113 is applied to the tongue-shaped pressure sealing portions 104a and 105a of the position holders 104 and 105 from the inside and outside of the preform 102, and the position is held and pressure sealed with the preform 102 interposed therebetween. Then, the pressure fluid introduction valve unit 110 is rapidly opened, and is, for example, 10 kgf / cm ² or more, preferably 20 kgf / cm ² or more, particularly preferably 50 kgf / cm ² or more with nitrogen gas at about 100 ° C. The inside of the double cylinder 111 is rapidly filled with pressure. The required time is 1 to 20 seconds, and 60 seconds at the longest. At this time, the surface of the core is kept at 300 ° C. or lower, preferably 150 ° C. or lower. As a result, the preform 102 is wound around the core 101 to become a screw-type bellows base 114 (two-dot chain line). In the case of a screw-type bellows-like core, the core can be easily removed by cooling and rotating the core. If this core is an axisymmetric normal bellows, a normal bellows can be obtained. In this case, the core can not be removed in the same way as the screw type, so it is slightly different in terms of the method performed by turning over as described above, but up to the point where fluid pressure is used without using the outer die. Are common. Hereinafter, this method will be referred to as Equalized Pressure Molding (abbreviated as EPM method).

(Modified example of Equalized Pressure Molding)
In addition, E.I. P. What is made by the M method is not limited to the screw-type bellows, but can also be applied to ordinary bellows. In this case, the core removal is S.I. P. It is made in the same way as the M method. Moreover, although it is not a bellows, the thing of various shapes, for example, a spherical molded product, is also possible. In that case, the core is a spherical product made of baked clay or ceramics. If the core is used without removing the core, or if the molded product is an incomplete spherical product, it is not covered with a spherical shape. The core is broken and removed. Thereby, various shaped objects can be obtained.

[Method of Making Bellows of the Present Invention Using PTFE Bellows Cut or Blow Molded as a Pre-formed Product]
(Another method for manufacturing screw-type bellows, etc.)
Yet another modification is shown. Using bellows manufactured by lathe cutting, S. P. The bellows of the present invention is made by the M method. FIG. 10 is a longitudinal sectional view of an apparatus for making the bellows of the present invention in such a case. A five mountain bellows 201 manufactured by a cutting process using a lathe is installed on the lower full support base 202. The five mountain bellows 201 are formed with flange portions 201a and 201b at both ends, which are necessary for the core removal step. In addition, the core removal device support 203 is also installed on the lower full support base 202, and the core removal pressure vessel 204 is installed thereon. The core pull-out pressure vessel 204 is supported by a support member 205. In the initial stage, the five-belt bellows core 206 is pulled up to the position of the two-dot chain line in the figure by the core pull-up rod 207. The cylindrical heater 208 is also lifted by the lifting rod 209. The core withdrawing pressure vessel 204 is held at a predetermined pressure by O-rings 210 and 211 at the top and bottom, and the five mountain bellows 201 by an O-ring 212 of the lower full support base 202. In addition, a sliding plate molding outer mold for making five mountains and a sliding plate molding pushing outer mold 213 for making five mountains are also set on the lower full support base 202 together with a driving device (not shown). Moreover, the flange part expansion apparatus 214 is installed in the position corresponding to the flange parts 201a and 201b. The flange portion expanding device 214 is securely biting into the flange portions 201a and 201b by a hydraulically operated claw-shaped chuck portion 215.

In such an apparatus, the Goyama bellows 201 manufactured by cutting with a lathe is heated uniformly to about 200 ° C. by hot air or external electric heat. Thereafter, an internal pressure of about 5 to 10 kgf / cm ² is applied from the internal pressure pressurization inlet 216. At the same time, an external force 217 in the centrifugal direction is applied to the flange portion expanding device 214. The size is about 11 to 13 kgf per 1 cm of the circumferential length of the flange when the thickness of the flange is 4 mm and the width is 40 mm. As a result, the five-sided bellows 201 produced by the cutting process expands substantially uniformly and is in close contact with the inner surface of the five-sided sliding plate molding outer die and the five-sided sliding plate molding post-pressing outer die 213. (201c indicated by a two-dot chain line in the figure). The heating in this process is only for expanding the outer mold, and it is sufficient to soften the resin. However, even if it is melted from the size and shape of the molded product, it can be melted if there is no concern about flow during the next step because of the extremely high melt viscosity of PTFE. Next, the core 206 is installed on the lower full support base 202, and the cylindrical heater 208 is lowered and installed between the five mountain bellows 201 and the core 206 manufactured by cutting. Next, the cylindrical heater 208 is energized and maintained at 375 to 425 ° C. Thereby, the inside of the five mountain bellows 201 manufactured by cutting is completely melted. The time required is 5 to 30 minutes. Next, the cylindrical heater 208 is pulled up by a lifting 209, and a sliding plate molding outer mold for making a five mountain and a sliding plate molding boosting outer mold 213 for making a five mountain are advanced toward the center and manufactured by cutting. The formed five mountain bellows 201 is pressurized and melt-pressed. Thereafter, the bellows of the present invention can be obtained by carrying out in the same manner as in the example given at the beginning. Similarly, it is clear that the bellows of the present invention can be made using a bellows manufactured by blow molding as a preform. Moreover, it is applicable not only to a normal bellows but also to a screw-type bellows. In this case, the core can be removed only by rotating the core, as described above. Further, the S.I. P. Instead of using the M method, P. The same can be done with the M method. S. P. Regardless of the M method, E.E. P. In both cases, the M method is similar to ironing clothing, but more than that, it has a mirror-finished surface that eliminates fuzz. Of course, it is possible to iron one mountain at a time.

(Modification)
Yet another modification is shown. What has been described so far was that the melt-pressed shape was a bellows or a bellows part, but the shape is not a curvature as much as a bellows, but a bellows shape with a gentle wavy surface is created, Thereafter, pressure may be applied from both ends to compress the molded product to produce a bellows or a bellows part. Therefore, in the manufacturing method described above, the shape of the melt-pressed product includes not only a bellows or a bellows part, but also a gentle wave shape.

(Modification 2)
The method of the present invention is not limited to the above-mentioned molding of PTFE, but also has a high flow resistance, specifically, a resin having a fluid resistance of 500,000 P (poise) or more, more preferably 1,000,000 P (poise) or more, such as heat. Applicable to curable resin.

  The bellows of the present invention used in a semiconductor manufacturing apparatus is extremely useful in that it does not generate particles. In addition, PTFE bellows used in other nanotechnology can also be used widely and suitably.

  In addition, since the bellows of the present invention is highly transparent, it can be used for bellows through which various chemicals flow, and it is possible to know abnormal reactions such as generation of internal foreign matters and bubbles inside from the outside.

  Moreover, this invention bellows is used suitably for the system which uses an ultrapure water production line or ultrapure water.

  Further, when the cell gap of the liquid crystal display surface is, for example, 1500 nm, it is said that even the presence of about 1/10 of the particles causes a misalignment portion, so-called “dullness”. Since such particles are not generated, a liquid crystal display surface free from dullness caused by the particles can be obtained. Moreover, there is a possibility that it can be used for an organic EL display surface.

  In addition, it is said that the presence of particles in liquefied natural gas, which is fuel for fuel cells, causes the failure of the entire process or a stain on the cell catalyst. However, if the bellows of the present invention are used, no particles are generated. Provide a fuel cell with less energy consumption.

  In addition, ready-made products may be used, or specially prepared products may be used as preforms, and the degree of freedom is high. In particular, in the latter case, mixing of metal ions and the like can be avoided, and a more preferable one can be obtained.

It is the perspective view which notched a part which shows the state which inserted the cylindrical preform in the apparatus which makes the melt compression molding of a single bellows. FIG. 2 is a top partial view of FIG. 1 (a heater is not shown). It is the upper surface whole view which looked at the state after making the melt compression molding product of a single bellows from the same direction as FIG. (A) It is a thing of the first step in an explanatory view showing a process of making a flange part required in order to pull out a core from a single bellows base material (vertical section upper part partial view). (B) FIG. 4a is a more advanced view illustrating the process of making the flange portion necessary for removing the core from the single bellows base. (C) In the explanatory view showing the process of making the flange part necessary for removing the core from the single bellows base, the turned-up first stage pressing metal flange of FIG. Replacement and further turnover. (D) In the explanatory view showing the process of making the flange part necessary for removing the core from the single bellows base, FIG. 4c is further advanced to complete the turning. It is a longitudinal cross-sectional view of the single bellows original material after creating a flange up and down. It is a longitudinal cross-sectional view of a core removal apparatus. It is a longitudinal cross-sectional view after welding a single bellows into a triple bellows. It is explanatory drawing which shows the process of making what was divided | segmented at the top of the mountain | belt of a single bellows, making the annular | circular thing which opened the hole corresponded to the bellows opening length on the PTFE flat plate, and (a) is preforming. (B) is a cross-sectional view after turning it over, (c) is a cross-sectional view after welding, and (a ') is for making a screw-type bellows. It is a cross-sectional view after performing melt press molding of a preform. It is a longitudinal cross-sectional view of the metal mold | die apparatus which produces a screw type bellows. It is a longitudinal cross-sectional view of a shaping | molding apparatus when using the bellows manufactured by the cutting process by a lathe.

1 ... Ichiyama making core,
1p ... 1 mountain part of the core,
2 ... Cylindrical inner heater,
3 ... PTFE cylinder,
4 ... Cylindrical outer heater,
5a-5h ... outer mold,
5ap to 5hp ... Mountain part of outer mold,
6a-6h ... outer mold for boosting,
6ap to 6hp ... the peak part of the outer mold for boosting,
8 ... Ichiyama Bellows base,
8d ... A mountain bellows base 8 completely turned over,
29 ... Internal pressure pressurizing inlet,
30 ... Flange part expansion device,
101 ... core,
102 ... preformed product,
110: Pressure fluid introduction valve part,
201 ... Gosan Bellows,
214 ... Flange part expansion device,
216: Internal pressure pressurizing inlet.

Claims (5)

A bellows or a part constituting the bellows, characterized in that at least the inner surface is made of polytetrafluoroethylene having a mirror surface. The bellows or the part constituting the bellows according to claim 1, wherein the bellows or the bellows are free from lint and scaly slices as observed with a microscope. The component constituting the bellows or bellows according to claim 1 or 2, wherein the visible light transmittance at a thickness of 1 mm is 50% or more. The bellows according to any one of claims 1 to 3, or a part constituting the bellows, wherein the bellows is a screw type. A fluid pressure feeding device using the bellows or the bellows according to any one of claims 1 to 4.

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