JP4933599B2 - Method for producing sintered resin sheet - Google Patents

Description

  In the present invention, for example, a sintered body in which a granular resin material such as a fluororesin or an ultrahigh molecular weight polyethylene resin is pressure-sintered in a molding die is cut into a sheet material by using a blade. The present invention relates to a method for producing a resin sheet.

  For example, an air-driven double-acting diaphragm pump that places importance on safety is known as a pump for transferring (pressing) paints and chemicals (see, for example, Patent Document 1). In this type of diaphragm pump, the suction and discharge of fluid into the pump chamber is repeated by reciprocating a diaphragm arranged so as to face the pump chamber with a predetermined stroke. At this time, as the diaphragm, there is provided a structure in which a rubber material having a thin plate shape reinforced with reinforcing fibers is disposed on the back side of a fluororesin sheet having excellent chemical resistance.

  In this case, the fluororesin sheet cannot be molded by a molding method used in general synthetic resins such as injection molding and extrusion molding. Therefore, in order to manufacture a fluororesin sheet used for the diaphragm, as shown in FIG. 4, first, a pellet-like fluororesin material 1 is sintered in a pressurized state in a mold 4 to form a cylindrical shape. A method is adopted in which a molded body 2 is obtained, and a cutting blade 7 is applied to the outer peripheral surface of the molded body 2, and so to speak, as in “peeling radish” (FIG. 4 (a)). To (c)).

JP 2003-239866 A

  By the way, as shown in FIG. 4 (d), the fluororesin sheet material 3 obtained by the manufacturing method as described above has a mark of a cutting blade 7 called a tool mark T on the surface. It is known that some things remain as parallel streaks.

  On the other hand, in the diaphragm pump as described above, an air cylinder (or the second diaphragm) is incorporated on the same axis as the diaphragm, and the shaft driving the diaphragm is mechanically added to the driving force by the driving air. It is conceivable to give a general assist force. In this type of diaphragm pump, the fluid discharge pressure can be obtained at a pressure ratio (pump ratio) of 2: 1 or 3: 1 when the input pressure of the driving high-pressure air is 1.

  However, in such a diaphragm pump with a pump ratio of 2: 1 or 3: 1, the pressure ratio on the inner and outer surfaces of the diaphragm is 2: 1 or 3: 1, so that a large load repeatedly acts on the diaphragm. There are circumstances to do. When such a large load is repeatedly applied to the diaphragm made of the fluororesin sheet material 3, the tool mark T on the surface grows into a crack and breaks in a relatively short time. In particular, when the fluid is an organic solvent or the like, the organic solvent penetrates into the rubber layer on the back side through the cracks, leading to a problem that the diaphragm is broken early (for example, in several hours).

  The present invention has been made in view of the above circumstances, and its purpose is to cut a molded body obtained by sintering into a sheet material by using a blade, and when a load acts repeatedly It is in providing the manufacturing method of the sheet | seat made from a sintered resin which can improve durability.

  In a sintered resin sheet in which a molded body obtained by sintering is thinly cut into a sheet material using a blade, a trace of a blade called a tool mark on the surface of the sheet material, that is, parallel streaks It is considered that the unevenness causes the occurrence of cracks when the load is repeatedly applied. Therefore, if the tool mark generated on the surface of the sheet material in the cutting process can be easily erased by subsequent processing, the tool mark is prevented from growing into a crack during actual use, and the above object is achieved. be able to.

The method for producing a sintered resin sheet according to the present invention includes a sintering step in which a granular resin material is pressure-sintered in a molding die to obtain a molded body, and the molded body is sliced using a blade to obtain a sheet material. saw including a between the cutting step of a flattening step of flattening the surface of the sheet material, the planarization step, wherein particles to the surface of the sheet material where performed by blasting spraying at high speed (Invention of claim 1) According to this, by performing the flattening process on the sheet material obtained in the cutting process, the surface of the sheet material is flattened as a whole, and thereby the tool mark generated on the surface of the sheet material Can be erased, or even if a tool mark remains, the degree of unevenness can be made moderate.

At this time , the flattening step was performed by a blasting process in which particles were sprayed at high speed on the surface of the sheet material . According to this, the entire surface of the sheet material can be flattened by blasting so that the convex portion of the tool marks generated on the surface of the sheet material is crushed. In this case, the blasting process can be easily performed with a relatively inexpensive apparatus, and the process complexity and cost increase can be suppressed.

Moreover, at this time, when performing the joining process which joins another member with respect to one surface of the sheet material obtained by the said cutting process, it is also possible to perform the joining process after a planarization process. However, it is preferable to perform the flattening step on the other surface of the sheet material after the joining step (invention of claim 2 ). When the joining process is performed while pressing and heating the sheet material, it can be expected that the other surface of the sheet material is flattened during the joining process, and the order is reversed. Compared with the case where it did, it becomes possible to perform the subsequent planarization process efficiently in a short time. In addition, before the flattening step is performed, it can be expected that the bonding property with another member becomes better due to the unevenness of the tool mark.

  According to the method for producing a sintered resin sheet of the present invention, a molded body obtained by sintering is sliced into a sheet material using a blade, and the surface of the sheet material is flattened after the cutting step. By executing the flattening process, the tool mark formed on the surface of the sheet material can be erased, and the durability is improved by suppressing the occurrence of cracks and damage when the load is repeatedly applied. There is an excellent effect of being able to.

The 1st Example of this invention is a figure which shows the manufacturing process of a diaphragm. Diaphragm longitudinal section Longitudinal sectional view schematically showing the internal structure of the diaphragm pump The figure which shows the manufacturing process until resin material is made into sheet material in order The figure which shows a mode that blast processing is executed

(1) First Example Hereinafter, a first example in which the present invention is applied to manufacture of a diaphragm mainly composed of a fluororesin sheet will be described with reference to FIGS. In addition, although mentioned later in detail, the diaphragms 11 and 11 'manufactured in a present Example are comprised mainly by the fluororesin sheet | seat 12 as a sintered resin sheet. The diaphragms 11 and 11 ′ are used for a diaphragm pump 21 that constitutes a part of the coating system, for example.

  Although not shown in detail, the painting system is an air-driven double-acting type in which a coating device such as a spray gun, a paint supply source, and paint (or cleaning liquid such as thinner) from the paint supply source are pumped toward the coating device. The diaphragm pump 21 (see FIG. 3), an air supply mechanism for supplying high-pressure air for driving to the diaphragm pump 21, and the like are provided. FIG. 3 schematically shows a configuration of a diaphragm pump 21 with an assist mechanism that can obtain a fluid discharge pressure at a pressure ratio (pump ratio) of 3: 1 with respect to an input pressure of high-pressure air for driving. Yes. The configuration of the diaphragm pump 21 will be briefly described.

  That is, the housing (body) 22 of the diaphragm pump 21 has a cylindrical (drum) outer shape whose axis is directed in the left-right direction, and the first and second pump chambers 23, 23 are provided at both left and right end portions thereof. 'Is provided symmetrically. Note that members (parts) equivalent to the first pump chamber 23 in the second pump chamber 23 ′ are denoted by the same reference numerals with “′” added thereto.

  The first pump chamber 23 is provided in the left wall portion of the housing 22 and has a flange portion 24 having a circular concave portion 24a at the center of the inner surface, and a disc shape provided on the right side so as to close the circular concave portion 24a. The diaphragm 11 is formed. On the other hand, the second pump chamber 23 ′ is provided on the right wall portion of the housing 22 and has a flange portion 24 ′ having a circular concave portion 24 a ′ at the center of the inner surface, and the circular concave portion 24 a ′ on the left side thereof. And a disk-shaped diaphragm 11 ′ provided on the surface. At this time, the center portion of the diaphragm 11 is connected to the left end portion of the shaft 25 extending in the left-right direction in the housing 22, and the right end portion of the shaft 25 is connected to the center portion of the diaphragm 11 ′. Details of the diaphragms 11 and 11 'will be described later.

  A manifold 26 is attached to the left side surface portion of the housing 22. The manifold 26 has a liquid passage 27 extending in the vertical direction, and a suction valve 28 including a check valve including a valve seat, a valve ball, a spring, and the like is incorporated in a lower end portion of the liquid passage 27. A discharge valve 29 comprising a similar check valve is incorporated in the upper end portion of the liquid passage 27. A midway portion of the liquid passage 27 and the circular concave portion 24a (first pump chamber 23) of the flange portion 24 communicate with each other through an inlet / outlet hole 27a.

  Furthermore, the lower end of the manifold 26 (liquid passage 27) is connected to the left end of a suction pipe 30 extending in the left-right direction at the lower portion of the housing 22, and the upper end of the manifold 26 (liquid passage 27) is connected to the housing. A left end portion of a discharge pipe 31 extending in the left-right direction is connected to the upper portion of 22. A suction port 30 a is provided downward at the left end portion of the suction pipe 30, and a discharge port 31 a is provided upward at the left end portion of the discharge pipe 31. Although not shown, the suction port 30a is connected to a paint supply source via a pipeline, and the discharge port 31a is connected to a coating apparatus via a pipeline.

  As a result, when the diaphragm 11 is displaced rightward in the drawing by the shaft 25, the volume of the first pump chamber 23 is increased to a negative pressure, the suction valve 28 is opened (the discharge valve 29 is closed), and the suction port 30a. A suction process is performed in which liquid (paint or cleaning liquid) is sucked into the first pump chamber 23 from the (suction pipe 30). On the other hand, when the diaphragm 11 is displaced to the left in the drawing by the shaft 25, the liquid in the first pump chamber 23 is pushed out, the discharge valve 29 is opened (the suction valve 28 is closed), and the discharge port 31a (discharge) A discharge step of discharging liquid (paint or cleaning liquid) toward the pipe 31) is performed.

  On the other hand, also in the second pump chamber 23 ′, a manifold 26 ′ is attached to the right side surface portion of the housing 22 in the figure. Similarly, the manifold 26 ′ includes a liquid passage 27 ′, a suction valve 28 ′, a discharge valve 29 ′, etc., and a midway portion of the liquid passage 27 ′ and a circular concave portion 24 a ′ of the flange portion 24 ′. The (second pump chamber 23 ') is communicated with an inlet / outlet hole 27a'. The lower end portion of the liquid passage 27 ′ is connected to the right end portion of the suction pipe 30, and the upper end portion of the liquid passage 27 ′ is connected to the right end portion of the discharge pipe 31.

  The housing 22 is provided with an air drive mechanism 32 that is positioned on the right side and drives the shaft 25 to reciprocate in the left-right direction with a predetermined stroke. Is provided. In the cylinder 33, an air piston 34 connected to the middle portion of the shaft 25 is provided.

  Thus, when the diaphragm 11, the diaphragm 11 'and the shaft 25 are integrally reciprocated with a predetermined stroke in the left-right direction in the drawing, when one pump chamber 23, 23' is in the suction process, the other pump chamber The steps 23 'and 23 are the discharge process, which are alternately repeated, so that the liquid is continuously pumped. At this time, by adding the assist force by the air piston 34, the fluid discharge pressure can be obtained at a pressure ratio of 3: 1 with respect to the input pressure of the driving high-pressure air.

  Now, the diaphragm 11.11 ′ will be described. Since these diaphragms 11.11 'are only provided symmetrically and are the same parts, the diaphragm 11 will be described below as a representative. As shown in FIG. 2, the diaphragm 11 has a substantially disk shape as a whole, and has a fluororesin sheet 12 made of, for example, PTFE on the front side, and another member on the back side of the fluororesin sheet 12. The NBR rubber layer 14 is integrally joined.

  Further, a fiber reinforcing material 13 made of a thin cloth made of nylon, for example, is provided in the intermediate layer portion in the rubber layer 14. At this time, the fluororesin sheet 12 as a sintered resin sheet is composed of a circular thin plate-shaped fluororesin sheet material 3 manufactured by a manufacturing method described later. The sheet material 3 has a thickness dimension of, for example, about 1 mm to 1.5 mm.

  Further, a mounting disk 15 is embedded in the central portion on the back side of the rubber layer 14, and a set screw 16 with a hexagonal hole is fixed to the central portion of the back surface of the disk 15. Projects to the back side. The diaphragm 11 is assembled in the housing 22 of the diaphragm pump 21 in such a form that the outer peripheral side portion is sandwiched from both the front and back surfaces, and is connected to the shaft 25 by the set screw 16 at this time.

  Next, a method for manufacturing the diaphragm 11 (fluororesin sheet 12) in the present embodiment will be described with reference to FIGS. FIG. 1 schematically shows a manufacturing process of a fluororesin sheet 12 (sheet material 3) and a diaphragm 11 in the present embodiment. That is, in manufacturing the diaphragm 11, a sintering process P1, a cutting process P2, a joining process P3, and a blasting process P4 as a flattening process are sequentially performed.

  Among them, the sintering process P1 and the cutting process P2 are processes for manufacturing a sheet material 3 made of a fluororesin (for example, PTFE), and are performed as shown in FIG. That is, first, in the sintering step P1, as shown in FIG. 4A, the granular (pellet-shaped) fluororesin material 1 is pressure-sintered in the mold 4 to obtain the molded body 2. Done. At this time, the molding die 4 includes a lower die (fixed die) 5 having a cylindrical cavity 5a, and an upper die (contacting / separating from above the lower die 5 and pressurizing the fluororesin material 1 in the cavity 5a ( A movable type) 6 and a heater (not shown) for heating them are provided.

  By performing this sintering process P1, as shown in FIG. 4B, a cylindrical molded body 2 made of a fluororesin material is obtained. In the next cutting step P2, the cylindrical molded body 2 is cut into thin pieces using a cutting blade 7 which is a cutter. Specifically, as shown in FIG. 4C, the cutting blade 7 is attached to the outer peripheral surface of the molded body 2 so that the extending direction of the cutting edge is parallel to the axial direction (an angle close to parallel). In other words, a method of slicing, such as “peeling radishes”, is used.

  By this cutting process P2, a sheet-like sheet material 3 made of fluororesin is obtained. At this time, as shown in FIG. 4 (d), the surface (both sides) of the sheet material 3 has a large or small size, but the marks (unevenness) of the cutting blade 7, which is referred to as the tool mark T, are formed on the cutting blade 7. It is known to remain as parallel streaks extending in the relative direction of travel.

  Since this sheet material 3 is continuous and long, although not shown, the sheet material 3 is punched into a circular shape using a press device after the cutting step P2, and By the press, it is in a state in which a peculiarity is given so as to be close to the final shape of the fluororesin sheet 12 (slightly three-dimensional shape having irregularities in the surface direction).

  In the next joining process P3, the rubber layer 14 as another member is joined to the back side of the punched sheet material 3 (fluororesin sheet 12) to obtain the diaphragm 11. Although not shown, in this joining step P3, for example, a molding die having a cavity corresponding to the outer shape of the diaphragm 11 (excluding the set screw 16) is used. In obtaining the diaphragm 11 (joining the rubber layer 14), the punched sheet material 3 (fluororesin sheet 12), the fiber reinforcing material 13, and the mounting disk 15 are arranged in the mold. Then, the rubber material (NBR) is vulcanized and molded. As a result, insert molding is performed, and the rubber layer 14 in which the fiber reinforcing material 13 is embedded is integrally joined to the back surface, which is one surface of the fluororesin sheet 12. The diaphragm 11 in which the mounting disk 15 is embedded is obtained.

  Finally, a blasting process P4 is performed as a flattening process for flattening the surface of the fluororesin sheet 12 (the other surface of the sheet material 3). In this blast processing step P4, for example, a blast processing device (blast gun) 8 as shown in FIG. 5 is used. As is well known, this blasting device 8 is configured to convey particles 9 for polishing such as ceramic or metal while being mixed with compressed air and to inject them from a nozzle 8a at the tip at a high speed. In the embodiment, the particles 9 are sprayed at a high speed on the surface of the fluororesin sheet 12 of the diaphragm 11.

  By this blasting process P4, the entire surface of the fluororesin sheet 12 is flattened so that the convex portion of the tool mark T generated on the surface of the fluororesin sheet 12 of the diaphragm 11 is crushed. The tool mark on the surface of the fluororesin sheet 12 can be erased. Alternatively, even if the tool mark remains, the degree of unevenness can be made moderate.

  The diaphragm 11 (fluororesin sheet 12) manufactured as described above is used for the diaphragm pump 21 in which the above-described pump ratio is 3: 1. The ratio of the pressure acting on the front and back sides of the diaphragm 11 is as follows. However, since the ratio is 3: 1, there is a situation in which a large load repeatedly acts on the diaphragm 11.

  Here, as described in the conventional example, if the tool mark T remains on the surface of the fluororesin sheet 12 constituting the diaphragm 11, the load is repeatedly applied to the diaphragm 11. There is a possibility that the tool mark T on the surface of the sheet 12 grows into a crack and is damaged in a relatively short time. In particular, when the fluid to be pumped is an organic solvent such as thinner, the organic solvent penetrates into the rubber layer 14 on the back side through the crack, and the diaphragm 11 is torn early (for example, in several hours). It will cause problems.

  However, in the diaphragm 11 (fluororesin sheet 12) of the present embodiment, the tool mark T that causes the generation of cracks generated on the surface of the sheet material 3 in the cutting process P2 can be easily performed through the blasting process P4. As a result, the tool mark T can be prevented from growing into a crack and the durability can be greatly improved. Incidentally, according to the experiments by the present inventors, in the conventional diaphragm that does not execute the blasting process P4, the tearing occurred in several hours when the organic solvent was pumped. 11, it has been confirmed that a lifetime of several hundred hours can be obtained.

  As described above, according to this example, the molded body 2 obtained by pressure sintering of the fluororesin material 1 was sliced using the cutting blade 7 to obtain the sheet material 3 (fluororesin sheet 12). In the diaphragm manufacturing method, even if the generation of the tool mark T on the surface of the sheet material 3 (fluororesin sheet 12) is unavoidable in the cutting process P2, the blasting process P4 performs the fluororesin. The surface of the sheet 12 can be flattened as a whole. Therefore, the tool mark T on the surface of the fluororesin sheet 12 can be erased, and it is possible to improve the durability by preventing problems such as cracks and breakage when a load is repeatedly applied to the diaphragm 11. Excellent effect.

  In particular, in the present embodiment, since the blasting process using the blasting device 8 is adopted as the planarization process, the planarization process can be easily and reliably performed with a relatively inexpensive apparatus. Complexity and cost increase can be suppressed. Further, particularly in the present embodiment, the blasting process (flattening process) P4 is performed after the bonding process P3. Therefore, during the bonding process P3, constant planarization of the other surface of the sheet material 3 is performed. Compared with the case where the order is reversed, it is possible to perform the subsequent flattening step P4 more efficiently in a shorter time. Further, before the flattening step P4 is performed, it can be expected that the bonding property with another member (rubber layer 14) becomes better due to the unevenness of the tool mark T.

  In each of the above-described embodiments, as the cutting step P2, the case where the cylindrical molded body 2 is thinly cut (skived) like a radish katsura is exemplified. However, as the cutting step, a cylindrical shape is used. The molded body 2 may be cut (sliced) in a ring shape, and the tool mark can be similarly erased by a subsequent flattening step. Moreover, in the said 1st Example, although the case where the sheet | seat material 3 is arrange | positioned in a shaping | molding die and vulcanization molding of rubber | gum was performed as an example as a joining process, for example, the sheet | seat material 3 and another member (different materials) May be pasted together with an adhesive. Of course, the sheet material 3 can be used alone.

  Further, the resin material to be pressure-sintered in the mold is not limited to fluororesin (PTFE), but may be other fluororesin other than PTFE, or ultra high molecular weight polyethylene resin. good. Additives such as fillers may be contained in the resin material. Of course, the heating temperature of the hot press treatment may be appropriately set depending on the type of the resin material. In addition, the sintered resin sheet (sheet material) manufactured by the manufacturing method according to the present invention is not limited to the diaphragm 11 for the diaphragm pump 21 and can be used for various applications. It can be implemented with appropriate modifications within the range.

  In the drawings, 1 is a resin material, 2 is a molded body, 3 is a sheet material, 4 is a mold, 7 is a cutting blade (blade), 8 is a blasting device, 9 is particles, 11 is a diaphragm, and 12 is a fluororesin sheet ( (Sintered resin sheet), 14 is a rubber layer (another member), and T is a tool mark.

Claims (2)

A sintering step of obtaining a molded body by pressure-sintering a granular resin material in a mold; and
A cutting step in which the molded body is cut into a sheet material using a blade, and
Look including the flattening step of flattening the surface of the sheet material,
The method for producing a sintered resin sheet, wherein the flattening step is performed by a blasting process in which particles are sprayed at a high speed on the surface of the sheet material . While performing the joining process which joins another member to one side of the sheet material obtained by the cutting process,
The method for producing a sintered resin sheet according to claim 1 , wherein the flattening step is performed on the other surface of the sheet material after the joining step .

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