JPH0821529A - Manufacture of bellows - Google Patents

Abstract

PURPOSE:To facilitate manufacturing of bellows an also improve sealing performance by simplifying the structure of a metal mold. CONSTITUTION:A cylindrical hollow molded body 2A is made of elastic resin. The hollow molded body 2A is inserted into a mold 10, and low stress relaxation resin is poured into both ends of the hollow molded body 2A through a communication passage 17 to form a bellows intermediate body, and the resin coming around the communication passage 17 of the bellows intermediate body is removed, and notches are made in the hollow molded body 2A to form a bellows section 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a bellows used for a valve device for controlling a flow of fluid.

[0002]

2. Description of the Related Art Conventionally, there is a bellows as shown in FIG. That is, the bellows 100 is a bellows with a valve used in a valve device for controlling the flow of fluid, and is provided on the outer peripheral surface of the cylindrical bellows portion 101 and one unbent end portion of the bellows portion 101. A fixing portion 102 that is held in a case (not shown) of the valve device and has a flange shape that faces outward in the radial direction, and a radial inward direction provided on the inner peripheral surface of the other end of the bellows portion 101 that does not bend. The valve unit 103 is configured to come into contact with and separate from a valve seat (not shown) of a valve device having a flange shape.

The bellows portion 101 is made of a flexible resin (eg, tetrafluoroethylene resin, PTFE, etc.), and the fixing portion 102 and the valve portion 103 are injection-moldable rubber-like elastic materials. And an elastic plastic material.

Further, a concave portion 104 is formed on the outer peripheral surface of one end portion of the bellows portion 101, which is not bent, to form a retaining portion for preventing the fixing portion 102 from coming off, and the other portion is bent. A concave portion 105 is formed on the inner peripheral surface of the end portion that does not come off, and serves as an engagement portion for preventing the valve portion 103 from coming off. Then, the convex portion 106 formed on the inner peripheral surface of the fixed portion 102 is fitted into the concave portion 104, and the convex portion 107 formed on the outer peripheral surface of the valve portion 103 is fitted into the concave portion 105,
Each is fitted and fixed to the bellows portion 101.

[0005]

However, in the case of the above-mentioned prior art, since the fixing portion 102 and the valve portion 103 constituting the bellows 100 are divided into both ends of the bellows portion 101, the bellows 100 is molded. At the time of molding, two injection ports (not shown) for injecting the molding material into the cavity of the mold are required on the fixed part 102 side and the valve part 103 side, and the mold structure becomes complicated. , Productivity is poor.

Further, since the fixing portion 102 and the valve portion 103 are provided only on the outer peripheral side or the inner peripheral side of the bellows portion 101, the concave portions 104 and 105, which are engagement portions for preventing coming off due to temperature changes.
When a gap in the radial direction is generated at the boundary portion of, the leakage from the inside of the bellows 100 to the outside occurs particularly in the valve portion 103.

The present invention has been made in order to solve the above-mentioned problems of the prior art. The purpose of the present invention is to achieve simplification of the structure of the mold, thereby facilitating manufacture and sealing. It is an object of the present invention to provide a method for manufacturing a bellows which can also improve the property.

[0008]

In order to achieve the above object, according to the present invention, a tubular hollow molded body is formed of a flexible resin and the hollow molded body is inserted into a mold. Then, a resin with less stress relaxation is injected into both ends of the hollow molded body through a communication path to form a bellows intermediate body, and the resin wrapping around the communication path of the bellows intermediate body is removed, It is characterized in that a notch is formed in the molded body to mold the bellows portion.

It is preferable to provide resin engagement portions for preventing the resin from coming off with less stress relaxation at both ends of the hollow molded body.

Further, the connecting passage is provided on the inner peripheral side of the hollow molded body, or on the outer peripheral side of the hollow molded body so that a resin with less stress relaxation is allowed to flow so as not to enter the inner peripheral side of the hollow molded body. May be.

[0011]

According to the method of manufacturing the bellows having the above-mentioned structure, the hollow molded body forming the bellows portion is inserted into the mold, and the resin with less stress relaxation is injected into both ends thereof through the connecting passages. Since the fixed part and the valve part are molded, only one injection port for injecting the resin into the mold is required. Therefore, the structure of the mold can be simplified.

Further, since the resin is injected into both ends of the hollow molded body at the same time by one injection port, the bellows intermediate body can be molded in one shot, which facilitates manufacturing.

Further, by providing a resin engaging portion for preventing the fixed portion and the valve portion from coming off at both ends of the hollow molded body forming the bellows portion, the resin is engaged with the resin engaging portion at the time of molding, After molding, the fixed parts and the valve parts at both ends are securely engaged.

By making the connecting path on the inner peripheral side of the hollow molded body, the resin material injected at both ends wraps around from the inner peripheral side to the outer peripheral side of the hollow molded body including the resin engaging portion. Therefore, even if there is radial deformation due to temperature change, one of the resins on the inner and outer peripheries is engaged with the hollow molded body, and after molding, leakage from the inside of the bellows to the outside is prevented. It does not occur, and as a result, the sealing property is improved.

Further, the connecting passage is provided on the outer peripheral side of the hollow molded body so that the resin injected from both the outer peripheral side of the hollow molded body into the inner peripheral side of the hollow molded body is prevented from flowing into the inner peripheral side. Since it is not necessary to push the hollow molded body from the inner peripheral side toward the outer peripheral side by the pressure of the resin,
It is possible to prevent deformation of the hollow molded body inserted in the mold.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiments. FIG. 1 shows a mold in a method of manufacturing a bellows according to an embodiment of the present invention, and FIG. 2 shows a bellows which is a molded product.

First, the bellows which is the molded product shown in FIG. 2 will be described.

This bellows 1 is a bellows with a valve used in a valve device for controlling the flow of fluid, which is the same as the conventional bellows.
A tubular bellows portion 2, a fixing portion 3 having a flange shape radially outward and held in a case (not shown) of a valve device provided at one end of the bellows portion 2 which does not bend, and a bellows The valve portion 4 is provided at the other non-bending end of the portion 2 and comes in contact with and separates from a valve seat (not shown) of a valve device having a radially inward flange shape.

The bellows portion 2 is made of a resin (for example, tetrafluoroethylene resin, PTFE, etc.) having a bending resistance under high temperature (about 100 ° C. or more) and is formed in a tubular shape. A fixing portion convex portion 5 having a resin engaging portion for preventing the fixing portion 3 from protruding axially outward is formed in the middle portion in the radial direction, and the other end surface is formed on the inner peripheral surface of the bellows portion 2. A valve portion convex portion 6 having a resin engaging portion for preventing the valve portion 4 from projecting axially outward is formed.

On the outer peripheral surface of the convex portion 5 for the fixed portion, a retaining groove 7 (which may be a convex portion) for preventing the stationary portion 3 from coming off is formed. Further, on the outer peripheral surface of the convex portion 6 for the valve portion, a retaining recess 8 (which may be a convex portion) for retaining the valve portion 4 is formed.

The fixed portion 3 and the valve portion 4 are made of injection-moldable resin. This resin has little stress relaxation under high temperature (about 100 ° C. or higher). The fixing portion 3 is provided over the entire circumference including the retaining portion concave portion 7 in the fixing portion convex portion 5 at one end of the bellows portion 2, and has a radially outward flange shape. Further, the valve portion 4 is provided over the entire circumference of the valve portion convex portion 6 at the other end of the bellows portion 2 including the retaining recess 8 and has a radially inward flange shape. A rod (not shown) is mounted in a fluid-tight manner. On the peripheral edge of the outer end surface of the valve portion 4, there is formed an annular valve portion 9 which projects outward in the axial direction and which comes into contact with and separates from the valve seat.

Next, a method of manufacturing the bellows 1 will be described with reference to the mold shown in FIG. This mold 10
The hollow molded body 2A forming the bellows portion 2 is inserted into the annular cavity 11, the resin is injected into the cavity 11, and the fixing portion 3 and the valve portion 4 are attached to both ends of the hollow molded body 2A forming the bellows portion 2. It is injection molded. Correspondingly, the cavity 11 has a cavity valve portion (hereinafter abbreviated as CAV valve portion) 12 and a cavity bellows portion (hereinafter abbreviated as CAV bellows portion) 1 in order from the left side in the drawing.
3 and a cavity fixing portion (hereinafter, abbreviated as CAV fixing portion) 14, and each of them has an annular shape.

CAV valve section 12, CAV bellows section 13, CA
The outer diameter of the V fixing portion 14 is a small diameter portion, a middle diameter portion, and a large diameter portion in that order, and the inner diameters of the V fixing portion 14 are the CAV bellows portion 13 and the CAV fixing portion 14.
And CAV valve portion 12 have a smaller diameter.

A cylindrical hollow molded body 2A made of a flexible resin is inserted into the cavity 11 thus constructed. This cylindrical hollow molded body 2A
Will later form the bellows portion 2, and one of its end faces
A fixed portion convex portion 5 having a retaining recess 7 is provided on the outer peripheral surface, and a valve convex portion 6 having a retaining recess 8 on the outer peripheral surface is provided on the other end surface.

The hollow molded body 2A has a predetermined radial gap between the inner peripheral surface of the hollow molded body 2A and the inner peripheral surface of the CAV bellows 13, and the outer peripheral surface of the hollow molded body 2A and the CAV bellows. CAV fixing so that the outer peripheral surface of 13 is closely contacted, and the end surface of the hollow molded body 2A on the valve convex portion 6 side is in close contact with the end surface of the step portion of the CAV valve portion 12 and the CAV bellows portion 13. The end surface of the convex portion 5 for the fixed portion is pressed and inserted by the protrusions 15 provided on the circumference in a radial intermediate portion of the end surface of the portion 14 in a circumferentially distributed manner.

Then, the hollow molded body 2A having been inserted
A gate 16 (indicated by a white arrow in the figure) as an injection port is formed in the mold 10 so as to face the inner diameter side of the fixing portion convex portion 5 and to open into the cavity 11 for injecting the resin into the cavity 11. There is.

Next, molding will be described.

First, the hollow molded body 2A is placed in the cavity 11.
In the state of being inserted as described above, injection-moldable resin with less stress relaxation is injected from the gate 16. The injected resin flows from the inner diameter side of the fixing portion convex portion 5 to the outer diameter side thereof through the gap of the protrusion portion 15. On the other hand, since the inner peripheral surface of the hollow molded body 2A and the inner peripheral surface of the CAV bellows portion 13 have a predetermined radial gap, the resin injected from the gate 16 through this gap is CAV.
The resin flows to the valve portion 12 side, and then the resin flows around the end surface of the valve portion convex portion 6 from the inner diameter side to the outer diameter side. In this way,
The fixed portion 3 and the valve portion 4 are injection-molded through a gap on the inner peripheral side of the hollow molded body 2A, and a bellows intermediate body (not shown) is molded. Therefore, the above-mentioned gap is formed between the CAV fixing portion 14 and the CA.
It serves as a communication path 17 for fluid resin with the V valve portion 12.

As described above, the bellows intermediate body is molded, and then the mold 10 is released, and the resin that has flowed into the communication path 17 of the released bellows intermediate body is hollow-molded as shown in FIG. The inner peripheral surface of the body 2A is cut and removed. At this time, the inner circumferential surface of the valve projection 6 is also slightly cut. Then, after cutting, the resin is left on the inner peripheral surface of the convex portion 5 for the fixed portion 5 and the convex portion 6 for the valve portion having the concave portions 7 and 8 for retaining (the portion within the circle in the figure). After that, the bellows portion 2 is completed by forming cut portions in the inner and outer peripheral surfaces of the hollow molded body 2A alternately to form the bent portions 18, and thus the bellows portion 2 is formed.

According to the above method of manufacturing the bellows, the mold 1
Since the communication passage 17 is provided between the CAV fixing portion 14 and the CAV valve portion 12 in the cavity 11 of 0, the fixing portion 3,
Since only one gate 16 for injecting the resin into the cavity 11 is required when the valve portion 4 is molded, the structure of the mold 10 is simplified as compared with the conventional two molds.

Further, since the resin is injected into both ends of the hollow molded body 2A at the same time by one gate 16, the bellows intermediate body can be molded by one shot, which facilitates the manufacture.

Further, at both ends of the bellows portion 2 made of a flexible resin, there are provided retaining portions 7 and 8 formed on the outer peripheral surface of the fixing portion 3 and the valve portion 4 which are made of a resin having less stress relaxation. Since the protrusions for the fixed portion 5 and the protrusions for the valve portion 6 are circulated around and engaged with each other through the interposition, even if there is a deformation in the radial direction due to a temperature change, a gap is formed on either the inner or outer peripheral side. Since they are engaged without using each other, it is possible to prevent leakage at the boundary portions between the convex portion 5 for the fixed portion and the fixed portion 3, and the convex portion 6 for the valve portion and the valve portion 4. Since the valve portion 4 does not leak from the inside of the bellows 1 to the outside, the sealability can be improved.

Since the fixing portion 3 and the valve portion 4 are formed of a resin having less stress relaxation, the durability (compression creep resistance) can be improved when the bellows 1 is used.

Since only the bellows portion 2 is made of a resin having bending resistance and the fixing portion 3 and the valve portion 4 are made of a resin that can be injection-molded, it is possible to produce an inexpensive bellows.

Then, the hollow molded body 2A and the fixing portion 3 and the valve portion 4 are mechanically fixed to the injection-molded resin in the retaining recesses 7 and 8. In this embodiment, the retaining recesses 7 and 8 are provided on the outer periphery. Since it is provided on the surface, there is an effect that it can be processed in one shot with the outer peripheral profile and the forming tool. This is because the molding shrinkage of the resin is used to generate shimeiro (that is, stress equivalent to shrink fit) in the hollow molded body 2A, and the sealing property of the boundary portion is secured.

Next, a specific example of the mold in the manufacturing method according to the embodiment of the present invention will be described with reference to FIG.

This mold 20 is for injection molding and is roughly provided with an upper mold 21 and a lower mold 22, and a cavity 23 is formed between the mating surfaces of the upper mold 21 and the lower mold 22. .

The upper die 21 includes the first, second and third upper dies 24,
25 and 26. The first upper mold 24 is annular and has a tapered hole 27 whose inner peripheral surface is a tapered surface whose diameter decreases downward in the axial direction.

The second upper mold 25 has a first upper mold recess 28 into which the first upper mold 24 is inserted at one end in the axial direction, and a third upper mold 26 at the other end. A first upper mold 24 having a third upper mold recess 29 and communicating these recesses 28, 29.
The communication hole 30 has a diameter substantially the same as the diameter of the tapered hole 27 on the large diameter side.

In the first upper mold recess 28 of the second upper mold 25, the first upper mold 24 has a communication hole 30 on the large diameter side of the tapered hole 27.
Side so that the guide screw A31
The upper mold 24 and the second upper mold 25 are integrally screwed and fixed. Since the depth of the first upper mold recess 28 is larger than the thickness of the first upper mold 24, the first upper mold recess 28 is formed.
The outer peripheral portion of is projected below the end surface of the first upper mold 24.

Further, the third upper mold 26 has a core having a radially outward flange portion 32 at one end and a convex portion 33 projecting on the central axis at the other end surface. And the third
Until the upper die 26 engages in the third upper die concave portion 29 of the second upper die 25 of the first and second upper die 24, 25 integrated as described above with the convex portion 33 facing downward. The upper die 21 is configured by being inserted in contact with the inner peripheral surfaces of the communication hole 30 and the tapered hole 27, and being integrally screwed and fixed to the second upper die 25 by the guide screw B31A at the flange portion 32. To be done.

On the other hand, the lower mold 22 includes the first and second lower molds 34 and 35 in which the upper mold 21 and the cavity 23 are formed, and the first and second lower molds 34 and 35.
The third lower mold 37 has first and second lower mold recesses 36 into which the second lower molds 34 and 35 are inserted.

The first lower mold 34 has a radially outward flange portion 38 at one end thereof and an annular convex portion 39 projecting along the outer peripheral surface thereof at the other end surface thereof. A pin hole 40A for inserting the pin 40 is formed therethrough. The tip of the pin 40 projects from the end surface of the first lower mold 34, and the tip of the pin 40 contacts the end surface of the convex portion 33 of the third upper mold 26 when the upper mold 21 and the lower mold 22 are aligned. It is like this.

The second lower mold 35 has a first lower mold recess 41 into which the first lower mold 34 is inserted, and the first lower mold recess 41 is formed.
Is formed through almost the center of the
There are large, medium, and small cavity holes 42, and the outer diameter of the second lower mold 35 itself is substantially the same as the inner diameter of the first upper mold recess 28 of the second upper mold 25.

Also, the first lower mold recess 41 of the second lower mold 35.
At the open end of the, there is a step portion 43 that engages with the flange portion 38 of the first lower mold 34. Then, in the first lower mold recess 41 of the second lower mold 35, the end surface of the annular convex portion 39 of the first lower mold 34 contacts the bottom surface of the first lower mold recess 41, and the flange portion 38 is stepped. Engages the portion 43, and the first lower mold 34 and the second lower mold 3
The first lower mold 34 is inserted together with the pin 40 so that the surface 5 and the surface 5 are flush with each other. At this time, the inner diameter of the annular convex portion 39 of the first lower mold 34 is smaller than the diameter of the small diameter portion of the cavity hole 42 of the second lower mold 35.

Then, the first and second parts mounted in this way
The lower molds 34 and 35 are inserted into the first and second lower mold recesses 36 of the third lower mold 37 with the first lower mold 34 facing downward,
The second lower mold 35 and the third lower mold 37 are screwed and fixed by the guide screw C44 at the bottom of the second lower mold recess 36, whereby the first, second, and third lower molds 34, 35 are formed. , 37 are integrated to form the lower mold 22. The depth of the first and second lower mold recesses 36 is smaller than the thickness of the second lower mold 35, and the outer diameter of the second lower mold 35 is substantially equal to the inner diameter of the first upper mold recess 28. The same, and since the outer peripheral portion of the first upper mold recess 28 projects, the tip end of the second lower mold 35 is inserted into the first upper mold recess 28, and the end face of the first upper mold 24 Second
The upper die 21 and the lower die 22 are aligned with the end surface of the lower die 35.
And are matched.

At this time, the convex portion 33 of the third upper mold 26 becomes the second
The lower die 35 is inserted so as to face the cavity hole 42, and the end face of the convex portion 33 is brought into contact with the end face of the pin 40. Thereby, the annular cavity 23 is formed.

The cavity 23 has an inner peripheral surface of the annular convex portion 39 of the first lower die 34, an end surface of the first lower die 34 in the annular convex portion 39, an outer peripheral surface of the pin 40, and a convex portion of the third upper die 26. The CAV valve portion 45 formed by the end surface of the portion 33, the end surface of the annular convex portion 39 of the first lower die 34, and the cavity hole 4 of the second lower die 35.
CAV bellows portion 46 formed on the inner peripheral surface of the small diameter portion 2 and the outer peripheral surface of the convex portion 33 of the third upper die 25, and the inside and the large diameter portion of the cavity hole 42 of the second lower die 35. A peripheral surface and an end surface between them, an end surface of the first upper mold 24, an outer peripheral surface of the third upper mold 26, an end surface of the convex portion 33 and a CAV fixing portion 47 formed by the outer peripheral surface of the convex portion 33. Has been done.

A cylindrical hollow molded body 2A 'made of a resin having bending resistance is provided in the cavity 23.
Is inserted. This tubular hollow molded body 2A ′ is
A bellows portion 2'is formed later, and one end surface of the bellows portion 2'is provided with a retaining recess 7'as a resin engaging portion on the inner and outer peripheral surfaces.
The convex portion 5'for a fixed portion having a convex portion 5'for a valve portion and the convex portion 6'for a valve portion having a retaining concave portion 8'as a resin engaging portion are provided on the other end surface.

The hollow molded body 2A 'has a predetermined radial gap between the inner peripheral surface of the hollow molded body 2A' and the outer peripheral surface of the convex portion 33 of the CAV bellows portion 46, that is, the connecting passage 17 '. And the outer peripheral surface of the hollow molded body 2A 'and the inner peripheral surface of the small diameter portion of the cavity 42 of the CAV bellows portion 46 are in close contact, and the end surface of the hollow molded body 2A' on the side of the convex portion 6'for the valve portion is the CAV bellows. A plurality of the CAV fixing portions 47 are equally distributed on the circumference in the radial middle portion of the end surface of the CAV fixing portion 47 with the convex portion 33 of the third upper mold 26 so as to be in close contact with the end surface of the annular convex portion 39 of the first lower mold 34 of the portion 46. The end surface of the convex portion 5'for the fixing portion is pressed and inserted by the projection 15 'provided on the.

On the other hand, in the third upper mold 26, the cavity 2 for injecting the resin into the cavity 23 facing the inner diameter side of the fixing portion convex portion 5'of the hollow molded body 2A 'that is inserted.
A gate 16 ′ as an inlet opening to 3 and a spool 48 are formed.

Further, the first lower mold 34 and the third lower mold 37 have ejector pin holes 49 which are formed coaxially therethrough and which open the end face of the hollow molded body 2A 'inserted into the cavity 23. The ejector pin 50 is reciprocally inserted into the ejector pin hole 49, and the ejector plate 51 is provided at the lower end of the ejector pin 50.

Next, the molding in the mold 20 having the above construction will be described. First, with the hollow molded body 2A 'inserted in the cavity 23, a resin that can be injected from the gate 16' and has less stress relaxation is injected. The injected resin is applied to the protrusion 1 from the inner diameter side of the fixing portion convex portion 5 '.
It flows into the outer diameter side through a gap of 5 '. In addition, the resin injected from the gate 16 'is the hollow molded body 2
It flows to the CAV valve part 45 side through the communication path 17 'on the inner peripheral side of A'. The resin flows around the valve convex portion 6 ′ from the inner diameter side to the outer diameter side. In this way, the fixed portion 3 ′ and the valve portion 4 ′ are injection-molded via the communication passage 17 ′ on the inner peripheral side of the hollow molded body 2A ′, and the bellows intermediate body (not shown) is molded.

As described above, the bellows intermediate body is molded, then the upper mold 21 is released from the lower mold 22, and after the mold release,
The ejector plate 50 is pushed and the bellows intermediate body is taken out by the ejector pin 49. Then, the resin that has entered the communication path 17 'of the bellows intermediate body is cut and removed together with the inner peripheral surface of the intermediate molded body 2A'. Retaining recess 7 ', even after cutting
The resin is left on the inner peripheral surfaces of the convex portion 5 ′ for the fixed portion and the convex portion 6 ′ for the valve portion having 8. Bellows 1'is completed by making cuts alternately on the inner and outer peripheral surfaces of hollow molded body 2A 'to form bent portions 18' to form bellows portion 2 '(FIG. 4).
reference).

In this bellows 1 ', since the fixed portion convex portion 5'has retaining recesses 7'on the inner and outer circumferences,
The fixed portion 3'is even more difficult to pull out.

Next, a method of manufacturing the bellows of another embodiment of the above-mentioned embodiment will be described with reference to FIG. In this manufacturing method, the communication path 17A is molded by a mold 10A having a cavity 11A on the outer peripheral side of the hollow molded body 2A.

First, the cavity 11A formed by the mold 10A will be described.

The cavity 11A has an annular shape similar to the above embodiment, and the CAV valve portions 12A and CAV are arranged in order from the left side in the drawing.
It is composed of a bellows portion 13A and a CAV fixing portion 14A.
The CAV valve portion 12A, the CAV bellows portion 13A, and the CAV fixing portion 14A have outer diameters of a small diameter, a medium diameter, and a large diameter portion in order, and inner diameters of the CAV bellows portion 13A and the CAV fixing portion 1.
4A has almost the same diameter, and the CAV valve portion 12A has a smaller diameter than that.

The hollow molded body 2A is placed in the cavity 11A.
Is inserted. That is, the outer peripheral surface side of the hollow molded body 2A is used as the connecting path 17A, and the inner peripheral surface of the hollow molded body 2A and C
The end surface of the CAV fixing portion 14A is closely contacted with the inner diameter side peripheral surface of the AV bellows portion 13A, and the resin wraps around the inner and outer peripheries of the fixing portion convex portion 5 and the valve portion convex portion 6 of the hollow molded body 2A. A plurality of protrusions 15 equidistantly arranged on the circumference in the middle part in the radial direction.
A and the CAV valve portion 12A end portions of the convex portion 5 for the fixed portion 5 and the convex portion 6 for the valve portion are pressed and inserted by the protrusions 15B provided on the circumference in the radial middle portion in a radial direction. It

Then, the hollow molded body 2A having been inserted
The gate 16A (indicated by a white arrow in the figure) as an inlet opening into the cavity 11A for injecting the resin toward the communication path 17A provided on the outer peripheral side of the CAV fixing portion 14 is provided.
It is formed so as to open on the outer peripheral surface of A.

Then, a bellows intermediate body (not shown) is molded by passing a flow resin (flowing the resin from the fixed portion 3 to the valve portion 4) through the communication passage 17A on the outer peripheral side of the hollow molded body 2A. The resin and the outer peripheral surface of the hollow molded body 2A that have flown into the communication path 17A are cut and removed, and then the bellows are molded through the steps as in the above embodiment.

However, in the case of this manufacturing method, when the resin is injected from the gate 16A to mold the bellows intermediate body, the step 52 of the hollow molding 2A on the outer diameter side of the fixing portion convex portion 5 is fixed. The hollow molded body 2A is pushed to the outer diameter side of the cavity 11A and deformed by the injection pressure of the resin on the end surface of the convex portion 5 for the portion and the inner diameter side of the convex portion 5 for the fixed portion, whereby the communication path 17A is formed. In some cases, the hollow molded body 2A may be blocked and cannot be molded, and the hollow molded body 2A is made of a material suitable for the bellows portion 2, that is, a low elastic modulus material of resin (PTFE or the like) having bending resistance (for example,
000 kg / cm ² ) is used, there is a problem that permanent deformation easily occurs depending on the state of the insert (see FIG. 6), and moldability is poor.

Therefore, in order to solve the above problems, a method of manufacturing a bellows according to another embodiment of the present invention will be described.

First, the mold 10C shown in FIG. 7 will be described. The mold 10C is composed of a mold I90 and a mold II91. A cavity 11C is formed by the mold I90 and the mold II91, and the hollow molded body 2C forming the bellows portion 2C 'is inserted into the annular cavity 11C. The resin is injected into the cavity 11C, and the fixed portion 3C and the valve portion 4C are injection-molded at both ends of the hollow molded body 2C forming the bellows portion 2C '. Corresponding to this, the cavity 11C has CAV valve portions 12C, CA in order from the left side in the drawing.
It is composed of a V bellows portion 13C and a CAV fixing portion 14C, both of which are annular.

The CAV valve portion 12C, the CAV bellows portion 13C,
The outer diameter of the CAV fixing portion 14C is a small, medium, and large diameter portion in order, and the inner diameter of the CAV bellows portion 13C and the CAV fixing portion 14C are substantially the same and are on the same plane.
The valve portion 12C has a smaller diameter than that.

A cylindrical hollow molded body 2C made of a flexible resin is inserted into the cavity 11C thus constructed. This tubular hollow molded body 2
C later forms a bellows portion 2C ', and a hollow molded body 2 having a retaining recess 7C on the outer peripheral surface at one end face thereof.
The inner periphery of the hollow molded body 2C is similar to the protrusion 5C for fixed part, which is provided with the protrusion 5C for fixed part protruding along the inner peripheral surface of C and has the retaining recess 8C on the outer peripheral surface on the other end face. A convex portion 6C for the valve portion that projects along the surface is provided.

The hollow molded body 2C has a predetermined radial gap between the inner peripheral surface of the hollow molded body 2C and the outer peripheral surface of the CAV bellows portion 13C, that is, on the outer peripheral side of the hollow molded body 2C. The inner peripheral surface of the hollow molded body 2C and the inner peripheral surface of the CAV bellows portion 13C are brought into close contact with each other via the communication path 17C, and the end surface of the convex portion 5C for the fixing portion of the hollow molded body 2C is CAV.
The mold I9 is attached so as to be in close contact with the end surface of the mold II91 of the fixed portion 14C.
No. 0 CAV valve portion 12C and CAV bellows portion 13C end portion of the stepped portion 6C side end portion of the hollow molded body 2C by the projections 15C provided on the circumference in the radial middle portion of the end surface of the step portion. Is pressed and inserted.

At this time, the CAV bellows portion 1 serving as a support portion is provided to the mold II 91 so that the valve convex portion 6C is not buckled or deformed.
A support convex portion 53 protruding along the inner peripheral surface of 3C is provided, and the end surface of the support convex portion 53 and the end surface of the valve portion convex portion 6C are flush with each other.

Then, a gate as an injection port opened in the CAV fixing portion 14C of the cavity 11C for injecting the resin toward the communication path 17C provided on the outer peripheral side of the hollow molded body 2C inserted as described above. 16C is type I
The 90 CAV fixing portion 14C is formed so as to be open on the outer peripheral surface.

Then, a bellows intermediate (not shown) is molded by passing a flow resin (flowing the resin from the fixed portion 3C to the valve portion 4C) through the connecting passage 17C on the outer peripheral side of the hollow molded body 2C. The resin and the outer peripheral surface of the hollow molded body 2C that have entered the communication path 17C are cut and removed, and then the bellows 1C is molded through the steps as in the first embodiment (see FIG. 8).

According to the manufacturing method of this embodiment, the connecting passage 17C is provided on the outer peripheral side of the hollow molded body 2C, and the resin injected from the outer peripheral side of the hollow molded body 2C into both ends thereof does not enter the inner peripheral side. 5C for fixing part of hollow molded body 2C
Since the end face of the CAV fixing portion 14C is in close contact with the end face of the mold II 91, the pressure in the axial direction of the fluid resin is less likely to be applied, and when the resin is injected, the convex portion 5C for the fixing portion from the end face side is hollow molded body. It will not enter the inner circumference side of 2C. As a result, the hollow molded body 2C is not expanded from the inner peripheral side toward the outer peripheral side by the pressure of the fluidized resin, so that the deformation of the hollow molded body 2C inserted into the mold 10C can be prevented. The moldability is improved.

In order to prevent the axial pressure of the fluid resin from being applied, the following dimensional relationships are preferable.

Assuming that the cross-sectional area of the connecting passage 17C is C, the cross-sectional area of the fixed portion convex portion 5C is A, and the cross-sectional area of the hollow molded body 2C is B, the cross-sectional area C of the connecting passage 17C is B-A. It is preferable that ≦ C. Moreover, it is also suitable that A ≧ 0.7B. This is because the pressure of the fluid resin does not largely act on the stepped portion with the fixed portion convex portion 5C, that is, the portion B-A.

In this way, when the pressure of the fluid resin acts on the hollow molded body 2C, the pressure acts on the portion B-A, but by setting B-A≤C, the fluid resin can be smoothly flowed. , The pushing force to the left in the figure can be weakened. Further, the protrusion 15C of the mold I90 can prevent the hollow molded body 2C from moving to the left in the figure, so that the hollow molded body 2C can be reliably held in the cavity 11C.

Next, a specific example of the mold in the manufacturing method according to this embodiment will be described with reference to FIG.

The mold 60 is for injection molding, and roughly includes an upper mold 61 and a lower mold 62, and a cavity 63 is formed between the mating surfaces of the upper mold 61 and the lower mold 62. .

The upper die 61 includes a first upper die 64 and a second upper die 65.
It is composed of

The first upper mold 64 has a substantially rectangular cross section, has a flange portion 66 facing outward in the radial direction at one end, and has a cavity recess 67 for forming the cavity 63 at the other end surface. .

The second upper mold 65 is an annular member having a first upper mold recess 68 into which the first upper mold 64 is inserted. The cavity inner hole 69 has a small diameter and a large diameter in order from the top. have. Further, at the opening end of the first upper mold recess 68,
The first upper die 64 has a step portion 70 that engages with the flange portion 66 of the first upper die 64, and the outer peripheral end surface of the cavity concave portion 67 of the first upper die 64 has a first step inside the first upper die concave portion 68. By contacting the bottom surface of the upper mold recess 68 and engaging the flange portion 66 with the step portion 70, the first upper mold 64 and the second upper mold 65 are integrated to form the upper mold 61.

On the other hand, the lower mold 62 is composed of first, second, third and fourth lower molds 71, 72, 73 and 74.
The first lower mold 71 includes the second, third and fourth lower molds 72, 73, 7
It has a substantially U-shaped cross section having a lower mold recess 75 into which 4 is inserted. Then, the annular second and third lower molds 72 and 73 are sequentially stacked in the lower mold recess 75, and the fourth lower mold is placed in the holes 76 and 77 of the second and third lower molds 72 and 73. By inserting 74, the second, third, and fourth lower molds 7
2, 73, 74 are arranged.

A step portion 78 having a diameter larger than the hole diameter is provided at the opening end of the recess 75 of the hole 76 of the second lower mold 72 on the bottom surface side. Further, the hole 77 of the third lower mold 73 has a tapered shape whose diameter expands downward in the drawing, and the hole diameter at the lower end thereof is slightly smaller than the diameter of the hole 76 of the second lower mold 72. Has become. As a result, when the third lower mold 73 is stacked on the second lower mold 72, a stepped portion is formed at the hole 76 and the hole 77.

Further, the fourth lower mold 74 has a convex portion 79 which faces the cavity 69 of the second upper mold 65, and the second, third
It forms a core that is inserted into the holes 76 and 77 of the lower molds 72 and 73, and has a flange portion 80 that faces outward in the radial direction at the lower end portion. Then, the convex portion 79 and the flange portion 80
The outer diameter is gradually increased from the convex portion 79, and is formed by a small diameter portion 74A, a taper portion 74B that increases in diameter toward the flange portion 80, and a large diameter portion 74C. Large diameter part 7
The diameter of 4C is substantially the same as the diameter of the hole 76 of the second lower die 72, and the tapered portion 74B is substantially the same as the tapered shape of the hole 77 of the third lower die 73. An annular concave portion 81 is formed on the upper end surface of the convex portion 79, and the height of the outer peripheral portion thereof is lower than that of the central portion.

Then, the fourth lower die 74 is placed in the hole 76 of the second lower die 72, and the flange portion 80 of the fourth lower die 74 is the step portion 7 of the second lower die 72.
8 until it is engaged, and in that state is inserted into the lower mold recess 75 of the first lower mold 71. After insertion, guide screw D82
, The first lower mold 71 and the second lower mold 72 are screwed and fixed, and the first, second, and fourth lower molds 71, 72, 74 are integrated,
By inserting the tapered hole 77 of the third lower mold 73 into the tapered portion 74B of the fourth lower mold 74, and inserting the hole 77 into the lower mold recess 75, and stacking the hole on the second lower mold 72, the lower mold 62 is formed. Is configured. At this time, the small diameter portion 7 of the fourth lower mold 74
4A projects from the end surface of the third lower mold 73, and the end surface of the third lower mold 73 is lower than the outer peripheral end surface of the lower mold recess 75 of the first lower mold 71.

The end surface of the second lower die 65 of the upper die 63 is brought into contact with the end surface of the third lower die 73 of the lower die 62, and the upper die 61 and the lower die 62 are aligned.

At this time, the convex portion 79 and the small diameter portion 74A of the fourth lower mold 74 are inserted so as to face the cavity hole 69 of the second upper mold 65, and the end face of the central portion of the convex portion 79 having the annular concave portion 81 is inserted. Is brought into contact with the bottom surface of the cavity recess 67 of the first upper mold 64. Thereby, the annular cavity 63 is formed.

The cavity 63 includes a CAV valve portion 83 formed by the cavity recess 67 of the first upper die 64 and the annular recess 81 of the protrusion 79 of the fourth upper die 64, and the first upper die 64.
Outer peripheral end surface of the cavity concave portion 67, the inner peripheral surface of the small diameter portion of the cavity hole 69 of the second upper mold 65, and the fourth lower mold 74.
CAV bellows portion 84 formed on the outer peripheral surface of the convex portion 79 of
And the inner peripheral surfaces of the small and large diameter portions of the cavity 69 of the second upper die 65 and the end surfaces between them, the end surface of the third lower die 73, and the peripheral surface of the small diameter portion 74A of the fourth lower die 74. And a CAV fixing portion 85.

Then, a cylindrical hollow molded body 2B made of a resin having bending resistance is inserted into the cavity 63. The tubular hollow molded body 2B later forms a bellows portion 2B ', and one end surface thereof has a retaining recess 7B on the outer peripheral surface as a resin engaging portion, and the inner peripheral surface of the hollow molded body 2B. Projection 5 for fixing part protruding along the surface
B has a retaining recess 8B on the outer peripheral surface serving as a resin engaging portion on the other end surface, and for the valve portion protruding along the inner peripheral surface of the hollow molded body 2B, similarly to the fixing portion convex portion 5B. Convex part 6B
Is provided.

The outer peripheral surface of the hollow molded body 2B and the inner peripheral surface of the small diameter portion of the cavity hole 69 of the second upper die 65 of the CAV bellows portion 84 of the cavity 63 have a predetermined radial gap.
That is, the hollow molded body 2B has a communication path 17B on the outer peripheral side, and the inner peripheral surface of the hollow molded body 2B and the fourth of the CAV bellows portion 84 are connected.
The outer peripheral surface of the convex portion 79 of the lower mold 74 is closely contacted, and the end surface of the convex portion 5B for the fixing portion of the hollow molded body 2B has the CAV bellows portion 84.
Of the CAV valve portion 83 of the first upper mold 64 of the CAV valve portion 83 in the radial direction midway of the end face of the outer peripheral portion of the cavity concave portion 67 of the CAV valve portion 83 so as to be in close contact with the end surface of the fourth lower mold 74. The hollow molded body 2B is formed by a plurality of protrusions 15D provided on the upper surface of the hollow molded body 2D.
The end surface of the valve portion convex portion 6B is pressed and inserted.

On the other hand, between the second upper die 65 and the third lower die 73, the convex portion 5 for the fixed portion of the hollow molded body 2B inserted is provided.
A spool 48B is formed through the gate 16B as an injection port opening to the cavity 63 for injecting the resin into the cavity 63 facing the outer diameter side of B and the slit 86 of the first lower mold 71.

The first, second and third lower molds 71, 72,
73 has a large, medium, and small diameter ejector pin hole 49B formed coaxially therethrough, and the stepped ejector pin 50B is provided in the ejector pin hole 49B.
It is reciprocally inserted in the lower dies 71 and 72 and comes into contact with the lower end surface of the third lower die 73 at the step end surface of the ejector pin 50B. An ejector plate 51B is provided at the lower end of the ejector pin 50B.

Next, the molding by the mold 60 having the above construction will be described.

First, the hollow molded body 2B is placed in the cavity 63.
In a state in which is inserted, a resin with a small stress relaxation capable of injection molding is injected from the gate 16B. The injected resin is applied to the hollow molded body 2 from the outer diameter side of the fixing portion convex portion 5B.
It flows to the CAV valve portion 83 side via the connecting passage 17B on the outer peripheral side of B, and then flows to the outer diameter side of the valve portion convex portion 6B through a gap corresponding to the protrusion portion 15D, so that the valve portion convex portion 6B is formed. The resin rotates and flows from the outer diameter side to the annular recess 81. In this way, the fixed portion 3B and the valve portion 4B are injection-molded via the communication passage 17B on the outer peripheral side of the hollow molded body 2B, and a bellows intermediate body (not shown) is molded.

As described above, the bellows intermediate body is molded, then the upper mold 61 is released from the lower mold 62, and after the mold release,
The bellows intermediate body is taken out by pushing the ejector plate 51B and pushing the third lower mold 73 at the step end face of the ejector pin 50B. Then, the resin that has entered the communication path 17B of the bellows intermediate body is cut and removed together with the outer peripheral surface of the intermediate molded body 2B. After cutting, the resin is left on the outer peripheral surfaces of the fixed portion convex portion 5B and the valve portion convex portion 6B. Then, cuts are alternately formed on the inner and outer peripheral surfaces of the hollow molded body 2B to form the bent portion 18
The bellows 1B is completed by forming B to form the bellows portion 2B '(see FIG. 10).

[0094]

EFFECTS OF THE INVENTION The present invention has the above-mentioned structure and action, and a hollow molded body forming a bellows portion is inserted into a mold, and a resin with less stress relaxation is injected into both ends of the hollow molded body through a connecting path. Since the fixed part and the valve part are molded, only one injection port for injecting the resin into the mold is required. Therefore, the structure of the mold can be simplified.

Further, since the resin is injected into both ends of the hollow molded body at the same time by one injection port, the bellows intermediate body can be molded in one shot, which facilitates the manufacture.

Further, since the resin engaging portions for preventing the fixed portion and the valve portion from coming off are provided at both ends of the hollow molded body forming the bellows portion, the resin is engaged with the resin engaging portion during molding, rear,
The fixed portion and the valve portion at both ends are securely engaged.

Since the communication path is on the inner peripheral side of the hollow molded body, the resin injected at both ends will flow from the inner peripheral side of the hollow molded body to the outer peripheral side including the resin engaging portion. Become. As a result, even if there is a radial deformation due to temperature change, one of the resins on the inner and outer peripheries will engage with the hollow molded body, so that leakage from the inside of the bellows to the outside will occur after molding. Is eliminated, and as a result, the sealing property is improved.

Further, since the above-mentioned connecting path is provided on the outer peripheral side of the hollow molded body so that the resin injected from the outer peripheral side of the hollow molded body to both ends thereof does not enter the inner peripheral side, the fluid resin is injected at the time of resin injection. The pressure does not push the hollow molded body from the inner peripheral side toward the outer peripheral side. As a result, it is possible to prevent deformation of the hollow molded body inserted into the mold, and improve moldability.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a mold used in a method for manufacturing a bellows according to an embodiment of the present invention.

2 (a) is a half sectional view of a bellows molded by the mold of FIG. 1, FIG. 2 (b) is a sectional view of the valve portion of FIG. 2 (a), and FIG. 8A is a cross-sectional view of the fixing portion in FIG.

FIG. 3 is a cross-sectional view of a mold of a specific example used in a method for manufacturing a bellows according to an embodiment of the present invention.

FIG. 4 is a half sectional view of a bellows molded by the mold of FIG.

FIG. 5 is a schematic configuration diagram of a mold according to another aspect of the first embodiment.

6 is a schematic configuration diagram showing a state in which a hollow molded body is deformed by a fluid resin in the mold of FIG.

FIG. 7 is a schematic configuration diagram of a mold used in a method for manufacturing a bellows according to another embodiment of the present invention.

8 is a half sectional view of a bellows molded by the mold of FIG.

FIG. 9 is a cross-sectional view of a mold of a specific example used in a method of manufacturing a bellows according to another embodiment of the present invention.

FIG. 10 is a half sectional view of a bellows molded by the mold of FIG.

FIG. 11 is a half sectional view of a conventional bellows.

[Explanation of symbols]

1,1 ', 1B, 1C Bellows 2,2', 2B ', 2C' Bellows part 2A, 2A ', 2B Hollow molded body 3,3', 3B, 3C Fixed part 4,4 ', 4B, 4C Valve part 5,5 ', 5B, 5C Fixed part convex part 6,6', 6B, 6C Valve part convex part 7,7 ', 7B, 7C, 8,8', 8B, 8C Retaining concave part 9 Valve part 10 , 10A, 10C, 20 Mold 11, 11A, 11C, 23, 63 Cavity 12, 12A, 12C, 45, 83 Cavity valve part (CAV valve part) 13, 13A, 13C, 46, 84 Cavity bellows part (CAV bellows) 14) 14, 14A, 14C, 47, 85 Cavity fixing part (CAV fixing part) 15, 15 ', 15A, 15B, 15C, 15D Protrusion 16, 16', 16A, 16B, 16C Gate 17, 17 ', 17A, 17B, 17C connecting path 18, 1 ', 18B Bent portion 21,61 Upper mold 22,62 Lower mold 24,63 First upper mold 25,65 Second upper mold 26 Third upper mold 27 Tapered hole 28,68 First upper mold recess 29 Third upper mold Mold recess 30 Communication hole 31 Guide screw A 31A Guide screw B 32 Flange part 33 Convex part 34,71 First lower mold 35,72 Second lower mold 36 First and second lower mold recess 37,73 Third lower Mold 38 Flange portion 39 Annular convex portion 40 Pin 40A Pin hole 41 First lower mold concave portion 42,69 Cavity hole 43 Step portion 44 Guide screw C 48,48B Spool 49,49B Ejector pin hole 50,50B Ejector pin 51,51B Ejector plate 52 Step portion 53 Support convex portion 66,80 Flange portion 67 Cavity concave portion 70,78 Step portion 74 Fourth lower mold 74A Small diameter portion 74B Taper 74C large-diameter portion 75 lower die recess 76, 77 hole 79 protrusion 81 annular recess 82 guide screw D 86 slit

Claims (4)

[Claims] 1. A tubular hollow molded body is formed from a flexible resin, the hollow molded body is inserted into a mold, and a resin with less stress relaxation is inserted at both ends of the hollow molded body through a connecting path. Of the bellows, characterized in that the bellows intermediate body is molded by injection to remove the resin wrapping around the communication path of the bellows intermediate body, and the bellows part is molded by making a cut in the hollow molded body. Production method. 2. The method of manufacturing a bellows according to claim 1, wherein resin engagement portions for preventing the resin with less stress relaxation are provided at both ends of the hollow molded body. 3. The method of manufacturing a bellows, wherein the communication path is on the inner peripheral side of the hollow molded body. 4. The connecting passage is on the outer peripheral side of the hollow molded body, and flows the resin with less stress relaxation so as not to enter the inner peripheral side of the hollow molded body.
The method for manufacturing the bellows according to 1.