JPH11170266A - Molding mold for rubber product and molding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a molding mold and which enables the improvement of the deflashing workability and production quality of a rubber product and a molding method and especially to produce an extremely small O-ring and an O-ring of fine rubber diameter easily. SOLUTION: In a molding mold 1 equipped with an upper mold 2, a middle mold 3, and a lower mold 4 (the first, second, and third mold members), a cavity CV of the division surface between the middle mold 3 and the lower mold 4, a gate part 11, and a sprue part 12 are provided. The strength at break of the gate part 11 of a molded rubber-elastic material is set up to be smaller than that of the sprue part 12, the sprue part 12 is separated from the middle mold 3 so that the sprue part 12 is separated from a product part in the gate part 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding die for molding a rubber product and a method for molding a rubber product using the molding die. Particularly, the present invention relates to a method for easily forming an extremely small O-ring or an O-ring having a small wire diameter. It relates to technology that can be manufactured.

[0002]

2. Description of the Related Art Various methods have been conventionally proposed as a method for molding a product made of a rubber-like elastic material.

FIG. 11 is a diagram schematically showing a cross-sectional configuration of a molding die 100 and a molding method for explaining an example of a molding method. This molding method is generally employed in a molding method called compression molding. It is one of the things to be done.

FIG. 11 (a) shows a state in which the upper mold 101 and the lower mold 102 are opened, and a cavity CV for forming a plurality of O-rings 200 (capable of multi-cavity) is provided in each of them. It is formed in a mold.

[0005] In the compression molding, a rubber material RS as a material measured without excess or shortage is placed on the mold opening surface of the mold 100 which has been opened, and a predetermined amount is set so as to be in the state of FIG. The mold is closed at the pressurizing pressure and pressurizing speed of.

In closing the mold, it is necessary to flow the rubber cloth RS so as to fill the inside of the cavity CV to every corner, and the molding die 100 is heated.

In such compression molding, thin burrs B1 are generated around the O-ring 200 along the parting line PL, which is the opening surface of the upper mold 101 and the lower mold 102. When performing the removal, the respective O-rings 200 are connected by burrs B1, and the O-ring 200 as a product is released together with the burrs B1 at the end of molding.

[0008] In such a release method, it is difficult to release the product when the product is placed independently in a molding die because the product has a minute shape, or the shape is complicated and the release resistance is large. It is adopted when it becomes.

Further, as shown in FIG. 11C, which is an enlarged view of a portion D101 in FIG.
An annular ring B2 having a circular or trapezoidal cross section around 0
(Formed on both the outer peripheral side and the inner peripheral side)
3, when the O-ring 200 and the burr B1 are manually separated from each other, a part of the burr B1
It is prevented from remaining around the ring 200.

[0010] The O-ring 200 immediately after molding has a burr B
Sheet molded article 21 having a sheet shape integrated with 1
When the number of multi-cavities increases, a finishing method of setting the sheet molded product 210 in a punching jig and punching out is also employed.

FIG. 12 (a) shows the O
It is explanatory drawing which made the cross section of the principal part structure explaining the separation finish operation | work of the ring.

The punching jig 300 is fitted in a punching plate 302 having a large number of punching holes 301 formed at the same pitch as the O-ring 200, an inner burr punch punch 303, an O-ring punch 304, and a punching hole 301. An inner diameter die 305 serving as a die of the inner diameter deburring punch 303 is provided as a main configuration.

The inner diameter deburring punch 303 and the O-ring punch 304 are stroked in the direction of arrow A101, and the burr B5 and the O-ring 2 at the inner diameter of the O-ring 200 are respectively provided.
Remove 00.

The punching plate 302 moves by a predetermined pitch in the direction of arrow A102 for each stroke of each punch, and
The ring 200 faces each punch. In addition, the inner diameter die 3
Numeral 05 is configured so as to move down in the direction of arrow A103 during the movement of the punching plate 302 so as not to hinder the movement of the punching plate 302.

Therefore, each time each punch makes one stroke as in a so-called transfer molding machine, the punched plate 302 moves a predetermined pitch from right to left (in the direction of arrow A102) in FIG. 200 is removed to separate the product and burrs.

In addition, as a simpler method, it is also possible to adopt a method in which a dedicated punching die and a punch are arranged for each of the burr on the inner diameter portion and the burr on the outer diameter side, and a large number of finishes are performed in separate processes. is there.

[0017]

However, when dedicated jigs are manufactured for O-rings of various sizes, it is possible to improve the productivity. It is considered that the cost is high and, depending on the production lot, it may be a factor that increases the product cost.

[0018] Further, in order to manufacture such a punching jig especially for an O-ring having a small size (for example, an outer diameter of about 1.3 mm and an inner diameter of about 0.5 mm), extremely precise and difficult processing is required. The cost is high, and the management of handling and maintenance during use is also difficult.

In addition, the operation of accurately placing the small-sized O-ring on the punching die needs to be performed with sufficient care, which lowers the workability.

Regarding the problem of the jig, for example, FIG.
As shown in (b), when assembling the punch jig 300, concentric alignment (core) for fitting the inner diameter die 305 and the inner diameter deburring punch 303 through the annular gap 306 having a uniform width. However, when the inner diameter of the O-ring is about 0.5 mm, the diameter of the inner diameter deburring punch 303 is as large as the tip of the needle, and it is difficult to adjust the centering.

When the eccentricity 307 as shown in FIG. 12 (c) exists, the O-ring is grinded or cut (P101 portion where the width of the annular gap 306 is small), and the burr remains (P102 where the width of the annular gap 306 is large). Part) may occur, resulting in a quality defect. In FIG. 12C, P1
The tip of the inner diameter deburring punch 303 on the 01 side is in a worn state, and such abrasion also causes a problem due to the O-ring biting.

Further, even if the processing accuracy of the component parts is increased and high-precision assembly is performed, it may be difficult to perform good finishing with a punch jig depending on the product shape of the O-ring.

FIG. 13 is a view for explaining a finishing defect due to the product shape of the O-ring. In FIG. 13A, O
When the wire diameter of the ring 220 is larger than the inner diameter, it is difficult to insert the inner diameter burr B20 by the inner diameter die 320 and the inner diameter punch 321 and it becomes impossible to finish the inner diameter burr B20.

FIG. 13B shows that when the wire diameter of the O-ring 230 is smaller than the inner diameter, the O-ring 230 gets caught in the gap between the outer die 330 and the outer punch 331, and 230 is damaged or outer diameter punch 33
This causes a problem in the extraction process, such as the fact that 1 cannot be removed.

FIG. 13C shows FIGS. 13A and 13B.
FIG. 4 is a diagram showing an O-ring 240 in which the problem described above does not occur.

The present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide a mold and a molding tool capable of improving the deburring workability of rubber products and the quality of rubber product production. It is an object of the present invention to provide a method, in particular, to make it possible to easily manufacture an extremely small O-ring or an O-ring having a small wire diameter.

[0027]

According to the present invention, there is provided a rubber product molding die according to the present invention, wherein the first, second and third dies are openable and superposed in order. A member, a cavity formed on a division surface between the second mold member and the third mold member for molding a product part of a rubber product, and a gate portion provided along the division surface of the cavity A second mold member having an opening on a surface of the second mold member facing the first mold member, and a spool provided on the second mold member connected to the gate. Second
By fluidizing the rubber-like elastic material disposed between the mold members and closing the mold of the first mold member, the rubber fluidized through the spool portion and the gate portion inside the closed cavity. It is characterized in that the shape elastic material can be injected.

According to this, since the fluidized rubber-like elastic material is injected into the cavity closed in advance,
The generation of burrs on the divided surface other than the gate portion of the cavity can be suppressed.

The breaking strength of the gate portion of the molded rubber-like elastic material is determined by the breaking strength of the spool portion required when the rubber-like elastic material molded in the spool portion is released from the second mold member. It is also preferred that it be smaller.

According to this, by separating the spool portion from the second mold member, it is possible to separate the spool portion and the product portion at the gate portion without leaving the spool portion on the second mold member. .

It is also preferable that the gate is connected to the inner peripheral side of a cavity for molding an annular rubber product.

According to this structure, since the gate portion is located on the inner peripheral side of the annular rubber product, even if thin burrs are generated on the divided surface other than the gate portion of the cavity, it is located on the outer peripheral side of the annular rubber product. In addition, the deburring work becomes easy.
Further, the configuration of the spool portion is simplified, and the workability of the mold can be improved.

The spool portion includes a constricted portion having a smaller cross section than the opening portion, and a nozzle portion directed from the constricted portion to the gate portion. It is also preferable to provide a concave portion that allows deformation of the nozzle portion when passing through the constricted portion during mold release.

According to this configuration, the injection of the rubber-like elastic material into the cavity is improved by the nozzle portion, and
Deformation when the concave portion passes through the constricted portion at the time of releasing the nozzle portion is allowed to suppress breakage at the time of releasing the nozzle portion, and it is possible to improve molding quality, yield, and releasability.

A pressurizing chamber having an opening of the spool portion on a dividing surface between the first mold member and the second mold member for holding and pressurizing a rubber-like elastic material; It is also preferable to provide an overflow gate and a retaining portion for allowing the rubber-like elastic material overflowing from the chamber to escape.

According to this configuration, the rubber-like elastic material can overflow at the division surface between the first mold member and the second mold member during molding, and the product of the rubber product can be formed without excessive pressure. The rubber-like elastic material is prevented from entering the dividing surface between the second mold member and the third mold member where the portion is formed, and the occurrence of thin burrs in the product portion is suppressed.

In the above-described molding method using a rubber product mold, after the rubber product is molded, the first mold member is opened, and the spool portion is closed in a state where the cavity is closed. By separating from the second mold member, the spool portion and the product portion are separated from each other at the gate portion, and then the second mold member and the third mold member are opened to open the cavity and the product portion of the rubber product is opened. Is collected.

[0038]

(Embodiment 1) A molding die 1 according to a first embodiment of the present invention will be described below with reference to FIGS. 1, 2 and 3. FIG.

FIG. 1 is a view showing a cross-sectional structure of a state in which a molding tool 1 is closed to form a rubber product by closing the mold, FIG. 2 is an enlarged view of a portion D1 in FIG. 1, and FIG. FIG. 4 is an enlarged view of a portion D2 of FIG.

The molding die 1 has an extremely small wire diameter.
In addition, it is possible to mold an O-ring R1 (product part) as a rubber product having a circumference larger than the wire diameter (for example, the wire diameter is 0.5 mm and the inner circumference of the O-ring is about 20 mm). Things.

However, the shape of the product molded by the molding die 1 is not limited to the O-ring, but can be applied to any other shape.

First, the structure of the mold 1 will be described. The molding die 1 has a general three-layer structure having an upper die 2 as a first die member, a middle die 3 as a second die member, and a lower die 4 as a third die member. In FIG. 1, all the mold members constituting the molding die 1 are closed, and a vulcanization molding is being carried out while holding a flowable rubber-like elastic material inside the cavity CV.

At the time of actual molding, other components such as a heating plate and a heat insulating plate for mounting on a press molding machine and fluidizing the rubber-like elastic material are necessary. Will be described together with a detailed molding method.

The upper mold 2, the middle mold 3 and the lower mold 4 are provided with a plurality of guide pins 5 and guide bushes 6 provided around the mold.
7 and can be opened independently of each other.

When the molding die 1 is compressed by the press molding machine, first, the middle die 3 and the lower die 4 are securely closed.
Then, a disc spring 8 having a large spring constant and a large urging force and a disc spring 9 having a small spring constant and a small urging force are positioned and provided by a pin 10 so that the upper mold 2 and the middle mold 3 are closed. .

When the press ram of the press forming machine is lowered and the compressive force applied to the forming die 1 is lost, these disc springs 8 and 9 are brought into close contact with the upper die 2, the middle die 3 and the lower die. It also exerts the effect of pressing the 4 to open the mold.

The middle mold 3 and the lower mold 4 are provided with annular cavities CV (formed by the cavity surface CV1 of the middle mold 3 and the cavity surface CV2 of the lower mold 4) for forming the O-ring R1. The cavities CV can be vertically divided in the figure by a parting line PL1 as a dividing surface, and the O-ring R1 can be released when the middle die 3 and the lower die 4 are open (see FIG. 2).

On the inner circumference side of the cavity CV, a gate section 11 is provided along the parting line PL1 over the entire circumference. Gate section 11 in this embodiment
Is about 0.04 mm in the mold opening direction, and the dimension S in the radial direction along the parting line PL1.
2 is about 0.03 mm.

The middle die 3 has an opening 12a (see FIG. 1) on the surface facing the upper die 2 of the middle die 3 and is connected to the gate portion 11, and the cross-sectional area is tapered from the opening 12a. A spool portion 12 having a cylindrical shape (a gradient angle of the outer peripheral side surface 12b with respect to the axial direction is about 10 degrees) is provided.

The outer peripheral side surface 12b of the spool portion 12
The inner peripheral side surface 12c is fixed to the upper die 2 and is formed by an outer peripheral surface of a substantially cylindrical core 13 protruding from the middle die 3.

The spool portion 12 near the gate portion 11 is a constricted portion 12d having a smaller cross section than the opening portion 12a, and is provided with a nozzle portion 14 extending from the constricted portion 12d to the gate portion 11.

The nozzle portion 14 directs the flow direction of the rubber-like elastic material flowing through the spool portion 12 toward the gate portion 11,
In addition, the flow is made smooth, and the shape is tapered toward the gate portion 11. In the nozzle portion 14 of this embodiment, the middle mold 3 is constituted by a tapered inclined surface 14a having an inclination angle of 60 degrees with the parting line PL1, and the lower mold 4 is constituted by an annular surface 14b.

The nozzle section 14 opens the upper mold 2 with the middle mold 3 and the lower mold 4 closed, and separates the upper mold 2 from the middle mold 3 from the parting line PL2 side. Is broken, and the O-ring R1, which is a product part, remains in the cavity CV.

Accordingly, the breaking strength of the molded rubber-like elastic material in the gate portion 11 is smaller than the breaking strength required when the molded rubber-like elastic material in the spool portion 12 is released from the middle mold 3. It is set as follows.

On the other hand, the upper mold 2 is provided with a pressurizing chamber 2a for holding and pressurizing the rubber-like elastic material so as to form a concave portion on the surface facing the middle mold 3.

An overflow gate 2b and a stagnation portion 2c for releasing the rubber-like elastic material overflowing from the pressurizing chamber 2a are provided along the parting line PL2 (see FIG. 3).

The overflow gate 2b allows the rubber-like elastic material to overflow during molding, and prevents the rubber-like elastic material from entering the outer periphery (parting line PL1) of the cavity CV without excessive pressure. This suppresses the occurrence of thin burrs on the O-ring R1.

The surplus rubber-like elastic material that has passed through the overflow gate 2b is stored in the retaining portion 2c.
If the thickness S3 of the overflow gate 2b is too large, the amount of the rubber-like elastic material that overflows increases, and the pressure applied to the spool portion 12 also decreases. Have been.

The outline of the molding process for molding the O-ring R1 using the molding die 1 will be described. The middle die 3 and the lower die 3 are completely closed, and are placed in the recesses of the pressure chamber 2a of the upper die 2. The heated rubber-like elastic material (rubber material) is fluidized by heating or the like, and the upper mold 2 is closed to fluidize the inside of the closed cavity CV via the spool unit 12 and the gate unit 11. The rubber-like elastic material is injected.

After the O-ring R1 is formed, the upper die 2 is opened, and the spool portion 12 is separated from the middle die 3 with the cavity CV closed, so that the spool portion 12 and the O-ring R1 are separated from each other at the gate portion 11. Then, the middle mold 3 and the lower mold 4 are opened to open the cavity CV, and the O-ring R1 is collected.

The use of the molding die 1 can prevent or suppress the occurrence of burrs in the O-ring R1 which has an extremely small wire diameter and is easily deformed. The manufacturing quality can be improved, and the O-ring R1 can be easily manufactured.

(Embodiment 2) FIG. 4 is a sectional view of an essential part for explaining a molding die 21 according to a second embodiment. Although the configuration around the cavity CV is shown in the figure, other configurations are the same as those in FIG. 1, and corresponding components are denoted by the same reference numerals.

The molding die 21 has an inner diameter of 0.5, for example.
This is a molding die for molding an extremely small O-ring R2 having a diameter of about 1.3 mm and an outer diameter of about 1.3 mm.

The structures of the cavities CV and the gate portion 11 are the same as those of the first embodiment shown in FIG. 1 (the dimensions and the like are different), but the spool portion 22 is not cylindrical but has a single tapered shaft. It is formed as a shape.

Further, the tip of the spool portion 22 is
a and a nozzle portion 23 having a spherical end portion 23b, and a gate portion 11 is connected to a boundary between the cylindrical portion 23a and the spherical end portion 23b.

The breaking strength of the gate 11
2, which is smaller than the breaking strength of the spool 22 when the spool 22 is separated from the middle mold 3.
Are separated.

As described above, it is possible to mold the extremely small O-ring R2 without generating burrs.

In the case of performing multi-cavity molding, the same spool portion 22 as indicated by a broken line H1
This can be achieved by forming a plurality of nozzle portions 23, gate portions 11, cavities CV, and the like.

FIG. 5 is a diagram showing a variation of a nozzle having a modified nozzle portion for the purpose of improving the formability and quality of the O-ring R2 and the breaking characteristics of the gate portion 11.

In FIG. 5 (a), the tip of the nozzle portion 24 is configured to be flush with the gate portion 11.
It is not necessary to consider the remaining nozzle portion in the portion ahead of the gate portion 11.

In the configuration shown in FIG. 5B, the length of the nozzle portion 25 before the gate portion 11 is set to be longer, and the spool portion 2
This is intended to take into consideration the fact that foreign matter or non-fluidized portion which tends to concentrate on the tip of the rubber-like elastic body flowing through 2 is shifted from the gate portion 11 and molded.

In FIG. 5 (c), the tip of the nozzle portion 26 is formed as a conical inclined surface 26a so as to allow the flowing rubber-like elastic body to smoothly enter the gate portion 11.

In adopting the shape of the nozzle portion shown in FIGS. 4 and 5, the optimum shape is changed depending on the size of the O-ring to be molded, the material of the rubber-like elastic material to be used, and the press molding machine. Therefore, an appropriate shape may be adopted.

(Embodiment 3) FIG. 6 is a sectional view of an essential part for explaining a molding die 31 according to a third embodiment. Although the configuration around the cavity CV is shown in the figure, other configurations are the same as those of the second embodiment referring to FIG.
Corresponding components have the same reference characters allotted.

This molding die 31 is a molding die for molding an extremely small O-ring R2 as in the second embodiment.

In order to smoothly guide the rubber-like elastic material to the gate portion 11, the nozzle portion 33 has conical inclined surfaces 33a, 33b which are tapered toward the gate portion 11.
It has.

The connecting portion of the spool portion 32 with the nozzle portion 33 is made smaller in cross section than the opening portion 32a on the side facing the upper die 2 of the middle die 3, and the spool portion 32 has the inclined surfaces 33a, Since it is expanded by 33b, it is a constricted portion 32b.

Further, a concave portion 33c for reducing the volume of the nozzle portion 33 is provided on the opposite side of the constricted portion 32b of the nozzle portion 33 (the lower mold 4 side).

Accordingly, in this embodiment, the injection of the rubber-like elastic material into the cavity is improved by the nozzle portion 33, and the concave portion 33c passes through the constricted portion 32b when the nozzle portion 33 is released from the mold. Deformation is allowed, the breakage of the nozzle portion 33 at the time of releasing is suppressed, and the releasing property can be improved.

Although the concave portion 33c has a conical shape in this embodiment, the concave portion 33c is not limited to this shape, and may have an appropriate shape such as a hemispherical shape, a truncated conical shape, or a cylindrical shape. It is possible to adopt the spool part 3
By effectively deflecting the flow of the rubber-like elastic material from 2 to the gate portion 11, it is also possible to improve the molding quality and the yield.

Further, as shown in FIG.
When the core 3 is used with a large peripheral diameter, the upper die 2 is opened before the spool portion 32 is pulled out, so that the nozzle portion 33 is also easily bent inward and the releasability is improved.

However, also in this case, the gate portion 11
By providing the annular concave portion 36 along the inner peripheral side of the roller, the releasability can be further improved, and the flow of the rubber-like elastic material from the spool portion 32 is deflected to the gate portion 11 (arrow A1). Direction) The effect of improving the molding quality can be exhibited.

Of course, there is no problem even if an annular recess is provided in the nozzle provided at the tip of the spool that does not use the core.

(Embodiment 4) In the fourth embodiment,
A method for forming the O-ring R2 using the forming die 21 described in the second embodiment will be described with reference to FIGS. FIG. 8 is a view showing a pre-forming step before setting the molding die 21 in the press molding machine, FIG. 9 is a view showing a molding step in which the molding die 21 is set in the press molding machine, and FIG. It is a figure which shows the post-molding process after taking out 21 from the press molding machine.

The pre-molding process is performed in steps A1 to A5, the molding process is performed in steps B1 to B3, and the post-molding process is performed in steps C1 to C1.
This will be described below as C4.

In the molding die 21, the O-ring R2
A plurality of cavities are provided so that a large number of molds can be formed at a time, and the upper mold 2, the middle mold 3, and the lower mold 4 which can be individually opened and overlapped with each other are provided.
Of the three-layer structure. Reference numeral 41 denotes a slide plate that supports the lower mold 4.

(Step A1) Upper die 2, middle die 3, lower die 4
Is opened, and a release agent is applied to the surfaces of the middle mold 3 and the lower mold 4 on which the cavities for forming the O-ring R2 are formed (FIG. 8A).

(Step A2) The middle mold 3 and the lower mold 4 are closed (FIG. 8B).

(Step A3) A release agent is applied to the mold opening surfaces of the upper mold 2 and the middle mold 3 (FIG. 8C).

(Step A4) A rubber cloth R1 made of a rubber-like elastic material is placed between the mold opening surfaces of the upper mold 2 and the middle mold 3 (FIG. 8D).

(Step A5) The upper mold 2 is closed (FIG. 8E).

In step A5, the pre-molding process of the mold 21 is completed. Here, a schematic configuration of a press molding machine PR holding the prepared molding die 21 and an incidental structure required for performing molding will be described.

The press molding machine PR is provided with a head 51 for compressing an object to be pressed in the axial direction, a press ram 52 and a bolster 53.

Ancillary structures necessary for molding include heat insulating plates 54 and 55 disposed between the head 51 and the bolster 53, an upper heating plate 56, a lower heating plate 57, a slide plate 41, and a protection plate 42. It is. Among these, the upper heating plate 56 and the lower heating plate 57 have a heat source for heating the mold 21.

(Step B1) The molding die 21 prepared in Steps 1 to 5 is loaded between the bolster 53 and the protection plate 42 at the lowered position of the press molding machine PR (FIG. 9).
(A)).

(Step B2) The press ram 52 is raised, and the molding die 21 is pressed to perform molding. At this time, the rubber cloth R1 is fluidized by conduction of heat from the upper heating plate 56 and the lower heating plate 57 (FIG. 9B).

(Step B3) When the rubber material R1 has sufficiently passed into each cavity and the molding is completed, the molding die 21
Then, the slide plate 42 is taken out from the press molding machine PR (FIG. 9C).

Next, with reference to FIG. 10, a post-molding process after removing the mold 21 from the press molding machine PR will be described.

(Step C1) After lowering the temperature of the molding die 21 taken out of the press molding machine PR, the upper die 2 is opened (FIG. 10 (a)).

(Step C2) The burrs BS of the spool portion appearing on the upper surface of the middle mold 3 are separated while the middle mold 3 and the lower mold 4 are closed. The burrs BS are separated from each other by a gate portion with the O-ring R2 (FIG. 10B).

(Step C3) The middle mold 3 is opened and inverted (FIG. 10C).

(Step C4) The O-ring R2 existing in the cavities of the opened middle mold 3 and the lower mold 4 is sucked and collected by the product collection blower 60 and the collection tube 61 (FIG. 10 (d), Product recovery blower 60
State))).

As described above, the burrs BS of the O-ring R2 can be collectively removed by the process described in the molding die 21 and steps A1 to C4, and the deburring operation can be eliminated or reduced. It becomes possible to easily manufacture an extremely small O-ring or an O-ring having a small wire diameter, for which deburring work has been difficult.

[0104]

According to the present invention, the deburring work of rubber products can be eliminated or greatly reduced, and productivity and production quality can be improved.

In particular, even in the case of an extremely small O-ring or an O-ring having a small wire diameter, burrs can be removed in the course of the molding process, and the O-ring can be easily manufactured.

By defining the breaking strength of the gate portion, the spool portion is separated from the second mold member so that the spool portion and the product portion can be separated from each other at the gate portion without leaving the spool portion on the second mold member. It becomes possible to separate them.

Since the gate portion is located on the inner peripheral side of the annular rubber product, even if thin burrs are generated on the divided surface other than the gate portion of the cavity, the thin rubber is located on the outer peripheral side of the annular rubber product, and the deburring operation is performed. It will be easier. Further, the configuration of the spool portion is simplified, and the workability of the mold can be improved.

The provision of the constricted portion in the spool portion, the nozzle portion, and the concave portion in the nozzle portion improves the injection property of the rubber-like elastic material into the cavity by the nozzle portion, and the concave portion forms the constricted portion when the nozzle portion is released from the mold. Thus, the deformation of the nozzle portion at the time of release can be suppressed by allowing deformation when passing through the nozzle, and the molding quality, yield, and releasability can be improved.

By providing a pressurizing chamber, an overflow gate, and a stagnant portion on the dividing surface between the first mold member and the second mold member, the first mold member and the second mold member can be formed at the time of molding. The rubber-like elastic material can overflow at the division surface between the second mold member and the third mold member where the product part of the rubber product is formed without excessive pressure. The entry of the elastic material is suppressed, and the occurrence of thin burrs in the product portion is suppressed. Further, in a molding method using a molding die for a rubber product, the first product is molded after the rubber product is molded.
The mold member is opened, and the spool portion is separated from the second mold member in a state where the cavity is closed, so that the spool portion and the product portion are separated from each other at the gate portion. By opening the mold and the third mold member to open the cavities and collecting the product part of the rubber product, burrs can be removed during the molding process, and the rubber product can be easily manufactured. Becomes

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a cross-sectional configuration of a molding die according to an embodiment of the present invention.

FIG. 2 is an enlarged view of a portion D1 in FIG. 1;

FIG. 3 is an enlarged view of a portion D2 in FIG. 1;

FIG. 4 is an essential part cross-sectional view for explaining a molding die according to a second embodiment.

FIG. 5 is a view showing a variation of a nozzle having a changed shape.

FIG. 6 is an essential part cross-sectional view for explaining a molding die according to a third embodiment.

FIG. 7 is an essential part cross-sectional view for explaining a modification of the molding die of the third embodiment.

FIG. 8 is a diagram showing a pre-forming step before setting a forming die in a press forming machine.

FIG. 9 is a view showing a molding step in which a molding die is set in a press molding machine.

FIG. 10 is a view showing a post-molding step after the mold is removed from the press molding machine.

FIG. 11 is a diagram schematically showing a cross-sectional configuration of a conventional molding die.

FIG. 12 is a diagram illustrating a punching jig.

FIG. 13 is a diagram for explaining a finishing defect due to a product shape of an O-ring.

[Explanation of symbols]

 1, 21, 31 Mold 2 Upper mold (first mold member) 2a Pressurizing chamber 2b Overflow gate 2c Retention chamber 3 Medium mold (second mold member) 4 Lower mold (third mold member) 5 Guide pin 6 , 7 guide bush 8, 9 disc spring 10 pin 11 gate part 12 spool part 12a opening part 12b outer peripheral side surface 12c inner peripheral side surface 12d constricted part 13 core 14 nozzle part 14a tapered inclined surface 14b annular surface CV cavity R1 O-ring ( Rubber product)

Claims (6)

[Claims] 1. A first, second and third mold members which are mold-openable and overlap one another in order, and said second mold member and a third mold for molding a product part of a rubber product. A cavity formed on a dividing surface between the members, a gate provided along the dividing surface of the cavity, and an opening on a surface of the second mold member facing the first mold member. A spool portion provided on a second mold member connected to the gate portion, wherein the rubber-like elastic material disposed between the first and second mold members is fluidized and the first mold member is fluidized. A molding die for a rubber product, in which a rubber-like elastic material fluidized through the spool portion and the gate portion can be injected into the closed cavity by closing the mold of the member. 2. The breaking strength of the molded rubber-like elastic material at the gate portion is determined by the value of the spool portion required when the rubber-like elastic material molded at the spool portion is released from the second mold member. The mold according to claim 1, wherein the mold is smaller than the breaking strength. 3. The molding die for a rubber product according to claim 1, wherein the gate portion is connected to an inner peripheral side of a cavity for molding an annular rubber product. 4. The spool portion includes a constricted portion having a cross section smaller than an opening of the spool portion, and a nozzle portion directed from the constricted portion to the gate portion. The mold according to any one of claims 1 to 3, further comprising a concave portion that allows deformation of the nozzle portion when passing through the constricted portion when the nozzle portion is released. 5. A pressurizing chamber having an opening of the spool on a dividing surface between the first mold member and the second mold member, and for holding and pressurizing a rubber-like elastic material. The molding die for rubber products according to any one of claims 1 to 4, further comprising an overflow gate and a retaining portion for allowing the rubber-like elastic material overflowing from the pressurizing chamber to escape. 6. A molding method using the molding die for a rubber product according to any one of claims 1 to 5, wherein after the rubber product is molded, the first mold member is opened. With the cavity closed, pull the spool
By separating from the mold member, the spool portion and the product portion are separated from each other at the gate portion. Thereafter, the second mold member and the third mold member are opened to open the cavity, and the product portion of the rubber product is collected. Molding method.