JP4632073B2 - Mold for sealing ring molding and molding method for sealing ring - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a mold for molding a seal ring in which an inner peripheral surface is elastically contacted and sealed to a piston rod, and an outer peripheral surface is elastically contacted and sealed to an inner peripheral surface of a cylinder, and a molding method using the mold About. The obtained seal ring is used for a brake master cylinder of an automobile.
[0002]
[Prior art]
A seal ring called a piston cup or packing is used in a brake master cylinder of an automobile. This seal ring is for generating hydraulic pressure for driving the brake. Seals between the inner peripheral surface of the seal ring and the piston rod and between the outer peripheral surface of the seal ring and the cylinder are extremely important. is there.
[0003]
Therefore, high surface accuracy is required for the inner peripheral surface and the outer peripheral surface, and it is necessary to prevent burrs from being generated in the portions during molding. However, rubber, which is the material of the seal ring, easily enters a small gap and easily generates burrs. Therefore, a conventional method for molding a seal ring is performed using a mold as shown in FIG.
[0004]
The mold includes a first mold 100 as an upper mold, a second mold 200 as a lower mold, and a third mold 300 as a middle mold. By the second mold 200, the lower surface and inner and outer peripheral surfaces of the seal ring 400 are formed. A sprue 101 is formed on the first mold 100, and the molding material is press-fitted into the cavity through a runner 102 formed between the second mold 200 and the mold. The third mold 300 and the first mold 100 are configured to form a U-shaped adhering portion 401 protruding from the upper end of the seal ring 400.
[0005]
When the mold is opened after molding using this mold, the adhering portion 401 is securely adhered to the third mold 300, so that the seal ring 400 is held in the third mold 300 together with the runner 102. Therefore, the mold can be easily released from the third mold 300 by pressing and elastically deforming the molded product with a pin or the like, so that the mold release can be automated.
[0006]
Since the adhesion part 401 and the runner 102 are integrated in the obtained molded product, the excision work is performed after mold release to form a seal ring. Therefore, when this mold is used, the runner 102 is formed on the inner peripheral surface of the seal ring 400 and the adhering portion 401 is formed on the outer peripheral surface. It is not positioned on the inner and outer peripheral surfaces.
[0007]
However, in the molding method using the above-mentioned mold, there is a problem that an extra part is required to be cut off after molding, which requires a large number of man-hours and a large material loss.
[0008]
Therefore, as a method for preventing the generation of burrs without forming an extra portion, a cavity-shaped mold as shown in FIG. 5 is also used. In other words, the shape of the cavity is the shape of the desired seal ring 400, and the molding material is pressed into the cavity by a pin gate or the like. A radial polishing pattern is applied to the mold parting surface, and the angle between the mold surface of the third mold 300 and the mold surfaces of the first mold 100 and the second mold 200 is set to an acute angle or an obtuse angle. As a result, the contact between the molds on the split surface becomes a line contact, and the clamping pressure increases. Accordingly, since the molding material can be prevented from entering the mold parting surface, the generation of burrs can be prevented, and the burring operation is not required.
[0009]
[Problems to be solved by the invention]
By the way, when the seal ring is formed, it is usually formed by a multi-cavity forming a plurality of workpieces with one mold. However, in that case, it is difficult to make the mold clamping pressures of all the cavities the same in all the cavities because of mold accuracy, and a part where the mold clamping pressure is low inevitably occurs. For this reason, even with the above-described mold structure, burrs may occur at portions where the clamping pressure is low. In addition, during the repetition of molding, the mold parting surface is likely to be worn, and burrs may occur at that part.
[0010]
Further, in a mold having a cavity as shown in FIG. 5, it is uncertain which mold of the first mold 100, the second mold 200, and the third mold 300 the seal ring 400 adheres to when the mold is opened after molding. . Therefore, the release of the seal ring 400 has to rely on human hands.
[0011]
Therefore, in the conventional molding method using a mold, it is difficult to perform full-automated molding because of the need to remove burrs or perform mold release manually. There is a problem that there is.
[0012]
The present invention has been made in view of such circumstances, and an object thereof is to enable full-automatic molding while preventing the occurrence of burrs.
[0013]
A feature of the mold for molding a seal ring of the present invention that solves the above-described problems is a mold for molding a ring-shaped seal ring having a seal surface that elastically contacts with a mating member on each of an inner peripheral surface and an outer peripheral surface. A first mold having a mold surface that forms one end surface of the ring, a second mold having a mold surface that forms the other end surface of the seal ring and an inner peripheral surface, and a first mold having a mold surface that forms an outer peripheral surface; The first mold is divided into an inner mold and an outer mold with a parting line located in one end surface, and the inner mold and the outer mold can move in the clamping direction. The inner mold and the outer mold are clamped independently, the inner mold is clamped with the second mold, and the outer mold is clamped with the third mold .
[0014]
In the above mold, it is preferable that the third mold has a concave portion or a convex portion on the mold surface so that the mold is released while the seal ring is held by the third mold when the mold is opened. Moreover, it is preferable that the mold surface forming the seal surface is formed at a position separated from all the mold split surfaces .
[0015]
Further, the sealing ring molding method of the present invention uses the above-described mold , press- molds the molding material into the cavity after clamping, and presses the molded product held in the third mold after opening the mold. To release from the mold.
[0016]
In the mold of the present invention, the first mold having a mold surface forming one end face of the seal ring is divided into an inner mold and an outer mold, and the mold dividing lines of the inner mold and the outer mold are located in one end face of the seal ring. ing. The inner mold and the outer mold are movable relative to each other in the mold clamping direction, the inner mold and the outer mold are clamped independently, the inner mold is clamped with the second mold, and the outer mold is clamped with the third mold. It is configured to be clamped .
[0017]
Therefore, according to the mold of the present invention, when the mold is clamped, the outer mold is clamped independently from the third mold. Therefore, when a large number of molds are taken, the mold between the outer mold and the third mold is caused by distortion of the mold. The inner mold and the outer mold can be clamped with the second mold and the third mold with substantially the same force without lowering the clamping force. As a result, each part of the first mold, the second mold, and the third mold can be clamped with substantially the same pressure, and it is possible to reliably prevent the molding material from entering the mold split surface and prevent the generation of burrs. can do. The positions of the inner mold and outer mold dividing lines are not particularly limited as long as they are within one end face of the seal ring.
[0018]
It is preferable that the third mold has a concave portion or a convex portion on the mold surface and is configured to be released from the mold while the seal ring is held by the third mold when the mold is opened. By doing so, it becomes possible to press the work held in the third mold after the mold is opened and release from the third mold, and no burr is generated as described above. It becomes possible. Accordingly, the man-hours for forming the seal ring are reduced, and the material loss is also reduced, so that a significant cost reduction is possible.
[0019]
The shape of the concave portion or convex portion is formed so that the seal ring is released while being held by the third die, and is undercut to the extent that it can be released from the third die by elastic deformation due to axial pressing. If it does, the shape, such as a dot shape and a ring shape, will not be restricted. Further, in the case of the concave portion, a convex portion is formed on the outer peripheral surface of the seal ring. By forming the convex portion in a ring shape, it is possible to provide a seal surface that elastically contacts the counterpart material.
[0020]
It is also preferable that the mold surface forming the sealing surface is formed at a position spaced from the mold splitting surface. Thereby, even if a burr | flash generate | occur | produces, it can be made small so that the influence which acts on sealing performance can be disregarded. Furthermore, it is desirable that the angles between the mold surfaces that are pressed against each other are not substantially acute or obtuse, but are substantially perpendicular. As a result, the life of the mold can be extended and further cost reduction can be achieved.
[0021]
In order to mold a seal ring using the above-described mold of the present invention, first, the first mold, the second mold, and the third mold are clamped. In the conventional mold, there is a case where a part of the mold is lifted due to the distortion of the mold and the clamping force is partially reduced. However, in the mold according to the present invention, the first mold is divided into the inner mold and the outer mold, and each mold is clamped independently. Therefore, there is no problem that the clamping force is partially reduced. Therefore, the molds are clamped with a substantially constant force.
[0022]
Then, a molding material made of rubber or soft resin is pressed into the cavity. Since each mold is clamped with almost the same pressure, the molding material is prevented from entering the split surface of the mold and the generation of burrs is prevented.
[0023]
When the mold is opened after molding, the concave or convex portion of the mold surface of the third mold is undercut, so that the seal ring is exposed while being securely held by the third mold. Therefore, when the seal ring is pressed in the axial direction with an extrusion pin or the like, the seal ring is soft and easily elastically deformed to be released from the third mold and fall in a certain direction. Therefore, even if a large number are taken, all the seal rings can be dropped in the same direction. Further, no burrs are generated, and it is not necessary to form an extra portion, so that a cutting step is not necessary.
[0024]
Therefore, according to the molding die and molding method of the present invention, the generation of burrs is reliably prevented, so that it is possible to form fully automatically, not limited to single-piece or multi-piece picking, greatly increasing the manufacturing cost. Can be reduced.
[0025]
【Example】
Hereinafter, the present invention will be described specifically by way of examples.
[0026]
FIG. 1 shows a cross-sectional view of a rubber seal ring obtained by the mold and molding method of this embodiment. This seal ring 1 is used for a brake master cylinder, and one end face 10 is formed to be substantially flat. A ring-shaped groove portion 11 having a substantially V-shaped cross section is formed on the end surface opposite to the one end surface 10, and an inner portion 12 and an outer portion 13 are formed on both sides of the groove portion 11. Further, a ring-shaped inner peripheral ridge 14 projecting inward is formed on the inner peripheral surface of the inner part 12, and a ring-shaped outer peripheral ridge 15 projecting outward is formed on the outer peripheral surface of the outer part 13. ing. A plurality of protrusions 16 are formed on the one end face 10 side of the outer peripheral protrusion 15. The inner peripheral ridge 14 is elastically contacted with the piston rod, and the outer peripheral ridge 15 is elastically contacted with the inner peripheral surface of the cylinder and functions as a sealing surface. The presence of the groove portion 11 facilitates elastic deformation of the inner portion 12 and the outer portion 13.
[0027]
FIG. 2 shows a cross-sectional view of the main part of the mold used in this example. The mold is composed of a lower mold 2, a middle mold 3, and an upper mold 4. The lower mold 2 has a mold surface for molding the one end surface 10 and the inner peripheral surface of the inner portion 12. The mold surface forming the inner peripheral surface of the inner part 12 of the lower mold 2 includes a straight part 20 extending substantially perpendicularly from the mold dividing surface of the upper mold 4 and the middle mold 3, and an inner peripheral ridge continuous with the straight part 20. A ring-shaped concave groove 21 for forming the portion 14 is formed.
[0028]
The middle mold 3 has a mold surface for molding the outer peripheral surface of the outer portion 13. The mold surface includes a straight portion 30 extending substantially perpendicularly from the mold splitting surfaces of the upper die 4 and the lower die 2, and a ring-shaped concave groove for forming the outer peripheral ridge portion 15 continuous with the straight portion 30. 31 and a plurality of dot-like recesses 32 are formed.
[0029]
Further, the upper mold 4 is divided into two, an inner mold 40 having a mold surface that molds the end surface of the inner portion 12 and the groove portion 11, and a cylindrical outer mold 41 that molds the end surface of the outer peripheral portion 13. The outer mold 41 can be clamped independently of each other. A sprue 42 is formed in the inner mold 40, and a pin gate 43 that connects the sprue 42 and the cavity 5 is formed.
[0030]
A plurality of such cavities 5 are formed in the mold, and a large number can be obtained.
[0031]
Hereinafter, a method for forming the seal ring 1 using the mold will be described.
[0032]
First, the lower mold 2, the middle mold 3 and the upper mold 4 are clamped as shown in FIG. At this time, if the upper mold 4 is not a two-part structure, but the inner mold 40 and the outer mold 41 are integrated, the inner mold 40 and the outer mold 41 are either the middle mold 3 or the lower mold due to distortion of the mold. 2 and the clamping force are partially different. For example, the pressure contact force between the outer die 41 and the middle die 3 may be weakened. In such a case, the molding material may partially enter the parting surface to generate burrs. In such a case, deburring work is required after molding.
[0033]
However, in the mold of the present invention, the upper mold 4 is divided into an inner mold 40 and an outer mold 41, and each can be clamped independently. Therefore, even if the mold is distorted, the distortion is absorbed by the relative movement between the inner mold 40 and the outer mold 41, and the inner mold 3 and the lower mold 2 are almost the same in the inner mold 40 and the outer mold 41. And clamped.
[0034]
Therefore, since the molding material press-fitted into the cavity 5 from the sprue 42 and the pin gate 43 does not enter the mold split surface, generation of burrs is prevented. In addition, the mold surfaces that continue from the mold dividing surface to the cavity 5 are straight portions 20 and 30 that are substantially perpendicular to the mold dividing surface, respectively. Therefore, since the concentration of stress is relaxed, wear during repeated use is small, and burrs are prevented from being generated after repeated use.
[0035]
After the molding material filling the cavity 5 is solidified, the lower mold 2, the middle mold 3 and the upper mold 4 are separated from each other. Then, since the groove 31 and the plurality of recesses 32 are undercut with respect to the mold opening direction, the seal ring 1 is held in the middle mold 3 as shown in FIG.
[0036]
In this state, an unillustrated push pin protrudes from the upper part of the middle mold 3 and presses the seal ring 1. Then, the seal ring 1 is elastically deformed and is easily released from the middle mold 3 and automatically taken out.
[0037]
Therefore, according to the molding method of the present embodiment, the seal ring 1 without burrs can be molded fully automatically without using manpower, so that the number of man-hours is greatly reduced. In addition, the deburring operation is unnecessary, and the material loss is only the portion formed by the sprue 42, so that the material loss is greatly reduced. As a result, significant cost reduction can be achieved.
[0038]
【The invention's effect】
That is, according to the seal ring molding die and seal ring molding method of the present invention, a seal ring without burrs can be molded fully automatically, so that man-hours and material loss can be greatly reduced. .
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a seal ring formed in an embodiment of the present invention.
FIG. 2 is a cross-sectional view of an essential part showing a mold according to an embodiment of the present invention in a clamped state.
FIG. 3 is a cross-sectional view of an essential part showing a mold according to an embodiment of the present invention in a state of releasing a seal ring.
FIG. 4 is a cross-sectional view of a main part showing a conventional mold together with a molded body.
FIG. 5 is a cross-sectional view of a main part of another conventional mold.
[Explanation of symbols]
1: Seal ring 2: Lower mold (second mold) 3: Medium mold (third mold)
4: Upper mold (first mold) 40: Inner mold 41: Outer mold

Claims (4)

A mold for forming a ring-shaped seal ring having a seal surface elastically contacting with a mating member on each of an inner peripheral surface and an outer peripheral surface, the first die having a mold surface forming one end surface of the seal ring; A second mold having a mold surface forming the other end face of the seal ring and the inner peripheral surface, and a third mold having a mold surface forming the outer peripheral surface and disposed between the first mold and the second mold. And more
The first mold is divided into an inner mold and an outer mold in which a parting line is located in the one end surface, and the inner mold and the outer mold are movable relative to each other in a mold clamping direction, and the inner mold and the outer mold are separated from each other. Wherein the inner mold is clamped with the second mold, and the outer mold is clamped with the third mold. Type.   The said 3rd type | mold has a recessed part or a convex part in the type | mold surface, It was comprised so that it might be mold-released in the state which the said seal ring was hold | maintained at the said 3rd type | mold at the time of mold opening. A mold for forming a seal ring as described in 1.   The mold for forming a seal ring according to any one of claims 1 to 2, wherein the mold surface forming the seal surface is formed at a position spaced apart from all the mold split surfaces.   Using the seal ring molding die according to any one of claims 2 to 3, a molding material is press-fitted into the cavity after clamping, and the molded product held in the third mold is pressed after the mold is opened. A fully automated method for forming a seal ring, wherein the mold is released from the third mold.

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