JPH0780188B2 - Rubber molding dies - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber molding die used for molding a rubber molding by injection molding or injection molding. INDUSTRIAL APPLICABILITY The mold of the present invention can be used when forming a terminal portion or a corner portion by injection molding on a weather strip formed by extrusion molding.

[0002]

2. Description of the Related Art In injection molding or injection molding of rubber,
The molding material enters the PL surface of the mold to cause burrs. Therefore, in order to reduce the number of steps for removing this burr, a gripping cavity that can be gripped is provided along the dividing portion (PL) through a narrow cavity having a molding thickness of 0.1 to 0.2 mm, and the gripping portion after molding is formed. The burrs are removed by holding them and tearing them off with a hand groove.

When a corner portion having a different cross-sectional shape is formed by die molding on a weather strip formed by extrusion, the extruded body is inserted and held from both sides of the die, and the inside of the die is held. Connect by molding by injection molding. At this time, it is necessary to inject a larger amount than the required amount so that insufficient injection of the molding material does not occur. However, if the injection amount is large, pressure is applied to the extruded product, causing defects such as deformation. Therefore, at the position where the molding material of the cavity reaches the end,
An overflow cavity is provided to receive excess molding material.

[0004]

Conventionally, it is considered most effective that the overflow cavity is directly communicated with the main cavity, and the molding material is easy to flow from the main cavity without applying extra pressure to the extrusion molded body. It is usually formed in a plate shape having a molding thickness (gap) of 0.5 to 1.5 mm. Therefore, the overflow portion formed by the overflow cavity cannot be removed by hand and the operator is currently cutting it off with scissors. Therefore, the man-hour of excision becomes large.

Further, when scissors are used, the traces of excision become ugly, so that the overflow cavity cannot be provided in the portion which becomes the design surface. Therefore, the pressure acting on the portion of the design surface that is connected to the extruded product may be high, and it is necessary to firmly hold the extruded product at that part, which complicates the mold structure. There is a problem with.

The present invention has been made in view of such circumstances, and it is an object of the present invention to improve the mold structure so that the use of scissors becomes unnecessary.

[0007]

As a result of various studies on the shape of the overflow cavity, the inventors of the present invention have found that the molding thickness (gap) need not be increased to 0.5 to 1.5 mm as in the conventional case. , Has been found to function well as an overflow cavity. Then, they have found that it is sufficient to partially equalize the narrow cavity, and completed the present invention.

That is, the rubber molding die of the present invention which solves the above-mentioned problems is provided with a main cavity, a narrow cavity communicating with the main cavity along the divided portion of the main cavity to form a hand groove, and a narrow cavity communicating with the narrow cavity. In a rubber molding die having a hand-pulling cavity for molding the hand-plucked portion and an overflow cavity communicating with a part of the main cavity for receiving an excess of the molding material, the overflow cavity communicates with the hand-pulling cavity. With
Molding thickness communicating with narrow cavity is 0.1-0.2m
It is characterized in that it communicates with the main cavity through a connection cavity of m.

The main cavity is a cavity for molding the molded body itself. The narrow cavity is a cavity that forms a hand groove, and can be configured in the same manner as the conventional one. The thickness of the hand grip groove is 0.1 to 0.2 mm so that the hand grip groove can be torn off by hand.
Must be formed so that This thickness is 0.1m
When the thickness is less than m, it becomes difficult to fill the hand-wound groove and the hand-whip portion with the molding material, and it becomes difficult to hand-wipe. Further, even if the thickness exceeds 0.2 mm, it becomes difficult to peel the hand. This narrow cavity is provided in the PL portion along the main cavity.

The hand grip cavity is provided along the narrow cavity so as to communicate with the narrow cavity, and forms the hand grip portion as in the conventional case. The overflow cavity is a portion that receives an excessive amount of the molding material, and is provided at a position where the molding material reaches the end similarly to the conventional case. At an intermediate position, the molding material first fills the overflow cavity and then the end portion of the main cavity, and there is no point in providing the overflow cavity.

The most important feature of the present invention is that the overflow cavity has a molding thickness of 0.1 to 0.2 mm, which communicates with the hand gripping cavity and also with the narrow cavity.
It is in communication with the main cavity through the connection cavity of. By providing the connection cavity in this manner, the overflow portion formed by the overflow cavity can be removed by hand scraping at the connection portion formed by the connection cavity, and cutting by scissors can be eliminated. If this molding thickness becomes less than 0.1, it becomes difficult for the molding material to flow into the overflow cavity,
It cannot function as an overflow cavity. On the other hand, if it exceeds 0.2 mm, it becomes difficult to rub hands and it is unavoidable to use scissors.

[0012]

With the rubber molding die of the present invention,
The molding material fills the gripping cavity from the main cavity through the narrow cavity and the excess finally flows into the overflow cavity through the connecting cavity.
As a result, the pressure from the molding material is prevented from being transmitted to the extruded body or the like inserted in the mold, and the deformation of the extruded body or the like is prevented.

Then, in the obtained molded product, the hand gripping portion and the overflow portion can be removed by the hand gripping at the hand gripping groove and the connecting portion. Therefore, a cutting process using scissors is unnecessary, and the number of steps can be reduced. Also, since the surface removed by the hand scraping is clean, even if the overflow portion is on the design surface, it does not impair the appearance. Therefore, the degree of freedom in the position of the overflow cavity is improved,
High degree of freedom in design.

[0014]

EXAMPLES The present invention will be specifically described below with reference to examples. Figure 1
4 shows a molding die according to an embodiment of the present invention. This mold has two types of weather strips 100, 20 with irregular cross sections.
It is used when the connection part of 0 is formed by injection molding.

This molding die is composed of an upper mold 1, a middle mold 2, and a lower mold 3. The plunger 11 presses the molding material charged in the pot 10 provided in the upper mold 1, and the sprue 12 and Injection molding is performed by press-fitting from the gate 13 into the cavity 4. The gate 13 is provided at the central portion in the axial direction of the connecting portion. Here cavity 4
Is a main cavity 40 forming the entire connecting portion, a plurality of narrow cavities 41 communicating with the main cavity along the PL portion of the main cavity 40, a hand-holding cavity 42 communicating with the narrow cavity 41, and a main cavity 40 Four overflow cavities 4 provided in pairs at both ends in the axial direction and communicating with the hand cavity 42.
3 and 3. The narrow cavity 4 is provided between the overflow cavity 43 and the main cavity 40.
There is a connection cavity 44 communicating with 1.

The narrow cavity 41 has a molding thickness of 0.1 to 0.1.
It is 0.2 mm and forms a handheld groove. And the hand cavity 42 communicating with the narrow cavity 41 is
It has a molded thickness of 1.5 mm and a width of 2 mm, and forms a gripped portion that can be gripped by an operator and has sufficient strength. The overflow cavity 43 has a molding thickness of 1.5 mm and is formed in a size sufficient to accommodate an excess molding material. Further, the connecting cavity interposed between the overflow cavity 43 and the main cavity 40 has a molding thickness (gap) of 0.15 mm and forms a thin connecting portion. Therefore, the overflow portion formed by the overflow cavity 43 can be gripped and gripped by the connecting portion.

In the molding die of this embodiment configured as described above, first, two types of weather strips 100 and 200, which are respectively formed by extrusion molding in advance, are inserted into the mold, and the respective end faces are mainly formed. It is held and fixed at a position exposed in the cavity 40. Next, the plasticized rubber molding material is put into the pot 10, and the plunger 11 is moved forward to press the molding material into the cavity 4.

The molding material press-fitted from the gate 13 advances from the center of the main cavity 40 toward the end. Then, the narrow cavity 41 and the hand-holding cavity 42 formed in the PL portion are filled, the entire main cavity 40 is filled, and the excess molding material is added to the connecting cavity 4
From 4 into the overflow cavity 43, the injection is completed.

Next, after heating and vulcanization, the mold is opened to form a molded body integrally joined to the weather strips 100 and 200. Then, the operator holds this molded body and picks up the hand grip portion formed by the hand grip cavity 42 or the overflow portion formed by the overflow cavity 43, and the hand grip groove formed by the narrow cavity 41 and the connection cavity 44 By tearing off at the formed connecting portion, a connecting member having an excellent appearance can be obtained.

Therefore, according to the molding die of this embodiment, scissors are not required for removing the overflow portion, so that the number of removing steps is small. In addition, since the removal traces are clean, an overflow portion can be provided on the design surface, deformation of the joint portion can be prevented, and flexibility in design is high.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a molding die according to an embodiment.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is an enlarged view of a main part of FIG.

FIG. 4 is a sectional view taken along line BB of FIG.

[Explanation of symbols]

40: Main cavity 41: Narrow cavity 4
2: Hand cavity 43: Overflow cavity 44: Connection cavity

Claims (1)

[Claims] 1. A main cavity, a narrow cavity for communicating with the main cavity along a divided portion of the main cavity to form a hand grip groove, and a hand cavity for communicating with the narrow cavity and forming a hand grip portion. A rubber molding die having an overflow cavity communicating with a part of the main cavity and receiving an excess amount of a molding material, the overflow cavity communicating with the hand gripping cavity and communicating with the narrow cavity. A rubber molding die, which is communicated with the main cavity through a connection cavity having a molding thickness of 0.1 to 0.2 mm.