JPH025934Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a rubber molding die for forming a molded article from a highly elastic rubber material. The present invention can be used for molding engine mounts, cushion rubber, etc. used in automobiles.

[Prior Art] Conventionally, improvements have been made to molds for rubber molding in order to ensure that runners are attached to predetermined split molds when the mold is opened.

This will be explained below by taking as an example a rubber molding mold consisting of three divided molds shown in FIG. In this case, the unvulcanized compounded rubber is placed in the first divided mold 10.
0 sprue hole 101, then second split mold 1
02 and the first split mold 100 through the runner hole 104 formed in the mold part surface 103.
04 is injected into the end of the cavity 106 through the gate hole 105 provided at the tip. and cavity 1
After the unvulcanized compounded rubber in 06 is vulcanized and hardened, the mold parting surface 103 is opened as shown in FIG. 5, and the sprue 101a filled in the sprue hole 101,
Runner 104 filled in runner hole 104
a, gate 105a filled in gate hole 105
was attached to the first split mold 100 side, and the tip 105b of the gate 105a was torn off using the mold opening force when opening the mold splitting surface 103 to separate the gate 105a and the rubber product 106a. . After separation, the mold parting surface 107 was opened and the rubber product 106a inside the cavity 106 was taken out.

In the above-mentioned rubber molding mold, as shown in FIG. 5, in order to tear off the gate 105a at the tip 105b, the runner 104a and hence the gate 105a must be firmly attached to the first split mold 100 side. For this purpose, an extra sprue lock hole 108 is formed at the tip of the runner hole 104 as shown in FIG. This sprue lock hole 108 is also filled with unvulcanized compounded rubber to form a sprue lock 108a.
a, the runner 104a is placed in the first divided mold 1.
I tried to make sure that it adhered to 00.

[Problems to be Solved by the Invention] However, the sprue lock 108a requires a considerable volume in order to securely attach the runner 104a to the first split mold 100. Furthermore, the formation of the sprue lock 108a caused a problem in terms of yield.

The present invention was made to solve this problem, and its purpose is to create a mold for rubber molding that can more reliably attach the runner to a predetermined split mold without being disadvantageous in terms of yield. It is on offer.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention forms an undercut portion in the runner hole connected to the gate hole, and when the mold is opened, the runner is placed in a predetermined position. It was made to be firmly gripped by the split type.

That is, the mold for rubber molding according to the present invention is composed of at least two divided molds, with a sprue hole formed in one divided mold, and a sprue hole formed in the split surface of the divided mold with one end formed in the sprue hole. A rubber molding device having a runner hole that communicates with the mold, a cavity that is formed in the split mold and defines the shape of the rubber product, and a gate hole that has one end that communicates with the other end of the runner hole and the other end that communicates with the cavity. In the mold, at least a part of the runner hole connected to the gate hole is provided with an undercut portion that becomes wider as it goes from the split surface side of the split mold toward the inside of the mold, and the runner hole is filled with rubber. The runner who was
This is characterized in that the undercut portion adheres to the formed split mold when the mold is opened.

The term "runner hole" used herein refers to a passage formed in the split surface of the split die that leads the unvulcanized compounded rubber from the sprue hole to the gate hole.

The undercut portion refers to a portion of a split mold that has a shape that becomes wider as it goes toward the inside of the mold from the mold surface side. The undercut portion may be formed over the entire length of the runner hole, or may be formed only in a portion of the runner hole on the gate hole side. It is generally preferable that the angle of inclination of the undercut portion with respect to the mold parting surface (the angle .theta. illustrated in the embodiment of FIG. 3) is 70 to 80 degrees. The angle of inclination of the undercut may be uniform over the entire length of the undercut. Also, by reducing the inclination angle on the gate hole side, the runner on the gate hole side can be
Separate molds with undercuts may be used to ensure reliable attachment.

In the present invention, the undercut portion is formed so that the cross-sectional area of the runner hole of the conventional rubber molding mold does not differ from the cross-sectional area of the runner hole of the rubber molding mold of the present invention in which the undercut portion is formed. Form.

[Function] In the rubber molding mold according to the present invention, first, the fourth
Similarly to the conventional method shown in the figures and FIG. 5, unvulcanized compounded rubber is injected into the cavity through the sprue hole to fill it. After the unvulcanized compounded rubber is vulcanized and hardened,
Open the split surface of the split mold and take out the rubber product inside the cavity.

In addition, when opening the mold, in the present invention, the runner is reliably attached to the split mold having the undercut portion.

The runners attached to the split molds with undercuts are made of rubber and are highly elastic. Therefore, even though the undercut portion is formed, the runner can be separated from the undercut portion of the runner hole.

[Effects of the invention] In the rubber molding mold according to the invention, the runner can be attached to a predetermined split mold without providing a conventional sprue lock. This eliminates the need for a large volume sprue lock, which is advantageous in terms of yield.

[Example] The present invention will be described in more detail with reference to the example shown in FIGS. 1 to 3. Fig. 1 is a sectional view showing the state in which the first split mold and the second split mold are opened after curing the unvulcanized compounded rubber, and Fig. 2 is a sectional view of the rubber molding mold of this example. FIG. 3 is an enlarged sectional view taken along the - line in FIG. 2.

(Structure of Example) The mold for rubber molding of this example is composed of a first divided mold 1 as a fixed mold, and a second divided mold 2 and a third divided mold 3 as movable molds. ing.
Here, 4 is a mold dividing surface between the first divided mold 1 and the second divided mold 2, and 5 is a mold dividing surface between the second divided mold 2 and the third divided mold 3. A cavity 9 is formed in the mold cutting surface 5 to define the shape of the rubber product. This cavity 9 is for molding cushion rubber as a rubber product. As shown in FIG. 2, the first split mold 1 is formed with a sprue hole 6 that extends through the first split mold 1 in the mold opening direction and expands toward the mold split surface 4. . A runner hole 7 is formed in the die cutting surface 4 in a direction intersecting the sprue hole 6. Here, one end 7a of the runner hole 7 is formed to communicate with the sprue hole 6. A gate hole 8 is formed in the second split mold 2 so as to pass through the second split mold 2 in the mold opening direction. The gate hole 8 is formed to become narrower toward the cavity 9. Therefore, the part connected to the cavity 9, that is, the gate hole 8
The opening area of the tip 8a is the smallest. One of the reasons why the opening area of the tip 8a of the gate hole 8 is made the narrowest is that the tip 8a is torn off and separated from the rubber product 90.

Now, in this embodiment, from one end 7a of the wall surface forming the runner hole 7 to the other end 7b, the third
Undercut portions 10 and 11 as shown in the figure are formed. The undercut portions 10 and 11 are formed from the mold splitting surface 4 side of the first split mold 1.
As we move toward the inside of the divided mold 1, that is, the third
It is formed so that it becomes wider as it goes in the direction of arrow A in the figure. In this embodiment, the inclination angle θ of the undercut portions 10 and 11 with respect to the mold cutting surface 4 was set to 75 degrees.

In this example, molding is performed as follows. First, a mold for rubber molding is clamped as shown in FIG. Then, unvulcanized compounded rubber is injected into the sprue hole 6 from a nozzle (not shown). Then, this unvulcanized compounded rubber passes through the runner hole 7 and the gate hole 8, flows into the cavity 9, and is filled into the cavity 9. Then, the unvulcanized compounded rubber is cured by vulcanization. Then, the rubber product 90 with the cavity 9 filled with unvulcanized compounded rubber, the sprue 60 formed by filling the sprue hole 6 with unvulcanized compounded rubber, and the runner hole 7 filled with unvulcanized compounded rubber. A gate 80 is formed by filling the formed runner 70 and gate hole 8 with unvulcanized compounded rubber.

Next, as shown in FIG. 1, the mold parting surface 4 is opened in the mold release direction. Then, in this embodiment, an undercut portion 10 is formed from one end 7a of the runner hole 7 to the other end 7b.
Since the undercut portion 11 is formed, the runner 70 is pulled toward the first split mold 1 side as shown in FIG. It is pulled to the 1 side of the divided mold 1. On the other hand, at this stage, as shown in FIG.
remains filled in the cavity 9. Therefore, due to the mold opening force when opening the mold cutting surface 4, the gate 80 is automatically cut at the tip 80a, which has the lowest strength.

Here, if the runner 70 does not reliably adhere to the first split mold 1, the following problem will occur. That is, if the runner 70 and the gate 80 adhere to the second split mold 2, the tip 80a of the gate 80 and the rubber product 90 cannot be automatically separated using the mold opening force of the mold splitting surface 4. A problem arises. In this regard, in this embodiment, since the undercut parts 10 and 11 are formed, the runner 70, as shown in FIG.
The sprue 60 and the gate 80 are securely attached to the first divided mold 1. Therefore, the tip 80a of the gate 80 and the rubber product 90 can be automatically separated using the mold opening force, which is convenient in terms of promoting automation.

As described above, after separation at the tip 80a of the gate 80, the second divided mold 2 and the third divided mold 3 are opened, although not shown, and thereby the second divided mold 2 and the third divided mold 3 are separated. A space is formed between the mold 3 and the rubber product 90 from the cavity 9 through this space.
Take out.

Note that the runner 70 attached to the first split mold 1
Since it is made of rubber and has high elasticity, even if the undercut parts 10 and 11 are formed, it can be forcibly released from the runner hole 7 with an extrusion pin or a fingertip.

(Effects of Example) As described above, in this example, the runner 70 can be reliably attached to the first split mold 1 by the undercut parts 10 and 11. Therefore, the tip 80a of the gate 80 and the rubber product 90 can be automatically separated using the mold opening force.

Further, since the cross-sectional area of the runner hole 7 is not different from the cross-sectional area of the conventional runner hole 104 shown in FIG. 4, the large-volume sprue lock 108a is not required, which is advantageous in terms of yield.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of a rubber molding mold showing a state in which the first divided mold and the second divided mold are opened after curing the unvulcanized compounded rubber, and Figure 2 is a cross-sectional view of the mold for rubber molding, showing the state in which the first divided mold and the second divided mold are opened. A cross-sectional view of the rubber molding mold in the state shown in Fig. 3 is as follows.
FIG. 3 is an enlarged sectional view taken along the line - in FIG. 2; Figures 4 and 5 show conventional rubber molding molds, Figure 4 is a diagram equivalent to Figure 2, and Figure 5 is a diagram equivalent to Figure 1.
It is a figure equivalent figure. In the figure, 1 is the first divided type, 2 is the second divided type,
3 is a third split mold, 4 and 5 are mold dividing surfaces, 6 is a sprue hole, 7 is a runner hole, 8 is a gate hole, 9 is a cavity, 60 is a sprue, 70 is a runner, 8
0 indicates a gate, and 90 indicates a rubber product.

Claims (1)

[Claims for Utility Model Registration] (1) Consists of at least two split molds, with a sprue hole formed in one split mold, and a sprue hole formed in the split surface of the split mold, with one end communicating with the sprue hole. A mold for rubber molding, the mold having a runner hole formed in the split mold to define the shape of the rubber product, and a gate hole having one end communicating with the other end of the runner hole and the other end communicating with the cavity. At least a part of the runner hole connected to the gate hole has an undercut portion that becomes wider as it goes from the mold surface side of the split mold toward the inside of the mold, and the runner hole is filled with rubber. A mold for rubber molding, characterized in that the formed runner is attached to the split mold in which the undercut portion is formed when the mold is opened. (2) The mold for rubber molding according to claim 1, wherein the runner hole has an undercut portion along its entire length. (3) There are three split molds, the sprue hole passes through the first split mold, and the runner hole is formed in the mold splitting surface of the first split mold and the second split mold. , the cavity is formed on the split surfaces of the second split mold and the third split mold, and the undercut portion extends from the mold split surface side of the first split mold to the mold of the first split mold. The gate hole is formed so as to become wider toward the inside, and the gate hole passes through the second divided mold, and the opening area of the portion of the gate hole that connects to the cavity is configured to be the smallest. A mold for rubber molding according to claim 1 of the utility model registration claim.