JPS5835462B2 - Molding mold for rubber cylindrical products - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mold for forming a cylindrical molded product made of rubber, and more specifically, a mold for molding a cylindrical molded product made of rubber, and more specifically, a mold for molding a cylindrical molded product made of rubber. Regarding molding molds.

Conventionally, a seal ring 1 as shown in FIG. 2 (for example, for an automobile disc brake) has been manufactured by cutting a cylindrical rubber molded product 2 in the circumferential direction as shown in FIG. 1.

In order to mold this cylindrical molded product 2, there is also a method using extrusion, but it requires an expensive extruder and
It requires polishing work to remove the burrs after mold vulcanization of the extruded cylindrical molded product, making it unsuitable for small-scale production.

For this reason, when producing in small quantities, a single trust fabric system as shown in FIGS. 3 to 6 was used.

That is, after placing the rubber material M on the upper surface of the pot part 5 disposed directly above the cylindrical cavity part 3, or the cylindrical core part 6 in the illustrated example, as shown in FIG. The rubber material M is injected into the cavity part 3 while being compressed by a plunger part 9 formed in the upper die 8, and finally the injection of the rubber material M into the cavity part 3 is completed as shown in FIG.

At this time, the rubber material M may not be placed at the center of the core part 6, and therefore, during the process of injecting the rubber material into the cavity part 3, as shown in FIG. The injection heights are different, and a gap S as shown in FIG. 6 is created just before the injection is completed, and a fused portion is formed in the molded product.

This fused portion was weaker in strength than other portions and could not be used when manufacturing seal rings.

In addition, during the injection process, it is necessary to remove the air stored at the bottom of the cavity 3, but this air removal is performed from above the cavity 3 by opening and closing the mold, so the depth of the cavity 3 cannot be increased, and the Only a cylindrical body (approximately 20 m or less) could be formed.

In view of the above, the present invention is directed to a one-transfer type molding die, and when molding a cylindrical molded product, a fusion part is not formed at the bottom of the cylindrical molded product, and the axis is different from that in the past. To provide a molding die for a cylindrical rubber molded product, which can mold a long molded product in the direction and improve the yield when cutting the molded product to produce a seal ring or the like.

The gist of the invention is that the pot has a cylindrical cavity, the lower end opening of the pot disposed directly above the cavity is narrowed to be smaller than the outer diameter of the cylindrical core forming the cavity, and the pot has a cylindrical cavity. Molding of a cylindrical rubber molded product, which is disposed coaxially with the cavity part, and is provided with at least one air vent port on the annular bottom surface of the cavity part, which is closed by a valve body immediately before injection of the rubber material is completed. It's in the mold.

Hereinafter, embodiments of the present invention will be described based on illustrated examples.

FIG. 7 is a partial cross-sectional view of the molding die of the present invention, which actually has multiple molds.

The cylindrical cavity part 11 is formed by a hollow part of a medium-sized intermediate mold 12 divided into three parts and a cylindrical core part 15 held by a Sensei mold 13. A pot part 17 is formed in the hollow part of the soil mold 16, and the lower end opening of the pot part 1T is
It is narrowed to a smaller diameter than the outer diameter of the core portion 15 and is disposed coaxially with the core portion 15 .

An upper mold 21 having a plunger portion 19 on its lower surface that can be inserted into the pot portion 17 is disposed above the broken underground mold 16.

At this time, between the upper mold 21 and the underground mold 16, a coil spring 22 is installed in a bottomed hole 23 formed in the underground mold 16 in order to prevent the underground mold 16 from lifting up when rubber material is injected. ing.

On the other hand, the Chisei type 1 forming the annular bottom surface of the cavity part 11
3 is provided with an air vent 25, and this air vent 2
A cylinder chamber 26 is formed in a continuous manner below 5, and a piston 28 urged upward by a coil spring 27 is fitted into the cylinder chamber 26. An air vent 25 is provided on the upper surface of the piston 28 to open and close it. A valve body 29 is attached.

Also, first communication holes 31. which communicate the upper and lower spaces defined by the piston 28 and the outside, respectively. A second communication hole 32 is formed in the Chisei mold 13.

Furthermore, an air outlet 33 for releasing the molded product is provided at the upper end of the core part 15 .
5 is closed by the valve body 36 which is urged downward by the coil spring 35 , and the valve body 36 is closed by supplying compressed air from the third communication hole 38 provided in the lower die 37 . is lifted, and the air outlet 33 is opened.

Next, a method of molding a cylindrical molded product using the molding die described above will be explained.

(1) The above-mentioned molding die is set in a molding press, heated at a predetermined temperature, and then the upper mold 21 is raised.

(2) Next, the weighed rubber material M is set in the pot section 17 as shown in FIG.

At this time, the lower end opening of the pot mold 17 is narrowed down.
The rubber material M1B is not placed directly on the core part 15, and the core part 1
It will be in a state where it has risen from 5.

Alternatively, when the rubber material M is approximately the same as the opening diameter of the lower end opening, the bottom of the rubber material M is in contact with the upper end surface of the core portion 15.

(3) In this state, when the upper die 21 is lowered and the rubber material M is compressed by the plunger portion 19, the rubber material M is injected into the cavity portion 11 as shown in FIG.

At this time, since the lower end opening of the pot part 17 is smaller than the diameter of the core part 15 and is arranged coaxially with the core part 15, the height of injection of the rubber material M into the cavity part is adjusted for each circle. The circumferential position is almost the same.

(4) Next, just before the injection is completed, that is, when the injection height of the rubber material M is near the bottom of the cavity part 11,
As shown in FIG. 10, the pressure inside the cavity 11 becomes high, and the valve body 29 descends against the spring force, causing the air vent 25
is opened, and through the cylinder chamber 26 and the first communication hole 31,
The air release force is performed dynamically.

When the air venting is completed, the pressure inside the cavity portion 11 is reduced and the piston 28 is pushed up by the spring force, so the air venting port 25 is closed again by the valve body 29, and the air venting port 2
The rubber material M is prevented from flowing out from 5.

At this time, compressed air is caused to flow into the cylinder chamber 26 below the piston 28 from the second communication hole 32 to ensure the closed state of the valve body 29.

(5) After completing the injection of the rubber material M into the cavity part 11 and vulcanizing it for a predetermined period of time, the upper mold 21. The underground molds 16 are raised separately, and compressed air is introduced through the third communication hole 38.

Then, as shown in FIG. 11, the valve body 36 is lifted up against the spring force, the air outlet 33 is opened, and the two cylindrical molded products are released from the intermediate mold 12.

At this time, compressed air may be fed into the bottom of the molded product 2A from the first communication hole 31 through the air vent 25 in order to facilitate mold release.

Note that another embodiment of the air vent structure is shown in FIG. 12.

A coil spring 4 is installed in a spring chamber 41 in an air vent 39.
2, the valve element 43 is forced upwardly to open and close, but the valve element 43 is normally open and air flows through the first communication hole 4.
4 and is released to the outside.

Immediately before the injection of the rubber material M is completed, the rubber material M presses the convex portion 45 of the valve body 43 and closes the air vent port 39.

At this time, various shapes as shown in FIGS. 13 to 15 are conceivable as the shape of the convex portion.

Since the molding die for a cylindrical rubber molded product of the present invention has the above-described configuration, it produces the following effects.

(a) When molding a cylindrical molded product, the injection height of the rubber material into the cavity part in the circumferential direction is uniform;
No fused portion is formed at the bottom of the cylindrical molded product.

(b) Since the air vent is provided at the annular bottom of the cavity, there is no need to open the mold and vent air from above during injection of the rubber material, and the axial length of the cylindrical molded product can be increased. .

(c) As a result of (a) and (b) above, productivity and yield can be improved when manufacturing seal rings and the like by cutting cylindrical molded products.

[Brief explanation of drawings]

Figure 1 is a sectional view showing an example of a cylindrical rubber molded product using a conventional molding die, Figure 2 is a perspective view of a seal ring obtained by cutting the cylindrical molded product in Figure 1, and Figure 2 is a perspective view of a seal ring obtained by cutting the cylindrical molded product in Figure 1. 3 to 6 are schematic cross-sectional views showing each process using a conventional molding die, FIG. 7 is a partial cross-sectional view of the molding die of the present invention, and FIGS. 8 to 11 are the molding molds shown in FIG. 7. A partial cross-sectional view showing each process using
FIG. 12 is a partial sectional view showing another embodiment of the air vent structure for a molding die according to the present invention, and FIGS.
FIG. 3 is a plan view of an air venting valve body used in the air venting structure shown in FIG. 2; 2.2 people... Cylindrical molded product, 11... Cavity part, 15... Core part, 17... Pot part, 25, 39
...Air vent, 29,43...valve body.

Claims (1)

[Claims] 1. The pot part has a cylindrical cavity part, and the lower end opening of the pot part disposed directly above the cavity part is narrowed to be smaller than the outer diameter of the cylindrical core part forming the cavity part, and
A rubber cylindrical shape having at least one air vent disposed coaxially with the core part and provided on the annular bottom surface of the casing and cavity part with at least one air vent that is closed by a valve body immediately before injection of the rubber material is completed. , molding metal collection for molded products