JPH03281310A - Mold - Google Patents

Abstract

PURPOSE:To sufficiently pack a molding material even into the thin-walled parts of a mold by providing pin insertion ports on the mold and inserting a plurality of pins into the pin insertion ports to set them thereto. CONSTITUTION:When a top force 10 and a bottom force 12 are registered via an intermediate mold 20 and then a rubber material is injected into each cavity through an injection port 42 under the registered condition, cylindrical thick- walled molding parts 38 having a low flow resistance are first filled with the rubber material and, thereafter, the rubber material infiltrates into disk-like thin-walled molding parts 40 from their peripheral portions. Accordingly, air is eventually forced into the thin-walled molding parts 40 by the rubber material; however, the air is discharged to the external side through the gaps 68, 70 of degassing pin mechanisms 54 and through vent ports 52 formed in the bottom force 12. As a result, the thin-walled molding parts 40 are not made thinner in thickness, and a failure in the adhesion of the rubber material with metal fittings 28 is not caused.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a mold, and more particularly to a technical means for releasing air inside a cavity.

(Prior art and inventions try to solve! Im) 4th
As shown in the figure, when a rubber molded product lot having a thin wall portion 100 is molded by injecting rubber material into the cavity 104 of the mold 102, the rubber material is injected into the cavity 104 from the injection port 105. first fills the part for forming the thick part, and then finally goes around to the part for forming the thin part 100 and fills the entire cavity. Since the flow resistance of the rubber material is large in the part for forming the thin-walled part, the rubber material flows into this part last.

However, when the rubber material finally goes around to the part for forming the thin-walled part, the air that was present in the cavity from the beginning and the scum (hereinafter simply referred to as air) generated due to the heating of the rubber material are If the rubber material is not fully wrapped around the thin-walled part and the rubber material is not fully wrapped around the thin-walled part, or in the case of a rubber molded product with a metal fitting 106, air may be trapped at the interface with the metal fitting 106. This causes poor adhesion between the rubber and the metal, causing the thin wall portion 100 to bulge when the molded product is removed.

A common means to prevent this is to provide a hole 108 that communicates with the thin-walled part 100 in the cavity as shown in the figure above, so that when the rubber material is injected, the air inside the cavity is pumped out together with the rubber material. It is intended to make A.

However, if this is done, the sigma rubber material escapes into the hole 108, causing a break 110. Therefore, in this case, a step of cutting out the number 110 is required after molding. However, as shown in Figure t, if the lip 110 extends beyond the depth of the product (i.e. extends beyond the bottom of the hole), it is difficult to remove the beak 110, especially when automating product molding. This becomes a major obstacle, resulting in FWIN that is difficult to automate.

Even when removing the paris 110 manually, it is difficult to remove the pari 110 cleanly from the root, and a protrusion remains after the pari 110 is removed. It also causes deterioration of characteristics.

Means for Solving Problem 1) The mold of the present invention has been devised to solve the problem H, and its gist is to mold a molded product having a thin wall part by introducing molding material into the cavity. In a mold for molding by injection, a pin insertion port is provided in a state that communicates the thin-walled portion molding portion of the cavity with the outside, and the entire cross section of each pin is combined to form a cross section of the same shape as the pin insertion port. A plurality of pins to be formed are inserted into the pin insertion openings, and air inside the cavity is allowed to escape to the outside through minute gaps between the pins when the molding material is injected.

(Operation and Effects of the Invention) As described above, the present invention prevents air from escaping together with the molding material through the holes provided in the mold, and instead provides a pin insertion hole in the mold and inserts a plurality of pins into the hole.・I made it possible to do it. Here, the plurality of pins may be combined by fitting their inner and outer peripheral surfaces to each other, or in some cases, three pins may be combined.
It is also possible to combine pins such as split pins and quarter split pins so that the split surfaces meet, and the number of pins can be set to an appropriate number such as two or three.

When molding material is injected into the cavity with multiple pins combined and set in the pin insertion slot, when the molding material finally comes around to the thin-walled part, the air forced into the pins and It can escape to the outside through a small gap with the pin. For this reason, the inconvenience of preventing trapped air from entering the molding material occurs, and the molding material can be sufficiently filled up to the thin wall portion.

Since the gap between the pins is minute, the molding material will not leak out through this gap, and no deburring operation is required after molding. Therefore, according to the present invention, it becomes easy to automate the molding process of a molded article.

Further, since no flash is generated, there is no problem that the flash or the protrusions remaining after removing the flash impair the properties and appearance of the molded product.

(Example) Next, an example in which the present invention is applied to a mold for molding a rubber product will be described in detail based on the drawings.

In FIG. 1, reference numerals 10 and 12 denote an upper mold and a lower mold, which constitute the main body of the mold of this example, and are provided with recesses 16 and 18 of a predetermined depth on opposing surfaces, respectively. Place 16
, 1g are fitted into the medium mold 2o so that the molds are mutually matched.

Here, the middle mold 20 is made up of a plurality of split molds, which are fitted into the recess 18 of the lower mold 12 and integrated. In the integrated state, a plurality of cavity forming holes 22 are formed that penetrate vertically as shown in the figure. Further, in the intermediate mold 20, in the integrated state, an annular step portion 24 is formed at the upper end of each cavity forming hole 22, and with respect to the step portion 24, a predetermined height is formed at the center of the lower surface. Sa no protrusion 2
Metal fittings 28 each having a number 6 are fitted therein. Note that this metal fitting 28 is for integrally fixing the molded product.

On the other hand, on the bottom surface of the recess 18 of the lower part 512 into which the middle mold 20 is fitted, there are a plurality of recesses with a larger diameter than the cavity forming holes 22 so as to be concentric with each cavity forming hole 22 formed by the middle mold 20. A location 30 is formed.

Then, for each recess 30 of these lower molds 12, a core mold 32
are arranged respectively.

This core mold 32 consists of a flat plate part 34 having a shape corresponding to the recess 30 of the lower mold 12, and a protrusion part 36 of a predetermined height that stands upright at the center of the flat plate part 34. The protrusion 36 is fitted into the recess 30 of the lower mold 12 in the flat plate portion 34 so as to protrude concentrically into the cavity forming hole 22 of the middle mold 20 . In this example, this allows the φ mold 20 to be
In each of the cavity forming holes 22, a cavity is formed, each consisting of a cylindrical thick-walled molded part 38 and a disc-shaped thin-walled molded part 40.

In addition, there is an injection port 4 for injecting the rubber material into each cavity.
2 is formed so as to pass through the upper mold lO and the middle mold 20 when the upper mold 10 and the lower mold 12 are assembled, and is opened into the thick molded part 38 of the cavity. Here, an annular groove 44 is formed on the upper surface of each core mold 32 so as to surround the protrusion 36, and an annular metal fitting 46 that is integrally fixed to the molded product is disposed within this groove 44. It has become.

By the way, each core mold 32 has a flat plate part 34 and a projection part 36.
A through hole 48 is formed vertically through the cavity to face the thin molded part 40 of the cavity. One core mold 3
The portion of the lower mold 12 where the through hole 48 of No. 2 opens is provided with the through hole 4
A bottomed hole 50 having a diameter larger than 8 is formed, and
A through hole 52 is formed to communicate the bottomed hole 50 with the outside. Here, a degassing pin mechanism 54 is disposed to be accommodated in a bottomed hole 50 formed in the lower mold 12 and a through hole 48 formed in the core mold 32.

As shown in FIG. 2, this degassing pin mechanism 54 includes an outer sleeve 56, an inner sleeve 58 fitted into the outer sleeve 56, and a central sleeve fitted into the inner sleeve 58. pin 60, and the outer sleeve 56, as shown in FIG. The outer sleeve 56. With the end surfaces of the inner cylinder sleeve 58 and the center pin 60 flush with each other, and with the end surfaces flush with the thin molded part 40 of the cavity,
The outer sleeve 56 is fitted into the through hole 48 of No. 2 and assembled. Here, in the fitted state of the gas vent pin mechanism 54, the outer sleeve 56 and the inner sleeve 5 that constitute the gas vent pin mechanism 54 are shown.
8 and between the inner cylinder sleeve 58 and the central pin 60, as shown in Figure Ps3, it is small enough to prevent the intrusion of rubber material and allows the flow of gas such as air. The gap 68.70 which is large enough for the degree of
The cavity is communicated with the outside space through the through hole 52 of the lower mold 12. The gaps 68 and 70 as described above are formed by setting the inner and outer diameters of the outer sleeve 56, the inner sleeve 58, and the central pin 60, and the unevenness of their fitting surfaces.

In a mold having such a structure, an upper mold 10 and a lower mold 12
When the molds are molded together through the medium mold 20 and a rubber material is injected into each cavity through the injection port 42 in the mold-matched state, the rubber material first gives priority to the cylindrical thick-walled molded part 38 with low flow resistance. After filling the thick molded part 38,
It comes to wrap around into the disc-shaped thin-walled molded part 40 from its peripheral part. Therefore, the air is finally forced into this thin-walled molded part 40 by the rubber material, but the air driven into this thin-walled molded part 40 enters the gap 68, 70 of the scrap removal pin mechanism 54 and the lower die 12. Through hole 5 formed
Since the air is discharged to the outside through the thin-walled molded portion 40, the air is not trapped in the thin-walled molded portion 40. Therefore, the air trapped in the thin-walled molded portion 40 causes a lack of thickness in the thin-walled molded portion 1s40. There is no possibility that the air will be generated or the air will enter the interface with the metal fitting 28, resulting in poor adhesion between the rubber material and the metal fitting 28.

Moreover, since the gaps 1168 and 70 of the gas venting pin mechanism 54 are set sufficiently narrow to not allow rubber material to enter, there is no possibility that rubber material will enter the gaps 68 and 70 and cause paris. Therefore, there is no need for deburring work, and the properties and appearance of the molded product are not impaired by any protrusions remaining after the deburring is removed.

The embodiments of the present invention have been described in detail above, but one Ji! The invention can also be implemented in other ways.

For example, in the above embodiment, the gas vent pin mechanism 54 is connected to the outer sleeve 56. 3 of the inner cylinder sleeve 58 and the central pin 60
Although it was considered to be a fitting structure of members, it is also possible to configure a gas venting pin mechanism with a fitting structure of a central pin and one or three or more cylindrical members, and it is also possible to configure a degassing pin mechanism by combining the central pin and one or more cylindrical members. It is also possible to configure the degassing pin mechanism with a plurality of split pins.

Furthermore, in the above embodiment, the thin-walled molded portion 40 was formed between the metal fitting 28 that is integrally fixed to the molded product and the mold (φ child mold 32), but the thin-walled molded portion is It is also possible to apply the present invention to a type of mold formed between molds, and in some cases, a gas venting pin mechanism may be provided by penetrating a metal fitting that is integrally fixed to the molded product. is also possible.

Other 1 The present invention can be implemented with various modifications based on the knowledge of those skilled in the art without departing from the spirit thereof.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a mold assembly showing an example of the mold according to the present invention, FIG. FIG. 2 is an explanatory diagram showing a cross section of the gas venting pin mechanism together with an enlarged view of two parts thereof. @Figure 4 is a diagram corresponding to Figure 1 of a conventional mold. lO: Saturn 20: Medium 28: Metal fittings 38: Thick molded parts 48, 52: Through hole 56: Outer cylinder sleeve 60: Center pin 12: Lower mold 22: Cavity forming hole 32: Core mold 40: Thin molded part 54 : Gas vent pin mechanism 58 : Inner cylinder sleeve 68 , 70 : Gap

Claims (1)

[Claims] In a mold for molding a molded product having a thin-walled part by injecting a molding material into a cavity, a pin insertion opening is provided in a state that communicates the part of the cavity for molding the thin-walled part with the outside, and the entire cross-section of each pin is A plurality of pins, which together form a cross section of the same shape as the pin insertion hole, are inserted into the pin insertion hole, and when the molding material is injected, the air inside the cavity is vented to the outside through a small gap between the pins. A mold that is characterized by being designed to allow air to escape.