JPH03338Y2 - - Google Patents

Description

[Detailed description of the invention] Industrial field of application This invention relates to a gas venting structure for a mold for foam molding.

2. Description of the Related Art A conventional gas vent structure for a mold for foam molding includes, for example, a gas vent structure for a foam urethane handle mold shown in FIGS. 6 to 7. That is, the material injected from the lower gate 42 of the mold 41 gradually rises while foaming, and while being pushed up by the material, the gas in the mold cavity 43 is released from the gas vent 44 at the top of the mold. Although,
In this conventional mold gas venting structure, the gas venting portion 44
It is not only possible to make the cross-sectional area of the gas vent part 44 very large, but also because the degassing portion 44 can only be provided locally, which not only has the disadvantage of not being able to avoid the generation of voids due to incomplete degassing. Since the gas venting part 44 is open to atmospheric pressure, the synthetic resin is low near the gas venting part 44 in the upper part of the mold 1, resulting in low density and low hardness, whereas in the lower part of the mold. Since the synthetic resin pressure is high, resulting in high density and high hardness, there is a drawback that there is a considerable difference in density and hardness between the upper and lower parts of the handle.

Problems that the invention aims to solve This invention solves these drawbacks of the gas vent structure of conventional foam molding molds, makes it difficult for differences in density and hardness to occur in molded products, and eliminates voids in molded products. The purpose is to reduce the occurrence of such occurrences.

Means for Solving the Problems The degassing structure of the foam molding mold of this invention is one in which two or more sets of degassing unit structures in which a slit and a cavity are communicated are arranged in series.

Next, examples of the degassing structure of the foam molding mold of this invention will be described with reference to the drawings.

Embodiment 1 As shown in FIGS. 1 and 2, the gas venting section 2 of the mold 1 consists of two opposing blocks 3', 3''. One block 3' has three recesses 4. The other block 3'' is provided with three protrusions 5 so as to enter the recesses 4 of one block 3'.

One block 3' is removably attached to one mold plate 1', and the other block 3'' is removably attached to the other mold plate 1'', so that when the mold 1 is closed, the This is a gas venting part 2 of a mold 1 in which three slits 8 and three cavities 9 are alternately formed.

In the gas venting structure of the foam molding mold of Example 1, when material is injected from the lower gate 10 of the mold 1, the material gradually rises while foaming, and is pushed up by the material to fill the mold cavity. The gas in 11 is compressed by the slit 8 from the gas venting part 2 at the top, and expanded by the cavity 9, and as this compression and expansion are repeated sequentially, the pressure is gradually reduced. The synthetic resin pressure of the material will not drop suddenly, making it difficult for differences in density and hardness to occur in the molded product molded with the mold 1, and reducing the occurrence of voids in the molded product. .

Embodiment 2 As shown in FIG. 3, the gas venting section 22 of the mold 21 consists of two blocks 23', 23'' facing each other. This is a gas venting part 22 of a mold 21 which is provided with sharp protrusions 24 and 25, and six slits 28 and six cavities 29 are formed alternately.

In the gas venting structure of the foam molding mold of Example 2, the slit 28 is twice as large as that of Example 1.
and the cavity 29, the number of repetitions of compression and expansion of the gas in the mold cavity is doubled, and the pressure drop becomes slower.

Embodiment 3 As shown in FIGS. 4 and 5, the gas venting section 32 of the mold 31 is formed by two opposing blocks 33',
33''. Three recesses 34 are provided in one block 33', and the bottom surfaces of the recesses 34 are inclined.

This one block 33' is attached to the mold plate 3.
One block 33' is provided on an end frame 36 which is inserted into the sliding path 35 of the block 1' and fixed by bolting to the mold piece 31' so as to be slidable up and down with a center bolt 37.

Three protrusions 38 are provided in the other block 33'' so as to fit into the recess 34 of one block 33', so that three slits 39 and three cavities 40 are alternately formed. This is the gas venting part 32 of the mold 31 which is curved.

In the gas venting structure of the foam molding mold of Example 3, one block 33' is moved from the mold piece 3 by rotating the center bolt 37 in the forward and reverse directions.
1' sliding path 35 up and down, one block 3
Since the bottom surface of the recess 34 provided at the block 3' is inclined, the size of the slit formed by the bottom surface of the recess 34 and the protrusion 38 of the other block 33'' can be adjusted to be larger or smaller. Therefore, the optimal gas venting structure can be set at any time for the shape and size of the molded product to be manufactured.

Effects of the invention The degassing structure of the mold for foam molding of this invention has two or more sets of degassing unit structures in which the slit and the cavity communicate with each other, arranged in series, so that compression by the slit and expansion by the cavity are performed sequentially. Repeated gas vent passages are formed, and even if the cross-sectional area of the gas vent opening into the mold cavity is made large, the synthetic resin pressure near the gas vent area will not drop suddenly, and the density difference in the molded product will be reduced. This has the effect that density differences are less likely to occur, and the occurrence of voids in molded products can be reduced.

[Brief explanation of the drawing]

Fig. 1 is a front view of one embodiment of the product of the present invention, Fig. 2 is an enlarged sectional view taken along line A-A of Fig. 1, Fig. 3 is an enlarged sectional view of another embodiment of the product of the present invention, and Fig. 4 is an enlarged sectional view of yet another embodiment of the product of the present invention, FIG. 5 is an enlarged perspective view of the same before assembly, and FIG. 6 is a front view of the conventional product.
FIG. 7 is an enlarged sectional view taken along the line BB in FIG. 6. 1 is a mold, 2 is a gas venting part, 8 is a slit, 9
is the hollow part.

Claims (1)

[Scope of utility model registration request] A degassing structure for a mold for foam molding, characterized in that two or more sets of degassing unit structures in which a slit and a cavity are communicated are arranged in series.