JPS633796Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a vulcanization mold for molding foamed rubber or crosslinked synthetic resin foam.

Conventionally, when producing foamed rubber or crosslinked synthetic resin foam, a mold that is divided into upper and lower halves is usually used. That is, in a compression molding press that has a lower mold filled with a predetermined compound and an upper mold that is a smooth thin iron plate with a plated surface and is fixed to a hot platen in the upper part of the press, the filling is The material is heated under pressure, and after a certain period of time, the ram of the press is lowered to open the hot platen to form a molded product. At that time, the foam filled in the mold was
The foam expands all at once due to the expansion pressure of the foaming agent in the compound, and the foam suddenly pops out of the mold. Therefore, in order to make it easier for the foam to pop out, the lower mold cavity is usually provided with a taper that opens at an angle of 45 to 60 degrees with respect to the upper opening. For high foam materials with a density of about 0.15 to 0.10 g/ ^cm3 ,
It is said that it is safer to set the taper angle of the lower mold to 60° because the force when the product is ejected from the mold is large and can easily cause problems such as tearing around the foam molded product.

By the way, the density of foam varies depending on the type and amount of blowing agent added to the compound, but the density
For low- and medium-sized foams of 0.5 g/cm ³ or more, the expansion pressure that pushes them out of the mold is weak, so it is rare for the upper and lower molds to stick to the molded product and prevent it from separating from the hot platen of the press machine. It only occurs in density
If the foam is less than 0.5g/ ^cm3 , the expansion pressure will be high and the foam will expand rapidly when the heat plate of the press is opened. There is a problem in that a vacuum is generated between the two and the foamed molded product and the lower mold are attracted to the upper mold attached to the upper heating platen. After about 20 seconds, when the degree of vacuum decreases, the molded foam product and the lower mold fall onto the lower heating platen. Therefore, the work is dangerous, the work is interrupted, and it may cause damage to equipment such as molds and presses, which may also affect costs. In addition, the foam molded product that has fallen will have traces of sticking and cavities in the center, and when the heating plate is opened, the expansion will be uneven, causing the molded product to deform and become uneven in thickness. The disadvantage was that it was not possible to obtain a suitable product.

Based on these facts, the present invention has been developed so that when the lower heating platen of the press machine descends, the lower mold and the foamed molded product follow the lower heated platen, and the molded product foams uniformly, preventing deformation and thickness. It is an object of the present invention to provide a mold that has no non-uniformity, no damage to equipment such as a mold and a press machine, and has operational safety. The gist of the present invention to achieve this purpose is to provide at least one small circular hole for air introduction in the lower mold cavity part, preferably in the corner part, during mold vulcanization using a compression molding press. The mold for molding a foam is characterized in that a piece is inserted into the hole, and an air introduction groove connected to the small hole is provided on the back side of the lower mold.

The embodiments shown in the drawings will be described below.

1 to 4 show conventional molds for vulcanizing foam. The compound is filled into the cavity 3 of the lower mold 2 in Fig. 1, heated under pressure in the state shown in Fig. 2, and after a certain period of time, when the heating plate is opened, the compound 7 expands and completes the foam molding. However, at this time, as shown in FIG. 3, the parts A and B become vacuum, and the foamed molded product 8 and the lower mold 2 are attracted to the upper mold 1. After about 20 seconds, when the degree of vacuum in parts A and B decreases, the foamed molded product 8 appears as shown in Figure 4.
As described above, the lower mold 2 falls onto the lower heating plate 6.

5 to 7 show an embodiment of a mold for curing foam according to the present invention. In the example shown in FIG. 5, the corner portion 4 of the cavity 3 of the lower mold 2 is
There are small circular holes 9 in the two corners of the mold on the side where the handle 4 is attached, through which the operator takes in and out the mold, fills the unvulcanized rubber compound, and takes out the product. is provided through the mold. Note that if the lower side of the small hole is counterbore into a dish shape, the air suction effect will be even more remarkable. In order to make the thickness of the product uniform, the cavity 3 of the lower mold is provided with a crown 12 so that the center of the cavity is at its highest point, as shown in FIG. The circular small hole 9 has a recess 13 on the side of the cavity 3 so that the head of the top 10 can fit therein. In addition, the circular small hole 9
The hole position is slightly shifted outward from the corner part so as not to interfere with the product, and in order to introduce air from the outside, an air hole is connected to the small hole and placed on the back side of the lower mold. An introduction groove 11 is provided. The grooves 11 may be provided at two locations as shown in FIG. 5, or may be provided at one location. Further, instead of the groove on the back side of the mold, for example, a round hole may be formed from the side of the mold and connected to the small hole 9. An iron piece 10 is inserted into this small air introduction hole 9.

For example, when a mold cavity 3 is filled with an unvulcanized rubber compound 7 to which a foaming agent has been added and vulcanized under pressure in a press, the rubber compound in the cavity is heated and pressurized into the mold. It flows all over the inner surface and presses against the head of the piece, acting as a seal to prevent the rubber and gas generated from leaking. This piece is strongly pressed against the surface of the lower mold by the gas pressure caused by the compound and foaming agent in the cavity when the rubber is vulcanized.

When the ram of the press machine is lowered, a vacuum is created in the cavity 3 when the foamed molded product 8 is ejected to the outside due to the expansion pressure, but the piece floats up or pops out of the small hole, and the small hole 9 for air introduction is created. The air introduction groove 11 connected thereto sucks in outside air and rapidly sucks the air into the cavity 3. For this reason, in a normal mold, the cavity 3, which should be in a vacuum,
Since the mold is filled with air, adhesion between the lower mold 2 and the molded product 8 does not occur. Furthermore, a vacuum is not generated between the upper mold 1 and the molded product 8, which are fixed to the hot platen 5 by bolts, because the vacuum caused by the introduction of air into the lower mold 2 is not generated. There should be no adsorption between it and the molded product 8. In this embodiment, depending on the work conditions, rubber flows between the mold recess 13 and the cylindrical head of the piece 10 during pressure vulcanization, causing the molded product 8 to fly out of the mold. In rare cases, the rubber that had flowed in during the process interfered with the ejection of the pieces, and air introduction did not go well. In order to completely eliminate the drawback of rubber flowing in,
In the example shown in Figure 7, the head of the piece is shaped like an umbrella.
4, the surface of the circular small hole part is a smooth surface, and the boundary between the small hole part 9 and the crown 12 is slightly stepped. According to this example, the umbrella-shaped part 1 of the top
Since the back surface 15 of 4 is an extremely smooth polished surface,
When vulcanizing under pressure with a press machine, when the mixture is pressed against the surface of the small hole in the lower mold by the flowing compound and gas pressure, the gap disappears, and there is almost no inflow of rubber into this area. is obtained. Therefore, the phenomenon that the piece 10 and the lower mold 2 are in close contact with the inflowing rubber and the piece 10 does not move and air does not flow in does not occur, and as shown in Fig. 9, when the hot platen is opened, molding is performed extremely smoothly. The product 8 is separated into the lower mold 2 and the upper mold 1.

Furthermore, as shown in FIG. 8, if a V-shaped notch is provided in at least one, preferably two places on the foot of the piece 10, the piece will float slightly just before the molded product 8 pops out of the mold. When hit, it has the effect of sucking in air, and this effect is more pronounced than that of a piece without a notch.

As described above, by using the vulcanization mold of the present invention, the molded product can be ejected out of the mold extremely smoothly by the lowering of the ram of the press, and the gap between the molded product and the upper and lower molds is There will be no vacuum part,
The molded product and the upper and lower molds separate without any abnormality, there is no danger of the lower mold falling, and problems such as uneven thickness of the molded product, deformation, and traces of mold cavities are completely eliminated. I was able to resolve it.

[Brief explanation of drawings]

FIG. 1A is a sectional view of a conventional lower mold, and FIG. 1B is a plan view of the same. Figure 2 is a cross-sectional view of a mold during pressure vulcanization between the heating plates of a conventional press machine, and Figure 3 is a sectional view of a mold during pressure vulcanization between the hot discs of a conventional press machine, and Figure 3 shows a conventional mold in which the upper and lower molds and the molded product are attracted by vacuum action during the initial stage of ram processing. The sectional view shown in FIG. 4 is a sectional view showing a state in which a conventional mold and a molded product are dropped onto a hot platen. FIGS. 5A and 5B are a plan view and a sectional view of a lower mold showing an embodiment of the vulcanization mold according to the present invention. FIG. 6 is a partially enlarged view showing the lower mold part and the state of insertion of the piece, showing one embodiment of the present invention. FIG. 7 is a partially enlarged view of the piece with an umbrella-shaped head and the lower mold. Figures 8A and 8B are a side view and a plan view from the foot of a top with an umbrella-shaped head and two V-shaped notches in the foot. Figure 9 shows the vulcanization mold of this invention when the hot platen is opened.
FIG. 3 is a sectional view showing a state in which the molded product and the lower mold are smoothly separated from the upper mold. 1: Upper mold, 2: Lower mold, 3: Cavity,
4: Handle, 5: Press machine upper heating plate, 6: Press machine lower heating plate, 7: Unvulcanized rubber compound, 8: Foamed molded product, 9: Small hole for air introduction, 10: Top, 11: Air Introduction groove, 12: Lower mold crown part, 13: Concave part, 14: Umbrella-shaped part of piece, 15: Back surface, 16:
V-shaped notch, A, B: vacuum part.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) In mold vulcanization of foam using a compression molding press machine, a small hole for air introduction is provided in at least one place in the lower mold cavity, and a frame is formed in the hole. 1. A vulcanization mold for molding a foam, characterized in that a hole is inserted into the mold, and an air introduction groove connected to the hole is provided on the back side of the lower mold. (2) The vulcanization mold for foam molding according to claim (1) of the utility model registration claim, wherein the top of the top is umbrella-shaped. (3) The vulcanization mold for foam molding according to claim (1), wherein the top has at least one V-shaped notch in its foot. (4) The vulcanization mold for foam molding as set forth in claim (1) of the utility model registration claim, characterized in that the small air introduction holes are located at the corners of the lower mold cavity.