JPH0526645B2 - - Google Patents

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a mold for forming a mold, and in particular, the present invention relates to a mold for forming a mold, and in particular, the present invention relates to a mold for forming a mold. This invention relates to a ventilation device in a molding die that effectively exhausts gas trapped in the mold.

[Conventional technology and problems]

For example, when molding rubber products using vulcanized rubber, thermoplastic rubber, compression moldable thermoplastic resin, etc., gases such as air are trapped between the molding surface of the molding die and the molded product. If the product is molded without being discharged, small depressions will be formed on the surface of the molded product, resulting in a defective product.

For this reason, various methods have been tried and adopted to remove residual gas, including the provision of numerous small ventilation holes that communicate with the inside and outside of the mold at locations where gas is likely to be trapped in the mold. There is.

However, as the diameter of the ventilation holes increases, while they are effective in removing residual gas, there is a problem in that part of the molded product is extruded through the holes, resulting in the formation of countless small protrusions on the product surface. There is. On the other hand, if the diameter of the ventilation holes is made smaller to prevent part of the molded product from being pushed out through the holes, clogging will occur more easily, which will impede the subsequent exhaust function and result in products with poor appearance. It can be done. Therefore, it is necessary to clean it as needed or periodically to prevent clogging, and the cleaning work requires a great deal of effort. Furthermore, in the case of a structure that cannot be cleaned, it is necessary to replace the mold itself.

[Purpose and structure of the invention]

The present invention is based on the above invention, and includes:
It is an object of the present invention to provide a ventilation device for a molding die that can automatically clean the ventilation holes and has a structure that prevents clogging. Therefore, the ventilation device in the molding die of the present invention is provided in the molding die for discharging the gas trapped between the molding surface of the molding die and the molded product loaded in the molding die. The ventilation device includes a ventilation hole provided on the molding surface of a molding die, a ventilation member fitted into the ventilation hole, and an outer peripheral surface of the ventilation member for discharging the trapped gas to the outside. and an inner peripheral surface of the ventilation hole, and a shape memory alloy having one end connected to a fixed point and the other end connected to the ventilation member, and the shape memory alloy comprising: At the temperature during molding when the molded product is loaded into the molding die, the tip end surface of the ventilation member is held at a position forming a part of the molding surface,
It is characterized in that the shape is memorized so that the tip end surface of the ventilation member is held at a position protruding from or recessed from the molding surface at a temperature during non-molding.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing the configuration of one embodiment of the present invention, and FIG.
4 through 4 are diagrams showing the configuration of other embodiments of the present invention. In the figure, 1 is a molding die, 2 is a ventilation member, 3 is a ventilation member main body, 4 is a shape memory alloy,
5 is a screw part, 6 is a fixed part, 7 is a coil spring, H
and 8 indicate the exhaust section, 9 the collar section, and A the object to be molded, respectively.

In FIG. 1, a ventilation member 2 is inserted into a ventilation hole provided in a molding die 1, and the ventilation member 2 is fixed to the molding die 1 by a fixing portion 6. Ventilation member 2
As shown in the figure, the ventilating member main body 3, a shape memory alloy 4, a threaded portion 5, and a fixing portion 6 are comprised.
Then, one end of the shape memory alloy 4 is connected to the ventilation member main body 3.
The other ends are respectively connected to threaded portions 5, and the threaded portions 5 are screwed into a fixing portion 6 fixed to the molding die 1.

At the temperature during molding when the molding object A is loaded into the molding die 1, the ventilation member main body 3 is placed at a position where the surface of the ventilation member main body 3 forms a part of the molding surface, as shown in FIG. 1a. 3, the shape of the shape memory alloy 4 is memorized so that the shape memory alloy 4 retains the shape of the shape memory alloy 4, and at the non-molding temperature, the ventilation member body 3 is placed in a position protruding from the molding surface, as shown in FIG. 1b. 3, the shape of the shape memory alloy 4 is memorized. In the state during molding shown in FIG. 1a, the mold of the molding die 1 is The gas trapped between the attached surface and the molded object A is discharged. Therefore, in order to exhaust this gas to the outside, the fixed part 6 is provided with an exhaust part H.
If the minute gap G is, for example, about 0.005 to 0.05 mm, sufficient air permeability can be ensured, and its length (depth) L should also be about at least 0.1 to 0.5 mm. Note that the molded surface and the distal end surface of the ventilation member main body 3 can be brought into alignment by adjusting the screw engagement between the threaded portion 5 and the fixing portion 6. Even if a foreign object gets caught in the minute gap G during molding and is likely to cause clogging, after molding, the ventilation member main body 3 will temporarily retreat to the retracted position as shown in FIG. 1b. Therefore, when the mold is restored to the state shown in FIG. 1A during molding, the foreign matter has already been removed and clogging can be eliminated.

The second embodiment shows another embodiment of the present invention in which the memory shape of the shape memory alloy 4 is reversed from that shown in FIG.
It is a diagram. In the example shown in FIG. 2, the shape memory alloy 4 memorizes a curved shape at the temperature during forming,
At non-molding temperatures, it retains a straight shape. Therefore, when not molded, Fig. 2b
As shown in FIG. 2, the ventilation member main body 3 comes to protrude from the molding surface of the molding die 1.

Furthermore, FIG. 3 shows another embodiment of the present invention in which the shape memory alloy 4 memorizes its shape in a coil shape and holds the ventilation member main body 3 in an equilibrium state with the coil spring 7. FIG. 3a shows the state during molding, and FIG. 3b shows the state when not molded. In FIG. 3, the ventilation member main body 3 has a flange 9, and a coil is inserted between one surface of the flange 9 and a fixing part 6 screwed onto the outside of the molding die 1.
A spring 7 is fixed, and a coil-shaped shape memory alloy 4 is fixed between the other surface of the flange 9 and the molding surface side of the molding die 1. The coil spring 7 compresses the shape memory alloy 4 when the shape memory alloy 4 is cooled, that is, when it is not shaped as shown in FIG. 3b.
The strength should be about 1/3 to 1/5 of the strength of the alloy. As mentioned above, the fixing part 6 is attached to the molding die 1.
The coil spring 7 is screwed into the ventilation hole of the coil spring 7 to fix one end of the coil spring 7, and has an exhaust part 8. Exhaust part 8
is capable of discharging the gas discharged from the molding surface to the outside through a minute gap between the outer peripheral surface of the ventilation member main body 3 and the inner peripheral surface of the ventilation hole of the molding die 1, and also allows screwing adjustment. It has a box-like depression. This screw adjustment allows the molding surface of the molding die 1 and the surface of the tip of the ventilation member main body 3 to be brought into alignment as shown in FIG. 3a.

FIG. 4 shows another embodiment of the present invention in which the arrangement of the coiled shape memory alloy 4 and the coil spring 7 is reversed from that shown in FIG. 3. In the example shown in FIG. 4, the arrangement of the shape memory alloy 4 is opposite to that in the example shown in FIG. Since the alloy 4 is compressed and draws the ventilation member main body 3 towards the back, its tip is also held at a position drawn towards the back from the molding surface of the molding die 1. Also,
In both the example shown in FIG. 3 and the example shown in FIG. 4, the shape memory alloy 4 is in a compressed state by the coil spring 7 when not being formed. Of course, the alloy 4 can be configured to be compressed by the coil spring 7. In the embodiments shown in FIGS. 3 and 4, since the coil spring 7 is provided, the coiled shape memory alloy 4 has complete reversibility due to temperature rises and falls. It doesn't have to be.

Generally, during vulcanization molding of rubber products, the temperature is as high as 150°C to 180°C. Therefore, if normal temperature is the temperature when not molded, there is a temperature difference between when molded and when not molded. Therefore, although not shown in FIGS. 1 to 4, an air supply path from the outside is provided in the room where the shape memory alloy 4 is located in the ventilation hole of the molding die 1 so that it can be cooled, or It goes without saying that the state may be rapidly changed from the molding state to the non-molding state by supplying air from the exhaust portions H and 8 for cooling. By promoting the state change in this way, the cleaning effect of micro gaps can be improved.

Note that it goes without saying that the shape of the ventilation hole on the molding surface of the molding die and the cross-sectional shape of the tip of the ventilation member body can be various shapes such as circular, elliptical, polygonal, etc.
The present invention does not change in any way even if the shape is different.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, a ventilation member is inserted into the ventilation hole of a molding die, and gas is discharged through the minute gap, and the ventilation member is inserted into the ventilation hole of a mold for molding, and the ventilation member is used both during molding and when not molding. Since the piston moves according to the memorized shape of the shape memory alloy, it is possible to automatically clean minute gaps and prevent clogging. Further, it is possible to set a minute gap so that small protrusions do not occur in the product, and it is possible to improve the quality of the product.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of one embodiment of the present invention, and FIG.
4 through 4 are diagrams showing the configuration of other embodiments of the present invention. 1... Molding mold, 2... Ventilation member, 3... Ventilation member main body, 4... Shape memory alloy, 5... Threaded part, 6... Fixing part, 7... Coil spring, H and 8... Exhaust part, 9... Tsuba Part, A...molding object.

Claims (1)

[Claims] 1. A ventilation device in a molding mold that discharges gas trapped between the molding surface of the molding mold and the molded product loaded in the molding mold,
A ventilation hole provided on the molding surface of the molding die, a ventilation member fitted into the ventilation hole, and an outer circumferential surface of the ventilation member and the inside of the ventilation hole for discharging the trapped gas to the outside. The shape memory alloy is provided with a minute gap formed between the mold and the peripheral surface, and a shape memory alloy whose one end is connected to the fixing point and the other end is connected to the ventilation member, and the shape memory alloy is placed in the mold for molding. At the temperature during molding when a molded product is loaded, the tip end surface of the ventilation member is held at a position forming a part of the molding surface, and at the temperature during non-molding, the end surface of the ventilation member forms a part of the molding surface. 1. A ventilation device for a molding die, characterized in that the shape is memorized so as to be held in a more protruding or retracted position.