JPH0156898B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to foam molding of a foamable thermoplastic synthetic resin,
Especially in so-called transfer type foam molding equipment,
This invention relates to the structure of a molding die for ensuring reliable transfer of a molded article from a heating mold to a cooling mold.

Foam molded products made from foamable thermoplastic synthetic resins such as foamed polystyrene, foamed polyethylene, and rigid foamed polyurethane are widely used for their properties such as excellent heat retention, cushioning effect, chemical stability, toughness, and low apparent specific gravity. It is widely used as packaging material for foodstuffs, machinery and equipment, etc. Such molded bodies are usually made by filling pre-foamed thermoplastic synthetic resin particles into a mold consisting of a male mold and a female mold that can be opened and closed and fit together to form a mold cavity. death,
Manufactured by heating the mold to further foam and plasticize the resin particles to fuse and integrate them with each other, then cool the mold to harden and stabilize the resin, open the mold, and take out the molded product. It had been.

However, using the same mold to complete the process cycle of filling raw resin, heating, foam molding, cooling, and taking out results in a large loss of thermal energy and time, reduces work efficiency, and In order to solve the problem of increased manufacturing costs, a so-called transfer molding method has recently been proposed and is being used in commercial production.

The transfer molding method uses a heating mold that is constantly heated and a cooling mold that is constantly kept cool.The heating mold is filled with raw resin particles, foam molding is performed, and the particles are plasticized and fused. Then, one mold of the heating mold, for example, the female mold, is moved while supporting the molded semi-finished product and fitted with the male mold of the cooling mold, and the semi-finished product is turned into a cooling mold. In this method, the cooling male mold that has received the semi-finished product is fitted with the cooling female mold to cool, solidify and stabilize the semi-finished product to obtain a product. With this method, there is no need to repeat heating and cooling for the same mold, so thermal energy is significantly saved, process cycle time is significantly shortened, and molding operations can be performed one after another, increasing productivity. It has the advantage of being greatly improved.

In this molding method, as a means of transferring the semi-finished product from the heating moving mold to the cooling fixed mold, compressed air is usually jetted from the heating steam hole of the moving mold to apply force to push the semi-finished product toward the exit of the moving mold. ,
In the cooling fixed type, vacuum suction is applied to attach the semi-finished product to the mold. In this state, when the heating transfer mold is moved back, the semi-finished product remains in the cooling fixed mold, and the transfer is completed. However, depending on the shape of the semi-finished product, a transfer error may occur, and the semi-finished product may be taken home while remaining in the heating transfer mold, or it may separate from both molds and fall. The reason for this is that when the heating movable mold and the cooling fixed mold are fitted together and the movable mold is further retracted, the semi-finished product remains in the mold that has greater mold release resistance between the mold and the semi-finished product. In order to ensure that the air remains in the cooling fixed mold, the above-mentioned blow and air intake actions are performed, but depending on the shape, the mold release resistance from the cooling fixed mold may be relatively small, or compressed air may leak or There are cases where vacuum leaks are likely to occur, and transfer errors are likely to occur at such times.

The present invention was made to solve the above-mentioned problems in the transfer molding method, and its purpose is to reliably transfer semi-finished products from the heating transfer molding to the cooling fixed molding, The purpose is to increase work efficiency and improve product yield.

The apparatus of the present invention for achieving the above-mentioned object consists of two sets of molding molds each having a pair of male and female molds that can be opened and closed with each other to form a mold cavity. The second mold is a heating mold equipped with a supply port for the expandable thermoplastic resin particles into the mold cavity and a means for heating the inside of the mold cavity, and the second mold is a means for cooling the molded article in the mold cavity. and a means for releasing the mold, and furthermore, the male mold of one mold and the female mold of the other mold are fitted into each other by the movement of either one, and the mold is supported by the heating mold. In a transfer type molding device configured to transfer the molded product into a cooling mold, a mold is placed at an appropriate location on the surface of the cooling mold that receives the molded product in contact with the molded product, parallel to the opening/closing movement axis of the mold. A mold for foam molding characterized in that a pin having a shaft is installed to increase the resistance to releasing the molded product from the cooling mold.

Embodiments of the apparatus of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a schematic vertical cross-sectional view showing one example of the device of the present invention, and FIGS. 2 to 4 are explanatory diagrams showing the order of its operation.

In FIG. 1, a first molding die, that is, a heating die 1, and a second forming die, that is, a cooling die 2, each have a pair of male dies 1a, 2a and female dies 1b, 2b. The mold and the female mold are configured to be openable and closable with respect to each other, and mold cavities 3 and 4 can be formed by closing the molds. The opening and closing of such a mold is done by using one mold, for example, in the examples shown in FIGS. 1 to 4, female molds 1b and 2 are used.
This is carried out by using movable mold b and moving it backward and forward in the central axis direction with respect to fixed molds 1a and 2a. That is, the opening/closing movement axis coincides with the central axis. Each mold has behind it a mantle 6, 7, 8, 9 surrounded by a mold frame 5. mantle-shaped part 6 of heating mold 1;
A heating medium such as heated steam is fed into the mold cavity 7 from heating medium supply ports 10 and 11, heats the mold cavity 3, and is discharged from heating medium discharge ports 12 and 13. On the other hand, a cooling medium such as cold water is supplied to the sleeves 8 and 9 of the cooling mold 2 through refrigerant supply ports 14 and 15, cools the mold, and is discharged through refrigerant discharge ports 16 and 17. still,
In many cases, the purpose of cooling is achieved only by blowing air for mold release, and the above-mentioned forced cooling is often not necessary. In addition to the above-mentioned mechanism for supplying and discharging heat medium and refrigerant, these mantle-like parts 6, 7, 8, and 9 also eject compressed air to the front of the mold, or suck air from the surface of the mold to the back. Male molds 1a, 2a and female molds 1b, 2b are used to generate force.
It is preferable to connect the through hole bored in the air to a compressed air supply source or a vacuum generator through an appropriate flow path. The fixed mold 1a of the heating mold 1 is equipped with a resin particle supply device 1.
8 is installed, and its supply port 19 opens toward the mold cavity 3.

The movable mold 2b of the cooling mold 2 has an ejector plate 20 that is fitted into a recess in the inner wall surface of the movable mold 2b and whose surface coincides with the inner wall surface in the fitted state. It is fixed to the tip of a mounted ram 21, and the ram 21 is urged outward by a spring 22 and elastically supported by the formwork. The ejector plate 20 protrudes forward as the free end of the lever 21 is restrained by a stopper when the female mold 2b retreats to open the mold. Here, we have shown an example in which the ejector plate moves forward and backward mechanically.
It goes without saying that any known or commonly used means using hydraulic pressure, pneumatic force, electromagnetic valves, etc. can be applied as appropriate.

The operation will be explained below with reference to FIGS. 1 to 4.

In FIG. 1, with the heating mold 1 closed,
The resin particle feeder 18 is operated to supply and fill the mold cavity 3 with pre-foamed particles of expandable thermoplastic synthetic resin such as expandable polystyrene, expandable polyethylene, etc. through the supply port 19. Heat medium supply ports 10, 11
If a heating medium made of heated gas such as heated steam, preferably at 110 to 120°C, is supplied from
The resin particles enter the mold cavity 3 through the through holes a and 1b, become plasticized, foam further, expand, fuse together, and become integrated. On the other hand, in the cooling mold 2, the molded body in the mold cavity 4 is cooled and hardened by a cooling medium, preferably cooling water, supplied from the cooling medium supply ports 14, 15 to the mantles 8, 9. When heating foaming in the heating mold 1 and cooling solidification in the cooling mold 2 are completed, as shown in FIG. 2, the female mold 1b,
2b are the respective opening/closing movement axes A-A and B-B.
Step back along the line and open the mold. As the female mold 2b of the cooling mold 2 retreats, the lever 21 is stopped by a stopper, and the ejector plate 20 protrudes to extrude and release the product. Furthermore, the heating mold 1 is opened by the retreat of the female mold 1b, but at that time, which mold the foamed resin semi-finished product remains on depends on the mold release resistance of the semi-finished product against the male mold 1a and the female mold 1b. Determined by size. As shown in the figure, the female mold 1b is sufficiently larger than the male mold 1a in terms of the contact area between the semi-finished product and the mold wall, and the peripheral wall surface of the female mold 1b is parallel to the axis A-A, whereas the male When the mold 1a has a tapered shape, the mold release resistance of the semi-finished product against the female mold 1b is sufficiently greater than that against the male mold 1b, and it is certain that the semi-finished product remains in the female mold 1b. It is.

Therefore, in order to have a difference in mold release resistance, it is possible to apply a mold release agent to only one mold, or to blow air from the mold wall in the direction in which the semi-finished product is extruded in one mold, and in the opposite direction in the other mold. Although there is a method of applying a suction force to the mold, it is possible to easily create a sufficient difference in mold release resistance by appropriately designing the shape of the mold cavity, that is, the shape of the female mold and the male mold.

The female mold 1b of the heating mold 1 thus opened moves in the direction of the arrow in FIG. 2 while supporting the semi-finished product, and confronts the male mold 2a of the cooling mold 2.

The female mold 1b then advances along the axis B-B to form the third
As shown in the figure, it is fitted with the male die 2a and then retreated again to the position indicated by the dotted line in FIG. At this time, as is clear from the above explanation, considering the shapes of the female mold and male mold, the semi-finished product will naturally remain in the female mold 1b, so compressed air is supplied to the female mold 1b and it is blown out from the inner wall surface. A male mold 2a that applies a force to push out the semi-finished product and at the same time adsorbs the semi-finished product to the surface of the male mold 2a.
The female mold 1b is retracted while a negative pressure is generated behind it by a vacuum pump or the like, and the semi-finished product is then transferred to the female mold 1.
b to male type 2a.

After completing the transfer, the female mold 1b moves in the direction of the arrow in FIG. 4 and confronts the male mold 1a, and then both female molds 1b and 2b move forward to form their respective male molds as shown in FIG. Fits into molds 1a and 2a.

The above is the general operation or action of a transfer molding apparatus, but one of the technical problems that reduces its working efficiency and product yield is the transfer error mentioned above.

In other words, depending on the shape of the female and male molds, if the mold release resistance from the male mold is relatively small, or if compressed air leaks or vacuum leaks are likely to occur, transfer errors often occur. . Therefore, the key point of the present invention is that the fixed male mold 2a in the figure of the cooling mold 2
A pin 23 having an axis parallel to the opening/closing motion axis B-B of the mold 2 is implanted at an appropriate location on the molding surface, that is, the surface in contact with the molded body, and the cooling fixed male mold 2a is
The present invention consists in increasing the mold release resistance value of the molded product. Of course, depending on the mold configuration, a pin may be provided on the female mold 2b to increase the resistance value.

By the way, as the heating movable female die 1b moves forward, the pin 23 enters into the semi-finished product that is closely fitted, and the pin 23
The withdrawal resistance increases due to the contraction of the resin in contact with the periphery of the mold 2a, and as a result, the mold release resistance value of the semi-finished product from the cooled and fixed male mold 2a increases, thereby ensuring the transfer of the semi-finished product.

If the pin 23 is implanted only in the cooling fixed male die 2a, it may leave large scars on the molded body and spoil its appearance.
In order to prevent functional deterioration, it is extremely preferable to attach a plurality of needle-shaped pins.

In addition, the heating mold corresponding to the cooling fixed male mold 2a in which the pin 23 is implanted, that is, the heating fixed male mold 1a, is attached at the same place and in the same posture as the cooling fixed male mold 2a, that is, with the opening/closing movement axis A-A. The pins 24 are installed so that their axes are parallel to each other, so that the pins 24 close the pores 25 of the semi-finished product formed in the heating mold 1.
Since the cooling type pin 23 is inserted easily into the mold, even if a pin of relatively large size is used, the molded product will not be locally deformed or destroyed due to intrusion pressure, and the mold release resistance will be significantly reduced. can be increased. In this case, by making the cooling type pin 23 and the heating type pin 24 equal in shape and size, the effects of the device of the present invention can be sufficiently achieved. That is, the pores 25 formed in the semi-finished product by the heating type pin 24 become narrowed until the resin, which is still slightly expanding and expanding, completes foaming, and the cooling type pin 23 is inserted therein. This is because the resin at the contact portion cools and solidifies, thereby increasing the resistance of the pin 23 to pull out.

The diameter of the pin 23 of the cooling fixed male mold 2a at least in part of its entire length is made larger than the diameter of the pin 24 of the heating mold 1a in order to ensure the anchoring effect of the semi-finished product by the pin 23. It is extremely effective. Such an example is shown in FIG. In the figure, the cooling type pin 23' is
The diameter is uniformly larger than the diameter of the heating type pin 24 over its entire length, and both pins 23'', 23 have a diameter larger than that of the pin 24 over a portion of their entire length.

Furthermore, making the surface roughness of the pins 23 of the cooling fixed male mold 2a larger than the surface roughness of the pins 24 of the heating male mold 1a is also an effective method for increasing the effects of the present invention.

The dimensions of the pin 23 depend on the size and shape of the molded product, but it is usually 6 mm to 20 mm in diameter, preferably 6 mm to 10 mm, and preferably 15 to 75 mm in length.

Furthermore, the pin 24 of the heat-fixing male die 1a can be replaced with a member for thinning molding. At this time, if there is a channel-shaped thinning along the surface of the core, even if the pin 23 of the cooling fixing male mold 2a is inserted therein, the effect is weak. Therefore, it is important that the meat stripping be in the shape of a tube or a tunnel, and in this case as well, consideration should be given to the relationship in shape and size between the meat stripping forming member and the pin 23 to satisfy the above-mentioned conditions.

The cooling stationary male mold 2a, which has received the semi-finished product from the heating movable female mold 1b as described above, is transferred to the cooling movable female mold 2b.
After the semi-finished product is cooled and solidified to form a stable molded body, the cooling movable female mold 2b is retracted, but at this time, the molded body is moved onto the fixed male mold 2a by the action of the pin 23. Transfer errors may also occur here. In order to prevent this, it is possible to blow compressed air from the male mold 2a to push the molded product to the front, and at the same time, vacuum the surface of the female mold 2b to adsorb the molded product, but the air system In order to avoid unnecessary complications, a pin having an axis parallel to the B-B axis is implanted at an appropriate position on the inner wall surface of the female mold 2b to separate the fixed cooling male mold 2a and the cooling movable female mold 2b. It is possible to reliably reverse the mold release resistance of the molded product.

In this way, the molded body is reliably transferred to the cooling movable female mold 2b, and the molded body is extruded by the action of the ejector plate 20 that protrudes as the movable female mold 2b moves backward, and is recovered as a product. be.

As detailed above, the foam molding mold according to the present invention is very conveniently applied to the transfer molding method. In other words, in the transfer molding method, which greatly contributes to process rationalization and productivity improvement by shortening process cycle time and saving energy,
To reliably eliminate the transfer error of semi-finished products, which has traditionally been a major problem, by making simple improvements and modifications to the equipment and easily and arbitrarily changing the release resistance value of the semi-finished product from the mold. is possible,
In addition, it greatly contributes to the use of the transfer molding method, such as improving work efficiency and yield without impairing the appearance and performance of the product.

[Brief explanation of drawings]

FIGS. 1 to 4 are schematic diagrams for explaining the structural aspect and operating sequence of the apparatus of the present invention. Fifth
The figure is a side view showing the shape of a pin that constitutes a main part of the device of the present invention. 1... Heating type, 2... Cooling type, 1a, 2a...
Male type, 1b, 2b... female type, 3, 4... type fossa, 1
8...Resin particle supply device, 19...Resin particle supply port, 20...Ejector plate, 23, 24...
Pin, A-A, B-B...Opening/closing movement axis.

Claims (1)

[Scope of Claims] 1. Consists of two sets of molding molds each having a pair of male and female molds that can be opened and closed with each other to form a mold cavity, the first molding mold forming a mold cavity. The second mold is a heating mold equipped with a supply port for foamable thermoplastic resin particles and a means for heating the inside of the mold cavity. Furthermore, the male mold of one mold and the female mold of the other mold fit into each other by movement of either one, and the molded object supported by the heating mold is transferred to the cooling mold. In a transfer molding apparatus configured to transfer the molded product to a molded body, a pin having an axis parallel to the opening/closing movement axis of the mold is implanted at an appropriate location on the surface of the cooling mold which receives the molded product, which is in contact with the molded product. 1. A mold for foam molding, characterized in that the molding mold is provided with a cooling mold and increases resistance to releasing the molded product from the cooling mold. 2. The foam molding mold according to claim 1, wherein the pins are in the form of a plurality of needles. 3. A cooling type with pins installed and a corresponding heating type.
A mold for foam molding according to claim 1, wherein pins are implanted in the same positions and in the same posture as the cooling mold. 4. The mold for foam molding according to claim 3, wherein the pin of the cooling mold and the pin of the heating mold have the same shape and dimensions. 5. The foam molding mold according to claim 3, wherein the cooling type pin has a diameter larger than the diameter of the heating type pin over at least a portion of its entire length. 6. A mold for foam molding according to claim 3, wherein the pin of the heating mold is a member for molding with thinning material. 7. The foam molding mold according to any one of claims 3 to 6, wherein the pin has a diameter of 6 mm to 20 mm and a length of 15 mm to 70 mm. 8. The foam molding mold according to claim 7, wherein the pin has a diameter of 6 mm to 10 mm. 9. A mold for foam molding according to any one of claims 3 to 8, wherein the surface roughness of the cooling type pin is greater than that of the heating type pin. 10 Claims 1 to 9, in which the mold cavity shape of the heating mold is defined so that the mold release resistance of the heating mold that is to support the molded object is greater than the mold release resistance of its counterpart heating mold. The foam molding mold according to any one of the above. 11. Claims 1 to 1, in which pins are implanted in the cooling mold opposite to the cooling mold in which the pin is implanted in a similar manner, and the mold release resistance of both cooling molds is reversed.
The foam molding mold according to any one of Item 1. 12 The heating mold that controls the transfer of the molded product is equipped with a means for injecting compressed gas from the inner wall surface of the mold toward the molded product, and the cooling mold that receives the molded product is equipped with a means that generates negative pressure from the inner wall surface of the mold toward the back of the mold. A mold for foam molding according to any one of claims 1 to 11, comprising a tightening means.