JPS6362380B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The method of heating a sheet material for a resin sheet molded product according to the present invention relates to a molding method that employs a method of heating a resin sheet as a material to a moldable temperature before molding with a molding machine. It is.

The main object of the present invention is to minimize the bending distortion that occurs in the pre-forming heating region of the material sheet.

Regarding the heating method in the conventional method in which this type of resin sheet is used as a material, the sheet material is heated before molding, transferred to the mold area, and then molded.
One method involves blowing hot air heated to 180 to 220 degrees Celsius from the top and bottom of the material while the material is floating in the middle of the heating area, and the other method uses direct heating using radiant heat such as an electric heater or radiant heat. A method using a heating means such as an indirect heating method is generally used. However, in any case, depending on the degree to which the sheet material is heated and softened, the central part of the sheet material will gradually sag due to its own weight, and the center part of the sheet material will gradually sag due to its own weight. The drawback was that it became thin near the parts.

For this reason, it has been impossible to eliminate the non-uniformity of the product due to the thickness of the material sheet. In particular, for products (molded products) in which the material sheet must be deeply uneven in the thickness direction, there is a drawback that some molded products may break and lose their commercial value.

Furthermore, when the material sheet is printed, the bending and distortion phenomena during heating have the disadvantage that non-uniformity of the product can be seen visually. A particular problem is that in recent years it has become necessary to attach barcodes (also known as boss marks) to various products, and if this barcode is printed on the material, the material cannot be If bending or distortion occurs during heating, the barcode itself will no longer be able to perform its original function, which is a fatal drawback.

The present invention provides a method for heating a material sheet that eliminates such conventional drawbacks.

That is, first, a sheet-like material made of thermoplastic synthetic resin is transferred to a heating area in a substantially horizontal direction by a transfer device. Then, on a container filled with the heated molten liquid, the sheet-like material is supported in contact with the surface of the heated molten liquid and heated. Subsequently, the sheet material is transferred to a molding area and molded using a mold. At this time, the sheet material is directly supported by the surface of the heated liquid that is filled to overflow in a container placed close to the lower side of the transfer line of the heated sheet material, and at the same time, the heated liquid is transferred to the sheet. By directly heating the material and simultaneously using the heating liquid to directly heat the sheet material, the sheet material will not sag due to its own weight even when heated. Moreover, since the object that supports this sheet material is a liquid and has fluidity itself, the material supporting surface always remains horizontal, and when the heated material is transferred to the forming area, it does not interfere with the material. Since the abutment support surface itself continues to support the material and acts in the direction of movement of the material as it moves, the material will not stretch due to the sagging phenomenon even when it is moved after heating. do not have.
In particular, by arranging the container so that the molding area side is slightly lower, or by making the upper edge of the container on the molding area side slightly lower, the heated liquid can easily overflow into the molding area side. If this is done, the heated liquid itself acts as a means to transfer the material to the forming area, making it easier to transfer the heated material to the forming area more smoothly and evenly. There is an effect.

Various types of resin sheets can be used as thermoplastic synthetic resin sheets, but in the case of polyethylene or vinyl chloride, the heat distortion temperature is relatively low in the case of polyethylene, at 43 to 49℃, and it is higher than that of vinyl chloride (hard). The temperature is relatively high at 70-80℃. In the case of an egg container, strength is required depending on the number of eggs stored, a large volume is required, and a large amount of heat capacity is required as the outer shape and shape are adjusted. Proportionally, for example, if molten solder is used as a heating liquid, the material is easy to obtain, the cost is relatively low, and temperature control (50 to about 500°C) and handling are very convenient.

An embodiment of the method of the present invention will be described based on the drawings.

As shown in FIG. 1, a synthetic resin sheet material 1 is wound into a roll and is suspended from a shaft 12 so as to be freely drawn out. As shown by chain lines in FIG. 2, this sheet-like material 1 is adapted to be transferred in the horizontal direction by being held at both longitudinal edges by transfer chains 2 disposed above and below. . A heating zone A, a forming (processing) zone B, and a cutting (processing) zone C are sequentially provided from the base end side of this material transfer path, and the heating zone A is filled with heating liquid 4 at a position directly below the material transfer path. The container 4 is placed close to the material 1 so that its upper edge touches or is slightly separated from the material 1, and is filled with liquid so that the liquid surface is in contact with the material 1 when the material 1 is heated. heating liquid 3
The solder, which melts at 180° to 150° Celsius, is heated and melted in a heating tank T and sent to a pump P via pipes 8 and 8.
The solder that is fed into the container 4 and overflows and falls is guided by a receiving gutter 7 and collected into the heat tank T. In the forming area B, a mold consisting of a male die 5 and a female die 5' of the material 1 is arranged, and in the cutting area C, a cutting device consisting of a cutting blade 6 and a cutting receiving blade 6' is arranged. The details of these molds and cutting devices will be omitted since they are the same as conventional ones. In the figure, 9 and 9 are material transfer rolls;
Reference numeral 1' indicates a remaining sheet portion after cutting the molded product, and reference numeral 51 indicates a molding recess formed on the upper surface of the female mold 5'.

During molding, the solder (heated liquid) 3 heated and melted by the heating tank T is replenished by the pump P to the extent that it always overflows into the container 4, and the heating area A is
The sheet material 1 transferred to is heated while being supported in contact with the surface of the solder on the container 4, and at the same time, the portion of the material 1 that was previously heated and transferred to the forming area B is formed by the forming molds 5 and 5'. The process of cutting the formed portion, which has been heated two times before and has been transferred to the cutting area C, into a predetermined container shape by the cutting devices 6 and 6' is performed intermittently and sequentially.

The melting temperature of the heating liquid 3 in the present invention must be set based on the softening temperature and thickness of the sheet material, as well as the time required for molding with a mold, that is, the heating time. In the case of rotating packaging containers for eggs, (as mentioned above, it largely depends on the performance of the molding machine)
As a result of experiments, a temperature of about 130° to 150° Celsius is optimal.

The material of the molten liquid used in the present invention may be water, volatile liquid, low-temperature molten metal, etc., as long as it is liquid or liquefied by heating, and the sheet material is
Water may be used as long as it is a synthetic resin that softens to a moldable state at 100° or less, but if solder is used as in the above example, solders with different melting temperatures can be selected, so the temperature setting It is a material that is extremely suitable for carrying out the present invention because it is easy to mold, does not easily adhere to resin materials, and even if it does adhere, it solidifies after molding and falls off from the product.

[Brief explanation of drawings]

FIG. 1 is a schematic side view of the arrangement of an apparatus used for carrying out the present invention, and FIG. 2 is a perspective view of the main parts thereof. 1...Sheet material, 2...Transfer device, 3...
Heated melt, 4... Container, 5, 5'... Molding mold,
A: Heating area, B: Molding area.

Claims (1)

[Scope of Claims] 1. A sheet material 1 made of synthetic resin is transferred approximately horizontally to a heating area A by a transfer device 2, and placed on a container 4 filled with a heated melt 3.
A sheet material for a resin sheet molded product, in which the material 1 is brought into contact with and supported on the surface of a heated melt 3 and heated, and then the material 1 is transferred to a molding area B and molded by molds 5 and 5'. Heating method. 2. The sheet material heating method for a resin sheet molded product according to claim 1, wherein the heated melt 3 is solder. 3. A sheet material heating method for a resin sheet molded product according to claims 1 to 3, wherein the temperature of the heated melt 3 is set in the range of 130 to 150 degrees Celsius. 4. A sheet material heating method for a resin sheet molded product according to claims 1 to 3, wherein the heated melt 3 is a heated circulating liquid.