JPH0137255B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Object of the Invention [Field of Industrial Application] The present invention relates to a method for molding a thermoplastic resin plate (including a sheet, hereinafter simply referred to as a resin plate).

[Conventional technology]

In thermoforming processes such as vacuum forming, pressure forming, press forming, etc. of resin plates, it is necessary to uniformly heat the entire surface of the resin plate, which is the material to be processed, in advance so that each part of the resin plate is uniformly softened by heat.

As a means of heating the resin plate, a radiation heating method using an electric heater such as a nichrome wire heater, sheathed heater, or infrastructural heater as a heat source is generally adopted, and other methods such as hot air blowing method and hot plate contact method are also used. be.

[Problem that the invention seeks to solve]

However, the radiation heating method has many problems with the uniform heating accuracy of the heater, and it is difficult to heat and soften the resin board uniformly and substantially evenly over the entire surface, requiring a high degree of skill and delicate process control. .
Moreover, it cannot be said that the thermal efficiency is good and the heat loss is large.

The same can be said of the hot air blowing method, and its thermal efficiency (thermoeconomic efficiency) is worse than the above-mentioned radiant heating method.

The hot plate contact method heats the resin plate by bringing the resin plate into contact with the hot plate surface and directly conducts the heat from the hot plate to the resin plate, so it has good thermal efficiency and good thermoeconomics. However, even with this hot plate contact method, when the resin plate is brought into contact with the hot plate and heat treated, wrinkles may occur during the softening process due to the internal strain inherent in the resin plate, and the gap between the hot plate and the resin plate may occur. Due to the presence of the trapped air layer, it is difficult for the resin plate to come into full contact with the surface of the heating plate, and as a result, uneven heating is likely to occur.

Therefore, methods are known in which the hot plate is equipped with a vacuum suction function to actively bring the resin plate into close contact with the hot plate surface, and furthermore, compressed air force is applied to press the resin plate against the hot plate surface (for example, Publication No. 50-13899, Publication No. 50-13900, Kazuo Asano, “On-site Manual Volume IX, Heat Processing and Forming Edition” (September 1971),
Maruzen, pp. 34 and 35). This method is quite effective in uniformly heating and softening a resin plate. However, the upper limit of the vacuum force is 1 atm, and the pneumatic force cannot be unnecessarily increased in pressure due to the sealability of the chamber, safety, etc., and is limited to a low value below a certain level. Therefore, in practice, the wrinkle-generating force due to the internal strain of the resin plate often sufficiently overcomes the vacuum suction holding force and the compressed air pressing force, causing wrinkles and uneven heating due to this.

The present invention is also a method for forming a thermoplastic resin plate, which includes a step of heating and softening a resin plate using a hot plate equipped with a vacuum suction function. (2) As a workpiece material, the resin plate can be brought into close contact with the hot plate surface in each part without causing wrinkles, no matter how large the wrinkle-generating force due to internal strain is. Using a long resin plate, the long resin plate can be efficiently heated and softened and molded sequentially starting from the tip. (3) Large size that can be extremely softened and easily drawn down. It is an object of the present invention to provide a method for molding a thermoplastic resin plate, which has the following advantages: a softened resin plate can be applied to a mold and properly molded without causing drawdown deformation.

B. Structure of the Invention [Means for Solving the Problems] That is, the present invention provides a process for intermittently feeding a long thermoplastic resin plate by a predetermined length onto a hot plate surface having a vacuum adsorption function; The resin plate portion sent out is brought into close contact with the hot plate surface by the vacuum suction force of the hot plate, and a press plate having a vacuum suction function is brought into contact with the side opposite to the hot plate side of the resin plate portion. The process of sandwiching the resin plate part between the hot plate and the pressing plate on a sander bench and allowing it to be thermally softened as required by the heat of the hot plate. The step of holding the press plate in close contact with the press plate surface by the vacuum suction force of the press plate and transferring it to the molding station, from the time when the resin plate is fed out for a predetermined length to the hot plate surface, the heat softening resin plate is heated by the press plate. Before the start of the transfer of the parts to the molding station, the resin plate part on the hot plate side is cut and separated from the following resin plate part, held tightly against the pressing plate surface, transferred to the molding station, and applied to the mold. This method of molding a thermoplastic resin plate is characterized by the steps of releasing the vacuum suction holding of the thermosoftened resin plate portion by a press plate, and molding it in a mold.

[Effect]

The heat softening of the resin plate portion delivered to the hot plate surface is achieved by bringing the resin plate portion into close contact with the hot plate surface due to the vacuum adsorption force of the hot plate, and also by bringing the resin plate portion into close contact with the hot plate surface on the side opposite to the hot plate side. Since the pressure plates are in contact with each other and the resin plate part is sandwiched between the hot plate and the press plate in a sandwiched state, the wrinkle-generating force due to internal strain during the softening process of the resin plate is absorbed by the vacuum of the hot plate. No matter how much larger the adsorption force is, the resin plate is sandwiched between the hot plate and the pressing plate by a sander bench and is held down, so no wrinkles can actually form and the resin plate maintains full adhesion to the hot plate surface. Then, each part of the resin plate is heated and softened evenly.

In this case, the pressing force of the press plate against the hot plate surface of the resin plate can be applied without applying any active pressing force if the press plate surface is held immovably in close contact with the resin plate surface. Full-scale adhesion to the plate surface is sufficiently maintained (actively applying a large pressing force is not preferable as it will actually crush the softened resin plate).

That is, the resin plate can always be easily and uniformly heated and softened without the problems described above when pressing the resin plate against the hot plate surface using pneumatic pressure.

The resin plate portion that has been heated and softened as required between the hot plate and the press plate is held in close contact with the press plate surface by the vacuum suction force of the press plate after releasing the vacuum suction force on the hot plate side, and then moved to the molding station. (Please note that the heat-softened resin plate portion is not allowed to be heated or softened during the period from the end of feeding the required length of the resin plate to the hot plate surface to the start of transfer to the molding station by the press plate. cut and separated from the resin board part),
Even a large and sufficiently softened resin plate that is prone to drawdown can be transferred to the molding station and applied to the mold without deformation due to drawdown, and therefore the resin plate is always in a good condition. Can be molded.

Then, a long resin plate is used as the material to be processed, and it is intermittently sent out over a predetermined length onto the hot plate surface to undergo the heating softening, cutting, transfer to the molding station, and molding process as described above. Continuous and efficient molding of thermoplastic resin plates is possible.

〔Example〕

In FIG. 1, reference numeral 1 denotes a long resin plate as a workpiece material wound into a roll, and is intermittently fed out by a feed-out conveyance mechanism not shown in the figure.

3 is a hot plate (metal, ceramic, etc.) fixedly arranged with the heating surface 31 facing upward and horizontally, and the resin plate 1
It has approximately the same width dimension as . It has approximately the same length as the intermittent feed length of the resin plate 1. Reference numeral 32 denotes a heating medium feed pipe buried within the thickness of the hot plate 3, which is arranged in a meandering manner within the plane of the hot plate or in parallel arrays so that the hot plate 3 is heated evenly over the entire surface. It is provided. 33 is a small diameter vacuum suction hole opened in each part of the hot plate heating surface 31, 34 is a communication chamber for each vacuum suction hole formed on the back side of the hot plate, and 35 is a vacuum pipe opened in the communication chamber. , is in contact with the vacuum pump (not shown). Due to the operation of the vacuum pump, each vacuum hole 33 enters the state of sucking outside air, and the hot plate heating surface 3
1 is in a vacuum suction state.

A forming station 2 is installed next to the hot plate 3, and in this example, a vacuum forming mold 5 is installed. 5
1 indicates a vacuum hole.

4 is a pressing plate (metal,
The pressing plate is made of ceramic, etc.), and the pressing plate is moved downwardly relative to the hot plate 3 by a carrier mechanism (not shown), with the position indicated by the solid line above the hot plate 3 as the home position.
Movement control is performed for upward movement, forward movement to the molding station 2, downward movement and upward movement of the molding station relative to the mold 5, and return movement to the molding station 2. 43 is a vacuum suction hole opened at various places on the pressing surface 41 of the pressing plate, 44 is a communication chamber of each vacuum suction hole, and 45 is a vacuum pipe opened to the chamber, which is connected to a vacuum pump (not shown). I'm in touch. By the operation of the vacuum pump, each vacuum hole 43 enters an outside air suction state, and the pressing surface 41 of the pressing plate enters a vacuum suction state. In this example, the press plate 4 is also provided with a hot plate function, and 42 indicates a heating medium feed pipe buried within the thickness of the press plate 4 in the same manner as the hot plate 3 described above.

Pipes 32, 4 for heating the hot plate 3 and press plate 4
The heat medium passed through 2 is oil, nitrates, steam, etc. heated by the combustion heat of heavy oil. Heating by these methods can achieve higher thermal economy than electric heating. Of course, the heating plate 3 and the pressing plate 4 may be heated by electric heating.

The resin plate 1 is connected to the heating surface 3 of the hot plate 3 while the press plate 4 is waiting at the home position shown by the solid line.
1 side for a predetermined length. When the resin plate 1 is fed out for a predetermined length, the feeding of the resin plate 1 is temporarily stopped, and the hot plate 3 is maintained in a vacuum suction state.
As a result, the resin plate portion sent out to the hot plate surface is vacuum-adsorbed to the hot plate 31 of the hot plate and brought into close contact. Further, the cutter 7 is operated to cut and separate the resin plate portion sent out to the hot plate 3 side from the following resin plate portion. On the other hand, the pressing plate 4 is moved downward and covers the resin plate portion of the hot plate surface, and the resin plate portion is sandwiched between the hot plate 3 and the pressing plate 4 in a sanderch, thereby reducing the heat of the hot plate 3 and the present example. In this case, the material is further heated and softened by the heat of the pressing plate 4. As explained in the section of the above-mentioned function, this allows the resin plate portion to be heated evenly and uniformly throughout the resin plate, and to be heated and softened uniformly throughout.

When the predetermined heat treatment time has elapsed, the vacuum suction on the hot plate 3 side is released, the press plate 4 side enters the vacuum suction state, and the heated and softened resin plate portion is transferred to the hot plate 3.
It is held by vacuum suction from the side to the pressing plate 4 side. Next, the press plate 4 moves upward, moves forward to the molding station 2, and moves the station 2 downward with respect to the mold 5, and the heated softened resin plate held by vacuum suction on the press plate 4 is applied. This transfer of the heat-softened resin plate from the hot plate 3 side to the molding station 2 side is caused by the fact that the heat-softened resin plate is entirely held by vacuum suction on the press plate 4, so the resin plate is large.
Even extremely softened products can be processed without causing drawdown deformation.

When the holding resin plate is applied to the mold 5 by lowering the press plate 4 (indicated by a two-dot chain line), the vacuum suction of the press plate 4 is released, and the molding process of the resin plate by the mold 5, in this case vacuum. A molding process is performed. In this case, air may be blown out from each vacuum hole 43 of the pressing plate 4 to form or assist in forming the resin plate by pneumatic force.

The press plate 4 then moves back to its home position again for the next cycle of heating, conveying and molding the resin plate section.

In this manner, by repeating the above steps, long resin plates can be efficiently molded one after another. Since there is no heating unevenness or drawdown in the resin plate material, high-quality molded products can be mass-produced with a high yield.

The heating surface 31 of the hot plate 3 and the pressing surface 41 of the pressing plate 4 are processed with fluororesin or silicone resin to prevent the softened resin plate from sticking.

The hot plate 3 and the press plate 4 may be made of an air-permeable porous fleshy material. In this case, vacuum hole 33 or vacuum hole 43
There is no need to force it to form.

C. Effects of the Invention As described above, according to the present invention, it is possible to efficiently mass-produce high-quality molded products by successively heat-softening and molding long resin plates. The objectives of the period are well achieved.

[Brief explanation of drawings]

The drawing is a schematic process diagram of one embodiment of the method of the present invention. 1 is a long resin plate which is a material to be processed, 2 is a molding station, 3 is a heating plate, 4 is a press plate, 5 is a vacuum mold, and 7 is a cutter.

Claims (1)

[Scope of Claims] 1. A step of intermittently feeding a long thermoplastic resin plate by a predetermined length onto a hot plate surface having a vacuum suction function; A pressure plate having a vacuum suction function is brought into close contact with the heating plate side and the opposite side of the resin plate part using the vacuum adsorption force of the heating plate, and the resin plate part is placed in a sandwich between the heating plate and the pressing plate. The process of putting the resin plate in a sandwiched state and softening it as required by the heat of the hot plate, releasing the vacuum suction force of the resin plate of the hot plate, and applying the vacuum suction force of the press plate to the thermally softened resin plate part on the surface of the press plate. The step of holding the resin plate in close contact and transferring it to the molding station, from the time when the resin plate finishes feeding out a predetermined length to the hot plate surface to the time when the press plate starts transferring the thermosoftened resin plate portion to the molding station. In this process, the resin plate part on the hot plate side is cut and separated from the following resin plate part.
A method for molding a thermoplastic resin plate, comprising the following steps: releasing vacuum suction and holding by a pressing plate, and performing molding treatment in a mold. 2. The method for molding a thermoplastic resin plate according to claim 1, wherein the press plate has a hot plate function. 3. The method for molding a thermoplastic resin plate according to claim 1, wherein the surfaces of the hot plate and the press plate that come into contact with the resin plate are treated to prevent adhesion of the softened resin plate.