JPS61139419A - Forming method of foamed sheet - Google Patents

Abstract

PURPOSE:To manufacture a good foam-molded piece requiring no trimming by heating and forming a foamed sheet veneer laid on an air-permeable carrying member preventing the veneer from moving from the fixed position. CONSTITUTION:The foamed sheet veneer P cut to a specified size is laid on the air-permeable carrying member S such as glass fiber fabric etc. and moved to a heating part 3. Said veneer P is heated and softened by heating plates 30, 31, then, said veneer is formed into a desired shape in a forming part 4 and a formed piece M is taken out. Vacuum forming is performed by using the bottom force 42 with air blowout holes 43 and the top force 40 with a vacuum suction hole 41. Pressure forming can be used after vacuum suction forming. Since a specified carrying member is used, clamps etc. are not required, positioning is correct, no trimming is needed and material sheet can be used efficiently.

Description

[Detailed Description of the Invention] <Technical Field> The present invention relates to a method for molding a foamed sheet, in which a foamed sheet of thermoplastic resin is heated and softened, and then a cored sheet is thermoformed along a mold to form a desired molded product. It concerns the method of manufacturing.

<Prior art> The method for forming the above-mentioned foamed sheet is usually to continuously run a long roll-shaped cored sheet and feed it sequentially through a heating furnace to a mold, and then to a multi-cavity mold. A molding method is used in which a plurality of molded products are molded at one time, the molded foam sheet is punched or cut, and each molded product is trimmed to obtain a single molded product.

The disadvantage of the above method is that a large amount of unnecessary scrap is generated between the molded products of the foam sheet during trimming, resulting in a large amount of wasted foam sheet and poor yield. In addition, because many molded products are molded at once, the finished product may vary depending on the position within the mold, resulting in increased bulk and defective products, which makes mold design extremely difficult. there were.

Therefore, a method has been proposed in which the foam sheet is cut into pieces for each single molded product in advance, and the foam sheet LP plates are individually molded using a mold for single molded products. It has the effects of saving time and effort, improving the quality of molded products, and reducing the occurrence of defective products. .

However, in the single molding method described above, it is necessary to transport the foam sheet veneer to the heating process or molding process and handle it, which is extremely difficult and troublesome. . That is, if the foam sheet veneer is not held and handled reliably, for example, the foam sheet that has softened during heating will deform before molding, making it impossible to use it in the molding process.

Furthermore, in the molding process, if the foam sheet veneer is not set accurately in the mold, there will be problems such as misalignment of the molding or eccentricity of the finished molded product.

Furthermore, since the heating process and molding process are performed while holding the centering sheet veneer, it is necessary to hold it so as not to interfere with these process operations. As described above, there have been many problems in reliably holding small foam sheet veneers.

Moreover, when clamping the ends of a foam sheet veneer, the clamp width must be wide to ensure secure clamping in order to withstand the thermal shrinkage force during heating.

However, this clamp location becomes a scrap part that cannot be used for molding, resulting in the same kind of waste of the foam sheet as in the multi-cavity molding method described above. Another disadvantage is that heat is absorbed by the clamp member during heating, making it difficult to uniformly heat the entire surface of the foam sheet veneer.

Therefore, it is an object of the present invention to provide a molding method that eliminates the drawbacks of the above-mentioned prior art and allows for good handling of foam sheet veneers in molding each single molded product.

<+ll;Synthesis> The method for achieving the above objective is to heat and soften a foamed sheet of thermoplastic MA resin and thermoform it along a mold. The foamed sheet veneer is cut into veneers, placed on a conveying member with air permeability, and transported from the heating process to the molding process.In the heating process, the foamed sheet veneer is heated and softened, and then molded. It is characterized by thermoforming in the process.

<Example> Next, an example of the present invention will be described below with reference to the drawings.

FIG. 1 schematically shows the construction of a molding apparatus used to carry out the method of the present invention, and is a molding apparatus for molding and manufacturing cup-shaped containers as molded products.

First, (1) is the veneer storage section, which is a veneer (P) cut from a thermoplastic resin foam sheet such as a foamed polystyrene sheet into a size and shape corresponding to the shape of the molded product to be molded.
, stack and store them in this veneer storage section (1). (
10) is the guide part, which is a stacked foam sheet veneer (
P) to restrict lateral slippage. (11) is a weight, which is placed on top of the stacked foam sheet veneer (P) and presses it downward. The lower part of the plate storage section is open, and the foamed sheets are successively pushed downward and taken out by the load of the weight.

('2J is a transport conveyor, which is installed so that it can run freely from the bottom of the veneer storage section (1), through the heating section and molding section, which will be described later, to the take-out position of the molded products.Then, the transport conveyor (2 The running belt (20) is not an ordinary rubber belt or the like, but is formed of a sheet-like conveying member (S) with a large number of small ventilation holes formed through it on one side.The conveying member (S) is A sheet made of woven glass fibers is impregnated with a fluorocarbon resin, and has a thickness of about 100 to 500 μm.

In order to form a large number of ventilation holes in the conveyance member 9 (S), O-cuts are made at a length of 5 to 151 m.

Further, on the surface of the conveyor belt (20), along the longitudinal direction, at equal intervals corresponding to the length of the foam sheet veneer (P),
A stopper (21) is formed. Then, the transport conveyor (2 is installed directly below the deck storage section (1), and the lowest foam sheet veneer (P) of the veneer storage section (1) is transferred to the transport belt (20) of the transport conveyor (2). The single foam sheet (P) is held in the middle of the stopper (21) and pushed forward by the stopper (21) to be conveyed to the next process.

Next, G) is a heating section, and among the running surfaces of the conveyor (2), the running belt (20) adjacent to the veneer storage section (1)
) is equipped with an upper heating plate (30) that can be raised and lowered by a cylinder mechanism, etc., and a running belt (20).
In contact with the bottom surface of the veneer storage i! ! The lower heating plate (31) that extends from the lower part of the upper heating plate (30) to the lower part of the upper heating plate (30) is fixedly installed. It is shaped like a thick plate,
It has a built-in cartridge heater and can be heated freely.

Then, at the stage when the foam sheet veneer (P) is supplied from the veneer storage section (1) onto the conveyor (a), the lower heating plate (
31), heating is started. Next, when the transport conveyor (2J runs, the foam sheet veneer CP is transported below the upper heating plate (30)), the upper heating plate (
30) descends, and between it and the lower heating plate (31) a conveyor belt (made of a single foam sheet (P) and a conveyor member (S)
21) are sandwiched and pressed to heat the foam sheet veneer (P) and simultaneously compress it in the thickness direction.

Next, a molding section (4) is installed adjacent to the heating section (3), and above the running conveyor belt (20) there is a concave upper mold (40) corresponding to the desired shape of the molded product. is provided so that it can be raised and lowered by a cylinder mechanism m or the like. A vacuum suction hole (41) is formed in the upper mold (40), and a foamed sheet veneer (P) is formed by vacuum forming. The vacuum suction hole (41) is also formed to allow pressure air to be blown out, and when the molded product is to be removed from the mold after molding, the pressurized air is blown out to facilitate removal from the mold.

A substantially flat lower mold (42) is provided below the conveyor belt (20), and this lower mold (42) holds the conveyor belt (20) and the foam sheet veneer (P) in between, and presses the upper mold. It is fixedly installed in contact with the lower surface of the conveyor belt (20) so that it can come into contact with the mold (40). (43) is an air blowing hole, which is formed on the upper surface of the lower mold (42) and blows pressurized air upward to blow the foam sheet veneer (P) on the conveyor belt (20) into the mold (40). Press to the side.

Roughly speaking, there is a molded product removal section (5) adjacent to the molding section (4).
) is provided, and the molded product (H
) is taken out to the side of the molding section (4) by the conveyor (a),
The molded product ()l) is picked up from the conveyor belt (a) and collected on a take-out stand (50) provided at the bottom of the conveyor belt (20).

Next, the molding method of the present invention using the molding apparatus as described above will be explained in order of steps with reference to FIGS. 2 to 6. However, in the molding method shown in the figure, the %! The structure is slightly different from that of the original.

First, place a foamed polystyrene sheet, etc. on the conveying member (S). The cut foam sheet veneer (P) is supplied and placed (see FIG. 2). In addition, (22) in the figure is the conveyance member (S
) is a fixing frame.

Next, a heating plate (30) is placed on the top surface of the foam sheet veneer (P).
is pressed into contact with the foam sheet veneer (P), and the conveying member (
A heating plate (31) is brought into contact with the foam sheet through the
Fi (P) is heated from both the top and bottom sides to soften it, and at the same time, pressure is applied in the thickness direction (-C) to counter the secondary foaming of the foam sheet veneer (P) that tends to expand and deform in the thickness direction due to heating. (See Figure 3).

At this time, the heater temperatures of the heating plate (30) and the heating plate (31) are set separately, and the heating temperatures are differentiated between the upper and lower surfaces of the foam sheet veneer (P). That is, the heating temperature for the lower surface of the foam sheet veneer (P) is set higher than the heating temperature for the upper surface. By providing this temperature difference, the foam sheet veneer (P) reliably adheres to the conveying member (S) side,
The foamed sheet veneer (P) is partially deformed, wavy or warped, and instead is fed flat to the molding process, resulting in misalignment of the foamed sheet veneer (P) and molding defects during the molding process. can be prevented. Also, heating 1 (30)
The pressing force according to (31) is adjusted appropriately to ensure flattening of the foamed sheet veneer (P), and to set the standard υ1 so that the thickness of the secondary foaming after heating falls within a certain range J.

In addition, the above pressing force is usually 0.5 to 1.58y4
Implemented within a certain degree.

Next, the conveying member (S) and the heat-softened foam sheet veneer (P) are placed at a molding position between the upper mold (40) and the lower mold (42) (see FIG. 4). And the upper mold (40)
and the lower mold (42) are moved into contact with each other to close the mold. At this time, only the outer peripheral edge of the foam sheet veneer (P) is
0) and the lower mold (42) to fix it. After that, vacuum suction is applied from the vacuum suction hole (41) of the upper mold (40), and at the same time, pressurized air is blown from the air blowing hole (43) of the lower mold (42) and blown upward through the ventilation hole of the conveying member (S). 9, the heated and softened foam sheet veneer (P) is pressed along the concave shape of the upper mold (40) to bulge and deform it to form a molded product (H) of a predetermined shape (No. 5 (see figure).

Next, the upper mold (40) and the lower mold (42) are opened, and pressurized air is blown out from the vacuum suction hole (41) of the upper mold (40) to remove the molded product (H). The molded product (H) that has been removed from the mold is carried out of the molding position while being placed on the transport member (Sl), and the molded product 04 is taken out (see FIG. 6).

The molded article (H) molded as described above can be used as is without trimming the outer shape. In addition, among the molded products (H), the above! (40
) and the lower die (42), the outer periphery of the foam sheet veneer (P) becomes the 2-lung portion of the molded product (H).

Among the forming methods explained above, foam sheet veneer (P)
As the thermoplastic resin foam sheet for forming the foam sheet, in addition to polystyrene, foam sheets made of various thermoplastic resins used in ordinary foam sheet molding, such as polyethylene and polypropylene, can be freely used.

Further, as the molded product (H), in addition to the illustrated cup-shaped container, the present invention can be applied to various articles conventionally manufactured by sheet molding, such as various packaging containers.

Next, as the conveying member (S), if it has excellent heat resistance and thermal conductivity during heating, does not have the softened foam sheet veneer (P) attached to it, and has air permeability, In addition to the above-mentioned woven fabric made of glass fiber, various types of fully curved nets, punched metal plates, and even porous materials whose material itself is breathable can be used freely, and these conveying members (S) can be used. It is preferable to impregnate or coat the surface with a fluororesin to prevent the softened foam sheet veneer (P) from adhering. In addition, the conveying member (S) is directly transferred to the conveyor ('2
When used as a conveyor belt (20) for J, the conveyor member (S) must be made of a material with excellent strength and flexibility that can withstand traction and rotation; When using it while fixed to the frame (22) etc.,
High strength and flexibility are not required.

Next, in order to heat and soften the foam sheet veneer (P), the foam sheet veneer (P) may be placed in a heating atmosphere such as a heating furnace, but in order to prevent shrinkage and deformation during heating, The foam sheet veneer (P) that is being heated and softened is placed on a heating plate (30) (3
It is necessary to press from both sides with a tool such as No. 11.

As a molding method for forming the foam sheet veneer (P), if it can be bulged and deformed along the concave upper mold (40), only vacuum suction from the vacuum suction hole (41) of the upper mold (40) can be used. Any of the exemplified methods may be used, such as the vacuum forming method according to the above method, or the above-mentioned vacuum forming method, which combines the blowing of pressurized air from the air blowing hole (43) of the lower mold (42) and the above-mentioned vacuum suction for more efficient forming. Furthermore, a pressure forming method using only the above-mentioned blowing of pressurized air can also be carried out.

Next, in the molded HH, the storage section for the foam sheet veneers (P) has the first structure, in which a large number of foam sheet veneers (P) are stacked horizontally and taken out one by one from below. However, the foam sheet veneer (P) can be easily handled, the structure is simple, and the storage efficiency is good. Things to take out in order starting from the top of the board (P), etc.
It can also be implemented using conventional storage mechanisms for various sheet materials.

As the transport FR structure for the foam sheet veneer (P), the transport conveyor (1) that directly runs the transport belt (20) made of the transport member (S) is suitable because of its simple structure and efficient transport. However, as shown in FIGS. 2 to 6, the conveying member (Sl) is fixedly mounted on a fixed frame (22), and the fixed frame (22) is
2) may be moved.

In addition to moving the conveyor member (S) linearly using the conveyor mechanism, as shown in Fig. It may be moved back and forth. In addition, in the case of the figure,
The fixed frame (22) is moved back and forth only between the heating section (3) and the forming section (4), and the veneer storage section (1) is not particularly provided, but the veneer storage section (1) is installed. If the fixed frame (
22) may be formed to be movable back and forth between the veneer storage section (1), the heating section (3), and the forming section (4) (see Fig. 8). Also, the above cylinder I! 1 m (23), an n-link structure or a crank mechanism may be adopted as appropriate. Furthermore, the veneer storage section (1), the heating section (21), the forming section (3), etc. can be arranged on the circumference, and the conveying member (S) can be placed on a turntable and rotated, etc. Can be configured.

Next, the heating plates (30) (31) are attached to the foam sheet veneer (CP).
To press the heating plate (31) of the lower conveying member (S) (Ill), fix the heating plate (31) of the upper foam sheet veneer (P)
In addition to moving only the side heating plate (30) up and down, both heating plates (30) and (31) may be moved up and down to press against the foam sheet veneer (P). In addition, a heating plate (301 (
Instead of 31), it is also possible to use a cylindrical heating roll and heat the foamed sheet veneer (P) by pressing the heating roll continuously while the foam sheet veneer (P) is running. Furthermore, the heating section (3) may be configured by combining a heating furnace and a press roll or a press plate.

In addition, after taking out the molded product (H) from the upper mold (40),
Although it is possible to collect the molded product (H) manually, it is even better if a conveyor mechanism such as a conveyor structure or a vacuum suction pad is installed to automatically collect the molded product (H). Be efficient.

Roughly speaking, in the modified example shown in FIG.
) is formed of a relatively thick metal plate with good thermal conductivity, etc., and the upper surface of this conveying member (S) is formed with a foam sheet (32) for a2 of (S) indented. At the same time, by integrally attaching the heating heater (33)' to the lower part of the conveying member (S), the heating plate (
31'). This conveying member (for SIM / It is configured to be horizontally movable from the storage section (1) through the upper heating plate (30) to the lower part of the upper mold (40). Note that (25) is a moving rail, and the mounting member (24) allows for smooth movement.

Then, the foam sheet veneer (P) that was dropped from the veneer storage part (1) onto the side of the heating plate (31') was placed in the heating heater (31').
The heating plate (33) is transported from the heating part (3) to the forming part (4) while being heated by the heating plate (33). 31') and the upper mold (40), the foam sheet veneer (P) is held between the mold and the upper mold (40), and the molding process is carried out. Therefore, the heating plate (31') is connected to the lower mold (
43). In addition, in this modification example, the heating plate (31') is mounted on the mounting member (24).
A receiver (51) for the molded product (M) is installed on the side of the molded product (M), and after the molded product (H) is reliably collected, the molded product ( H) can be taken out of the molding device.

According to the molding method of the present invention configured as described above, a foamed sheet veneer (P) is transported by a conveying member (S) having air permeability.
The foamed sheet veneer (P) is handled and transported by the transport member (S), and the heating process and molding process are performed.

Therefore, without using any conventional clamping mechanism,
Can handle foam sheet veneer (P), and can be transported easily! ! :ll
In addition to achieving 200 mm, there is no need to provide an extra ramp width on the outer periphery of the foam sheet veneer (P), so the material sheet can be used efficiently, and the clamp portion remaining after molding can be trimmed. It also eliminates the need for effort. In addition, the clamp does not damage or deform the foam sheet veneer (P), which will not give an adverse F If to molding or cause molding defects.

Since the conveying member (S) has air permeability, in the molding process, the single heat-softened foam sheet (P) is placed on the conveying member (S). Pressurized air is blown from below the foam sheet veneer (P
) can be pressed against the upper mold (40) side of the upper part, and the conveying member (S) does not get in the way of the molding work, and the molding can be performed without any problems in the same way as conventional sheet molding. I can do it.

In addition, if one foam sheet veneer (P) is simply placed on the conveying member (S), the heated and softened foam sheet veneer (P) will become flat due to thermal deformation during secondary foaming during the heating process. It may shrink in the direction, expand in the thickness direction, partially deform, or warp. Therefore, in carrying out the present invention, when simultaneously heating the foam sheet veneer (Pl) placed on the conveying member (S) is pressed in the thickness direction against expansion and deformation due to secondary foaming, Deformation and warping are eliminated, shrinkage in the plane direction is also prevented, and the foam sheet veneer (P) does not suffer from thermal deformation, and the outer edge of the foam sheet veneer (P) is strongly pulled to create a clamp. It is suitable because it can be conveyed in the same good flat state.In particular, by the above pressure, the softened foam sheet veneer (P) is pressed against the conveyance member (S) side and comes into close contact with it.
The foam sheet veneer (P) can be supplied to the molding process without being displaced or deformed during movement of the conveying member (S). In addition, by pressurizing the foam sheet veneer (P) and regulating secondary foaming, the thickness after two-dimensional @ can be freely adjusted, and the molding thickness of the molded product (H) can be accurately adjusted. This also has the effect of making the molding finish of the molded product (H) extremely good.

As a molding device, a conveying member (S) is installed instead of the conventional clamp mechanism, and a heating plate (30) is installed to press the foam sheet veneer CP) in the heating process.
It is sufficient to simply provide the following members. Therefore, by simplifying the cylindrical structure, which eliminates the need for a complex lamp structure, the effect of reducing equipment costs is significant. Moreover, the mold (40) (42)
Since the molding mechanism can be implemented using the same structure as the conventional one, the structure of the entire molding apparatus is not complicated and the molding efficiency is good.

As mentioned above, a molded product (H) made from a foam sheet veneer (P)
゛) can be easily and efficiently molded as a single item.
It has a variety of excellent effects, such as a good finish.

Experimental Example> In order to demonstrate the above-mentioned effects of the present invention, a molded article (H) was molded using a specific molding apparatus.

First, the molded product (H) has a diameter of 70 gm and a depth of 4 mm.
A cup-shaped container with a QI of 1 m is molded. Foam sheet veneer C
P) has a thickness of 1. (lllll, lff1360 #4 foamed polystyrene sheet was cut into a predetermined size and used, and the structure shown in Fig. 7 was used as a molding device. Also, as a conveying member (S), a glass fiber A woven sheet was impregnated with a fluororesin to form a sheet with a thickness of 300 μm, and a sheet with ventilation holes consisting of crosscuts having a width of 1 Qia was used.

The heating process was performed by placing a single foam sheet (P) on the conveying member (S) as described above, but the heating plate (30) (31)
For this purpose, we used aluminum metal with good thermal conductivity and a built-in cartridge heater, and set the heater temperature of the upper heating plate (30) to 140±5℃ and the lower heating plate (31) to 140±5℃.
I set the thermostat to 180±5℃ and heated it.Also, I heated the foam sheet (temporarily) using the heating plate (301).
The pressing force when pressurizing P) was set to 0.8 and 96.

The heating time was 5 seconds, and the foam sheet veneer (
The secondary foaming thickness of P) was 3.2 m1n.

Next, the molded product (
H) was molded, and the molding time was 3 seconds. The molded article (H) had a good finish, and the effect of this invention was verified. In particular, the width of the flange portion on the outer periphery of the molded product (H) was 3 to 4 cm, and no trimming was required and it was possible to use it as is. In addition, the difference between the diameter of the foam sheet veneer CP) before molding and the outer diameter of the molded product (H) after molding is about 0.4 ± 0.2 m1n, which hardly changes before and after molding and is stable. A good finish was obtained.

4゜ Drawing I! The illuminating explanatory drawings show an embodiment of the present invention, and FIG. 1 is an fX structure of the entire molding device. Structure diagram of modification example, No. 8
The figure is a structural diagram of yet another modification.

(1)...Piece storage section, (21...Transportation conveyor, (20)...Driving belt, (3)
... Heating section, (30) (31) ... Heating plate, (4) ... Molding section, (40) ...
・Upper mold, (41)...Vacuum suction hole, (42)・
...Lower mold, (43) ...Upper air outlet, (P) ...Foam sheet veneer, (S) ...
...Transportation parts.

Patent applicant: Sekisui Plastics Co., Ltd.
Attorney Hiroshi Kamei, Patent Attorney
Win 1W (1 other person> H, 4?154 Figure

Claims (1)

[Claims] 1.Heating and softening the thermoplastic resin foam sheet and then heat-forming it along the mold. Place the foam sheet on each individual molded product. Cut into boards and ventilate this foam sheet veneer Processing while placed on a conveying member with Transported from the heating process to the molding process, During the process, the foam sheet veneer is heated and softened. After that, it can be thermoformed in the molding process. A method for forming a foam sheet, characterized by: 2. In the heating process, the foam sheet veneer is At the same time as heating softens, it also prevents heat generation. To counter the secondary foaming of the foam sheet, The above patent claim applies pressure to the sheet in the thickness direction. Method of forming a foam sheet according to item 1 of the scope of Law. 3. In the heating process, the conveying member and Press the heating plate on both the top and bottom of the foam sheet veneer. to heat and soften the foam sheet veneer. At the same time, the above patent application applies pressure in the thickness direction. Molding of foam sheet as described in item 1 of the scope of demand Method. 4. In the heating process, the foam sheet veneer The heating temperature for the top side is higher than that of the foaming sheet. Increase the heating temperature for the bottom side of the veneer. According to claim 1 above, Method of forming foam sheets. 5. Compatible with the shape of the molded product in the molding process from the concave upper mold and the almost flat lower mold. A foam sheet is placed in the middle of a pair of molds. Place the veneer and transport material, and The upper and lower outer edges of the veneer and conveyance member After being sandwiched between molds, the foam sheet veneer is The above patent for thermoforming along a concave upper mold Formation of the foam sheet according to claim 1 shape method.