JPS612527A - Thermoformer - Google Patents

Abstract

PURPOSE:To make the thickness of the molded sheet uniform and to minimize the amount of stretch when molding is effected, by allowing clamp frames for clamping a sheetlike material to be bent approximately along the shape of the molding surface of a mold. CONSTITUTION:The four side parts of a sheetlike material 23 are placed on a seat 24, and the sheetlike material 23 is secured to clamp frames 11 by toggle clamps 26. The sheetlike material 23 of a thermoplastic resin is heated and softened, and the upper surface of the mold 1 is lifted with it contact with the undersurface of the sheetlike material 23. At the same time, the clamp frames 11 are bent at hinges 22, and wheels 10 are moved inward along a rail 9. When the mold 1 is further lifted to reach a prescribed position, right and left frame plates 13, 14 of the clamp frames 11 are bent approximately at a right angle with the central frame plate 12, the sheetlike material 23 comes in contact with the whole effective molding surface of the mold 1 and is pushed up by ridge lines 31 to secure vacuum sealing, and it is molded with it firm contact with the molding surface of the mold. As the sheetlike material 23 is molded in this manner, the effective molded part is hardly stretched and the thickness of the molded item is made uniform.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a thermoforming apparatus, and more specifically, a clamp frame that clamps a sheet-like material based on a thermoplastic resin to be molded, The present invention relates to a thermoforming device that can be bent along a surface shape.

Conventional technology For example, a seat back panel 50 for a vehicle shown in FIG.
In this method, a sheet-like material based on thermoplastic resin is clamped between integral flat clamp frames and thermoformed to produce a box-shaped molded product 23a as shown in FIG. The product was cut along the line shown. This seat back panel is a U-shaped product with a U-shaped cross section consisting of three faces 51, 52, 53, each of which is bent at a right angle on the left and right sides of one plane 51, and both sides 52, 53 are the sides of the seat 54. The central surface 51 is located on the back of the seat and a net 55 etc. is attached to it for the convenience of the rear passengers, and the upper and lower surfaces are not required as they fit into the seat 54.

The problem that Akira is trying to solve is that when a U-shaped product such as the seat back panel mentioned above is manufactured using a conventional thermoforming machine equipped with an integral planar clamp frame, the sheet material for molding is A large elongation of 1.5 to 4.0 times is required at the temperature of the material to be molded. Therefore, it is difficult to mold a sheet-like material made by laminating a thermoplastic resin sheet with a woven fabric for surface decoration with low elongation. It was difficult or impossible. Furthermore, the thermoplastic resin sheet that serves as the base material of the sheet-like material to be collapsed is also stretched non-uniformly during molding. For example, Figure 4 is a cross-sectional view of a box-shaped molded product made by the straight molding method using a female mold.
The figure is a cross-sectional view of a box-formed article made by drape-molding with a male mold, in which the corner portions 56 of the bottom of the box are particularly thin in the former case, and the side walls 52, 53 in the latter case are thinner.

Therefore, the thickness of the base material of the sheet material for molding is set to be larger than necessary, taking into consideration in advance the mechanical strength of each part required for the product and the reduction in thickness after molding. Furthermore, a molded product made of a sheet-like material in which a surface-decorating woven fabric made of stretchy fibers is laminated to a thermoplastic resin sheet on the outer side of the molded product is cut along the two-dot chain line in Figure 3. When the product is made into a product, the woven fabric that has been stretched during molding shrinks, so the side surfaces 52 and 53 of the product tend to open in a V-shape with respect to the center surface 51. In the case of seat back panels, this deformation is serious. It was a serious defect.

Measures to Solve the Problems This invention was made by focusing on the problems of the conventional art, and it involves bending the clamp frame that clamps the sheet-like material to be molded almost along the shape of the molding surface of the mold. By making this possible, the various problems mentioned above are solved.

The sheet-like material fixed by the clamp frame with a soft jaw and the mold are brought close to each other, and the clamp frame is bent along the molding surface of the mold, thereby deforming the sheet-like material along the molding surface. Therefore, a uniform force acts on the entire sheet material that hits the molding surface during molding, making it possible to make the thickness of the molding surface uniform and to keep the amount of stretching during molding to a small level.

Embodiment FIG. 1 is a diagram that best represents the features of the present invention, and is a sectional view of a main part of a thermoforming apparatus according to the present invention.

A mold 1 is hermetically fixed to the upper surface of a table 3 which can be raised and lowered by movement of a piston 2 of a fluid pressure cylinder. A large number of small-diameter exhaust holes 4 are bored in the molding surface 1a of the mold 1 (see also FIG. 11). It is connected to a vacuum pump (not shown) through the vacuum pump. Above the mold 1, an upper heater 7 and a lower heater 8 are installed so that they can be moved to predetermined positions when heating the sheet material.

As shown in FIG. 6, there is a heater fixed to the frame (not shown) of the thermoforming apparatus main body in the gap between the upper heater 7 and the lower heater 8, which are located above the mold 1 and are positioned during heating. Two rails 9 are arranged laterally. A clamp frame 11 with wheels 10 attached to its four corners is installed so as to be movable on this rail 9h.

As shown in FIG. 6, the clamp frame 11
It is cut into a pair of central frame plates] 2 in a direction perpendicular to the axle 10a of the wheel, and U-shaped left and right frame plates 13 and 14, each of which is rotated by a hinge 22, the details of which are shown in FIG. movably coupled.

These left and right frame plates 13 and 14 are not bent upward by a stopper (not shown) with respect to the central frame plate 12, but are bent downward to a predetermined angle freely. On the inner surface of each frame plate 12, 13° 14 is a pedestal 2 on which the end of the sheet material 23 (Fig. 1) to be formed is placed.
4 are provided respectively, and the top surface of the pedestal 24 is
When the clamp frame 11 is in its bending position, it is on substantially the same plane as the plane containing the central axis of the pin 22a of each hinge 22 (see FIG. 9).

As shown in FIG. 1, each frame plate 12 of the clamp frame 11,
A downward holding type toggle clamp 26 (not shown in FIGS. 6 and 7) as shown in FIGS. 8 and 9 is fixed to a key point of each arm 13 and 14.

This toggle clamp 26 pushes the push plate 28 downward through its presser 27, and firmly clamps the end of the sheet material 23 inserted between the base 24 and the push plate 28 during molding. Note that, like the corresponding pedestal 24, the push plate 28 is also cut at respective positions corresponding to the bent portions of the clamp frame 11.

During thermoforming, the clamp frame 11 is bent at the center axis of the pin of the hinge 22, and each pedestal 24 is formed between the molding surface 1a of the mold 1 and the non-effective molding side surface 1b (see also FIG. 11), as shown in FIG. Since it enters inside the ridge line 31, the inner diameter between the opposing pedestals 24 in the vertical direction of the clamp frame 11 (in the direction perpendicular to the plane of paper in FIG.
50 mm larger, and the length of each frame plate 12, 13.14 is such that when the clamp frame 11 is bent, the sheet-like material mounting surface of the base of each frame plate 12, 13.14 is on the inside of the ridge line 31.
50 nn. Therefore, the lower part of the mold 1 is designed so that the frame plates 13 and 14 penetrate into the interior from the downward extension of the ridge line 31.

As described below, in the thermoforming apparatus of the present invention, the clamp frame 11 that clamps the sheet-like material 23 to be molded can be bent along the shape of the molding surface of the mold 1, so that it is possible to bend the clamp frame 11 in accordance with the shape of the molding surface of the mold 1. It is possible to solve the problems when molding a molded product with a U-shaped cross section. The operation of the illustrated thermoforming apparatus will be explained below according to the processing order. First, the clamp frame 11 is stretched into a flat shape and placed at predetermined positions on the rail 9), and the pedestal 2 of each frame plate 12, 13° 14
The four circumferential ends of the sheet-like material 23 to be formed into four sheets are placed, and the sheet-like material 23 is fixed to the clamp frame 11 with the toggle clamp 26 via the push plate 28. At this time, the stoppers 30 provided on the rail 9 in four different directions come into contact with the axle IO, and the clamp frame 11 is installed at a predetermined position on the rail 9F.

Next, the upper heater 7 and the lower heater 8 are moved to heat and soften the thermoplastic resin sheet of the sheet material 23, and then the heaters 7.8 are moved back and the mold 1 is raised while exhausting air from the exhaust pipe 6. let By the time the mold 1 reaches a predetermined height, the L side of the mold 1 has reached the sheet-like material 2.
3, and then lift this material 23, and as a result, the clamp frame 11 is bent at the hinge 22, and the axle 1
0 moves inside rail 9hi. When the mold 1 further rises and reaches the predetermined position shown in FIG.
The left and right frame plates 13 and 14 of the frame plate 1 are bent almost at right angles with respect to the central frame plate 12, and the sheet material 23 contacts the entire effective molding surface of the mold 1, and as shown in FIG. The sheet material 23 is pushed up at the ridge line 31 and vacuum sealed, and the sheet material 23 is molded in close contact with the molding surface of the mold 1. After the molded product has cooled, the toggle clamp 26 is opened, the push plate 28 is removed, the molded product is taken out, and the clamp frame 11 is returned to its original flat state.

In this way, the sheet-like material 23 is molded with its end portions held between the clamp frame 11 at a position along the molding surface of the mold, so that the effective molding portion is hardly stretched and the cross-section is reduced. It is molded into a letter-shaped molded product, and the thickness of the completed molded product is uniform throughout.

Next, an example of forming a seat back panel for a vehicle using the thermoforming apparatus of the present invention will be described below.

The sheet-like material 23 is a lamination of a tricot woven fabric as a skin layer for surface decoration, a highly foamed polyethylene sheet as an intermediate cushion layer, and a polypropylene sheet as a base layer.

The sheet-like material 23 is cut into a molding material that is 5% larger than the length in the vertical direction of the mold 1 and the soot length in the lateral direction of the molding surface 1a. Fixed to.

Next, the sheet material 23 is heated by the upper heater 7 and the lower heater 8, but since the skin layer is a woven fabric, the amount of heat applied to the skin layer side may be half of the amount of heat applied to the base material layer side. Further, the amount of heat applied to the base material layer side can be reduced to two-thirds or less compared to the conventional molding method using an integral planar clamp frame. This is because the amount of stretching of the base material layer during molding remains smaller than conventionally.

When the upper molding surface of the mold 1 comes into contact with the lower surface of the softened sheet-like material 23 and the mold 1 continues to rise, the sheet-like material 23 lifts the clamp frame 11, but the skin layer of the sheet-like material 23 The woven fabric does not cause the base layer to be excessively stretched or cut. Molding die 1 is the 8th
When the highest position shown in the figure is reached, the left and right frame plates 13.1
4 and slightly floating from the rail 9, the wheels automatically move to the supported parts of the mold 1 due to their weight, and the left and right frame plates 13 and 14 of the sheet material 23 are moved. The portion fixed to is also molded in contact with the side molding surface of the mold 1.

In the seat back panel formed in this way, the thickness of the base material is more uniform over the entire surface than before.
There is no V-shaped deformation in thermal cycle tests, there is no digging into the texture of the woven fabric of the highly foamed polyethylene sheet on curved surfaces, and the product can be manufactured without reducing the decorative properties, cushioning properties, and rigidity of the material before molding. I was able to do that. Furthermore, if a mold having a protruding molding surface 1a and non-molding surfaces 1b on both sides of the molding die is used, the completed molded product will already have a U-shape.
(Figure 3) It is no longer necessary to cut out the upper and lower parts significantly, and waste of material can be reduced. This fact and material 2
By being able to reduce the amount of stretching in step 3, the developed area of the product was approximately 90% of the area of the sheet material 23 used. 5 when using a conventional integral flat clamp frame
It was 0% or less.

As another example, as shown in FIG. 10, a pair of frame plate moving cylinders 32 fixed to the frame (not shown) of the thermoforming apparatus main body is used to move the left and right frame plates 13 and 14 in the final stage of molding. The sheet-like material 23 can be pressed into the supported portion of the mold 1 to bring it into close contact with the vertical side surface of the molding surface 18 of the mold. Note that this method is particularly effective when the side surface of the molding surface is undercut.

Further, the heating of the sheet material 23 and the removal of the molded product from the clamp frame 11 do not necessarily need to be performed above the mold 1. For example, the clamp frame 11 is placed on the rail 9.
Prepare a plurality of sheets of material 23, heat the sheet material 23 at a location away from the mold 1, and then insert the material into the clamp frame 1 together with the sheet material 23.
1 is caused to run on the rail 9 and brought above the mold 1, and then stopped by the stopper 30, thereby making it possible to improve the molding efficiency. Similarly, it is also possible to move the molded clamp frame 11 on the rails 9 and remove the molded product at a location away from the mold.

The number of bending points of the clamp frame 11 may be set as appropriate depending on the shape of the molded product. For example, when the molding surface 1a has a large radius of curvature between the upper surface and its left and right side surfaces, the eighth
If the clamp frame has only four bending points as in the embodiment shown in the figure, in order to fit the entire sheet-like material attachment surface of the pedestal 24 inside the ridge line 31, the pedestal 24 must be placed inside the ridge line 31. It is necessary to make a large penetration, which increases material waste. Therefore, in such a case, by increasing the bending points of the clamp frame 11, the sheet material attachment surface of the frame plate pedestal 24 is brought closer to the ridge line 31 of the mold 1, thereby reducing waste of the sheet material 23. It is advantageous to do so. Furthermore, by increasing the number of refraction points, it is possible to perform molding even if the effective molding side surface of the mold 1 is undercut. The number of bending points on opposing frame plates may be different.

As shown in FIG. 11, if a clamp base 34 is provided where the bottom of the clamp frame 11 is in contact with the non-effective side surface 1b of the mold l, the clamp frame 11 can be attached to the mold 1 when using a thin or soft molding material. It is possible to prevent the molding material from being excessively stretched or cut by not following the rise.

Furthermore, as shown in FIG. 11, if the mold 1 is divided into a part 1c having a molding surface 1a and a part 1d inside thereof, and these parts are removably connected, it is possible to prevent damage to the molding surface 1a. It is easy to replace when changing the pattern of the molding surface 1a.

In the above embodiment, the case where the mold has an upwardly convex shape has been described, but the present invention can be applied even if the mold has an upwardly concave shape. In this case, for example, the hinge 22 of the clamp frame 11 is a hinge with a clutch, and when the clamp frame reaches a certain position in the mold, the clutch of the hinge is released and the clamp frame is bent downward, and the left and right frames are 13 and 14 are pushed inward by the cylinder 32 for moving the frame plate, and the sheet material is brought into contact with the concave molding surface. In this case, it is advantageous if the frame plates 13, 14 are subsequently moved slightly outwards by means of the cylinder 32, in order to bring the sheet-like material into close contact with the vertical flanks of the concave molding surface.

The thermoforming device of the present invention can bend the clamp frame that clamps the sheet-like material to be molded almost along the shape of the molding surface of the mold, so it can be used to When molding a product with a U-shaped cross section consisting of three sides bent at almost right angles, the sheet material is rarely stretched or expanded during molding, so the product The thickness is almost the same as the thickness before molding, and it is uniform and maintains the rigidity before molding, making it possible to use a decorative woven fabric with low elongation as the outer layer, and the cushioning layer also prevents a decrease in elasticity. Furthermore, it is possible to increase the production rate of the sheet material to be molded, and it is possible to easily remove the molded product from the mold even if there is an undercut on the side surface of the molding surface. .

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a thermoforming apparatus according to the present invention, Fig. 2 is a perspective view showing a practical example of a sheet pack panel, Fig. 3 is a perspective view of a molded product formed by a conventional method, and Fig. 4 and the fifth
6 is a perspective view of the clamp frame of the present invention, FIG. 7 is a partially enlarged view of FIG. 6, and FIG. 8 is a sectional view of a molded product molded by a conventional method. A side view showing the positions of the mold and the clamp frame, Fig. 9 is a sectional view showing the state in which the sheet material is clamped, Fig. 10 is a perspective view of the clamp frame with the cylinder attached, and Fig. 11 is a cross-sectional view showing the state in which the sheet material is clamped. It is a perspective view showing a mold of an example. 1... Molding mold 11... Clamp frame 23... Sheet material Fig. 2 5z Fig. 4 Fig. 3 Fig. 5

Claims (1)

[Claims] 1. A thermoforming device characterized in that a clamp frame that clamps a sheet material to be molded can be bent substantially along the shape of a molding surface of a mold.