Method of forming bent shaped resin molded article

Abstract

To prevent wrinkling at a bent portion of a resin molded article in a method of folding a flat resin sheet-like member 1 on a bent shaped frame to form the resin sheet-like member into the bent shaped resin molded article.SOLUTION: An outer peripheral edge of a flat resin sheet-like member is clamped by a pair of bendably formed outer frame members 2. Each of a pair of opposing both side edges which are not bent, of the resin sheet-like member is gripped by a clamping member 3L or 3R. While the resin sheet-like member is heated, the pair of outer frame members that have clamped the resin sheet-like member are placed on a surface of a mold base 20 having a shape formed by bending a flat plate in one direction so that a pair of bendable side edges of the pair of outer frame members can be bent along a bending shape of the mold base. Along the bent surface of the mold base, the pair of outer frame members are bent with the resin sheet-like member. The resin sheet-like member is pulled by the clamping member outward of each side. The resin sheet-like member is returned to the normal temperature, and thereafter, the bent resin sheet-like member is removed from the outer frame members.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a method for forming a resin molded product, and more particularly to a method for forming a resin molded product having a bent shape.

Background Art

[0002] Various configurations have been proposed for the method of forming a resin molded product. For example, in Patent Document 1, as a method for forming a bent resin molded product with a decorative sheet laminated thereon, a decorative sheet of a thin film laminated on both sides of the molded product is bent, and a molten resin is filled between the bent decorative sheets to obtain a bent resin molded product. The method is described.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] If the thickness of the resin molded product having a bent shape is not so thick, it is possible to form a flat resin sheet-like member by bending it on a mold having a bent shape. The method of bending a flat resin sheet-like member is simpler in equipment than a method of injecting and casting molten resin into a mold having a bent shape, and simply heating and softening the resin sheet-like member, bending and deforming it, and cooling it. Therefore, it is advantageous in terms of production lead time, such as short molding time. However, when a flat resin sheet-like member is bent to form a resin molded product having a bent shape, the inner region of the bent portion can be compressed. Therefore, when the thickness of the resin sheet-like member increases, there may be excess meat, and wrinkles may occur on the surface of the bent portion, which may impair the appearance of the molded product. Therefore, in the method of bending a flat resin sheet-like member, it is advantageous to have a novel configuration that does not cause wrinkles.

[0005] In view of the above circumstances, the main problem of the present invention is, in a method of forming a resin molded product having a bent shape by bending a flat resin sheet-like member on a frame having a bent shape, to prevent wrinkles from occurring at the bent portion of the resin molded product.

Means for Solving the Problem

[0006] According to the present invention, the above problem is a method of forming a resin molded product having a bent shape, preparing a pair of outer frame members configured to sandwich the outer peripheral edge of a flat resin sheet-like member, the pair of opposing edges of which are formed to be bendable in a direction intersecting the surface direction of the flat resin sheet-like member to be sandwiched; clamping the outer peripheral edge of the flat resin sheet-like member with the pair of outer frame members; grasping clamp members on both edges of the resin sheet-like member held by the pair of opposing edges that are not bent in the outer frame member; heating the resin sheet-like member; placing the pair of outer frame members sandwiching the resin sheet-like member on the surface of a mold base having a shape bent in one direction, such that the pair of bendable edges thereof can be bent along the bent shape of the mold base, and bending the pair of outer frame members together with the resin sheet-like member along the bent surface of the mold base; pulling the resin sheet-like member outward on each side with the clamp members; returning the resin sheet-like member to room temperature; removing the resin sheet-like member from the outer frame members; and a method including is achieved.

[0007] In the above configuration, the "resin sheet-like member" may be a thermoplastic resin material commonly used in this field, for example, a polycarbonate resin, an acrylic resin, or the like. Further, the resin sheet-like member may have any dimensions, typically having a thickness of 4 to 6 mm and longitudinal and lateral dimensions of about 1500 mm × 1000 mm to 3000 mm × 2000 mm, but is not limited thereto. The "outer frame member", "clamp member", and "mold base" may each be formed of any material (metal, resin) that can be used to heat and bend the resin sheet-like member. The heating of the resin sheet-like member is usually carried out by the radiant heat of any heater or the like until the resin sheet-like member reaches a temperature at which no defect occurs in its surface properties from its glass transition point. The step of returning the heated resin sheet-like member to room temperature may be achieved by stopping the heating of the heater, or a process of cooling the resin sheet-like member heated in any manner may be carried out.

[0008] According to the above configuration, when the resin sheet-like member is heated and bent along its bent shape on a mold having a shape in which a flat plate is bent in one direction while being sandwiched between a pair of outer frame members, not only that, but before being returned to room temperature, the pair of edges that are not bent are pulled outward in a direction away from each other, that is, pulled outward by the clamp member. As a result, the inner region of the bent portion of the resin sheet-like member is also pulled outward, so that there is no excess material, and wrinkles can be prevented from forming in the molded product.

[0009] In the above configuration, a vacuum forming method may be used when the resin sheet-like member is bent and deformed. The bending angle of the resin sheet-like member may be arbitrarily set according to the shape required for the molded product. The pulling of the resin sheet-like member by the clamp member may be achieved by the clamp member bending both edges of the resin sheet member in any direction with respect to its surface.

Effects of the Invention

[0010] Thus, according to the present invention, in a method of forming a resin molded product having a bent shape by bending a flat resin sheet-like member, it is possible to prevent the formation of wrinkles in the bent portion of the resin sheet-like member. The method of the present invention is relatively simple because it only needs to grip both edges of the resin sheet-like member that are not bent with a clamp member and pull them after bending, and is advantageous in that it does not require a large-scale configuration. The position gripped by the clamp member is away from the portion of the resin sheet-like member to be bent, and may be arbitrarily adjusted to the timing of pulling the resin sheet-like member.

[0011] Other objects and advantages of the present invention will become apparent from the following description of the preferred embodiments of the present invention.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Description of Reference Numerals

[0013] 1... Resin sheet-like member, 2... Outer frame member, 2UL, UR... Upper outer frame members, 2BL, BR... Lower outer frame members, 3L, 3R... Clamp members, 4U, 4B, 5L, 5R... Hinges, 10... Heater, 20... Mold base, 21... Bent portion of the mold base

Best Mode for Carrying Out the Invention

[0014] Formation of a resin molded product with a bent shape by bending a resin sheet member The resin molded product having a bent shape can be formed by various methods. If the thickness of the resin molded product is not so thick, it is possible to bend the flat resin sheet-like member 1 as depicted in Fig. 4(A) to form a resin molded product having a bent shape as depicted in Fig. 4(B). In this case, since it is only necessary to heat the flat resin sheet-like member 1 above its glass transition point and bend it on a bent-shaped mold, large-scale equipment is not required, which is advantageous in that the processing time is relatively short.

[0015] However, as depicted in Fig. 4(C), when simply bending a flat resin sheet-like member from both edges (arrow a), the outer surface thereof is stretched (arrow b), and the inner surface thereof is compressed (arrow c). Thus, when the resin sheet-like member reaches a certain thickness, inside the bending portion O, there will be excess material forming wrinkles, which will damage the appearance of the molded product. Therefore, in the present embodiment, while bending the flat resin sheet-like member, a pair of non-bent edges of the resin sheet-like member are pulled in a direction away from each other, eliminating the compression of the material inside the bending portion O and preventing the formation of wrinkles.

[0016] Configuration of an outer frame member In the present embodiment, the outer peripheral edge of the flat resin sheet-like member is clamped by a pair of outer frame members, and in this state, the outer frame members are bent on a bending-shaped mold while the resin sheet-like member is bent. Figs. 1(A) to (C) schematically show the outer frame members used at that time. Referring to the figure, the outer frame member 2 is composed of upper outer frame members 2UL, 2UR that clamp the outer peripheral edge of the flat resin sheet-like member from both sides and lower outer frame members 2BL, 2BR. The upper outer frame members 2UL, 2UR and the lower outer frame members 2BL, 2BR are each divided into two members, and the two members of each are connected by hinges 4U, 4B. Thus, as shown in Fig. 1(C), the outer frame member 2 is configured to be bendable in a direction intersecting the surface direction in the flat state at one of the opposing edges. Further, in the outer frame member 2 in the present embodiment, at a pair of non-bent edges of the lower outer frame members 2BL, 2BR (the left and right ends in the figure), clamp members 3L, 3R that grip the outer peripheral edge of the resin sheet-like member are attached via hinges 5L, 5R, and the clamp members 3L, 3R are configured to be further bendable with respect to the lower outer frame members 2BL, 2BR. With such a configuration, as will be described later, the non-bent both edges of the resin sheet-like member bent on the mold base are pulled in a direction away from each other, the resin sheet-like member is stretched, and the formation of wrinkles is prevented.

[0017] Bending process of a resin sheet-like member In the bending process (forming a resin molded product with a bent shape) of the resin sheet-like member according to this embodiment, first, as depicted in FIGS. 2(A) and (B), a flat resin sheet-like member 1 is sandwiched between the upper outer frame members 2UL and 2UR and the lower outer frame members 2BL and 2BR of the outer frame member 2 described above. At this time, both edges of the resin sheet-like member 1 on the non-bent edge side of the outer frame member 2 extend beyond the outer frame member 2 respectively and are gripped by the clamp members 3L and 3R attached to each of the non-bent edges of the outer frame member 2. The resin sheet-like member may be formed from a thermoplastic resin material such as a polycarbonate resin or an acrylic resin as already mentioned. Typically, it has a thickness of 4 to 6 mm and may have longitudinal and lateral dimensions of about 1500 mm × 1000 mm to 3000 mm × 2000 mm.

[0018] Then, the outer frame member 2 sandwiching the resin sheet-like member 1 with both edges gripped by the clamp members 3L and 3R is placed on the mold base 20 having a bent shape in a state where the resin sheet-like member 1 is heated by the heater 10 to a temperature equal to or higher than its glass transition point and at which no surface defects occur. Here, the heating of the resin sheet-like member 1 may typically be performed non-contact by the radiant heat of the heater 10. Also, when placing the outer frame member 2 on the mold base 20, the connection part between the 2UL and 2UR of the upper outer frame member and the connection part between the 2BL and 2BR of the lower outer frame member are aligned with the bent part 21 on the mold base 20, and the outer frame member 2 is placed so that it can be bent along the bent shape of the mold base 20 (note that the bent shape of the mold base 20 may be not only a convex shape as shown in the figure but also a concave shape). In that state, as shown in FIG. 2(D), the outer frame member 2 bends along the bent shape of the mold base 20, and the resin sheet-like member 1 is bent. Such a bending process may be performed by a process of bringing the resin sheet-like member 1 into close contact with the shape of the mold base in a space depressurized according to the vacuum forming method.

[0019] Next, as shown in Fig. 3(A), the upper outer frame members 2UL and 2UR are removed from the resin sheet-like member 1 (arrow X). In this state, as shown in Fig. 3(B), the clamp members 3L and 3R are bent with respect to the lower outer frame members 2BL and 2BR, respectively (arrow Y). As a result, the resin sheet-like member 1 is extended in the direction of the clamp members 3L and 3R, that is, in the direction in which the unbent edges are separated from each other (arrow e). Thereby, the compression of the flesh inside the bent portion is eliminated, and the formation of wrinkles is prevented. The traction of the resin sheet-like member 1 at this time may be performed so that its area is extended by about 10%.

[0020] Thereafter, by stopping the heating of the heater 10 or further cooling the mold base 20, the resin sheet-like member 1 is returned to room temperature in the bent state and removed from the lower outer frame members 2BL and 2BR and the clamp members 3L and 3R, and the resin molded product 1 having a bent shape is completed (Fig. 3(C)).

[0021] In addition, the traction by the clamp members 3L and 3R, as shown in Fig. 3(B), may be performed by bending the clamp members 3L and 3R with respect to the lower outer frame members 2BL and 2BR, or as shown in Fig. 3(D), by moving the clamp members 3L and 3R outward in the extending direction of the lower outer frame members 2BL and 2BR. Further, the clamp members 3L and 3R may be attached to the upper outer frame members 2UL and 2UR. In that case, the resin sheet-like member 1 may be extended by bending the clamp members 3L and 3R with respect to the upper outer frame members 2UL and 2UR.

[0022] According to the method of the above-described embodiment, it is only necessary to grip both unbent edges of the resin sheet-like member with the clamp members and perform traction after bending, so it is relatively simple and advantageous in that it does not require a large-scale configuration.

[0023] The above description has been made in connection with the embodiments of the present invention. However, many modifications and changes are easily possible for those skilled in the art, and the present invention is not limited only to the embodiments illustrated above, and it will be apparent that the present invention can be applied to various devices without departing from the concept of the present invention.

Claims

【Claim 1】 A method for forming a resin molded article having a bent shape, comprising: preparing a pair of outer frame members configured to sandwich the outer peripheral edge of a flat resin sheet-like member, wherein a pair of opposing edges of the outer frame members are formed to be bendable in a direction intersecting the surface direction of the flat resin sheet-like member to be sandwiched; sandwiching the outer peripheral edge of the flat resin sheet-like member with the pair of outer frame members; gripping clamp members on both edges of the resin sheet-like member sandwiched by the pair of opposing edges of the outer frame members that are not bent; heating the resin sheet-like member; placing the pair of outer frame members sandwiching the resin sheet-like member on the surface of a mold base having a shape bent in one direction, such that the pair of bendable edges can be bent along the bent shape of the mold base, and bending the pair of outer frame members together with the resin sheet-like member along the bent surface of the mold base; pulling the resin sheet-like member outward on each side with the clamp members; returning the resin sheet-like member to room temperature; and removing the resin sheet-like member from the outer frame members. A method including the above steps.

Images