JP7198994B2 - Molded body manufacturing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a molded article having a skin material, and more particularly to a novel method for producing a molded article in which holes are made in a mold.

2. Description of the Related Art Conventionally, a molded body made of a resin sheet having a single wall structure has been used as a molded body such as an automobile interior member. For example, in Patent Document 1, a resin sheet is used for an automobile door trim.

Japanese Patent No. 4297738

By the way, there is a case where a skin sheet is formed on a molded body having a single wall structure. done.

Here, there are cases where the molded body needs to be perforated, and normally, after the molded body is taken out of the mold, the perforation is performed as a post-processing. However, drilling holes in post-processing causes an increase in the number of man-hours, which is not preferable in terms of productivity. In addition, in order to make holes in the post-processing, equipment investment is also required, such as the need for a press machine for making holes separately.

In addition, particularly in a molded product having a skin material, it is not easy to make holes, and in the case of making holes by knife or punching, there is a problem that the inner layer is exposed on the cut surface and the molding accuracy is lowered.

The present invention has been proposed in view of such conventional circumstances, and an object of the present invention is to provide a method for manufacturing a molded body that enables efficient drilling without increasing the number of facilities and man-hours. .

In order to achieve the above object, the method for producing a molded article of the present invention is a method for producing a molded article, in which a molded article having a skin material is molded in a mold and holes are formed in the molded article. A pair of divided molds are used, one mold is provided with a projecting member, and the other mold is formed with an opening for receiving the projecting member, and the tip surface of the projecting member is retracted. At this position, it constitutes a part of the molding surface of the one mold, and when molding the molded product, the projecting member is projected from the side opposite to the skin material in the mold to make a hole. It is characterized by

The basic idea of the present invention is to punch holes in a mold, and by optimizing the protruding member, it is possible to punch holes efficiently and accurately.

EFFECTS OF THE INVENTION According to the present invention, it is possible to efficiently perforate a molded body having a skin material without requiring separate equipment. In particular, according to the present invention, when the molded body is taken out after the completion of molding, the drilling process is completed, so that the molding process can be greatly streamlined.

It is a schematic sectional drawing which shows an example of the molded object manufactured. FIG. 2 is a view showing an example of a molding machine for molding a molded body in which a skin sheet and a foamed resin sheet are integrated; FIG. 2 is a schematic cross-sectional view showing the molding process of a molded body, where (A) is a resin sheet and skin sheet supply process, (B) is a mold clamping process, and (C) is a vacuum suction to shape the resin sheet into a cavity shape. Each step is shown. FIG. 4 is an enlarged view showing the vicinity of a burr cutting position of a molded body having a skin material, (A) is a schematic cross-sectional view showing a burr cooling process, and (B) is a schematic cross-sectional view showing a projecting process of a projecting member. FIG. 3 is an enlarged view showing the vicinity of the burr cutting position of a molded body having a skin material, (A) is a schematic cross-sectional view showing the step of cooling the burrs from the surface opposite to the skin material, and (B) is the skin material. FIG. 10 is a schematic cross-sectional view showing a step of projecting the projecting member from the surface opposite to the . It is a diagram showing a hole making process, (A) is a resin sheet injection process, (B) is a mold clamping process, (C) is a forming process, (D) is a hole making process, and (E) is a mold opening process. indicates It is a photograph showing a hole opening state, (A) and (B) are when the protrusion member is protruded from the skin material side and the hole is formed, and (C) and (D) are when the protrusion member is protruded from the resin sheet side. This is the case when perforation is performed. It is a diagram schematically showing a hole opening state, (A) is a case in which the protrusion member is protruded from the skin material side to form a hole, and (B) is a case in which the protrusion member is protruded from the resin sheet side to form a hole. is the case.

Hereinafter, an embodiment of a method for manufacturing a molded article to which the present invention is applied will be described in detail with reference to the drawings.

As shown in FIG. 1, the molded body 1 molded in this embodiment is obtained by laminating and integrating a so-called carpet-like skin sheet 3 on the surface of a foamed resin sheet 2. The skin sheet 3 side is the design surface. For example, it is used as a trim material for vehicles.

The thermoplastic resin used for the foamed resin sheet 2 is arbitrary, and examples thereof include polyolefins. Examples of polyolefins include low-density polyethylene, linear low-density polyethylene, high-density polyethylene, polypropylene, and ethylene-propylene. Examples include copolymers and mixtures thereof.

The foamed resin sheet 2 is a single-layer resin sheet, but the thickness of the foamed resin sheet 2 is expanded by vacuum suction in the mold during molding, and thus the foamed resin sheet 2 is molded so as to be in contact with the mold. After cooling, it is in a more dense state (lower expansion ratio) than the central portion (a state in which the front and back surfaces have skin layers). Therefore, it has a structure similar to a so-called double wall structure, and has high rigidity even with a single layer.

The skin sheet 3 constitutes the design surface as described above, and is made of a so-called carpet material, non-woven fabric, or the like. The skin sheet 3 is molded over the foamed resin sheet 2 in a molten state, and integrated with the foamed resin sheet 2 in a heat-sealed state.

The molded body 1 described above is molded, for example, by a molding machine as shown in FIG. FIG. 2 shows an example of a molding machine for molding the molded body 1. The molding machine 10 includes a resin supply device 20, a T-die 18, and molds 30 and 40. As shown in FIG. The resin supply device 20 includes a hopper 12 , an extruder 13 , an injector 16 and an accumulator 17 . The extruder 13 and the accumulator 17 are connected via a connecting pipe 25 . The accumulator 17 and the T-die 18 are connected via a connecting pipe 27 .

The hopper 12 is used to charge the raw material resin 11 into the cylinder 13 a of the extruder 13 . Although the form of the raw material resin 11 is not particularly limited, it is usually in the form of pellets. The raw material resin 11 is fed from the hopper 12 into the cylinder 13a, and then heated in the cylinder 13a to be melted into a molten resin. Further, it is conveyed toward the tip of the cylinder 13a by the rotation of the screw arranged in the cylinder 13a. The screw is arranged in the cylinder 13a, and conveys the molten resin while kneading it by its rotation. A gear device is provided at the proximal end of the screw, and the screw is rotationally driven by the gear device. The number of screws arranged in the cylinder 13a may be one or two or more.

The cylinder 13a is provided with an injector 16 for injecting a foaming agent into the cylinder 13a. If the raw material resin 11 is not foamed, the injector 16 can be omitted. The blowing agent injected from the injector 16 includes physical blowing agents, chemical blowing agents, and mixtures thereof, but physical blowing agents are preferred. As physical blowing agents, inorganic physical blowing agents such as air, carbon dioxide gas, nitrogen gas, and water, organic physical blowing agents such as butane, pentane, hexane, dichloromethane, and dichloroethane, and supercritical fluids thereof are used. be able to. As the supercritical fluid, it is preferable to use carbon dioxide, nitrogen, or the like. Nitrogen has a critical temperature of −149.1° C. and a critical pressure of 3.4 MPa or higher, and carbon dioxide has a critical temperature of 31° C. and a critical pressure of 3.4 MPa. It is obtained by making it 7.4 MPa or more. Chemical foaming agents include those that generate carbon dioxide through a chemical reaction between an acid (eg, citric acid or its salt) and a base (eg, sodium bicarbonate). The chemical blowing agent may be injected from hopper 12 instead of injected from injector 16 .

The molten resin 11 a to which a foaming agent is added or not is extruded from the resin extrusion port of the cylinder 13 a and injected into the accumulator 17 through the connecting pipe 25 . The accumulator 17 has a cylinder 17a and a piston 17b slidable inside the cylinder 17a, and the molten resin 11a can be stored in the cylinder 17a. By moving the piston 17b after a predetermined amount of the molten resin 11a is stored in the cylinder 17a, the molten resin 11a is extruded through the connecting pipe 27 from a slit provided in the T-die 18 and suspended to form a foamed resin sheet. 2 is formed.

The foamed resin sheet 2 is guided between the first and second molds 30 and 40 and molded by the molds 30 and 40 . The mold 30 has a convex portion 30 a on the surface facing the mold 40 . The mold 40 has a concave portion 40 a on the surface facing the mold 30 . The convex portion 30a and the concave portion 40a are substantially complementary to each other. The mold 30 is preferably provided with a large number of vacuum suction holes so that the foamed resin sheet 2 can be formed into a shape along the surface of the mold 30 by vacuum suction. The mold 40 may also be provided with vacuum suction holes. By containing the foaming agent in the molten resin, the foamed resin sheet 2 becomes a foamed resin sheet, and the molded body becomes a foamed molded body.

In addition, the skin sheet 3 is placed adjacent to the foamed resin sheet 2 so as to overlap with the foamed resin sheet 2, and the skin sheet 3 and the foamed resin sheet 2 are sandwiched between the molds 30 and 40. The resin sheet 2 (foamed resin sheet 2) can be integrally molded. As a result, as shown in FIG. 1, a molded product 1 is obtained in which the skin sheet 3 is integrally formed with the foamed resin sheet 2 .

3A and 3B illustrate the molding method of the molded body 1. In molding the molded body 1, in order to integrally mold the foamed resin sheet 2 and the skin sheet 3, first, as shown in FIG. , the foamed resin sheet 2 and the skin sheet 3 are supplied between the molds 30 and 40 . The thickness of the supplied foamed resin sheet 2 is slightly smaller than the distance between the molds 30 and 40 .

Next, as shown in FIG. 3B, the molds 30 and 40 are clamped. At this stage, the thickness of the foamed resin sheet 2 is smaller than the distance between the molds 30,40. Next, as shown in FIG. 3(C), the foamed resin sheet 2 is formed into a cavity shape, and the foamed resin sheet 2 and the skin sheet 3 are joined and integrated by welding. At this time, as described above, vacuum suction is performed through the vacuum suction holes provided in the molds 30 and 40 to increase the thickness of the foamed resin sheet 2 and shape it into the cavity shape of the molds 30 and 40 .

When the foamed resin sheet 2 is vacuum-sucked by both the molds 30 and 40, foaming of the foamed resin sheet 2 is promoted and the foamed resin sheet 2 expands. Since the foamed resin sheet 2 has the lowest viscosity (highest fluidity) near the center in the thickness direction, foaming is particularly promoted near the center in the thickness direction, and the foamed resin sheet 2 expands. As a result, a foamed resin sheet 2 having a large average cell diameter in the layer near the center in the thickness direction (central layer) and a small average cell diameter in the surface layer near the surface is obtained. Such a foamed resin sheet 2 has a sandwich structure in which a central layer having a large average cell diameter is sandwiched between surface layers having a small average cell diameter, so that it is lightweight and highly rigid.

The method for molding the molded body 1 has been described above. In this embodiment, burrs formed around the molded body 1 are cut off within the mold. By removing the burrs within the mold, there is no need to provide a separate step for deburring, and efficient deburring is possible. In addition, since there is no need to separately prepare a press machine or the like, large-scale equipment is not required, which is advantageous in terms of equipment investment.

Deburring for cutting burrs formed around the molded body 1 will be described below.

The molds 30 and 40 used for the molding have pinch portions 31 and 41 that abut against each other on the outer peripheral portion of the cavity corresponding to the molded body 1 . The foamed resin sheet 2 and the skin sheet 3 are crushed by these pinch portions 31 and 41 , and this portion becomes a parting line (PL) of the molded body 1 . Here, the foamed resin sheet 2 and the skin sheet 3 remaining outside the pinch portions 31 and 41 form burrs B. , 40.

First, outside the pinch portions 31 and 41 of the molds 30 and 40, the mold surface of the mold 30 is retracted to form a space 50 for accommodating the burrs B. As shown in FIG. As shown in FIG. 4A, a space 50 is formed outside the pinch portions 31 and 41, and the burr B is accommodated in this space 50. As shown in FIG.

The space 50 is closed at the opposite end by the pinch portions 32, 42 formed at a predetermined distance from the pinch portions 31, 41. As shown in FIG. That is, the space 50 is formed as a space between the pinch portions 31 and 41 as a first pinch portion and the pinch portions 32 and 42 as a second pinch portion. By making the space 50 a closed space in this way, the structure is such that air (cold air) blown from an air blowing mechanism, which will be described later, does not escape from the space 50 . In order to release air from these spaces 50 during air blowing, an air release pin may be inserted into the spaces 50, or another air release mechanism may be provided.

An air blowing mechanism and a protruding member are provided in the space 50, and are used to separate the burr B from the molded body 1. As shown in FIG. Specifically, in the case of the present embodiment, a blowout hole 43 for blowing air is formed corresponding to the space 50 in the mold 40 on the lower side in the drawing. Air (cold air) is blown out from the air blowing hole 43, and the burr B is blown with the cold air.

In this example, a first pinch portion (pinch portions 31, 41) is provided around the molded body, and a second pinch portion (pinch portions 32, 42) is provided outside the first pinch portion. , deburring is performed in the space formed between the first pinch portion and the second pinch portion. It is also possible to perform

On the other hand, in the figure, the upper mold 30 is provided with a mold slide mechanism 60 which is a protruding member in a position near the pinch portion 31 and arranged along the pinch portion 31 . The mold slide mechanism 60 is, for example, a rod-shaped member having a diameter of about 20 mm to 30 mm. impose.

The shape of the mold slide mechanism 60 is arbitrary, and for example, a rod-shaped body having a circular cross section may be used, or a rod-shaped body having a concave portion 60a in the center of the tip surface and an annular protrusion may be used. . Alternatively, a rod or the like having a protrusion 60b with a slightly smaller diameter at the tip can be used.

As described above, the mold slide mechanism 60 is arranged along the pinch portions 31 and 41, and the narrower the distance between them, the better the cutting performance. Therefore, it is preferable that the arrangement pitch (arrangement interval) of the mold slide mechanisms 60 is, for example, within 170 mm.

Further, as a means for operating the mold slide mechanism 60, for example, a hydraulic system can be adopted, and each mold slide mechanism 60 can be operated independently, or simultaneously using a mold back plate or the like. It is good also as a system which operates. Depending on the shape of the molded product, it is conceivable that deburring can be performed smoothly by making the contact timing of the mold slide mechanism 60 variable. In that case, the stroke of each mold slide mechanism 60 should be adjusted. can be adjusted as appropriate.

When deburring inside the mold, it is important to cool the burr B firmly and to optimize the settings of the mold slide mechanism 60 . In the case of the molded body 1 having the skin material (skin sheet 3), if punching is performed from the foamed resin sheet 2 side, the skin sheet 3 will not be cut, making it difficult to deburr without the mold. There are two factors for this: (1) the cooling blow hits the skin sheet 3 side at the burr B and the cooling efficiency drops, and (2) the force is not well transmitted to the skin sheet 3 at the parting line (PL). is mentioned.

Therefore, in this embodiment, as shown in FIGS. 4A and 4B, the mold slide mechanism 60 is projected from the skin sheet 3 side to punch out the burr B. As shown in FIG. That is, as shown in FIG. 4A, the mold slide mechanism 60 is incorporated in the mold 30 on the side that contacts the easy-to-skin sheet 3, and after the cooling blow, as shown in FIG. The die slide mechanism 60 is projected to cut off the burr B. As a result, the burr B is quickly cut.

When the mold slide mechanism 60 is protruded from the skin sheet 3 side and the burr B is punched out, the cooling blow is blown from the non-permeable foamed resin sheet 2 side, and the burr B (foamed resin sheet 2 and The skin sheet 3) adheres to the mold 40 and is sufficiently cooled. Further, the mold slide mechanism 60 directly hits the skin sheet 3, and the force of the mold slide mechanism 60 is surely transmitted to the skin sheet 3, so that smooth deburring is realized.

On the other hand, as shown in FIG. 5A, when a mold slide mechanism 60 is provided in the mold 40 on the foamed resin sheet 2 side, and the mold slide mechanism 60 projects from the foamed resin sheet 2 side, As shown in FIG. 5B, the skin sheet 3 cannot be cut, and deburring within the mold cannot be achieved.

When the mold slide mechanism 60 is protruded from the foamed resin sheet 2 side, the cooling blow is blown from the breathable skin sheet 3 side, and the non-breathable foamed resin sheet 2 adheres to the mold 30. do. On the other hand, the skin sheet 3 is insufficiently pressed against the foamed resin sheet 2 due to the cooling blow. The die slide mechanism 60 abuts against the foamed resin sheet 2 , but as described above, the skin sheet 3 does not adhere sufficiently to the foamed resin sheet 2 , and the force of the die slide mechanism 60 is transmitted to the skin sheet 3 . It is difficult to cut the skin sheet 3 reliably.

Further, in the present embodiment, the molded body 1 is punched, and this punching is also done in the mold in the same manner as the deburring described above. Conventionally, the molding 1 is punched after the product (molding 1) is removed from the mold. down can be achieved.

FIG. 6 is a diagram for explaining the drilling process in the mold. As described above, the foamed resin sheet 2 and the skin sheet 3 are sandwiched between the molds 30 and 40 for molding. If a receiving opening is formed at a position facing the mold slide mechanism, punching can be performed by the mold slide mechanism.

However, in punching the molded body 1, contrary to the case of cutting the burr B described above, the mold slide mechanism 70 for punching is provided in the mold 40 in contact with the foamed resin sheet 2, and the metal mold on the opposite side is provided. A receiving opening 80 is formed in the mold 30, and the mold slide mechanism 70 is protruded from the foamed resin sheet 2 side to perform perforation processing. By providing the mold slide mechanism 70 on the mold 40 on the side with which the foamed resin sheet 2 contacts, the foamed resin sheet 2 is cooled by coming into contact with the mold slide mechanism 70 to form a flat skin layer. This makes it possible to obtain a product (molded article 1) with high hole cut surface accuracy.

At the retracted position, the die slide mechanism 70 for punching forms a part of the molding surface of the one die 40 , and the tip surface of the die slide mechanism 70 comes into contact with the foamed resin sheet 2 . and cooled to form a flat skin layer.

First, as shown in FIG. 6A, a foamed resin sheet is formed by injecting molten foamed resin from a T-die while the skin sheet 3 is held in a mold 30 to form a foamed resin sheet. 2 is overlaid on the skin sheet 3, and the opposing molds 40 are clamped as shown in FIG. 6(B).

Next, as shown in FIG. 6(C), vacuum suction is performed from the vacuum suction holes provided in the molds 30 and 40 to increase the thickness of the foamed resin sheet 2 and to shape the cavities of the molds 30 and 40. shape. After that, as shown in FIG. 6(D), the mold slide mechanism 70 provided in the mold 40 is pushed out to cut off the burrs in the hole of the molded product 1 and remove them from the molded product 1 . Finally, as shown in FIG. 6(E), the mold is opened, and the perforated compact 1 is taken out.

7A and 7B are photographs showing the hole punching state, in which (A) and (B) are the case where the hole is punched by protruding the protruding member from the skin material side, and (C) and (D) are the protruding member from the resin sheet side. This is the case in which the hole is drilled by sticking out the 8A and 8B are diagrams schematically showing the state of hole opening, in which (A) is a case in which a hole is punched by protruding a protruding member from the skin material side, and (B) is a case in which the protruding member is protruded from the resin sheet side to form a hole. is performed.

When the projecting member (mold slide mechanism 70) is projected from the skin material side to form a hole, the foamed resin sheet 2 does not come into contact with the mold at the hole opening position, and the skin sheet 3 functions as a heat insulating material. Therefore, cooling becomes insufficient. In this state, when a projecting member (mold slide mechanism 70) is projected from the side of the skin sheet 3 to make a hole, the foamed resin sheet 2 is crushed, and the skin sheet 3 is torn off. The ends of 3 are also frayed and cannot be punched cleanly.

On the other hand, when the projecting member (mold slide mechanism 70) is projected from the foamed resin sheet 2 side to form a hole, the foamed resin sheet 2 is sufficiently cooled in contact with the mold, and the foamed resin sheet 2 is sufficiently hardened. Since the punching is performed from the side of the resin sheet 2, the skin sheet 3 integrated therewith is also neatly punched.

Although the embodiments to which the present invention is applied have been described above, it goes without saying that the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention. is.

For example, regarding the method of manufacturing a molded body, in the previous embodiment, the case of molding a resin sheet made of foamed resin was explained as an example. The present invention can be applied to any manufacturing method as long as burrs are formed around it. The resin sheet is not limited to a foamed resin sheet, and may be a non-foamed resin sheet.

1 molded body 2 foamed resin sheet 3 skin sheets 30, 40 molds 31, 32, 41, 42 pinch part 50 space 60, 70 mold slide mechanism 80 opening B burr

Claims (1)

A method for producing a molded body in which a molded body having a skin material is molded in a mold and a hole is made in the molded body,
Using a pair of divided molds, providing a projecting member in one mold and forming an opening for receiving the projecting member in the other mold,
The tip surface of the projecting member forms a part of the molding surface of the one mold at the retracted position,
A method for producing a molded article, characterized in that, when molding the molded article, a projecting member is protruded from the side opposite to the surface material in the mold to form a hole.

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