JPH01264826A - Molding method for synthetic resin molded product - Google Patents

Abstract

PURPOSE:To obtain a molded product where an uneven form is transferred and shaped on both sides, by a method wherein press molding of synthetic resin sheet in a plasticized state is performed by making use of two permeable and porous molds whose molding surface is provided with the uneven form and either the backsides of one side or both side molds are depressurized or the backside of one side mold is depressurized and that of the other side mold is pressurized. CONSTITUTION:A molding mold is constituted of a top and bottom molds 2, 3. The top mold 2 is constituted of a permeable and porous mold 6 obtained by molding a molding recessed part 4 and parting surface 5 integrally through electroforming and a supporting member 8. The bottom mold 3 is provided with a porous mold 15 where a molding protrusion 13 a little smaller than the molding recessed part 4 and a parting surface 14 are formed similarly and the supporting member 8. When a synthetic resin sheet 1 plasticized through heating is set up between both the molds and press-molded, for example, an embossed pattern 11 of a molding surface 4a is transferred to the surface and, for example, a groove 16 of a molding surface 13a is transferred to the backside, through which a molded product 21 where rib 22 is formed is obtained. Then, when the backside of the top mold 6 is depressurized and that of the bottom mold 15 is pressurized, transfer factors of the molding recessed part 4 and embossed pattern 11 are improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method of molding a synthetic resin molded product, and more particularly, to a method of molding a synthetic resin molded product by press molding and vacuum forming a synthetic resin sheet. It is something.

In addition, in this specification, the term "synthetic resin sheet"
Although the thickness is not limited, the thickness is usually 1 to 5 mm.

[Prior Art] There is a method of molding a synthetic resin molded product with a high transfer rate of a grain pattern by adding compressed air when vacuum forming a synthetic resin sheet (hereinafter referred to as vacuum-pressure forming). As shown in FIGS. 5 to 7, this includes a porous mold 53 on the vacuum suction side that has a molding recess 51 and a textured pattern 52, and a porous mold 53 on the compressed air side that has a plug part 54 that is considerably smaller than the four molded parts 51. This is carried out in the next step using a mold 55.

(2) As shown in FIG. 5, the synthetic resin sheet 56 plasticized by heating is set between both porous molds 53 and 55.

■ As shown in FIG. 6, both porous molds 53 and 55 are aligned, and the synthetic resin sheet 5
6 is entered into the molding recess 51 and preliminarily deformed.

- As shown in FIG. 7, the synthetic resin sheet 56 is vacuum-suctioned into the porous mold 53 by reducing the pressure on the back side of the porous mold 53, and the synthetic resin sheet 56 is vacuum-sucked into the porous mold 53 by applying pressure to the back side of the porous mold 55. By applying air pressure to the porous mold 53 side, the synthetic resin sheet 56 is vacuum-pressure formed,
At the same time, the grain pattern 52 is transferred onto the surface of the synthetic resin sheet 56. At this time, a gap is created between the back surface of the synthetic resin sheet 56 and the plug portion 54.

(2) At the same time as releasing the reduced pressure and pressurization, both porous molds 53 and 55 are opened, and the synthetic resin molded product 57 is released.

(2) Cutting off unnecessary portions of the synthetic resin sheet 56 from the synthetic resin molded product 57;

According to the above method, simple vacuum forming (the suction force is 1 kg)
/all), the transfer rate of the molded recesses 51 and the grain pattern 52 is improved by the amount of compressed air added to the vacuum suction (1 kg/a (+compressed air pressure)).

[Problems to be Solved by the Invention] However, in the vacuum-pressure forming described above, a gap is created between the back surface of the synthetic resin sheet 56 and the plug portion 54 during vacuum-pressure forming, and the synthetic resin sheet 56 is formed into the shape of the plug portion 54. Since it was not possible to restrain the synthetic resin sheet 5
There was a problem in that it was not possible to form an uneven shape or an uneven pattern such as ribs or grooves on the back surface of the sheet.

The present invention provides a method for molding a synthetic resin molded product, which can simultaneously mold a synthetic resin molded product and transfer an uneven shape or a pattern on both sides of the synthetic resin molded product, and which can also improve the transfer rate. is intended to provide.

[Means for Solving the Problem] In order to achieve the above object, in the method for molding a synthetic resin molded product of the present invention, two pieces of breathable porous gold having an uneven shape or an uneven pattern on the molding surface are used. Using a mold, a synthetic resin sheet in a plastic state is press-molded by the molding surfaces of both porous molds, and the synthetic resin sheet is vacuum-formed by reducing the pressure on the back side of one or both of the porous molds. ing.

Further, in addition to the press forming, the synthetic resin sheet may be vacuum-pressure formed by reducing the pressure on the back side of one porous mold and pressurizing the back side of the other porous mold.

[Function] When a synthetic resin sheet in a plastic state is press-molded by the molding surfaces of both porous molds, the synthetic resin sheet is constrained by both molding surfaces and flows, filling the space between them, so that the synthetic resin molded product is At the same time as being molded, the uneven shape or pattern is transferred onto both sides of the synthetic resin molded product.

Further, if the synthetic resin sheet is vacuum-formed by reducing the pressure on the back side of one or both of the porous molds, the transfer rate of the uneven shape or pattern provided on one or both of the porous molds will be increased.

In addition, if the synthetic resin sheet is vacuum-pressure formed by reducing the pressure on the back side of one porous mold and applying pressure on the back side of the other porous mold, the uneven shape or uneven pattern provided on the former porous mold can be formed. In addition to further increasing the transfer rate, the cooling effect and mold release properties of the synthetic resin sheet also increase.

[Example] To explain the example according to FIGS. 1 to 4, first,
The synthetic resin sheet 1 used in this example is made of vinyl chloride,
Vinylidene chloride, polyethylene, polypropylene, saturated polyester, polyamide (nylon, etc.), vinyl acetate copolymer, ABS.

It is made of various other thermoplastic synthetic resins or composite materials thereof.

Further, the molding die used in this example consists of an upper mold 2 having a molding recess and a lower mold 3 having a molding convex part.

The upper mold 2 includes an air-permeable upper porous mold 6 formed by integrally forming a molding recess 4 and a parting surface 5 by electroforming, and a back surface of the upper porous mold 6 in a sealed manner. A support frame 7 to support, a support member 8 to support the back surface of the upper porous mold 6, an epoxy resin filler 9 filled in the back surface of the support member 8, and screws to the upper bottom of the support frame 7. The bottom plate 10 is made up of

The upper porous mold 6 is formed to have a thickness of 3 to 7 mm by electroforming, and a textured pattern 11, which is one form of an uneven pattern, is formed on the molding surface 4a of the four molded parts 4 at the same time as the electroforming. Further, as shown in FIG. 3, the large number of ventilation holes 12 that make the upper porous mold 6 permeable are formed simultaneously with the electroforming by adjusting the electroforming as follows. The diameter increases toward the back side of the upper porous mold 6.

Here, the manufacturing method of the upper porous mold 6 will be briefly explained. (a) First, a mandrel (not shown) is provided with a convex part and a textured pattern that is the same shape as the four molding parts 4 and has a negative/positive relationship. Manufacture.

(b) Next, a mixture of pasty silver lacquer, butyl acetate and vinyl chloride lacquer is sprayed onto the surface of the mandrel to form a conductive coating. Since this conductive film is dotted with grains of polyvinyl chloride lacquer, a large number of minute non-conductive parts are formed.

(C) Next, the mandrel is immersed in a special plating solution containing nickel sulfamate and boric acid as main components and containing no pinhole suppressing surfactant.

When electricity is applied between the conductive coating (cathode) of the mandrel and the nickel electrode (anode), nickel is electrodeposited on the conductive coating, and the upper porous mold 6 is formed by electroforming. At this time, since nickel is not electrodeposited on the minute non-conductive portions of the conductive film, the non-electrodeposited portions grow to form the vent holes 12 with the enlarged diameter.

Continuing to explain the upper mold 2, the support member 8 is made by joining a large number of small metal balls 8a made of copper, iron, etc. with metal such as solder or synthetic resin such as epoxy resin. Since a gap is formed between 8a, it has air permeability.

Subsequently, the lower mold 3 includes a breathable lower porous mold 15 formed by integrally forming a molding convex portion 13 and a parting surface 14, which are slightly smaller than the molding recess 4, by electroforming, and the upper mold. It is composed of a support frame 7, a support member 8, a filler 9, and a bottom plate 10 similar to the mold 2.

This lower porous mold 15 is formed by electroforming in the same manner as the upper porous mold 6, and has a large number of ventilation holes 12. Furthermore, two grooves 6 are formed on the molding surface 13a of the molding convex portion 13 in place of the grain pattern.

A pressure reducing device 17 using a vacuum pump or the like is connected to the upper mold 2 through a ventilation pipe 18, and a compressed air device 19 using an air pump or the like is connected to the lower mold 3 through a ventilation pipe 20. ing.

Now, a method for molding a synthetic resin molded product using the above molding apparatus will be explained.

(1) First, as shown in FIG. 2, the upper mold 2 and the lower mold 3 are opened, and the synthetic resin sheet 1 plasticized by heating is set between them.

■ Next, as shown in FIG.
, 13a, the plasticized synthetic resin sheet 1 is
When press-molded at a press pressure of kg/CXl to 70kg/cx&, the synthetic resin sheet 1 forms both molding surfaces 4a, 13a.
It flows while being restrained by and fills between them.

Therefore, at the same time that the synthetic resin molded product 21 is molded, the molding concave portions 4 and the grain pattern 11 of the molding surface 4a are transferred and formed on the surface of the synthetic resin molded product 21, and the molding convex portions of the molding surface 13a are similarly formed on the back surface. The portion 13 and the groove 16 are transferred and shaped to form the rib 22.

As mentioned above, the press molding was performed at a press pressure of 20 kg/-
It is preferable to carry out the above process because the above-mentioned transfer shaping property (particularly the shaping property of the ribs 22) is improved.

(2) Further, the pressure reducing device 17 is activated to reduce the pressure on the back side of the upper porous mold 6, and the compressed air device 19 is activated to pressurize the back side of the lower porous mold 15, thereby removing the synthetic resin sheet 1 from the vacuum pressure. When molded, the synthetic resin sheet 1 is pressed against the molding surface 4a of the upper porous mold 6, so that the transfer rate of the molding recesses 4 and the grain pattern 11 is increased.

In addition, in the process of ■■ above, both porous molds 6 and 1
5 serves to cool the synthetic resin sheet 1 and return it from a plastic state to a hardened state.

In addition, by applying the compressed air, the transferability of the molding recesses 4 and the grain pattern 11 and the cooling effect of the synthetic resin sheet 1 are enhanced, and the subsequent release from the mold is also facilitated.

(2) Next, the vacuum and pressure are released, and both molds 2.3 are opened to release the synthetic resin molded product 21.

■ Cut out unnecessary parts of the synthetic resin sheet 1 from the synthetic resin molded product 21 (Fig. 4).

As described above, according to this embodiment, it is possible to mold the synthetic resin molded product 21 and at the same time transfer and form the uneven shape or pattern on both sides of the synthetic resin molded product 21, and the transfer rate can also be increased. can.

It should be noted that the present invention is not limited to the configuration of the above-mentioned embodiments, and may be modified and embodied as desired without departing from the spirit of the invention, for example, as described below.

(1) In the embodiment described above, air pressure from the lower porous mold 15 may not be applied. In this case as well, by vacuum forming using the upper porous mold 6, the transfer rate of the molded recesses 4 and the grain pattern 11 is improved. Although this molding method has a wide range of applications, it is particularly applicable to molded products where surface pattern is important (for example, automobile door sides, pillar interior parts, etc.).

Further, vacuum forming can also be performed by reducing the pressure on the back sides of both porous molds 6 and 15. By doing so, both the transfer rate of the grain pattern 11 of the upper porous mold 6 and the transfer rate of the grain pattern 16 of the lower porous mold 15 are almost equally improved.

This molding method is applicable to a wide range of applications, including molded products with a grained pattern on the surface and a mirror surface on the back (for example, containers,
It can also be applied to automobile console lids, glow box lids, etc.).

In the above embodiment, if a valve circuit is provided between the pressure reducing device 17 and the compressed air device 19 and the vent pipe 18, 20, or if a device capable of switching between reduced pressure and compressed air is used, the above molding method can be performed. Changes become easier.

(2) Instead of the porous mold 6.15, a porous mold in which ventilation holes are formed using a drill, a laser, etc. can also be used. In particular, the lower porous mold 15 has ribs 2
It is sufficient that the groove 16 has grooves 16 capable of forming the groove 2, and does not require precision such as a grain pattern, so there is no need to use the precise electroforming porous mold described above.

However, the electroformed porous molds 6 and 15 have many advantages, such as shortening manufacturing delivery time, reducing manufacturing costs, reducing labor, allowing for small hole diameters, unifying hole diameters, and reducing flow resistance due to diameter expansion. Therefore, it is extremely advantageous in various respects.

(3) The irregularities provided on the molding surface of the porous mold are not limited to the molding recesses 4, molding protrusions 13, or grooves 16, but include irregularities for forming component attachment parts on the synthetic resin molded product 21,
Various shapes such as unevenness for increasing or decreasing the thickness of a part of the synthetic resin molded product 21 can be provided.

(4) The uneven pattern provided on the molding surface of the porous mold is not limited to the grain pattern 11, and various patterns such as a stitch pattern, a stitch pattern, a wood grain pattern, etc. can be provided.

[Effects of the Invention] Since the present invention is configured as described above, it produces the following effects.

According to the molding method of claim 1, at the same time as molding a synthetic resin molded product, it is possible not only to transfer and form an uneven shape or a pattern on both sides of the synthetic resin molded product, but also to form an uneven shape on one or both sides. It is also possible to increase the transfer rate of uneven patterns.

According to the molding method of claim 2, it is possible to further increase the transfer rate of the uneven shape or uneven pattern on one side, and it is also possible to improve the cooling effect and mold releasability of the synthetic resin molded product.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a mold used in an embodiment of the present invention in a closed state, Fig. 2 is a sectional view of the mold in an open state, Fig. 3 is a partially enlarged perspective view of a porous mold, and Fig. 4 is a cross-sectional view showing the molded synthetic resin molded product, Figure 5 is a cross-sectional view of the mold used in the conventional method in the open state, Figure 6 is a cross-sectional view of the mold in the closed state, and Figure 7 is the same in the vacuum state. It is a sectional view at the time of pressure forming. 1...Synthetic resin sheet, 4...Molding recess, 4a...
- Molding surface, 6... Upper porous mold, 11... Grain pattern, 13... Molding convex portion, 13a... Molding surface, 15
...Lower porous mold, 16...grooves. Patent applicant: Gangnam Special Industry Co., Ltd.

Claims (1)

[Claims] 1. The molding surface (4a, 13a) has an uneven shape (4, 13, 1
6) or two porous molds (6, 15) with breathable porous material provided with an uneven pattern (11), both porous molds (
6, 15) by press-molding the synthetic resin sheet (1) in a plastic state using the molding surfaces (4a, 13a), and reducing the pressure on the back side of one or both of the porous molds (6). 1) A method for molding a synthetic resin molded product, characterized by vacuum forming. 2. Irregular shapes (4, 13, 1) on the molding surfaces (4a, 13a)
6) or two porous molds (6, 15) with breathable porous material provided with an uneven pattern (11), both porous molds (
The synthetic resin sheet (1) in a plastic state is press-molded using the molding surfaces (4a, 13a) of 6, 15), and the pressure is reduced on the back side of one porous mold (6), and the other porous mold (15) is pressed. A method for molding a synthetic resin molded product, characterized in that the synthetic resin sheet (1) is vacuum-pressure formed by applying pressure to the back side of the synthetic resin sheet (1).