JPS58217317A - Vacuum molding - Google Patents

Abstract

PURPOSE:To prevent the thickness of a sheet from reducing partially and to transfer a pattern excellent in transferability to a sheet by a method wherein after a synthetic resin sheet is prestretched by a male mold approximately into a formed shape, it is clamped by said male mold and a vacuum forming female mold to perform a vacuum molding. CONSTITUTION:To take an example, by the use of the male mold 4 that can regulate temperature by a cartridge heater 3, a synthetic resin sheet 1 is prestretched approximately into a formed shape, the vacuum forming female mold 5 and the prestretching male mold 4 that can regulate temperature by a cartridge heater 6 are closed, then simultaneously vacuum drawing is performed by the female mold 5, pressurizing is made by the male mold 4, he synthetic resin sheet 1 is vacuum-molded to transfer a pattern such as stitch, etc. on the surface of the convex side. EFFECT:Patterning is made at low cost.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for vacuum forming a synthetic resin sheet, and more specifically, a method for vacuum forming a sheet made of a semi-hard polyvinyl chloride using a soft molding machine, and at the same time forming patterns such as stitches and grains on the sheet. The present invention relates to a vacuum forming method for transferring. □ For example, conventional methods for adding patterns such as grains and stitches to automobile instrument springs/I- (hereinafter referred to as instrument panel skins) include a method using a roller, a mold coating method, and a slush molding method. These conventional methods have the disadvantage that problems such as curling occur when rollers are used, and that the mold coating method and slush molding method are expensive.

Furthermore, in vacuum forming methods that transfer patterns such as stitches and grains during vacuum forming, when vacuum forming is performed using a female mold that has the pattern to be transferred onto the mold surface, the sheet becomes partially thinned, resulting in poor transferability. That problem is a hot topic.

The present invention is intended to solve the above problems, and its purpose is to prevent thinning of the sheet by using a pre-stretching male mold together with a vacuum forming female mold, and to prevent the sheet from becoming thinner. It is an object of the present invention to provide a vacuum forming method that increases the degree of vacuum by improving the sealing performance with the female mold, thereby obtaining excellent transferability of stitches, grains, etc.

In the vacuum forming method according to the present invention, a synthetic resin sheet is pre-stretched using a male die into a shape similar to the shape after vacuum forming.
The present invention is characterized in that the discrete pieces for vacuum forming are clamped together with the male die and vacuum formed.

Embodiments of the present invention will be described below with reference to the drawings.

The first embodiment of the method of the present invention will be described with reference to FIGS. 1 to 4. First, as shown in FIG. do.

The instrument panel skin material l used for molding is made of soft or semi-hard thermoplastic or resin such as polyvinyl chloride, polyglopylene, polyethylene, or ABS resin.

Next, as shown in FIG. 2, a male mold 4 whose temperature has been adjusted by a plurality of cartridge heaters 3 is moved while being pushed from above the heated skin material 1, and this male mold 4 is used to heat the skin material it-
Pre-stretch in a convex shape.

This male mold 4 is a resin mold or a metal mold, and has a plurality of cartridge heaters 3 built in near the surface as necessary.

The surface of this male mold 4 is the same as the surface of the female mold 5, which will be described later.
The shape is reversed, that is, it is stepped and convex.

In addition, since the transferability of grains, stitches, etc. is poor if only the vacuum from the female mold 5 is applied, a ventilation hole was also provided in the male mold 4 to facilitate vacuum forming by applying air pressure at the same time as the vacuum.

Subsequently, the female mold 5 whose temperature has been adjusted by a plurality of IJ heaters 6 is moved from below the skin material 1, and the mold is closed with the male mold 4 as shown in FIG. The female mold 5 is a porous mold for vacuum forming, and a pattern for transfer is formed on the mold surface in order to put a pattern such as a stitch or a grain on the convex surface of the skin material 1. The adjusted temperature of the female mold 5 varies depending on the design of the skin material 1, but is preferably 40 to 90°C.

4, the vacuum level is -4 by the female mold 5 as shown in Fig. 4.
Vacuum is applied at 00 to -600 trrnHg and at the same time air is evacuated from the male die 4 at 21'#/d to form the skin material into a predetermined shape and stitch on the convex surface.

Patterns such as grains were transferred and then cooled to obtain an automobile instrument panel skin.

5 to 8 show the steps of a second embodiment of the present invention. This embodiment is an example in which the arrangement of the male die 3 and the female die 5 in the first embodiment is upside down, and the process is performed in the first embodiment.
It is similar to FIG. 4. That is, first, the skin material 1
(see FIG. 5), the heated skin material l is moved from below by a male die 4 whose temperature is adjusted by a cartridge heater 3, and is pre-stretched into a convex shape.
), then the female mold 5 whose temperature has been adjusted to A with the cartridge heater 6 is moved from above to clamp the mold (see Fig. 7), and then the female mold 5 is evacuated and the skin material l is heated to a predetermined level. It was molded into a shape, and patterns such as stitches and grains were transferred to the surface (see Fig. 8), and cooled to obtain an instrument panel skin having a desired pattern.

Next, specific molding conditions for the first and second embodiments are shown in the table below.

If the vacuum forming of the first or second embodiment is carried out under the conditions listed in the table, thinning of the skin material l during vacuum forming will be prevented and the thickness of the molded product will be uniform (0.9 m). , and skin material 1
The sealability between the mold and the female mold 5 was improved, and the transferability of stitches, grains, etc. was also improved, and an instrument panel skin with fine patterns was obtained.

In addition, according to the conventional vacuum forming method, a sheet having a thickness L3 is vacuum formed using only the female die 5 without preliminary stretching. =,o,
Thin parts of the i-layer occurred, and the transferability of stitches, grains, etc. was also poor.

As explained above in E7, according to the method of the present invention, before vacuum forming is performed using a female mold for vacuum forming, a synthetic resin sheet is pre-stretched using a male mold into a shape similar to the shape after vacuum forming.
This method prevents partial thinning of the sheet, and improves the sealing performance between the female mold and the sheet by closing the sheet, thereby increasing the degree of vacuum compared to conventional methods. Therefore, according to the present invention, when molding with a female mold and transferring patterns such as stitches and grains, it is possible to obtain excellent transferability of these patterns. Moreover, the method of the present invention has the advantage that it can be performed at lower cost than methods of forming patterns such as scratches, grains, etc. on a sheet by the morbi coat method or the slush molding method.

[Brief explanation of the drawing]

Figures 1 to 4 are process diagrams showing the first embodiment of the present invention, in which Figure 1 shows a state in which the skin phase is heated, and Figure 112 shows a state in which the skin material is pre-stretched with a male die. Figure 3 is a diagram showing a closed state of the mold, Figure 41 is a diagram showing a state in which 7c is being molded with a female mold, and Figures 5 to 8 are a diagram showing a second embodiment of the present invention. FIG. 6 is a diagram showing a state in which the skin material is heated, FIG. 6 is a diagram showing a state in which the skin material is pre-stretched in a male mold, and No. 719 is a diagram showing a state in which the mold is closed. The figure shown in Fig. 8 is a view showing a state in which true wall molding is performed using a female die. In the figure, l... epidermis 2... heater 3, j
i) Ridge heater 4...male type 5...female W
6...Cartridge heater (1 person)

Claims (1)

[Claims] (1) A vacuum method characterized in that a synthetic resin-covered sheet is pre-stretched using a male mold into a shape similar to the shape after vacuum forming, and then a female mold for vacuum forming is clamped with the male mold for vacuum forming. Molding method.