WO2007080808A1

WO2007080808A1 - Method for manufacturing vacuum-molded piece

Info

Publication number: WO2007080808A1
Application number: PCT/JP2006/326288
Authority: WO
Inventors: Takashi Nishikawa
Original assignee: Calsonic Kansei Corporation
Priority date: 2006-01-10
Filing date: 2006-12-28
Publication date: 2007-07-19
Also published as: JP2007182035A

Abstract

A thermoplastic resin sheet (12) is heated at least from the front side so that the thermoplastic resin sheet (12) is at a temperature of a softening point of the thermoplastic resin sheet (12) or higher. The heated thermoplastic resin sheet (12) is vacuum-sucked and is adhered on a metal die (1) having a cavity plane (3) whereupon a fine uneven pressed shape (10) is formed. The fine uneven pressed shape (10) is transferred to the front side of the thermoplastic resin sheet (12) by cooling the metal die (1) while vacuum-sucking the thermoplastic resin sheet (12) adhered on the metal die (1).

Description

Specification

Manufacturing method of vacuum molded products

Technical field

[0001] The present invention relates to a method for manufacturing a vacuum molded product having a fine uneven-stretched shape on its surface.

Background art

[0002] Molded resin products used for automobile interior materials and the like may be given a fine uneven drawing shape such as high-grade suede tone, natural leather tone, and dense pore tone on the surface in order to enhance the texture. For example, as disclosed in JP-A-2004-322392, as a method for imparting this fine uneven drawing shape, a resin molded product is injection molded by applying sufficient temperature and pressure to a thermoplastic resin. Thus, a method of imparting a fine uneven drawing shape to the surface of the molded resin product is known.

[0003] However, injection molding requires large-scale equipment and is costly. For this reason, it has been examined whether or not a minute uneven drawn shape can be formed by vacuum forming that requires relatively simple equipment. However, in vacuum forming, even if the surface of the resin sheet was temporarily formed into a shape corresponding to the fine uneven drawing shape of the mold in the initial stage of vacuum suction, it was formed by the restoring force of the resin. There is a risk that the fine uneven diaphragm shape will collapse in the mold.

[0004] The present invention has been made paying attention to such a conventional technique, and provides a manufacturing method of a vacuum molded product capable of transferring a fine uneven drawing shape even by vacuum forming.

Disclosure of the invention

[0005] The invention of claim 1 that achieves the above object is that the thermoplastic resin sheet is at least on the surface side so that the thermoplastic resin sheet has a temperature equal to or higher than the softening point of the thermoplastic resin sheet. The heated thermoplastic resin sheet is vacuum-sucked to adhere to a mold having a cavity surface on which a fine concavo-convex drawing shape is formed, and the thermoplastic resin sheet in close contact with the mold is obtained. The mold is cooled while being vacuum-sucked to transfer the fine uneven drawing shape onto the surface of the thermoplastic resin sheet.

Brief Description of Drawings

FIG. 1 is a cross-sectional view showing a mold and a plug assist according to an embodiment of the present invention. The

FIG. 2 is an enlarged cross-sectional view showing a DA portion indicated by an arrow in FIG.

FIG. 3 is a cross-sectional view showing a heating state of a thermoplastic resin sheet.

FIG. 4 is a cross-sectional view showing a state immediately before the mold thermoplastic resin sheet is vacuum-sucked.

FIG. 5 is a cross-sectional view showing a vacuum-formed product.

FIG. 6 is an enlarged cross-sectional view showing a DB portion indicated by an arrow in FIG.

FIG. 7 is a diagram showing a molding cycle in a table.

FIG. 8 is a table showing molding conditions and molding results.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

1 to 8 are diagrams showing an embodiment of the present invention. The structure of the mold 1 used in this embodiment will be described with reference to FIGS. The mold 1 is also used in combination with the core type plug assist 2.

The mold 1 is an electric mold in which a surface cavity surface 3 is formed by an electric power layer 4. The cavity surface 3 is formed with a fine uneven diaphragm shape 10. The electrical layer 4 is excellent in terms of durability, which is easy to form the fine concave and convex shape 10 of the cavity surface 3. A vacuum suction hole (not shown) is formed on the entire cavity surface 3. The diameter of the vacuum suction hole is preferably 100 m or less, although it depends on the size of the fine uneven diaphragm shape 10. If it is 100 m or less, the transfer of the vacuum suction hole itself can be prevented.

A plurality of hot pipes 5 and cold pipes 6 are alternately provided on the back surface of the electric layer 4. A warm fluid can flow through the hot pipe 5 and a cold fluid can flow through the cold pipe 6. The hot pipe 5 and the cold pipe 6 are respectively connected to the back surface of the electric layer 4 by brazing 7. The pitch of the hot pipe 5 and the cold pipe 6 should be set as finely as possible to prevent temperature variations. The hot pipe 5 and the cold pipe 6 are surrounded by a heat insulating material 8, and the electric layer 4 and the heat insulating material 8 are held by a backing material 9.

Next, a method for producing a vacuum molded article 11 made of resin with the fine uneven drawn shape 10 transferred using the mold 1 will be described. [0012] First, as shown in the molding cycle of FIG. 7, in step 1, a thermoplastic resin sheet (TPO) 12 as an automobile interior material is held and set by a clamp 13, and the mold 1 is heated. Start. Heating of the electric layer 4 of the mold 1 is performed by flowing a warm fluid through the hot pipe 5.

[0013] Next, in step 2, the thermoplastic resin sheet 12 is heated from the upper and lower surfaces by the heater 14 so that the temperature of the thermoplastic resin sheet 12 is equal to or higher than its soft point. In this embodiment, the thermoplastic resin sheet 12 is heated so that the temperature becomes 190 ° C.

[0014] Although the thermoplastic resin sheet 12 may be heated only by the surface side force, it is possible to suppress variations in the direction of the temperature of the heat applied from both surfaces. Further, if the temperature of the thermoplastic resin sheet 12 is heated so as to be equal to or higher than the soft low point, the transferability can be improved. In the case of TPO, it is preferable to heat to 160 to 210 ° C. (preferably 170 to 200 ° C.).

Next, in step 3, when the mold 1 reaches a predetermined temperature, the plug assist 2 is lowered and the thermoplastic resin sheet 12 is pressed against the cavity surface 3 of the mold 1.

[0016] Next, in Step 4, apply vacuum pressure of 0.2MPa (preferably 0.05MPa to 0.5Mpa force) from plug assist 2 force, and vacuum suction from cavity surface 3 with a delay of about 0.1 second. To do. There is no need to use compressed air from Plug Assist 2, but the transfer will improve if there is one.

[0017] Next, in step 5, the compressed air is stopped, the supply of the warm fluid to the warm pipe 5 is stopped while maintaining the vacuum suction, and the cold fluid is circulated through the cold pipe 6 instead. Cool mold 1. In the present embodiment, the mold 1 is cooled until the electric layer 4 of the mold 1 reaches 70 ° C. It is desirable to perform this cooling in a short time. By cooling in a short time, it is possible to stabilize the shape of the fine irregularities drawn shape 10 transferred to the molded thermoplastic resin sheet 12, and to facilitate the release from the mold 1. Because it can.

[0018] Next, in Step 6, with the mold 1 kept cooled, the pressure in the vacuum suction hole is released to the atmospheric pressure, the plug assist 2 is raised, and the vacuum molded article 11 is removed from the mold. The cooling temperature of the mold 1 is preferably 60 ° C. to 80 ° C. If the cooling temperature of the mold 1 is extremely low, if the molding cycle time is extended and the productivity is lowered, a problem arises. This is the force that causes the V or U problem when deformed or the product lacks dimensional stability. According to the above embodiment, when the thermoplastic resin sheet 12 is vacuum-formed by the metal mold 1, the mold is performed while the thermoplastic resin sheet 12 is vacuum-absorbed I on the cavity surface 3. In order to cool 1, the fine irregularity drawn shape 10 of the thermoplastic resin sheet 12 transferred in accordance with the cavity surface 3 of the mold 1 in the initial stage of vacuum suction can be stabilized as it is. Therefore, it is possible to transfer a fine uneven drawing shape even in vacuum forming that does not require large-scale equipment.

[0020] Next, the relationship between the surface temperature of the mold 1 and the transferability of the thermoplastic resin sheet 12 will be described.

First, the surface temperature of the mold 1 was set to eight temperatures from 150 ° C. to 70 ° C., and the transferability of the thermoplastic resin sheet 12 at each temperature was evaluated.

[0022] Fig. 8 shows the results of evaluation of the shape transferability of these 8 types of samples (No. 1 to 8) and the transferability of the fine irregularities 10 (the "skin" in Fig. 8 is a thermoplastic resin sheet) 12).

[0023] Samples Nos. 2 to 5 were good in both shape transfer and squeeze transfer. That is, the surface of the vacuum molded product 11 was surely transferred up to the fine portion of the fine concavo-convex drawing shape 10. In this way, it was possible to reliably transfer the fine portions of the fine uneven diaphragm shape 10 to the mold surface 1 while the thermoplastic resin sheet 12 was vacuum-formed and cooled, and transferred according to the cavity surface 3. This is because the fine concave / convex diaphragm shape 10 can be stabilized as it is.

[0024] On the other hand, Sample No. 1 in which the temperature of the mold 1 was high had an inferior R shape at the bent portion in terms of shape transfer. Also, in terms of the drawing transfer property, an air accumulation occurred in the part that contacted the cavity surface 3 earlier, and the appearance was poor immediately.

[0025] In Samples Nos. 6 to 8 where the temperature of the mold 1 was low, even the fine portions of the fine concavo-convex aperture shape 10 were reliably transferred. In Sample 8, the R shape of the bent portion was slightly poor in terms of shape transfer.

[0026] From the above, in the case of the thermoplastic resin sheet (TPO) 12, it can be said that the heating temperature of the mold 1 is preferably 100 to 140 ° C.

[0027] In the above description, an example in which the mold 1 is provided with the warm pipe 5 and the cold pipe 6 and the mold 1 is heated and cooled by flowing a warm fluid and a cold fluid respectively, is shown. Without limiting to this, common pipes are provided at a predetermined pitch, and by switching the valves, etc., hot fluid is allowed to flow through all pipes or cold fluid is allowed to flow to select heating and cooling of the mold 1. May go Industrial applicability

The present invention is not limited to automobile interior parts, and can be applied to any vacuum-formed product having a fine uneven drawing shape.

Claims

The scope of the claims

The thermoplastic resin sheet is heated at least from the surface side so that the thermoplastic resin sheet has a temperature equal to or higher than the soft temperature of the thermoplastic resin sheet,

Vacuuming the heated thermoplastic resin sheet to bring it into close contact with a mold having a cavity surface on which fine irregularities are formed,

A vacuum forming characterized by transferring a fine uneven drawing shape onto the surface of the thermoplastic resin sheet by cooling the mold while vacuum sucking the thermoplastic resin sheet adhered to the mold. Product manufacturing method.