JPS63303710A - Manufacture of decorative molding for automobile - Google Patents

Abstract

PURPOSE:To contrive to improve the impact resistance at low temperature, while all resin material is melted sufficiently, whereby excellent molding is achieved by a method in which the insulating layer composed of a specified material is caused to intervene between the resin material in a cavity and a top force, and then said resin is molded in high frequency. CONSTITUTION:Molding material 5 is thrown into the recessed portion 2a of a bottom force 2. Next, on this molding material 5, an insulating sheet 7 with flexibility is placed. This insulating sheet is the material having a small loss in a high frequency treatment and excellent insulating characteristics, and is composed of, e.g. polyethylene, silicon and fluorine resin, etc. After a top force 1 and the bottom force 2 have been clamped in the state of said insulating sheet 7 being nipped therebetween, a prescribed high frequency voltage is applied between an upper electrode plate 3 and a lower electrode 4. Consequently, the molding material 5 is heated and melted, and the molding is molded. Since the insulating sheet 7 is caused to intervene between the heated molding material 5 and the top force 1, the generated heat does not escape to the side of the top force 1, whereby the total molding material 5 is melted at uniform and sufficiently high temperature, and then the excellent molding is achieved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for manufacturing decorative moldings for automobiles using high-frequency molding.

2. Description of the Related Art A method using high-frequency molding has been known as a method for manufacturing decorative moldings for automobiles.

Fig. 3 explains a method for manufacturing a molding using conventional high-frequency forming. and non-conductive materials such as silicone resin and polyethylene.

, a lower mold 2 made of polypropylene, ceramics, or the like, and a cavity corresponding to the desired mold shape is defined between them. The upper mold 1 and the lower mold 2 are respectively fixed to an upper electrode plate 3 and a lower electrode plate 4 of a high-frequency molding machine.

Further, as the molding material 5, a resin having a large high frequency loss, such as vinyl chloride, nylon, EVA, etc., or a pellet-like or powder-like material obtained by mixing a small amount of a foaming agent with the resin is used.

That is, to mold a molding using this method, first a predetermined amount of molding material 5 is placed in the upper mold 1. Insert into the cavity between the lower molds 2. Then, upper mold 1. After clamping the lower mold 2, the upper electrode plate 3. A high frequency voltage is applied between the lower electrode plates 4. As a result, the molding material 5 made of vinyl chloride or the like self-heats, melts and softens, and foams if it contains a foaming agent. Therefore, if it is taken out after cooling, a molding 6 that conforms to the shape of the cavity can be obtained as shown in FIG.

In some cases, the resin material is preformed into a sheet by extrusion molding, and this is then cut to a predetermined length to obtain the molding material 5 (Japanese Patent Laid-Open No. 58-38
40, JP-A-58-3826, etc.).

Problems to be Solved by the Invention However, in the conventional molding manufacturing method using high-frequency forming as described above, since the upper mold 1 is made of metal such as aluminum, the molding material 5 self-heats. The heat from this process easily escapes to the upper electrode plate 3 through the upper mold 1, which means that the part of the molding material 5 in the cavity that is close to the upper mold l (the part that is normally on the back surface 6a side of the molded molding 6) is cooled. It may get stuck and not be melted sufficiently.

Therefore, the bond between the resin materials becomes relatively weak, and for example, when the molding material 5 is made into a pellet shape, in the state after molding,
As shown in Fig. 4, pellet particles remain on the back surface 6a of the molding 6, resulting in very poor impact resistance, especially impact resistance at low temperatures. . Note that since the lower mold 2 is made of a silicone resin or the like having heat insulating properties, the above-mentioned heat transfer does not occur.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention has a resin in a cavity defined between an upper mold made of a conductive metal and a lower mold made of a non-conductive material. In the manufacturing method of a decorative molding for an automobile, which involves inserting a material and applying a high-frequency voltage to the molding material, the material is inserted into the molding material, and a high-frequency voltage is applied to the molding material. It is characterized by interposing a heat insulating layer made of a different material, and performing high-frequency molding in this state.

The resin material inserted into the working cavity generates heat by itself due to the high frequency voltage and melts (if it contains a foaming agent, it foams at the same time). Here, a heat insulating layer with high heat insulation properties is interposed between this self-heated resin material and the upper mold made of conductive metal, so the transfer of heat to the upper mold is prevented, and therefore the upper mold Even the parts close to the mold reach a sufficiently high temperature and melt, yielding a molding in which the resin material is firmly bonded.

Embodiment FIG. 1 shows an embodiment of the method for manufacturing a decorative molding for an automobile according to the present invention. Note that the upper mold 1, lower mold 2, and other high-frequency molding machines themselves are not particularly different from conventional ones, so their explanations will be omitted.

First, a predetermined amount of pellet-shaped molding material 5 is poured into the recess 2a of the lower mold 2 corresponding to the cavity.

As described above, this molding material 5 is made of a resin having a large high frequency loss, such as vinyl chloride, nylon, EVA, etc., or a mixture of these resins with a small amount of a foaming agent. As the molding material 5, a powder or paste material may be used as it is, or a sheet may be preformed and then cut into a predetermined size.

Next, a flexible heat insulating sheet 7 is placed on top of the molding material 5 and is large enough to cover it.

The heat insulating sheet 7 is made of a material with low high frequency loss and high heat insulating properties, such as polyethylene, silicone, fluororesin, etc.

Then, with this heat insulating sheet 7 sandwiched between them, the upper mold l and the lower mold 2 are
After the molds are clamped, a predetermined high frequency voltage is applied between the upper electrode plate 3 and the lower electrode plate 4.

As a result, the molding material made of vinyl chloride or the like generates heat and melts, and if it contains a foaming agent, it simultaneously foams, forming a molding that follows the shape of the cavity.

Here, between the self-heated molding material 5 and the upper mold l,
Since the heat insulating sheet 7 made of polyethylene or the like is interposed, the generated heat will not escape to the upper mold l side.
The entire molding material 5 within the cavity reaches a uniform and sufficiently high temperature and melts, allowing good molding to be performed. Therefore, in the molded mold, for example, no pellet-like material shape remains, and a product with excellent impact resistance can be obtained.

Note that the heat insulating sheet 7 itself does not generate heat, and does not join with the molded molding.
It can be easily peeled off after molding and can be reused.

Next, Figure 2 shows an upper mold made of conductive metal! On the mold surface of
An example is shown in which a thin heat insulating layer 8 is fixed in advance.

In this case, the heat insulating layer 8 is made of the above-mentioned polyethylene or silicone since flexibility is not required.

In addition to fluororesin, ceramics can also be used.

Effects of the Invention As is clear from the above explanation, in the method for manufacturing a decorative molding for an automobile according to the present invention, a heat insulating layer is interposed between the resin material and the upper mold during high-frequency molding, so that self-heating is generated. The transfer of heat from the resin material to the upper mold can be prevented, and the entire resin material can be sufficiently melted to perform good molding. Therefore, it is possible to provide a molding that has excellent impact resistance, especially at low temperatures, compared to moldings produced using conventional manufacturing methods.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the manufacturing method according to the present invention, FIG. 2 is a sectional view showing a different embodiment of the invention, FIG. 3 is a sectional view showing a conventional manufacturing method, and FIG. is a sectional view of a molding molded by this conventional manufacturing method. 1... Upper mold, 2... Lower mold, 3... Upper electrode plate, 4
... lower electrode plate, 5 ... molding material, 7 ... heat insulation sheet, 8 ... heat insulation layer. Figure 1 Figure 2 @ Figure 3 Figure 4

Claims (1)

[Claims] (1) A car that is high-frequency molded by inserting a resin material into a cavity defined between an upper mold made of a conductive metal and a lower mold made of a non-conductive material, and applying a high-frequency voltage to the cavity. A method for manufacturing a decorative molding for use in a mold, in which a heat insulating layer made of a material with low high frequency loss and high heat insulation properties is interposed between the resin material in the cavity and the upper mold, and high frequency molding is performed in this state. A method of manufacturing a decorative molding for an automobile.