JPH0698693B2 - Manufacturing method of automobile decorative mold - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a method for manufacturing an automobile decorative molding using a high frequency heating method.

2. Description of the Related Art Conventionally, as a method for producing the decorative molding, Japanese Patent Laid-Open No.
Japanese Patent Publication No. 29 discloses a method of forming a non-foamed skin layer by heating the outer surface of a molding made of a foamed resin material in a silicon mold with high frequency.

Further, the applicant of the present application discloses, in JP-A-61-72676, that a lower mold made of a silicone resin is filled with granular pellets made of a foaming resin material, and then the lower mold is made of a metal having high thermal conductivity. In addition, a method is proposed in which the upper mold is assembled and the pellets are heated at high frequencies in the upper and lower molds to form a skin layer on the surface in contact with the lower mold.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in such a conventional method for manufacturing a decorative molding, since the raw material material is granular, it is possible to strictly control the molding shape in the mold. It is difficult, especially when the molding has a three-dimensionally changing shape, the density of the pellets tends to vary when the shape is held in the mold, and it is difficult to obtain a homogeneous product. There was a problem. In addition, even in the case of manufacturing a normal flat decorative molding, there is a drawback that the operation is complicated because a predetermined amount must be measured when setting the granular pellets in the lower mold. is doing.

Therefore, an object of the present invention is to solve the problems of the conventional method for manufacturing a decorative molding for automobiles and to provide a uniform and easy manufacturing method.

Means for Solving the Problems After preheating the granular pellets mainly composed of a foamable resin, the granular pellets are continuously passed between rolling rolls, and a long gap having an appropriate gap between the granular pellets is held. After creating a length sheet and cutting the long sheet into a predetermined size, the length sheet is filled in a lower die having heat resistance and made of a non-conductive material and an upper die made of metal having high heat conductivity, Provided is a method of subjecting the sheet to high-frequency heat treatment in the upper and lower molds to perform melt molding.

Action Granular pellets are preheated, and when they pass between rolling rolls, long seeds having a structure in which appropriate gaps are held mutually are created, so this long sheet is cut into a predetermined shape. Then, high-frequency heat treatment can be performed in the mold. The foaming air generated by the sheet during the high-frequency heat treatment passes upward through the voids, and at the same time, a uniform skin layer is formed on the molding surface in contact with the lower mold.

Examples Hereinafter, one example of a method for manufacturing an automobile decorative molding according to the present invention will be described with reference to the drawings. FIG. 1 is a schematic view showing a manufacturing process according to the present invention. In the figure, 1 is a hopper into which a granular pellet 2 as a raw material is charged, and the granular pellet 2 is fed from a lower end opening 1a of the hopper 1 to a belt conveyor 3 Drop continuously on top. The belt conveyor 3 has rotating shafts 4, 5
Is rotating endlessly by means of the granular pellet 2
Are conveyed in the direction of arrow A. Reference numeral 6 is a heating lamp, which is disposed above the belt conveyor 3 in close proximity to the granular pellets 2.
Preheat. Numerals 7 and 8 denote rolling rolls, which are preheated by a heating lamp 6 and are in the semi-molten state of the granular pellets 2 described above.
Is rolled into a long sheet. The obtained long sheet 9 has suitable voids between the granular pellets 2 and maintains a shape in which they are mutually connected, and is cooled and solidified. A cutting member 10 cuts the long sheet 9 that has been cooled and solidified to a predetermined size to form a sheet unit 11. still,
The granular pellet 2 has a round bar shape as shown in FIG.
A foaming agent such as azodicarbonamide is mixed with a synthetic resin such as vinyl chloride or ethylene vinyl acetate.

Reference numeral 12 is a high-frequency molding device for melt-molding the sheet unit 11, and includes a lower mold 13 and an upper mold to be assembled with the lower mold 13.
14, an electrode plate 15 provided on the lower surface of the lower mold 13, an electrode plate 16 provided on the upper surface of the upper mold 14, and a power supply 17 for applying a high-frequency current to both electrode plates 15 and 16 are mainly configured. There is. The lower mold 13 is made of a material having heat resistance and made of a non-conductive material, such as a silicon mold, and a recess 18 having a predetermined shape set in advance is formed on the lower mold 13. The seat unit 11 is filled in the recess 18.

On the other hand, the upper mold 14 is made of a metal having a high thermal conductivity, such as aluminum.

In the state shown in the figure, that is, when the recess 18 of the lower mold 13 is filled with the sheet unit 11 and the upper mold 14 is assembled and the electrode plates 15 and 16 are set, the power supply 17 is activated to apply high-frequency waves to both electrode plates 15 and 16. A current is applied for a predetermined time. Then, the sheet unit 11 filled between the lower mold 13 and the upper mold 14 foams at about 100 to 200 ° C,
The foamed air escapes upward through the gaps between the granular pellets 2 forming the sheet unit 11 and the upper mold 14 and the lower mold.
It diffuses to the outside through the minute clearance formed between 13 and it. Also, by the above heating, a lower mold made of a heat resistant material
A smooth skin layer 19 is formed on the surface of the sheet unit 11 in contact with 13. That is, the skin layer 19 is formed by cooling and solidifying the granular pellets 2 after they are completely melted, and a smooth and glossy surface can be obtained. Therefore, the skin layer 19 forms the surface layer of the completed decorative molding.

Sheet unit after application of high-frequency current as described above
11 is cooled and solidified as it is, and completed as a decorative molding having the skin layer 19 formed on the surface thereof. FIG. 3 shows the back surface side of the obtained decorative molding 20, that is, the surface on the side where the skin layer 19 is not formed.

The strength and appearance of the obtained decorative molding can be changed by changing the application time or the power of the high frequency current in the high frequency molding device 12.

As described above, according to the present invention, after the granular pellets mainly composed of the expandable resin are preheated, they are continuously passed between the rolling rolls to form an appropriate gap between the granular pellets. After making the held long sheet and cutting the long sheet into a predetermined size, it is placed in a lower mold made of a non-conductive material having heat resistance and an upper mold made of a metal having a large thermal conductivity. Since the sheet is filled and subjected to high-frequency heat treatment in the upper and lower molds to be melt-molded, it has the following operational effects. That is, since the granular pellets are interconnected and fixed in a coarse state by performing the above-described preheating and rolling roll treatment, the density of the granular pellets when subjected to high frequency heating in the next step. Does not vary, and even if the product has a three-dimensionally changing shape, there is no problem, and it is possible to obtain a homogeneous molding material. Further, since the long sheet obtained by the rolling roll can be cut into a desired size and shape and subjected to high-frequency heating in the next stage, a decorative molding having a desired shape can be easily obtained. In addition, since the operation of measuring the granular pellets at the time of molding can be omitted, there is an advantage that the operability is improved. Further, during high frequency molding, the foaming air escapes upward through the voids formed between the granular pellets, so that air voids and the like are prevented from being formed in the obtained product, and the appearance is improved.

[Brief description of drawings]

FIG. 1 is a schematic process diagram showing a method for manufacturing a decorative molding according to the present invention, FIG. 2 is a perspective view showing the shape of a granular pellet, and FIG. 3 is a back view showing an example of the obtained decorative molding. 1 ... Hopper, 2 ... Granular pellet, 3 ... Belt conveyor, 6 ... Heating lamp, 7,8 ... Rolling roll, 9 ... Long sheet, 11 ... Sheet unit, 12 ... High frequency molding machine , 13 …… Lower mold, 14 …… Upper mold, 15,16 …… Electrode plate, 19…
... skin layer, 20 ... decorative mall.

Claims (1)

[Claims] 1. A long sheet in which a granular pellet mainly composed of an expandable resin is preheated and then continuously passed between rolling rolls so that an appropriate space is maintained between the granular pellets. After preparing and cutting the long sheet into a predetermined size, it is filled in a lower mold having heat resistance and a non-conductive material and an upper mold made of a metal having high thermal conductivity, and A method for producing a decorative molding for automobiles, characterized in that the sheet is subjected to high-frequency heat treatment in a mold and melt-molded.