JPH0520260B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a vacuum forming method for plastic car models, etc., and particularly to a vacuum forming method for an undercut portion that occurs in a front bumper portion.

(Prior art) In the vacuum forming method, as shown in Fig. 2 a, b, and c, a thermoplastic sheet a is fixed on a mold b, and the sheet is softened by heating with a heater c and then sucked into the mold using a vacuum to form the sheet. Because the molding machines, molds, etc. are inexpensive,
Suitable for molding large products and thin containers. Figure 2 shows an example of the drape method, in which a convex mold b is used to push up the heated and softened sheet a to perform preliminary stretching (Figure 2b), and then it is sucked into the mold using a vacuum. (Fig. 2c). Usually, plastics such as hard vinyl chloride resin, high-impact polystyrene, and ABS resin are used.
It is used to mold signboards, electric refrigerator inner boxes, ice cream cups, egg and tofu containers, etc.

Now, in a mold without an undercut portion, such as mold b in FIG. 2, it is easy to release the molded product.
However, when taking out the product from the mold, if there is a protrusion or a recessed part in the opening/closing direction of the mold, the product cannot be taken out from the mold.

However, even if there is an undercut, if the constituent material is highly elastic, the amount of undercut is small, and the shape is easy to release, the product may be forcibly released from the mold (forcibly removed). can be done.

However, when vacuum forming a model car, etc., if the front bumper portion is made to closely resemble the real thing, this portion will have an undercut structure that is difficult to release from the mold.

A slide core method is known to facilitate the release of the undercut portion. However, diagonal linear protrusions always occur on the sliding surface of the slide core, and in the case of model cars, lines that do not exist in the actual product appear, which poses a fatal problem.

For this reason, although we would like to make it resemble the real thing, we had no choice but to sacrifice the resemblance to the real thing and change this part to make it easier to cut out the mold.

(Problems to be Solved by the Invention) In view of the problems of the prior art, when vacuum forming a model car, we have developed a method that can be vacuum formed to almost resemble the real model, even if the structure has a noticeable undercut, such as the front bumper. The purpose is to provide a vacuum forming method.

(Solution by the Invention) In a vacuum forming method for model cars using vacuum forming, the parting line is set just above the upper edge of the front bumper, the extension of the parting line is made to fit within the wheel arch, and the lower part of the parting line is made to fit within the wheel arch. As a split mold that can be moved to the rear of the model car, it can be easily released even if the undercut is tight.

(Example) Vacuum forming of a model car will be described below.
In Fig. 1, A is a molded product of a model car formed by vacuum forming. 1 is the front bumper, which extends forward. 2 is the rear bumper, which also extends to the rear. 3 is a front arch, and 4 is a rear arch. These parts are vacuum formed, released from the mold, and then cut with a cutter. 1a and 2a are side extension lines of the upper edges of the front bumper 1 and the rear bumper 2. These extension lines are the rear end 1b or the front end 2, respectively.
b terminates in each arch 3 or 4.

Now, in such a model car, the side extension lines 1a and 1b of the bumper do not appear as clearly as shown on the left in the real thing, but in the present invention, among these extension lines, the upper edge of the front bumper 1 is Even if the extension line 1a appears to some extent, it does not pose a problem in terms of the appearance of the product as an extension of the front bumper, so the upper part of this line is used as a cutting line and the mold for molding is split into a split mold. The model car can be slid below this substantially horizontal parting line toward the rear of the model car (see the two-dot chain line in FIG. 1).

A split mold 5 is used as a parting line on the upper surface of the side extension line of the front bumper, and the lower part of the parting line is made slidable rearward on a surface plate 6 to facilitate mold release of the front part, but at the same time, the rear part is also molded. If the front part is released from the mold, it can also be released easily.

In the above explanation, the front part of the model car is made into a split type, but the rear part may of course be made into a split type.

The present invention was developed with the primary purpose of avoiding tight undercuts in the vacuum forming method for model cars. This method can be used in products where the resulting horizontal lines on the molded product do not significantly affect the appearance of the molded product.

(Effects) The upper surface of the side extension of the front bumper is made into a parting line, and the extension of the parting line is made to fit inside the wheel arch, and the lower part of the front of the model car is made into a split mold so that it can slide backwards. When vacuum forming, a nearly horizontal line appears on the front trim of the model car, but since it is an extension of the upper edge of the bumper, there is no problem with the design at all, and it is possible to create a model car with a structure that is very similar to the real thing. Can be vacuum formed.

[Brief explanation of the drawing]

FIG. 1 is a side view of a vacuum-formed product according to the present invention. FIG. 2 is an explanatory diagram of the vacuum forming method. In the figure; A...Model car molded product, 1...
...Front bumper, 1a...Side extension line, 1b
...Side extension line, 2...Rear bumper, 2a, 2
b...Side extension line, 3...Front arch, 4...
...Rear arch, 5...split type, 6...surface plate.

Claims (1)

[Claims] 1. In the vacuum forming method for model cars, the parting line is set just above the upper edge of the front bumper, the extension of the parting line is placed within the wheel arch, and the lower part of the parting line is directed toward the rear of the model car. A vacuum forming method for model cars characterized by a movable split mold that facilitates mold release of the undercut part.