JPH0357854B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a synthetic resin container for a videotape cassette, which has a substantially rectangular parallelepiped shape and has an open opening on one side.

Such synthetic resin containers with small volumes can be molded into three-dimensional shapes by direct injection molding, but in the case of cases that store items over a certain volume, such as tape cassettes for video tape recorders, Since it is impossible to perform three-dimensional molding by direct injection molding, a method is used in which a box is manufactured from a spread plate.

Conventionally, the development plate of such synthetic resin containers has been made by cutting a synthetic resin flat plate of a certain thickness extruded into a long length from a T-die to make a plate of a certain size, and then cutting the plate at the crease (hereinafter referred to as "K-line"). )
They were produced by compression shaping or cutting, punching out the notches, and in some cases embossing the surface. This conventional manufacturing method requires a large number of man-hours and is inefficient, has a high rate of defective products, and has disadvantages in terms of cost and industrial waste generation because cutting allowances and notch allowances are discarded. Ta.

The present invention eliminates the drawbacks of the conventional manufacturing method as described above, eliminates the need for cutting, punching, and embossing, reduces the number of man-hours, and produces a synthetic resin for videotape cassettes that is efficient, cost effective, and environmentally friendly. The purpose of the present invention is to provide a method for manufacturing containers.

The object of the present invention is to provide a container manufacturing method in which a developing plate having a cross section and a notch is created and the same is manufactured into a box, in which the thickness of the developing plate ranges from 0.5 cm to several centimeters.
mm, and the wire section is relative to the thickness of the expansion plate.
This is achieved by a method for manufacturing a synthetic resin container for a videotape cassette which is 30% or more thinner and is characterized in that the developing plate is made by injection molding with two or more injection ports.

Hereinafter, the present invention will be explained in more detail with reference to the accompanying drawings.

In the present invention, a synthetic resin container 1 for a videotape cassette in the shape of a rectangular parallelepiped with an open opening on one side as shown in FIG.
Alternatively, it can be manufactured by forming a developing plate 2' shown in FIG. 3 into a box.

In FIGS. 2 and 3, the unfolding plate 2 or 2' has a front part 4 or 4'; a rear part 5 or 5';
Left side 6 or 6'; Right side part 7 or 7'; Bottom part 8 or 8'; Left side overlapped part 9 or 9'; Right side overlapped part 10 or 10'; flap 11, 11a or 11', 11'a By forming these into a box, a synthetic resin container 1 for a videotape cassette as shown in FIG. 1 is formed. In Fig. 1, the correspondence of each part of the unfolding plate in Fig. 2 is indicated except for the flaps 11, 11a and the highlighted line part 12, and the correspondence of each part of the unfolding plate in Fig. 3 is also in accordance with this. .

Conventionally, a synthetic resin container 1 for a videotape cassette as shown in the first example is made of a synthetic resin flat plate of a certain thickness that is extruded into a long length from a T-die in the case of storing an item larger than a certain volume. After cutting to make a rectangular plate with the cutout area marked with diagonal lines in FIG. The cutout parts 13, 14, 15, 16 or 13', 14', 15', 16' are punched out, and in some cases, the front part 4 or 4' is stamped to create a development plate. , this was made into a box.

According to the present invention, the developing plate 2 or 2' as shown in FIG. A synthetic resin container 1 for a videotape cassette as shown in FIG. 1 is produced by injection molding with unevenness on the front surface, etc., and by forming the container into a box.

In the method of the present invention, various thermoplastic resins can be used as the synthetic resin for injection molding.
In particular, polyolefin thermoplastic resins, polystyrene thermoplastic resins, and ABS thermoplastic resins are suitable in terms of cost, manufacturing accuracy, and dimensional stability. These thermoplastic resins contain various additives such as foaming agents, white pigments (titanium oxide, talc, mica, calcium carbonate, clay, etc.), various carbon blacks, various metal powders (aluminum powder, tin powder, etc.), and dyes. agents can be added.

Furthermore, when injection molding is performed in the method of the present invention, it is desirable to provide an injection port for the molten thermoplastic resin not only at one location but at a plurality of locations. By doing so, the flow of the resin improves during injection molding, and it is possible to prevent the occurrence of a boundary line where resin flows converge, which is called a weld line. These inlets have cutouts 13, 14, 15, 16 or 13',
It is preferable to provide it at portions 14', 15', and 16'.

Furthermore, by adding 0.2 to 5% by weight of a silicone compound such as dimethylsiloxane to the thermoplastic resin, fluidity during molding, moldability, mold releasability, and slipperiness after molding can be improved. Additionally, by adding an antistatic agent to the thermoplastic resin, it is possible to make it difficult for dirt and dust to adhere to the container, or by adding a foaming agent to the thermoplastic resin, the appearance of the container can be changed to improve its feel and make it lighter. It may also be optionally possible to do so.

When manufacturing a synthetic resin container 1 for a videotape cassette as shown in FIG. 1 by the method of the present invention, a developing plate 2 or 2' as shown in FIGS.
Preferably, the cross-sectional shape is as shown in FIG. 4 or 5. Plate thickness t ranges from about 0.5mm to several
Generally, the thickness is up to about mm, and the wire portion is 5% of the plate thickness t.
By desirably making it thinner by 30% or more, it becomes easier to form a box.

Emboss treatment, grooves, and recesses are selectively applied to the outer or inner surfaces of the front part 4 or 4'; back part 5 or 5', etc. to improve the appearance and ease of handling. . In conventional manufacturing methods, these were performed by embossing, but in the method of the present invention, these surface treatments can also be performed during injection molding.

Next, in order to further clarify the effects of the present invention, examples are listed below.

(1) A mold for injection molding of a developing plate as shown in Fig. 2 was prepared. So that the dimensions of the expansion plate are as follows:
Designed the mold. There were two injection ports in the notches 13 and 14.

Vertical and horizontal dimensions of the expansion plate: The longest part is 247mm x 237mm Thickness of the expansion plate: 0.8mm Dimensions of the lined part: Width 1.5mm, depth 0.25mm Cross-sectional shape of the lined part: As shown in Figure 4 Notch Dimensions of 13 and 14: Length approximately 70 mm, width 20 mm Dimensions of notches 15 and 16: Polygon with the longest part being 37 mm x 28 mm (2) Using this mold, molten thermoplastic resin with the following composition was released. Molded: Polypropylene resin manufactured by Mitsubishi Yuka Co., Ltd., grade
NO, MS630...95% by weight Dimethylpolysiloxane manufactured by Shin-Etsu Silicone Co., Ltd., brand name KF-96...1% by weight Titanium oxide...4% by weight (3) Assemble the injection molded development plate 2 and separate the overlapping parts. Welded using an ultrasonic welding machine to obtain approximate dimensions.
A case for a videotape cassette measuring 192mm x 105mm x 28mm was manufactured.

Conventional cutting and cutting when the number of boxes manufactured is 300,000 pieces.
Compared to a manufacturing method that includes a punching process, the manufacturing cost is reduced by 50%, and the incidence of defective products is 11% lower than that of the conventional method.
%, it was 1% in the method of the present invention.

According to the method of the present invention, the number of man-hours is reduced as described above, which lowers manufacturing costs and stabilizes the process.
Significant effects can be obtained, such as improving quality in terms of appearance, precision, and surface finish, automating work, and reducing industrial waste.

The present invention is not limited to the embodiments, and can be widely applied, for example, as shown below.

(1) The shape of the expansion plate is not bilaterally symmetrical; for example, the shape of the front part and the shape of the back part may be different.

(2) Even if the thickness of the side part is the same as the remaining thickness of the wire part, the strength can be maintained by overlapping.

(3) The shape of the notch can be various shapes such as rectangle, square, trapezoid, semicircle, semiellipse, equilateral triangle, isosceles triangle, and arrow shape.

(4) The remaining thickness of the wire part may be partially thickened to improve the flow of resin during injection molding.

(5) The inner surface of the mold can be processed so that the inner and outer surfaces of the case have silky grains, sandy grains, rope grains, vertical stripes, horizontal stripes, lattice grains, fine-grain surface textures, etc.

(6) For injection molding, the thermoplastic resin can be a copolymer or a mixed resin of two or more thermoplastic resins.

(7) Thermoplastic resins contain 1 color pigment or color dye.
A species or multiple species can be added.

(8) After the development plate is injection molded, printing and labeling processes are selectively added before and after the box manufacturing process.
Marks and characters can be attached.

[Brief explanation of drawings]

FIG. 1 is an external view of a synthetic resin container for a videotape cassette manufactured according to the present invention, FIGS. 2 and 3 are plan views of an embodiment of a developing plate, and FIGS. 4 and 5 are A in FIG. - on side B or in Figure 5;
FIG. 3 is a cross-sectional view of the developed plate along plane A'-B'. 1...Synthetic resin container for video tape cassette, 2, 2'...Development plate, 12, 12'...K line section, 13, 14, 15, 16, 13', 14', 1
5', 16'... Notch.

Claims (1)

[Claims] 1. In a container manufacturing method in which a developing plate having a diagonal line part and a notch part is created and the same is manufactured into a box, the thickness of the developing plate is approximately 0.5 mm to several mm, and the diagonal line part is the same as the developing plate. 1. A method for producing a synthetic resin container for a videotape cassette, which is 30% or more thinner than the plate thickness, and the developing plate is made by injection molding with two or more injection ports.