JP2549563B2 - Injection mold - Google Patents

Description

TECHNICAL FIELD The present invention relates to an injection molding die for producing a synthetic resin multicolor molded product, and particularly to an injection molding die that guarantees highly reliable operation. Regarding

[Prior art]

As is well known, injection molds are used in the field of plastic molding. This injection molding will be described by taking a magnetic tape cassette as an example. As is well known, magnetic tape cassettes used for audio and video are usually formed by injection molding the upper and lower cassette halves, and the upper and lower cassette halves are used to form the case body.
Similarly, it has a structure in which a pair of hubs made by injection molding are rotatably incorporated and held in a state in which a magnetic tape is wound.

The upper and lower cassette halves are generally made by injection molding a plastic material such as ABS resin. That is, it is molded by injecting a molten material through an injection hole (gate) such as a direct gate or a submarine gate into a space corresponding to the shape of a cassette half which is usually formed by two molds. Then, the cassette half molded product formed by cooling and solidifying the material filled in the mold space is taken out from the mold.

Further, the upper and lower cassette halves are entirely made of a light-transmissive material so that the winding state of the magnetic tape can be visually confirmed from the outside, or are transparent or semi-transparent as shown in FIG. The window 6 is provided in the opaque cassette half 2, and the window 6 is formed in a desired shape for the purpose of improving the design effect of the case body.

Conventionally, the window portion 6 has a window member formed separately from the frame portions of the cassette halves 3a and 3b.
It was constituted by adhering to a and 3b with an adhesive or ultrasonic welding. However, in this case, since the window member molding and bonding steps are required, not only the productivity is not good, the strength is not so high, and further the design is restricted. A manufacturing method by color molding (generally two-color molding) is often used. In particular, when the materials of the outer surface of the cassette and the inner surface of the cassette are overlapped, multicolor molding, which is excellent not only in appearance but also in quality, is an effective means.

Generally, there is a mold rotation method or core back method for multicolor molding, but the former has to rotate the entire mold, resulting in poor cycleability and relatively low productivity. The latter core back method is adopted as the most general method.

Double layer type cassette half by the core back method
The manufacturing process of 3a and 3b will be described with reference to FIG.

4. FIG. 4 is a schematic sectional view of a main part of the cassette half molding die corresponding to the section AA of the audio compact cassette shown in FIG.

As shown in FIG. 4, the core back injection molding die includes a fixed die 20 (also called a core side die) and a movable die.
22 (also referred to as mold on die side), slide core 26 provided in sliding hole 24 of fixed die 20, slide core 30 provided in sliding hole 28 of movable die 22 (because it is on the cabinet side) It may be referred to as a slide cabinet, but in the present specification, it is unified with a slide core). In order to mold the upper and lower cassette halves 3a and 3b on the mating surfaces of the fixed mold 20 and the movable mold 22, first, the slide cores 26 and 30 are arranged so as to come into contact with each other, and the primary mold is formed. Space 32
Are formed.

Then, for example, an opaque resin is injected and injected into the primary mold space 32 by a gate (not shown). The slide cores 26, 30 are held in a state of being brought into contact with each other by, for example, hydraulic drive means 34, 35. After that, the slide cores 26 and 30 are retracted to form a new space, and, for example, a transparent resin is injected. At this time, in particular, the slide core 30 applies a relatively large injection pressure along the sliding direction to the space wall surface 30.
Since it is received by a, the hydraulic control of the hydraulic drive means 35 causes a displacement in the sliding direction.
Since the slide core 26 receives the injection pressure in the direction perpendicular to the slide direction, it does not cause a problem as much as the slide core 30. Therefore, in the conventional case, a recessed structure 30b is formed on the side surface of the slide core 30 or the shaft supporting the slide core 30, and a wedge-shaped protruding member 40 that can be fitted into the recessed part 30b is provided. Stop devices are known. Further, although not shown, a configuration is also known in which an angular pin or a stopper block is used to move or stop the slide core 30.

[Problems to be solved by the invention]

However, with the above-mentioned conventional structure, a hooking structure is provided on the slide core 30 or a sliding portion such as a shaft holding the core 30, or in the case of an angular pin, the slide core is fitted. In addition to the complicated structure of the mold due to such a structure, it is difficult to obtain the positioning accuracy unless the constituent members are accurately configured.

Therefore, an object of the present invention is to solve the above-mentioned problems, and to provide an injection molding die that is configured to accurately move a slide core, guarantee the accuracy of a molded product for a long time, and have excellent maintainability. It is in.

[Means for solving the problem]

The above object of the present invention is to provide an injection molding die including a slide core having a surface for receiving an injection pressure of a molten resin injected into the die space in a slide direction, wherein the slide core forms the die space. A side wall opposite to the side where the concave and convex portions are formed, and a support block having a holding step portion that can be fitted into the concave and convex portion is arranged so as to abut against the rear wall of the slide core. At the same time, the support block is movably held in a direction orthogonal to the slide core moving direction, and the movement of the support block moves the contact position between the uneven portion and the holding step portion by the amount of the unevenness. This can be achieved by an injection molding die characterized in that the slide core is allowed to be positioned.

[Embodiment]

Hereinafter, the molding of the cassette half of the magnetic tape cassette according to the embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 and 2 are cross-sectional views showing a cassette half molding die of a magnetic tape cassette. A magnetic tape cassette composed of a cassette half molded by this mold has substantially the same structure as the magnetic tape cassette 1 shown in FIG. Note that, in FIGS. 1 and 2, the same components as those in FIG. 4 are designated by the same reference numerals.

The injection molding die of this embodiment includes a fixed die 20, a movable die 22, a slide core 26 provided in a sliding hole 24 of the fixed die 20, and a movable die 22 as shown in FIG. It is composed of a slide core 30 provided in the sliding hole 28. The fixed mold
On the mating surface between 30 and movable mold 22, cassette halves 3a, 3
In order to mold the window portion 6 of b, the slide cores 26, 30 are arranged so as to project and come into contact with each other to form a primary mold inner space 32. Although not shown, the space inside the mold
A gate for injecting and injecting an opaque resin and a gate for injecting and injecting a transparent resin are appropriately provided in 32.

The characteristic configuration of this embodiment is that the support plate 50 is provided on the side opposite to the side where the slide core 30 forms a mold space.
A back surface portion 47 is provided through the back surface portion 47, and an uneven portion having alternating recesses 48 and projections 49 is formed on the back wall of the back surface portion 47.
A support block 41 is provided behind the back surface portion 47, and the support block 41 is provided with a holding step portion composed of a concave portion 42 and a convex portion 43 that can be fitted into the concave and convex portion. is there.

The support block 41 is held in the slide hole 44 so as to be movable along the slide support surface 44a in the direction (Y direction) orthogonal to the slide core moving direction (X direction).
This movement is performed by the hydraulic drive means 46 via the shaft 45. By moving the support block 41,
The slide core 30 can be moved from the state where the convex portions 43 and 49 are in contact with each other to the position where the concave and convex portions are fitted together. The movement of the slide core 30 depends on the movement of the support plate.
This can be appropriately performed by the hydraulic drive means 51 attached to 50.

In order to form the cassette half body 2 with the mold having the above-described structure, first, the convex portions 3 and 9 are brought into contact with each other, and only the hydraulic drive means 34 is operated. The fixed mold 20 and the movable mold 22 are fitted together. At this time, the hydraulic means 51 is free, and the positioning of the primary mold space 32 is determined by the support block 41. Then, an opaque primary injection resin is injected and injected into the space 32 in the primary mold. The injected primary injection resin is molded into a shape defined by the fixed mold 20, the movable mold 22, and the slide cores 26 and 30.

After the primary injection resin is substantially solidified, the slide cores 26 and 30 are retracted in the sliding holes 24 and 28 as shown in FIG. 2 in order to mold the window portion 6 and the cassette surface portion. To form the window space 36, but prior to this, by operating the hydraulic means 46 and pulling the support block 41 (right direction in the figure), the convex portions 43 and 49 are in contact with each other. To the position where the concavities and convexities fit together,
After that, the hydraulic means 51 is operated to operate the slide core.
Move 30 so that the mold space expands, and move to the secondary mold space.
33 is formed. The positioning of the secondary mold space 33 is also performed extremely accurately by the support block 41. Then, a transparent secondary injection resin is injected and injected into the secondary mold space 33 so that the inside of the cassette can be seen through.
46 and forming the cassette surface.

Here, the cassette half body 2 molded by primary injection and the window portion 6 molded by secondary injection are
It is welded by heat and injection pressure at the time of the next injection molding to form an integrally molded product. Then, when the injection material filled in the mold space cools and solidifies, the movable mold 22 opens, and the cassette half molded product is taken out of the molding mold.

In this embodiment, by moving the support block 41 at a right angle to the core moving direction to change the contact position between the core step portion and the holding step portion, either of the primary or secondary metal Since the mold space size, in other words, all the dimensions in the case thickness direction can be determined by one block, the mold space is simply formed by the accurate dimensions of the support block 41, which is easy to obtain the dimensional accuracy in the block, and the precision of the molded product is improved. In addition, since the block 41 is a strong member, the precision of the molded product can be guaranteed for a long period of time and the maintainability is excellent.

In the above embodiment, the two-color molding is described, but the present invention is not limited to the two-color molding, and can be applied to the multi-color molding more than that. In this case, for example, if the support block 41 is configured to be movable in two directions along the sliding support surface 4a, and the contact position between the core step portion and the holding step portion is changed three times. Good.

In the embodiment, the support block 1 is configured to slide in the sliding hole 44,
The present invention is not limited to this, and may be configured to slide on another block provided outside the mold body.

In the above embodiment, the mold for the cassette half of the magnetic tape cassette is described, but the present invention is not limited to the magnetic tape cassette, and the injection material is injected into the space inside the mold to form a multicolor injection molded product. Needless to say, various injection molds can be used as long as they are used.

〔The invention's effect〕

As described above, the injection-molding die of the present invention is an injection-molding die including a slide core having a surface that receives the injection pressure of the molten resin injected into the mold space in the slide direction. The slide core has a core step portion formed on a rear wall opposite to the side forming the mold space, and a support block having a holding step portion that can be fitted into the core step portion is a slide block of the slide core. Since the support block is arranged so as to come into contact with the rear wall, and the support block is movably held in a direction orthogonal to the slide core moving direction,
Even if the injection pressure is large, the slide core can be positioned safely and accurately, and the movement of the support block moves the abutting position of the core step portion and the holding step portion so that the slide core 2 Since the positioning is performed more than once, the support block is moved at a right angle to the core moving direction to change the contact position between the core step portion and the holding step portion. Any of the mold space dimensions, in other words, all dimensions in the case thickness direction can be determined by one block, the mold space can be accurately formed by the accurate dimensions of the support block, and the precision of the molded product can be improved. In addition, since the support block is a sturdy member, the precision of the molded product can be guaranteed for a long period of time, and the injection molding is highly reliable with excellent maintainability. It is possible to provide a mold.

[Brief description of drawings]

1 and 2 are sectional views showing a cassette half molding die of a magnetic tape cassette according to an embodiment of the present invention, FIG. 3 is a plan view of a magnetic tape cassette, and FIG. 4 is a conventional magnetic tape. It is sectional drawing which shows the cassette half mold of a cassette. (Reference numeral in the figure) 1 ... magnetic tape cassette, 2 ... case body, 3a, 3b ... cassette half, 4 ... hub, 5 ... magnetic tape, 6 ... window, 20 ... fixed mold, 22 …… Movable mold, 24,28 …… Sliding hole, 26,30 …… Slide core, 32 …… Primary mold space, 33 …… Secondary mold space, 34,46,51 …… Hydraulic pressure Drive means 41 ... Support block 42, 48 ... Recessed portion, 43, 49 ... Convex portion, 44 ... Sliding hole, 44a ... Sliding support surface, 45 ... Shaft, 47 ... Rear portion, 50 …… Support plate, PL …… Parting line.

Claims (1)

(57) [Claims] 1. An injection molding die comprising a slide core having a surface for receiving an injection pressure of a molten resin injected into the die space in a slide direction, wherein the slide core forms a side of the die space. An uneven portion is formed on the back wall on the side opposite to, and a support block having a holding step portion that can be fitted into the uneven portion is arranged so as to abut the back wall of the slide core, The support block is movably held in a direction perpendicular to the slide core moving direction, and the movement of the support block allows the contact position between the uneven portion and the holding step portion to move by the size of the unevenness. A mold for injection molding, characterized in that it is configured to position the slide core.