JPS59209126A - Outsert molding method - Google Patents

Abstract

PURPOSE:To enable the removal of a runner even if the rigidity of a metal plate is low, with respect to the holding force of the runner into a mold, by forming the runner so as to provide a cross-sectional area with a taper wherein one side surface of said runner is exposed to a parting face and the parting surface side thereof comes to a small diameter. CONSTITUTION:A molten resin passes the runner 2 on a metal plate 1 to be formed into a resin structure 3 and the runner 2 has an inverted tapering cross sectional shape. That is, the runner 2 has such a cross-sectional area with a taper that one side surface thereof is exposed to the parting face P of a movable mold 7 and the parting surface side thereof comes to a small diameter. When the movable mold 7 is opened from a fixed mold 6 after the resin is solidified and a protruding plate 10 is moved to eject a molded article by an ejector pin 8, the runner 2 remains in the movable mold 7 and the outsert molded article is taken out. Thereafter, the runner 2 is pushed out from the interior of the mold by moving the protruded plate 10 and taken out after separated from the outsert molded article.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to an outsert molding method, particularly for precision parts,
For example, the present invention relates to an outsert molding method that is optimal as a molding method for a chassis for a video tape recorder (hereinafter referred to as a VTR).

[Background of the invention]

Conventionally, as this type of outsert molding method, for example, the first
It is known that the front and back surfaces are shaped as shown in FIGS. That is, immediately after molding, in addition to the resin structure 3 outsert to the metal plate 1, the spool 5 and the runner 2 extending between the resin structures 3 remain, and these are removed later.

This is because, as shown in FIG. 3, the runner 2 is formed into a shape that is wide on the metal plate 1 side and is easily cut out.

By the way, outsert molded products as ultra-precision parts,
In addition to dimensional accuracy during molding, it is also required to prevent deformation such as warping of the molded product due to residual stress in the resin part.
It is undesirable to leave the above-mentioned runner in the form of a metal plate. Therefore, it was considered to remove the runner on the metal plate when opening the mold, and this method was published in Japanese Patent Laid-Open No. 55-1
As shown in Japanese Patent No. 39239, a hole is drilled in a metal plate, and when the mold is opened, a knockout pin is passed through the hole and brought into contact with a launch, pushed up, and cut through the notches at both ends of the runner, As shown in Japanese Unexamined Patent Publication No. 55-99823, there is a method of removing the runner using a so-called submarine gate, in which a launch is inserted into a mold. However, the former requires a hole on the metal plate for the knockout pin to pass through, which reduces the rigidity of the metal plate. Not applicable to outserts. Also, an extra step of drilling holes in the metal plate is required. On the other hand, the latter cannot be applied because if the height of the resin component in contact with the metal plate is lowered in order to reduce the thickness of the VTR, the resin in the submarine gate will not come out. Furthermore, it is generally difficult to provide a submarine gate in a launch where the resin components are close to each other, and this method cannot be applied.

[Purpose of the invention]

The object of the present invention is to provide a metal plate using a metal plate with low rigidity.
To provide an outsert molding method which enables lunch removal even if the height of a resin component in contact with a metal plate is low and can obtain an outsert molded product with excellent dimensional stability.

[Summary of the invention]

In the outsert molding method according to the present invention, a plurality of cavities for resin molding into a metal plate are formed on the parting surface of a mold consisting of a fixed mold and a movable mold, and a runner extending between the cavities is used to control the molding during mold release. In the outsert molding method in which the runner is separated from the product by the holding force within the mold, the holding force within the mold is such that one side of the runner is exposed on the parting surface and the runner has a small diameter on the parting surface side. This is caused by creating a tapered cross-sectional shape.

By using this method, even when outsert a resin structure having a flange portion with a height of one stage or less on a metal plate with a thickness of 1 mm or less and low rigidity, such as a plate such as aluminum, each This can be applied to remove runners that connect flange parts.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described with reference to FIGS. 4 to 23.

Note that this embodiment is applied to a VTR chassis.

4 and 5 show the application areas of the outsert molding method according to the present invention, showing the front and back surfaces of a VTR chassis in which a large number of resin structures 3 and holes 4 are formed on a metal plate 1. are shown respectively. Connect some of the resin structures 3 and place two more runners on the metal plate 1 as shown by the imaginary lines A-G.
' remains. In other words, the runner marks 2' are the areas where the runners are laid during molding and are affected by the heat of the resin. However, the remaining 2' of this runner, as described later,
Since the runner is removed during mold release, the accuracy and functionality of the molded product are not affected at all.

FIGS. 6 to 12 are enlarged views showing each of the lunch ports 2' of sections A to G in FIGS. 4 and 5, respectively.

In addition, in FIGS. 6 to 12, the thickness of the metal plate 1 is 1
The thickness of the flange portion of the resin structure 307 is 0.0 mm.
5-11aI.

FIGS. 13 to 16 are schematic enlarged views of the outsert molding method according to this embodiment.

As shown in FIG. 13, the mold is composed of a fixed mold 6 and a movable mold 7, between which a metal plate is sandwiched and a cavity 20 for molding a resin structure is formed. The molten resin passes through the runner 2 on the metal plate 1 via the spool 5, enters the cavity 20, and forms the resin structure 3 on the metal plate 1. Here, as shown in FIG. 14, the runner 2 on the metal plate 1 has a cross-sectional shape that is reversely tapered, which is different from the conventional one (FIG. 3). That is, the runner 2 has a tapered cross-sectional shape with one side exposed to the parting surface P of the movable die 7 and having a smaller diameter on the parting surface side. Note that the taper is 90° to 135° with respect to the parting surface P.
It is an angle of °.

After the resin has solidified, as shown in FIG.
When the movable mold 7 is opened from the fixed mold 6 and the protruding plate 10 is moved to eject the molded product from the ejector bin 8, the runner 2 remains in the movable mold 7 and only the Actcert molded product is taken out. . Thereafter, as shown in FIG. 16, if the protruding plate 1o is further moved and the runner 2 is extruded from inside the mold with a force greater than the resin deformation load, the runner 2 is completely removed from the movable mold 7 as an outsert molded product. It is taken out in a separated state.

FIGS. 17 and 18 show the front and back surfaces of the outsert molded product taken out, respectively. As shown in Figure 18,
At the location where the runner 2 was, a p-runner mark 2' remains due to the heat of the high-temperature resin, but this does not affect the accuracy or performance of the molded product at all. The remaining 2" contact points with the runner 2 are located at the contact points between the metal plate 1 and the resin structure 3, as shown in FIG. 19. This part does not affect the dimensional accuracy of the resin structure at all. be.

Figures 20 to 23 compare the amount of deformation and deformation over time of the metal plate of a conventional outsert molded product in which the runner 2 is present and a molded product according to this embodiment in which the runner 2 is removed. This is what is shown.

In Figure 20, the injection pressure is 1200 kgf/(1)2,
FIG. 2 is a characteristic diagram showing how much the deformation of the aluminum plate differs between when there is a runner 2 on the aluminum plate and when there is no runner 2 on the aluminum plate when polyacetal resin is Actocert molded on an aluminum plate with a thickness of 1 m. . Here, the broken line ■ represents the amount of deformation when the runner remains.
indicates the amount of deformation when the runner is removed. As shown in the figure, it was confirmed that the amount of deformation was smaller in the molding method according to this example in which the runners were removed than in the conventional method in which the runners remained.

Figure 21 shows 1200 kgf/
FIG. 2 is a characteristic diagram showing a comparison of the amount of deformation with and without a launch on a metal plate when outsert molding is performed on an aluminum plate with a thickness of 1 m at an injection pressure of crn2.

The broken line ■ indicates the case where the runner remains, and the broken line ■ indicates the case where the runner has been removed. In this case as well, the amount of deformation is small in the case of this embodiment in which the runner is removed.

Furthermore, FIG. 22 is a characteristic diagram showing the deformation of the molded product over time when the polyacetal resin was outsert molded onto an aluminum plate and inserted into a constant temperature oven at 90C.

The broken line ■ indicates the case where there is a lunch, and the line ■ indicates the case where there is no runner. From this figure, it can be seen that after 60 days, the outsert molded product with the runner was deformed to the extent that the runner was cut off.

Furthermore, FIG. 23 is a characteristic diagram showing the deformation of the molded product over time when an ABS resin molded onto an aluminum plate was inserted into a constant temperature bath at 90C. The broken line (■) shows the case where there is a runner, and the broken line (2) shows the case where there is no lunch, and the same tendency as described above is observed.

According to the outsert molding method according to this embodiment, the metal plate 1
Since the runners 2 are removed from both sides, molding with excellent dimensional stability can be achieved.

This is particularly effective when an aluminum plate of 1 ma or less is used to reduce the size and weight of the molded product. Moreover, due to the thinning of the molded product 3, the thickness of the 7 flange portions of the resin structure 3 is 0.5
Even if the cage is closed, the launch can be removed, so dimensional instability such as tilting of the resin structure 3 does not occur, and it can be easily carried out even when the distance between the structures is small.

In the above embodiment, the case where the launcher is arranged movably has been described, but the runner may be arranged at a fixed amount. For example, the present invention can be applied by making Venus into a three-plate type.

Further, in the above example, a case where ABS resin and polyacetal resin were applied was shown, but the examples are not limited to these, but include polypropylene, acrylonitrile/acrylic rubber/styrene copolymer (AAS resin), polystyrene, acrylonitrile/ethylene propylene rubber, Styrene copolymer (A
BS resin), nylon 6, nylon 66, nylon 12
, thermoplastic resins such as polysulfone, polyethersulfone, polyferrylene sulfide, polyphenylene oxacite, thermosetting resins such as epoxy resins and unsaturated polyester resins, and inorganic fillers or organic fillers added to these resins. Of course, various other materials can be used.

〔Effect of the invention〕

As described above, according to the outsert molding method of the present invention, an outsert molded product with good dimensional accuracy and no launch can be easily obtained and has little deformation over time. Since it can be taken out individually and completely from the mold, outsert molding can be automated. This is particularly effective when the size of the resin molded product is small and the distance between the molded products connected by runners is small.

[Brief explanation of the drawing]

1 and 2 are perspective views showing a molded product based on the conventional method from the front and back, FIG. 3 is a partial sectional view taken along the line K- in FIG. 2, and FIGS. This shows an example.
FIG. 4 is a perspective view showing the surface shape of the chassis, which is a molded product;
Figure 5 is a perspective view showing the shape of the back side, Figure 6 is A of Figure 2.
Figure 7 is an enlarged view of part B of Figure 1. Figure 8 is an enlarged view of part B of Figure 1.
Figure 9 is an enlarged view of part C in the figure. Figure 9 is an enlarged view of part D in Figure 2.
The figures are an enlarged view of section E in FIG. 1, FIG. 11 is an enlarged view of section F in FIG. 1, FIG. 12 is an enlarged view of section G in FIG. Figure 14 is a cross-sectional view taken along line H-H in Figure 13, Figure 15 is a cross-sectional view showing the middle process of molding, Figure 16 is a cross-sectional view showing the final stage of molding, and Figures 17 and 18 are outserts, respectively. FIG. 19 is a perspective view showing the contact points between the launch and the resin structure, and FIGS. 20 to 23 are characteristic diagrams showing various product characteristics based on the present invention. 1... Metal plate, 2... Runner, 2'... Runner back, 2"... Contact point between runner and molded product, 3...
Resin structure, 5... Suguru, 6... Fixed type, 7.
...Movable type, P...Parting surface, 20...Cavity. Agent Patent Attorney Tatsunosuke Unuma l Country No. 2 Figure # 3 Figure Heat 4 Item 5 Cause 6 Item 7 Marokyo 8 Item 9 Mouth 10 No. 11 Figure 2 / 2 Figure 75 Qin / 6 Country No. 77 Figure $20 Figure 21 Hard 2z heating fT-ship (B) Figure 23 For heating pieces (Yoji)

Claims (1)

[Claims] 1. A plurality of cavities for resin molding onto a metal plate are formed on the parting surface of a mold consisting of a fixed platen and a movable mold, and the runners extending between the cavities are held in the mold during release. In the outsert molding method, in which the launch is separated from the product using The Actosart molding method is characterized by the generation of