JPH06143341A - Injection molding method of molded article having three layer structure and mold thereof - Google Patents

Abstract

PURPOSE:To obtain a mold, with which molding can be carried out in a short cycle at a low cost by a method wherein a molded article having three layer structure consisting of a first layer, a third layer and an intermediate layer pinched between the two layers is molded by injection molding. CONSTITUTION:The mold concerned consists of a first mold 1 for molding a first layer A, a third mold 5 for molding a third layer C and a second sliding mold 10, which is provided slidably between the molds 1 and 5 for molding an intermediate layer B. At the primary injection molding, by injecting molten resin in the cavity of the first mold 1 and in the cavity of the third mold 5 under the condition that the cavity 11 of the second sliding mold 10 is closed off so as to mold the first layer A and the third layer C. Then, at the secondary injection molding, the second sliding mold 10 is slid to the position at which the cavity 10 registers with the cavity of the first mold 1 and with the cavity of the third mold 5. Next, molten resin is injected into the cavity 11 of the second sliding mold 10 so as to mold the intermediate layer B.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a first layer, a third layer,
The present invention relates to an injection molding method for a three-layer structure molded article and a mold for molding the three-layer structure molded article including an intermediate layer between these layers by injection molding.

[0002]

2. Description of the Related Art Plastic products are used in a wide variety of ways, and there is also a need for a three-layer structure molded product having partially different physical properties or colors. The molded article S having such a three-layer structure generally has a first layer A, an intermediate layer B, and a third layer C as shown in (a) and (b) of FIG.
And 3 are injection-molded by different molds, and the contact surfaces of these layers A, B, and C are joined or welded with an adhesive to form a molded article S having a three-layer structure.

On the other hand, (a), (b) in FIG.
As shown in (c) each step, a pair of molds 4
A method of molding the third layer C by secondary injection molding using 0, 42 is also known. That is, the movable mold 4 is used in the first step.
0, the first layer A and the intermediate layer B, which have been previously formed in different molds, are sequentially inserted using the guide rod or the positioning rod 41, and the intermediate die 42 is clamped in the second step, and the third layer As shown in (b) in the step, the molten resin is injected from the nozzle 43 into the upper space of the inserted intermediate layer B through the runner 44 of the mounting plate 46 to form the third layer C, A method is also known in which the ejector 45 takes out the molded product S having a three-layer structure after waiting for cooling and solidification.

Furthermore, as shown in FIG. 6, a method of injection molding the intermediate layer B using a mold is also known. According to this method, the preformed third layer C is inserted into the cavity 51 of the movable die 50,
Similarly, the first layer A which has been previously formed is inserted thereabove and clamped with the intermediate die 54 as shown in (b). At this time, the flange A ′ of the first layer A is locked to the step portion 52 of the cavity 51, and the first layer A and the first layer
A space for molding the intermediate layer B is secured between the lower surface of the layer A and the lower surface. Therefore, when the molten resin is injected from the injection nozzle 53, the resin is injected into the space between the upper surface of the third layer C and the lower surface of the first layer A through the runner 55 and the gate 56 of the intermediate mold 54, and the intermediate layer B is molded. After cooling and solidification, as shown in FIG. 6C, the mold is opened and the ejector 57 removes the molded product S having a three-layer structure.

[0005]

As described above, the molded product S having a three-layer structure can be formed by the conventional method, but it has various drawbacks. For example, the first layer A, the intermediate layer B, and the third layer C are molded by different molds, and the contact surfaces of these layers A, B, and C are joined or welded with an adhesive to form a three-layer structure. In the method of forming a molded article of (3), three types of molds are required to mold each of these layers A, B, C, and there is a drawback that the cost of the mold increases. Further, an adhesive agent, a welding device, etc. are required, and the processing steps and the molding cycle are lengthened. Therefore, there is a disadvantage that the labor cost is also high.

On the other hand, the conventional molding method using a mold has the same drawbacks. That is, according to the method of injection molding the third layer C described with reference to FIG. 5, two molds for preforming the first layer A and the intermediate layer B are required, and the third layer C is further injected. A mold for molding is also required.
Moreover, since the first layer A and the intermediate layer B are not fused even when the third layer C is molded, the first layer A and the intermediate layer B are bonded or welded before or after the injection molding of the third layer C. There is a need.
Further, it takes time and effort to insert the first layer A and the intermediate layer B into the mold 40, and the molding cycle becomes long. Further, in the process of closing the mold, there is a defect that the position of the insert, that is, the positions of the first layer A and the intermediate layer B are deviated from each other, or they are separated from the mold, and thus a molding problem easily occurs. In addition, according to the method of injection molding the intermediate layer B described at the end, the intermediate layer B
When injection molding the intermediate layer B, the first layer A and the third layer
Since layer C is welded, there are no adhesion problems, but first
Since the layer A and the third layer C are molded respectively, and the intermediate layer B is molded, a total of three types of molds are required, and similarly, there is a drawback that the cost of the mold increases. If the number of molds is large, the molding cycle is long and the cost is high. Furthermore, there is a problem of trouble on the insert.
As described above, the conventional methods have the drawback that the molding cycle becomes long and the productivity is lowered. Therefore,
It is an object of the present invention to provide an injection molding method for a three-layer structure molded article which can be molded at low cost in a short cycle, and a mold for the same.

[0007]

In order to achieve the above-mentioned object, the invention of an injection molding method includes a first mold 1 for molding a first layer A, and a third mold 5 for molding a third layer C. In the primary injection molding, the cavity of the second slide mold 10 is used in the primary injection molding by using the second slide mold 10 that is slidably provided between these molds 1 and 5 and molds the intermediate layer B. In the state where 11 is closed, the molten resin is filled with the cavities 2 and 3 of the first mold 1.
It is injected into the cavity 6 of the mold 5 and the first layer A and the third layer C
And the second slide mold 1 in the secondary injection molding.
0 is the cavity 11 and cavity 2 of the first die 1
Then, the molten resin is slid to a position aligned with the cavity 6 of the third mold 5 and the molten resin is injected into the cavity 11 of the second slide mold 10 to mold the intermediate layer B. The invention according to claim 2 is the first mold 1 and the third mold.
A mold 5 and a second slide mold 10 slidably provided between the molds 1 and 5, for molding the first layer A on the first mold 1. The first cavity 2 has a third die 5 for forming a third layer C for forming a third layer C.
The cavity 6 and the second slide mold 10 have an intermediate cavity 11 and a through hole 12 for forming the intermediate layer B.
And a position where the cavity 11 of the second slide mold 10 is aligned with the cavity 2 of the first mold 1 and the cavity 6 of the third mold 5, and a through hole. 12 is configured to be slidable into the aligned position.

[0008]

The second slide mold 10 is slid to align the through hole 12 of the second slide mold 10 with the cavity 2 of the first mold 1 and the cavity 6 of the third mold 5. Then clamp the mold. When the molds are clamped, the cavities 2 of the first mold 1 and the cavities 6 of the third mold 5 are cut off by the second slide mold 10. The molten resin is injected into the cavity 2 of the first mold 1 and the cavity 6 of the third mold 5 by inserting, for example, a runner. Then, the cavity 2 of the first mold 1 forms the first layer A, and the cavity 6 of the third mold 5 forms the third layer C. Wait for cooling and solidification, loosen the mold, take out the runner as necessary, and use the second slide mold 10 with its cavity 11 as the cavity 2 of the first mold 1 and the cavity 6 of the third mold 5. Slide to the aligned position. Similarly, the mold is clamped and the molten resin is injected through the runner. The cavity 2 of the first die 1 and the cavity 6 of the third die 5 have already been injection-molded with the first layer A and the third layer C, so that the molten resin is used for the second slide die 10. The intermediate layer B is molded by being injected only into the cavity 11. The mold is opened after cooling and solidification, and the three-layer structure molded product S is taken out. The same operation is repeated thereafter for molding.

[0009]

EXAMPLES Examples of the present invention will be described below. As shown in FIG. 3, the three-layer structure molded article S molded according to this embodiment has a relatively large diameter first layer A and a smallest diameter third layer.
It is formed from a layer C and an intermediate layer B between these layers A and C. A through hole is formed in the center of the three-layer structure molded product S. Examples of molds for injection molding are
This is shown in FIG.

The mold according to this embodiment comprises a first mold 1 for molding the first layer A, a third mold 5 for molding the third layer C, and a first mold 1. The second slide mold 10 is provided so as to be slidable between the third mold 5 and the intermediate mold B, the middle mold 20, the mounting plate 30, the locate ring 31, and the like. Although not shown in the drawing, these molds 1, 5, 10, 20 are appropriately driven in a mold opening direction or a mold clamping direction by a conventionally known means. The first die 1 has a first layer A
Has a cavity 2 for molding. The cavity 2 has a shape of a through hole, and a stepped portion 3 having an enlarged diameter for forming the flange portion A ′ of the first layer A is formed above the cavity 2. The third mold 5 is provided with a concave cavity 6 for molding the third layer B, and an upward rod-shaped projection 3 is formed at a substantially central portion of the cavity 6. The rod-shaped projection 3 forms the center hole of the third layer C and also positions the runner of the intermediate mold 20 described later. The cavities 2 and 6 are tapered as a whole.

The second slide mold 10 has the same thickness as the intermediate layer B and is located between the first mold 1 and the third mold 5. Although not shown in the figure, for example, a die slide hydraulic mechanism is slid horizontally and driven laterally. The second slide mold 10 has a hole-like cavity 11 for molding the intermediate layer B.
And a through hole 12 is provided at a position where it does not interfere with the cavity 11. A runner, which will be described later, is inserted into the through hole 12 during the primary injection molding. When the mold is clamped, the intermediate mold 20 has a cavity 2 of the first mold 1,
Cavity 6 of third mold 5 and second slide mold 1
A runner 21 which is inserted into the 0 cavity 11 or the through hole 12 is provided. When the molds are similarly clamped, the runner 21 has the cavities 2 and 3 of the first mold 1.
Gates 22 and 23 opened in the cavity 6 of the die 5 and the cavity 11 of the second slide die 10, respectively.
24 are formed. A sprue 32 communicating with the runner 21 is formed on the mounting plate 30, and a locate ring 31 is mounted on the outside.

Next, a method of injection molding a three-layer structure molded product S using the above mold will be described. As shown in FIGS. 1A and 1B, the through hole 1 of the second slide mold 10 is formed.
2 is slid to a position aligned with the cavity 2 of the first die 1 and the cavity 6 of the third die 5 by, for example, a die slide hydraulic mechanism. Then, the mold is clamped by a mold clamping device (not shown). When the mold is clamped, the tip portion of the runner 21 is positioned by engaging with the rod-shaped projection 3 provided upward in the substantially central portion of the cavity 6 of the third mold 5.
Since the positioning is performed in this way, it is possible to obtain an injection-molded product with less post-processing such as deburring. The molten resin J is injected from the injection nozzle 33 by a conventionally known method (primary injection molding). Then, the resin passes from the sprue 32 of the mounting plate 30 through the runner 21 of the intermediate mold 20 to the gate 2
2 is injected into the cavity 2 of the first mold 1. At the same time, it is injected from the gate 24 to the cavity 6 of the third mold 5. Since the gate 23 is closed by the peripheral wall of the through hole 12 of the second slide mold 10, the gate 23 does not emit light. The first layer A and the third layer C are molded by this primary injection molding.

After cooling and solidification, as shown in FIG. 2A, the first die 1, the third die 5 and the mounting plate 3 are provided.
0 is appropriately separated, and the runner resin R is taken out. The second
The slide mold 10 has its cavity 11 slid to a position aligned with the cavity 2 of the first die 1 and the cavity 6 of the third die 5. Then, similarly, the mold is clamped by the mold clamping device. Also at this time, the tip of the runner 21 is positioned by engaging with the rod-shaped projection 3 provided upward in the substantial center of the cavity 6 of the third mold 5. Figure 2 (b)
As shown in FIG. 5, the molten resin J is injected from the injection nozzle 33 ′ (secondary injection molding). Then, the resin flows from the sprue 32 of the mounting plate 30 to the runner 2 of the intermediate mold 20.
It is injected from the gate 23 to the cavity 11 of the second slide mold 10 through 1. Since the gates 22 and 24 are closed by the already-molded first layer A and third layer C, respectively, molten resin is not injected from these gates 22 and 24. The intermediate layer B is molded by this secondary injection molding.

After cooling and solidification, as shown in FIG. 3, the first mold 1, the third mold 5 and the intermediate mold 20 are opened, and the ejector device 35 takes out the three-layer structure molded product S. . The same operation is repeated thereafter for injection molding.

[0015]

As described above, according to the present invention, the first mold for molding the first layer, the third mold for molding the third layer,
By using a second slide mold that is slidably provided between these molds and molds the intermediate layer, in the primary injection molding, the molten resin is closed in a state where the cavity of the second slide mold is closed. Is injected into the cavity of the first mold and the cavity of the third mold to mold the first layer and the third layer. In the secondary injection molding, the cavity of the second slide mold is changed to the first mold. Since the molten resin is slid to a position aligned with the cavity of the die and the cavity of the third die and the molten resin is injected into the cavity of the second slide die to form the intermediate layer,
With a set of dies, a third die and a second slide die,
A three-layer structure molded article can be molded. Since the number of molds is small as described above, the cost of the mold is low, the injection cycle is short, and the productivity is improved. Furthermore, according to the present invention, since the intermediate layer is injection-molded in the secondary injection molding, the first layer and the third layer are fused to the intermediate layer, which eliminates the need for a costly bonding step as in the past. Become. The invention of claim 2 is composed of a first mold, a third mold, and a second slide mold slidably provided between these molds. A first cavity for molding the first layer, a third cavity for molding the third layer on the third mold, and an intermediate cavity for molding the intermediate layer on the second slide mold. And a through hole are respectively provided, and the cavity of the second slide mold is
Since it is possible to slide between the position where the cavity of the first mold and the cavity of the third mold are aligned and the position where the through hole is aligned, in the primary injection molding, slide it to the position where the through hole is aligned, and In injection molding, a three-layer structure molded product by primary and secondary injection molding can be inexpensively molded in a short cycle simply by sliding it to a position where its cavities match.

[Brief description of drawings]

FIG. 1 is a view showing an embodiment of the present invention, in which (a) is a schematic cross-sectional view showing a mold clamped for primary injection molding, and (b) FIG. 3 is a schematic cross-sectional view showing a primary injection molding state.

FIG. 2 finishes the primary injection molding with the mold of this embodiment,
It is sectional drawing which shows the state which opened the metal mold | die and slid the 2nd slide metal mold | die, (b) is a schematic sectional drawing which shows a secondary injection molding state.

FIG. 3 is a schematic cross-sectional view showing a state where a mold of this example is opened and a three-layer structure molded product is taken out.

FIG. 4 is a diagram showing a molding method of a three-layer structure molded article by conventional adhesion, in which (a) disassembles each layer, and (b)
[Fig. 3] is a perspective view showing a state of being joined.

FIG. 5 is a diagram showing a molding method of a three-layer structure molded product by a conventional mold, in which (a) shows a state where a primary injection molded product is inserted into the mold, and (b) shows a secondary injection molded state. And (c) is a schematic cross-sectional view showing a state where the mold is opened and the three-layer structure molded article is taken out.

FIG. 6 is a view showing another molding method of a three-layer structure molded product by a conventional mold, in which (a) shows a state where a primary injection molded product is inserted into the mold, and (b) shows two. FIG. 3 is a schematic cross-sectional view showing the next injection molding state, and (C) showing the state where the mold is opened and the three-layer structure molded article is taken out.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st metal mold 2 Cavity 5 which molds a 1st layer 5 2nd metal mold 6 Cavity which molds a 3rd layer 10 2nd slide metal mold 11 Cavity which molds an intermediate | middle layer 12 Through hole A 1st layer B Intermediate layer C 3rd layer S 3 layer structure molded product

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[Procedure amendment]

[Submission date] July 15, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 is a view showing an embodiment of the present invention, in which (a) is a schematic cross-sectional view showing a mold clamped for primary injection molding, and (b) FIG. 3 is a schematic cross-sectional view showing a primary injection molding state.

It was Tsu Owa primary injection molding by Figure 2 the mold of this embodiment
It is a figure which shows a state, (a) is sectional drawing which shows the state which opened the metal mold | die and slid the 2nd slide metal mold | die, (b) is a model which shows a secondary injection molding state. FIG.

FIG. 3 is a schematic cross-sectional view showing a state where a mold of this example is opened and a three-layer structure molded product is taken out.

FIG. 4 is a diagram showing a molding method of a three-layer structure molded article by conventional adhesion, in which (a) disassembles each layer, and (b)
[Fig. 3] is a perspective view showing a state of being joined.

FIG. 5 is a diagram showing a molding method of a three-layer structure molded product by a conventional mold, in which (a) shows a state where a primary injection molded product is inserted into the mold, and (b) shows a secondary injection molded state. And (c) is a schematic cross-sectional view showing a state where the mold is opened and the three-layer structure molded article is taken out.

FIG. 6 is a view showing another molding method of a three-layer structure molded product by a conventional mold, in which (a) shows a state where a primary injection molded product is inserted into the mold, and (b) shows two. FIG. 3 is a schematic cross-sectional view showing the next injection molding state, and (C) showing the state where the mold is opened and the three-layer structure molded article is taken out.

[Description of Reference Signs] 1 First mold 2 Cavity 5 for molding first layer 5 Second mold 6 Cavity for molding third layer 10 Second slide mold 11 Cavity 12 for molding intermediate layer 12 Through hole A 1 layer B Intermediate layer C 3rd layer S Three-layer structure molded product

Claims (2)

[Claims] 1. A first mold 1 for molding a first layer A, and a third mold 1.
Primary injection molding using a third mold 5 for molding the layer C and a second slide mold 10 slidably provided between these molds 1, 5 for molding the intermediate layer B. Then, the molten resin is injected into the cavity 2 of the first die 1 and the cavity 6 of the third die 5 while the cavity 11 of the second slide die 10 is closed, and the first layer A
And the third layer C are molded, and in the secondary injection molding, the second slide mold 10 has the cavity 11 thereof, the cavity 2 of the first mold 1 and the third mold 5
Injection molding of the three-layer structure molded article S, characterized in that the intermediate layer B is molded by sliding the resin to a position aligned with the cavity 6 and injecting the molten resin into the cavity 11 of the second slide mold 10. Method. 2. A first mold 1, a third mold 5, and a second slide mold 10 slidably provided between the molds 1 and 5, wherein the first mold 1 and the third mold 5 are provided. The mold 1 has a first cavity 2 for molding the first layer A, the third mold 5 has a third cavity 6 for molding the third layer C, and the second slide mold 10 Is provided with an intermediate cavity 11 and a through hole 12 for molding the intermediate layer B, and the second slide mold 10 has the cavity 11 formed therein.
Is slidable between a position aligned with the cavity 2 of the first mold 1 and a cavity 6 of the third mold 5 and a position aligned with the through hole 12. S injection mold.