JPH054977Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to improvement of a laminated injection molding apparatus.

[Conventional technology] A skin layer with excellent surface properties is formed on the surface of a molded product, and a core layer with excellent strength properties is formed inside the skin layer, thereby satisfying different required functions on the surface and inside. Laminated injection molding is generally well known and has the great advantage of improving the surface properties of the molded product, such as weather resistance and paintability, while maintaining the required rigidity of the part. have.

However, in the above-mentioned laminated injection molding, when the core material injected after a predetermined timing pushes through the inside of the skin material that was injected first into the molding space, heat is taken away by the mold and the core material moves ahead of the skin material that was injected first into the molding space. Due to the reduced fluidity of the skin material, it is not possible to sufficiently fill the inside of the molded product with the core material, especially at the ends, and if the mounting portion of the molded product is provided at the end, the mounting There is a problem in that it is difficult to reliably provide the required strength and rigidity to the parts.

To solve this problem, for example, in Japanese Patent Application Laid-open No. 132623/1983, an extended flow path section extending outward from the end of the molded product is provided, and a skin material is applied to this extended flow path section. It has been proposed that this flow maintains the fluidity of the skin material at the ends of the molded article and prevents underfilling of the core material at the ends.

[Problems to be solved by the invention] However, in the above method, delicate changes in mold temperature are required to maintain the fluidity of the skin material at the end of the molded product and allow the skin material to flow into the extended flow path. In reality, this adjustment is quite difficult. Furthermore, as a result of providing the dummy part, the projected area of the product increases, making it necessary to make the injection molding machine larger. However, after the molding process is completed, post-processing is required to cut and remove the extended channel section provided as a dummy section, resulting in high costs.

This invention was made in view of the above problems, and aims to provide a laminated injection molding apparatus that can reliably fill the core material at the end of the molded article in a laminated injection molded product. .

[Means for solving the problem] Therefore, this invention injects a skin material and a core material into the molding space of a mold, so that the surface part and the inside are formed by the skin layer and the core layer, respectively. In a laminated injection molding apparatus for molding a molded product, a trap space is provided in a mold portion located immediately inward of the end of the molded product, and a trap space is provided in which the flow resistance of the skin material is smaller than that of the surrounding area; It is equipped with a pressure reducing device that reduces the pressure inside the space.

[Effect of the invention] According to this invention, a trap space is provided in the mold section located just inward of the end of the molded product, and the flow resistance of the skin material is smaller than that of the surrounding area, and this trap space is depressurized. This makes it easier for the skin material that has progressed through the mold space to flow into the trap space when it reaches the end.Moreover, by reducing the pressure in this trap space, the skin material flows into the trap space. The Danskin material becomes more difficult to flow toward the edges. As a result, the amount of skin material directed toward the ends is reduced, and the ends of the molded article can be reliably filled with the core material.

[Example] Hereinafter, an example of this invention will be described in detail based on the accompanying drawings.

As shown in FIG. 4, the laminated injection molding apparatus 1 (hereinafter simply referred to as the apparatus) according to the present embodiment includes a fixed mold 2 attached to a fixed mold platen 4, and one end of which is fixed to the fixed mold platen 4. a plurality of tie rods 6 arranged parallel to each other; a movable die platen 5 through which the plurality of tie rods 6 are inserted and slidably provided on the tie rods 6, . . . , 6; It is equipped with a movable mold 3 attached to a mold board 5, and the movable mold 3 can move forward and backward relative to the fixed mold 2 by driving the movable mold board 5 with a drive device (not shown). It is becoming possible to do this. Further, on the central side of the fixed mold platen 4, there is a nozzle unit 7 for injecting the skin material and the core material into the forming space formed by the fixed mold 2 and the movable mold 3.
is arranged so that it can move forward and backward.

In this example, the skin material is a non-filler resin material with excellent surface properties, and the core material is a filler-containing resin material with high strength and rigidity, such as reinforced glass fiber added. was used.

As shown in detail in FIG. 5, the nozzle unit 7 includes a first cylinder 16 for injecting the skin material, a second cylinder 17 for injecting the core material, and an injector for injecting the skin material and the core material. A substantially cylindrical sleeve member 24 that accommodates the shaft-off pin 25 is provided inside the nozzle main body 23 so as to be slidable in the axial direction (left-right direction in the figure). It is being

The first cylinder 16 and the second cylinder 17 are provided with a first spindle 18 and a second spindle 19 that open and close the insides of the cylinders 16 and 17 with respect to the skin material passage 21 and the core material passage 22, respectively.
are provided respectively, and the skin material passage 2
1 is the nozzle main body 23 and the sleeve member 24;
The core material passage 22 communicates with a second space 24b formed between the sleeve member 24 and the shaft-off pin 25.

Further, a first nozzle hole 23a and a second nozzle hole 24a are provided at the tips of the nozzle main body 23 and the sleeve member 24, respectively. While the second nozzle hole is opened and closed at its tip, the second nozzle hole is also opened and closed at its tip as the shutter-off pin 25 also moves from side to side.

The operation of the device 1 having the above configuration will be explained below.

First, the movable mold 3 is driven toward the fixed mold 2 and the mold is clamped. Next, the nozzle unit 7 is moved to the left and positioned at the injection position (see FIG. 5) where its tip end is immersed in the cavity 4a of the fixed mold platen 4.

At this time, both the first nozzle hole 23 and the second nozzle hole 24a are closed, and the first spindle 18 and the second spindle 19 connect the first cylinder 16 and the second cylinder 17 to the skin material passage, respectively. 21 and the core material passage 22 .

Next, the spindle 18 of the first cylinder 16 moves to the right, and the skin material in the first cylinder 16 fills the skin material passage 21 and the first space 23b.
Further, the spindle 19 of the second cylinder 17 moves to the right, and the core material in the second cylinder 17 is filled into the core material passage 22 and the second space 24b. Note that this filling of the core material may be performed immediately before the core material is injected.

Then, by moving the sleeve member 24 to the right, the first nozzle hole 23a is opened, and the skin material in the first space 23b is transferred into the molding space 10 through the cavity 4a of the fixed mold platen 4. is injected into the Then, when the injection amount of skin material reaches a predetermined amount,
The sleeve member 24 is moved to the left and the first nozzle 23a
is closed.

Next, when a predetermined period of time has elapsed after the injection of the skin material is completed, the shutter-off pin 25 is moved to the right to open the second nozzle hole 24a, and the core material stored in the second space 24b is released into the molding space. 10
It is ejected inside. When the amount of core material injected reaches a predetermined amount, the above-mentioned shutter-off pin 25 is moved to the left to close the second nozzle 24b.

After completing the injection of the skin material as described above,
By injecting the core material after a predetermined timing delay, the core material pushes inside the skin material in the molding space 10, and as a result, a skin layer made of the skin material is formed on the surface of the molded product, while It is possible to obtain a laminated injection molded product in which a core layer made of a core material is formed inside.

By the way, in this embodiment, as shown in FIG. 2, the end Wa of the molded product W, which is provided downward from the main body Wh, has a mounting hole for attaching the molded product W to other parts. Wb is provided. Then, in order to reliably fill the core material around the end Wa of the molded product, especially around the mounting hole Wb, the end Wa of the fixed mold 2 is placed, for example, at a position directly inward of the part where the end Wa is to be molded. A trap space for trapping the skin material is provided.

This trap space will be explained below.
FIG. 1 is an enlarged cross-sectional view of the mold part for molding the end Wa of the molded product W. are the main body part 10h and the end part 10 of the molding space 10.
A space 10c (trap space) having a triangular cross section is formed. Therefore, the portion of the molding space 10 from the main body 10h to the end 10a is the trap space 10c.
As shown in FIG. 3a, the skin material Sw advancing through the molding space 10 passes through this trap space 10c when reaching the end portion 10a from the main body portion 10h. It is becoming easier to flow inside. The trap space 10c is located directly inside a pin portion 2b that protrudes from the fixed mold 2 toward the movable mold 3, for example, in order to form a mounting hole Wb for the molded product W. 2
It has a width dimension larger than the outer diameter dimension of b.

Furthermore, a passage portion 2f that opens into the space portion 10c and also opens on the side surface of the fixed mold 2 is provided in a portion of the fixed mold 2 corresponding to the space portion 10c, and the passage portion 2f has a fourth passage portion 2f. As shown in the figure, the suction duct 11 attached to the side part of the fixed mold 2
via surge tank 12 and vacuum pump 13
It is connected to the. The passage section 2f is filled with a porous material 31 that allows air to easily pass therethrough, and by driving the upper air vacuum pump 13, air in the space section 10c is sucked through the porous material 31. The pressure inside the space 10c can be reduced.

As shown in FIG. 3b, the skin material Sw that has flowed into the trap space 10c is sucked toward the passage portion 2f by reducing the pressure in the trap space 10c, and becomes difficult to flow toward the end portion 10a. As a result, as shown in FIG. 3c, the amount of skin material Sw flowing into the end portion 10a is reduced, and the core material CW is transferred to the end portion 10a, particularly in the attachment hole 1 of the molded product W.
It is possible to reliably fill the area around the pin portion 2b for forming the 0b.

As described above, according to this embodiment, a trap space 10c is provided in the mold section located just inward of the end Wa of the molded product W, into which the skin material Sw flows more easily than the surrounding area, and this trap space Since the pressure in the mold space 10c is reduced, the skin material Sw that has progressed within the mold space 10 easily flows into the trap space 10c when reaching the end portion 10a.
Furthermore, by reducing the pressure in the trap space 10c, the skin material Sw that has flowed into the trap space 10c becomes difficult to flow toward the end portion 10a. As a result, the amount of skin material Sw directed toward the end 10a is reduced, and the end Wa of the molded article W can be reliably filled with the core material Cw.

In the above embodiment, the cross-sectional shape of the trap space 10c is a right triangle (see FIG. 2), but this can be changed to other shapes, for example, as shown in FIG. By forming a shape in which the hypotenuses are connected by a curve that descends in a wavy manner from the main body part Wh' of the molded product W' toward the end part Wa', the skin material that has flowed into the trap space is made more difficult to flow toward the end part. be able to.

[Brief explanation of the drawing]

The drawings are all for explaining the embodiment of the present invention, and FIG. 1 is an enlarged sectional view of the mold part for forming the end of the molded product, FIG. 2 is a perspective view of the end of the molded product, and FIG. 3a, 3b, and 3c are a series of sectional explanatory views of the ends of the mold to explain the inflow state of the skin material and the core material, and FIG. 4 is a schematic configuration diagram showing the overall configuration of the laminated injection molding apparatus. Fig. 5 is a cross-sectional view of the main part of the nozzle unit of the laminated injection molding apparatus, and Fig.
The figure is a perspective view of the end of a molded product according to another embodiment of the present invention. 1... Laminated injection molding device, 2... Fixed type, 2f
... Passage part, 3 ... Movable mold, 10 ... Molding space,
10c... Trap space, 11... Suction duct, 12... Surge tank, 13... Vacuum pump, 31... Porous material, Cw... Core material, Sw
...Skin material, W...molded product, Wa...molded product end.

Claims (1)

[Claims for Utility Model Registration] Laminated injection molding in which a skin material and a core material are injected into the molding space of a mold to form a molded product whose surface and interior are each formed by a skin layer and a core layer. In the apparatus, a trap space is provided in the mold section located directly inward of the end of the molded product, and a trap space is provided where the flow resistance of the skin material is smaller than that of the surrounding area, and a pressure reducing device is provided to reduce the pressure in the trap space. A laminated injection molding device characterized by: