JPH07100890A - Method and device for manufacture of resin injection molded product - Google Patents

Abstract

PURPOSE:To fill molten resin in a plurality of branches of different volume without excess or deficiency by improving the flow balance of molten resin in a cavity. CONSTITUTION:Seven bar-shaped heaters 27 are implanted as heating means in outer split molds 3 and 4. Of all the heaters 27, six of them are implanted on a section encircling a branch 5b of large volume cavity 5 on the right side, while the rest one is implanted on a section encircling a branch 5a of small volume cavity on the left side. Power is applied independently for control to the six heaters 27 on the right side and one heater 27 on the left side respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin injection molded article manufacturing method and apparatus, and more particularly to a technique for improving the flow balance of molten resin in a cavity.

[0002]

2. Description of the Related Art In recent years, a resin injection molding apparatus has been widely used for mass production of lightweight and high-strength members. FIG. 5 shows a main part of an FRP injection molding device for molding a tubular body. In this device, cylindrical mold slide cores 1 and 2 for separating a molding die into right and left, and FIG. (A cross-sectional view taken along the line AA) of FIG. A gate 7 and a runner 8 provided when the molten resin 6 is injected into the cavity 5 are provided on the divided surfaces of the outer mold halves 3 and 4.
Are formed on the upper part thereof, and further, the split outer mold 3 is formed with a sprue 9 communicating with the runner 8.

At the time of manufacture, a molten resin 6 is pressure-fed from an injection device (not shown), and is injected from the gate 7 into the cavity 5 through the sprue 9 and the runner 8. The injected molten resin 6 flows toward both axial ends of the cavity 5 as shown in FIG. 5, and along the outer periphery of the slide core 1 near the gate 7 as shown in FIG. And wrap around from the left and right. Thereafter, the molten resin 6 filled in the cavity 5 is cured by cooling or heat treatment to form a cylindrical body, and the slide cores 1 and 2 and the outer mold halves 3 and 4 are moved open to form the cylindrical body 10. Take it out. Finally, using a cutting tool, etc., as shown in FIG.
The portions of the gate 7 and the runner 8 are removed from the tubular body 10.

[0004]

The tubular body 10 manufactured by the above-mentioned method has the following problems. As is well known, in the FRP molded product, the strength is ensured by the contained glass fiber having high tensile strength.
That is, even if a large tensile stress or bending stress is applied to a certain portion, the glass fibers that are overlapped with each other resist these stresses and are less likely to break. However, as described above, when the tubular body 10 is manufactured, the molten resin 6 flows into and merges from the left and right in the vicinity of the gate 7, and therefore, as shown in FIG. 7, the merged position (opposite the gate 7 in the illustrated example). A weld (bonding boundary surface between the molten resins 6) 11 is formed in the region. In the weld 11, since the glass fibers do not overlap each other as a matter of course, the strength of the finished product is significantly reduced. For example, in the case of an FRP molded product containing 40% glass fiber, it has been confirmed that the strength of the weld 11 is 40 to 50% lower than that of other parts. Therefore, when the weld 11 is located at a site where pressure resistance is required in a component member or the like of the faucet device, it cannot withstand high water pressure.

Therefore, conventionally, there has been adopted a method for solving this problem by arranging the portion where the weld 11 is generated, that is, the gate 7 at a portion where water pressure is not applied. But,
According to this method, as shown in FIG. 8, when the portion (indicated by 18a in the drawing) for which pressure resistance is required is in the central portion of the cavity 5, the gate 7 must be offset toward the end portion in the axial direction. Therefore, the flow balance of the molten resin becomes a problem. That is, if the cavity 5 is divided into the left side branch 5a and the right side branch 5b with the gate 7 as a boundary, the time required to fill the injected molten resin 6 becomes longer in the left side branch 5a having a large volume. , Small right branch 5
On the contrary, it becomes shorter in b. As a result, the molten resin 6 is solidified in the left branch 5a with insufficient filling, and the molten resin enters the mating surfaces of the outer split molds 3 and 4 in the right branch 5b to form a burr 12. I was afraid. If such a molding defect occurs, it will not be a product or burr 12
There was a problem that it took a lot of time to remove the above.

Therefore, the present invention solves the problems of the above-mentioned prior art, improves the flow balance of the molten resin in the cavity, and enables the plurality of branches having different volumes to be filled with the molten resin in just proportion. An object of the present invention is to provide a method and an apparatus for manufacturing an FRP injection molded product.

[0007]

In the method for producing a resin injection-molded article according to the present invention, which achieves the above object, a molten resin is injected from a gate into a cavity of a molding die and the volume of the cavity is varied. A method of manufacturing a resin injection-molded article by filling a plurality of branches, wherein a mold temperature of a part surrounding a larger volume of the branches is a mold temperature of a part surrounding a smaller volume. After making it higher,
It is characterized in that the molten resin is injected from the gate.

Further, an apparatus for producing a resin injection-molded article according to the present invention, which carries out the above method, includes a molding die having a gate for injection of molten resin, and a molding die formed in the molding die.
A cavity formed by a plurality of branches having different volumes from the gate and a portion surrounding a larger volume of the plurality of branches in the molding die are heated to a higher temperature than a portion surrounding a smaller volume. And a heating means.

[0009]

In the present invention, the inflowing molten resin is quickly filled in the large volume branch of the cavity having a high mold temperature, while the molten resin filling speed becomes low in the small volume branch of the mold temperature being low. Uniform molding is possible.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a molding die for an inner cylinder of a mixed faucet will be described below with reference to the accompanying drawings. As shown in FIG. 1, the casing 13 of the mixed faucet has a hot water supply pipe 14, a water supply pipe 15, and a spout 16 on the outer surface.
Is formed of an outer cylinder 17 made of a brass pipe to which is connected, and an inner cylinder 18 of a resin molded product inserted and fitted into the outer cylinder 17. As shown in FIG. 2, the outer diameter of the inner cylinder 18 is the outer cylinder 17
Is smaller than the inner diameter of the inner cylinder 18
Partitioned by an annular or linear partition wall 19 projecting from the outer surface of the water, water and water passages 20 and 21 are formed. A packing groove 22 that opens toward the inner surface of the outer cylinder 17 is continuously formed in the partition wall 19, and a packing 23 made of synthetic rubber is fitted into the packing groove 22 so that a space between the water passages 20, 21, etc. Sealing is done. Also, the inner cylinder 1
A temperature adjusting unit 25 and a flow rate adjusting unit 26 are attached to the hollow portion 24 of the right and left 8 from the left and right.

The inner cylinder 18 is relatively complicated in shape, but is also required to have pressure resistance in consideration of mass productivity and water hammer.
Therefore, in the present embodiment, an injection molded article of FRTP (fiber reinforced thermoplastic) in which fibers such as glass and carbon are mixed in resin is used. Further, in this embodiment, since the high pressure water flows from the center of the inner cylinder 18 to the right side portion, this right side portion is a pressure resistant portion (indicated by 18a in the figure).
Has become.

A molding die for molding the inner cylinder 18 also has cylindrical slide cores 1 and 2 which are separated into right and left in FIG. 3 and B in FIG. (-B cross-sectional view), it is formed of separate outer dies 3 and 4 which are separated into left and right. Further, a gate 7 and a runner 8 which are provided when the molten resin 6 is injected into the cavity 5 are formed in the lower portion of the split surfaces of the split external dies 3 and 4, and
A sprue 9 that communicates with the runner 8 is formed there. The gate 7 is arranged on the left side of the cavity 5 in order to prevent the occurrence of welds in the breakdown voltage portion. Therefore, when the cavity 5 is divided into the left branch 5a and the right branch 5b with the gate 7 as a boundary, the volume of the right branch 5b is increased due to the difference in wall thickness.
It is several times larger than the volume of a.

As shown in FIGS. 3 and 4, in the split outer molds 3 and 4 of this embodiment, a total of seven rod-shaped heaters 2 are used as heating means.
7 is buried. Of these heaters 27, six are embedded in the portion surrounding the right branch 5b of the cavity 5, and one is embedded in the portion surrounding the left branch 5a. The six heaters 27 on the right side and the one heater 27 on the left side are independently energized and controlled by a controller (not shown). In the figure, 28 is a heat insulating plate embedded in the outer mold halves 3 and 4.

In the present embodiment, prior to the manufacture of the inner cylinder 18, the six heaters 27 on the right side and the heaters 27 on the left side are appropriately energized, and the branch 5b on the right side of the cavity 5 in the outer mold halves 3 and 4 is separated. Branch the temperature on the left side to the temperature of the surrounding part 5a
Set higher than the temperature of the surrounding area. Then, the injection device (not shown) is driven to inject the molten resin 6 into the cavity 5. Then, in the branch 5b on the right side of the cavity 5, the temperature of the molten resin 6 is kept high and the filling is performed relatively quickly. Therefore, the molten resin 6 does not solidify in the state of insufficient filling. On the other hand, in the branch 5a on the left side of the cavity 5, the temperature of the molten resin 6 becomes low and the filling speed becomes relatively low. Therefore, no burrs are generated due to the molten resin entering the mating surfaces of the outer mold halves 3 and 4.

In this embodiment, since such a manufacturing method is adopted, the manufactured inner cylinder is free from insufficient filling, burrs and the like, and high productivity can be secured.

Although the above-mentioned embodiment relates to the manufacture of the inner cylinder used for the mixed faucet, it may be one that manufactures parts other than the faucet, and the shape thereof is not limited to a cylinder, but a rectangular cylinder. It may have a shape or the like. Further, the present invention may be applied to an apparatus for injection-molding a resin other than FRP, or may be applied to an apparatus having three or more cavities. Further, the heating means may be provided only in the branch having the larger volume, or a heating means other than the rod-shaped heater may be used.

[0017]

As is apparent from the above description, according to the present invention, in a resin injection-molded product having a plurality of branches having different volumes, it is possible to prevent insufficient filling, burrs, etc. It greatly improves the sex.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing a double-tube type faucet casing.

FIG. 2 is an enlarged sectional view of a main part of the same faucet casing.

FIG. 3 is a vertical sectional view showing an embodiment of an FRP injection molding device according to the present invention.

4 is a sectional view taken along line BB in FIG.

FIG. 5 is a vertical sectional view showing an example of a conventional FRP injection molding apparatus.

6 is a cross-sectional view taken along the line AA in FIG.

FIG. 7 is a sectional view showing an inner cylinder manufactured by a conventional FRP injection molding apparatus.

FIG. 8 is a longitudinal sectional view showing an example of a conventional FRP injection molding device.

[Explanation of symbols]

 1, 2 Slide core 3, 4 Split outer mold 5 Cavities 5a, 5b Branch 6 Molten resin 7 Gate 27 Heater 28 Heat insulating plate

Claims (2)

[Claims] 1. A method for producing a resin injection-molded article by injecting a molten resin into a cavity of a molding die from a gate and filling the plurality of branches having different cavities with different volumes. Among them, the molten resin is injected from the gate after the mold temperature of the part surrounding the larger volume is made higher than the mold temperature of the part surrounding the smaller volume. Molded article manufacturing method. 2. A molding die having a gate for injection of molten resin, a cavity formed in the molding die, the cavity having a plurality of branches having different volumes from the gate, and the molding die. An apparatus for manufacturing a resin injection-molded article, comprising: a heating unit that heats a portion of the plurality of branches that surrounds a larger volume to a higher temperature than a portion that surrounds a smaller volume.