JPH1095034A - Molding press molding method and mold for molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid molding defects such as short shot and the like by a method wherein inner pressure of a cavity in molding is controlled to be almost uniform even when variation of a feed amount of semi-molten resin to an inside of a cavity, or variation of resin distribution occurs. SOLUTION: By arranging buffer devices such as cushion rubber 36, spring, hydraulic damper, etc., between a mounting plate 32 and cavities 33a-33c in a molding press molding top force 30, variation of a resin amount to respective cavities A, B, C is absorbed by the buffer devices in the case of a multi-cavity mold, and variation of resin distribution in the cavity A is absorbed by the buffer device in the case of the single cavity A. An inner pressure of the cavity is controlled constant with a low cost structure to raise precision in molding.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold press molding method suitable for molding interior parts for automobiles and a mold for molding the same.

[0002]

2. Description of the Related Art For example, there is a mold press molding method as a method of molding interior parts for automobiles. In this mold press molding method, a semi-molten resin material is distributed and supplied into upper and lower molds for mold press molding. By using the upper and lower mold dies, it is possible to obtain an interior part with less material loss and excellent moldability.

In order to carry out this mold press molding method, as shown in FIG. 9, a resin is placed between upper and lower mold press molds 1 and 2 which can be engaged and pressed and have a desired cavity shape. The resin material is supplied through an injection molding machine 3 connected to the lower mold 1 for molding a molded body.

That is, the semi-molten resin is supplied from the nozzle 3a of the injection molding machine 3 to the hot runner 4, and distributed to the mold surface of the lower mold 1 through a plurality of gates 5 branched from the hot runner 4. Supplied.

[0005] In recent years, when molding mass-produced products such as interior parts for automobiles, in consideration of molding efficiency, multi-cavity mold press molding for obtaining a plurality of molded products in one press step is performed. Many.

For example, as shown in FIG. 10, the case of taking two pieces will be described. As an example, a pair of lower dies 1 are mounted on a receiving plate symmetrically on the left and right, and It is set to be symmetric.

Then, semi-molten resin material is injected and filled into the cavities a and b formed by the upper and lower molds 1 and 2 from the injection molding machine 3 through the hot runner 4 and the gate 5,
A molded product conforming to the shapes of the cavities a and b is molded.

However, in the multi-cavity mold press molding method, although the cavity capacities a and b are the same, they are injected from the injection molding machine 3 into the cavities a and b through the hot runner 4 and the gate 5. The amount of semi-solid resin material is not always the same.

This means that when a temperature difference occurs in the hot runner 4 that supplies the resin to each of the cavities a and b, the fluidity of the semi-molten resin differs between the gates 5.
Alternatively, a change in the flow resistance of the semi-molten resin due to a residual unmelted resin or a spool remaining or a foreign substance mixed in the resin causes a difference in a supply amount of the resin material to each of the cavities a and b. I have.

As described above, if the amounts of the resin injected and filled in the cavities a and b are not the same, one side is overfilled and burrs are likely to occur, and the other side is defective in molding such as short shot due to poor filling. .

As a countermeasure against this, the applicant has previously filed Japanese Patent Application No. 5-1.
No. 34850 has been filed. As shown in FIG. 11, the content of overfilling of the resin material is caused to overflow by the cushion valve 6 provided in the lower mold 2 so that the internal pressure of each of the cavities a and b is made constant.

[0012]

However, in the countermeasure shown in FIG. 11, the mold processing cost is high and the cushion valve 6 must be set at an appropriate position so as not to interfere with the gate 5 and the like. There was a disadvantage that the degree of freedom in designing the mold was restricted.

When the internal pressure of the cavities a and b changes due to a change in the grade of the resin, it is necessary to change the setting, and the management is troublesome, and the resin flows while forming the skin layer. At the same time, it has been pointed out that a sufficient internal pressure of the cavity cannot be achieved due to the influence of the above.

The present invention has been made in view of such circumstances, and can be applied to a single mold structure. In particular, the present invention relates to a mold press molding method and a molding die suitable for multi-cavity molding. Therefore, a molding press molding method and a molding die for molding can be surely prevented in which molding defects such as burrs and short shots can be prevented, mold processing costs can be reduced, and the degree of freedom in molding the mold is not restricted. It is intended to provide.

[0015]

According to the present invention, a semi-molten resin is injected and filled by an injection molding machine into a cavity formed by a plurality of cavity molds and a corresponding core mold. In a multi-cavity mold press molding method for mold press molding a plurality of molded products, a buffer device is provided between the plurality of cavity dies and a mounting plate, and the buffer device is supplied to the cavity by a buffering action of the buffer device. It is characterized by absorbing variations in the amount of resin and controlling the internal pressure of the cavity almost uniformly.

Further, according to the method of the present invention, a mold formed by injection-filling a semi-molten resin from an injection molding machine into a cavity formed by a single cavity mold and a core mold, and press-molding a single molded product. In the molding method, a buffer device is provided between the cavity mold and a mounting plate, and the buffering action of the buffer device absorbs a variation in resin distribution in the cavity and controls the internal pressure of the cavity substantially uniformly. Features.

The mold press molding die used in the present invention distributes and supplies a resin material into the cavity through a mold press molding upper and lower mold for forming a desired cavity space and a gate formed in the lower mold. And a buffer device interposed between the mounting plate and the cavity mold in the upper mold press molding die.

Here, the upper mold for mold press molding has a single or a plurality of cavity dies mounted on a mounting plate mounted on a lower surface of a press machine capable of moving up and down by a predetermined stroke via mounting hardware. I have.

In particular, a shock absorber is interposed between the mounting plate and the cavity mold. The shock absorber may be a cushion rubber such as synthetic rubber or natural rubber, a spring such as a spring, or a spring-like member. , Hydraulic dampers and the like are applicable.

On the other hand, in the lower mold for mold press molding, a core mold is mounted on a receiving plate corresponding to the cavity mold, and a gate for supplying a semi-molten resin is formed in the core mold. Accordingly, the semi-molten resin is distributed and supplied from the injection molding machine and the hot runner connected to the lower mold to the mold surface of the lower mold through the gate.

As is apparent from the above configuration, when the method of the present invention is applied to a multi-cavity mold press molding method, a plurality of cavity molds are mounted on a mounting plate via cushioning devices such as cushion rubbers and springs. Has been
If the supply amount of the semi-molten resin material supplied to a plurality of cavities varies, based on the minimum supply amount of cavities, in the cavities that are overfilled,
Since a cushioning device such as a cushion rubber or a spring bends and a predetermined press pressure is applied to the cavity with the smallest supply amount, the internal pressure of each cavity is controlled substantially uniformly.

Further, when the present invention is applied to a molding method using a single cavity mold, even if the resin distribution in the cavity varies, the upper mold is slightly inclined by a cushioning device such as a cushion rubber or a spring. Variations in the internal pressure distribution in the cavity can be absorbed.

Further, when a hydraulic damper is used as a shock absorber, oil in a hydraulic damper provided in an overfilled cavity mold flows into another hydraulic damper, and an appropriate press pressure is reduced by this hydraulic damper. In addition to the filling cavity mold, a substantially uniform cavity pressure can be secured in all the cavities.

[0024]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a side view showing the entire structure of a mold press forming apparatus used in the method of the present invention, FIG. 2 is a sectional view showing the structure of a mold press forming die according to the present invention, and FIGS. 5 to 8 are cross-sectional views showing another embodiment of the upper die in the mold press molding apparatus according to the present invention.

First, referring to FIG. 1 and FIG. 2, the overall configuration of a mold press molding apparatus applied to the case of multi-cavity production will be described.

The mold press molding apparatus comprises a mold press molding die 10 and an injection molding machine 20 connected thereto. The mold press molding die 10 includes an upper mold press molding die 30 and a lower mold press molding die 30. And a mold 40.

Then, the upper mold 30 for mold press molding is used.
A plurality of cavity dies 33a, 33b, and 33c are mounted on a mounting plate 32 mounted on the lower surface of a press machine 31 via cushion rubbers 34, respectively.

On the other hand, the lower mold 40 for mold press molding is
Core molds 42a, 42b, 42c are mounted on a receiving plate 41 corresponding to the cavity molds 33a, 33b, 33c, and a semi-molten resin supplied from a nozzle of the injection molding machine 20 is passed through a hot runner 21 to form a core mold. The structure is such that the material is distributed and supplied to predetermined locations on the mold surface of each core mold 42 through a gate 43 formed in the mold 42.

A feature of the mold press molding apparatus according to the present invention is that a cushioning device such as a cushion rubber 34 is interposed between the mounting plate 32 and the cavity mold 33 in the upper mold 30.

More specifically, referring to FIG. 2, the support plate 3 connected to the cylinder 31a of the press machine 31 will be described.
1b, the mounting plate 32 is supported on the lower surface.
The mounting plate 32 is fixed to the lower surface of the support plate 31b of the press machine 31 by inserting the embedded bolt 35 of 1b into the mounting hole 32a of the mounting plate 32 and tightening the nut 35a from the tip side.

On the other hand, on the lower surface of the mounting plate 32, the respective cavity dies 33a, 33
b and 33c are fixed, but this fixing structure is performed via a mounting bracket 36.

That is, as shown in an enlarged manner in FIG. 2, a stepped hole 32b is formed in the mounting plate 32 so that a large-diameter head portion 36a of the mounting bracket 36 can be accommodated. A threaded portion 36b having a thread groove formed therein is formed at the tip of the cavity die 33. Each cavity mold 33 is fixed to the mounting plate 32 by screwing a plurality of mounting brackets 36.

When excessive press pressure is applied to the cavity mold 33, the cushion rubber 34 bends, and the cushion rubber 34 is bent between the upper surface of the head portion 36a of the mounting bracket 36 and the lower surface of the support plate 31b of the press machine 31 in FIG. The cushion rubber 34 can be bent by the dimension shown.

Next, the molding process of the above-mentioned mold press molding apparatus will be described with reference to FIGS.

First, as shown in FIG. 3, the lift cylinder 31a is movable, and the cavity dies 33a, 33b, 33c fixed via the press machine 31 and the mounting plate 32.
Is lowered by a predetermined stroke, and when the clearance between the cavity mold 33 and the core mold 42 reaches a clearance of 10 to 50 mm, the injection molding machine 20, the hot runner 21, and the gate 43 are moved.
a, 43b, and 43c, each core type 42a, 42b,
The semi-solid resins M ₁ , M ₂ , and M ₃ are respectively distributed and supplied to the upper surface of 42c.

That is, semi-solid resins M ₁ , M ₂ , and M ₃ are supplied into the cavities A, B, and C, respectively.

At this time, the temperature difference of the hot runner 21 and the fluidity of the semi-molten resin depend on the respective gates 43a, 43b,
It is unavoidable that the supply amounts M ₁ , M ₂ , and M ₃ of the semi-molten resin material slightly vary due to the difference depending on 43c, the residual unmelted resin or the spool remaining, or the inclusion of foreign matter in the resin. .

For example, the amount of resin supplied to the cavities A, B, C is M ₁ : 102%, M ₂ : 96.
%, M ₃ : 102%, a molding failure such as a short shot is expected to occur in the cavity B due to insufficient supply of the resin in the cavity B.

However, if the mold press molding apparatus according to the present invention is used, as shown in FIG. 4, if the upper die 30 is lowered to the bottom dead center and the mold press molding is performed, the amount of resin is overfilled. For the cavities A and C, the cushion rubber 3 installed in the cavity molds 33a and 33c is used.
By bending the 4a and 34c, an appropriate press pressure is applied from the cavity mold 33b even in the cavity B where the resin supply amount is slightly small, and molding defects such as short shots do not occur in the cavity B. Become.

As the cushion rubber 34, silicone rubber or urethane rubber having a spring constant of about 0.1 (mm) / 80 (kg / cm ² ) is used.

Therefore, even if the supply amounts M ₁ , M ₂ , and M ₃ of the semi-solid resin supplied to the cavities A, B, and C vary, the cushion rubber 34 absorbs the dispersion, and the cavity mold 34 absorbs the dispersion. 33, an appropriate press pressure is obtained, and the internal pressures of the cavities A, B, C can be controlled almost uniformly.

The mold press molding apparatus according to the present invention has a simple structure in which the cushion rubber 34 is interposed between the mounting plate 32 and the cavity mold 33, so that the mold processing cost can be reduced, and Unlike a conventional mold structure in which a cushion valve is set in a lower mold, there are no restrictions on molding.

Next, FIG. 5 shows an embodiment in which a coil spring 37 is used in place of the cushion rubber 34 in the mold press molding apparatus according to the present invention. mm) / 80
(kg / cm ² ).

It is also possible to use a hydraulic damper 50 as one form of the shock absorber. As shown in FIG. 6, in this embodiment, two cavity dies 33a and 33b are set on the mounting plate 32. The mold structure will be described.

That is, a plurality of cylinders 51 are fixed to the lower surface of the mounting plate 32, and the tip of a piston rod 53 of a piston 52 that moves up and down in the cylinder 51 is fixed to the cavity molds 33 and 33b. The oil in the cylinder chamber 54 of the cylinder 51
a, 54b, 54c, 54d)
5 are arranged so as to connect the cylinder chambers 54.

Therefore, when the cylinders 51a and 51b are installed in the cavity mold 33a on one side and the cylinders 51c and 51d are installed in the cavity mold 33b on the other side, the amount of resin supplied to the cavities A and B is In case of overfilling, cavity B
Since the internal pressure in the inside becomes higher than the internal pressure in the cavity A,
Due to the repulsive force of the cavity mold 33b, the cavity mold 33b
Pistons 52 of cylinders 51c and 51d installed in
c and 52d rise, the oil in the cylinder chambers 54c and 54d flows into the respective cylinder chambers 54a and 54d of the other cylinders 51a and 51b through the pipe 55, and the pistons 52a and 52b of the cylinders 51a and 51b into which the oil flows.
Lowers, and the hydraulic pressure causes the cavity mold 33a to move downward.
And the internal pressure of the cavity A is controlled to be substantially equal to that of the cavity B.

As described above, even if the amount of resin varies in the cavities A and B due to the buffering action of the hydraulic damper 50, the internal pressures of the cavities A and B can be controlled to be substantially equal, and short shots and the like can be controlled. Molding defects can be prevented beforehand.

The above description has been given of the mold press molding method for forming a large number of molded articles and the molding apparatus used therein. However, the method of the present invention can be applied to a case where a single cavity mold 33 is provided on the mounting plate 32 such as a large molded article. Can be applied effectively.

That is, as shown in FIG. 7, the upper die 30 has a configuration in which a mounting plate 32 is fixed to a press machine 31, and cushion rubbers 34d and 34 are attached to the mounting plate 32.
A single cavity mold 33 is attached via e, and as a configuration of the lower mold 40, a single core mold 42 is also provided so as to correspond to the cavity mold 33.

As shown in FIG. 8, when a uniform resin distribution cannot be obtained over the entire area of the cavity A during mold press molding, for example, a part of the area A ₁ of the cavity A is replaced with another area A _{1. When} a larger amount of resin is supplied than in the case of ₂ , the cushion rubber 34d on the overfilling side bends more than the other 34e, and the cavity mold 33 is slightly inclined, so that a uniform internal pressure in the cavity A is ensured. And molding defects such as short shots do not occur.

[0052]

As described above, the present invention has the following special effects and advantages.

(1) When the method of the present invention is applied to a multi-cavity mold press molding method, when the amount of resin supplied to a plurality of cavities fluctuates, the cushioning device installed on the mounting plate and the cavity mold is used. By the action, the variation in the amount of resin can be absorbed, and the resin pressure in each cavity can be controlled almost uniformly. Therefore, even if there is a filling failure, it is possible to prevent a molding failure such as a short shot. Thus, the yield of the product is improved, and the productivity can be greatly increased.

(2) If the method of the present invention is applied to a single molded product, even if the resin distribution in the cavity varies, the cushioning device installed between the mounting plate and the cavity mold can be used. Variations in resin distribution can be effectively absorbed, molding defects such as short shots can be prevented beforehand, and a large molded article having a complicated shape can be molded with high accuracy.

(3) In the method of the present invention, a buffer device is provided between the mounting plate and the cavity mold, and when a plurality of cavities are provided, the amount of resin in each cavity varies. Since the variation in the resin distribution at the step is absorbed by the shock absorber, the temperature of the molding die and the molding conditions can be set relatively roughly, so that the process management can be easily performed. .

(4) The mold press molding die according to the present invention has a simple structure in which a cushioning device such as a cushion rubber, a spring, or a hydraulic damper is interposed between the mounting plate and the cavity mold in the upper mold structure. Therefore, the present invention can be implemented at low cost, and has an effect that there is no restriction on the degree of freedom of molding of the mold as compared with the conventional structure in which the cushion valve is disposed in the lower mold.

[Brief description of the drawings]

FIG. 1 is a side view showing the overall configuration of a mold press molding apparatus used in the method of the present invention.

FIG. 2 is a sectional view taken along line II-II in FIG.

FIG. 3 is a sectional view showing a filling step of a semi-molten resin in the method of the present invention.

FIG. 4 is a sectional view showing a mold press molding step in the method of the present invention.

FIG. 5 is a cross-sectional view showing another embodiment of the shock absorber in the mold press forming apparatus used in the present invention.

FIG. 6 is a sectional view showing still another embodiment of the shock absorber in the mold press molding apparatus used in the present invention.

FIG. 7 is a side view showing another embodiment of the mold press molding apparatus used in the method of the present invention.

FIG. 8 is a sectional view showing a mold press molding step using the molding apparatus shown in FIG. 7;

FIG. 9 is a side view showing a conventional mold press molding apparatus.

FIG. 10 is a sectional view taken along line XX in FIG. 9;

FIG. 11 is a sectional view showing a conventional mold press molding step.

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 Mold press molding die 20 Injection molding machine 30 Mold press molding upper die 31 Press machine 32 Mounting plate 33 Cavity die 34 Cushion rubber 36 Mounting bracket 40 Mold press molding lower die 42 Core die 43 Gate 37 Coil spring 50 Hydraulic pressure Damper 51 Cylinder 52 Piston 54 Cylinder chamber 55 Piping

Claims (6)

[Claims] A plurality of cavity molds (33a, 33b,
33c) and the corresponding core type (42a, 42b, 4)
Cavity (A, B, C) injection molding machine into (20) by semi-molten resin (M _1, M _2, which is formed out with 2c),
M ₃₎ was injected and filled in the mold press forming process of multi-cavity for mold press forming a plurality of molded articles, the plurality of cavity mold (33a, 33b, 33c)
Is provided with a shock absorber between the mounting plate (32), and the shock absorbing action of the shock absorber absorbs variation in the amount of resin supplied to the cavities (A, B, C), and the cavity (A,
A mold press molding method characterized in that the internal pressures (B, C) are controlled substantially uniformly. 2. A single molded product is obtained by injection filling a semi-molten resin from an injection molding machine (20) into a cavity (A) formed by a single cavity mold (33) and a core mold (42). In the mold press molding method, a buffer device is provided between the cavity mold (33) and the mounting plate (32), and the buffer action of the buffer device causes the resin distribution in the cavity (A) to be reduced. A mold press molding method characterized by absorbing variations and controlling the internal pressure of the cavity (A) almost uniformly. 3. An upper and lower mold (30, 4) for mold press molding for forming a desired cavity (A, B, C) space.
0), an injection molding machine (20) for distributing and supplying the resin material into the cavities (A, B, C) through a gate (44) formed in the lower mold (40); A mold press molding die, comprising: a mounting device (32) in a die (30); and a shock absorber inserted between a cavity die (33a, 33b, 33c). 4. The cushioning device according to claim 1, wherein the cushioning device comprises a cushion rubber (3).
4. The mold for mold press molding according to claim 3, wherein the mold comprises: 5. The mold press molding die according to claim 3, wherein the shock absorbing device is formed by a spring such as a spring (37) or a spring-like member. 6. The shock absorber according to claim 6, wherein the shock absorber is a hydraulic damper.
4. The mold for mold press molding according to claim 3, wherein: