JPH06106581A - Mold for molding - Google Patents

Abstract

PURPOSE:To provide a mold capable of obtaining moldings with excellent finishing accuracy without causing any deformation or damages of mold by molding objects to be molded at a constant pressure suitable to the molding conditions of the objects to be molded. CONSTITUTION:In the mold 2, a molding space 5 is defined by a movable side core 7 and a mold plate 8 and a stationary side mold plate 17. In the core 7, a communicating bore 32 is formed which can communicate with the molding space 5 and outer space. A valve unit 31 is detachably secured to the communicating bore 32. The valve unit 31 is provided with an escape valve mechanism and the escape valve mechanism is actuated when pressure in the molding space 5 reaches the preset valve opening pressure, it acts to open the valve 33 and exclude, i.e., resin within the molding space 5 via an escape hole 40 and the communication hole 32 to the outside space.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding die for injecting a molding object into a molding space formed by at least two mold parts, such as an injection molding machine. The present invention relates to a molding die in which an excessive pressure is not applied to a space.

[0002]

2. Description of the Related Art For example, a conventional molding die _2a used in an injection molding machine is shown in FIG. In the molding die 2 _a , the molding space 5 _a is formed by the mold plate 17 _a fixed to the main body of the injection molding machine, the core 7 _a and the mold plate 8 integrally attached to the receiving plate 12. ing. The aforementioned molding space 5 within _a, the molded product such as a synthetic resin is molded by injection at a predetermined pressure. By the way, the molding conditions for molding the above-mentioned molded object are not known from the beginning, and a plurality of preliminary molding operations are repeated by trial and error, and based on the results of these operations, the molding conditions for the above-mentioned molded object are molded. A product suitable for mass production is determined.

[0003]

[SUMMARY OF THE INVENTION However, when the injection pressure more than necessary in the molding space 5 within _a is applied, compared with the mold plate 17 _a which is fixed to the main body, a rigid provided on the movable side The lower template 8 and the backing plate 12 may bend as shown by the chain double-dashed line in FIG. On the other hand, the molding die 2 shown in FIG.
_{As shown by b} , when a molding space 5 _b formed by the mold plate 8 and the core 7 _b and the mold plate 17 _b is subjected to an excessive injection pressure,
For example, a depression portion A may be formed in the template 8 due to the high-pressure molded object. As described above, when the template 8 and the receiving plate 12 are bent or the depressions A are formed in the template 8 or the like, burrs or the like are generated in the finished molded product. Then, the molding space 5 _a, 5 when the injection pressure applied to _b is extremely excessive, the mold plate 8, to cause breakage of 12 such backing plate is a concern. Therefore, an object of the present invention is to form a molded product with a constant pressure suitable for the molding conditions of the molded product, without causing deformation or breakage of the molding die, and with good finish accuracy. An object of the present invention is to provide a molding die capable of obtaining a product.

[0004]

In order to achieve the above-mentioned object, the main means adopted by the present invention is, in essence, the injection of an object to be molded into a molding space formed by at least two or more mold parts. In at least one of the mold parts to be molded by forming a communicating hole that communicates the molding space with the outside, the pressure of the molding space becomes a preset pressure in the communication hole. It is configured as a molding die characterized in that a relief valve mechanism for opening the valve is provided. Further, as the relief valve mechanism, it is also possible to adopt a configuration provided in a valve unit detachably attached to the communication hole. Further, the relief valve mechanism may be configured so that the pressure for opening the relief valve mechanism can be changed.

[0005]

In the molding die according to the present invention, at least 2
When the pressure in the molding space formed by three or more mold parts reaches a preset pressure, the relief valve mechanism opens. As a result, the object to be molded in the molding space is discharged to the outside from the molding space through the relief valve mechanism and the communication hole. At this time, the pressure set in the relief valve mechanism is set to, for example, a pressure that does not cause deformation or breakage of the mold parts, so that a molded product of a molded product having a high finishing accuracy can be obtained. Further, in the case where the relief valve mechanism is arranged in a valve unit detachably attached to the communication hole of the mold part, for example, when a failure occurs in the relief valve mechanism, the valve unit is integrally replaced. It is possible and extremely convenient. When the relief valve mechanism is configured so that the pressure for opening the relief valve mechanism can be changed, the pressure in the molding space suitable for molding the molding target, which varies depending on the type of the molding target, is variably adjusted. can do. Further, the pressure of the molding space can be set and changed to a pressure that does not cause deformation or loss of the mold parts.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying the present invention will be described below with reference to the accompanying drawings for the understanding of the present invention. It should be noted that the following embodiments are examples of embodying the present invention, and are not intended to limit the technical scope of the present invention. here,
FIG. 1 shows a valve unit used in a molding die of an injection molding machine according to an embodiment of the present invention, (a) is a side sectional view of the valve unit, and (b) is an external view of the valve unit. 2 is a side sectional view showing a molding die of the injection molding machine, FIG. 3 is a side sectional view showing a mounting state of a valve unit mounted on the molding die, and FIG. 4 is a valve of the valve unit opened. It is a state explanatory view showing a state. FIG. 1 shows a valve unit 31 for maintaining the pressure in the molding space formed in the molding die of the injection molding machine according to this embodiment at a pressure equal to or lower than a preset pressure. The valve unit 31 is mainly composed of a cylindrical casing 51 formed with a relief hole 40 penetrating in the cylinder core direction, and a relief valve mechanism 30 arranged in the casing 51. A female screw portion 37 is formed on the inner wall of the escape hole 40 of the casing 51. A male screw portion 38 is engraved on the outer periphery of the casing 51. The relief valve mechanism 30 includes a valve 33 that opens and closes the relief hole 40 by releasably engaging a taper portion formed at an end of the relief hole 40 of the casing 51, and the valve 33 in the cylinder core direction. A coil spring 34 that constantly urges (in the valve closing direction indicated by arrow D ₂ ) and a spring support portion 3 that supports the coil spring 34.
It consists of 5. On the outer periphery of the spring support portion 35,
A male thread portion 36 that is screwed into the female thread portion 37 of the relief hole 40.
Is engraved. A hexagonal groove 42 is formed on the surface of the spring support portion 35 that faces the support surface of the coil spring 34. A hexagon wrench (not shown), for example, for adjusting the fixed position in the axial direction by rotating the spring support portion 35 around the axial center is engaged with the hexagonal groove 42. The escape hole 40 on the side of the hexagonal groove 42 and the coil spring 3
A communication hole 43, which communicates with the escape hole 40 on the fourth side, is formed in the spring support portion 35.

FIG. 2 shows a molding die 2 of the injection molding machine 1 in which the valve unit 31 is arranged. In the drawing, in the molding die 2 of the injection molding machine 1, a molding plate 17 (an example of molding parts) is provided on a side surface of a mounting plate 9 fixed to a molding machine body (not shown).
Is fixed. A molten synthetic resin M (an example of an object to be molded) is formed in the central portion of the mounting plate 9 and the template 17 in the vertical direction.
A sprue bush 10 having a horizontal guide pipe 3 for guiding the inside of the molding die 2 is provided so as to penetrate the mounting plate 9 and the mold plate 17. The sprue bush 10 is fixed to the mounting plate 9 via a positioning ring 22. Then, the positioning ring 22 that becomes the end of the guide pipe 3 is formed.
The tip of the nozzle 4 which houses the synthetic resin M therein is positioned and connected to the corresponding position by the positioning ring 22. The mounting plate 14, which is movable with respect to the mounting plate 9 and the like, has a spacer block 13, a receiving plate 12, and a molding plate 8 in that order toward the molding plate 17.
(Example of mold parts) is integrally provided. The template 8 and the receiving plate 12 are fastened by bolts or the like (not shown). The mounting plate 1 in the spacer block 13
A take-out plate 16 and a take-out plate 15, which are integrally provided, are provided between 4 and the receiving plate 12 so as to be movable in the arrow D ₁ direction and the opposite direction. Drive shaft 41 which is fixed to the side of the arrow D ₁ direction downstream side of the take-out plate 16 is slidably supported on the opposite to the arrow D ₁ direction in the mounting plate 14. By driving the drive shaft 41, the take-out plates 15 and 16 are driven in the spacer block 13. Further, on the upper side surface of the receiving plate 12 on the upstream side in the arrow D ₁ direction, a synthetic resin M
A core 7 (an example of a mold part) that becomes a part of the mold at the time of molding is integrally provided. A guide pin 19 guided in the guide bush 25 of the template 17 is provided on the lower side surface of the receiving plate 12. The core 7 and the guide pin 19 penetrate the template 8 and project toward the template 17. And, on the side surface of the take-out plate 16,
From the top, a protruding pin 20, a sprue lock pin 21, and a return pin 18 are provided so as to project toward the template 8 and are respectively supported by a take-out plate 15. These protruding pins 20,
The sprue lock pin 21 and the return pin 18 are slidably supported by the receiving plate 12, the template 8 or the core 7, respectively, and the tips of the sprue lock pin 21 and the return pin 18 project from the core 7 or the template 8 toward the template 17. It is possible. In the molding die 2, with the take-out plate 16 in close contact with the mounting plate 14, the mounting plate 14 to the mold plate 8 are integrally driven toward the fixed-side mold plate 17 to join the mold plates 8. The surface F and the joint surface G of the template 17 are in close contact with each other. At this time, between the template 17, the core 7 and the template 8,
A molding space 5 for the synthetic resin M and a communication conduit 6 for communicating the molding space 5 with the guide conduit 3 are formed.

In the molding die 2, in particular, a communication hole 32 that communicates the molding space 5 with the external space is formed through the core 7 and the receiving plate 12. Further, the valve unit 31 is arranged in the communication hole 32.
On the inner wall of the communication hole 32 of the receiving plate 12 and the mold plate 8, a female screw portion 39 that is screwed into the male screw portion 38 of the valve unit 31 is engraved. Further, the male thread portion 38 has the female thread portion 3
When the valve unit 31 is screwed in the state of being screwed into the valve 9, the valve unit 31 is fixed at a position near the molding space 5 of the communication hole 32 (see FIG. 3). The strength of each part of the molding die 2 is calculated based on the resin pressure in the molding space 5 when the injection molding machine 1 is driven, which is set for each synthetic resin type of the synthetic resin M. The resin pressure representative value in the molding space 5 set for each synthetic resin type is shown below. However, the unit for expressing the numerical values shown below is kg / cm ² . PS resin 400 ABS resin 400 PP resin 300 PC resin 500 POM resin 800 The valve opening pressure preset in the relief valve mechanism 30 of the valve unit 31 differs depending on the synthetic resin type of the synthetic resin M, for example, the strength of each part. The above resin pressure used for calculation +5
It is 10 (kg / cm ² ). In this way, the valve opening pressure of the relief valve mechanism 30 that differs for each synthetic resin type is adjusted by screwing the spring support portion 35 in a state where the male screw portion 36 and the female screw portion 37 are screwed together, and the spring for the casing 51. The setting can be changed by adjusting the mounting position of the support portion 35 in the axial direction. When molding the synthetic resin M in the injection molding machine 1 as described above, the mold plate 17, the core 7 and the mold plate 8 are the molding space 5 of the synthetic resin M, the molding space 5 and the guide pipe line. 3 are arranged in a positional relationship that forms 3.

Then, the synthetic resin M melted in the high temperature nozzle 4 is injected from the tip of the nozzle 4 into the molding space 5 of the molding die 2 at a predetermined injection pressure through the guide conduit 3. At this time, when the injection pressure of the synthetic resin M is higher than the valve opening pressure preset in the relief valve mechanism 30 of the valve unit 31, the synthetic resin M in the molding space 5 is
As shown in FIG. 4, the valve 33, which is constantly biased by the coil spring 34, is pushed back in the direction opposite to the arrow D ₂ . As a result, the valve unit 31 opens. Therefore, the high-pressure synthetic resin M in the molding space 5 flows into the casing 51 from the relief hole 40 on the valve 33 side, and further, the communication hole 43, the relief hole 40 on the hexagonal groove 42 side, and the communication on the molding die 2 side. It is discharged to the external space through the hole 32. When the pressure of the synthetic resin M in the molding space 5 falls below the valve opening pressure, the spring 34 pushes up the valve 33 against the injection pressure at that time to close the valve. As described above, the molding die 2 of this embodiment
According to the method, each synthetic resin can be molded at a constant injection pressure suitable for the molding condition for each synthetic resin type.
This prevents the parts of the molding die 2 from being deformed or damaged. As a result, it is possible to obtain a molded product of each synthetic resin with excellent finishing accuracy and to improve the product yield. As described above, since it is not necessary to worry about the breakage of each part of the molding die 2, the condition setting for determining the molding condition of the synthetic resin becomes extremely easy. That is, the optimum molding conditions for the synthetic resin can be determined without resorting to highly skilled workers. Further, since the upper limit value of the injection pressure in the molding space 5 can be regulated by the valve unit 31, it is possible to mold the synthetic resin by a pressure feedback method in the molding space which is often used as a precision molding method.
Moreover, the relief valve mechanism 30 can set and change the injection pressure suitable for each synthetic resin for each synthetic resin type. Further, since the valve unit 31 is detachably attached to the molding die 2, even if any type of molding die is provided, a communication hole capable of removably attaching the valve unit 31 may be simply formed. For example, it can be used as a standard part.
In addition, in the above-mentioned embodiment, the example in which the communication hole 32 for mounting the valve unit 31 is formed in the core 7 and the receiving plate 12 is shown, but the present invention is not limited to this, and the external space and the molding space 5 are The communication holes that communicate with each other may be formed at the positions of the template 8 and the template 17 that do not cause a problem in function and quality of the molded product.

[0010]

According to the present invention, in a molding die for injecting an object to be molded into a molding space formed by at least two or more mold parts, at least one of the mold parts has the molding space and the outside. There is provided a molding die characterized in that a communication hole for communicating with and is formed, and a relief valve mechanism that opens the valve when the pressure in the molding space reaches a preset pressure is provided in the communication hole. It As a result, the molding target can be molded at a constant molding pressure suitable for the molding conditions of the molding target. Therefore, the molding die is not deformed or broken. As a result, it is possible to obtain a molded product having excellent finish accuracy related to the molded product.

[Brief description of drawings]

FIG. 1 shows a valve unit used in a molding die of an injection molding machine according to an embodiment of the present invention, (a) is a side sectional view of the valve unit, and (b) is an external view of the valve unit.

FIG. 2 is a side sectional view showing a molding die of the injection molding machine.

FIG. 3 is a side sectional view showing a mounting state of a valve unit mounted on the molding die.

FIG. 4 is a state explanatory view showing a state in which a valve of the valve unit is opened.

FIG. 5 is a side sectional view showing a main part of a conventional molding die which is an example of the background of the present invention.

FIG. 6 is a side sectional view showing a main part of a conventional molding die which is another example of the background of the present invention.

[Explanation of symbols]

2, 2 _a , 2 _b ... Molding die 5, 5 _a , 5 _b ... Molding space 7, 7 _a , 7 _b ... Core (molding component) 8 ... Template (molding component) 17, 17 _a , 17 _b ... Template (mold component) 30 ... Relief valve mechanism 31 ... Valve unit 32 ... Communication hole 33 ... Valve 34 ... Coil spring 35 ... Spring support 36 ... Male thread 37 ... Female thread 38 ... Male thread 39 ... Female thread 40 ... Relief hole 42 ... Hexagonal groove M ... Synthetic resin (object to be molded)

Claims (3)

[Claims] 1. A molding die for injecting an object to be molded into a molding space formed by at least two or more mold parts, wherein at least one mold part has a communication hole for communicating the molding space with the outside. And a relief valve mechanism that opens the valve when the pressure in the molding space reaches a preset pressure in the communication hole. 2. The molding die according to claim 1, wherein the relief valve mechanism is provided in a valve unit detachably attached to the communication hole. 3. The molding die according to claim 1, wherein the relief valve mechanism is configured so that the pressure for opening the relief valve mechanism can be changed.