CN114211678A - Injection compression molding mold and plastic part molding method - Google Patents

Abstract

The invention discloses an injection compression molding die and a plastic part molding method.A preset distance is arranged between a parting block and a core seat plate during injection molding, so that the thickness of an injection compression cavity is kept thicker, and the injection pressure is not increased; after the injection has been completed for a certain period, i.e. before the injection compression chamber is completely filled with injection material, the injection is stopped. Then, the distance between the parting block and the core seat plate is shortened to reduce the thickness of the injection compression cavity, and the plastic part in the injection compression cavity is compressed to be thin. The advance of the core insert is controllable, and plastic parts with different thicknesses can be formed along with the continuous change of the advance distance of the core insert.

Description

Injection compression molding mold and plastic part molding method

Technical Field

The invention relates to the technical field of automobile plastic part manufacturing, in particular to an injection compression molding die and a plastic part molding method.

Background

With the increasing competition of automobile sales, how to reduce the weight of the automobile as much as possible, improve the power utilization rate of the automobile and reduce the fuel consumption becomes the core of the competition of each large automobile enterprise. The plastic parts account for a considerable portion of the interior of the automobile, and the weight reduction of the plastic parts contributes considerably to the weight reduction of the automobile. Therefore, how to make the wall thickness of the product the thinnest is the direction of a major hot spot of light weight under the condition of meeting the performance of the plastic parts. However, if the wall thickness of the plastic part is reduced, a greater filling pressure is required during injection molding, which increases the tonnage of the injection molding apparatus, and flash may be present at the edge of the part.

In view of the above, it is necessary to provide an injection compression molding die and a plastic part molding method that can reduce the thickness of a plastic part and facilitate molding of a thin plastic part.

Disclosure of Invention

The invention aims to provide an injection compression molding die and a plastic part molding method, which can reduce the thickness of a plastic part and facilitate the molding of the thin plastic part.

The technical scheme of the invention provides an injection compression molding die which comprises a lower die base, a core arranged on the lower die base and a cavity positioned above the core;

the core comprises a core seat plate and a core insert block on the core seat plate;

the core insert, the core seat plate and the lower die seat are connected through a pull rod;

an injection compression cavity is formed between the core insert and the cavity;

the periphery of the core seat plate is provided with parting blocks, and the parting blocks surround the outer side of the core insert;

elastic pieces are arranged on the core base plate and the parting block, and a preset distance is reserved between the bottom surface of the parting block and the top surface of the core base plate in an initial state;

the top surface of the parting block is kept in contact and sealed with the bottom surface of the cavity;

during injection molding, the preset distance is kept between the core seat plate and the parting block;

when the compression mold is compressed, the lower die holder, the core seat plate and the core insert integrally move towards the side of the mold cavity, the distance between the core seat plate and the parting block is reduced, and the thickness of the injection compression cavity is reduced.

In one optional technical solution, the elastic member is a spring.

In an alternative embodiment, a plurality of elastic elements are uniformly distributed between the core seat plate and the parting block.

In one optional technical scheme, the injection molding is stopped and the compression is started when the injection molding process is finished by 60-80%.

In one optional technical scheme, the top surface of the core seat plate is provided with a seat plate groove, and the bottom surface of the parting block is provided with a parting block groove;

the upper end of the elastic piece is positioned in the parting block groove, and the lower end of the elastic piece is positioned in the seat plate groove.

In one optional technical scheme, the lower die holder is pushed by an injection molding machine during compression.

In one optional technical scheme, in an initial state, the maximum thickness of the injection compression cavity is D; after compression, the maximum thickness of the injection compression cavity is between 0.6D and 0.8D.

In an optional technical scheme, the core insert, the core seat plate and the lower die seat are connected through a plurality of pull rods.

In one optional solution, a positioning member is connected between the core insert and the core seat plate.

The technical scheme of the invention provides a plastic part forming method for forming a plastic part by adopting the injection compression forming mould of any one technical scheme, which comprises the following steps:

s01: when the injection compression molding mold is in an initial state, injecting injection molding materials into the injection compression cavity;

s02: stopping injection molding when the injection molding process is finished by 60-80%;

s03: the lower die holder, the core seat plate and the core insert are pushed to integrally move towards the cavity side, the distance between the core seat plate and the parting block is reduced, and the thickness of the injection molding compression cavity is reduced;

s04: and finishing the injection compression molding of the plastic part, pulling the lower die holder to drive the mold core to be separated from the mold cavity, and taking down the plastic part.

By adopting the technical scheme, the method has the following beneficial effects:

according to the injection compression molding die and the plastic part molding method provided by the invention, during injection molding, the preset distance is reserved between the parting block and the core seat plate, so that the thickness of an injection compression cavity is kept thicker, and the injection pressure is not increased; after the injection has been completed for a certain period, i.e. before the injection compression chamber is completely filled with injection material, the injection is stopped. Then, the distance between the parting block and the core seat plate is shortened to reduce the thickness of the injection compression cavity, and the plastic part in the injection compression cavity is compressed to be thin. The advance of the core insert is controllable, and plastic parts with different thicknesses can be formed along with the continuous change of the advance distance of the core insert.

Drawings

The disclosure of the present invention will become more readily understood by reference to the drawings. It should be understood that: these drawings are for illustrative purposes only and are not intended to limit the scope of the present disclosure. In the figure:

fig. 1 is a schematic structural diagram of an injection compression molding mold according to an embodiment of the present invention;

FIG. 2 is a schematic view of the parting block being spaced a predetermined distance from the bottom surface of the core plate in an initial state;

FIG. 3 is a schematic illustration of the core insert moving upward to reduce the thickness of the injection compression cavity.

Detailed Description

The following further describes embodiments of the present invention with reference to the accompanying drawings. In which like parts are designated by like reference numerals. It should be noted that the terms "front," "back," "left," "right," "upper" and "lower" used in the following description refer to directions in the drawings, and the terms "inner" and "outer" refer to directions toward and away from, respectively, the geometric center of a particular component.

As shown in fig. 1 to 3, an injection compression molding mold according to an embodiment of the present invention includes a lower mold base 1, a core 2 mounted on the lower mold base 1, and a cavity 3 located above the core 2.

The core 2 includes a core seat plate 21 and a core insert 22 on the core seat plate 21.

The core insert 22, the core seat plate 21 and the lower die holder 1 are connected by a tie rod 6.

An injection compression cavity 8 is formed between the core insert 22 and the cavity 3.

Wherein, the parting block 4 is arranged on the periphery of the core seat plate 21, and the parting block 4 is surrounded on the outer side of the core insert 22.

The elastic piece 5 is arranged on the core seat plate 21 and the parting block 4, and a preset distance is reserved between the bottom surface of the parting block 4 and the top surface of the core seat plate 21 in an initial state.

The top surface of the parting block 4 remains in contact seal with the bottom surface of the mould cavity 3.

During injection molding, a preset distance is kept between the core seat plate 21 and the parting block 4.

During compression, the lower die holder 1, the core holder plate 21 and the core insert 22 integrally move towards the cavity 3, the distance between the core holder plate 21 and the parting block 4 is reduced, and the thickness of the injection compression cavity 8 is reduced.

The injection compression molding die provided by the embodiment of the invention is used for molding plastic parts of automobiles. The injection compression molding die comprises a lower die holder 1, a core 2, a cavity 3, a parting block 4 and an elastic piece 5.

When the injection molding machine is used, the lower die holder 1 is connected with an injection molding machine and is a movable die. The core 2 is arranged on the lower die base 1. The cavity 3 is positioned above the core 2, and the cavity 3 is arranged on the fixed die.

The core 2 is composed of a core seat plate 21 and a core insert 22. The core insert 22 is located on a core seat plate 21 which is convex towards the cavity 3 so that an injection compression chamber 8 is formed between the core insert 22 and the cavity 3. The core insert 22, the core seat plate 21 and the lower die holder 1 are connected into a whole through a pull rod 6.

The parting block 4 is provided on the peripheral edge of the core seat plate 21, and the parting block 4 is in the form of a ring which surrounds the outside of the core insert 22. The parting block 4 is connected with the die cavity 3 through a connecting structure, so that the top surface of the parting block 4 is kept in contact with the bottom surface of the die cavity 3 to seal the injection compression cavity 8.

The core base plate 21 and the parting block 4 are mounted with elastic members 5. In the initial state, the bottom surface of the parting block 4 is spaced from the top surface of the core seat plate 21 by a predetermined distance under the action of the elastic member 5. The preset distance can be adjusted as required to keep the thickness of the injection compression cavity 8 in a relatively thick state.

When the injection compression molding mold is used for injection molding of plastic parts, the preset distance is kept between the core seat plate 21 and the parting block 4, namely the injection compression molding mold is kept in an initial state, so that the thickness of the injection compression cavity 8 is kept thicker, and the injection pressure is not increased. After a certain period of injection, i.e. before the injection compression chamber 8 is completely filled with injection material, the injection is stopped. Then the lower die holder 1, the core seat plate 21 and the core insert 22 are pushed to integrally move towards the side of the cavity 3 so as to reduce the distance between the core seat plate 21 and the parting block 4, further reduce the thickness of the injection compression cavity 8, compress the plastic part in the injection compression cavity 8 and thin the plastic part, and the thickness of the plastic part can be thinned to be less than 1mm without flash. The advancement of the core insert 22 is controlled to mold plastic parts of different thicknesses as the distance of advancement of the core insert 22 is varied.

In some cases, the core plate 21 is pushed into contact with the parting block 4, where the thickness of the injection compression chamber 8 is at a minimum and the molded plastic part is the thinnest.

In one embodiment, as shown in fig. 1, the elastic member 5 is a spring, which has good elastic effect and is convenient to arrange.

In one embodiment, a plurality of elastic members 5 are uniformly distributed between the core seat plate 21 and the parting block 4, and the supporting force for the parting block 4 is improved to maintain the distance between the core seat plate 21 and the parting block 4.

In one embodiment, the injection is stopped and compression is started at 60-80% of the injection process. 60-80% can be calculated according to the volume of the injection compression cavity 8, for example, the initial volume of the injection compression cavity 8 is V, and when the volume of the injection molding material liquid injected into the injection compression cavity 8 reaches 0.6V-0.6V, the injection molding is stopped, so as to avoid the thickness of the plastic part from exceeding the preset thickness. Because the initial volume V already exceeds the volume of injection molding material liquid required for the plastic part itself, it is difficult to compress to the desired thickness of the plastic part if the initial volume V is filled completely.

In one embodiment, as shown in FIG. 1, the top surface of core plate 21 has a plate recess 211 and the bottom surface of parting block 4 has a parting block recess 41. The upper end of the elastic member 5 is positioned in the parting block groove 41, and the lower end of the elastic member 5 is positioned in the seat plate groove 211, which is beneficial to improving the installation stability of the elastic member 5.

In one embodiment, the lower die holder 1 is pushed by an injection molding machine during compression. When the core 2 is pulled open, the injection molding machine pulls the core 2 and the lower die holder 1 to integrally move, so that the core 2 is separated from the cavity 3, and a formed plastic part can be taken down.

In one embodiment, the maximum thickness of the injection compression chamber 8 is D in the initial state. After compression, the maximum thickness of the injection-molded compression chamber 8 is between 0.6D and 0.8D, and thus the maximum thickness D1 of the molded plastic part is between 0.6D and 0.8D.

In one embodiment, as shown in fig. 1, the core insert 22, the core seat plate 21 and the lower die holder 1 are connected through a plurality of pull rods 6, so that the assembly stability among the core insert 22, the core seat plate 21 and the lower die holder 1 is improved.

In one embodiment, as shown in figure 1, a spacer 7 is connected between the core insert 22 and the core seat plate 21. During assembly, the core insert 22 and the core seat plate 21 can be connected into an integral structure through the positioning piece 7, and the assembly with the lower die holder 1 is facilitated.

Referring to fig. 1 to 3, an embodiment of the present invention provides a plastic part molding method for molding a plastic part by using the injection compression molding die according to any one of the foregoing embodiments, including the following steps:

s01: in the initial state of the injection compression molding die, the injection compression cavity 8 is filled with an injection molding material.

S02: and stopping injection molding when the injection molding process is finished by 60-80%.

S03: the lower die holder 1, the core seat plate 21 and the core insert 22 are pushed to integrally move towards the side of the cavity 3, the distance between the core seat plate 21 and the parting block 4 is shortened, and the thickness of the injection molding compression cavity 8 is reduced.

S04: and (3) finishing the injection compression molding of the plastic part, pulling the lower die holder 1 to drive the mold core 2 to be separated from the mold cavity 3, and taking down the plastic part.

When the injection compression molding mold is used for injection molding of plastic parts, the preset distance is kept between the core seat plate 21 and the parting block 4, namely the injection compression molding mold is kept in an initial state, so that the thickness of the injection compression cavity 8 is kept thicker, and the injection pressure is not increased. After a certain period of injection, i.e. before the injection compression chamber 8 is completely filled with injection material, the injection is stopped, for example, when the injection process is completed by 60-80%. Then the lower die holder 1, the core seat plate 21 and the core insert 22 are pushed to integrally move towards the side of the cavity 3 so as to reduce the distance between the core seat plate 21 and the parting block 4, further reduce the thickness of the injection compression cavity 8, compress the plastic part in the injection compression cavity 8 and thin the plastic part, and the thickness of the plastic part can be thinned to be less than 1mm without flash. The advancement of the core insert 22 is controlled to mold plastic parts of different thicknesses as the distance of advancement of the core insert 22 is varied. In some cases, the core plate 21 is pushed into contact with the parting block 4, where the thickness of the injection compression chamber 8 is at a minimum and the molded plastic part is the thinnest.

And after standing for a preset time, completing injection and compression molding of the plastic part, pulling the lower die holder 1 to drive the mold core 2 to be separated from the mold cavity 3, and taking down the plastic part.

According to the needs, the above technical schemes can be combined to achieve the best technical effect.

The foregoing is considered as illustrative only of the principles and preferred embodiments of the invention. It should be noted that, for those skilled in the art, several other modifications can be made on the basis of the principle of the present invention, and the protection scope of the present invention should be regarded.

Claims (10)

1. The injection compression molding die is characterized by comprising a lower die base, a core arranged on the lower die base and a cavity positioned above the core;

the core comprises a core seat plate and a core insert block on the core seat plate;

the core insert, the core seat plate and the lower die seat are connected through a pull rod;

an injection compression cavity is formed between the core insert and the cavity;

the periphery of the core seat plate is provided with parting blocks, and the parting blocks surround the outer side of the core insert;

elastic pieces are arranged on the core base plate and the parting block, and a preset distance is reserved between the bottom surface of the parting block and the top surface of the core base plate in an initial state;

the top surface of the parting block is kept in contact and sealed with the bottom surface of the cavity;

during injection molding, the preset distance is kept between the core seat plate and the parting block;

when the compression mold is compressed, the lower die holder, the core seat plate and the core insert integrally move towards the side of the mold cavity, the distance between the core seat plate and the parting block is reduced, and the thickness of the injection compression cavity is reduced.

2. An injection compression molding mold as claimed in claim 1, wherein the elastic member is a spring.

3. The injection compression molding mold of claim 1, wherein a plurality of the elastic members are evenly distributed between the core seat plate and the parting block.

4. An injection compression molding mold as claimed in claim 1, wherein the compression is started by stopping the injection at 60-80% of the completion of the injection process.

5. The injection compression molding mold as claimed in claim 1, wherein the top surface of the core plate has a plate groove and the bottom surface of the parting block has a parting block groove;

the upper end of the elastic piece is positioned in the parting block groove, and the lower end of the elastic piece is positioned in the seat plate groove.

6. The injection compression molding mold of claim 1, wherein the lower mold base is pushed by an injection molding machine during compression.

7. An injection compression molding mold as claimed in claim 1, wherein the maximum thickness of the injection compression cavity in an initial state is D; after compression, the maximum thickness of the injection compression cavity is between 0.6D and 0.8D.

8. The injection compression molding mold of claim 1, wherein the core insert, the core shoe and the lower shoe are connected by a plurality of tie rods.

9. An injection compression molding mold as claimed in claim 1 wherein a locating member is connected between the core insert and the core seat plate.

10. A plastic part molding method for molding a plastic part using the injection compression molding die according to any one of claims 1 to 9, comprising the steps of:

s01: when the injection compression molding mold is in an initial state, injecting injection molding materials into the injection compression cavity;

s02: stopping injection molding when the injection molding process is finished by 60-80%;

s03: the lower die holder, the core seat plate and the core insert are pushed to integrally move towards the cavity side, the distance between the core seat plate and the parting block is reduced, and the thickness of the injection molding compression cavity is reduced;

s04: and finishing the injection compression molding of the plastic part, pulling the lower die holder to drive the mold core to be separated from the mold cavity, and taking down the plastic part.

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