JP2539543B2 - Injection mold - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an injection molding die such as a resin molding die for injection molding a target product by utilizing the thermoplasticity of a resin. .

[Conventional technology]

In the injection mold, basically, the fixed side mounting plate that is mounted on the fixed side of the molding machine, the fixed side mold plate that is mounted on this fixed side mounting plate, and the fixed side mold plate through the guide pin. A movable side template that is guided oppositely, a receiving plate that supports the movable side template, a movable side mounting plate that is mounted on the movable side of the molding machine, and a spacer that is provided between the movable side mounting plate and the receiving plate. The block is provided with an ejector plate or the like provided in a space formed by the spacer block.

And conventionally, each component such as the fixed side template or the movable side template is formed of a steel material such as carbon steel for machine structure,
In recent years, attempts have been made to use lightweight metals such as aluminum for some of the constituent members.

[Problems to be Solved by the Invention]

By the way, in resin injection molding, for example, in the case of polystyrene, the resin temperature is 200 to 300 ° C. and the injection pressure is 800.
The molding conditions are ~ 2000 (kg / cm ² ). Further, since the resin pressure injected into the cavity acts in the direction of opening the mold, the mold clamping force must exceed the above injection pressure from the viewpoint of avoiding defective molded products such as burrs.

Therefore, heat resistance and pressure resistance are strongly required as the constituent members of the mold, and steel materials are used to cope with these requirements.

In other words, in this field, from the structural aspect,
As you can see in the so-called cassette type mold where only the main part of the molding is exchanged, stepwise development can be seen, but from the material side,
Steel is highly rigid as a material that can maintain dimensional accuracy by satisfying strength conditions such as heat resistance and pressure resistance, and it is currently under the stereotype that other materials cannot maintain dimensional accuracy. .

Therefore, there are various inconveniences in terms of handling. That is, for example, the external dimensions in the injection state are 200 mm
In the case of x 230 mm x 260 mm, the weight is about 70 kg to 80 kg,
In terms of dimensions, it is extremely difficult to move by hand even though it is small. For this reason, a mechanical transfer means such as a chain block is indispensable, and in the case of a large mold, the transfer means is required to be large in size, resulting in an increase in equipment cost.

In addition, the smoothness is hindered by the weight during replacement / installation work on the molding machine and handling in the distribution process,
This leads to higher work costs and distribution costs.

In addition, this type of mold requires preheating of the mold prior to injection in order to avoid defective molding due to temperature differences, but heat transfer to the molding machine occurs because the components are made of metal. The mold temperature is unstable, which adversely affects the molding. Therefore, a heat insulating material such as bakelite is interposed between the movable side mounting plate and the molding machine.

Furthermore, in this type of mold, a cooling water passage is provided in the mold for forced cooling, but since the constituent members of the metal material come into direct contact with the cooling water, once the use is finished, Since it is stored for a long period of time, it causes deterioration of its aesthetic appearance due to rust.

Therefore, an object of the present invention is to provide a mold that can be reduced in weight, can obtain a heat insulating function, and can be rust-prevented.

[Means for solving the problem]

In order to achieve the above object, the present invention employs the following means.

That is, in claim 1, the member forming the injection path from the sprue bush to the cavity is made of steel, and at least the cavity surrounding member that supports the member forming the cavity that is a part of the injection path is made of a lightweight metal material such as aluminum. And the members constituting the injection path and the members other than the cavity surrounding member are made of a synthetic resin material.

According to a second aspect, in the injection molding die according to the first aspect, the member forming the cavity is composed of a core and a piece member, and the cavity surrounding member is formed by fitting a core mounting plate to which the core is fitted and a piece member. And a piece mounting plate.

According to a third aspect of the present invention, in the injection molding die according to the second aspect, the core is assembled to the core mounting plate and the core mounting plate is assembled to the stationary side template by a stepped fitting structure, and the piece member is mounted on the piece. The piece mounting plate is attached to the movable side template with a stepped fitting structure.

[Action]

According to this means, in claim 1, the member constituting the injection path from the sprue bush to the cavity, which is required to have a high degree of heat resistance, pressure resistance, rigidity, etc., is made of steel material as in the conventional case. Part of the cavity, which is made of a lightweight metal material such as aluminum to support the members that make up the cavity, which are affected by the heat and pressure associated with injection, is made of lightweight metal such as aluminum to reduce heat resistance, pressure resistance, rigidity, and weight reduction. It is in harmony with rust prevention. Moreover, members other than the member forming the injection path and the member around the cavity are made of a synthetic resin material to further reduce the weight and prevent rust.

In the second aspect, the member forming the injection path and the cavity surrounding member are the core of the fitting structure, the piece member, the core mounting plate, and the piece mounting plate.

In the third aspect, the cores made of different materials, the piece member and the core mounting plate, the piece mounting plate and the fixed side mold plate, and the movable side mold plate are securely assembled in a stepped fitting structure.

〔Example〕

 1 and 2 show an embodiment of the present invention.

This is an example of a three-plate type with four gears. The mold 2 is provided with a fixed side attachment plate 4 attached to the fixed side of a molding machine (not shown) and a movable side attachment plate 6 attached to the movable side. The fixed side attachment plate 4 has a parting line PL. A runner stripper plate 8 and a fixed-side template 10 are provided in this order.

A locating ring 12 and a runner lock pin support plate 14 are integrally incorporated in the fixed side mounting plate 4, and a runner lock pin guide 16 is incorporated in the runner stripper plate 8. The sprue bushes and runners are omitted. Further, a core 18, a core mounting plate 20, and a runner plate 22 are integrally incorporated in the stationary mold plate 10.

The movable side mounting plate 6 is provided with spacer blocks 24, 24, a receiving plate 26, and a movable side mold plate 28 in this order toward the parting line PL. Also, spacer block
The ejector plate 32,
34 is provided, and the ejector plates 32 and 34 are provided with ejector pins 36 and return pins 38.
Note that reference numerals 40 and 42 respectively indicate an ejector plate guide pin and a guide pin bush.

Further, the movable side mold plate 28 is integrally assembled with four piece members 46 ... Having a cavity 44 and a piece mounting plate 48. As shown in FIG. 2, the piece member 46 is fitted and mounted in the mounting hole 48a formed in the piece mounting plate 48. The runner lock pin guide 16 for the runner stripper plate 8, the core mounting plate 20 for the fixed side mold plate 10, and the piece mounting plate 48 for the movable side mold plate 28 have stepped portions 8a and 16 respectively.
a, the stepped portions 10a and 20a, and the stepped portions 28a and 48b are in contact with each other to prevent the mold clamping force toward the parting line PL from engaging with each other, and reliably secure the respective parts made of different materials as described later. It is assembled. Similarly, in the core 18 for the core mounting plate 20 and the piece member 46 for the piece mounting plate 48, step portions 20b and 18a,
The step portions 48c and 46a are in contact with each other to form a retaining fit. Sign
Reference numeral 45 denotes an injection path from a sprue bush (not shown) in the mold 2 to the cavity 44 and its surroundings. The molding area 45 includes the locate ring 12,
Runner lock pin support plate 14, runner lock pin guide 1
6, a core 18, a core mounting plate 20, a runner plate 22, a cavity 44, a piece member 46, and a piece mounting plate 48.

In this example, the part of the molding main portion 45 excluding the runner lock pin support plate 14, the core mounting plate 20, and the piece mounting plate 48, the ejector pin 36, the return pin 38, the ejector plate guide pin 40, and the guide pin bush 42 are Each of them is made of carbon steel for machine structure such as S50C, and the runner lock pin support plate 14, the core mounting plate 20, the piece mounting plate 48, and the receiving plate 2 of the molding main portion 45 are formed.
6.Ejector plates 32 and 34 are made of aluminum, which is a lightweight metal material that is superior in heat resistance, pressure resistance, rigidity, etc., but superior in light weight and rust prevention compared to carbon steel for machine structure such as S50C. Has been done.

The fixed side mounting plate 4 is made of polyacetal, the movable side mounting plate 6 is made of bakelite, and the runner stripper plate 8, the fixed side template 10,
The spacer blocks 24, 24 and the movable side mold plate 28 are each formed of polybutylene terephthalate (PBT).

Since the receiving plate 26 is located in the space 30, the ejector plates 32, 34 have a rigidity sufficient to withstand the molding pressure.
Since they are thin-walled members, aluminum materials are used as lightweight metal materials.

The movable side mounting plate 6 may be formed of polyacetal similarly to the fixed side mounting plate 4, but bakelite having low thermal conductivity is used from the viewpoint of satisfying pressure resistance and reducing heat transfer to the molding machine. It was done. As a result, the heat transfer of the molding machine is blocked, and the instability of the temperature of the mold 2 is avoided.

In addition, the cooling water passage is usually a movable mold plate 10 and a movable mold plate.
The movable side mold plate 10, the movable side mold plate 28, the core mounting plate 20 and the piece mounting plate 48, which are provided in the 28 and 28, are in direct contact with the cooling water, all of which are made of an aluminum material or a synthetic resin material. And has a rust preventive function.
As a result, a rust preventive function can be obtained over the entire mold, and aesthetic deterioration due to rust does not occur.

As a result of the experiment, it was confirmed that a product comparable to the conventional mold in which all the constituent members such as the fixed-side mold plate 10 are made of steel can be obtained.

As described above, the injection path from the sprue bush to the cavity 44 and the forming main part 45 including the injection path and the periphery thereof are formed of metal such as steel, so that the forming accuracy is substantially ensured. Moreover, some of them (core mounting plate 20, piece mounting plate 48
Etc.) is made of aluminum to reduce the weight. Further, as in this example, in addition to the molding main portion 45, a portion where pressure resistance is particularly important compared to other constituent members (for example, a receiving plate).
26) and an ejector pin that requires heat resistance and wear resistance
If the sliding member such as 36 is made of a metal material, the reliability of ensuring the molding accuracy is further improved.

By using a synthetic resin, especially an engineering plastic such as polyacetal, for the portion excluding the molding main portion 45, the weight of the mold 2 can be greatly reduced without degrading the precision and quality of the molded product. According to the configuration of this example, the external dimensions described above are 200 mm × 230 mm × 260 mm, and the weight can be set to about 1/3 and about 25 kg.

Therefore, the small-sized one can be easily moved by inputting, and the large-sized one can suppress an increase in the size of the mechanical transfer means. Further, since it is possible to improve the smoothness in the replacement / attachment work to the molding machine and the handling in the distribution process, it is possible to reduce the work cost and the distribution cost.

Further, the constituent members such as the fixed-side mold plate 10 can be formed by injection molding, and it is expected that the manufacturing cost can be greatly reduced in the mold manufacturing.

In the above example, an example in which a specific synthetic resin is used for a specific constituent member has been shown, but the present invention is not limited to this, and various synthetic resins can be appropriately adopted within a range in which molding accuracy can be maintained. .

〔The invention's effect〕

According to this invention, in common with each claim, a portion requiring high heat resistance, pressure resistance, rigidity, etc. is formed of a steel material,
We used a lightweight metal material such as aluminum for the surrounding area, and a synthetic resin material for the outside to balance heat resistance, pressure resistance, rigidity, and weight reduction. In this case, there is an effect that the weight can be reduced without lowering the molding accuracy. Further, due to the effect of reducing the weight, there is an effect that the work of mounting on the molding machine, the exchange work and the transportation work are facilitated and the cost thereof is reduced.

Also, since the injection path is made of steel and a part of it is made of lightweight metal material such as aluminum and the rest is made of synthetic resin material, the weight is further reduced and the weight is reduced. Since the formed portion has a heat insulating function to stabilize the mold temperature, there is an effect that molding failure due to temperature instability can be prevented.

Further, in common with each claim, since the portion where the cooling water flows is formed of a lightweight metal material such as aluminum or a synthetic resin material having anti-corrosion properties, rusting due to cooling water is prevented and the appearance is reduced. It has the effect of avoiding and enabling long-term use.

Further, according to claim 2, since the member forming the cavity formed of the steel material and the cavity surrounding member formed of the light weight metal material such as aluminum have a fitting structure, it is easy to manufacture different materials. effective.

Further, according to claim 3, since the respective parts made of different materials are assembled by the stepped fitting structure, there is an effect that the assembling of the respective parts becomes reliable.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing an embodiment of an injection molding die according to the present invention, and FIG. 2 is an exploded perspective view of the cavity and its surroundings with some parts omitted. 44 …… Cavity, 45 …… Main part of molding

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kenji Guu 4-5-7 Tateishi, Katsushika-ku, Tokyo Inside Ciba Daishi Co., Ltd. (56) References JP-A-63-193809 (JP, A)

Claims (3)

(57) [Claims] 1. A member forming an injection path from a sprue bush to a cavity is formed of a steel material, and at least a cavity surrounding member that supports a member forming a cavity that is a part of the injection path is formed of a lightweight metal material such as aluminum. Then, an injection molding die in which a member constituting the injection path and a member other than the cavity surrounding member are formed of a synthetic resin material. 2. A mold for injection molding according to claim 1, wherein the member constituting the cavity is composed of a core and a piece member, and the cavity peripheral member is a piece to which the core mounting plate to which the core is fitted and the piece member to be fitted. An injection molding die consisting of a mounting plate. 3. The injection molding die according to claim 2, wherein the core is assembled to the core mounting plate and the core mounting plate is assembled to the stationary mold plate in a stepped fitting structure, and the piece member is assembled to the piece mounting plate. The piece mounting plate is an injection molding mold that is assembled to the movable side mold plate with a stepped fitting structure.