JPH11138608A - Injection mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize the uniform heating of molds up to a required temperature in a short period of time and, at the same time, the cooling of the mold in a short period of time by a method wherein planar heating members are respectively provided along the respective outer surfaces of a pair of inside molds and supporting molds are respectively arranged on the sides of the surfaces, which oppose to the respective inside molds, of these planar heating members. SOLUTION: This injection mold consists of respective pairs of inside molds 1 and 1 of planar heating members 2 and 2 and of supporting molds 3 and 3, each pair of which are assembled so as to be opposite to each other. Each of the inside molds 1 has an inner surface 1a, which marks out the required molding space S with the surface opposing to each other, and an outer surface 1b separated from the inner surface 1a by the predetermined distance. Each planar heating member 2 is formed in a three-dimensional shape so as to be arranged in contact with the outer surface 1b of the inside mold 1 opposing to the member 2. The supporting mold 3 is profiled so as to allow to install on an injection molder by contacting with the outer surface of the corresponding planar heating member 2 or the surface opposing to the outer surface 1b of the inside mold 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold for use in injection molding of plastic, metal, etc., and more particularly to a mold for rapidly heating and rapidly cooling the mold.

[0002]

2. Description of the Related Art In injection molding, by increasing the wall surface temperature of a mold, transferability on the surface of a molded product is improved.
It is known that there are various merits such as the occurrence of molding defects such as welds and sink marks can be prevented. However, in the conventional mold heating means, since the mold is heated by the heating element attached to the outer surface of the mold, it takes a very long time to uniformly heat the entire mold, It was necessary to always heat up even during holidays.

In general, if the temperature of the mold is raised, the time required to cool the mold and remove the molded product becomes longer, so that the molding cycle time becomes longer and the production efficiency decreases. Met.

[0004]

SUMMARY OF THE INVENTION According to the present invention, a mold is heated to a required temperature in a short time and uniformly, and the mold is cooled in a short time. An object of the present invention is to provide an injection molding die capable of preventing the occurrence of molding defects and preventing the occurrence of short molding defects by securing a good flow of molten metal, shortening the molding cycle time and increasing the production efficiency.

[0005]

SUMMARY OF THE INVENTION An injection mold according to the present invention comprises an inner surface formed so as to define a required molding space by surfaces facing each other, and an outer surface spaced from the inner surface by a predetermined distance. A pair of inner molds, a planar heating member provided along each outer surface of the inner mold, and a planar heating member disposed on a surface side of each of the planar heating members facing the inner mold. And a supporting mold.

When the sheet heating member is energized and generates heat, the heat from the sheet heating member heats the inner mold, and the wall surrounding the molding space in a much shorter time than when the entire mold is heated. Raise the temperature to the required temperature.

[0007] The injection mold according to the present invention can also be provided with a cooling passage for a cooling fluid to flow in the inner mold and / or the support mold. After the molding material has been injected into the molding space, a cooling fluid is caused to flow through the cooling passage, thereby rapidly reducing the mold temperature and shortening the molding cycle time. The cooling fluid in the cooling passage is usually withdrawn from the cooling passage when heating the mold again.

Further, in the injection mold according to the present invention, a heat insulating member can be provided between the sheet heating member and the supporting mold, whereby heat from the sheet heating member is transferred to the supporting mold. Prevents conduction to the mold, improves thermal efficiency for the inner mold, heats and cools the mold more quickly, and further reduces the molding cycle time.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 An injection molding die according to an embodiment of the present invention comprises:
As shown in FIG. 1, each pair of inner dies 1, 1, sheet-like heat generating members 2, 2 and support dies 3, 3 are combined to face each other.

Each inner mold 1 is formed of a conventional mold material, and is separated from the inner surface 1a by a predetermined distance from an inner surface 1a formed so as to define a required molding space S by surfaces facing each other. And an outer surface 1b. It is desirable that the distance between the inner surface 1a and the outer surface 1b, that is, the thickness, be as small as possible. However, an appropriate thickness should be selected according to the mold material to be used so that the pressure during injection molding does not cause distortion in the molding space S.

Each planar heating member 2 has a constant thickness and is formed in a three-dimensional shape so as to be arranged in contact with the outer surface 1b of the corresponding inner mold 1. The planar heating member 2 generates heat when energized, and generates a displacement in the positional relationship between the inner mold 1 and the support mold 3 due to the pressure during injection molding, thereby causing distortion in the molding space S. Any planar heating element can be used as long as it does not occur.For example, a material "MP" mainly composed of cement and a thermosetting resin manufactured and sold by Maeda Advanced Technology Research Institute Co., Ltd.
C (trade name) "can be used a heating element hardened by mixing a metal powder.

The support mold 3 is formed of a conventional mold material similarly to the inner mold 1, and is in contact with the outer surface of the corresponding planar heating member 2, that is, the surface facing the outer surface 1b of the inner mold 1. It is mounted so that it can be mounted on an injection molding machine. The support mold 3 and / or the inner mold 1 (the support mold 3 in the illustrated case) is provided with a cooling passage 4 through which a cooling fluid flows.

In the injection molding die of the present invention configured as described above, when power is supplied to the sheet heating member 2 from a power supply source (not shown), the sheet heating member 2 generates heat and the metal is heated. Heat the mold. At this time, since the distance between the inner surface 1a of the inner mold 1 and the planar heating member 2 is small, the temperature of the inner surface 1a of the inner mold 1 can be extremely quickly reduced as compared with the case where the entire mold is heated. It is possible to raise the temperature to a required temperature, and thereby, as described above, there is an advantage that the transferability onto the surface of the molded product is improved, and the occurrence of molding defects such as welds and sink marks can be prevented. be able to.

After the molding material is injected into the molding space S, the energization of the planar heating member 2 is stopped, and the cooling fluid is caused to flow through the cooling passage 4 to lower the mold temperature in a short time. Since the product can be taken out, the molding cycle time can be shortened, and the production efficiency can be improved. After cooling, the cooling fluid in the cooling passage 4 is withdrawn from the cooling passage 4 so as not to become an unnecessary heated object when the mold is heated again for the next molding operation.

[0015]

Embodiment 2 FIG. 2 is a view showing an injection molding die according to another embodiment of the present invention. A heat insulating member 5 is provided between a sheet heating member 2 and a supporting die 3. Except for this point, the configuration is the same as that of the above embodiment.

As the heat insulating member 5, any member can be used as long as it can prevent the heat from the planar heating member 2 from being conducted to the supporting mold 3. However, as in the case of the planar heating member 2, the positional relationship between the inner mold 1 and the support mold 3 is displaced by the pressure during the injection molding, and the molding space S is distorted. Should be selected. As an example of a material applicable to the heat insulating member 5, a material mainly composed of cement and a thermosetting resin (MP, which has been cited as an example of the basic material of the planar heating member 2).
C).

The cooling passage 4 in this embodiment has at least the inner mold 1 as shown in the figure because the heat-generating member 2 and the supporting mold 3 are thermally insulated by the heat insulating member 5. Only need to be provided. However, in order to prevent thermal energy from potentially being stored in the support mold 3 by the continuous molding operation and thereby prolonging the cooling operation time, the cooling passage 4 is also provided in the support mold 3. Is desirably provided.

The planar heating member 2 in this embodiment is prevented from conducting the heat from the planar heating member 2 to the supporting mold 3 and is conducted only to the inner mold 1, so that the heating time is shorter. The temperature of the inner surface 1a of the inner mold 1 can be raised to a required temperature and can be cooled in a shorter time, whereby the molding cycle time can be further shortened and the production efficiency can be increased. Will be easily understood.

[0019]

According to the present invention, the inner surface 1a of the inner mold 1 is provided.
When the space between the sheet heating member 2 and the sheet heating member 2 is small, when the sheet heating member 2 is heated to heat the mold, compared with the case where the entire mold is heated, the inner surface 1a of the inner mold is heated. The temperature can be raised to a required temperature in a very short time, thereby improving the transferability onto the surface of the molded product and preventing the occurrence of molding defects such as welds and sink marks. Benefits can be realized. Also, after the injection of the molding material, a cooling fluid is caused to flow through the cooling passage 4 to lower the mold temperature in a short time, and the molded product can be taken out.
The molding cycle time can be shortened, and the necessity of performing the necessary extra heat even during the conventional holidays is eliminated, thereby improving the production efficiency.

Further, by providing a heat insulating member 5 between the sheet heating member 2 and the supporting mold 3, the heat from the sheet heating member 2 is transmitted to the inner mold 1, while the heat is applied to the supporting mold 3. In order to prevent conduction, the mold can be raised to the required temperature in a shorter time and cooled in a shorter time, thereby further shortening the molding cycle time and improving the production efficiency. Can be increased.

[Brief description of the drawings]

FIG. 1 is a sectional view schematically showing an injection mold according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view schematically illustrating an injection mold according to another embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 inner mold 2 planar heating member 3 support mold 4 cooling passage 5 heat insulating member S molding space

Claims (3)

[Claims] 1. A pair of inner molds each having an inner surface formed so as to define a required molding space by surfaces facing each other and an outer surface separated from the inner surface by a predetermined distance, and Injection is characterized by comprising a planar heating member provided along each outer surface, and a supporting mold disposed on a surface of each of the planar heating members facing the inner mold. Mold for molding. 2. The injection mold according to claim 1, wherein a cooling passage for allowing a cooling fluid to flow is provided in the inner mold and / or the support mold. 3. The injection molding die according to claim 1, wherein a heat insulating member is provided between the planar heating member and the supporting die.