JP2000015421A - Device for cooling metallic mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooling device for metallic mold, in which the local cooling can be limited to the desired range and also, the cooling timing can arbitrarily be set in accordance with each process at the time of forming. SOLUTION: A pressure reducing chamber 14 is arranged at the back of a runner part 22 in a cavity and in the pressure reducing chamber 14, a nozzle 10 for atomizing cooling water, is disposed. Then, after filling molten material into the cavity, the cooling water from the nozzle 10 is ejected to the target 24 at the tip surface in the pressure reducing chamber 14 through a control valve 5, piping 4, cooling water supplying way 3 and nozzle supporting pipe 9. The other surface in the pressure reducing chamber 14 is covered with the heat insulating material 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold cooling device used for a plastic molding die, a metal casting die and the like.

[0002]

2. Description of the Related Art Molding using a molding die such as plastic molding or metal casting generally controls the temperature of the mold by passing water through a cooling water pipe. In addition, there is a demand for thinner molded products and improved surface finish quality. Due to these requirements, the mold temperature during molding tends to be high in order to ensure the fluidity of the molten material, and the time required for cooling and solidifying the molten material is prolonged, thereby deteriorating productivity. was there.

[0003] In particular, the runner portion, which is a product portion and a non-product portion, has different wall thicknesses, and generally requires a longer cooling time because the runner portion is thicker. As described above, the cooling time is longer in the non-product part, and the productivity is deteriorated. Therefore, the productivity is improved by cooling a local part such as a runner part.

For example, Japanese Patent Application Laid-Open No. Hei 9-136325 proposes a mold apparatus for controlling the supply of cooling water and steam by switching. Further, Japanese Patent Application Laid-Open No. Hei 6-315751 proposes a mold cooling device for locally cooling a mold.

FIG. 3 shows a mold apparatus described in Japanese Patent Application Laid-Open No. Hei 9-136325. A chamber 43 is provided on the back side of the cavity surface 42 of the mold main body 41.
Is connected to a water supply pump 45 and a boiler 46 so as to be switchable, and the chamber 43 is connected to a vacuum pump 49 by a pipe 48. When the mold body 41 is cooled, cooling water is injected into the chamber 43 and the inside of the chamber 43 is reduced to a predetermined pressure by the vacuum pump 49. Further, steam is supplied from the boiler 46 to heat the mold body 41.

FIG. 4 is a view showing a mold cooling device described in Japanese Patent Application Laid-Open No. 6-315751. A cooling hole 62 is formed at a desired position of the mold member 61, and a cooling pipe 63 is inserted into the hole 62. The cooling pipe 63 has a bottomed cylindrical shape, and has a plurality of nozzle holes 63a arranged in the axial direction. The inside of the cooling pipe 63 is an outward passage 62 of the cooling water.
a, and a return path 62b of the cooling water is formed between the cooling pipe 63 and the hole 62. Reference numeral 68 denotes a forward pipe, reference numeral 69 denotes a return pipe, and reference numeral 67 denotes a holder for disposing the cooling pipe 63 and the like.

[0007]

However, in the prior art described in these publications, the boundary between the range to be heated and the range to be cooled is not clear, and the boundary between the non-heated portion and the portion to be cooled is not clear. There is no configuration to make.

For this reason, the heat capacity of the portion to be heated and cooled becomes large, and switching between heating and cooling in a short time such as injection molding is delayed.

As a result, undesired portions are also heated or cooled at the same time, thereby deteriorating the quality of the obtained product and causing a time lag until the cooling effect at the desired cooling location is exhibited. There is a disadvantage that the improvement is not sufficient.

Further, there is a problem that the quality of a molded product is deteriorated because a large temperature change occurs even in a product portion near a local desired cooling range such as a runner portion.

The present invention has been made in view of such a problem, and it is possible to limit the local cooling to a desired range, and to arbitrarily set a cooling timing in accordance with each process at the time of molding. It is an object to provide a simple mold cooling device.

[0012]

A mold cooling device according to the present invention is a mold cooling device for injecting a melt into a cavity formed in a mating surface of a pair of molds and solidifying the melt.
A decompression chamber provided behind the cavity surface of the first mold, a suction passage communicating with the decompression chamber and connected to an external exhaust unit, a nozzle disposed in the cavity, And a coolant supply path connected to the nozzle for supplying a coolant from an external coolant supply means to the nozzle, wherein the nozzle injects the coolant toward a surface of the decompression chamber on the cavity surface side. .

In this mold cooling device, it is preferable that at least a part of the surface of the decompression chamber other than the surface on which the refrigerant is injected from the nozzle is covered with a heat insulating material.

In the present invention, since the refrigerant is injected from the nozzle into the vicinity of the cavity surface of the mold in the decompression chamber, only the refrigerant injection surface can be locally cooled, and the temperature in the surrounding area can be reduced. Can be suppressed. Thereby, it is possible to improve the molding quality and the productivity.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below with reference to the accompanying drawings. FIG. 1 is a mold cross-sectional view illustrating a mold cooling device according to an embodiment of the present invention.

The mold according to the present embodiment includes a movable mold 1 and a fixed mold 2. The movable mold 1 is divided into a divided mold 1a and a divided mold 1b. In mold 1 and mold 2,
A cooling water pipe 12 is provided for controlling the temperature of each mold, and a cavity is formed between the molds 1 and 2 by overlapping the molds 1 and 2. The cavity includes a product part 23, a runner part 22, and a gate therebetween. The fixed mold 2 is provided with a sprue 21 for supplying a melt to the runner portion 22.

On the other hand, the movable mold 1 is provided with a decompression chamber 14 in a closed space behind the runner 22, and a suction path 8 communicating with the decompression chamber 14 is formed in the mold 1. . The suction passage 8 communicates with an external pipe 7, which is connected to a vacuum pump 6.

In the decompression chamber 14, the spray target 2, which is the surface behind the runner 22 in the decompression chamber 14, is provided.
4 is provided with a spray nozzle 10 for spraying cooling water. The nozzle 10 communicates with and is supported by a nozzle support tube 9. The nozzle support tube 9 communicates with a cooling water supply passage 3 provided in the mold 1, and the cooling water supply passage 3 is connected to an external piping. 4 is connected to a cooling water supply source. The pipe 4 is provided with a valve 5, and by adjusting the valve 5, the amount of cooling water jetted from the nozzle 5 can be adjusted.

On the inner surface of the decompression chamber of the split mold 1b, a tubular heat insulating material 11 for covering the side surface of the decompression chamber is provided. The heat insulating material 11 prevents the cooling effect from reaching the surroundings and reduces the apparent heat capacity of the portion to be cooled, thereby improving the responsiveness during the operation of the cooling device. Further, an O-ring 13 for airtightly shielding the decompression chamber 14 is provided on the mating surface of the split mold 1a and the split mold 1b. Split mold 1a and split mold 1
b, the heat insulating material 11 etc.
Can be placed or removed.

Next, the operation of the mold cooling device configured as described above will be described. First, the operation in the case of plastic injection molding will be described. The molding step is roughly divided into four steps: a material melting step, an injection filling step, a cooling step, and a product removal step. To describe the injection filling step in more detail, it is to inject a molten material into a gap in a mold. The molten material starts filling from a sprue 21 and reaches a product part 23 via a runner part 22. , Until the material fills up to the end of the cavity. At this time, during the filling step, it is desirable that the temperature of the flow path be higher in order to ensure the fluidity of the molten material. A higher mold temperature is also advantageous for improving the quality of the product, such as the transferability of the mold surface in the product part 23. However, in the cooling step after filling is completed, it is natural that the lower the mold temperature is, the longer the time until cooling and solidification, that is,
Since the time required to be able to take out is shortened, productivity is increased. In addition, in most cases, the runner portion is thicker than the product and is hard to be cooled. Therefore, the cooling time greatly depends on the cooling of the runner portion. Therefore, during the flow of the molten material, the temperature of the entire mold is adjusted by flowing cooling water through the cooling pipe 12, and the spray of the cooling water into the decompression chamber 14 is stopped while the control valve 5 is closed. .

When the filling of the molten material is completed, the control valve 5 is opened and the spray target 24 in the decompression chamber 14 is opened.
Spray cooling water. Since the inside of the decompression chamber 14 is maintained in a decompression environment by the vacuum pump 6, the spray target 24
The cooling water adhering to the gas evaporates and exhibits an efficient cooling effect. Since the portions other than the spray target 24 are blocked by the heat insulating material 11, the spreading of the cooling effect to the surrounding unnecessary portions is prevented. The molten material filled in the product forming section 23 is deprived of heat by the molds 1 and 2 and solidified by cooling. Cooling of the entire mold is performed by flowing a heat medium such as cooling water through the cooling water pipe 12.

After the predetermined cooling step is completed, the molds 1 and 2
Open and remove the solidified product. At this stage, the control valve 5 is closed, the spray of the cooling water is stopped, and the vaporized vapor in the decompression chamber 14 is discharged to the outside by the vacuum pump 6 and the pressure in the decompression chamber 14 in the next cycle is reduced. I do.

Thereafter, the molds 1 and 2 are closed, and the process proceeds to a molten material filling step, and these steps are repeated.

In this embodiment, during the flow of the molten material,
With the cooling device stopped, the mold temperature is controlled by the cooling water pipe 12, and after the material is charged, the cooling device is operated so as not to affect the product forming portion 23, and the runner portion 22 is limited to rapidly cool the product. Productivity can be improved without causing a decrease. FIG. 2 shows a mold cooling device according to another embodiment of the present invention. This embodiment has the same basic configuration as the embodiment shown in FIG. 1, and the same components are denoted by the same reference numerals and detailed description thereof will be omitted. In the present embodiment, the control method of the cooling water spray timing is improved. FIG. 2 shows the mold cooling device. As shown in FIG. 2, in the present embodiment, a temperature sensor 31 is attached to the spray target 24 in the decompression chamber 14.

With this arrangement, when the temperature of the spray target 24, that is, the portion requiring local cooling becomes higher than a certain temperature, the control valve 5 is opened to cool the corresponding portion. Is stopped, the corresponding portion can be controlled at a constant temperature.

[0026]

As described above, according to the present invention,
During the flow of the molten material, unnecessary cooling of the mold temperature is not performed, and a cooling effect can be imparted only to a portion, such as a runner portion, which needs to be rapidly cooled after completion of filling.

Further, in the present invention, the amount of the refrigerant for the local cooling can be adjusted at an arbitrary timing by the control valve, and the adjustment of the cooling timing and the degree of the adjustment are easy.

Further, by providing a heat insulating material in the decompression chamber, the cooling range is limited to the spray target, and the heat capacity of the portion to be cooled is reduced. Therefore, rapid cooling becomes possible. Return to temperature is quicker.

Further, by limiting the cooling range, it is possible to improve the productivity by separating a part such as a product where the mold temperature has a great influence on the quality.

Therefore, by using the mold cooling device of the present invention, it is possible to shorten the cooling time while increasing the mold temperature to improve the product quality, and to improve the productivity. it can.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a mold cooling device according to an embodiment of the present invention.

FIG. 2 is a partially enlarged sectional view showing a second embodiment of the present invention.

FIG. 3 is a view showing a conventional mold cooling device.

FIG. 4 is a view showing another conventional mold cooling device.

[Explanation of symbols]

 1: movable side mold 2: fixed side mold 3: cooling water supply path 4: piping 5: control valve 6: vacuum pump 7: piping 8: suction path 9: spray nozzle support pipe 10: spray nozzle 11: heat insulating material 12: cooling water pipe 13: O-ring 14: decompression chamber 21: sprue 22: runner section 23: product forming section 24: spray target

Claims (6)

[Claims] In a mold cooling device for injecting and solidifying a melt into a cavity formed on a mating surface of a pair of molds, a decompression provided behind a cavity surface of one of the first molds. Chamber, a suction passage communicating with the decompression chamber and connected to an external exhaust unit, a nozzle disposed in the cavity, and supplying a refrigerant from an external refrigerant supply unit connected to the nozzle to the nozzle. A cooling medium supply path, and the nozzle injects the refrigerant toward the surface of the decompression chamber on the cavity surface side. 2. The mold cooling device according to claim 1, wherein at least a part of a surface of the decompression chamber other than a surface from which the refrigerant is injected from the nozzle is covered with a heat insulating material. 3. The mold cooling device according to claim 1, wherein a surface of the decompression chamber from which the refrigerant is injected from the nozzle is located at a position behind a runner portion in the cavity. 4. A sprue for injecting a melt into the runner portion is provided in a second mold paired with the first mold in which the decompression chamber is provided. The mold cooling device according to any one of claims 1 to 3. 5. The mold cooling device according to claim 1, wherein the runner portion in the cavity communicates with a product portion into which a product is cast. 6. The first mold in which the decompression chamber is provided is a divided mold in which the decompression chamber is divided into two, and the first mold is assembled by combining these divided molds. The mold cooling device according to any one of claims 1 to 5, wherein: