JP2001314952A - Cooling method for mold for die casting and its apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooling method of a mold for die casting capable of cooling efficiently the mold for die casting by effectively using latent heat, and decreasing quantity of supply water and waste water and its apparatus. SOLUTION: The cooling method for the mold for die casting sprays mist having more than and equal to 250 μm to less than and equal to 700 μm of a particle size onto the surface of the mold. The cooling apparatus for the mold for die casting is arranged with a nozzle 13 producing mist having more than and equal to 250 μm to less than and equal to 700 μm of a particle size toward the surface of the mold.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for cooling a die-casting die for cooling a die after die-casting to a predetermined temperature.

[0002]

2. Description of the Related Art Since a die for die casting is formed by injecting a molten metal such as aluminum under pressure, after forming, the inner surface temperature of the die is raised to 270 ° C. or more by the molten metal. The mold temperature raised by injection molding had to be cooled to around 200 ° C. before the next molding. This is because when the aluminum is injected into the die casting mold, if the temperature of the die casting mold is too low, the molten metal begins to harden quickly as the molten metal flows into the mold, And the molding was poor. Further, if the temperature of the die casting mold is too high, it takes a long time to cure the molten metal flowing into the mold, so that the time until the completion of the molding is prolonged, resulting in a problem that the productivity is reduced. For this reason, cooling water has been sprayed on the inner surface of the die casting mold to cool the die casting mold. However, the amount of water sprayed at this time, the die casting die
If it is not possible to cool to about 00 ° C., it has been a general method to increase the amount of cooling water using a nozzle having a large nozzle diameter to lower the temperature. However, when the nozzle diameter of the nozzle is increased, the spray angle tends to be reduced, so that the nozzles must be arranged more densely and a large amount of water is consumed. In addition, there is a problem that even if a large amount of water is consumed, cooling is not effectively performed due to film boiling. Further, by spraying a large amount of water, water that did not evaporate easily remained in the depression of the die casting die. If molten metal is injected while leaving water in the cavity of the die casting mold, a phenomenon such as steam explosion occurs, which is dangerous and causes molding defects. The water remaining in the mold must be blown off by air blow, but there is also a problem that it takes a long time to dry due to a large amount of remaining water, thus lowering productivity and increasing costs.

[0003]

SUMMARY OF THE INVENTION The present invention relates to a die casting mold capable of efficiently cooling a die casting mold by effectively utilizing latent heat, reducing the amount of water used, and reducing the amount of waste water. It is an object of the present invention to provide a cooling method and a cooling device.

[0004]

In order to achieve the above object, the present invention provides a method for cooling a die casting die which sprays a mist having a particle diameter of 250 μm to 700 μm on the die surface. In the invention of claim 1, a method of cooling a die casting mold in which the mist spray region is overlapped so that the particle distribution is uniform is defined as the invention of claim 2, and the method for cooling the die having a particle diameter of 250 μm or more and 700 μm or less. A cooling device for a die-casting die, in which a nozzle for generating mist is provided facing the die surface, is defined as the invention of claim 3. In the invention of claim 3, the periphery of the mist spraying region is made uniform in particle distribution. The cooling device for the die casting die in which the nozzles are juxtaposed so as to overlap each other is defined as the invention of claim 4, and in the invention of claim 4, the nozzle has a diameter of 50 to 70 mm.
The cooling device for the die-casting dies, which are arranged in parallel at the intervals described above, is the invention of claim 5.

[0005]

Next, a preferred embodiment of the present invention will be described in detail with reference to FIGS. Reference numeral 1 denotes a die-casting apparatus, the die-casting apparatus 1 includes a fixed platen 3 for mounting a die-casting die erected on a base 2,
A movable platen 4 for attaching a die for die casting, which is slidably guided by a tie bar 6 described later, and a fixed platen 3
A tie bar 6 stretched between the link housing 5 and a mold clamping cylinder 7 attached to the link housing 5;
It comprises an injection cylinder 8, a plunger rod 9, and a spray unit 10 for cooling a die casting die. 11 is a male type attached to the movable platen 4, 1
Reference numeral 2 denotes a female die attached to the fixed platen 3.

The spray unit 10 is disposed between the opened male mold 11 and the female mold 12 so as to be able to protrude and retract. A large number of nozzles 13 are attached to the front and rear surfaces of the spray unit 10. ing. The nozzle 13 has a particle diameter of 250 μm or more and 700 μm or less, preferably a particle diameter of 3 μm.
It generates water having a particle size of 500 µm, most preferably within a range of 50 µm to 600 µm. This value is shown in FIG.
Are based on the knowledge obtained from the graph of the experimental results shown in FIG. The nozzle 13 generates a mist having a particle diameter of 250 μm with a nozzle diameter of 0.4 mm, a mist having a particle diameter of 380 μm with a nozzle diameter of 0.7 mm, and a mist having a particle diameter of 500 μm with a nozzle diameter of 1 mm. 3mm
Generates a mist with a particle diameter of 630 μm, and a nozzle diameter of 1.6.
A mist having a particle diameter of 700 μm in mm is sprayed. In the graph, 1 second equivalent, 2 seconds equivalent, 3 seconds equivalent, and 4 seconds equivalent indicate the amount of water when a conventional mist having a nozzle diameter of 5 mm and a particle diameter of 1500 μm is sprayed for 1, 2, 3, 4 seconds. .
The particle size of the cooling water sprayed from the nozzle 13 is 700 μm
The following is the fact that the latent heat of water could be used to the maximum by inferring from the numerical values obtained in the experiment. Because it is a target. This is because when the particle size is large, for example, when water is applied to a high-temperature iron plate, a phenomenon occurs in which the water rolls around on the iron plate and hardly evaporates. This phenomenon is called film boiling, and a film of boiling steam is formed between the iron plate and the polka dots, and the steam is slowly dissipated. And the cooling effect is reduced.

However, when water is made into small water droplets and dropped on an iron plate, the water droplets touching the iron plate evaporate instantaneously. Even if the water droplets do not evaporate instantaneously, the vapor that comes into contact with the iron plate and evaporates due to the small size of the water droplets is dissipated from its surroundings, and the water droplets do not float due to the vapor pressure. It is transmitted and evaporates rapidly. Then, the iron plate can be rapidly cooled by the heat of vaporization caused by the evaporation of the water droplets. For this reason, the smaller the particle size of the mist to be sprayed, the better. And the particle diameter is 250 μm or more.

The nozzles 13 are arranged in the spray unit 10 at intervals of 50 to 70 mm.
The most preferred spacing is 60 mm. This is based on the graphs of FIGS. 3, 4, and 5 obtained by conducting experiments. As shown in these graphs, the nozzle diameter was 1 mm
40 mm, 60 mm, 80 mm, 1 nozzle
50mm, 100mm, 1
When sprayed at a spray distance of 25 mm, a thermocouple meter point 1ch provided at the center point on the vertical center line of the test body, and thermocouple meter points 3ch and 7 arranged at equal intervals below the thermocouple meter point
ch and thermocouple meter point 5 located above the center point
This is because, as a result of measuring the temperature in the channel, it was found that when the nozzles were arranged at a nozzle interval of 60 mm regardless of the spray distance, the temperature decreased most efficiently and the cooling effect was high.

In the above-described apparatus, the movable platen 4 guided by the tie bar 6 is slid toward the fixed platen 3 by operating the mold clamping cylinder 7. Then, the male mold 11 of the movable platen 4 is matched with the female mold 12 of the fixed platen 3 and the mold is clamped. Before the mold clamping, the male mold 11 and the female mold 12 are cooled by the mist sprayed by the nozzle 13 of the spray unit 10 and are cooled by 200 m.
The temperature has dropped to around ℃. Next, the injection cylinder 8 is operated to inject molten metal into the closed male mold 11 and female mold 12 by the plunger rod 9. The injected molten metal is cooled and hardened by the cooling water circulating in the male mold 11 and the female mold 12.

When the molding is completed in this way, the mold clamping cylinder 7 is operated in reverse to retract the movable platen 4 guided by the tie bar 6, and the male mold 11 of the movable platen 4 and the female mold 12 of the fixed platen 3 Open the mold. After the mold is opened, the die-cast molded product is released from the die-casting mold. After releasing, the spray unit 10 is moved between the male mold 11 and the female mold 12 which are opened. Then, by spraying mist from a number of nozzles 13 attached to the front and rear surfaces of the spray unit 10 at intervals of 60 mm,
A mist having a particle diameter of 500 μm is sprayed on the inner surfaces of the molds of the male mold 11 and the female mold 12, and the mist evaporates instantly without causing film boiling. And the die for die-casting is rapidly and effectively cooled by the heat of vaporization at the time of evaporation. In addition, since mist with a small particle size is sprayed, the water that has touched the die-casting mold evaporates reliably, and unevaporated water droplets hardly remain in the dents of the die-casting mold. Since the air blow processing for blowing off the water droplets remaining in the depression of the mold can be reduced, the productivity can be increased and the cost can be reduced.

In the preferred embodiment, the mist that can cool the mold most efficiently has a particle diameter of 500 μm.
However, it goes without saying that a mist having a particle diameter of 250 μm to 700 μm that can be cooled most efficiently according to the shape of the mold, the size of the mold, and the like may be selected and sprayed. In the preferred embodiment, the nozzles 13 are arranged at intervals of 60 mm.
Needless to say, the nozzles 13 may be arranged at intervals of 50 mm to 70 mm at which cooling can be performed most efficiently according to the shape of the mold, the size of the mold, and the like.

[0012]

As is apparent from the above description, the present invention sprays a mist having a particle size of 250 μm or more and 700 μm or less on the die surface of the die casting die, so that the mist evaporates on the die surface without causing film boiling. As a result, the mold surface is effectively cooled by the heat of vaporization accompanying the evaporation, and the water consumption can be reduced to a fraction of that in the conventional case. In addition, the reduction of water consumption reduces the amount of wastewater, so that environmental pollution due to wastewater can be reduced. Furthermore, the amount of water remaining on the mold and the amount of moisture adhering to the surface of the mold are small, so that the time for drying the mold and the time for air blowing can be reduced. In addition, by reducing the amount of water to be sprayed, the adhesion of the release agent is also improved, and the amount of the release agent used can be reduced.In addition, since the release is reliably performed, the product yield is improved, In addition, the mold lasts well and can be used for a long time. In addition, as described in claim 4, by arranging the nozzles side by side so that the peripheral edges of the mist spray region overlap so that the particle distribution is uniform, there are various advantages such as uniform cooling of the mold surface. Things. Therefore, the present invention greatly contributes to the development of the industry as a method and an apparatus for cooling a die casting die which has solved the conventional problems.

[Brief description of the drawings]

FIG. 1 is a side view showing a preferred embodiment of the present invention.

FIG. 2 is a side view showing a spray state of a preferred embodiment of the present invention.

FIG. 3 is a graph showing a drop temperature at each nozzle interval when a spray distance is 50 mm.

FIG. 4 is a graph showing the falling temperature at each nozzle interval when the spray distance is 100 mm.

FIG. 5 is a graph showing the falling temperature at each nozzle interval when the spray distance is 125 mm.

FIG. 6 is a graph showing a time required to reach a certain temperature when a mist of each particle diameter is sprayed.

[Explanation of symbols]

 13 nozzles

Claims (5)

[Claims] 1. A method for cooling a die-casting die, comprising spraying a mist having a particle diameter of 250 μm or more and 700 μm or less onto the die surface. 2. The method for cooling a die casting die according to claim 1, wherein the peripheral edges of the mist spray region are overlapped so that the particle distribution is uniform. 3. A cooling device for a die casting die, wherein a nozzle for generating a mist having a particle diameter of 250 μm or more and 700 μm or less is provided facing the die surface. 4. The nozzles are juxtaposed so that the peripheral edges of the mist spray region overlap so that the particle distribution becomes uniform.
4. The cooling device for a die casting die according to 4. 5. The cooling device for a die casting die according to claim 4, wherein the nozzles are juxtaposed at intervals of 50 to 70 mm.