JPH09308954A - Mold cooling method - Google Patents

Abstract

(57) [PROBLEMS] To provide a method for cooling a mold, which is advantageous for enhancing the water permeability in the narrow cooling hole 25 and ensuring the cooling capacity of the mold 1. SOLUTION: A mold 1 having a fine cooling hole 25 having a small hole diameter.
This is a mold cooling method of cooling the mold 1 by passing cooling water through it. First, the thin cooling holes 25 are subjected to vacuum processing under reduced pressure. After that, the first valve 54 is opened to supply the water supply pump 53.
To pass water.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a mold cooling method. INDUSTRIAL APPLICABILITY The present invention can be used, for example, for cooling a cast pin.

[0002]

2. Description of the Related Art Japanese Utility Model Publication No. 61-162355 discloses that
Disclosed is a mold cooling technique in which a fine cooling hole forming a forward path and a fine cooling hole forming a return path are provided inside a pin-shaped metal pipe that is an element of the mold, and cooling water is passed through the fine cooling hole. Has been done.

[0003]

However, air is likely to accumulate in the thin cooling holes, which tends to become a resistance when passing water. In particular, the cooling water is vaporized by the heat of the mold and turned into high-pressure steam, which tends to cause resistance when passing water. Therefore, even if the supply pressure of the cooling water is increased, the water permeability to the small cooling holes is impaired. Therefore, there is a limit to the improvement of the mold cooling capacity.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a mold cooling method which is advantageous for enhancing the water permeability in the small cooling holes and ensuring the cooling capacity of the mold. To do.

[0005]

According to a first aspect of the present invention, there is provided a method for cooling a die, comprising cooling the die by passing cooling water through the die having a fine cooling hole. It is characterized in that water is passed after the cooling hole is subjected to a vacuum treatment under reduced pressure.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION According to the method of the present invention, thin cooling holes are subjected to vacuum treatment under reduced pressure. Therefore, the inside of the thin cooling hole is in a reduced pressure vacuum atmosphere, that is, a negative pressure state. After that, since the cooling water is passed through the narrow cooling holes, the resistance at the time of passing the water is reduced, and the water passing through the cooling holes is ensured.

The fine cooling holes can be formed inside the mold part which is apt to be overheated, for example inside the die-cast pin. The thin cooling holes may be straight cylindrical pores, but may be conical pores in some cases. The conical shape also includes a straight conical shape or a stepped conical shape. The average hole width (generally, the average diameter) of the thin cooling holes can be adopted depending on the type of mold. For example, 10 mm or less, 5 mm or less, 3 mm or less, 1 mm or less, and in some cases 0.5 mm or less can be adopted.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. A die-cast pin 1 as a protrusion is provided at a predetermined portion of the cavity die surface 10 of the die 1 for forming a cast product.
3 is integrally projected. A cooling hole 2 is formed inside the die portion near the root of the cast pin 13.
The cooling hole 2 has an inner surface 2w. The cooling hole 2 has a cylindrical shape, but is not limited to this.

A cooling pipe 3 is inserted into the cooling hole 2 substantially coaxially. Therefore, the outer diameter Dc of the outer surface 3w of the cooling pipe 3 is
It is set to be smaller than the inner diameter Db of the cooling hole 2 (Dc
<Db). The cooling pipe 3 is made of a metal pipe material such as a steel pipe, and includes a pipe line 30 and a discharge port 32 located at the tip of the pipe line 30. The discharge port 32 is configured by obliquely cutting the tip of the cooling pipe 3.

The cooling water supply system 5 includes a water supply tank 50, a forward path 51 connecting the water supply tank 50 and the cooling pipe 3, and a return path 52 connecting the outlet 2s of the cooling hole 2 and the water supply tank 50.
A water supply pump 53 provided on the outward path 51, an inlet-side electromagnetic first valve 54 provided on the outward path 51, and a return path 52.
And an electromagnetic second valve 55 on the outlet side provided in the.

The vacuum system 7 includes a vacuum passage 70 connected to the port of the second valve 55, a vacuum tank 72 provided in the vacuum passage 70, a vacuum pump 73 for maintaining the vacuum degree of the vacuum tank 72, and a vacuum passage 70. And a pressure sensor 74 provided in the. The controller 8 controls the water supply pump 53 via the signal line 53r and the first valve 54 via the signal line 54r.
Through the signal line 55r, the second valve 55, and the signal line 7
The vacuum tank 72 is controlled via 2r. Pressure sensor 7
The detection signal of No. 4 is input to the control device 8 (for example, a sequencer) via the signal line 74r.

The first valve 54 has a function of switching between communication and non-communication between the outward path 51 and the cooling pipe 3. The second valve 55 has a function of switching communication between the passage portion 52a and the passage portion 52b of the return passage 52 and communication between the passage portion 52a and the vacuum passage 70. Further, according to the present embodiment, the cooling hole 2 has a tip end portion with a thin cooling hole 25 having a substantially cylindrical shape and a bottom.
Are almost coaxially arranged. The rear end portion 25m of the narrow cooling hole 25 is close to the vicinity of the tip surface 13i in order to enhance the cooling performance of the casting pin 13 near the tip surface 13i. The hole diameter Da of the thin cooling hole 25 is set to be smaller than the outer diameter Dc of the cooling pipe 3 and the inner diameter of the conduit 30 of the cooling pipe 3. Of course, the hole diameter Da of the thin cooling hole 25 is smaller than the inner diameter Db of the cooling hole 2.

The inlet opening 25k of the thin cooling hole 25 is close to and faces the discharge port 32 of the cooling pipe 3. Therefore, it is advantageous to supply the cooling water from the discharge port 32 to the inner end portion 25m of the thin cooling hole 25. A mold temperature sensor 6 as a mold temperature detecting means for detecting the mold temperature of the casting pin 13 is provided near the casting pin 13 in the mold 1. As the mold temperature sensor 6, a thermocouple, a thermistor or the like can be adopted. The mold temperature signal detected by the mold temperature sensor 6 is input to the control device 8 via the signal line 6r.

In use, a molten metal having a high temperature is poured into the cavity 13 of the mold 1 while the mold 1 is clamped, and the molten metal is solidified to form a cast product. The molded casting product is released from the opened mold 1. As the molten metal, a light metal type such as an aluminum type can be generally adopted, but an iron type or the like can also be adopted in some cases. The mold temperature of the mold 1 gradually becomes higher as the number of molten metal injected increases. Especially, since the casting pin 13 for forming the casting hole is surrounded by the molten metal, the mold temperature of the casting pin 13 becomes high,
It is easily overheated. Therefore, the cooling water in the cooling holes 2 and the narrow cooling holes 25 is easily turned into high-pressure steam by heat and tends to remain in the cooling holes 2 and the small cooling holes 25 as an air pool.

Therefore, according to this embodiment, after the cast product is released from the mold, the next shot of molten metal is used in the cavity 1 of the mold 1.
Before being supplied to the nozzle 3, the vacuum tank 72 performs a reduced pressure vacuum process for sucking the cooling holes 2 and the narrow cooling holes 25 by the suction action. That is, the control device 8 switches the second valve 55 so that the passage portion 52a of the return passage 52 communicates with the vacuum passage 70, and the passage portion 52b of the return passage 52 does not communicate with the vacuum passage 70. Further, in the depressurization vacuum processing, the first valve 54 is closed and the outward path 51 and the cooling pipe 3 are not communicated. As a result, by the suction action of the vacuum tank 72, the cooling holes 2, the thin cooling holes 25, and further the inside of the cooling pipe 3 are sucked to be in a negative pressure state, and the air pool and residual cooling water remaining in these are sucked. To be removed. Foreign substances such as scales are also removed by suction.

When the reduced pressure vacuum treatment is completed as described above,
Next, water flow treatment is performed. That is, the control device 8 performs the switching operation of the second valve 55, and the passage portion 52 of the return path 52.
The passage portion 52a of the return passage 52 and the vacuum passage 70 are not communicated with each other while the passage a is communicated with the passage portion 52b. Furthermore the first
The valve 54 is opened, and the outward path 51 and the cooling pipe 3 communicate with each other. When the water supply pump 53 is turned on, the cooling water is passed through the cooling pipe 3, and thus the cooling hole 2. The cooling water that has reached the cooling holes 2 is also fed to the narrow cooling holes 25.
Therefore, the cast pin 13 is cooled from the inside. The rear end portion 25m of the thin cooling hole 25 has a tip surface 13i of the cast pin 13.
Since it is close to, it is advantageous to feed the cooling water also to the tip surface 13i side of the casting pin 13.

The cooling water supplied to the cooling holes 2 is returned to the return path 52.
It is returned to the water supply tank 50 through the passage portion 52a and the passage portion 52b. As described above, according to the present embodiment, the decompression vacuum process is performed before the water flow process for supplying the cooling water, so that the cooling holes 2, the narrow cooling holes 25, and the inside of the cooling pipe 3 are sucked and the The remaining air pool is easily removed. Therefore, the resistance at the time of water flow is reduced, the water flow of the cooling water is ensured, and the coolability of the mold 1 is ensured.

Further, when the fine cooling holes 25 are connected to the tip of the cooling holes 2 as in the present embodiment, it is difficult for the cooling water to pass through the fine cooling holes 25 in which air pools have occurred. However, according to this embodiment, the depressurized vacuum treatment is performed prior to the water passage treatment, so that the removability of the air pool accumulated in the narrow cooling hole 25 is improved. Therefore, even if the width of the narrow cooling hole 25 is small, the water permeability of the cooling water to the narrow cooling hole 25 is secured.

Further, according to the present embodiment, as can be understood from FIG. 1, since the inlet opening 25k of the narrow cooling hole 25 faces and faces the discharge port 32 of the cooling pipe 3, the discharge port 32 faces. It is advantageous to send the cooling water discharged from the inside of the narrow cooling hole 25. As described above, according to the present embodiment, it is possible to effectively cool the casting pin 13 that tends to become hot, especially the tip surface 13i side of the casting pin 13. Therefore, it is advantageous to reduce scoring defects and the like due to overheating of the casting pin 13, and can contribute to prolonging the life of the casting pin 13. Furthermore, since the solidification of the molten metal near the casting pin 13 can be promoted, the extension of the casting cycle time due to the unsolidified molten metal can be prevented.

Further, according to this embodiment, as can be understood from FIG. 1, the fine cooling hole 25 has a hole diameter smaller than the outer diameter of the cooling pipe 3. Therefore, it is advantageous to secure the die thickness M of the cast pin 13. Therefore, while securing the die thickness M of the casting pin 13,
The cooling performance by the cooling holes 2 can be secured. Since the die thickness M of the casting pin 13 can be secured in this manner, it is advantageous in preventing die cracking of the casting pin 13 and the durability of the casting pin 13 can be improved.

By the way, FIG. 2 shows the CP of the control device 8 described above.
The flowchart of the cooling process subroutine which U performs is shown. First, in step S102, preparation is completed, and it is determined whether or not the mold 1 is cooled. If NO, the process returns to the main routine. If YES, step S104
Then, the first valve 54 is closed to disconnect the outward path 51 and the cooling pipe 3 from each other. Further, the second valve 55 is switched to make the passage portion 52a of the return passage 52 communicate with the vacuum passage 70 and the passage portion 52b of the return passage 52 not communicate with the vacuum passage 70.

As a result, as described above, the vacuum tank 72
By the suction action of, the inside of the cooling hole 2, the narrow cooling hole 25, the inside of the cooling pipe 3 and the like are sucked and the vacuum processing is performed under reduced pressure. Therefore, the air holes and the like remaining in the cooling holes 2, the thin cooling holes 25 and the cooling pipes 3 are removed. In step S106, the pressure signal detected by the pressure sensor 74 is input. Step S
Proceeding to 108, it is determined whether the pressure signal is equal to or lower than the predetermined value, that is, it is determined whether the inside of the cooling hole 2 is depressurized to the predetermined value. Y
ES, that is, if the pressure is reduced to a predetermined value or less, the cooling pipe 3
It is highly probable that the air pool etc. that had remained in Therefore, from step S108 to step S110
Then, the first valve 54 is opened, the outward path 51 and the cooling pipe 3 are communicated with each other, and the water supply pump 53 is turned on.

Further, in step S110, the second valve 5
5 is switched to connect the passage portion 52a and the passage portion 52b of the return passage 52 and the passage portion 52b of the return passage 52.
And the vacuum path 70 are not communicated. As a result, the water flow processing is executed as described above. The mold temperature signal of the mold temperature sensor 6 is input in step S112, and it is determined in step S114 whether the temperature detected by the mold temperature sensor 6 has dropped and reached a predetermined temperature. The water flow treatment is continued until the temperature reaches the predetermined temperature. If the result of the determination in step S114 is YES, that is, if the temperature of the mold 1 has dropped to a predetermined temperature, step S114
The routine proceeds to 116, where the water supply pump 53 is turned off, the first valve 54 is closed, the water passage processing is completed, the casting OK signal is output, and the routine returns to the main routine. As a result, the casting process of the mold 1 into the cavity 13 is started.

As a result of the determination in step S108, NO,
That is, when the inside of the cooling hole 2 is not depressurized to a predetermined value, the process proceeds from step S108 to step S120, and the timer for measuring the suction time is started. Until the timer for measuring the suction time expires, the process returns to step S106 via step S122. Here, the expiration of the timer for measuring the suction time means that the inside of the cooling hole 2 is not sufficiently decompressed even if the suction process is continued until the timer expires. In this case, it is estimated that there is a vacuum leak in the water passage and the degree of pressure reduction is not improved by the outside air entering from the vacuum leak portion. Therefore, step S12
From 2 to step S124, an alarm signal is output to the alarm device 88 to warn that there is a leak in the water passage, and the process returns to the main routine. Examples of the alarm device 88 include a buzzer and an indicator light.

(Other Example) When starting the water flow processing after the reduced pressure vacuum processing, the operation timing of the second valve 55 may be delayed relative to the opening timing of the first valve 54. That is, when the water flow processing is started after the depressurization vacuum processing for depressurizing the cooling holes 2 and the narrow cooling holes 25 is completed, the first valve 54 is opened to open the cooling pipe 3 and the cooling holes 2.
Immediately after starting the passage of water into the inside, after delaying the ΔTc time (depending on the mold 1, for example, 0.5 seconds to several seconds), the second valve 55 is operated to operate the passage portion 52a of the return passage 52 and the passage portion. You may connect with 52b.

In other words, during the above ΔTc time,
The second valve 55 keeps the passage portion 52a from not communicating with the vacuum passage 70, and keeps the passage portion 52b from not communicating with the passage portion 52a. Therefore, the communication between the passage portion 52a and the passage portion 52b of the return path 52 is delayed by ΔTc time immediately after the start of water passage. Therefore, it is advantageous to prevent the outside air from entering the cooling hole 2 or the narrow cooling hole 25 from the return path 52. Therefore, the reduced pressure vacuum degree of the cooling holes 2 and the thin cooling holes 25 is easily maintained at a high level during the above-described ΔTc. Therefore, it is advantageous to allow the cooling water from the outward path 51 to enter the cooling holes 2 and further the depths of the narrow cooling holes 25.

In the above-mentioned example, the cooling holes 2 are provided in the thin cooling holes 25.
Are connected coaxially, but may be connected non-coaxially. In the above example, the hole diameter Da of the thin cooling hole 25 is
Is larger than the outer diameter Dc of the cooling pipe 3 and is smaller than the diameter 30 of the cooling pipe 3.
It is set smaller than the inner diameter of, but not limited to this,
The hole diameter Da of the narrow cooling hole 25 is smaller than the outer diameter Dc of the cooling pipe 3, but may be larger than the inner diameter of the conduit 30.

Alternatively, the example shown in FIGS. 3 and 4 may be adopted. According to the example shown in FIG. 3, the multi-stage fine cooling holes 25 having a multi-stage small size are connected to the cooling holes 2.
Further, according to the example shown in FIG. 4, the thin cooling holes 25 having a conical surface structure in which the hole diameter is tapered and continuously decreases are connected to the cooling holes 2. According to the examples shown in FIGS. 3 and 4, the hole diameter of the inlet opening 25k of the thin cooling hole 25 is indicated by Da, and the hole diameter of the deep end portion 25m of the thin cooling hole 25 is indicated by D _ao . In these examples, the relationship of D _b > D _a > D _C > D _ao is shown in the drawings. However, not limited to this, the relationship of D _a <D _C may be used.

(Supplementary Note) The following technical idea can be understood from the above-described embodiments. The method according to claim 1, wherein the fine cooling hole has a bottomed shape with a tip not penetrated. A first valve that opens and closes the inlet side of the thin cooling hole and a second valve that opens and closes the outlet side of the thin cooling hole are provided, and during the water flow treatment, the second valve is opened more than the opening timing of the first valve. 2. The method according to claim 1, wherein the opening timing is delayed by a predetermined time.

[0030]

According to the method of the present invention, the thin cooling holes of the die are vacuum-treated under reduced pressure. Therefore, the resistance during water flow is reduced. After that, the cooling water is passed through the narrow cooling holes, so that the air pool that becomes a resistance at the time of passing the water is removed and the water passage is secured. Therefore, the cooling effect of the mold is secured.

[Brief description of drawings]

FIG. 1 is a block diagram of a cooling technique.

FIG. 2 is a flowchart of a cooling process subroutine executed by a control device.

FIG. 3 is a configuration diagram of a cooling technique according to another embodiment.

FIG. 4 is a configuration diagram of a cooling technique according to another embodiment.

[Explanation of symbols]

In the figure, 1 is a mold, 13 is a casting pin, 2 is a cooling hole, 25
Indicates a thin cooling hole, 25m indicates a rear end portion, 3 indicates a cooling pipe, and 8 indicates a control device.

Claims (1)

[Claims] 1. A method of cooling a mold, comprising cooling a mold by passing cooling water through a mold having fine cooling holes, wherein the fine cooling holes are subjected to a vacuum treatment under reduced pressure, and then water is passed through. Mold cooling method.