JPH1190613A - Low pressure casting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a shrinkage cavity from being generated caused by an insufficient pressurized time near to a gate or the collapse of directive solidification. SOLUTION: In the relation between a core print temp. detected with a temp. sensor 35 and a molten metal temp. detected with a temp. sensor 36, in the case that the both of the core print temp. and the molten metal temp. are higher than a threshold temp, the water is passed for the longest time into a first coolant passage 20 to cool it, in the case that the molten metal temp. is lower than the threshold value, the water passing time into the first coolant passage 20 is shortened as the core print temp. is lower and the cooling speed of the molten metal is partially controlled according to the position of the die through a controller 40.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low-pressure casting apparatus for filling a molten metal into a mold by pressurizing the surface of a molten metal when, for example, casting a cylinder head of an automobile engine.

[0002]

2. Description of the Related Art A conventional low pressure casting apparatus is disclosed in
No. 148449 discloses that after a molten metal is charged into a mold under pressure, the temperature of the mold is detected, and the amount of cooling water is controlled based on the difference between the mold temperature and the reference temperature, thereby reducing the cooling time. A low-pressure casting method that suppresses variation is disclosed.

[0003]

However, the conventional low-pressure casting method does not consider the variation in the temperature of the molten metal, and therefore has the following problems. That is, when the temperature of the molten metal is higher than the set temperature due to the variation of the temperature of the molten metal, it takes time until the temperature of the molten metal reaches the set temperature range, so that the cycle time of casting becomes longer.

If the temperature of the molten metal is higher than the set temperature, shrinkage cavities are likely to occur near the gate due to insufficient pressurization time.

If the temperature of the molten metal is lower than the set temperature, the directional solidification of the molten metal (the characteristic of solidifying from the inside of the cavity) is broken and shrinkage cavities are likely to be generated near the gate.

SUMMARY OF THE INVENTION The present invention has been made in view of the foregoing problems, and has as its object to provide a low-pressure casting apparatus capable of preventing a shortage of pressurization time near a gate or a shrinkage cavity caused by collapse of directional solidification, thereby shortening a cycle time. It is to provide a device.

[0007]

SUMMARY OF THE INVENTION To solve the above problems,
In order to achieve the object, a low-pressure casting apparatus according to the present invention has the following configuration. That is, in a low-pressure casting apparatus in which the surface of a molten metal is pressurized to fill the molten metal into a mold through a molten metal injection path, a first temperature means for detecting the temperature of the molten metal, and a second temperature means for detecting the temperature of the molten metal. Temperature means; and control means for controlling cooling of the mold based on the molten metal temperature and the mold temperature detected by each of the means.

Preferably, first setting means for setting a cooling time of the mold when the temperature of the molten metal and the temperature of the mold are higher than set values, and when the temperature of only the mold is higher than a set value. The apparatus further includes second setting means for setting a cooling time of the mold, and third setting means for setting a cooling time of the mold when the molten metal temperature and the mold temperature are lower than set values.

[0009] Preferably, the mold is a mold used for casting a cylinder head of an automobile engine.

[0010] Preferably, a cooling means is provided for spot cooling a baseboard defining the shape of the intake port or the exhaust port of the cylinder head.

[0011]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

In the following, as an embodiment of the present invention, the cylinder head is formed by low pressure casting, but it goes without saying that the present invention can be applied to casting other than low pressure casting and casting of parts other than automobile parts.

[Structure of Low-Pressure Casting Die] FIG. 1 is a sectional view of a low-pressure casting mold of the present embodiment.

As shown in FIG. 1, a low-pressure casting mold 1 according to this embodiment is used for casting, for example, an aluminum cylinder head of an automobile engine, and has an upper mold base 2.
, A lower mold 5 fixed on a lower mold base 4, metal baseboards 6, 7 sandwiching the upper mold 3 and the lower mold 5 to define the side surfaces of the cavity, and a cavity. It has port cores 9 and 10 made of sand or the like for forming a hollow portion serving as an intake port or an exhaust port therein, and a side core 8 for molding the shape of the port peripheral portion.

The upper die 3 is provided with a plug port transfer die 11 serving as a plug insertion port at a portion corresponding to a position directly above the combustion chamber. A combustion chamber transfer mold 12 for transferring the shape of the combustion chamber is formed in the lower mold 5, and a cylindrical shape that opens into a cavity around the combustion chamber transfer mold 12 and serves as a gate for pouring molten metal. Gate sleeves 13 and 14 are provided. The sprue sleeves 13 and 14 are connected to a molten metal distribution chamber 17 provided at a lower portion of the lower mold base 4 through cylindrical molten metal passage members 15 and 16 serving as paths for feeding the molten metal into the cavity.
Is communicated to. The molten metal distribution chamber 17 is provided with a molten metal supply device 50.
It is connected to Stokes 18 which plays the role of a nozzle for introducing molten metal from (see FIG. 2).

The molten metal pressurized by the molten metal supply device 50 is introduced from the Stokes 18 into the molten metal distribution chamber 17, passes from the molten metal distribution chamber 17 through the molten metal passage members 15, 16, and is added into the cavity from the sprue sleeves 13, 14. It is pressure-filled. In the case of low pressure casting of an aluminum casting, the pressing time to the mold is set to about 220 seconds, and the cooling time is set to about 50 seconds. Also,
The molten metal in the molten metal supply device 50 has a surface of about 0.6 k.
Pressurized at g / sq cm.

The low-pressure casting mold 1 of the present embodiment is a so-called two-cavity type in which two identical molds are provided on the left and right with respect to the center line L.

The low-pressure casting mold 1 of the present embodiment is provided with a cooling mechanism for controlling the mold temperature. That is, the baseboard 6 is formed with the first refrigerant passage 20 for circulating water or air therein for cooling. The first refrigerant passage 20 is communicated from the first inlet 21 to the first outlet 22 through the inside of the baseboard 6. Water or air is sent to the first inlet 21 by a pump (not shown), circulates inside the baseboard 6 and is discharged from the first outlet 22.

The baseboard 7 is provided with a second refrigerant passage 23 for circulating water or air therein for cooling. The second refrigerant passage 23 communicates from the second inlet 24 to the second outlet 25 through the inside of the baseboard 7. Water or air is sent to the second inlet 24 by a pump (not shown), circulates inside the baseboard 7 and is discharged from the second outlet 25.

A third refrigerant passage 26 for circulating water or air therein for cooling is formed in the plug opening transfer mold 11 of the upper mold 3. The third refrigerant passage 26 communicates from the third inlet 27 to the third outlet 28 through the inside of the plug port transfer mold 11. Water or air is sent to the third inlet 27 by a pump (not shown), and the
And is discharged from the third discharge port 28.

A fourth refrigerant passage 2 for circulating water or air therein to cool the combustion chamber transfer mold 12 of the lower mold 5 is provided.
9 are formed. The fourth refrigerant passage 29 is connected to the fourth inlet 3
0 to the fourth discharge port 31 through the inside of the combustion chamber transfer mold 12.
Is communicated to. Water or air is sent into the fourth inlet 30 by a pump (not shown), circulates inside the transfer chamber 12, and is discharged from the fourth outlet 31.

[Mold Cooling Control] Next, the mold cooling control method of the present embodiment will be described. In the following, only the cooling of the baseboards 6 and 7 will be described for convenience, but it goes without saying that the cooling of the plug port transfer mold 11 and the combustion chamber transfer mold 12 can be controlled by the same method.

FIG. 2 is a block diagram for realizing the cooling control of the mold according to the present embodiment.

As shown in FIG. 2, the cooling control of the baseboards 6, 7 is executed by the controller 40. Controller 4
Numeral 0 denotes an arithmetic processing unit including a general CPU, ROM, RAM and the like.

The baseboards 6 and 7 are provided with temperature sensors 35 and 36 for detecting their temperatures, respectively.
Reference numerals 5 and 36 are electrically connected to the controller 40, and detection outputs of the respective sensors are output to the controller 40.
The controller 40 calculates the temperatures of the baseboards 6, 7 based on these sensor detection outputs.

The molten metal supply device 50 is provided with a temperature sensor 37 for detecting the temperature of the molten metal.
7 is also electrically connected to the controller 40, and its detection output is output to the controller 40. Controller 40
Calculates the temperature of the molten metal based on these sensor detection outputs.

A solenoid valve 38 is provided at the inlet 21 of the first refrigerant passage 20.
Are electrically connected to the controller 40. The controller 40 controls the solenoid valve 38 to open and close under predetermined setting conditions to control the flow time of water or air to the first refrigerant passage and the flow start and end times. Further, a solenoid valve 39 is provided at the inlet 24 of the second refrigerant passage 23, and the solenoid valve 39 is connected to the controller 40.
Is electrically connected to The controller 40 controls the solenoid valve 39 to open and close under predetermined setting conditions to control the time of flow of water or air to the second refrigerant passage, and the start and end times of flow.

Except for the above-mentioned structure, the same members as those shown in FIG.

FIG. 3 is a diagram showing conditions for executing cooling control based on the temperature of the molten metal and the temperature of the mold. FIG. 4 shows FIG.
FIG. 3 is a diagram showing the setting conditions of the first embodiment in detail.

Based on the temperature relationship between the temperature of the molten metal and the temperature of the mold, the controller 40 controls the mold to prevent shrinkage cavities caused by insufficient pressurization time near the gate (gate gate) and collapse of directional solidification. Is partially forcibly controlled for cooling.

For example, the cooling of the baseboards 6 and 7 will be described as an example. As shown in FIG. 3, when the temperature of the molten metal is about 710 ° C. or more and the temperature of the mold (baseboards 6 and 7) is about 490 ° C. or more, The opening and closing of the solenoid valves 38 and 39 are controlled based on the setting condition A, and when the temperature of the molten metal is less than about 710 ° C., the mold (baseboard 6,
7) When the temperature is about 490 ° C. or higher, the opening and closing of the solenoid valves 38 and 39 are controlled based on the set condition B, and when the temperature of the molten metal is less than about 710 ° C. and the temperature of the mold (baseboard 6 and 7) is about 49
When the temperature is less than 0 ° C. and about 450 ° C. or more, the opening and closing of the solenoid valves 38 and 39 are controlled based on the setting condition C, and the temperature of the molten metal is less than about 710 ° C. and the temperature of the mold (baseboards 6 and 7) is about 4 ° C.
When the temperature is lower than 50 ° C., the opening / closing control of the solenoid valves 38 and 39 is not performed.

As shown in FIG. 4, under the set condition A, for example, after waiting for about 150 seconds, the solenoid valves 38 and 39 are opened for about 30 seconds and the first and second refrigerant passages 20 and 2 are opened.
3 circulate water or air. In the setting condition B, for example, after waiting for about 150 seconds, the solenoid valves 38 and 39 are opened for about 20 seconds and the first and second refrigerant passages 20 and 2 are opened.
3 circulate water or air. In the setting condition C, for example, after waiting for about 150 seconds, the solenoid valves 38 and 39 are opened for about 10 seconds to open the first and second refrigerant passages 20 and 2.
3 circulate water or air.

It should be noted that the plug port transfer type 11 and the combustion chamber transfer type 1
Regarding the cooling control 2, the threshold temperature, the water flow (air) time, and the like in FIGS. 3 and 4 may be appropriately changed. Further, the controller 40 independently controls the water flow (air) to the baseboards 6 and 7, the plug port transfer mold 11 and the combustion chamber transfer mold 12 according to the temperature of each part.

According to this embodiment, the following effects can be obtained.

The cooling rate of the molten metal is adjusted to the temperature of the molten metal and the temperature of the mold by changing the flow time (air) according to the temperature of the molten metal and the temperature of the mold. Since the mold can be partially cooled, the cycle time of casting can be shortened.

Further, since part of the mold is forcibly cooled, shrinkage cavities generated near the gate due to shortage of pressurizing time can be suppressed particularly when the temperature of the molten metal is higher than the set temperature.

Further, since the collapse of the directional solidification of the molten metal is suppressed by cooling the mold, shrinkage cavities generated near the gate can be suppressed.

It should be noted that the present invention can be applied to modifications or changes of the above embodiment without departing from the spirit thereof.

[0039]

As described above, according to the present invention, in the low pressure casting apparatus, the cooling of the mold is controlled based on the temperature of the molten metal and the temperature of the mold. It is possible to prevent shrinkage cavities caused by the collapse of the lands and shorten the cycle time.

[0040]

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a low-pressure casting mold according to an embodiment.

FIG. 2 is a block diagram for realizing mold cooling control of the present embodiment.

FIG. 3 is a diagram showing conditions for executing cooling control based on a molten metal temperature and a mold temperature.

FIG. 4 is a diagram showing the setting conditions of FIG. 3 in detail.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Low-pressure casting mold 2 ... Upper mold base 3 ... Upper mold 4 ... Lower mold base 5 ... Lower mold 6, 7 ... Skirting board 8 ... Side core 9, 10 ... Port core 17 ... Distribution chamber 18 ... Stokes 20 ... 1st refrigerant passage 23 ... 2nd refrigerant passage 26 ... 3rd refrigerant passage 29 ... 4th refrigerant passage 38, 39 ... temperature sensor 40 ... controller 50 ... molten metal supply device

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor: Kenji Tomiya 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Co., Ltd.

Claims (4)

[Claims] 1. A low-pressure casting apparatus for filling a molten metal into a mold through a molten metal injection path by pressurizing the surface of the molten metal, wherein: a first temperature means for detecting the temperature of the molten metal; A low-pressure casting apparatus comprising: a second temperature unit; and a control unit that controls cooling of the mold based on a molten metal temperature and a mold temperature detected by each unit. 2. A first setting means for setting a cooling time of the mold when the melt temperature and the mold temperature are higher than set values, and cooling the mold when only the mold temperature is higher than a set value. The apparatus according to claim 1, further comprising: second setting means for setting a time; and third setting means for setting a cooling time of the mold when the molten metal temperature and the mold temperature are lower than set values. 2. The low-pressure casting apparatus according to 1. 3. The low pressure casting apparatus according to claim 2, wherein the mold is a mold used for casting a cylinder head of an automobile engine. 4. The low-pressure casting apparatus according to claim 3, further comprising cooling means for spot cooling a baseboard defining a shape of an intake port or an exhaust port of the cylinder head.