JPH08117955A - Partial pressure casting method and device thereof - Google Patents

Abstract

PURPOSE: To provide a method and a device for partial pressure casting, by which plastic deformation and crack, etc., of a cast product can be prevented. CONSTITUTION: In the partial pressure casting method, by which molten metal 8 is filled into a cavity 4 by using an injection plunger 5 and thereafter, the molten metal 8 is partially pressurized by projecting a squeeze pin 2 into the cavity 4 with a squeeze cylinder 3 and after solidifying the molten metal, the die opening is executed, the solidifying condition of the molten metal at the time of pressurizing with the squeeze pin 2 is detected and the partial pressurizing with the squeeze pin 2 is released.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a local pressure casting method and apparatus using a squeeze pin, and more particularly to a method and apparatus for controlling pressure release timing of a squeeze pin.

[0002]

2. Description of the Related Art When manufacturing a casting such as a die casting, the volume of the molten metal filled in the cavity of the mold shrinks as it cools and solidifies. As a result, defects such as porosity occur in the product. Therefore, the local pressure casting method using a squeeze pin has been conventionally used as an effective countermeasure.

An example of a local pressure casting apparatus using a squeeze pin is the local pressure casting apparatus 9 shown in FIG. As shown in FIG. 3, this device 9 includes an injection plunger 5 for filling a molten metal 8 into a cavity 4 provided between a fixed die 10 and a movable die 11, and a squeeze pin 2 for projecting a squeeze pin 2 into the cavity 4. It consists of a cylinder 3.

When casting a product, first, a predetermined amount of molten metal 8 is poured into the injection sleeve 55. Next, the injection plunger 5 is advanced. As a result, the injection sleeve 5
The molten metal 8 in 5 passes through the runner 12 and the gate 13 and is filled in the cavity 4.

On the other hand, when the injection plunger 5 reaches a fixed position, a plunger position detector (not shown) outputs a plunger advancement completion signal to the squeeze controller 6. Based on this signal, the squeeze control device 6 causes the hydraulic unit 30 to
Send a pressurization start command to. As a result, the squeeze cylinder 3 operates and the squeeze pin 2 projects into the cavity 4. The protruding squeeze pin 2 locally and appropriately pressurizes the molten metal 8. As a result, it is possible to prevent the occurrence of porosity due to shrinkage during cooling and solidification.

[0006]

However, the above conventional local pressure casting method and apparatus have the following problems.
That is, the squeeze pin 2 protruding into the cavity 4 for preventing the formation of the porosity continues to be pressurized until the mold is opened even after the molten metal 8 is solidified. During this time, when the molten metal 8 is in a solid-liquid coexisting state, as shown in FIG.
The pressing force due to is sufficiently dispersed.

However, when the solid fraction of the molten metal 8 becomes high, the pressing force of the squeeze pin 2 becomes high compressive stress and shear stress at its abutting portion, as shown in FIG. Therefore, the cast product made by solidifying the molten metal 8 is
Due to the pressing force of the squeeze pin 2, the contact portion with the squeeze pin 2 and its periphery are plastically deformed or cracked.
Therefore, even if it is possible to suppress the occurrence of porosity, these defects may cause the product to become defective.

The present invention has been made in view of the above conventional problems, and an object of the present invention is to provide a local pressure casting method and apparatus capable of preventing plastic deformation, cracking and the like of a cast product. .

[0009]

According to the present invention, a molten metal is filled in a cavity using an injection plunger, and then a squeeze pin is projected into the cavity by a squeeze cylinder to locally pressurize the molten metal, and the mold is opened after the molten metal is solidified. In the local pressure casting method of performing the above, the local pressure casting method is characterized in that the molten metal solidification state at the time of pressurization by the squeeze pin is detected and the local pressurization by the squeeze pin is released.

The solidification state of the molten metal is detected by detecting the displacement speed, which is the amount of movement of the squeeze pin per unit time, and when the displacement speed reaches a predetermined value, the local addition by the squeeze pin is performed. It is preferable to release the pressure. As a result, even if various casting conditions such as the molten metal filling time and the mold temperature are changed, the pressure can be released at the optimum timing.

The predetermined value is preferably 30% to 0% of the maximum displacement speed when the squeeze pin is pressed. That is, it is preferable that the predetermined value is 30% or less of the maximum displacement speed of the squeeze pin, or the displacement speed of the squeeze pin is 0. As a result, the pressurization of the squeeze pin can be released at the optimum timing when the molten metal reaches the state immediately before solidification or the solidification complete state.

Further, the solidification state of the molten metal can be detected by detecting the pressure of the molten metal, and when the pressure reaches a predetermined value, the local pressurization by the squeeze pin can be released. This also provides the same effect as that of the means for detecting the displacement speed of the squeeze pin. Further, as a pressure detecting method, there are a method of detecting a pressing force of the squeeze pin, that is, a method of detecting a squeeze pressure, a method of detecting a molten metal pressure applied to the ejector pin, and the like. The ejector pin is provided in the mold to press the cast product after the mold is opened to release the cast product.

The mold opening performed after the solidification of the molten metal is performed by detecting the time when the local pressurization at the squeeze pin is released,
It is preferable to carry out after a predetermined time. As a result, even if there is a variation in the solidification time of the molten metal filled in the cavity due to variation in the mold temperature or the like, the mold opening can always be performed after a fixed time from the solidification of the molten metal. Therefore, it is possible to prevent the release force from increasing due to holding in the mold for a long time after the molten metal is solidified. Moreover, the unnecessary holding time can be omitted, and the average time of the casting cycle can be shortened.

As an apparatus for carrying out the above local pressure casting method, an injection plunger for filling the cavity with molten metal, a squeeze cylinder for projecting a squeeze pin into the cavity, and a pressurizing means for pressurizing the squeeze cylinder are provided. And a pressure release means for releasing the pressure applied to the squeeze pin based on a detection signal from the solidification state detection means, and a local pressure casting method. There is a device.

The solidification state detecting means is preferably a displacement speed detecting means for detecting the displacement speed of the squeeze pin. As a result, it is possible to obtain a local pressure casting device capable of exhibiting the above-mentioned effects by detecting the displacement speed of the squeeze pin.

The solidification state detecting means may be a molten metal pressure detecting means for detecting the pressure of the molten metal. By this,
By detecting the pressure of the molten metal, it is possible to obtain a local pressure casting device capable of exhibiting the above-mentioned effects.

Further, it is preferable that the local pressure casting apparatus is further provided with mold opening control means for performing mold opening based on a detection signal from the solidification state detecting means. This detects the time when the squeeze pin local pressure is released,
It is possible to obtain a local pressure casting device capable of performing mold opening after a predetermined time.

[0018]

In the local pressure casting method of the present invention, the molten metal filled in the cavity is locally pressed by the squeeze pin. Therefore, even if the molten metal shrinks as it cools and solidifies, no cavities occur in the cast product after the solidification of the molten metal. Furthermore, in the local pressure casting method of the present invention,
The molten metal solidification state during pressurization by the squeeze pin is detected, and the local pressurization by the squeeze pin is released. Therefore, in the cast product formed by the solidification of the molten metal, the contact part with the squeeze pin and its periphery are plastically deformed,
It does not break.

Further, in the local pressure casting apparatus of the present invention, the above excellent local pressure casting method can be carried out. Therefore, according to the present invention, it is possible to provide a local pressure casting method and apparatus capable of preventing plastic deformation, cracking and the like of a cast product.

[0020]

【Example】

Example 1 A local pressure casting method and apparatus according to an example of the present invention will be described with reference to FIGS. 1 and 2. As shown in FIG. 1, the local pressure casting apparatus 1 of this example includes an injection plunger 5 that fills a cavity 4 with a molten metal 8, a squeeze cylinder 3 that projects a squeeze pin 2 into the cavity 4, and a squeeze cylinder 3 thereof. It has a pressurizing means for pressurizing, a solidification state detecting means for detecting the solidification state of the molten metal, and a pressure releasing means for releasing the pressurization of the squeeze pin 2 based on a detection signal from the solidification state detecting means.

As shown in FIG. 1, the pressurizing means comprises a squeeze control device 6 for sending a pressurizing start command and a hydraulic unit 30 for actually controlling the squeeze cylinder 3. The pressurization start command is sent to the hydraulic unit 7 by the squeeze control device 6 based on a signal from a position detector (not shown) of the injection plunger 5.

As the solidification state detecting means, as shown in FIG. 1, a displacement sensor 60 disposed at the rear end of the squeeze pin 2 and a squeeze control device 6 for receiving output data of the displacement sensor 60. Displacement velocity detecting means constituted by The squeeze control device 6 converts the output data of the displacement sensor 60 into a displacement velocity by calculation and detects the time when the displacement velocity reaches a predetermined value. In this device, the above displacement speed is one of the maximum displacement speeds.
The time when it reaches 0% is set to a predetermined value.

The pressure release means is composed of the squeeze control device 6 and the hydraulic unit 30.
Then, the squeeze control device 6 sends a pressure release command to the hydraulic unit 30 based on the signal detected by the solidification state detecting means.

The apparatus 1 is also provided with mold opening control means for opening the mold based on the detection signal from the coagulation state detecting means. As shown in FIG. 1, the mold opening control means includes the squeeze control device 6 to the squeeze pin 2.
And a mold opening actuator (not shown) for receiving a pressure release signal. Based on the pressure release signal received from the squeeze control device 6, the mold opening control device 67 sends a mold opening command to the mold opening actuator 0.5 seconds later. Other configurations are the same as the conventional example.

Next, in order to perform local pressure casting using the local pressure casting apparatus 1 of this example, first, a predetermined amount of molten metal 8 is injected into the injection sleeve 55. Then, the injection plunger 55
Is advanced, and the molten metal 8 is injected and filled in the cavity 4 at the injection speed as shown by the injection speed curve 280 in FIG. On the other hand, when the injection plunger 5 reaches a predetermined value, a position detector (not shown) sends a squeeze controller 6 a plunger advancement completion signal.

Then, after a predetermined time, a pressure start command is sent to the hydraulic unit 30. Upon receiving the pressurization start command, the hydraulic unit 30 causes the squeeze pin 2 to project into the cavity 4 via the squeeze cylinder 3 and locally pressurizes the molten metal 8.

After that, the squeeze pin 2 is gradually displaced (advanced) as the molten metal 8 is cooled and solidified as shown by a squeeze pin displacement curve 200 in FIG. The displacement of the squeeze pin 2 is detected by the displacement sensor 60 and constantly output to the squeeze control device 6. The squeeze control device 6 calculates the output value and constantly detects the displacement speed of the squeeze pin 2.

Then, the squeeze control device 6 causes the displacement speed of the squeeze pin 2 to reach 10% of the maximum displacement speed (speed of the portion A in FIG. 2) (point B1 in FIG. 2). , A pressure release command is sent to the hydraulic unit 30. At the same time, the squeeze control device 6 sends a pressure release signal to the mold opening control device 67.

The hydraulic unit 30 which has received the pressure release command
Releases the pressure applied to the squeeze cylinder 2 via the squeeze cylinder 3. On the other hand, the mold opening control device 67, which has received the pressure release signal, opens the mold via the mold opening actuator 0.5 seconds later. Finally, by ejecting the ejector pin 7 into the cavity 4, the cast product is taken out, and a series of casting work is completed. After that, the same casting work is repeated. The curve 2 shown in FIG.
10 shows a transition of the casting pressure applied to the injection plunger 5.

Next, the function and effect of the local pressure casting method of this example will be described. In this example, similarly to the conventional example, the molten metal 8 filled in the cavity 4 is locally pressurized by the squeeze pin 2. Therefore, the molten metal 8 is cooled,
Even if it shrinks when it solidifies, no cavities occur in the cast product after the melt has solidified.

Further, in the local pressure casting method of this example, the solidified state of the molten metal from which the pressure on the squeeze pin 2 should be released is detected by detecting the displacement speed of the squeeze pin 2. Then, when the displacement speed reaches a predetermined value, the pressurization of the squeeze pin 2 is released.

As a result, the squeeze pin 2 has the molten metal 8 as shown in the conventional squeeze pin displacement curve 290 in FIG.
It is possible to eliminate the problem that the molten metal 8 is continuously pressurized locally until the mold is opened even after the solid phase ratio becomes high. That is, in the cast product formed by solidifying the molten metal 8, the contact portion with the squeeze pin 2 and its periphery are not plastically deformed or cracked.

Therefore, according to this example, by releasing the pressure applied to the squeeze pin according to the solidification state of the cast product, it is possible to prevent plastic deformation, cracking, etc. of the cast product.

Embodiment 2 The local pressure casting apparatus of this embodiment uses a molten metal pressure detecting means in place of the displacement speed detecting means as the solidification state detecting means in the apparatus 1 of the first embodiment. That is,
As shown in FIG. 1, a pressure sensor 70 for detecting the pressure of the molten metal is provided at the rear end of the ejector pin 7. The pressure sensor 70 constantly detects the pressure of the molten metal during pressurization of the squeeze pin 2, and sends the molten metal pressure data to the squeeze control device 6 via the amplifier 72.

When the squeeze control device 6 receives the molten metal pressure data, the squeeze control device 6 receives the molten metal pressure data at the time when the molten metal pressure reaches a predetermined value.
Similarly to the above, a pressure release command is sent to the hydraulic unit 30. Further, when the molten metal pressure detected by the pressure sensor 70 has two peaks P1 and P2 as shown in the molten metal pressure curve 270 of FIG. 2, the above-mentioned predetermined value becomes the above-mentioned second peak P2. It is set. Therefore, in this example, the point B2 in FIG. 2 where the peak P2 appears reaches a predetermined value.

The other structure is the same as that of the first embodiment.
In this example, the same effect as in Example 1 is obtained. Further, in this example, the pressure sensor 7 connected to the ejector pin 7 is used as the solidification state detecting means.
Therefore, even when the squeeze pin causes a sliding failure, it is possible to reliably detect the solidification state of the molten metal.

Embodiment 3 The local pressure casting apparatus of this embodiment is similar to the local pressure casting apparatus of Embodiment 2 except that instead of the pressure sensor 75 provided behind the ejector pin 7 used as the molten metal pressure means, a squeeze pin is used. A pressure sensor (not shown) that is connected to No. 2 and measures the squeeze pressure is used. Further, the squeeze pressure increases almost monotonically as shown by the squeeze pressure curve 250 in FIG. Therefore, the predetermined value in this example is set to 120 MPa (megapascal). Therefore, in this example, the point B3 shown in FIG. 2 reaches the predetermined value. Other configurations, signal exchange, etc. are the same as in the second embodiment.

In this example, the same effect as in Example 2 can be obtained. In this example, squeeze pressure is used as the solidification state detecting means. Therefore, it is possible to provide the pressure sensor outside the mold without constructing a displacement gauge or a pressure sensor inside the mold.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a local pressure casting device according to a first embodiment.

FIG. 2 is a diagram illustrating a squeeze pin pressure release timing according to the first, second, and third embodiments.

FIG. 3 is an explanatory view of a conventional local pressure casting apparatus.

FIG. 4 is a view for explaining a locally pressurized state of molten metal in a solid-liquid coexisting state according to a conventional example.

FIG. 5 is a view for explaining a locally pressurized state of a molten metal having a high solid fraction according to a conventional example.

[Explanation of symbols]

 1. . . Local pressure casting device, 10. . . Fixed type, 11. . . Movable type, 2. . . Squeeze pin, 200. . . Squeeze pin displacement curve, 250. . . Squeeze pressure curve, 270. . . Molten metal pressure curve, 3. . . Squeeze cylinder, 4. . . Cavity, 5. . . Injection plunger, 6. . . Squeeze control device, 60. . . Displacement sensor, 67. . . Mold opening control device, 7. . . Ejector pin, 75. . . Pressure sensor, 8. . . Molten metal,

Claims (9)

[Claims] 1. A local pressurization in which the molten metal is filled in the cavity by using an injection plunger, and then the squeeze pin is projected in the cavity by a squeeze cylinder to locally press the molten metal, and the mold is opened after solidification of the molten metal. In the casting method, a local pressure casting method is characterized in that the molten metal solidification state at the time of pressurization by the squeeze pin is detected and the local pressurization by the squeeze pin is released. 2. The method according to claim 1, wherein the molten metal solidification state is detected by detecting a displacement speed of the squeeze pin, and when the displacement speed reaches a predetermined value,
A local pressure casting method characterized by releasing the local pressure applied by the squeeze pin. 3. The predetermined value according to claim 2, wherein the predetermined value is 30% to 0% of a maximum displacement speed when the squeeze pin is pressed.
The method for local pressure casting according to claim 1. 4. The method according to claim 1, wherein the molten metal solidification state is detected by detecting the pressure of the molten metal, and when the pressure reaches a predetermined value, the local pressurization by the squeeze pin is released. A local pressure casting method characterized by: 5. The method according to any one of claims 1 to 4,
A local pressure casting method comprising detecting a point of time when the local pressure is released on the squeeze pin and performing mold opening after a predetermined time. 6. An injection plunger for filling the cavity with molten metal, a squeeze cylinder for projecting a squeeze pin into the cavity, a pressurizing means for pressurizing the squeeze cylinder, and a solidification state detecting means for detecting the solidification state of the melt. ，
A local pressure casting device comprising: a pressure releasing means for releasing the pressure applied to the squeeze pin based on a detection signal from the solidification state detecting means. 7. The local pressure casting apparatus according to claim 6, wherein the solidification state detecting means is a displacement speed detecting means for detecting a displacement speed of the squeeze pin. 8. The local pressure casting apparatus according to claim 6, wherein the solidification state detecting means is a molten metal pressure detecting means for detecting the pressure of the molten metal. 9. The method according to any one of claims 6 to 8,
A local pressure casting apparatus further comprising mold opening control means for performing mold opening based on a detection signal from the solidification state detecting means.