JPH0531564A - Method for controlling pressurized timing for squeeze pin in partial squeeze casting - Google Patents

Abstract

PURPOSE:To prevent unevenness of the quality and to obtain a product having the fixed quality by detecting temp. of a die with a die temp. sensor and setting moving timing or moving velocity for a squeeze pin. CONSTITUTION:Molten metal supplied in an injection sleeve 16 is filled up into cavity 15 with an injection plunger 17 by pressurizing. At the same time, the temp. of movable die 13 is measured through the die temp. sensor 25 under existence of control 24 and a control signal is outputted to a hydraulic unit 20, and the moving timing for the squeeze pin 18 is set with a timer or the moving velocity for the squeeze pin 18 is set by adjusting opening degree of a flow rate control valve 25. The squeeze pin 18 is projected into the cavity 15 through the squeeze cylinder 19 with this setting moving timing or moving velocity to partially pressurize the molten metal. After that, by holding the pressurized condition for the prescribed time, the molten metal in the cavity 15 is solidified.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to local squeeze casting in which molten metal filled in a cavity of a mold is locally pressurized by a squeeze pin to prevent the formation of porosity.
The present invention relates to a squeeze pin pressing timing control method for pressing a squeeze pin at an appropriate timing for each shot.

[0002]

2. Description of the Related Art For example, in the case of manufacturing a die casting product or a squeeze casting product, when the molten metal filled in the cavity of the mold is cooled and solidified, the volume of the molten metal shrinks to form a porosity. Therefore, local squeeze casting has been conventionally performed in order to prevent the occurrence of such blowholes.

In the above-mentioned local squeeze casting, as shown in FIG. 3, a squeeze cylinder 4 is formed in a portion of a cavity 3 formed by a fixed mold 1 and a movable mold 2 where a cavity is likely to occur.
A squeeze pin 5 that can be pushed in is provided by the squeeze pin 5 by the squeeze cylinder 4 immediately before the molten metal filled in the cavity 3 is solidified by the injection plunger 7 in the injection sleeve 6. The squeeze pin 5 locally pressurizes the molten metal filled in the cavity 3 so as to prevent the formation of porosity.

Conventionally, in the local squeeze casting in which the squeeze pin 5 is projected into the cavity 3 as described above and the molten metal immediately before solidification is locally pressurized, the squeeze pin 5 is pressed to the molten metal in the cavity 3. The operation timing or operation speed of the pin 5 has been fixedly set in advance by a timer, a throttle valve or the like aiming at the greatest common divisor of proper timing.

[0005]

By the way, as described above, when the operation timing of the squeeze pin 5 is fixedly set by the timer, the throttle valve, etc., when the temperature of the mold is low at the initial stage of casting, As shown in FIGS. 4 (a) and 4 (b), the solidification progress state of the molten metal filled in the cavity 3 is different from the case where the temperature of the mold is high in a steady state of accumulated shots. The timing is not optimal for this shot. As a result, there is a problem in that shots in which the defects inside the casting are not sufficiently resolved occur. Incidentally, FIG.
(A) and (b) are the operation timing of the squeeze pin 5 fixedly set, when the temperature of the die in the initial stage of casting is low and when the temperature of the die in a steady state of accumulated shots is high. 7 shows the progress of solidification of the molten metal in the cavity 3 in which 8 is a solidified portion (solid layer portion), 9 is a half solidified portion (solid liquid coexisting layer portion), and 10 is not solidified yet. It is a part (liquid layer part).

In order to solve the above problem, for example, in Japanese Patent Laid-Open No. 2-75460, the pressing stroke of the squeeze pin is measured every shot, and the required pressing stroke can be secured from this measured value. It is proposed that the pressurizing timing is calculated and the subsequent pressurizing operation of the squeeze pin is controlled by the pressurizing timing. However, it is not possible to provide a pressurizing stroke measuring means for the squeeze pin in the mold. However, there is a problem in that it is very difficult in terms of die design and in terms of space, and that it is necessary to provide each die with a squeeze pin pressure stroke detection means, which leads to an increase in equipment cost.

The present invention has been made in view of the above-mentioned problems of the prior art, and a squeeze pin pressurizing timing is set so as to ensure proper timing for each shot, so that a product of constant quality can be obtained. It is an object of the present invention to provide a method for controlling the pressurization of a squeeze pin in local squeeze casting that can achieve the above.

[0008]

In order to achieve the above-mentioned object, the present invention locally fills the molten metal by injecting the molten metal into the cavity with an injection plunger and then projecting the squeeze pin into the cavity with a squeeze cylinder. In local squeeze casting under pressure, the die temperature is detected by a die temperature sensor, and the squeeze pin pressing timing control method in local squeeze casting is configured to feedback control the operation timing or operation speed of the squeeze pin based on the detected temperature. I will provide a.

[0009]

In the present invention, the mold temperature, which is the representative value of the solidification progress rate of the molten metal in the cavity, which has the greatest influence on the proper timing of the operation of the squeeze pin, is measured, and the operation timing of the squeeze pin or the mold temperature is measured based on this mold temperature. Since the operation speed is feedback-controlled, proper timing can be obtained for each individual shot.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for controlling a squeeze pin pressing timing in local squeeze casting according to the present invention will be described below with reference to FIGS.

In FIG. 1, 11 is a fixed mold held by a fixed mold plate 12, 13 is a movable mold mounted on a movable mold plate 14, and a cavity corresponding to the shape of the product is formed on the abutting surface thereof.
15 are formed. 16 is a fixed mold 11 and a fixed mold plate 12
Is an injection sleeve mounted on the and is communicated with the cavity 15 through the runner and the gate. 17 is an injection sleeve
An injection plunger slidably inserted in 16 is integrally connected to an injection cylinder (not shown). Fill with pressure. Reference numeral 18 denotes a squeeze pin slidably supported by a movable mold 13, the front end of which is located facing the cavity 15 and the rear end of which is integrally connected to a squeeze cylinder 19. By projecting the tip into the cavity 15, the molten metal filled in the cavity is locally pressurized. 20 is a hydraulic unit connected to the squeeze cylinder 19 via a pipe 21 and a pipe 22, by supplying high pressure oil to the head side of the squeeze cylinder 19 via the pipe 21, the squeeze pin 18 is projected into the cavity 15, Further, by supplying high pressure oil to the rod side of the squeeze cylinder 19 via the pipe 22, the squeeze pin 18 is retracted. 23 is a movable mold 13
At an arbitrary position, that is, a mold temperature sensor including a thermocouple provided in the vicinity of a portion where the molten metal is locally pressurized in the cavity 15, so that an electric output signal is output according to the temperature of the movable mold 13. Is becoming 24 is a control device connected to the output side of the mold temperature sensor 23, which processes the electric output signal of the mold temperature sensor 23 to measure the temperature of the movable mold 13, and is obtained in advance from experience from this measured value. A timer (not shown) outputs a control signal to the hydraulic unit 20 that operates the squeeze cylinder 19 so that the proper timing is reached (see FIG. 2).
The operation timing of the squeeze pin 18 is automatically set by using the squeeze pin 18 The operating speed of is set automatically.

With the above arrangement, the method of the present invention is carried out as follows.

First, after the fixed mold 11 and the movable mold 13 are closed to form the cavity 13, the molten metal supplied into the injection sleeve 16 is pressurized and filled into the cavity 15 by the injection plunger 17. At the same time, the control unit 24 moves the movable mold.
The temperature of 13 is measured via the mold temperature sensor 23, a control signal is output from the measured value to the hydraulic unit 20 and the operation timing of the squeeze pin 18 is set by a timer, or
Alternatively, the operation speed of the squeeze pin 18 is set by adjusting the valve opening degree of the flow control valve 25 provided in the middle of the pipe 21, and the squeeze cylinder 19 is set at the set operation timing or operation speed.
The squeeze pin 18 is further projected into the cavity 15 to locally pressurize the molten metal. Then, the pressurized state is maintained for a predetermined time to solidify the molten metal in the cavity 15. Then, after the molten metal in the cavity 15 is solidified, the hydraulic unit 21 supplies high pressure oil to the rod side of the squeeze cylinder 19 via the conduit 22 to return the squeeze pin 18 to its original position. Thus, when the squeeze pin 18 returns to its original position, the fixed mold 11 and the movable mold 13 are opened to take out the cast product.

[0014]

As described above, according to the present invention,
The mold temperature is detected by the mold temperature sensor, and the operation timing or operation speed of the squeeze pin is set based on the detected temperature value, so that proper timing can be obtained for each individual shot and the product quality will vary. Therefore, it is possible to always obtain products of constant quality regardless of production conditions. Also, since only the mold temperature sensor is installed in the mold, it is easy in terms of space and mold design, and
Since the squeeze pin and the squeeze cylinder are used as the means for detecting the filling state of the molten metal in the portion to be pressurized in the cavity, only the mold temperature sensor needs to be provided for each mold, so that the equipment cost can be reduced.

[Brief description of drawings]

FIG. 1 is a drawing showing a local squeeze casting apparatus for carrying out the method of the present invention.

FIG. 2 is a diagram showing a relationship between a mold temperature and operation timings and operation speeds of squeeze pins.

FIG. 3 is a drawing showing a local squeeze casting apparatus for carrying out a conventional method.

FIG. 4 (a) is an explanatory view showing the progress of solidification of the molten metal in the cavity when the temperature of the mold in the initial stage of casting is low.
(B) is an explanatory view showing a solidification progress state of the molten metal in the cavity when the temperature of the mold in a steady state in which shots are accumulated is low.

[Explanation of symbols]

 11 Fixed mold 13 Movable mold 15 Cavity 17 Injection plunger 18 Squeeze pin 19 Squeeze cylinder 20 Hydraulic unit 21 Piping 22 Piping 23 Mold temperature sensor 24 Controller 25 Flow control valve

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location B29C 45/56 6949-4F

Claims (1)

Claims: 1. A mold for local squeeze casting in which a molten metal is filled in the cavity by an injection plunger, and a squeeze pin is projected into the cavity by a squeeze cylinder to locally press the molten metal. A method for controlling pressurizing timing of a squeeze pin in local squeeze casting, wherein temperature is detected by a mold temperature sensor, and the operation timing or operation speed of the squeeze pin is feedback-controlled based on the detected temperature.