JPH0523821A - Method for controlling timing of pressurization to squeeze pin in partial squeeze casting - Google Patents

Abstract

PURPOSE:To obtain a product having the constant quality by controlling timing of pressurization so as to start the pressurizing movement to a squeeze pin when molten steel in cavity is always the same solidified condition. CONSTITUTION:In a partial squeeze casting for partially pressurizing the molten metal by projecting the squeeze pin 18 into the cavity 15 with a squeeze cylinder 19 after filling up the molten metal into the cavity 15 with an injection plunger 17, a pressure switch 20 arranged at the squeeze cylinder 19 is worked with pressure of the molten metal in the cavity 15 through the squeeze pin 18. Then, by working signal of this pressure switch 20, the timing of pressurization to the squeeze pin 18 is controlled.

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 method for controlling the timing of pressing a squeeze pin.

[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. 2, 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.

By the way, in the local squeeze casting in which the squeeze pin 5 is projected into the cavity 3 to locally pressurize the molten metal immediately before solidification as described above, the squeeze pin 5 locally pressurizes the molten metal in the cavity 3. In this case, as shown in FIG. 2, when the injection plunger 7 in the injection sleeve 6 advances rightward in the drawing to fill the cavity 3 with the molten metal, the dog 8 provided in the injection plunger 7 is fixed. The squeeze cylinder 4 is operated via a not-shown operation timer by a signal generated by hitting the limit switch 9 for detecting the position of the injection plunger set to the position, and the squeeze pin 5 performs the pressurizing operation.

[0005]

However, like the pressing operation by the squeeze pin 5 in the conventional local squeeze casting, the limit stitch for detecting the position of the injection plunger operated by the dog 8 provided in the injection plunger 7. When a start signal for pressurizing operation of the squeeze pin 5 is taken from 9, for example, after the start signal is output, due to variations in injection speed due to galling of the injection plunger 7, gate resistance, etc. Since the time is not constant, there is a variation in the solidified state of the molten metal in the cavity 3 at the start of pressurization of the squeeze pin 5, resulting in a variation in product quality.

Therefore, in order to eliminate the above-mentioned variation in product quality, for example, in Japanese Utility Model Laid-Open No. 2-22252, a squeeze pin 5 is added to a squeeze pin 5 from a pressure switch which detects a pressure rise of an injection cylinder at the completion of filling of molten metal. Although a device that receives a start signal of the pressure operation is proposed, since the pressure of the molten metal in the cavity 3 is detected through the injection plunger 7, it is possible to prevent galling of the injection plunger 7 and gate resistance. Therefore, there is a problem that the pressure of the molten metal in the cavity 3 is not accurately transmitted to the injection cylinder.

Further, in Japanese Patent Laid-Open No. 64-83360,
It has been proposed that the pressure of the molten metal in the cavity 3 is guided to a load cell via a detection rod and a start signal for operating the squeeze pin 5 is taken from this load cell. There is a problem in that the cost is high because it is necessary to provide the detecting means including the load cell, and the pressure of the molten metal in the cavity 3 is not accurately transmitted to the load cell due to the resistance due to the clogging of the detecting rod.

The present invention has been made in view of the above-mentioned conventional problems, and controls the pressurizing timing so as to start the pressurizing operation of the squeeze pin when the molten metal in the cavity is always in the same solidified state. Accordingly, it is an object of the present invention to provide a squeeze pin pressure control method in local slide casting that can obtain a product of constant quality.

[0009]

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 to press, the pressure switch provided in the squeeze cylinder via the squeeze pin is actuated by the pressure of the molten metal in the cavity, and in the local squeeze casting in which the pressure timing of the squeeze pin is controlled by the operation signal of this pressure switch. A squeeze pin pressing timing control method is provided.

[0010]

According to the present invention, the pressure switch provided on the squeeze cylinder is operated via the squeeze pin by the pressure of the molten metal in the cavity, and the pressurizing timing of the squeeze pin is controlled based on the operation signal of this pressure switch. Therefore, the pressing operation of the squeeze pin can always be started when the molten metal in the cavity is in the same solidified state, and a product of constant quality can be obtained.

[0011]

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

In FIG. 1, 11 is a fixed die held by a fixed die plate 12, 13 is a movable die attached to a movable die 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 fitted in 16 is connected to an injection cylinder (not shown). Reference numeral 18 denotes a squeeze pin slidably supported by the movable mold 13. The tip of the squeeze pin faces the cavity 15, and the rear end is connected to the cylinder piston 19a of the squeeze cylinder 19. Due to the cavity 15
It is configured to project inward. Reference numeral 20 is a pressure switch connected to a pipe line 22 connecting the head side 19A of the squeeze cylinder 19 and the hydraulic unit 21, and detects an increase in the pressure of the head side 19A of the squeeze cylinder 19, and an operation not shown in the figure is detected by the detection signal. The hydraulic unit 21 is operated via the timer. Reference numeral 23 is a pilot type check valve provided upstream of the pressure switch 20 in the pipe line 22. The check action is released by the hydraulic pressure generated in the pipe line 24 connecting the rod side 19B of the squeeze cylinder 19 and the hydraulic unit 21. To be done.

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

First, prior to filling the molten metal into the cavity 15 formed by the fixed mold 11 and the movable mold 13, hydraulic pressure is applied from the hydraulic unit 21 to the head side 19A of the squeeze cylinder 19 via the pipe line 22. By supplying, the squeeze cylinder 19 is operated and the piston 19a thereof is advanced by a predetermined stroke S as shown in FIG. Next, in this state, the injection plunger fitted in the injection sleeve 16
When the molten metal is filled in the cavity 15 by 17, the pressure of the molten metal in the cavity 15 is transmitted to the piston 19a of the squeeze cylinder 19 via the squeeze pin 18, so that pressure is generated on the head side 19A of the squeeze cylinder 19. Then, when the pressure of the molten metal in the cavity 15 reaches a predetermined pressure after a lapse of a predetermined time after the completion of the filling of the molten metal, the head side of the squeeze cylinder 19 is passed through the squeeze pin 18 and the piston 19a.
19A also reaches a predetermined pressure, the pressure switch 20 detects this and operates, and the detection signal causes the hydraulic pressure from the hydraulic unit 21 via the conduit 22 to the head side of the squeeze cylinder 19A.
The squeeze cylinder 19 is actuated and the piston 19a thereof is further advanced so that the squeeze pin 18 is 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, when the molten metal in the cavity 15 is solidified, hydraulic pressure is supplied to the rod side 19B of the squeeze cylinder 19 by the hydraulic unit 21 via the conduit 24, the piston 19a of the squeeze cylinder 19 is retracted, and the squeeze pin 18 is returned to its original position. Return to position. When the squeeze pin 18 returns to its original position, the mold is opened and the cast product is taken out.

As described above, since the method of the present invention detects the filling state of the molten metal in the portion to be pressurized in the cavity 15 and receives the start signal of the pressurizing operation of the squeeze pin 18, it is always in the cavity 15. The pressurizing timing can be controlled so that the pressurizing operation is started by the squeeze pin 18 when the molten metal is in the same solidified state.

[0016]

According to the present invention, since the filling state of the molten metal in the portion to be pressurized in the cavity is detected and the start signal of the pressurizing operation of the squeeze pin is obtained, variations in injection speed and the like are eliminated. It is possible to accurately and precisely control the timing of pressing the squeeze pin, and thereby a product of constant quality can be obtained. Further, 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, it is not necessary to provide a detecting means for each mold, so that the cost can be reduced and the squeeze pin can be used. Since the burr is discharged each time the pressurization, the mold opening and the extrusion are performed, the pressure of the molten metal in the cavity can be accurately transmitted to the squeeze cylinder without the pressure transmission failure due to the clogging of the burr.

[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 drawing showing a local squeeze casting apparatus for carrying out a conventional method.

[Explanation of symbols]

 11 Fixed mold 13 Movable mold 15 Cavity 17 Injection plunger 18 Squeeze pin 19 Squeeze cylinder 19a Piston 19A Head side 19B Rod side 20 Pressure switch 21 Hydraulic unit

Claims (1)

Claim: What is claimed is: 1. In local squeeze casting, in which a molten metal is filled into the cavity by an injection plunger, and then a squeeze pin is projected into the cavity by a squeeze cylinder to locally pressurize the molten metal. The pressure switch provided in the squeeze cylinder is operated via the squeeze pin by the pressure of the molten metal inside, and the pressurizing timing of the squeeze pin is controlled by the operation signal of this pressure switch. Pressurization timing control method.