JP2003245768A - Die casting method and injection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a die casting method for improving the quality of casting and to prevent molten metal from waving in an injection sleeve without complicating and enlarging the mold. <P>SOLUTION: Molten metal M is supplied into an injection sleeve 13 from a ladle 3 through a molten metal supplying hole 11 (1), the differential wave F (2) generated at the molten metal supplying part is collided with the front edge of a plunger chip 4 so that the front surface of the molten metal rises. The rise of the molten metal surface is detected by a laser displacement sensor 16 through the molten metal supplying hole 11 (3), and when the molten metal surface is exceeded the reference value, the plunger chip 4 is advanced by sending a start command from a control means to a moving means. And the waving of the molten metal surface by the progress of the plunger chip 14 aligns the reflective wave of the differential wave F, and the molten metal M becomes a big mass M" on the front surface of the plunger chip 14 and is made to flow forward (4), and the molten metal M is thereby prevented from waving and an air trap into the molten metal M is also prevented. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a die casting method and an injection device used for carrying out the die casting method.

[0002]

2. Description of the Related Art Generally, in die casting, FIG.
As shown in, inside the injection sleeve 2 having the hot water supply port 1,
The molten metal M is quantitatively supplied from the ladle 3 through the hot water supply port 1 (), and after the completion of the hot water supply, the plunger tip 4 is advanced () by a driving means (not shown) at a predetermined timing, and the front end side of the injection sleeve 2 is shot. The molten metal is injected from the outlet 5 into the cavity (not shown) of the mold at high pressure ().

[0003]

By the way, in the above die casting method, a wave is generated in the molten metal M in the injection sleeve 2 by the hot water supplied from the ladle 3, and this wave is generated.
As the plunger tip 4 advances, it amplifies to generate ripples M'as shown in FIG. 5, and in some cases, the ripples M'become excessive, resulting in molten metal M'as shown in FIG.
The air layer A was trapped inside the steel, which was a major cause of deterioration of casting quality. Note that, for example, in Japanese Patent Laid-Open No. 62-68667, an internal volume of the injection sleeve is made variable by moving a shunt placed inside the opening of the tip of the injection sleeve by an actuator so that 100% of the molten metal is contained in the injection sleeve. After filling, the shunt is retracted in synchronism with the forward movement of the plunger tip to prevent the formation of an air layer.
However, in such a measure, since the actuator for moving the shunt has to be provided in the mold, the mold becomes complicated and large in size, and maintenance becomes troublesome, so that an increase in cost burden cannot be avoided.

The present invention has been made in view of the above-mentioned conventional problems, and its object is to suppress the ripple phenomenon of the molten metal in the injection sleeve without causing the mold to be complicated and upsized. It is an object of the present invention to provide a die casting method which greatly contributes to the improvement of casting quality, and also to provide an injection apparatus which can efficiently carry out the die casting method.

[0005]

Means for Solving the Problems As a result of various studies on the above-mentioned ripple phenomenon, the inventors of the present invention have found that, immediately after the hot water supply by the ladle 3 is finished, a step wave in which the surface of the hot water temporarily drops is generated. The wave collides with the front end of the plunger tip 4, and the reflected wave swells at the tip end side of the injection sleeve 2.
We came to the conclusion that there is a cause for rising as ´. The die casting method according to the present invention has been made based on the above-mentioned examination results, and is characterized in that the molten metal supplied into the injection sleeve is injected into the cavity of the die by the advance of the plunger tip. In the method, after the hot water supply is completed, the height of the surface of the front surface of the plunger tip is detected by a sensor, and the plunger tip is advanced based on the detection result. In the die casting method performed in this way, the sensor monitors the rise of the molten metal level when the step waves formed immediately after the hot water has collided with the plunger chip, and when the molten metal level rises appropriately, the plunger chip is By advancing, the rising of the molten metal on the front surface of the plunger tip and the reflected wave of the step wave are synchronized with each other to flow as a large lump and the occurrence of waviness is suppressed. In this case, it is desirable to move the plunger tip forward when the height of the molten metal on the front surface of the plunger tip exceeds the reference value set in the previous stage to reach the peak. And the reflected wave of the step wave are surely synchronized. On the other hand, the features of the die casting casting injection device according to the present invention include an injection sleeve having a hot water supply port, and a plunger chip slidably disposed on the injection sleeve,
In a die casting casting injection device having a driving means for driving the plunger tip, a non-contact displacement sensor for detecting the height of the molten metal surface in front of the plunger chip through the hot water supply port is provided, and a signal from the displacement sensor is provided. A control means for controlling the operation of the drive means based on the above is provided. In the injection apparatus thus configured, the non-contact type displacement sensor can be used to easily detect the height of the molten metal surface from the outside of the injection sleeve through the hot water supply port.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows the overall structure of a die casting apparatus including an injection apparatus according to the present invention. In the figure, 10 is an injection device according to the present invention, and 20 is a mold. The injection device 10 has a hot water supply port 11 at the base end and an injection port 12 at the tip end as in the conventional case (FIG. 5). Each of the injection sleeves 13 has an injection sleeve 13, and the injection sleeve 13 is arranged with its tip end coupled to the mold 20. The mold 20 is configured such that one side to which the injection sleeve 13 is coupled is a fixed mold 21 and the other side facing the fixed mold 21 is a movable mold 22, and the movable mold 22 is fitted to the fixed mold 21. In the closed state, that is, in the mold closed state, a cavity 23 as a casting space and a runner portion 24 for guiding the injection port 12 of the injection sleeve 13 to the cavity 23 are defined between them. Here, for convenience of description, the injection sleeve 13 is shown as a bottomed structure in which the tip is closed, but in reality, the tip of the injection sleeve 13 is opened and the injection sleeve 13 is movable inside this open end. It has a mold structure in which the shunts mounted inside the mold 22 are arranged.

The injection device 10 also includes an injection sleeve 13.
And a driving means 15 for driving the plunger tip 14. The plunger tip 14 is in the original position in the state shown in the drawing, which is brought closer to the base end side of the injection sleeve 13, and the hot water supply port 11 is opened immediately before the plunger tip 14 positioned in this original position. Is provided on the top of the injection sleeve 13.

The injection apparatus 10 further includes a laser displacement sensor (laser displacement meter) 16 and the laser displacement sensor 16
Control means 17 for controlling the operation of the drive means 15 based on the signal from the. Laser displacement sensor 16
Is fixedly positioned directly above the hot water supply port 11 with the laser emission port facing downward. The laser displacement sensor 16 plays a role of detecting the height of the molten metal surface on the front surface of the plunger tip 14, emits the laser to the molten metal M in the injection sleeve 13 through the hot water supply port 11, and the upper surface of the molten metal M (the molten metal). It has a function of receiving the reflected light of the laser reflected by the surface. The laser displacement sensor 16 can be changed to another non-contact type displacement sensor, for example, an ultrasonic sensor, an infrared sensor, a millimeter wave radar, or the like. On the other hand, the control means 17 compares the molten metal level detected by the laser displacement sensor 16 with a preset value (reference value) stored in advance, and when the molten metal height exceeds the set value, the drive means 15 is driven.
Has a function of sending an output command to the driving means 15
Moves the plunger tip 14 forward in response to the output command from the control means 15.

Hereinafter, an embodiment of die casting using a die casting apparatus equipped with the injection apparatus 10 having the above construction will be described with reference to FIG. In casting, first, as shown in FIG. 2, the ladle 3 is carried in above the hot water supply port 11 of the injection sleeve 13, and the molten metal M is supplied from the ladle 3 through the hot water supply port 11 into the injection sleeve 13. At this time, the ladle 3 is carried in above the hot water inlet 11 from an oblique direction in a plan view so as not to interfere with the laser displacement sensor 16 and the laser light. Immediately after the hot water is supplied from the ladle 3, as shown in FIG. 2, a step wave F in which the surface of the hot water temporarily lowers is generated, and the step wave F collides with the front end of the plunger tip 4. Then, the water level in front of it rises.
Therefore, in the present embodiment, as shown in FIG.
Laser displacement sensor 16 at the same time when hot water supply by the ladle 3 is completed
Further irradiation is performed to continuously detect the height of the molten metal surface on the front surface of the plunger tip 4 through the hot water supply port 11. The signal of the laser displacement sensor 16 is sent to the control means 17 (FIG. 1), and the control means 17 compares the measured value by the laser displacement sensor 16 with the reference value to measure the measured value When the (height) exceeds the reference value, an output command is sent to the driving means 15, whereby the plunger tip 14 starts to move forward. The irradiation by the laser displacement sensor 16 may be started at the same time as the hot water supply is started, and in this case, the measurement is started at the same time as the hot water supply is finished.

By the way, the step wave F that collides with the front end of the plunger tip 14 moves forward as a reflected wave after the molten metal rises on the front surface of the plunger tip 14. Therefore, in the present embodiment, a change in the height of the molten metal on the front surface of the plunger tip 14 is measured in advance by an experiment, and FIG.
As shown in, the reference value A to be set in the control means 17 is determined before the rise of the molten metal reaches the peak P. Therefore, at the point B when the plunger tip 14 starts to move forward, the plunger tip 14 moves forward immediately before the reflected wave of the step wave F is generated, and as a result, the rise of the molten metal surface due to the forward movement of the plunger tip 14 occurs. The reflected wave of the step wave F is synchronized with each other, and as shown in FIG. 2, the molten metal M flows forward as a large lump M ″ on the front surface of the plunger tip 14. That is, in front of the plunger tip 14. Waviness M ′ (FIG. 5) does not occur, whereby the air in the injection sleeve 13 precedes the molten metal M and the cavity 2 in the mold 20.
3 and is discharged to the outside of the mold 20 by the subsequent molten metal. Therefore, according to the die casting in this way, it is possible to obtain a good quality cast product with extremely few casting defects such as blow holes.

[0012]

EXAMPLE Using a die casting machine having a mold clamping force of about 880 × 10 ⁴ N, molten aluminum of 690 ° C. from the hot water inlet 11 was injected into the injection sleeve 13 preheated to 250 ° C. at 2 kg / s.
Hot water is supplied at the speed of 1 and plunger tip 1
When the level of the molten metal on the front of 4 exceeds 50 mm (A) (B)
And, the forward movement of the plunger tip 14 is started at three points, that is, 0.2 s and 0.4 s later than this point (injection start).
First, at a speed of 0.5 m / s up to a stroke of 400 mm,
Thereafter, the speed was increased to 2.5 m / s and the plunger tip 14 was advanced to a stroke of 550 mm to fill the cavity 23 with the molten metal, and a thin plate test piece having a size of 2.5 × 450 × 500 mm and a weight of 1.5 kg was cast. Then, after casting, each test piece was inspected for an internal defect by an X-ray transmission test, and the area of the internal defect was obtained.

FIG. 4 shows the inspection result of the internal defect. From this, the injection started at the time (B) before the rise of the molten metal surface reaches the peak P has the smallest internal defect. The later the time is (the delay time 0.2s,
0.4 s), internal defects are expanding. This is because the undulation M ′ (FIG. 5) described above is likely to occur due to the delay in the start of injection, and the air layer is trapped in the molten metal M (FIG. 5).
It is presumed to be a tame. The time when the height of the molten metal on the front surface of the plunger tip 14 reaches the peak P (FIG. 3) is also affected by the amount of hot water supplied. Therefore, the change in the molten metal height according to the amount of hot water should be grasped in advance. I need to put it.

[0014]

As described above, according to the die casting method and the injection apparatus of the present invention, the injection is started at an appropriate timing according to the change in the height of the molten metal on the front surface of the plunger chip. It is possible to suppress the phenomenon of swelling of the molten metal in the injection sleeve, achieve the improvement of casting quality without inviting a complicated die, and its great utility value.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an overall structure of a die casting apparatus including an injection apparatus according to the present invention.

FIG. 2 is a schematic diagram showing the implementation status of the die casting method according to the present invention over time.

FIG. 3 is a graph showing injection start timing in the present die casting method.

FIG. 4 is a graph showing the effect of injection start time on the internal defects of a cast product obtained by the present die casting method.

FIG. 5 is a schematic diagram showing the implementation status of a conventional die casting method over time.

[Explanation of symbols]

10 injection device 11 Hot water supply port 12 Exit 13 injection sleeve 14 Plunger tip 15 Drive means 16 Laser displacement sensor (non-contact displacement sensor) 17 Control means 20 mold 23 cavities M molten metal

Claims (3)

[Claims] 1. A die casting method for injecting molten metal supplied into an injection sleeve into a cavity of a mold by advancing a plunger chip, wherein a sensor detects a molten metal surface height of a front surface of the plunger chip after completion of the hot water supply, A die casting method, wherein the plunger tip is advanced based on the detection result. 2. When the height of the molten metal surface in front of the plunger tip reaches a peak and exceeds a reference value set in the previous stage,
The die casting method according to claim 1, wherein the plunger tip is advanced. 3. An injection sleeve having a hot water supply port, and a plunger tip slidably disposed on the injection sleeve,
In a die casting casting injection device having a driving means for driving the plunger tip, a non-contact displacement sensor for detecting the height of the molten metal surface in front of the plunger chip through the hot water supply port is provided, and a signal from the displacement sensor is provided. An injection device for die casting, characterized in that a control means for controlling the operation of the drive means based on the above is provided.