JPH05146860A - Method for controlling pressurizing stroke in pressurized casting - Google Patents

Abstract

(57) [Summary] [Purpose] The quality of pressure-cast products is judged more accurately. [Structure] The pressure plunger is controlled by time-position, the metal pressure of the pressure plunger is also detected, the moving average of metal pressure is compared with a preset lower limit value, and the pressure cast product is moved up and down with respect to the lower limit value. The pass / fail judgment is made.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is to obtain a cast product by injecting a molten metal into a cavity of a mold by an injection device and pressurizing the molten metal in the mold by a pressure device having a pressure plunger. Regarding pressure casting, particularly when controlling the pressurizing work of the pressurizing device by computer control, the pressurizing stroke control in pressurizing casting in which the quality of the cast product and the abnormality of the casting process are judged by a computer It is about the method.

[0002]

2. Description of the Related Art A molten metal is injected into a cavity of a mold device by an injection plunger of an injection device, while a pressurizing device having a pressure plunger presses the molten metal injected into the mold by pressing. The pressure casting method realizes a pressure casting method in which cooling water flows in and passes through the pressure plunger to give a cooling effect to the molten metal from the center side and prevents the formation of cavities due to the sink in the workpiece. Casting machines are already known. Further, in a pressure casting machine equipped with an injection device for injecting the molten metal into the mold and a pressurizing device for pressurizing the molten metal injected into the mold, the movement stroke of the pressurizing plunger of the pressurizing device is changed. Based on the time from the start of operation of the plunger,
A computer is used to set a target trajectory over time, and feedback control is performed so that the target trajectory is set.

In the above pressure casting machine, for example, as shown in FIG. 4, the maximum stroke value T _P of the target locus T _O , that is, the pressure plunger is against the molten metal in the cavity of the mold apparatus. The most prominent position and its value T _P
The upper limit value A and the lower limit value B sandwiching the above are set in advance, the maximum stroke value C of the trajectory Ta of the actual stroke amount is detected as shown by the dotted line, and it is compared with the upper and lower limit values A and B. Therefore, the quality of the pressure cast product was judged. That is, when the lower limit value B is not reached, the amount of pressurization stroke of the pressurizing plunger cannot give the required riser effect to the molten metal in the cavity, or the cooling liquid is introduced into the plunger to make the die. Even if an attempt is made to give the required cooling effect to the molten metal part away from the surface via the pressure plunger,
When a sufficient amount of cooling effect cannot be provided due to the insufficient plunge amount of the plunger, it is judged that a cast product with a lack of compactness or cavities will be produced. Also, the upper limit value A
When the pressure exceeds the maximum value, the amount of protrusion of the pressure plunger with respect to the molten metal in the cavity of the mold device becomes large, and the biscuit part formed in the lower mold of the mold device is cut and separated from the cast product part, hindering the product removal process. Is determined to occur.

[0004]

However, in the above-mentioned conventional pressurization stroke control method, the effect of pushing the molten metal in the mold cavity is not sufficient due to, for example, a small amount of hot water supply. Even in such a case, if the pressure plunger stroke control is performed within a certain allowable width, it is determined that the quality is maintained and the product is good. An important point in quality control is that the pressurizing plunger operates for the specified shrinkage amount. From the viewpoint of improving the product yield in the pressure casting process, it is required to improve the stroke amount control of the pressure plunger in the pressure casting so as to correspond to the quality of the cast product. Therefore, the present invention is to provide a stroke control method for a pressure plunger that can satisfy the above-mentioned demands.

[0005]

According to the present invention, in a pressure casting method using a pressure casting machine, feedback control is performed so that the stroke amount of a pressure plunger follows a target locus, and a preset judgment interval is set. In the above, the moving average value of the preset sampling frequency of the metal pressure of the pressurizing plunger is compared with the preset lower limit value, and the quality of the pressure cast product is determined according to the upper and lower sides of the lower limit value.

[0006]

As described above, according to the present invention, when the stroke amount of the pressure plunger is controlled, the preset trajectory of the pressure plunger, which indicates the time stroke amount into the mold cavity, is followed. The feedback control of the pressurizing plunger stroke is performed, and the moving average value of the preset moving average times of the metal pressure of the pressing plunger is compared with the preset lower limit value within the preset judgment section. The quality of the pressure cast product is judged according to the upper and lower limits. When it is below the lower limit, it is judged as a good product, and when it is below the lower limit, it is judged as a defective product, and an alarm signal or a correction signal is issued by lighting an alarm display or an alarm lamp.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a mechanism diagram of a mold apparatus and a pressure casting system for carrying out the pressure stroke control method of the pressure casting method according to the present invention. The mold 10 includes an upper mold 12 and a lower mold 14 which can be relatively opened and closed relative to each other, and a core 16 which is opened and closed laterally with respect to the vertical opening and closing axis of the upper mold 12 and the lower mold 14.
And is configured. Of course, FIG. 1 shows a state where the mold apparatus 10 is clamped by a mold clamping mechanism (not shown). These upper mold 12, lower mold 14, core 1
6, the cavity 18 which is a casting space is formed,
In the cavity 18, the injection plunger 1 of the injection device 13
The molten metal 20 previously supplied into the injection sleeve 15 is injected by the ascent of 1 and the plunger tip 11a to fill the cavity 18. For supplying the molten metal to the injection device 13, when the injection device 13 is in a position retracted downward, the molten metal is supplied to the injection sleeve 15 by a molten metal feeder, and the structure is generally provided. Has been.

The upper mold 12 is opposed to the injection plunger 11.
A pressure plunger 17 of the pressure device is slidably disposed above the upper part of the cavity and is projectable into the cavity 18. The pressure plunger 17 is connected to a piston 8c of a pressure cylinder 8 attached to a movable plate (not shown). The tip 25 of the pressure plunger 17 is located at the gate seal position of the mold cavity 18, that is, the lower mold 1
4 is provided so as to be able to project to a position where it starts entering the central hole opening 18a. The operation of the pressurizing cylinder 8 is started by supplying the pressure oil supplied from the hydraulic pressure source 6 to the cylinder chamber 21a or 21b via the direction switching valve 7.
At this time, the return oil returns to the tank 19. That is, the solenoid SOL-a of the direction switching valve 7 is excited to guide the pressure oil of the hydraulic pressure source 6 to one head chamber 8a of the pressurizing cylinder 8 via the oil passage 21a, and at the same time, to operate the rod chamber 8b. When the oil is released to the tank 19 through the oil passage 21b, the piston 8c advances and the tip 25 of the pressure plunger 17 projects into the cavity 18 of the mold apparatus 10 as shown in the drawing. On the contrary, when the solenoid SOL-b of the direction switching valve 7 is excited, the piston 8 of the pressurizing cylinder 8 is reversed, contrary to the above.
c rises, and the tip portion 25 of the pressure plunger 17 returns so as to be housed in the upper mold 12 from inside the cavity 18.

The pressure of the hydraulic power source 6 can be controlled by the electromagnetic relief valve 5 which is an electromagnetic proportional automatic pressure valve. That is, the pressure relief from the hydraulic pressure source 6 can be controlled according to the magnitude of the input electric signal to the electromagnetic relief valve 5, and thus the protrusion pressure of the pressurizing plunger 17 can be controlled. The stroke position or stroke amount when the piston 8c of the pressurizing cylinder 8, that is, the pressurizing plunger 17 projects or retracts with respect to the cavity 18, can be detected by the position detector 9 including, for example, a potentiometer, An electric signal can be output according to the position.

On the other hand, a pressure plunger control means 22 composed of computer means such as a microcomputer or a personal computer is provided, and the pressure plunger control means 22 projects the pressure plunger 17 into the mold cavity 18 with respect to time. compared over time the command input signal from the target locus T _O set as can command signal setting unit 1, the position detector command signal setting unit 1 and the input signal is a detection signal of 9 changes in stroke volume due to operation, The deviation output signals of the deviation calculation unit 2 and the deviation calculation unit 2 which output the deviation output signals corresponding to the deviation values of both of these input signals are received, appropriate gain calculation processing is performed, and a predetermined value corresponding to the deviation output signal is received. And a PID control calculation setting unit 3 for outputting an output signal of the pressure plunger control means 22. The input means 23 is a computer, memory such as ROM and RAM, display means 24 is a CRT, and arithmetic means such as a microprocessor MPU or CPU. Then, the command signal setting unit 1, the deviation calculation unit 2, the PID control calculation setting unit 3
Constitutes a feedback controller for the pressure cylinder 8 which activates the pressure plunger 17. Therefore,
The output of the PID control calculation setting section 3 is sent to an electromagnetic relief valve 5 which constitutes a pressure adjusting valve via a driver 4 and an I / O means (not shown). Thus, the pressure cylinder 8 is feedback controller and an electromagnetic relief valve 5, is feedback-controlled by a directional control valve 7, the stroke amount of the pressure plunger 17 is controlled so as to follow the target locus T _O.

In the pressure plunger stroke control as described above, the hydraulic pressure P _H on the head side 8a of the piston 8c and the hydraulic pressure P on the rod side 8b of the pressure cylinder 8 of FIG.
_R is measured by the pressure detectors 26a and 26b. Metal pressure M _P at the distal end 25 of the pressure plunger 17, D ₁ the cylinder inner diameter of the pressure cylinder _8, the cylinder rod outer diameter D _2, the tip diameter of the tip portion 25 of the pressure plunger 17 When D _C , [Equation 1] can be used for calculation.

[0012]

[Formula 1]

FIG. 2 is a time-metal pressure curve for explaining the present invention calculated as described above. In FIG.
The sampling interval T _S , the determination start time T ₁ , and the determination end time T ₂ are preset values. Within a judgment section obtained from preset times T ₁ and T ₂ , a certain time t
The moving average value M _Ati of the metal pressure of _i can be calculated by [Equation 2], where H is a preset moving average number.

[0014]

[Formula 2]

FIG. 3 is a time-metal pressure moving average value curve for explaining the present invention calculated as described above. Figure 3
In the above, the metal pressure lower limit value M _L is set in advance, and the metal pressure moving average value M _Ati and the metal pressure lower limit value M are set in the predetermined determination section from the determination start time T ₁ to the determination end time T _{2. L} is compared, and the quality of the pressure cast product is determined according to the upper and lower sides of the metal pressure lower limit value M _L. When the metal pressure moving average value M _Atn falls below the metal pressure lower limit value M _L , it is judged that the pressurizing plunger 17 could not give the predetermined feeder effect, and for example, the display of the pressurizing plunger control means 22 is performed. The means 24 or an alarm lamp (not shown) may be turned on to issue an alarm signal or a correction signal. When the lower limit value is exceeded, it is determined that the predetermined feeder effect can be given, and it is determined in the casting process that a normal cast product has been processed, and a good display signal is issued.

In this embodiment, an alarm command or a correction command is issued when the metal pressure moving average value M _Atn falls below the metal pressure lower limit value M _L once, but this is set in advance. It is also possible to issue an alarm command or a correction command for the first time when the number of times falls below the predetermined number or when the number of times falls below a preset number continuously.

[0017]

As described above, according to the present invention, feedback control of the pressurizing plunger stroke amount is performed, and a preset moving average of the metal pressure of the pressurizing plunger is set within a preset determination section. By comparing the moving average value of the number of times with the preset lower limit value and judging the quality of the pressure cast product according to the upper and lower limits of the lower limit value, the quality of the pressure cast product can be controlled from the aspect of the effect of the feeder. Therefore, there is an effect that a cast product that passes a certain acceptable quality standard can be manufactured with a high yield.

[Brief description of drawings]

FIG. 1 is a mechanism diagram showing one embodiment of a mold device and a pressure device system for carrying out the method of the present invention.

FIG. 2 is a time-metal pressure curve for explaining a pressure stroke control method according to the present invention.

FIG. 3 is a time-metal pressure moving average value curve for explaining a pressing stroke control method according to the present invention.

FIG. 4 is a diagram showing an example of a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Command signal setting part 2 Deviation calculation part 3 PID control calculation setting part 8 Pressurizing device 9 Position detector 10 Mold device 11 Injection plunger 13 Injection device 17 Pressurizing plunger 18 Cavity 20 Molten metal 22 Pressurizing plunger control means 26a, 26b Pressure detector

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location G05D 3/12 D 9179-3H

Claims (1)

[Claims] 1. A pressure casting method for filling molten metal in a mold by the action of an injection device and advancing a pressure plunger of a pressure device facing the injection device to press the molten metal in the mold. Feedback control of the forward movement stroke of the pressurizing plunger is performed so as to follow the target locus indicating the amount of time-dependent stroke of the pressurizing plunger into the mold cavity. A comparison of a moving average value of a preset moving average number of times of metal pressure with a preset lower limit value, and the quality of the pressure cast product is judged according to the upper and lower limits of the lower limit value. Pressure stroke control method.