JP2792580B2 - Pressure stroke control method in pressure casting - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for injecting molten metal into a cavity of a mold by an injection device and pressing the molten metal in the mold by a pressure device having a pressure plunger to obtain a cast product. Pressing stroke control in pressure casting, in which when the pressurizing operation of the pressurizing device is controlled by computer control, the quality judgment of the cast product and the abnormality judgment of the casting process are performed by the 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 molten metal injected into a mold by a pressure device having a pressure plunger is pressurized by pressurization. Injection and flow of cooling water into the pressurized plunger while applying pressure, to provide a cooling effect from the center side of the molten metal, thereby realizing a pressurized casting method that prevents the occurrence of nests due to runoff inside the workpiece. Casters are already well known. Further, in a pressure casting machine having 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 moving stroke of the pressurizing plunger of the pressing device is reduced. Based on the time from the start of operation of the plunger,
The target trajectory is set over time using a computer, and feedback control is performed so as to follow the target trajectory.

[0003] In the above casting machines, for example, as shown in FIG. 4, the maximum stroke value T _P of the target locus T _O, i.e., with respect to the molten metal pressurizing plunger cavity of the mold apparatus It is the most protruding position, and its value T _P
Is set in advance, and the maximum stroke value C of the trajectory Ta of the actual stroke amount is detected as shown by the dotted line, and is compared with the upper and lower limit values A and B. Thus, the quality of the pressure cast product is determined. That is, if the lower limit value B is not reached, the pressurizing stroke of the pressurizing plunger cannot provide a required feeder effect to the molten metal in the cavity, or a coolant is introduced into the plunger to mold the mold. Even if an attempt is made to provide the required cooling effect to the molten metal part away from the surface via a pressure plunger,
In the case where a sufficient cooling effect cannot be given due to the insufficient plunger plunging amount, it is judged that a cast product lacking in density or having burrs is generated. In addition, the upper limit A
When the pressure exceeds the value, the projecting amount of the pressurized plunger against the molten metal in the cavity of the mold device becomes large, and the biscuit part generated in the lower mold of the mold device is cut and separated from the cast part, which hinders the product removal process. Is determined to occur.

[0004]

However, in the conventional pressurizing stroke control method described above, for example, when the amount of hot water supplied is small, the effect of raising the molten metal in the mold cavity is not sufficiently performed. Even in this case, if the pressurizing plunger stroke control is performed within a certain allowable width, the quality is maintained and it is determined that the product is good. An important point in quality control is that the pressurizing plunger operates by a predetermined amount of contraction. From the viewpoint of improving the product yield in the pressure casting, it has been demanded 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. Accordingly, an object of the present invention is to provide a method for controlling a stroke of a pressurized plunger which can satisfy the above-mentioned demands.

[0005]

SUMMARY OF THE INVENTION According to the present invention, in a pressure casting method using a pressure casting machine, feedback control is performed so that a stroke amount of a pressure plunger follows a target trajectory, and a predetermined determination section is set. In this case, the moving average value of the preset number of samplings of the metal pressure of the pressurized plunger is compared with a predetermined lower limit value, and the quality of the pressurized casting is determined in accordance with the upper and lower limits with respect to the lower limit value.

[0006]

As described above, according to the present invention, in controlling the stroke amount of the pressurizing plunger, it follows the target trajectory indicating the time-dependent stroke amount into the mold cavity of the pressurizing plunger. In addition to performing feedback control of the pressurizing plunger stroke, a moving average value of a predetermined moving average number of times of the metal pressure of the pressurizing plunger is compared with a predetermined lower limit value within a predetermined determination section. The quality of the pressed casting is determined according to the upper and lower limits with respect to the lower limit. If the value is lower than the lower limit, it is determined to be non-defective. If the value is lower than the lower limit, it is determined to be defective, and an alarm signal or a correction signal is generated by, for example, turning on 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 performing a pressure stroke control method of a pressure casting method according to the present invention. The mold 10 includes an upper mold 12 and a lower mold 14 that can be opened and closed relatively vertically, and a core 16 that opens and closes from the side with respect to the vertical opening and closing axis of the upper mold 12 and the lower mold 14.
Are provided. Of course, FIG. 1 shows a state in which the mold apparatus 10 is clamped by a mold clamping mechanism (not shown). These upper mold 12, lower mold 14, core 1
6, a cavity 18 as a casting space is formed.
The injection plunger 1 of the injection device 13 is
As the plunger tip 1 and the plunger tip 11 a rise, the molten metal 20 previously supplied into the injection sleeve 15 is injected to fill the cavity 18. The supply of the molten metal to the injection device 13 is generally provided such that, when the injection device 13 is at the position retracted downward, the injection device 13 is further inclined to the side at the retracted position, and is supplied into the injection sleeve 15 by the molten metal supply machine. Have been.

The upper die 12 faces the injection plunger 11.
A pressurizing plunger 17 of a pressurizing device is slidably disposed at an upper portion of the pressurizing device and can protrude into the cavity 18. The pressure plunger 17 is connected to a piston 8c of a pressure cylinder 8 mounted on a movable plate (not shown). The tip 25 of the pressurizing 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 protrude to a position where it starts to enter the central hole 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 inside of 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, the operation of the rod chamber 8b is operated. When the oil is released to the tank 19 via the oil passage 21b, the piston 8c moves forward, and the distal end portion 25 of the pressurizing plunger 17 projects into the cavity 18 of the mold device 10 as shown. Conversely, if the solenoid SOL-b of the directional control valve 7 is excited, the piston 8
c rises, and the distal end portion 25 of the pressurizing plunger 17 returns from the cavity 18 so as to be housed in the upper mold 12.

The pressure of the hydraulic pressure source 6 is controlled by an electromagnetic relief valve 5 comprising an electromagnetic proportional automatic pressure valve. That is, the pressure relief from the hydraulic pressure source 6 is controlled in accordance with the magnitude of the electric signal input to the electromagnetic relief valve 5, so that the protrusion pressure of the pressurizing plunger 17 can be controlled. The stroke position or the stroke amount when the piston 8c of the pressurizing cylinder 8, ie, the pressurizing plunger 17 projects or retreats with respect to the cavity 18, is configured to be detectable by a position detector 9 composed of, for example, a potentiometer. An electric signal can be output according to the position.

On the other hand, a pressure plunger control means 22 comprising computer means such as a microcomputer or a personal computer is provided, and this 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, Receiving the deviation output signals of the deviation operation unit 2 and the deviation operation unit 2 for transmitting the deviation output signals corresponding to the deviation values of these two input signals, an appropriate gain operation process is performed, and a predetermined gain operation corresponding to the deviation output signal is performed. And a PID control operation setting unit 3 for outputting an output signal of the computer. The input means 23 comprises a mouse, for example, a memory such as a ROM and a RAM, the display means 24 comprises a CRT, and arithmetic means such as a microprocessor MPU and a CPU. The command signal setting unit 1, the deviation calculation unit 2, the PID control calculation setting unit 3
Constitutes a feedback controller for the pressurizing cylinder 8 that activates the pressurizing plunger 17. Therefore,
The output of the PID control calculation setting section 3 is sent to an electromagnetic relief valve 5 which forms a pressure regulating valve via a driver 4 and 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.

[0011] In the pressure plunger stroke control as described above, the hydraulic pressure P of the hydraulic pressure P _H and the rod side 8b of the head-side 8a of the piston 8c of the pressure cylinder 8 in FIG. 1
_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].

[0012]

(Equation 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. A certain time t in the determination section obtained from the preset times T ₁ and T ₂
The moving average value M _Ati of the metal pressure of _i can be calculated by [Equation 2], where H is a predetermined number of moving averages.

[0014]

(Equation 2)

FIG. 3 is a time-metal pressure moving average curve for explaining the present invention calculated as described above. FIG.
In, it has set up metal pressure lower limit value M _L advance, in the judgment interval between T ₁ preset determination start time determination end time T _2, the metal pressure moving average value M _Ati and the metal pressure lower limit value M comparing the _L, performs quality determination of the pressure casting article according to the vertical relative to the metal pressure lower limit value M _L. When the metal pressure moving average value M _Atn is below the metal pressure lower limit value M _L, it is judged that the pressure plunger 17 could not give a predetermined feeder effect, for example, the display of the pressure plunger control means 22 The means 24 or an alarm lamp (not shown) may be turned on to emit an alarm signal or a correction signal. On the other hand, when the value is lower than the lower limit value, it is determined that a predetermined feeder effect can be provided, and it is determined that a normal casting has been processed in the casting process, and a good display signal is generated.

[0016] In the present embodiment, when the metal pressure moving average value M _Atn is below once metal pressure lower limit value M _L, but so as to give an alarm command or correction instruction, which is set in advance The alarm command or the correction command may be issued for the first time when the number of times falls below the preset number or continuously falls below the preset number.

[0017]

As described above, according to the present invention, feedback control of the pressurizing plunger stroke amount is performed, and a predetermined moving average of the metal pressure of the pressurizing plunger is set within a predetermined judgment section. By comparing the moving average value of the number of times with a preset lower limit value and judging the quality of the pressure cast product according to the upper and lower limits with respect to the lower limit value, the quality of the pressure cast product can be managed from the aspect of the action of the feeder effect. 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 the drawings]

FIG. 1 is a mechanical diagram showing one embodiment of a mold apparatus and a pressurizing apparatus system for implementing a method of the present invention.

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

FIG. 3 is a time-metal pressure moving average curve for explaining a pressurizing 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 Melt 22 Pressurizing plunger control means 26a, 26b Pressure detector

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B22D 17/22 B22D 17/32 B29C 45/57 B29C 45/76

Claims (1)

(57) [Claims] In a pressure casting in which a molten metal is filled into a mold by the action of an injection device and a molten metal in the mold is pressed by advancing a pressure plunger of a pressure device facing the injection device. The feedback control of the forward movement stroke of the pressurizing plunger is performed so as to follow the target trajectory indicating the amount of time-dependent stroke of the pressurizing plunger into the mold cavity, and the pressurizing plunger is controlled within a predetermined determination section. A moving average value of a predetermined number of moving averages of a metal pressure is compared with a predetermined lower limit value, and the quality of the press-formed product is judged according to the lower limit value. Pressure stroke control method.