JPH03275264A - Method for detecting gnawing of pressurizing plunger in pressurize casting machine - Google Patents

Abstract

PURPOSE:To eliminate insufficient feeder head and cooling by comparing the target locus with the actual locus with the lapse of time respect to stroke quantity of a pressurizing plunger into cavity in a die and detecting the development of gnawing to the plunger from discrimination of interval of the necessary time. CONSTITUTION:Molten metal 26 is filled up into the cavity 18 in the die 10 with an injection device 20. The pressurizing plunger 30 pressurizes the molten metal 26 according to the target locus set in a program. The pressurizing plunger 30 is moved to return back after pressurizing and the total time required for retreating to the starting position of the work is added up and the result is compared with the total time TA of the pre-known target locus. In the case of being TB>TA, it is decided that the pressurizing plunger 30 develops the gnawing and in the case of being TB<=TA, it is decided that the gnawing is not developed. The development of defective product caused by insufficient feeder head and cooling, etc., in the pressurizing process can be prevented.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention involves injecting molten metal into a cavity of a mold using an injection device, and pressurizing the molten metal in the mold using a pressurizing device having a pressurizing plunger. Regarding improvements in pressure casting machines such as guy cast machines and injection mold machines that produce cast products using computer control, in particular, when feedback control of the pressure work by the pressure plunger of the pressure device described above is performed using computer control, automatic The present invention relates to a method for detecting galling of a pressurizing plunger in a pressurizing casting machine, in which galling of the pressurizing plunger can be detected to warn of an abnormality in the machine body or the pressurizing plunger.

[Prior art]

The molten metal is injected into the cavity of the mold device by an injection plunger of the injection device, and the molten metal injected into the mold is applied with a pressurizing effect by pressurization using a pressurizing device having a pressurizing plunger. Pressure casting machines are already well-known, which achieve a pressure casting method in which cooling water flows into and passes through a pressure plunger to cool the molten metal from the center, thereby preventing the formation of cavities due to sinking inside the workpiece. It is.

Furthermore, in a casting machine having an injection device for injecting molten metal into a mold and a pressurizing device for pressurizing the molten metal injected into the mold,
Using a computer, the movement stroke of the pressurizing plunger of the pressurizing device is set as a target trajectory over time based on the time from when the plunger starts operating, and is controlled to follow the target trajectory, thereby applying pressure. A pressure casting machine and its control method, in which the movement stroke of the pressure plunger is optimized and casting accuracy is improved, have already been filed by the applicant in a patent application filed in 1983.
It is proposed as No.-244552.

On the other hand, in a Guy Cast machine, in the process of injecting the molten metal from the injection sleeve of the injection device supplied with the molten metal into the cavity of the mold device by the injection plunger, by detecting galling of the tip of the injection plunger,
A method for preventing gas entrainment and a drop in molten metal temperature due to the waving action of the injection plunger tip in the molten metal injection process is disclosed, for example, in Japanese Patent Publication No. 60-26 by the present applicant.
This method is disclosed in Japanese Patent No. 626 and the like. In this known method for detecting galling of a plunger tip, pressure changes in the injection plunger are constantly detected by a pressure detector, the differential value of the detected pressure change is determined by a differentiator, and compared with a set value by a comparator circuit, the plunger tip is A detection method is disclosed that detects the degree of galling of a chip and issues an alarm if necessary.

[Problem to be solved by the invention]

However, in order to detect galling in the plunger tip of the injection device that injects molten metal as described above, it is necessary to newly install individual hard circuit means such as a pressure detector, a differentiator, and a comparator in the pressure casting machine. 3) There are important and complex issues. In addition, as mentioned above, the pressurizing plunger that gives a feeder effect to the molten metal injected into the cavity of the mold device has an operating speed that is 2 to 3 m/sec higher than the operating speed of the injection plunger. Although it is not publicly known, recently there has been an increase in the use of feedback control methods using personal computers, etc., as the speed is quite slow, about 0.5 to 1 (m/sec). It is coming. Therefore, there is a need to develop a method for detecting galling in a pressurizing plunger of a pressurizing device by effectively utilizing computer means.

[Means to solve the problem]

The present invention sets the operation amount or stroke amount of the pressure plunger in a pressure casting machine in advance as a target locus over time from the operation start time in a pressure plunger control means configured by a personal computer or a microcomputer. The actual stroke amount of the pressurizing plunger is feedback-controlled so as to follow the target trajectory, and the actual stroke amount is determined by comparing the elapsed time required to execute the target trajectory with the elapsed time required to execute the actual stroke amount trajectory. If the time required to complete the stroke trajectory is longer than that of the target trajectory, it is determined that smooth stroke operation could not be achieved due to galling between the pressurizing plunger's pressurizing action and return action. This was confirmed experimentally using a pressure casting machine, and galling was detected.

That is, according to the present invention, the molten metal in the mold is pressurized by filling the mold with molten metal by the action of the injection device, and at the same time, the pressurizing plunger of the pressurizing device facing the injection device is made to make a protruding stroke to pressurize the molten metal in the mold. In a method for detecting galling of a pressurizing plunger in a casting machine, the stroke amount of the pressurizing plunger protruding into the mold cavity and returning is set in advance as a target temporal locus from the start of operation of the pressurizing plunger, and the above-mentioned Feedpack control is performed via the drive circuit of the pressurizing device to control the actual amount of pressure that the pressure plunger pressurizes in accordance with the target temporal locus, and the By comparing the trajectory of the stroke amount over time and determining the magnitude of the time required for the former target trajectory over time and the time required for the actual trajectory over time, the presence or absence of protrusion of the pressurizing plunger or galling in the backward movement is detected. The present invention provides a method for detecting galling of a pressurizing plunger in a pressurizing casting machine.

In fact, when the time of the actual trajectory of the pressure plunger over time is longer than the required time of the target trajectory, the galling detection alarm signal is generated.

In addition, the time of the actual temporal trajectory of the pressurizing plunger is
The number of times greater than the required interval of the above target trajectory is the predetermined number of times,
It may also be possible to issue an alarm signal for galling detection when this occurs continuously.

Alternatively, when the time of the actual temporal trajectory of the pressurizing plunger is longer than the required time of the target trajectory and the time difference is a predetermined amount]2, an alarm signal for galling detection may be issued.

[Effect]

As mentioned above, in the pressure casting process, the stroke amount from the start time of the pressure plunger is determined to determine whether the time required to perform the target temporal trajectory and the time required for the latter actual temporal trajectory are large or small. If the latter is larger than the former for more than a predetermined period of time, or if a phenomenon in which the latter becomes larger repeatedly occurs, the pressure plunger penetrates the mold device and fills the cavity in the same mold. A pressurized plunger control means provided by the computer detects galling as it protrudes into the molten metal and retreats, and an alarm can be issued in response to this detection. In addition, in the present invention, galling is detected in parallel when the pressure plunger is feedback-controlled by the pressure plunger control means provided from the computer to control the stroke amount over time of the plunger. The ejecting and retracting operations of the injection plunger in the low speed range and high speed range are set in advance with a target trajectory (7) (8) and controlled to follow the target trajectory using a control means also comprised of a computer. Needless to say, it is also possible to detect galling in the operation of the injection plunger or its tip in the same manner as described above. Hereinafter, the present invention will be explained in more detail based on embodiments shown in the accompanying drawings.

〔Example〕

FIG. 1 is a graph illustrating the principle of the method for detecting galling of a pressure plunger according to the present invention, and FIG. 2 shows the configuration of the main parts of a pressure casting machine to which the method for detecting galling according to the present invention is applied. The block diagram shown in FIG. 3 is a flowchart for issuing an alarm using the counter function of the pressurizing plunger control means.

First, referring to FIG. 2, the mold device 10 includes an upper mold 12 and a lower mold 14 that can be opened and closed relative to each other vertically, and a side with respect to the vertical opening/closing axis of the upper mold 12 and the lower mold 14. It is configured to include a core 16 that opens and closes from both sides. Of course, FIG. 2 shows a state in which the mold device 10 is clamped by a mold clamping mechanism (not shown). A cavity 18, which is a casting space, is formed by these upper mold 12, lower mold 14, and core 16, and in the cavity 18, as the injection plunger 22 and plunger tip 22a of the injection device 20 rise, the inside of the injection sleeve 22a is formed. The molten metal 26 supplied in advance is injected and fills the cavity 18. The molten metal is generally supplied to the injection device 20 by a configuration in which when the injection device 20 is in a downwardly retracted position, the molten metal is further tilted to the side in the retracted position and is supplied into the injection sleeve 22a by a molten metal feeder. It is being

Opposed to the injection plunger 22, a pressurizing plunger 30 of a pressurizing device is disposed in the upper part of the upper mold 12 so as to be slidable and projectable into the cavity 18. This pressure plunger 30 is connected to a piston 28c of a pressure cylinder 28 attached to a movable platen (not shown).

The tip of the pressurizing plunger 30 is provided so as to be able to protrude to the gate seal position of the mold cavity 18, that is, the position where it starts to penetrate into the central hole opening of the lower mold 14. The operation of the pressurized cylinder 28 is started by supplying pressure oil from a hydraulic source 34 to the cylinder chamber 28a or 28b via the directional control valve 36. At this time, the return oil returns into the tank 38. That is, the solenoid 5QL-A of the directional control valve 36 is energized, and the pressure oil of the hydraulic source 34 is supplied to one head chamber 2 of the pressurizing cylinder 28 via the oil passage 42a.
8a, and at the same time, the hydraulic oil in the rod chamber 28b is introduced into the oil passage 2.
8b and into the tank 38, the piston 28c moves forward and the tip of the pressurizing plunger 30 protrudes into the cavity 18 of the mold device 10 as shown in the figure. Conversely, if the solenoid SQL-8 of the directional control valve 36 is energized, the piston 28c of the pressurizing cylinder 28
rises, and the tip of the pressurizing plunger 30 enters the cavity 1.
8 to be housed in the upper mold 12.

The pressure of the hydraulic power source 34 is configured to be controllable by an electromagnetic relief valve 40 consisting of an electromagnetic proportional automatic pressure valve. In other words, the pressure relief from the hydraulic pressure source 34 can be controlled in accordance with the magnitude of the input electric signal to the electromagnetic IJ valve 40, thereby controlling the protrusion pressure of the pressurizing plunger 30. Now, the piston 28c1 of the pressurizing cylinder 28
In other words, the stroke position or stroke amount when the pressurizing plunger 30 protrudes or retreats from the cavity 18 is determined by the position detector 3 made of, for example, a potentiometer.
2 so that it can be detected and output an electrical signal depending on its position.

On the other hand, there is provided a pressurizing plunger control means 50 consisting of computer means such as a microcomputer or a personal computer.
Mold cavity 18 of pressurized plunger 30 against time
The target trajectory T shows changes in stroke amount due to inward protrusion over time. A command signal setting section 52 that can be set, and a manual signal that is a detection signal of the position detector 32 and a command signal setting section 5.
A deviation calculation unit 54 compares and calculates the command human power signals from the input signals from the input signals 2 and sends out a deviation output signal corresponding to the deviation value of both input signals, and receives the deviation output signal of the deviation calculation unit 54 and calculates an appropriate gain. The command signal setting section 52 includes a gain setting section 56 that performs processing and outputs a predetermined output signal according to the deviation output signal (11) and (12) above, and the command signal setting section 52 is an input means consisting of a computer keyboard or a mouse. 62 and memory (for example, ROM and RAM), on the other hand, the deviation calculation section 54 and the gain setting section 5
6 is formed by arithmetic means such as a microprocessor MPU and a CPU. Then, the command signal setting section 5
2. The deviation calculating section 54 and the gain setting section 56 constitute a feedback controller for the pressurizing cylinder 28 that starts the pressurizing plunger 30. Therefore, the gain setting section 56
The output is sent to the driver 58 of the electromagnetic relief valve 40, which controls the pressure regulating valve, via means (not shown). That is, the driver 58 creates a valve driving electric signal corresponding to the magnitude of the output signal from the gain setting section 56 and sends it to the electromagnetic IJ valve 40. Therefore, the pressurizing cylinder 28 is feedback-controlled by the feedback controller, the electromagnetic relief valve 40, and the direction switching valve 36, and the stroke amount of the pressurizing plunger 30 is adjusted to the target trajectory So.
control to follow.

Now, as shown in FIG. 2, when the filling of the molten metal by the injection plunger 20 is completed, the host controller (not shown) gives an operation command for the pressurizing plunger 30 to the pressurizing plunger control means 50 at predetermined time intervals, and Solenoid 5QL-8 of directional control valve 36 is energized. The command signal setting unit 52 of the pressurizing plunger control means 50 stores in advance a desired trajectory of the stroke amount St of the pressurizing plunger 30 with respect to time t from the start of plunger operation, as the above-mentioned target trajectory S. The stroke amount S of the target trajectory So is set in the program when the above-mentioned operation command is received.
t is time-divisionally processed every few milliseconds, and the deviation calculation unit 5
Enter 4. In the same deviation calculating section 54, the position detector 32
The deviation ΔSt (-3t-3t) from the actual stroke position St" of the pressurizing plunger 30 detected at is calculated and inputted to the gain setting section 56. Gain setting section 5
6 is a control amount for the stroke amount deviation amount ΔSt, which is obtained by multiplying a predetermined gain (gain), for example, P (proportional) I (integral) D (differential) gain, based on the result of the deviation ΔSt. Convert to pressure command value Pc.

The above PID gain is set as an empirical value.

When the pressure command value Pc is input, the driver 58 converts it into a signal Prf that actually drives the electromagnetic relief valve 40,
The pressure of the hydraulic power source 34 is controlled, and the hydraulic pressure to the pressurizing cylinder 28 is controlled via the directional switching valve 36. In this way, the target trajectory S in the stroke amount of the pressurizing plunger 30. By controlling the pressure for operating the pressurizing cylinder 28 based on the deviation between the actual stroke amount Sa and the actual stroke amount Sa, the actual stroke amount of the pressurizing plunger 30 is feedback-controlled. A stable feeder effect at the required level is always given to the molten metal 26 to obtain a cast product that is dense and of good quality without any internal shrinkage cavities. Further, a more detailed explanation of the feedback control of the pressurizing plunger 30 mentioned above has already been disclosed in Japanese Patent Application No. 63244552 filed by the present applicant. Actually, the target trajectory S is set in the command signal setting section 52. is C connected to the pressurizing plunger control means 50.
The settings can be made simply by displaying a menu on a display device 60 such as an RT and drawing a graph of the vertical axis stroke St and the horizontal axis time t using an input means 62 such as a mouse.

Now, as mentioned above, the target trajectory S. In the process of setting and controlling the stroke amount of the pressurizing plunger 30 using the feedback control method, the actual temporal trajectory S8 of the stroke amount executed by the pressurizing plunger 30 is the target trajectory S. However, there are many cases where they do not match. For example, in the process of using the pressurized plunger 30 for a long period of time, the surface of the plunger 30 may be worn out, lubrication may be insufficient, or solidified molten metal particles may be deposited on the surface of the plunger or on the mold device 10 on which the plunger 30 slides. Galling may occur during the stroke of the pressurizing plunger 30 due to adhesion to the hole surface or the like or due to vibration transmission from the outside.

Such galling causes fluctuations in the molten metal feeding action by the pressurized plunger, or causes waving of the molten metal (15) and (16) entrainment of regas, leading to quality deterioration of pressure cast products. Become.

Therefore, in the present invention, when such galling occurs,
As shown in FIG. 1, the target trajectory S of the pressurizing plunger 30 described above. When comparing the total time TA required to complete the actual time course Sa and the total time TB required to complete the actual time course Sa, the latter total time TB required to complete the actual time course Sa is due to the plunger speed reduction due to galling. , which focuses on the fact that the TA of the former is larger than that of the former.

That is, the pressurizing plunger 30 returns after pressurizing the molten metal in the mold device 10, and the total time TB until the pressurizing plunger 30 returns to the operation start position is measured and integrated, and the target trajectory S, which is known in advance, is calculated.
. The following comparison operation with the total time TA is performed.

TB>TA ・・・・・・ (1) Ta2 TA
(2) If the formula (1) holds true, it is detected that the pressurizing plunger 30 is galling, and a galling occurrence signal is sent out.

Furthermore, when equation (2) holds true, it is detected that no galling has occurred yet, and no galling occurrence signal is transmitted.

Note that the total time TB in the actual temporal trajectory S8 is measured using the timer function of the microprocessor CPU or MPU forming the deviation calculation section 54 in the pressurizing plunger control means 50 shown in FIG. What is necessary is to measure the time from the stroke start time of the pressurizing plunger 30 until it returns to the starting position.

Furthermore, the calculation of the above equation (1) or (2) is performed by the microprocessor MPU or CPU forming the deviation calculation section 54.
It can be easily executed by calculation means such as

Here, in the above-mentioned embodiment, galling of the pressurizing plunger 30 is detected by simply calculating equation (1) or (2), but the result of the galling detection described above is used as shown in FIG. It is stored in the memo IJ-(RAM) forming the command signal setting section 52 of the pressure plunger control means 50, and in the process of repeating the pressure casting process a plurality of times, galling is detected continuously for a predetermined number of times. What was done is the above MPU and C
When it is determined by counting the number of galling detections stored in the memory using the counter function of the computing means such as the PU, an alarm signal is issued from the output section of the computing means, and an appropriate 110 For example, it may be sent as an output signal to prompt lighting of an alarm lamp or the like via means.

FIG. 3 is a flowchart showing the process in which an alarm is issued when such galling is detected multiple times. First, the set value TA and the actual stroke amount value TB are Read and compare the size of both,
When the latter actual stroke amount is large, a counter is counted up, and when the count reaches a predetermined number of times or more, an alarm is issued. Also, if TIl is smaller than TA, then
If it is determined that there is no bite and a count has been made before that, the counter is cleared.

Furthermore, the target temporal trajectory S. The time TA, which indicates a total time larger than the total time TA by a predetermined amount of time, is also stored in advance as a set value, and the time course S of the actual stroke amount is calculated.
First, the total time TIl in a is compared with the above TA, and the total time TB in successive pressure casting processes gradually reaches the target trajectory S. The alarm may be issued only when a certain situation occurs for a time greater than the total time TA, which is longer than the above-mentioned TA.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, the stroke amount of the pressure plunger during the pressurization and feeder stroke is set in advance as a target trajectory, and the actual stroke of the pressure plunger follows this target trajectory. In addition to performing feedback control, the total time of the target trajectory and the actual stroke amount trajectory over time is compared, and an alarm is issued when the total time required for the actual stroke amount trajectory over time is greater than the total time required for the target trajectory. Therefore, the galling detection is automated, and the occurrence of galling can be detected by calculation processing inside the computer means. It is possible to obtain high-quality cast products without cavities or cracks that occur in the cast products due to insufficient hot water, insufficient cooling, or the like.

[Brief explanation of drawings]

FIG. 1 is a graph illustrating the principle of the method for detecting galling of a pressure plunger according to the present invention, and FIG. 2 shows the configuration of the main parts of a pressure casting machine to which the method for detecting galling according to the present invention is applied. FIG. 3 is a flowchart for issuing an alarm using the counter function of the pressurizing plunger control means. IO...mold device, 18...cavity, 26...
- Molten metal 20...injection device, 22...injection cylinder,
28... Pressure device, 30... Pressure plunger, 32
. . . position detector, 50 . . . pressurizing plunger control means. Diagram

Claims (1)

[Claims] 1. Pressurizing the molten metal in the mold by filling the mold with molten metal by the action of the injection device and by making a protruding stroke of the pressurizing plunger of the pressurizing device facing the injection device. In the method for detecting galling of a pressure plunger in a casting machine, the stroke amount of the pressure plunger protruding into the mold cavity and returning is set in advance as a target temporal locus from the start of operation of the pressure plunger, The actual stroke amount by which the pressurizing plunger pressurizes in accordance with the target temporal locus is feedback-controlled via the drive circuit of the pressurizing device, and the temporal trajectory of the target locus and the actual stroke amount of the pressurizing plunger is determined. The present invention is characterized in that the presence or absence of protrusion of the pressurizing plunger or galling in the retreating operation is detected by comparing the time required for the former target temporal trajectory and the required time for the latter actual temporal trajectory. A method for detecting galling in a pressure plunger in a pressure casting machine.