JPH0798251B2 - Method for detecting galling of pressure plunger in pressure casting machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention is to inject molten metal into a cavity of a mold by an injection device, and pressurize the molten metal in the mold by a pressurizing device having a pressure plunger. For improvement in pressure casting machines such as guy cast machines and injection molding machines to obtain casting products, especially when feedback control of the pressure work by the pressure plunger of the above-mentioned pressure device by computer control is performed automatically. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting galling of a pressure plunger in a pressure casting machine, which can detect galling of the pressure plunger to warn of an abnormality of the machine body or the pressure plunger.

[Prior art]

The molten metal is injected into the cavity of the mold device by the injection plunger of the injection device, while the molten metal injected into the mold by the pressure device having a pressure plunger is applied while pressing the molten metal. A pressure casting machine that realizes a pressure casting method that allows cooling water to flow in and out of the pressure plunger to give a cooling effect to the molten metal from the center side and prevents the formation of cavities due to sink marks inside the workpiece is already known. Is.

Further, in a 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 pressure plunger of the pressure device is set as a target trajectory using a computer over time based on the time from the start of the operation of the plunger, and the target trajectory is controlled to follow the target trajectory. A pressure casting machine and a control method thereof, in which the movement stroke of the pressure plunger is optimized to improve the casting accuracy, have already been filed by the applicant of the present application in Japanese Patent Application No. 63-
Proposed as 244552.

On the other hand, in the guy cast machine, by detecting the galling of the tip of the injection plunger in the step of injecting the molten metal from the injection sleeve of the injection device supplied with the molten metal by the injection plunger into the cavity of the mold device,
A method for preventing gas entrainment and lowering of the molten metal temperature due to the waviness of the injection plunger tip in the molten metal injection process is disclosed in, for example, Japanese Patent Publication No.
It is disclosed in Japanese Patent Publication No. In this known plunger chip galling detection method, the pressure change of the injection plunger is constantly detected by the pressure detector, the differential value of the detected pressure change is obtained by the differentiator, and it is compared with the set value by the comparison circuit to make the plunger A detection method is disclosed in which the degree of chipping of a chip is detected and an alarm is issued if necessary.

[Problems to be solved by the invention]

However, in order to perform the galling detection in the plunger chip of the injection device that performs the above-mentioned molten metal injection, it is necessary to newly provide the pressure casting machine with individual hard circuit means such as a pressure detector, a differentiator, and a comparator. There are complications. Further, as described above, the operating speed of the pressurizing plunger that exerts a feeder effect on the molten metal injected into the cavity of the mold device is 2 to the operating speed of the injection plunger.
The speed is much slower than 3 (m / sec) and 0.5 to 1 (m / se
Since it is about c), it is not publicly known, but recently, a method of using a personal computer or the like to feedback-control its operation has been adopted. Therefore, there is a demand for development of a method for detecting galling in a pressure plunger of a pressure device by effectively utilizing computer means.

[Means for Solving the Problems]

In the present invention, the operation amount or stroke amount of the pressure plunger in the pressure casting machine is set in advance as a time-dependent target locus from the operation start time in the control means of the pressure plunger configured by a personal computer or a microcomputer, and this target is set. The actual stroke amount of the pressurizing plunger is feedback-controlled so as to follow the trajectory, and the actual stroke amount is compared by comparing the elapsed time required to perform the target trajectory with the elapsed time required to perform the trajectory of the actual stroke amount. If the time required to execute the trajectory is longer than that of the target trajectory, it can be determined that a smooth stroke operation could not be achieved due to the galling of the pressurizing and pressing operation and the returning operation of the pressurizing plunger. This was done by using a pressure casting machine and confirming it experimentally to detect galling.

That is, according to the present invention, the pressurization for filling the molten metal in the mold by the action of the injection device and for pressing the molten metal in the mold by causing the pressurizing plunger of the pressurizing device facing the injection device to make a protruding stroke. In the galling detection method of the pressure plunger in the casting machine, the stroke amount of the protrusion and the return of the pressure plunger into the mold cavity is preset as a target time course from the operation start time of the pressure plunger, and The actual stroke amount of the pressurizing plunger that follows the target temporal locus is feedback-controlled through the drive circuit of the pressurizing device, and the target temporal locus of the pressure plunger and the actual stroke amount temporal locus are obtained. By comparing the time required for the former target time course and the time required for the latter actual time course, the pressure plunger protrudes or retracts. It is intended to provide a galling detection method of the pressure plunger in the casting machines to detect the presence or absence of galling in.

It should be noted that, in effect, when the time of the actual trajectory of the pressurizing plunger is longer than the time required for the target trajectory, a gall detection warning signal is issued.

Also, the time of the actual time course of the pressure plunger is
When the number of times longer than the required time of the target locus continues for a predetermined number of times, an alarm signal for galling detection may be issued.

Alternatively, when the time of the actual trajectory of the pressurizing plunger is longer than the required time of the target trajectory, a galling detection alarm signal may be issued when the time difference is a predetermined value or more.

[Action]

As described above, regarding the stroke amount from the operation start time of the pressure plunger in the pressure casting process, the size of the time required for performing the target time course and the time required for the latter actual time course is determined, When the latter is larger than the former for a predetermined time or more, or when the latter is repeatedly enlarged many times, the pressure plunger penetrates the mold device and is filled in the cavity in the mold. It is detected by the pressurizing plunger control means composed of a computer that the galling occurs in the process of protruding into the molten metal and retreating, and an alarm can be issued in response to this detection. In the present invention, the pressurizing plunger is controlled by the pressurizing plunger control means including a computer in parallel with the feedback control of the stroke amount of the plunger. When controlling the projecting and retracting operations of the injection plunger to eject in the low speed range and the high speed range by setting the target locus in advance by the control means also composed of a computer and following the target locus so as to follow the target locus, It goes without saying that it is also possible to configure so as to detect galling in the operation of the plunger or its tip. Hereinafter, the present invention will be described in more detail with reference to the embodiments shown in the accompanying drawings.

〔Example〕

FIG. 1 is a graph for explaining the principle of the galling detection method for a pressure plunger according to the present invention, and FIG. 2 shows the configuration of the main part of a pressure casting machine to which the galling detection method according to the present invention is applied. A block diagram and FIG. 3 are flow charts when an alarm is issued by 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 which can be relatively opened and closed relative to each other, and a vertical opening / closing axis of the upper mold 12 and the lower mold 14. And a core 16 that opens and closes from one side. Of course, FIG. 2 shows a state where the mold apparatus 10 is clamped by a mold clamping mechanism (not shown). These upper mold 12, lower mold 1
4, the core 16 forms a cavity 18 which is a casting space, and the molten metal 26 previously supplied into the injection sleeve 22a by the ascent of the injection plunger 22 and the plunger tip 22a of the injection device 20 is formed in the cavity 18. It is injected and fills the same cavity 18. The molten metal is supplied to the injection device 20 when the injection device 20 is at the position retracted downward,
In the retracted position, a structure is generally provided in which the molten metal is supplied to the inside of the injection sleeve 22a by tilting further to the side. A pressure plunger 30 of a pressure device is slidably disposed on the upper portion of the upper mold 12 so as to face the injection plunger 22 and can protrude into the cavity 18. The pressure plunger 30 is connected to a piston 28c of a pressure cylinder 28 attached to a movable plate (not shown). The tip of the pressure plunger 30 is
It is provided so as to be able to project to the gate seal position, that is, the position where it starts entering the center hole of the lower mold 14. The operation of the pressurizing cylinder 28 is started by supplying the pressure oil supplied from the hydraulic pressure source 34 to the cylinder chamber 28a or 28b via the direction switching valve 36. At this time, the return oil returns to the tank 38. That is, the solenoid SOL-A of the direction switching valve 36 is excited to guide the pressure oil of the hydraulic pressure source 34 to the one head chamber 28a of the pressurizing cylinder 28 via the oil passage 42a, and at the same time, the rod chamber 2
When the hydraulic oil of 8b is released to the tank 38 via the oil passage 28b, the piston 28c moves forward, and the tip end portion of the pressure plunger 30 projects into the cavity 18 of the mold apparatus 10 as shown. On the contrary, when the solenoid SOL-B of the direction switching valve 36 is excited, the piston 28c of the pressurizing cylinder 28 rises in the opposite manner to the above, and the tip of the pressurizing plunger 30 moves from the cavity 18 into the upper mold 12. It returns and operates so that it is stored. The pressure of the hydraulic pressure source 34 is configured to be controlled by an electromagnetic relief valve 40 which is an electromagnetic proportional automatic pressure valve. That is, the hydraulic pressure source is changed according to the magnitude of the electric signal input to the electromagnetic relief valve 40.
Control the pressure relief from 34, and thus pressurizing plunger 30
It is possible to control the projecting pressure of. Now, pressurizing cylinder
28 piston 28c, that is, the stroke position when the pressure plunger 30 projects or retracts with respect to the cavity 18,
Alternatively, the stroke amount can be detected by the position forming device 32 including, for example, a potentiometer, and an electric signal can be output according to the position.

On the other hand, a pressure plunger control means including computer means such as a microcomputer and a personal computer
The pressure plunger control means 50 is provided with a command signal setting unit 52 that can set a change in the stroke amount due to the protrusion of the pressure plunger 30 into the mold cavity 18 with respect to time as the target trajectory T ₀ with time. A deviation calculator that compares and calculates an input signal, which is a detection signal of the position detector 32, and a command input signal from the command signal setting unit 52, and outputs a deviation output signal corresponding to the deviation value of both of these input signals. 54, and a gain setting unit 56 that receives the deviation output signal of the deviation calculation unit 54, performs appropriate gain calculation processing, and outputs a predetermined output signal according to the deviation output signal, and the command signal setting unit 52 Is
Input means consisting of computer keyboard and mouse 62
And a memory (for example, a ROM and a RAM), while the deviation calculator 54 and the gain setting unit 56 are formed by a calculator such as a microprocessor MPU or a CPU. Then, the command signal setting unit 52, the deviation calculation unit
The gain setting unit 54 and the gain setting unit 56 constitute a feedback controller for the pressure cylinder 28 that activates the pressure plunger 30. Therefore, the output of the gain setting unit 56 is an electromagnetic relief valve 4 that forms a pressure regulating valve via I / O means (not shown).
0 to the driver 58. That is, the driver 58 creates a valve driving electric signal corresponding to the magnitude of the output signal from the gain setting unit 56 and sends it to the electromagnetic relief 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 controlled by the target locus S _0.
Control to follow.

Now, as shown in FIG. 2, when the filling of the molten metal by the injection plunger 20 is completed, a host controller (not shown) gives an operation command of the pressure plunger 30 to the pressure plunger control means 50 at a predetermined time interval. Direction switching valve
Energize 36 solenoid SOL-A. In the command signal setting unit 52 of the pressurizing plunger control means 50, a desired locus of the stroke amount St of the pressurizing plunger 30 with respect to the time t from the start of the plunger operation is programmed in advance as the target locus S ₀ described above. Therefore, when the above-described operation command is received, the stroke amount St of the target locus S ₀ is time-divisionally processed, for example, every few milliseconds, and is input to the deviation calculator 54. The deviation calculating unit 54 calculates a deviation ΔSt (= St−St ′) from the actual stroke position St ′ of the pressure plunger 30 detected by the position detector 32, and inputs this to the gain setting unit 56. . Gain setting section
The reference numeral 56 multiplies a predetermined gain (gain), for example, P (proportional) I (integral) D (derivative) gain based on the result of the deviation ΔSt, and the pressure is a control amount for the deviation amount ΔSt of the stroke amount. Convert to command value Pc. The PID gain is set as an empirical value. When the pressure command value Pc is input, the driver 58 receives the signal Pr that actually drives the electromagnetic relief valve 40.
It is converted into f, the pressure of the hydraulic pressure source 34 is controlled, and the hydraulic pressure to the pressurizing cylinder 28 is controlled via the direction switching valve 36.
In this way, by controlling the pressure for operating the pressurizing cylinder 28 on the basis of the deviation between the target locus S ₀ in the stroke amount of the pressurizing plunger 30 and the actual stroke amount S _a , The actual stroke amount is feedback-controlled, and as a result, the pressurizing plunger 30 constantly gives the molten metal 26 a required level of stable feeder effect, so that a dense and good-quality cast product with no shrinkage cavities inside can be obtained. I have to. A more detailed description of the above-mentioned feedback control of the pressure plunger 30 has already been disclosed in Japanese Patent Application No. 63-244552 filed by the present applicant. Actually, the target locus S ₀ set in the command signal setting unit 52 is displayed as a menu on the display device 60 such as a CRT connected to the pressure plunger control means 50, and the vertical axis is set by the input means 62 such as a mouse. It can be set only by drawing a graph of the stroke St and the horizontal axis time t.

Now, in the process of setting the target locus S ₀ as described above and controlling the stroke amount of the pressurizing plunger 30 by the feedback control method, the actual temporal locus S _a of the stroke amount executed by the pressurizing plunger 30 is the target. Feedback control is performed so as to match the trajectory S ₀ , but there are many cases where they do not match.
For example, in the process of using the pressure plunger 30 for a long period of time, the surface wear and poor lubrication of the plunger 30, or the solidified molten particles may cause the plunger surface and the plunger 30 to come out.
In some cases, galling may occur in the stroke stroke of the pressure plunger 30 due to attachment to the surface of the hole of the sliding mold apparatus 10 or due to transmission of vibration from the outside.
Such galling may cause fluctuations in the molten metal feeder action by the pressure plunger, or may cause gas entrainment or the like due to the corrugation of the molten metal, resulting in deterioration of the quality of the pressure cast product.

Therefore, the present invention, when such galling occurs,
As shown in FIG. 1, when the total time T _A for executing the target locus S ₀ of the pressurizing plunger 30 and the total time T _B required for executing the actual temporal locus S _a are compared, It is focused on that the total time T _B required to execute the actual time-course locus S _a of is larger than the former T _A due to the speed reduction of the plunger due to the galling.

That is, the pressurizing plunger 30 pressurizes the molten metal of the mold apparatus 10 and then returns to operate, and totalizes the total time T _B until it retracts to the operation start position, and totalizes the total time of the target trajectory S ₀ known in advance. The following comparison calculation with T _A is performed.

T _B ＞ T _A …… (1) T _B ≦ T _A …… (2) And, if the formula (1) is satisfied, it is detected that the pressure plunger 30 is galling, and the galling occurs. The generation signal is sent out.

Further, when the expression (2) is satisfied, it is detected that the galling has not yet occurred, and the galling generation signal is not transmitted.

The measurement of the total time T _{B on} the actual trajectory S _a is performed by the deviation calculation unit in the pressurizing plunger control means 50 shown in FIG.
The timer function of the microprocessor CPU or MPU forming 54 may be used to measure the time from the actual stroke start time of the pressurizing plunger 30 to the returning operation and returning to the starting point position.

Further, the calculation of the formula (1) or the formula (2) can be easily executed by the calculating means such as the microprocessor MPU or the CPU forming the deviation calculating section 54.

Here, in the above-described embodiment, the galling detection of the pressurizing plunger 30 is performed only by performing the calculation of the equation (1) or the equation (2). However, the result of the galling detection described above is shown in FIG. It is stored in the memory (RAM) forming the command signal setting unit 52 of the pressure plunger control means 50, and in the process of repeating the pressure casting process a plurality of times, the galling detection is continuously performed a plurality of predetermined times. However, by counting the number of galling detections stored in the memory by the counter function of the computing means such as the MPU or CPU, when it is determined, an alarm signal is first issued from the output part of the computing means. A signal may be emitted and sent as an output signal for prompting lighting of an alarm lamp or the like via an appropriate I / O means.

FIG. 3 is a flow chart showing the processing when an alarm is issued when such galling detection occurs a plurality of times. First, the set value T _A and the actual stroke amount value T _{B are shown.} When the actual stroke amount of the latter is large, the counter is counted up, and when the count number becomes a predetermined number or more,
Send an alarm. Also, if T _B is smaller than T _A , it is determined that there is no galling, and if the count is performed before that, the counter is cleared.

Further, the total time T _A of the target time-course locus S ₀ , and a time T _A ′ indicating a total time longer than the target time-course S _{0 by} a predetermined time, is also stored as a preset value, and the total time of the actual stroke amount on the time-course locus S _a is calculated. T _B and performs first a comparison with the T _a, finally increases than the total time T _a of the total time T _B gradually target locus S ₀ in pressure casting process successive, the T _a larger time than T _a The alarm may be issued for the first time when a situation larger than ′ occurs.

〔The invention's effect〕

As is apparent from the above description, according to the present invention, the stroke amount in the pressurization and feeder stroke of the pressurizing plunger is set in advance as the target trajectory, and the actual stroke of the pressurizing plunger follows the target trajectory. In addition to feedback control, the total time of the target trajectory and the actual stroke amount over time is compared, and an alarm is issued when the total required time of the actual stroke amount over time is greater than the total required time of the target trajectory. Therefore, the galling detection is automated, and the occurrence of galling can be detected by the arithmetic processing inside the computer means. As a result, it is possible to obtain a high-quality cast processed product that does not have cavities or cracks in the cast product caused by the above.

[Brief description of drawings]

FIG. 1 is a graph for explaining the principle of the galling detection method for a pressure plunger according to the present invention, and FIG. 2 shows the configuration of the main part of a pressure casting machine to which the galling detection method according to the present invention is applied. FIG. 3 is a flow chart in the case of issuing an alarm using the counter function of the pressure plunger control means. 10 ... Mold device, 18 ... Cavity, 26 ... Molten metal, 20 ... Injection device, 22 ... Injection cylinder, 28 ... Pressurizing device, 30 ... Pressurizing plunger, 32 ... Position detector, 50 ... Pressurizing plunger control means.

Claims (1)

[Claims] 1. A pressure casting machine for filling molten metal in a mold by the action of an injection device and pressing the molten metal in the mold by causing a pressurizing plunger of a pressure device facing the injection device to make a protruding stroke. In the method for detecting the galling of the pressure plunger, the stroke amount of the protrusion and the return of the pressure plunger into the mold cavity is preset as a target time course from the start of the operation of the pressure plunger, and the target time course According to the above, the actual stroke amount of the pressurizing operation of the pressurizing plunger is feedback-controlled via the drive circuit of the pressurizing device, and the target trajectory of the pressurizing plunger and the temporal trajectory of the actual stroke amount are compared. However, based on the size comparison between the time required for the former target time-course and the time required for the latter actual time-course, the pressure plunger can be set to project or retract. A method for detecting galling of a pressure plunger in a pressure casting machine, which is characterized in that the presence or absence of galling is detected.