JPH03458A - Method for detecting raising pressure time in die casting machine - Google Patents

Abstract

PURPOSE:To execute detection of time at high accuracy by making a moment when velocity of an injection plunger drops to less than the set velocity a raising pressure time measuring start point and a moment when pressing force of the plunger raises to more than the set pressure a measuring finish point and measuring the time from the measuring start point to the finish point. CONSTITUTION:In the raising pressure time detecting method in die casting machine/at the time of pressurizing by increasing the pressure after completing filling-up of molten metal by injecting the molten metal into cavity in the die with driving of the injection plunger, the velocity of the injection plunger is measured and also the moment when this velocity is reduced and drops to less than the prescribed set velocity VS is detected to make it the measuring start point C for raising pressure time. Successively, the pressing force of the injection plunger is measured and the moment when this pressure raises to more than the prescribed set pressure P1 is detected to make it the measuring finish point E, and the time T from the above measuring start point to the measuring finish point, is measured. By this method, the measuring start point for raising pressure time can be unified irrespective of the conditions of construction and the measuring time can be detected at high accuracy.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a method for detecting pressure increase time of a die-casting machine,
More specifically, the present invention relates to a method for detecting a pressure increase time after completion of filling molten metal.

[Background technology]

In the die casting method, etc., when filling the mold cavity with molten metal, a method is adopted in which the forward speed of the injection plunger is switched from low speed to high speed, and after filling the molten metal, a pressure increasing valve device is operated to increase the pressure.

Therefore, it is important to understand whether the pressurized state is appropriate, to promptly detect abnormalities when they occur, and to issue a prescribed alarm, etc., in order to maintain the molding characteristics of the cast product at a constant level and to prevent abnormalities from occurring. This can be said to be extremely important in avoiding the production of a large number of non-defective products.

Therefore, in the process of changing the injection pressure, the applicant compares whether the pressure increase time between two points when the pressure increase pulp device is activated is within the allowable range time,
We have already proposed an injection pressure control device that issues an alarm when the allowable time is exceeded (Public Application No. 1-3).
No. 6232).

According to this, the injection pressure under normal conditions shows a sudden pressure increase after the pressure increase valve device is activated, so the injection pressure is 2 ft! !
There is an advantage that it can be determined whether the pressure increase state is normal or not by comparing the pressure increase time between points with a preset allowable range time.

[Problem to be solved by the invention]

However, in the previously proposed method, the starting point of the pressure increase time measurement point after the pressure increase valve device is activated is defined by the set pressure determined by the piston pressing force of the accumulator as the hydraulic pressure source. There were the following problems.

In other words, when the set pressure is used as the starting point for measuring the pressure increase time, it is impossible to unify the starting point because the setting must be changed each time based on changes in casting conditions, etc. I was.

Further, in this case, for example, an accumulator pressure detection head is required for an accumulator pressure car of 35 kg/c11, and an initial setting of 35 kg/c is required.

Furthermore, when the set pressure, which is the measurement start point, is not detected due to an abnormality in the accumulator, etc., the measurement of the pressure increase time itself is not performed, and a problem arises in that the abnormality cannot be detected.

The present invention has been made in view of the fact that the above-mentioned problem is caused by the fact that the above-mentioned set pressure is used as the starting point for measuring the pressure increase time, and its purpose is to increase the pressure regardless of the casting conditions. An object of the present invention is to provide a method for detecting a boosting time of a die-casting machine, which can unify the starting point of time measurement and can detect the measurement time with high precision.

(Means for Solving the Problems) Therefore, the pressure increase time detection method for a die casting machine according to the present invention is applicable to a die casting machine when injecting molten metal into a mold cavity by driving an injection plunger and increasing the pressure after filling is completed. In the pressure increase time detection method, the speed during the injection plunge is measured, and the moment when the speed is decelerated and falls below a predetermined set speed is detected as the starting point for measuring the pressure increase time. The present invention is characterized in that the pressing force is measured, the moment when the pressure rises above a predetermined set pressure is detected as the measurement end point, and the time from the measurement start point to the measurement end point is measured.

[Effect]

According to the method of the present invention, when filling of the molten metal is completed, the speed of the injection plunger is rapidly decelerated, and when the speed falls below the set speed, measurement of the pressure increase time is started. This measurement is terminated when it is detected that the pressing force of the injection plunger exceeds a preset pressure.

Therefore, since the moving speed of the injection plunger at the time of completion of filling is inevitably accompanied by a rapid deceleration, if a specific point during this deceleration is defined as the measurement start point, it is possible to always detect an abnormality.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 shows a block diagram of each component for predetermined processing of actual measured values of injection speed and injection pressure of a die-casting machine. In this figure, the injection pressure is detected by an injection pressure detector 10; The container 10 is provided, for example, in a hydraulic circuit of an injection cylinder that presses an injection plunger (not shown). Further, the injection speed is detected by an injection speed detector 11, and the injection speed detector 1
1 is constituted by a known detector provided on a piston cylinder of an injection cylinder (not shown).

The respective outputs of the injection pressure detector 10 and the injection speed detector 11 are provided to a calculation device 12 at the next stage. This arithmetic device 12 is also provided with a setting device 13,
The setting device 13 inputs and sets the speed that defines the measurement start point of the pressure increase time, the pressure value that defines the measurement end point, and the tolerance range for determining whether the measured time is normal.

The arithmetic unit 12 has a timer function that measures the voltage increase time from the measurement start point to the measurement end point, and a function that compares whether the measurement time is within a set allowable time range, and performs the comparison. The results are output to a display device 14 such as a CRT, and an abnormality signal is output to an alarm means 15 when the measured time deviates from an allowable range of time. At this time, it is preferable that the alarm means 15 be an audio one, a lamp lighting display, or the like.

FIG. 2 shows a state in which the changes in the injection speed and injection pressure over time are processed and displayed on a display device such as a CRT, and a solid curve A shows the changes in the injection pressure. , curve B shown by a dotted line shows the injection speed change.

In FIG. 2, the section is the low-speed injection region of the injection plunger. Furthermore, section H indicates a high-speed injection region, and its end point is the time when filling is completed. The moment when the injection speed suddenly decreases to below the speed V is indicated as the zero point as the measurement start point of the pressure increase time. Also, the point where the pressure booster valve device (not shown) starts in response to detecting a drop below the speed vs.
Shown as points. After the pressure booster valve device is activated, the injection pressure increases dramatically, and approximately 80% of the maximum pressure P2 is determined as the measurement end point E of the pressure increase time, and from the 0 point to E.
The measurement time required to reach the point is shown as T. In addition,
Point S in FIG. 2 indicates the starting point of the injection plunger.

In the above configuration, the pressure increase time detection method for the die-casting machine according to this embodiment is carried out as follows.

In the initial setting, the injection speed (2) for detecting the measurement start point C of the pressure increase time and the pressing force of the injection plunger corresponding to the measurement end point are input in advance to the arithmetic unit 12 via the setter 13.

After completing this setting work, the injection plunger is started, its speed is detected by the injection speed detector 11, and the sequential calculation device 1
Output to 2. On the other hand, the injection pressure detector 10 detects pressure changes in the injection cylinder and outputs the detected pressure changes to the arithmetic unit 12 .

At this point, filling is completed and the injection speed is 2. When the instant C is detected when the speed drops sharply and becomes less than the set speed (2), the timer function of the arithmetic unit 12 is activated and the measurement of the boosting time is started. Immediately after this, the pressure booster valve device operates at point M to further increase the pressing force, and when the measurement end point E corresponding to the set pressure is reached, the timer function of the calculation bags W and 12 is stopped and the measurement start point is The boost time T from C to the measurement end point E is calculated.

The arithmetic unit 12 compares whether the boost time T calculated in this way falls within the preset allowable time range. If the comparison result is within the allowable range of time, no particular abnormality signal is output; however, if the comparison result is outside the allowable range of time, an abnormality signal is output to the next stage alarm means 15, which activates a predetermined buzzer or the like. The operator is notified of any abnormalities.

Note that the injection pressure and injection speed change curves are displayed on the display device 14 in a manner as shown in FIG.

According to this embodiment, the injection speed suddenly drops when filling is completed, without using the set pressure value determined by the piston pressing force of the Akiemulator as in the conventional method as the starting point for measuring the pressure increase time. Since the specific point at the time of measurement is used, it is possible to solve the conventional problem of changing the settings each time based on changes in casting conditions, etc., and it is also possible to unify the measurement starting point, and to keep it constant. This has the advantage of being able to perform measurements with an accuracy of . Moreover, the Achiemulator pressure detection head as described above can also be eliminated.

In addition, since the injection speed is always accompanied by a sudden drop when filling is completed, the measurement disclosure condition is inevitably met, so
Abnormality detection can be performed at all times, and the boost time can be detected with high precision.

In addition, in the above embodiment, as a condition for generating an abnormal signal, the measurement of the boost time is ended at the moment when the measurement end point E is exceeded, and the measured time obtained thereby is compared with the allowable range time. However, if the set pressure, which is the measurement end point, is still not detected even after the maximum allowable range moment has been exceeded after the start of measurement, an abnormality signal may be immediately output to generate an alarm.

When configured in this way, an added effect is that an abnormality can be detected even if a desired pressure increase is not obtained.

Further, the set pressure at the measurement end point is not limited to 80% of the maximum pressure, but may be lower or higher than that.

DESCRIPTION OF SYMBOLS 10... Injection pressure detector, 11... Injection speed detector, 12... Arithmetic device, 13... Setting device, 15...
Alarm means.

Claims (1)

[Claims] (1) In a pressure increase time detection method for a die casting machine when molten metal is injected into a mold cavity by driving an injection plunger and the pressure is increased after filling is completed, the speed of the injection plunger is measured and the speed is decelerated. The moment when the pressure drops below a predetermined set speed is detected and used as the starting point for measuring the pressure increase time.Then, the pressing force of the injection plunger is measured and the moment when the pressure rises above the predetermined set pressure is detected and measured. A method for detecting a pressure increase time for a die-casting machine, characterized in that the time from the measurement start point to the measurement end point is measured, with the measurement start point being the end point.