JP2719308B2 - Top dead center stop control method for press machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a press machine in general, and more particularly to a method for controlling a top dead center (fixed position) stop of a large press machine having an automatic feeder and requiring accurate stop position control. .

[0002]

2. Description of the Related Art Generally, in a press machine using an eccentric shaft or a crankshaft, a clutch for connecting or disconnecting a drive source and an eccentric shaft or a crankshaft, and a brake for tightening or loosening a brake on an eccentric shaft or a crankshaft. The clutch and the brake are controlled by a solenoid valve operated by a start signal or a stop signal from a control device. By the way, conventionally, as such a control method, a method is known which includes several crank angle detection switches corresponding to a rotation stop angle of a press machine, and switches between these switches to perform control. However, this control method can cope with the case where the rotation stop angle of the press machine changes stepwise, but can cope with the case where the rotation stop angle is arbitrary (stepless). Therefore, there is a problem that accurate stop position control to the top dead center cannot be expected.

[0003]

Therefore, the present invention solves the above-mentioned conventional problems and can cope with the case where the rotation stop angle of the press machine changes steplessly. An object of the present invention is to provide a control method capable of controlling a machine to an accurate top dead center stop position.

[0004]

According to a first aspect of the present invention, when a press machine is stopped by a stop signal output at a predetermined rotation stop angle from a control device, a stop signal is output by a stop signal. 1) Activate the solenoid valve to disengage the clutch, calculate the rotational speed of the press machine and the angle difference from the rotation stop angle to the top dead center in advance, calculate the time from this angle difference and calculate the time to set the timer time. The second electromagnetic valve is actuated by the time-up to apply a brake, and the press machine is stopped at the top dead center stop position.

According to a second aspect of the present invention, in the first aspect, when the press machine stops at a position shifted from the top dead center stop position, a shift angle from the top dead center stop position of the shift stop position is obtained by a detector. It is characterized in that an appropriate correction time is calculated and calculated from this deviation angle, added to and subtracted from the timer time, and the time obtained by the addition and subtraction is reset as the correction timer time.

[0006]

As described above, since the control is performed based on the timer time preset in the timer, it is possible to cope with the case where the rotation stop angle of the press machine changes steplessly.

[0007]

FIG. 1 is a block diagram showing a cross section of an eccentric shaft portion of a large press machine and a control system thereof according to an embodiment of the present invention, in which a clutch 2 is provided at one end of an eccentric shaft 1 and the other end thereof. The brake 3 is mounted on the part. The clutch 2 is a solenoid valve 5
When the compressed air is not supplied, the rotation of the flywheel 6 is transmitted to the eccentric shaft 1 via the friction plate 7. The brake 3 releases a brake wheel 9 connected to the eccentric shaft 1 when compressed air is sent by an electromagnetic valve 8. A central processing unit (CPU) 11 of a computer as a control device activates the electromagnetic valve 8 in response to a start signal to send compressed air to the brake 3, and activates the electromagnetic valve 5 after a certain period of time when the brake 3 is loosened to apply the clutch 2 to the clutch 2. The compressed air is sent in, the clutch 2 is connected, and the solenoid valve 5 is actuated by a stop signal to discharge the compressed air from the clutch 2, and the solenoid valve 8 is actuated after a lapse of time when the friction plate 7 is disconnected from the flywheel 6. Then, the compressed air of the brake 3 is discharged to stop. The CPU 11 has a timer Te, a timer Tbr, and a memory R in addition to the calculation unit 12. Reference numeral 13 denotes a rotation angle detector such as a rotary encoder installed on the eccentric shaft 1, and its detection signal is read into the CPU 11 by the actual rotation speed.
This is output as the actual stop angle reading.

FIG. 2 shows the operation of the clutch 2 and the brake 3 in the press machine described above, with the horizontal axis representing time and the vertical axis representing air pressure, and the solid line represents the brake 3 and the dotted line represents the clutch 2. ing. When the air pressure is high (usually 5 kg / cm ² ), the brake 3 is loosened, the clutch 2 is connected and the press machine is operated, and when the air pressure is 0, the brake 3 is applied and the clutch 2 is cut off and the press machine Stops. That is, when the start signal T1 is output from the CPU 11, the electromagnetic valve 8 is operated to feed compressed air, and the brake 3 is loosened. After the lapse of the time of the clutch timer Te from the start signal T1, a clutch operation signal T2 is output, the solenoid valve 5 is operated, compressed air is sent, and the clutch 2
Is connected, and the press machine starts at time T3 without damaging the operation of the clutch 2 and the brake 3. Next, the stop signal T4 is set in advance by the detection signal of the detector 13, and is output based on Table 1 of the rotation speed and the rotation stop angle of the press machine input to the memory R.

[0009]

[Table 1]

The solenoid valve 5 is actuated by the output stop signal T4, the compressed air is discharged from the clutch 2 and the clutch 2 is disengaged. From stop signal T4 to brake timer Tb
After the elapse of the time r, the brake operation signal T5 is output, the electromagnetic valve 8 is operated, the compressed air is discharged, the brake 3 is applied, and the press machine stops.

FIG. 3 shows one stroke of the crankshaft of the press machine with respect to the stop of the press machine as a circle, the inside of which is represented by an angle, and the outside thereof is represented by a time. Based on the input values in Table 1, the angle at which the stop signal is generated is determined by Q (θ ₂ )
And Q (θ ₁ ) at low speed. The time at which the stop angle occurs corresponds to T4 in FIG. Although the brake timers Tbr1 and Tbr2 are shown to have a large angle difference, the actual timer time does not have a large difference as shown in the figure because the rotational speed of the press machine is faster in Q than in R. Will be. The rotating press machine has an angle Q,
When a stop signal is received at the position R, a brake operation signal T5 is output after a lapse of Tbr1 or Tbr2, the brake 3 is applied, and the brake stops at the top dead center P via the mechanical slip angle θs1 or θs2.

Now, as shown in FIG. 4, the press machine receives the stop signal T4 at point R of the angle θ, the clutch 2 is disengaged, the brake 3 is operated after the brake timer Tbr has elapsed, and the press machine passes through the mechanical slip angle θs. It is assumed that the vehicle stops at the point P 'which has passed the dead point P. At this time, a detector 13 which constantly detects the rotation angle of the eccentric shaft 1 detects a deviation angle of the stop angle (correction threshold angle), and the arithmetic unit 12 of the CPU 11 uses the detected deviation angle to rotate the press machine. A learning correction amount Ta, which is a correction time, is calculated by taking the speed into account. Then, when the next press step is stopped, the learning correction amount Ta is subtracted from the timer Tbr (Tbr-Ta). As a result, the deviation angle (correction threshold angle) θa of the next press stop is corrected, and R
The clutch 3 is disengaged at the point, the brake 3 is applied after the timer time Tbr-Ta has elapsed, and the top dead center P
The press machine will stop accurately. As described above, the detector 13 detects the deviation angle (correction threshold angle) θa of the stop angle for each pressing process, and the calculation unit 12 of the CPU 11 calculates the correction time Ta and corrects the time of the brake timer Tbr. Therefore, the stop position of the top dead center P of the press machine is always kept correct. In addition, an allowable range is provided for the deviation angle of the stop angle (correction threshold angle) θa, and when the stop angle of the press machine exceeds the allowable range, an abnormal alarm is issued, so that a mechanical abnormality (an abnormal state) occurs in the clutch / brake. (Wear, malfunction) can be notified to the operator. In the above, when the point P 'is before the top dead center P, the learning correction amount obtained from the shortage time is added to the timer time Tbr, and the press machine is also stopped accurately at the top dead center P in the same manner. Let it.

The embodiment of the present invention is as described above.
FIG. 5 shows the overall control in a flowchart. That is, the ready output is turned on by the power-on start, and the press machine is on standby. When the start signal T1 is output from the CPU 11 to the press machine, the previously set rotation number is read, the brake signal is turned on, the brake 3 is loosened, and the clutch timer Te operates at the same time. When the clutch timer Te elapses, the time is up, the clutch permission input is turned on, the clutch signal T2 is turned on, and one-step operation is confirmed.
Is connected, and the press machine starts.

When the press machine rotates and receives the stop signal T4 at a predetermined rotation stop angle, the ready output is turned off, the standby state of the press machine is released, the clutch signal is turned off, and the compressed air of the clutch 2 is released. The clutch 2 is disengaged and disengaged. Further, the brake signal Tbr is activated by the stop signal T4, and when the time is up, the brake operation signal T5 is turned off, the compressed air of the brake 3 is discharged, the brake 3 is applied, and the press machine stops.
The detector 13 reads the stop angle and detects the stop deviation angle based on the top dead center as a corrected threshold angle, and based on this, the C
The PU 11 calculates the learning correction amount Ta in consideration of the rotation speed, adds and subtracts the learning correction amount Ta to and from the brake timer Tbr, and constantly updates the time of the brake timer Tbr. When the stop deviation angle at the top dead center of the press machine exceeds the allowable range of the corrected threshold angle θa, an overrun is issued to notify an operator that an abnormality has occurred in the clutch / brake.

[0015]

According to the first aspect of the present invention, when the press machine is stopped by the stop signal output from the control device at a predetermined rotation stop angle, the first solenoid valve is operated by the stop signal to operate the clutch. And the angle difference from the rotation speed and the rotation stop angle of the press machine to the top dead center is calculated in advance, the time is calculated from the angle difference, and the timer time set in the timer is increased. Is operated to apply a brake to stop the press machine at the top dead center stop position, so that the press machine can be stopped very accurately at the top dead center. Moreover, it is not necessary to newly provide a timer for the press machine, the apparatus is not complicated, and there is no need to provide a number of crank angle detection switches as in the prior art. In addition, the stop position at the top dead center can be finely controlled in seconds by converting the stop rotation angle into time.

According to a second aspect of the present invention, in the first aspect, when the press machine is stopped with a shift from the top dead center stop position, a shift angle from the top dead center stop position of the shift stop position is determined by a detector. An appropriate correction time is calculated from this deviation angle and calculated and added to and subtracted from the timer time, and the time obtained by the addition and subtraction is reset as the correction timer time, so that the press machine can be operated stably for a long time. The maintenance can be further improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a cross section of an eccentric shaft portion of a large press machine and a control system thereof according to an embodiment of the present invention.

FIG. 2 is a diagram showing the operation of a clutch and a brake of a press machine, with time on the horizontal axis and air pressure on the vertical axis.

FIG. 3 is a drawing showing a configuration related to stopping of the press machine, in which one stroke of a crankshaft of the press machine is indicated by a circle, and the inside is represented by an angle and the outside is represented by a time.

FIG. 4 is a drawing at the time of a correction time according to the embodiment.

FIG. 5 is a control flowchart for explaining the operation.

[Explanation of symbols]

 1 Eccentric shaft 2 Clutch 3 Brake 5, 8 Solenoid valve 11 CPU 12 Operation unit

Claims (2)

(57) [Claims] When the press machine is stopped by a stop signal output from a control device at a predetermined rotation stop angle, the first solenoid valve is operated by the stop signal to disengage the clutch, and the rotational speed of the press machine is previously determined. And the angle difference from the rotation stop angle to the top dead center is calculated, the time is calculated from the angle difference, the second solenoid valve is operated by the time-up of the timer time set in the timer, and the brake is applied. Stopping control at a top dead center stop position of a press machine. 2. When a press machine stops at a position shifted from a top dead center stop position, an angle of deviation from the top dead center stop position of the shift stop position is obtained by a detector, and an appropriate correction time is calculated from the angle of deviation. 2. The top dead center stop control method for a press machine according to claim 1, wherein the time obtained by the addition and subtraction is calculated and added and subtracted, and the time obtained by the addition and subtraction is reset as a correction timer time.