JPS5881600A - Detection of abnormal load in press machine - Google Patents

Abstract

PURPOSE:To detect an abnormal load value and to prevent failure of dies in the stage of pressing with a press machine by measuring press load at every prescribed change in the stroke of a pressurizing mechanism and comparing the same with the preset normal load value. CONSTITUTION:In the stage of pressing a metallic blank material to an intended shape by means of dies with a pressurizing mechanism constituted of a rod which is moved upward and downward by the rotation of the crank shaft of a press machine, the press load of the pressurizing mechanism is measured at every prescribed change in the stroke of said mechanism. The measured value and the preset value changing with each stroke is compared and when it is detected that the measured value is an abnormal value larger than the set value, the driving of the press machine is stopped automatically, whereby the accelerated wear of the dies owing to exertion of abnormal load thereupon and the reduction in the service life of the dies are prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for detecting abnormal load in a press machine.

This type of conventional abnormal load detection method is based on the maximum load l value P for unloading in one stroke of the press illustrated in Fig. 1.
This method detects abnormalities by determining whether the maximum load PM is larger than a preset limit value or full, and detects foreign objects caught in the mold, mold wear, and inappropriateness. It was impossible to detect abnormal changes in the press load caused by the use of workpiece materials, such as the abnormal load changes shown by the dashed line (,) in the figure (b). Even if an abnormality is detected using the above method and all stop signals are sent to the press, the stop of the press will be delayed due to inertia, and a load exceeding the above limit will be applied to the press, causing damage to the mold, etc. There is a risk of damaging it.

Note that the curve (c) shown in FIG. 1 shows the change in press load during normal operation.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method that can overcome the drawbacks of the conventional abnormality detection methods described above.

Therefore, in the present invention, the press load of the press machine is measured every time the pressurizing mechanism of the press machine changes a predetermined stroke, and the normal load corresponding to the preset value of each side is measured. Abnormalities in each of the above measured values are detected by comparing the measured values.

In the present invention, each of the above-mentioned measured values is compared with the maximum allowable load value corresponding to each preset side value, and each of the above-mentioned i! It is designed to detect abnormal sounds of 11 bar values.

Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.

FIG. 3 is a complete block diagram of an example of a device for carrying out the abnormality detection method according to the present invention.

When the rod 2 descends from the top dead center due to the rotation of the crankshaft 1 of the press machine shown in the figure, the crank angle indicating the position of the rod 2 changes to the angle/digital converter 4 (hereinafter referred to as
It is converted into a digital value by an S/D converter (S/D converter). Also, each time the crank □ shaft 1 rotates Δθ, for example, by 1°, the S/D
The converter 4 outputs an increment signal, and this increment signal is input as an interrupt signal to the central processing unit 7 via a differentiator 5p and an interrupt control circuit 6.

On the other hand, the signal outputted from the strain cage 8 is processed as a press load signal by an amplification calculator 9, and converted into an r total value by an A/D converter 10. Ru.

In this example, the press machine has a crankshaft 10 rotation angle (hereinafter referred to as press rotation angle) of 45 degrees.
It is set so that when the angle is in the range of ~180°, the angle is 1γ.

The central processing unit 7 (hereinafter referred to as C1) performs an interrupt process according to the flowchart shown in FIG. 5 every time an interrupt is generated by the output signal of the interrupt control circuit 6.
Execute all.

That is, when the crankshaft 1 is rotated υ1 from the total dead center with the load check switch S1 set to the "on" side and the mode selection switch S2 set to the "continuous" side, the interrupt control is activated. The press rotation angle θX at the time of the 4G VC name interrupt when the interrupt signal is output from the circuit 6 is input to the CPU via the input interface ll'.
7, and then it is determined whether their rotation angles θX are in the range of 45° and θx < 180° or old. When the press rotation angle θX reaches 45°, the CPU 7 switches to the interface 11? The measured value tx of the load at this angle of 45° (hereinafter referred to as press load value) is stored in the random access memory 12 (
Hereinafter, it is stored in R, AMc+: lit.

As shown in FIG. 4, the RAM 12 has an angle of 45 degrees.

Load measurement values tX corresponding to each press rotation angle of 46°, . 136 normal load values Txk corresponding to each normal value storage area M stored in advance
2 and the same maximum allowable load value storage area M3 (in which 136 maximum allowable loads N1 direct T'max corresponding to each of the above-mentioned press load values are stored in advance) are provided.

The operation for storing each normal load value Txk will be described later. Further, each of the above maximum allowable #r plate areas Tmax is shown in FIG. It is set based on the curve (,) shown in Figure 2, and its settings and 112 million operations are determined by the specifications in (5). If this is applied to the press, the press will be damaged.

As described above, when the press load value tx (45°) at a press rotation angle of 45° is stored in the RAM 12, the normal load value TX (45°) stored in the normal value storage area M2 of the RAM 12 is read out, and then the press load value tx (
The values 'ru and TL indicating the allowable deviation width of 45°) are input to the CPU 7 from the setting switch S3+84 via the switch input interface 13. Thus, the CPU 7 performs the operation J1 such that Tux ``'' Tx +Tu 'I'r, x = 'rx 'rL, and executes the following determination.

'rux≧tx≧TLX・・・・・・・・・(
1) And the press load value tx (45°) is given by the above formula (1)
If the meeting is not satisfied, the CPU 7 outputs a warning signal and an emergency stop signal, and these signals are sent to the alarm 1 through the output interface (6), the interface 14, and the signal driver 15.
6 and the press control panel 17, respectively.

As a result, the alarm 16 issues an alarm signal, and the clutch and brake of the press are turned off and turned on, respectively, to stop the press.

On the other hand, if the relationship shown in equation (1) above is satisfied, θX
(45°) Maximum allowable load value Tmax (45°)
) is read out from the storage area M3 of the RAM 12, and then the CPU 7 makes a determination as shown in the following equation.

tX<Tm&e・・・・・・・・・・・・・・・
(2) If this formula (2) is not completely satisfied, the CPU 7 outputs an alarm signal and an emergency stop signal to stop the press machine in the same manner as described above.

In the above, the abnormality detection function of the device when the press rotation angle θX is 45 degrees has been explained, but the rotation angle θX is 180 degrees.
The same abnormality detection as described above is carried out every 10 steps until the press is reached, and if a condition that does not satisfy the above equations (1) and (2) occurs during that time, the press is immediately stopped. However, from then on, the crankshaft 1 of the press machine became 36 mm.
Every time the press rotates by 0°, a load check is performed at each press rotation angle from θX=45° to 180°.

Note that the press rotation angle θX is 181° to 360° to 44°.
In the range of °, the press machine works 4! Therefore, as shown in the flowchart of FIG. 5, the CPU 7 does not input press load data in this range. Also, the above R
Each storage area Ml of AM12.

Each data stored in M2 and M3 is transferred to the CRT controller 18 in the manner shown in FIGS.
The graph is displayed on the RT monitor 19, and therefore the above CR
It is also possible to check for abnormalities in the press from the T-monitor screen.

By the way, there may be cases where you want to keep all the load data obtained during the above-mentioned pre-Z in the RAM 12.
In that case, the switch 5zTh'''f may be switched to the f side. When the switch 82 is switched, the press load data p tx before the time when the switch 82 is switched is stored in the measured value storage area M1'' of the RAM 12.

If you want to check only the press load in a given press stroke, you can switch the switch Sz'r to the "single" side. In other words, when the previous press stroke is finished, switch the switch S2 to the "single" side. When the changeover is made and the switch 86 is pressed, the first interrupt is issued to the CPU 7 and at the same time the load data in the measured value storage area Ml is reset, and as shown in the flowchart in FIG. 5, the load data in the RAM 12 shown in FIG. Single activation flag inside
IF s-# is set. Therefore, from now on, the program will be executed in the same manner as when the switch 82 is turned to the "continuous" side, which means that the press rotation angle θX is 2700.
This continues until the flag +IF8# is reset. You can check only the press load at the current press stroke by sniffing.

Next, the normal value load iTX and the maximum allowable load value Tmax'li? are stored in the RAM 12? The storing operation will be explained with reference to the flowchart shown in FIG. First, in order to store the above normal load value TX k, open the switch Ss k, and set the switch 5zk (9) to the "continuous" side or the "single shot" side, and operate the press machine for only one press step to perform press processing. As a result, the press load value tx for each press rotation angle θX (45° to 180 degrees) is stored in the measured value storage area M1 of the secondary RAM 12,
The evaluation of χ is based on the quality of the product, 1: Ute, or the above CR
The display data on the T monitor 19 is displayed.

If the above load value tx is confirmed to be correct,
As shown in FIG. 6, the switch 5ITh"+;rJ"
fttl, press the switch 87i to transfer each data tx in the measured value storage area M1 to the required location in the normal value storage area M2, and use this as the normal load 11 value TX for the press process to be performed thereafter. do.

On the other hand, the maximum allowable load value Tmax is stored in the RAM 12 using the key switch S8.

That is, after the switch 89 is turned to the 6-on position, the keys of the switches S and F are operated in the following order.

1 pile - 1 ± - 10 - 1 house - circle - [center 1-1 se → 1 This makes the press rotation angle θX the maximum (10) at 45°. The allowable load 'rmaX is 10 to
n, so next, operate the keys of switch S8 in the order of 4 keys - IV draw country - 1 stop low day to find the maximum allowable load when the press rotation angle θX is 50°? [120 ton2 is stored in a predetermined location in the above-mentioned factory M3.

However, when the above-mentioned switch S8 is operated in the order of key e Q → masah, the maximum permissible load values TmhX at the press rotation angle θX of 46° to 49° are calculated by all CPUs 7 through linear interpolation, and these values are It is stored in the storage area M3. Then, by performing key operations in a similar manner, the maximum allowable load value 'rmaxi for all press rotation angles θx (45° to 180°) is stored. Of course, it is also possible to store all the maximum allowable load values TmaX' for each press rotation angle θX from 45° to 180° by key operation of the switch S8, without performing all the above interpolation calculations.

N': When the above storage operation is completed, turn the switch Sek to the "off" side.

In the above embodiment, the pressurizing stroke of the press machine is obtained from the rotation angle of the crankshaft 1, but a sensor (for example, a potentiometer) is provided to detect the linear movement distance of the press slide 20 shown in FIG. The entire pressurizing stroke may be measured from the output signal of this sensor.

In the above embodiment, the entire press load value is detected every time the press 1!1 turning angle θX changes in the JO step, but the step angle can be changed as appropriate depending on the mode of the press.

As described above, in the abnormal charge detection method according to the present invention, the press load in the press machine is detected and checked every time the pressurizing mechanism of the press machine changes a predetermined stroke. Accurately detects abnormal carts caused by wear, entrapment of foreign objects, use of unsuitable workpiece materials, etc., as well as abnormal load conditions as illustrated in curves (a) and (b) in Figure 1. be able to.

Furthermore, if it is assumed that an excessive load as shown by the dashed line curve (d) in FIG. The problem associated with the detection delay of conventional methods can be resolved.

Further, according to the method of the present invention, the life of the mold can be managed by appropriately setting the allowable error TU + TL k of the measured load value with respect to the normal load value.

In other words, when the die wears out and the difference between the normal load value and the measured load value becomes larger than the error 'r,, l'rL, an abnormality in the press load due to die wear is detected. Ru.

[Brief explanation of drawings]

Figures 1 and 2 are graphs illustrating how the 7° recess load and maximum allowable load change with changes in press stroke, respectively, and Figure 3 is a graph for implementing the abnormal load detection method according to the present invention. Block diagram showing an example of the device, No. 4
Figure 5 is a conceptual diagram showing the storage area of the random access memory, Figure 5 is a flowchart for operating the central processing unit of the device shown in Figure 3, and Figure 6 is shown in Figure 3. 1' shows an example of a flowchart for storing all data in a random access memory. 1... Crankshaft, 2... Rod, 3...
Synchro, 4... Synchro/digital converter, 6...
- Interrupt control circuit, 7... Central processing unit, 8... Strangerge, 9... Amplification computing unit, 10... A/D
Converter, 11... Input interface, 12...
Rantime access e-memory, 17...Press control panel, 16...Shipping information 5.5s-8s...Switch, 1
9...CRT monitor. (14) (l-11&+Rotamato'f()7"handle≦)K 1\Δθ package 11 Rise Kasumi B enters IN Fig. 5 No. 5JON ES η Ia152 Rotation of the tower θX input OFF Odd 55 ON ONNO 45\ +1 and η YES (
Fs=1 txN force OFg''=/ fzXexctTE slot 1;
o) Tuxg'rx-fTu ” TLx=Tx-TL ES Mito 1 + NO Figure 6

Claims (2)

[Claims] (1) Measure the press load of the press machine every time the pressurizing mechanism of the press machine changes a predetermined stroke, and compare these measured values with the normal load value corresponding to the valley side constant value set in advance. A method for detecting an abnormal load in a press machine, the method comprising detecting an abnormality in each of the above measured values by comparing them. (2) Press load of the press machine The pressurizing mechanism of the press machine measures each time the DT foot stroke changes, and calculates the maximum capacity load value corresponding to the measured value and the preset valley side constant value. A method for detecting an abnormal load in a press machine, characterized in that an abnormality in the valley side constant value is detected by comparing the values.