JPH0729236B2 - Cam signal processing device in press machine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a cam signal processing device in a press machine that extracts a cam signal corresponding to a slide position of the press machine by an absolute rotary encoder, and particularly detects an error in the cam signal. And a device for generating an emergency stop signal to the press machine.

[Prior Art] Since a press machine needs to synchronize circuits inside the press and machines outside the press in accordance with the position of the slide, it is necessary to accurately detect the current position of the slide. Conventionally, as a means for obtaining a signal corresponding to the position of the slide, there has been one in which a rotary cam switch is arranged on a slide shaft for driving the slide and a signal corresponding to the position of the slide, that is, a cam signal is obtained from the rotary cam switch. . However, a device using such a rotary cam switch has a problem in detection accuracy.Therefore, an absolute type optical rotary encoder is installed on the slide shaft, and a signal that accurately corresponds to the slide position is output from this absolute type optical rotary encoder. (In this specification, this is called a cam signal.) Has been developed.

As shown in the schematic view of FIG. 5, the slide 1 of the press machine is connected to a crank type slide shaft 3 via a connecting rod 2, and as shown in FIG.
The position of changes according to the rotational position of the slide shaft 3. The radius of the crank part of the slide shaft 3 is R
Then, the stroke length of slide 1 is 2R. Therefore, if a 360-division absolute type optical rotary encoder is provided on the slide shaft 3, the position of the slide can be accurately known from the output of the rotary encoder.

[Problems to be Solved by the Invention] 9 By the way, when a cam signal is generated using the absolute type optical rotary encoder as described above, the slit on the code board is optically detected and the electric signal is detected. Although the cam signal is obtained by converting to, the noise may be added to the electric signal to cause an error in the output of the encoder. In this case, the function of the press or the machine synchronized with the press may malfunction, which is extremely dangerous. Therefore, it is necessary to reliably detect an error in the output of the encoder, that is, the cam signal, and to generate an emergency stop signal to the press machine when an error occurs in the output of the encoder.

The present invention has been made in view of the above points, and reliably detects an error in the cam signal formed based on the output of the encoder, and when an error occurs in the cam signal, an emergency stop is promptly made to the press machine. An object is to provide a cam signal processing device in a press machine capable of generating a signal.

[Means for Solving the Problems] The cam signal processing device in the press machine according to the present invention is sufficient to switch the output of the absolute type rotary encoder that detects the slide position of the press machine when the output of the encoder changes. Taking in means for taking in the output value of the encoder after a lapse of a predetermined time, and taking the output value of the encoder at the drive start point of the slide as an initial value, and corresponding to the change every time the taking in value of the taking means changes. Counting means for incrementing or decrementing the count value by unit value is compared with the take-in value of the taking-in means and the count value of the counting means, and when both values match, the take-in value of the taking-in means is used as the cam signal. It is provided with a comparison means for outputting an emergency stop signal to the press machine in case of disagreement.

[Operation] According to the cam signal processing device in the press machine of the present invention, the output value of the encoder taken in by the taking-in means is always compared with the count value of the counting means which is increased or decreased by a unit value in the comparison means, If there is an error in the output value of the encoder taken in by the take-in means, a non-coincidence output will be generated in the comparison result in the above-mentioned comparison means, and an emergency stop signal for the press machine will be generated based on this non-coincidence output.

[Embodiment] An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows a schematic configuration of one embodiment of the present invention.
An encoder shaft 51 of an absolute rotary encoder 5 is connected to a slide shaft 3 (see FIG. 5) of the press machine via a coupling 4. The output of the encoder 5 is applied to the signal processing circuit 7 via the encoder output signal cable 6. The signal processing circuit 7 generates a cam signal corresponding to the slide position of the press machine based on the output of the encoder 6, and an emergency stop signal for the press machine in response to error detection of the encoder output.

FIG. 2 shows the details of the configuration of the encoder 5. The encoder shaft 51 connected to the slide shaft 3 of the press machine via the coupling 4 has a cord board.
52 is installed. A large number of slits are formed in the coder board 52, and the slits represent the rotational position of the code board 52 in the form of a gray code of a plurality of bits. One of the code plates 52 is provided with a plurality of light emitting elements 53 corresponding to the slits of the code plate 52, that is, each bit of the gray code, and the other of the code plates 52 is
A light receiving element 54 for receiving the light from the light emitting element 53 that has passed through the slit of 52 is provided corresponding to each light emitting element, that is, corresponding to each bit of the gray code on the code board. With this configuration, a signal corresponding to the rotational position of the encoder shaft 51, that is, the rotational position of the slide shaft 3 (slide position of the press machine) can be obtained from the light receiving element 54 in the form of a gray code of a plurality of bits.
The output of the light receiving element 54 is applied to the waveform shaping circuit 55, and after being subjected to waveform shaping, applied to the BCD code conversion circuit 56 and converted into a BCD code. The output of the BCD code conversion circuit 56 is output as an encoder output via an output transistor 57 provided corresponding to each bit of the BCD code.

FIG. 3 shows the details of the signal processing circuit 7. The encoder output signal input through the encoder output signal cable 6 shown in FIG. 1 is added to the latch circuit 71 and the counter 72. The counter 72 is composed of a presettable up / down counter, and a signal C / B OFF which becomes high level when the clutch brake of the press machine is off is added to the preset control input PE. Therefore, when the clutch brake of the press machine is off and the slide of the press machine is stopped, the encoder output signal is taken into the counter 72 as it is, and the count value of the counter 72 is the same as the value indicated by the encoder output signal. Has become. The output value B of the counter 72 is compared with the value A indicated by the encoder output signal by the comparator 73. However, since A = B here, no output is produced from the comparator 73.

When the clutch brake of the press machine is turned on and the slide of the press starts to move, the signal C / B OFF applied to the preset control input PE of the counter 72 becomes low level, and eventually the counter 72 moves the slide of the press machine. The encoder output value at the time of starting will be preset.

When the slide of the press machine moves and the encoder output value A changes, B ≠ A is established in the comparator 73, and the comparator 73
Produces a mismatch output. This mismatch output is generated by timer 74
Is added to the clock input CK of the latch circuit 71 after being delayed for a predetermined time. Here, the delay time of the timer 74 is set to be slightly longer than the maximum time required for switching the encoder output signal. The latch circuit 71 takes in the encoder output signal, that is, the encoder output value, in synchronization with the output from the timer circuit 74 applied to the clock input CK.

The encoder output value C fetched by the latch circuit 71 is compared with the output value B of the counter 72 in the comparator 75. If B <C in this comparison, a signal U is output from the comparator 75, and this signal U is the up / down control input U / of the counter 72.
It is added to D, sets the counter 72 in the up mode, and is added to the one-shot circuit 77 via the OR circuit 76. The output of the one-shot circuit 77 is added to the clock input CK of the counter 72. This causes the counter 72 to count up by 1. When B> C is satisfied in the comparator 75, the comparator 75 outputs the signal D, and this signal is applied to the one-shot circuit 77 via the OR circuit 76. Since the signal U is not generated in this state, the counter 72 is set to the down mode, so the counter 72 counts down by one.

In this way, the count value of the counter 72 is incremented or decremented by 1 in correspondence with the increase or decrease of the value taken in by the latch circuit 71.

Further, the value fetched by the latch circuit 71 is added to the comparator 79 via an appropriate delay circuit 78, and the comparator 79 counts the counter.
Compared to 72 output values. Here, the delay circuit 78 is a comparator 75
The count value of the counter 72 is set to be slightly longer than the time required to count up or down by 1 in correspondence with the comparison result in (1).

When B = C is satisfied in the comparator 79, the comparator 79 latches.
It is judged that the encoder output value taken in by 71 is normal and a signal N is output, and this signal N is added to the clock input CK of the latch circuit 80. As a result, the encoder output value taken in by the latch circuit 71 is transferred to the latch circuit 80, and the output of the latch circuit 80 is subjected to required data conversion by the data conversion circuit 81 and output as a cam signal.

When B ≠ C is satisfied in the comparator 79, the encoder output value taken in by the latch 71 is judged to be abnormal, and the comparator 79
Outputs an emergency stop signal to the press machine. When the output value B of the counter 72 reaches a value corresponding to 360 °, this is detected by the 360 ° determination circuit 82, and this 360 ° determination circuit
The output of 82 is applied to the clear input CL of the counter 72, which clears the count value of the counter 72.

Although the case where the signal processing circuit 7 is configured by using the discrete circuit is shown in the above-described embodiment, it may be configured by using the microcomputer.

FIG. 4 shows a processing flow when the signal processing circuit 7 is configured by using a microcomputer. Fourth
In the figure, first, press machine clutch brake signal C /
It is determined whether B is off (step 701). If it is determined that the clutch / brake signal C / B is off, the input encoder output value A is stored as the value B in the first register (not shown) (step 702). Therefore, the stored value B of the first register is equal to the encoder output value A while the clutch / brake signal C / B is off, that is, while the slide of the press machine is stopped. Next, the value B stored in the first register and the encoder output value A are compared, and it is determined whether or not B ≠ A (step 703). Since B = A as described above, the condition of B ≠ A is not satisfied and the step 701 is executed again.
Return to.

When the clutch brake signal is turned on to start driving the slide of the press machine, this is detected in step 701, and the process proceeds to step 703. If B ≠ A holds, a timer (not shown) is started (step 70).
Four). Here, the timer time of the timer is set to be slightly longer than the maximum time required for switching the encoder output value. Subsequently, it is determined whether or not the timer has counted up (step 705), and if it is determined that the timer has counted up, the encoder output value is stored as a value C in a second register (not shown) (step 706). Then, the stored value C of the second register and the stored value B of the first register
And B <C are determined (step 707). If it is determined that B <C, 1 is added to the stored value of the first register, and this added value is set as the new stored value B of the second register (step 70).
8). If B <C is not satisfied, 1 is subtracted from the value stored in the first register, and the subtracted value is set as the new stored value B in the first register (step 709). Subsequently, the value B stored in the first register and the value C stored in the second register are compared with each other to determine whether B = C (step 710). If B = C, it is assumed that the encoder output value C stored in the second register is normal, and the value C is subjected to desired data conversion to form a cam signal (step 711). Output (Step 7
12).

However, if it is determined in step 710 that B = C is not satisfied, the encoder output value C stored in the second register is determined to be abnormal and an emergency stop signal is output.

In the embodiment using the microcomputer, the timer (not shown) can use any timer function inside the microcomputer, and the first and second registers can use any register inside the microcomputer. You can

As described above, according to the present invention, each time the output value of the encoder changes, the output value of the encoder is compared with a value that increases or decreases by a unit value to obtain a cam signal. Since it is configured to judge whether the captured encoder output value is normal or abnormal, an accurate cam signal can be formed and an emergency stop signal can be immediately issued to the press machine when the captured encoder output value is abnormal. ,
It is important to contribute to ensuring the safety of the press machine.

[Brief description of drawings]

1 is a schematic configuration diagram showing an embodiment of the present invention, FIG. 2 is a detailed configuration diagram of an encoder in the embodiment shown in FIG. 1, and FIG. 3 is a detail of a signal processing circuit shown in FIG. FIG. 4 is a flow chart showing the processing flow when the signal processing circuit is constituted by a microcomputer, FIG. 5 is a schematic diagram showing the relationship between the slide of the press and the slide shaft, and FIG. 6 is the slide and encoder output. 2 is a schematic diagram showing a relationship with. 1 ... slide, 2 ... connecting rod, 3 ... slide shaft, 5 ... encoder, 7 ... signal processing circuit.

Claims (1)

[Claims] 1. An absolute encoder, which is connected to a slide shaft of a press machine and whose output value changes at a predetermined unit angle, is provided with a cam signal corresponding to the slide angle of the press machine based on the output of the absolute encoder. In a cam signal processing device in a press machine to be obtained, a detecting means for detecting a change in the output of the absolute encoder, and a change in the output of the absolute encoder is detected by the detecting means, and then the output value of the absolute encoder is completely cut. A latch circuit that latches the output value of the absolute encoder after a lapse of a sufficient time to switch and outputs the latch output as the cam signal, and the output value of the absolute encoder at the drive start point of the slide of the press machine is an initial value. And then before Each time the output of the latch circuit changes, the counting means that increases or decreases the count value by the predetermined unit angle in accordance with the direction of the change is compared with the count value of the counting means and the output of the latch circuit. A cam signal processing device in a press machine, comprising: an abnormality detecting means for detecting an output abnormality of the absolute encoder.