JPH05341824A - Positioning method for nc device - Google Patents

Abstract

PURPOSE:To omit the pre-processing equivalent to a single block and also to ensure the high positioning accuracy by carrying on the linear interpolation after permuting the value of shift extent with the value obtained by subtracting the following shift error produced by an external signal from a prescribed shift extent when the external signal is inputted during the execution of a linear interpolation command. CONSTITUTION:In a 1st step, the extreme value set in the driving direction of a drive axis which performs the positioning is previously defined as the command value of a linear interposition and a stop shift extent is previously set in a range covering the input of an external signal through the stop of the drive axis. In a 2nd step, the remaining shift extent obtained by subtracting the shift extent of the drive axis from the command value of the linear interpolation is monitored. Then the 1st steep is reset when the remaining shift extent is equal to 0 and otherwise a 3rd step is set. In the 3rd step, the 2nd steep is reset when the external signal is not inputted yet. When the external signal is inputted, the shift extent obtained by subtracting the follow-up deviation set with input of the external signal from the stop shift extent is permutated with the remaining shift extent. Then the drive shaft is moved by an extent equal to the permuted remaining shift extent and then stopped.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positioning method in an NC device, and is particularly used in the field of industrial machinery, and is a work feeder (a device for cutting a work into a certain length by a work-carrying conveyor and supplying it to a machine tool). The present invention relates to a positioning method in an NC device which is applied to positioning of the above.

[0002]

2. Description of the Related Art In a conventional positioning method for an NC apparatus, when a predetermined position of a positioning drive shaft is detected by an external signal during positioning and the positioning shaft is moved from the predetermined position by a predetermined amount and then stopped, it is usually NC. The device controls to the predetermined position, and after detecting the predetermined position by an external signal, the device is moved by a predetermined amount by a relay sequence circuit or a PC (programmable controller) and stopped. In this case, the stopping accuracy is insufficient,
In positioning that requires stopping accuracy, it is desirable to continue NC control by the NC device and execute positioning. A specific example of such positioning will be described below.

FIG. 3 is an illustration of a work feeder. In the figure, reference numeral 1 indicates a conveyor, which is driven by a motor (not shown). The work 2 placed on the conveyor 1 moves to the right as shown by the arrow in the figure, and when the tip of the work 2 is detected by the sensor 3 located below the intermediate position between the conveyor 1 and the conveyor 1 ', The detection signal is transmitted to the NC device 4, moves by a predetermined distance, stops, and is cut by a cutter 5 of a cutting machine (not shown). After cutting, the cut work 2'is further moved to the right by the conveyor 1'and conveyed. Further, the work 2 is again moved to the right by the conveyor 1, the same operation as described above is repeated, and the work 2 is cut into a certain length one after another, and the work 2'is conveyed to the right. Next, an NC device for positioning the work feeder, which requires the above-described stop accuracy, will be described.

FIG. 4 is a flow chart of processing of a method for positioning a work feeder according to the prior art. The numbers following S in the figure indicate step numbers. In explaining the figure, an NC program using a skip function for realizing the NC device will be described below. N1 G31 G91X9999.99999 F100
0 N2 G01 X100.0 N3 M10 N4 M99

The skip function is described in the first sequence number N1 of the NC program. This skip function is a movement command following G31, and linear interpolation can be commanded as in the case of G01. When a skip signal is input from the outside during this command, the rest of this command is canceled and the next block is executed. Further, G31 is a one-shot command and is effective only in that block. In this example, since the next block is an incremental command in G91, the next block operates incrementally from the position interrupted by the skip signal. That is, the linear interpolation pre-processing is executed at a feed speed of 1000 mm / min toward the position of 999999.999 mm in the X-axis direction until a skip command is input by the signal of detecting the work 1 of the sensor 3 (step S41). ). That is, the movement amount is calculated from the interpolation command, and further, the movement amount is calculated for each sampling cycle. Next, the pulse execution distribution command is input to the drive control device that drives the X-axis every sampling period of 8 msec (step S42). Next, the skip signal is monitored, and it is determined whether or not the detection signal from the sensor 3 is input to the NC device 4 as the skip signal. If the skip signal does not come, the process returns to step S42, and if the skip signal comes, the step proceeds. The process proceeds to S44 (step S43).

Next, the linear interpolation G0 of the sequence number N2
The preprocessing 1 and the pulse execution distribution are executed, and the movement of 100 mm in the X-axis direction is started (step S44). By this linear interpolation, the desired distance to be moved is moved from the position detected by the sensor 3. The desired distance, here 100 mm
After the movement, the cutter 5 of the cutting machine is operated by the command of M10 having the sequence number N3 (step S45), and the start address of the program is sent by the command of M99 having the sequence number N4.
That is, the process returns to step S41 (step S46), and the same cycle is repeated again.

[0007]

In the positioning method in the NC device according to the prior art described above, the block of the movement command is divided into the above-mentioned two blocks N1 and N2, and the sequence number N2 after the skip command is given between the two blocks. Depending on the system, the time required for pre-processing to be executed is 16 msec-3.
There is a problem that the feed is stopped once for a time of 2 msec, and the cycle time is delayed due to this stop time.
Furthermore, the servo tracking deviation amount remains at the time when an external signal from a sensor or the like is input, but since this deviation amount is not taken into consideration, the feed amount increases by that amount and the operation stops after the external signal is input. There is a problem that the distance to This follow-up deviation amount represents a delay amount of the follow-up of the machine with respect to the command from NC, and the servomotor rotates at a speed proportional to this follow-up deviation amount. Note that this follow-up deviation amount differs depending on each motor and the load of the motor, and this follow-up deviation amount in the example of the work feeder differs depending on the weight of the work as the load of the conveyor motor.

In view of the above-mentioned problems, the present invention solves the problem that one block of the movement command is eliminated to delete one block of time required for preprocessing, that is, the feed is temporarily stopped between two blocks. Therefore, the cycle time of the machine operating in the cycle can be shortened, and on the other hand, the stop accuracy is improved without increasing the stop distance by considering the amount of servo tracking deviation when the stop signal is input. Another object of the present invention is to provide a positioning method for the NC device.

[0009]

FIG. 1 is a flow chart of the basic processing of a positioning method according to the present invention. A positioning method for an NC device according to the present invention which achieves the above object, is an positioning device for an NC device, which receives an external signal during positioning and continues the positioning by a predetermined movement amount from the position being positioned when the external signal is received. In the method, the extremum in the drive direction of the drive shaft for performing the positioning is set as a command value for linear interpolation in advance, and a predetermined stop movement amount from the input of an external signal to the NC device until the stop is set in advance. During the linear interpolation instructed in the first step and the first step, the remaining moving amount obtained by subtracting the moving amount moved in each predetermined sampling period from the command value of the linear interpolation is monitored, and the remaining moving amount is monitored. Is 0, returns to the first stage, and when the remaining movement amount is not 0, proceeds to the third stage, and monitors the external signal at every predetermined sampling period,
Returning to the second stage until the external signal is input, the moving amount obtained by subtracting the tracking deviation amount at the time when the external signal is input from the stop moving amount is replaced with the remaining moving amount, The third stage of moving and stopping by the replaced remaining movement amount.

[0010]

According to the positioning method in the NC device of the present invention, an external signal is received during positioning, and the positioning in the NC device for continuing the positioning by the predetermined movement amount from the position being positioned when the external signal is received is performed in one block. If an external signal is input during execution of the linear interpolation command, the value obtained by subtracting the tracking deviation amount when the external signal is input from the predetermined movement amount is replaced with the movement amount, and linear interpolation is continued. Pre-processing for one block is omitted and positioning is performed with high accuracy.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 2 is a flow chart of processing of a method for positioning a work feeder according to the present invention. The numbers following S in the figure indicate step numbers. In explaining the figure, the NC program will be described below. N11 G01X9999.999 F1000 N12 M10 N13 M99

In the first step, a linear interpolation command is described in the first sequence number N11 of the NC program,
A stop movement amount, which is a distance moved after an external signal is input, is set in advance. In the second stage, 99 in the X-axis direction
Feed rate 1000 mm / min toward 999.999 mm
In step S21, the preprocessing for linear interpolation is executed.
Perform pulse distribution to the drive controller that drives the X-axis every msec sampling cycle, that is, output the interpolation movement amount for each sampling cycle of 8 msec to the servo drive controller to drive the servomotor (step S22), and perform the remaining movement. It is determined whether or not the amount, that is, in this example, the moving amount obtained by subtracting the moving amount moved by the linear interpolation for every sampling cycle of 89999 from 99999.999 mm (step S2).
3).

In the third step, if the answer is NO in step S23, it is determined whether or not a stop signal is input (step S24). If the stop signal does not come in step S24, the process returns to step S22 and the stop signal comes. In this case, the remaining movement amount is replaced with a value obtained by subtracting the following deviation amount during movement at that time from the preset stop movement amount, and the process returns to step S22 (step S25).

On the other hand, if the answer is YES in step S23,
The cutter 5 of the cutting machine is operated by the command of M10 in the sequence N12 (step S26), and the sequence number N13
Then, the process returns to the start address of the program, that is, step S21 (step S27), and repeats the same cycle.

[0015]

As described above, according to the positioning method in the NC apparatus of the present invention, a stop signal is received from the outside during positioning, and the stop signal is moved by a predetermined distance from the position at which the stop signal was generated. Positioning can be performed without dead time, the cycle time of a machine operating in a cycle can be reduced, and highly accurate positioning can be realized. Further, the setting of the moving distance from the stop signal detection point can be easily changed.

[Brief description of drawings]

FIG. 1 is a flowchart of basic processing of a positioning method according to the present invention.

FIG. 2 is a flow chart of processing of a method for positioning a work feeder according to the present invention.

FIG. 3 is an explanatory diagram of a work feeder.

FIG. 4 is a flow chart of processing of a method of positioning a work feeder according to the related art.

[Explanation of symbols]

 1, 1 '... Conveyor 2, 2' ... Work 3 ... Sensor 4 ... NC device 5 ... Cutter

Claims (1)

[Claims] 1. A positioning method in an NC device, which receives an external signal during positioning and continues the positioning by a predetermined movement amount from the position during positioning when the external signal is received, wherein a drive shaft for executing the positioning. A first step in which the extreme value in the driving direction is set in advance as a command value for linear interpolation, and a predetermined stop movement amount from the input of the external signal to the NC device until the stop is preset, and a command in the first step. During execution of the linear interpolation described above, the remaining movement amount obtained by subtracting the movement amount moved in each predetermined sampling cycle from the command value of the linear interpolation is monitored, and when the remaining movement amount is 0, the first step is performed. If the remaining movement amount is not 0, the second step proceeds to the third step, and the external signal is monitored at every predetermined sampling period, and returns to the second step until the external signal is input. Outside A third step of replacing the movement amount obtained by subtracting the tracking deviation amount at the time when the partial signal is input from the stop movement amount with the remaining movement amount, moving by the replaced remaining movement amount, and stopping. And a positioning method in an NC device.