JPH03113507A - Check system for absolute position signal of numerical controller - Google Patents

Abstract

PURPOSE:To shorten the time required for a check processing of the absolute position signal of a numerical controller by providing plural detectors which can always detect the absolute positions and producing a prescribed alarm signal when the difference of detection signals exceeds a set level among those detectors. CONSTITUTION:An absolute position detector 30a detects the absolute position of a machine axis 22 via the gears 23 and 24 and outputs an absolute position signal A1. At the same time, an absolute position detector 30b detects the absolute position of the axis 22 via the gears 23 and 25 and outputs an absolute position signal A2. Then the signal A1 is inputted to an axis control circuit 15 as a position feedback signal. Meanwhile a collation circuit 17 collates both signals A1 and A2 with each other and produces an alarm signal Sa when the difference between signals A1 and A2 exceeds a set level. Based on the signal Sa, processor 11 displays a prescribed alarm message on a display device 19 via a display control circuit 18 and also interrupts a shift command as necessary. As a result, the detection signals can be collated with each other at a high speed and the check processing time is shortened.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an absolute position signal checking method for a numerical control device (CNC) that checks for abnormalities in an absolute position signal input as a feedback signal to a numerical control device (CNC). This invention relates to an absolute position signal check method that requires short check processing time.

[Conventional technology]

A numerical control device (CNC) has a feedback loop for the absolute position of the machine axes. Typically, this absolute position is detected by integrating feedback pulses proportional to the amount of movement from a servo motor or a pulse coder directly coupled to the machine axis.

On the other hand, it is necessary to monitor whether the detected absolute position signal is normal or not. For example, a plurality of pulse coders are provided and determination is made based on the difference between the absolute position signals obtained from these detection signals. This determination process needs to be performed at high speed in order to improve the accuracy of the check.

[Problem to be solved by the invention]

However, since the process of calculating the absolute position by integrating the amount of movement must be performed for each pulse coder, the software processing time becomes long, and there may be a shortage of time for processing other tasks. Although there is a method of providing dedicated hardware to avoid this, the system configuration becomes complicated.

The present invention has been made in view of these points, and it is an object of the present invention to provide an absolute position signal check method for a numerical control device that has a simple configuration and shortens the check processing time.

[Means to solve the problem]

In order to solve the above problems, the present invention provides a numerical control device (
In the absolute position signal checking method of a numerical control device that checks for abnormalities in the absolute position signal input manually as a feedback signal of CNC, the absolute position of a specific machine axis is detected and each independent predetermined absolute position signal is output. An absolute position signal checking method for a numerical control device, characterized in that a plurality of absolute position detectors are provided, a difference between the plurality of absolute position signals is monitored, and an abnormality is determined when the difference exceeds a set value. is provided.

[Effect]

By using a plurality of detectors capable of constantly detecting absolute positions, there is no need to integrate feedback pulses to determine the machine position. As a result, each detection signal can be compared at high speed, and the check processing time can be shortened.

〔Example〕

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

Figure 2 shows a numerical control device (CNC) for implementing the present invention.
) is a block diagram showing the configuration of. In the figure, a processor 11 reads out a system program stored in an R○M 12 via a bus 10, and controls the overall operation of the numerical control device 1 in accordance with this system program. R
AM13 stores temporary calculation data, display data, etc.

Nonvolatile memory 14 is a battery-backed CM
It is composed of O3 and stores the cutting program, tool correction amount, parameters, etc.

The axis control circuit 15 receives a movement command from the processor 11 based on the rotation program, converts it into a speed signal, and outputs the speed signal. The servo amplifier 16 amplifies and outputs the speed signal, thereby driving the servo motor 21 and moving the mechanical shaft 22 coupled to the servo motor 21. Note that a feedback loop for detecting the rotational speed of the servo motor 21 and feeding it back to the servo amplifier 16 is provided, but it is omitted in this figure.

The absolute position detector 30a detects the absolute position of the mechanical shaft 22 through gears 23 and 24 and outputs an absolute position signal A1, and similarly, the absolute position detector 30b detects the absolute position of the mechanical shaft 22 through gears 23 and 25. Detects the absolute position and outputs the absolute position signal A2
Output. Of these, the absolute position signal A1 is manually input to the axis control circuit 15 as a position feedback signal.

On the other hand, the collation circuit 17 collates the absolute position signals AI and A2, and generates an alarm signal Sa if the difference is greater than or equal to a set value. In response to this alarm signal, the processor 11 displays a predetermined alarm message on the display device 19 via the display control circuit 18, and interrupts the movement command if necessary.

FIG. 3 is a block diagram showing the internal configuration of the absolute position detector 30a. In the figure, an encoder 31 outputs a pulse proportional to the amount of movement of the mechanical shaft 22, and a counter 32 counts up/down these pulses according to the direction of rotation. The parallel/serial converter 33 is a counter 32
It reads the output of , converts it into, for example, an 8-bit serial signal, and outputs it. Here, each of the above elements is supplied with power from a dedicated battery 34, and the absolute position of the machine shaft 22 is determined by the output signal A1 of the parallel/serial converter 33 regardless of whether the numerical control device or the machine is running or stopping. is shown.

The configuration of the absolute position detector 30b is also similar, and the explanation will be omitted.

FIG. 1 is a flowchart of the processing in the collation circuit 17 described above. In the figure, the number following S indicates the step number.

[S1] Absolute position signal A1 from absolute position detector 30a
Load.

[S2] Absolute position signal A2 from absolute position detector 30b
Load.

[S3] Find the difference ΔA between the two absolute position signals.

[S4] Determine whether the difference ΔA exceeds a set value. If it does, proceed to S5; if not, terminate.

[S5] Generate an alarm signal Sa.

The above process is repeated, for example, every 1 msec to check for abnormalities in the absolute position signal.

In the above description, an absolute position detector is provided on one machine axis, but two absolute position detectors may be provided on each of a plurality of machine axes to perform the same checking process.

Further, the absolute position detector may be provided on the axis of the servo motor, or may be provided on the mechanical axis and the axis of the servo motor so that they correspond to each other, and the two may be compared.

〔Effect of the invention〕

As explained above, in the present invention, a plurality of detectors capable of constantly detecting absolute positions are provided, and a predetermined alarm signal is generated when the difference between these detection signals exceeds a set value. Since integration processing is no longer necessary, each detection signal can be compared at high speed, and the check processing time is shortened. As a result, the time allocated to other task processing becomes longer within a certain period of time, making it possible to realize a highly functional numerical control device.

[Brief explanation of drawings]

Fig. 1 is a flowchart of an absolute position signal check method according to an embodiment of the present invention, Fig. 2 is a block diagram of a numerical control device for implementing the present invention, and Fig. 3 is an internal block diagram of an absolute position detector. be. 1 Numerical control device 17・・Verification circuit 22・・Machine axes 30a, 30b・−Absolute position detectors A1, A2 Absolute position signal Sa ° Alarm signal

Claims (2)

[Claims] (1) In the absolute position signal checking method of a numerical control device (CNC) that checks for abnormalities in the absolute position signal that is input as a feedback signal to the numerical control device (CNC), the absolute position of a specific machine axis is detected and each independent predetermined position is detected. A numerical value characterized in that a plurality of absolute position detectors that output absolute position signals are provided, a difference between the plurality of absolute position signals is monitored, and an abnormality is determined when the difference exceeds a set value. Absolute position signal check method for control equipment. (2) The absolute position signal checking method for a numerical control device according to claim 1, wherein the difference is monitored at every predetermined sampling time.