JPS61274847A - Method of monitoring overload in nc device - Google Patents

Abstract

PURPOSE:To improve machining accuracy by setting a limit value with the maximum value of variation in load on machining a model as the reference value and comparing a variation in load at the time of machining an actual workpiece with said reference value and monitoring said variation in load, in an NC device having a CRT display. CONSTITUTION:Machining of a model is carried out prior to actual machining by means of an NC device, and a model machining maximum load rate judging circuit 8 compares data on load rate which are coming at every defined time, with a value stored in a reference memory 81. When the whole process of model machining is competed, the maximum value of the load condition in the whole process is stored in the memory 81 as the data of the reference value Ls. And, the limit value of a load condition is operated from this reference value Ls by a limit value operating circuit 9 and stored in a limit value memory 91. And, then, both of a load condition at the time of actual machining and the maximum value of load conditions up to that time, together with the reference value of load conditions up to that time, together with the reference value Ls and the limit value, are displayed on a CRT display device 71 via a display control part 7. Also, when a load rate is above a load condition at the time of actual machining, a warning device 101 operates.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical field of the invention) This invention relates to a NO.
This invention relates to a method for monitoring the load condition of a (numerical control) device during processing.

(Technical background of the invention and its problems) When machining by NORM, the main spindle motor and feed axis motor may become overloaded due to differences in the material and shape of the workpiece, as well as wear and breakage of tools, etc. If this condition continues for a long time, the durability of machines and processing tools will deteriorate. It would be fine if an operator was always present and could monitor by listening for abnormal sounds, etc., but in the case of unmanned machining, it is necessary to have the NC device monitor this overload condition. In other words, the percentage of the current value of the main shaft and each feed shaft motor divided by the continuous rated current value of this motor is calculated as the load factor, and this load factor is displayed on the CR7 display as shown in Figure 5. 1 section L+ (0-100%), L2 as a bar graph
(100-150%).

It is displayed in different colors according to L3 (150 to 200%). However, as shown in Fig. 4, this load factor changes every time the cutting distance changes according to the machining process, but the bar graph displayed on the CR7 screen showing this load factor shown in Fig. 5 is not displayed in real time. Since this bar graph also changes, the maximum value of the load factor is displayed only momentarily, and there is a drawback that the maximum load factor in the entire machining process cannot be known.

(Object of the invention) This invention was made in view of the above-mentioned circumstances, and an object of the invention is to perform model processing prior to actual processing with an NC device, and to reduce the load fluctuation of the NC device during model processing. Detects the situation, sets a limit value using the maximum value as a reference value, displays this reference value and limit value on the CR7 display, and displays the current value of the above load fluctuation during actual workpiece machining and the current value up to the present time. It is an object of the present invention to provide an overload monitoring method for an NC device that can monitor the state of load fluctuation during actual workpiece machining while comparing it with the above-mentioned reference value and limit value by displaying the maximum value together with the maximum value.

(Summary of the Invention) In an overload monitoring method for an NC device equipped with a display device that displays the load state during machining, a model is processed prior to actual machining by the NC device, and the load state during the model machining is monitored. Detected every predetermined time,
The maximum value of the load state of all processes during machining of this model is stored as a reference value, and the limit value of the load state is calculated and stored from this reference value, and the load state during actual machining and this value up to that point are stored. The maximum value of the load condition is displayed on the above display device together with the above reference value and the above limit value, so that the load condition during actual machining can be visually confirmed, and the load condition exceeding the above load condition during actual machining is displayed. This is an overload monitoring method for NC equipment that issues an alarm when an overload occurs.

(Embodiment of the Invention) FIG. 1 is a block diagram showing an example of a device implementing an overload monitoring method in an NC device of the present invention.
Main shaft motor 011) 11 and feed shaft motor (M
2 to Mn) A current value of 12 to In is detected at predetermined time intervals by a current detector 2, and the current value detected by this current detector 2 is digitally converted by an A/D converter 3, and the load factor calculation circuit 4, the load factor (continuous rated current value divided by 1
By operating the switching device 5 from the outside, the switching device 5 is operated from the outside, so that during actual machining,
″ side, and b″ side when processing the model! fi is connected to output the load factor data. Here, the data processing process from detecting the current value to calculating the load factor as described above is performed for each motor, but since it is common to all motors, in the following explanation, only one motor, e.g.
To explain about the axis feed axis motor, during model processing, the model processing maximum load rate determination circuit 8 receives the load factor Lm(t) data sent at predetermined time intervals and the data already sent before that. The current maximum value of the load factor data is compared with Law(t') stored in the reference value memory 81 as the maximum load factor, and the larger value is determined as the maximum load at that time (1). The data stored in the reference value memory 81 is rewritten and stored as the ratio Lmm(t). The above-described operations are repeated throughout the entire process of model machining, and when the entire process of model machining is completed, the maximum load factor data of the motor during this model machining is stored in the reference value memory 81 as the reference value Ls. That's what happens. Then, the limit value wave 3I circuit 9 receives this reference value Ls data and uses a preset coefficient 1. Coefficient 2 is this standard value L
s is multiplied and stored in the limit value memory 91 as the first limit value L and the second limit value LJ12, each coefficient used when calculating each limit value depends on the characteristics of each motor and the workpiece. It varies depending on the shape of the machine, etc., and can be set arbitrarily by the operator using a keyboard or the like.

On the other hand, during the actual monitored machining performed after the model machining described above, the load factor L(t) data calculated in the same manner as during the model machining described above is displayed via the 1 display control unit 7. is displayed on the CRT display f171 corresponding to each motor, and is also sent to the monitoring machining maximum load rate discrimination φ holding circuit 6. In this discrimination holding circuit 6, as mentioned above, the previously sent The value L that is currently the maximum value among the load factor data and is held as the maximum load factor
ax(t'), and the maximum load factor Lmax(t') is held as the maximum value up to that point.
) and the maximum load rate Lmax(t
) and is also displayed as CR7 via the display control unit 7.
It is identified and displayed on the display device 71. In addition, the above load factor L (
t) The data is compared with the first limit value 1 and the second limit value 2 data by the comparator 10, and when the load factor L(t) exceeds each of the above limit values, an alarm m! tot is activated and performs a predetermined operation.

Hereinafter, reference will be made to the 70-chart illustrating the operation of the overload monitoring system for the NC device of the present invention shown in FIG.
A detailed explanation of the invention will now be given.

When a machining program by the NC device is started, before the actual machining is performed, model machining is first performed in the same state as in reality (step SL), and the spindle motor (Ml) lll feed that is to be monitored during this model machining is Axis motor')
(M2~Mm) The current value that is the load state of 12~in is sampled at every preset predetermined time,
Via the current detector 2 and A/D converter 3, the load factor calculation circuit 4 calculates the load factor R (1) (step S2), and switches it to the "b" side by external operation. It is connected to the model processing maximum load rate determination circuit 8 through the switching device 5, and the maximum load rate table m(t) is determined as described above and stored in the reference value memory 8I (step S3). , the above-mentioned operations are repeated over the entire model processing step S2, and the model processing is completed (step S0 and the reference value memory 81 mentioned above).
The maximum load factor stored in the &1s value Ls is set as the &1s value Ls (step S5), and the limit value calculation circuit 9 sets this reference value to the above coefficient 1. The coefficient a2 is multiplied and the first limit value statement! , a second limit value Lu2 is calculated (step S6),
The first limit value Lll and the second limit value 2 are stored in the limit value memory 31 (step S7).

Next, when the above-described model processing is finished and actual monitored processing is started (step 5tO), the reference value Ls, the first limit value L, and the second limit value are set as shown in FIG. The limit value L12 is identified via the display control unit 7 and CR
T display! 71 (step 5ll), and it goes without saying that the above display is performed for each motor to be monitored. The motor load factor L(t) data is sent to the monitoring machining maximum load factor determination/holding circuit 6 via the switching device 5, which is switched to the "a" side by external operation, as described in h. Then, the maximum load factor Lmax(t) up to that point (1) is calculated and held (step 513), and this current load factor L(t) and the maximum load factor Lmax up to the current time are calculated and held (step 513).
(t) is displayed on the CR7 display device 71 as a bar graph by changing the line type and silver color as shown in FIG. In the comparator 10, first, the first limit value L
ul (step 515), and this load factor L(t
) is larger than this first limit value 141, the alarm device 10
1 to issue an alarm (step S+8), and then step S+8).
If it is greater than the limit value L12 (step 517), N
The C device is stopped (step 520) and this overload monitoring operation is ended. Then, in step S15, if the load factor L(t) does not exceed the first limit value L, in step S17, the load factor L(t)
If t) does not exceed i2 limit value statement 2, return to step S12 and repeat the above operations until all steps of this monitored machining for one workpiece are completed.Step 5xs) As shown in Figure 3, the load factor L(t) at that point (1) in the entire machining process and the maximum load factor Lmax(t) up to that point are constantly displayed, and an alarm is issued by the comparator IO. It is also connected to the device 101 to perform monitored processing. When all the machining steps for one workpiece are finished T, as long as there is a workpiece to be machined the same as the above model, the process returns to step S12 and repeats the above operation (step 519), in which all the workpieces for the same model are processed. When the machining is completed, the overload monitoring method in the NC device according to the present invention ends.

(Modification of the invention) In the above embodiment, the reference value Ls, the first limit value L
The second limit value L12 is one for each motor in one model, but for example, if the entire machining process of one model is divided into several processes, the above reference value and the first limit L12 are set for each process. It is also possible to set a value and a second limit value.

In addition, using input means such as a keyboard (not shown), for example, even in the middle of a monitored machining process, the machining can be temporarily interrupted, and while looking at the CR7 screen, the above reference value and the first
In addition, the limit value and the second limit value may be modified to values suitable for the process.

(Effect of the invention) According to the overload monitoring method in the NC device of this invention,
Not only is the load factor of each motor in the monitored machining process displayed in real time on the CR7 screen, but the maximum load factor up to that point is identified and displayed, so this monitored machining process is also displayed. Reference value and first limit value set during model processing performed before.

Comparison with the second limit value can be easily checked just by visually checking the CR7 screen, and the reference value, first limit value, and second limit value can be set appropriately according to each processing process, so NC
This has the effect of not only improving the durability of the NC device and machining tools, but also improving machining accuracy without overloading the device.

[Brief explanation of drawings]

FIG. 1 is a block configuration diagram showing an example of a device implementing the overload monitoring method in the NC device of the present invention, FIG. 2 is a flowchart explaining the operation of the overload monitoring method in the NC device of the present invention, and FIG. is a diagram displayed on the CR7 display device by the overload monitoring method in the NC device of this invention, FIG. 4 is a diagram showing the fluctuation state of the load factor for explaining this invention, and FIG. FIG. 3 is a diagram displayed on a CR7 display device using an overload monitoring method. 2... Current detector, 3... A/D converter, 4...
Load factor calculation circuit, 5... Switching device 2.6... Processing maximum load factor determination/holding circuit with monitoring, 7... Display control unit, 8
...Model processing maximum load rate discrimination circuit, 9...Limit value calculation circuit, IO...Comparator, 71...CR7 display device, 81...Reference value memory, 31...Limit value memory , +01...Alarm device. Applicant's agent Yu Yasugata 4 Figures 5 Figures

Claims (1)

[Claims] In an overload monitoring method for an NC device equipped with a display device that displays the load state during machining, model processing is performed prior to actual machining by the NC device, and the maximum load state during all processes during the model processing is The value is stored as a reference value, a load condition limit value is calculated and stored from the reference value, and the load condition during actual machining and the maximum value of the load condition during actual machining are detected during actual machining. The load state during the actual machining and the maximum value of the load state during the actual machining are displayed on the display device together with the reference value and the limit value, and the load state during the actual machining is displayed on the display device. An overload monitoring method for an NC device, characterized in that an alarm is issued when the limit value is exceeded.