JPH0751993A - Machine element life estimating method for cnc - Google Patents

Abstract

PURPOSE:To make accurate estimation of a life for a machine element, in a machine element life estimating system for a CNC (numerical control device) to estimate a life for a bearing and a feed shaft. CONSTITUTION:Disturbance load torque Yz exerted on a servo motor 63 is estimated by a disturbance load torque estimating means based on a speed signal X1z for a servo motor 63 and a current command value U1z to the servo motor 63. The disturbance load torque Yz is integrated at intervals of a sampling period by an integrating means 2 and an integrated value is fed to a life state monitoring means 3. A life level for a ball screw 64 and a bearing 65, being a machine element coupled to the servo motor 63, is previously stored and held at the life state monitoring means 3. The life levels of the machine element ball screw 64 and the bearing 65 are always compared with an integrated value by the life state monitoring means 3. When the integrated value exceeds a life level, alarm display is effected to announce it to an operator.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a CNC (Numerical Control Unit) mechanical element life estimation method for estimating the life of bearings, feed shafts, etc., and more particularly to a bearing, feed shaft, etc. connected to each motor for axis control The present invention relates to a CNC mechanical element life estimation method for estimating the life of a machine.

[0002]

2. Description of the Related Art In machine tools, robots, etc. controlled by CNC, it is necessary to replace mechanical elements such as bearings and feed shafts connected to a motor for axis control before they are deteriorated or damaged. . Therefore, conventionally, the life time of each machine element is set in advance in consideration of the operating environment, and when the machine is operated for the life time, the machine element is replaced or inspected.

[0003]

However, in the past, since the set life time was determined only by the experience of the designer / operator, it is not always accurate, and the life environment is not always correct. I could not respond.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a mechanical element life estimation method for a CNC capable of more accurately grasping the mechanical element life.

[0005]

In order to solve the above-mentioned problems, the present invention proposes a CNC (numerical control device) mechanical element life for estimating the life of bearings, feed shafts, etc. connected to respective motors for axis control. In the estimation method, a disturbance load torque estimating means for estimating a disturbance load torque acting on the motor, an integrating means for integrating the value of the estimated disturbance load torque over time, and a life of the mechanical element according to the integrated value. A mechanical element life estimation method for a CNC is provided, which comprises: a life status monitoring unit that monitors a status and notifies the life status to the outside.

[0006]

The disturbance load torque estimating means estimates the disturbance load torque acting on the motor and the estimated disturbance load torque value is integrated by the integrating means over time. The life status monitoring means monitors the life status of the mechanical element according to the integrated value and informs the life status to the outside. As a result, it is possible to perform life determination according to the integrated value of the disturbance load torque that determines the deterioration of each machine element.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 2 is a hardware block diagram of a numerical controller (CNC) for implementing the CNC mechanical element life estimation method of the present invention. In the figure, 10 is a numerical controller. The processor (CPU) 11 is a processor that is the center of control of the entire numerical controller 10, and is a bus 2
The system program stored in the ROM 12 is read via 1 and the entire numerical controller 10 is controlled according to the system program. The RAM 13 stores temporary calculation data, display data, and the like. RAM
A DRAM is used for 13. The CMOS 14 stores a processing program and various parameters. Also,
The CMOS 14 stores an integrated value of a disturbance load torque described later. The CMOS 14 is backed up by a battery (not shown) and serves as a non-volatile memory even when the power supply of the numerical control device 10 is turned off. Therefore, those data are retained as they are.

The interface 15 is an interface for an external device, and is connected to an external device 31 such as a paper tape reader, a paper tape puncher, and a paper tape reader / puncher. The processing program is read from the paper tape reader, and the processing program edited in the numerical controller (CNC) 10 can be output to the paper tape puncher.

A PMC (Programmable Machine Controller) 16 is built in the CNC 10 and controls the machine with a sequence program created in a ladder format. That is, according to the M function, S function, and T function instructed by the machining program, these are converted into necessary signals on the machine side by the sequence program and output from the I / O unit 17 to the machine side. This output signal drives a magnet or the like on the machine side to operate a hydraulic valve, a pneumatic valve, an electric actuator or the like. Further, it receives a signal from a limit switch on the machine side, a switch on the machine operation panel, etc., performs necessary processing, and passes it to the processor 11.

The graphic control circuit 18 converts the current position of each axis, alarms, parameters, digital data such as image data into an image signal and outputs it. This image signal is sent to the display device 26 of the CRT / MDI unit 25,
It is displayed on the display device 26. Interface 19 is CR
It receives data from the keyboard 27 in the T / MDI unit 25 and passes it to the processor 11.

The interface 20 is a manual pulse generator 3
2 and receives the pulse from the manual pulse generator 32. The manual pulse generator 32 is mounted on the machine operation panel,
Used to precisely position machine working parts manually.

The axis control circuits 41 to 43 receive the movement command of each axis from the processor 11 and output the command of each axis to the servo amplifiers 51 to 53. The servo amplifiers 51 to 53 receive the movement command and drive the servo motors 61 to 63 of the respective axes. The servo motor 63 that controls the Z-axis feed incorporates a pulse coder 631 for position detection, and the position signal is fed back from the pulse coder 631 to the axis control circuit 43 as a pulse train. Although not shown here, the servo motor 61 that controls the X-axis feed and the servo motor 62 that controls the Y-axis feed also
A pulse coder for position detection is built in like the servo motor 63, and a position signal is fed back from the pulse coder as a pulse train. In some cases, a linear scale is used as the position detector. Further, the speed signal X1z can be generated by subjecting this pulse train to F / V (frequency / speed) conversion.

The axis control circuit 43 has a processor (not shown) for software processing, and has an observer 410 as a part thereof. Observer 41
0 indicates the servo motor 6 in response to the above speed signal X1z and the like.
The disturbance load torque Yz acting on No. 3 is estimated. The estimated disturbance load torque Yz is sent to the processor 11. The details will be described later.

The spindle control circuit 71 receives a spindle rotation command and a spindle orientation command, and outputs a spindle speed signal to a spindle amplifier 72. The spindle amplifier 72 receives the spindle speed signal and rotates the spindle motor 73 at the commanded rotation speed. In addition, the spindle is positioned at a predetermined position according to the orientation command.

A position coder 82 is connected to the spindle motor 73 by a gear or a belt. Alternatively, the position coder 82 may be installed inside the spindle motor 73.
Are combined. Therefore, the position coder 82 rotates in synchronization with the spindle motor 73, outputs a feedback pulse, and the feedback pulse is fed back to the spindle control circuit 71. The speed signal X1s can be generated by performing F / V (frequency / speed) conversion on this pulse train.

Like the axis control circuit 43, the spindle control circuit 71 has a processor (not shown) for software processing, and has an observer 710 as part thereof. The observer 710 receives the speed signal X1s and the like and estimates the disturbance torque Ys acting on the spindle motor 73. The estimated disturbance load torque Ys
Is sent to the processor 11 in the same manner as the estimated disturbance load torque Yz described above.

The processor 11 receives these estimated disturbance load torques Yz and Ys and performs a life management process described later by a predetermined software. FIG. 3 is a block diagram of an observer for estimating the disturbance load torque. Here, the disturbance load torque includes the disturbance load torque such as the cutting load torque, the gravity load torque of the gravity axis, and the friction torque of the mechanism section, and the acceleration / deceleration torque for acceleration / deceleration is calculated from the total torque of the servo motor. Excluded.

The processing shown in this block diagram is executed by the observer 410 of the axis control circuit 43 and the observer 710 of the spindle control circuit 71, as described above. Since the observers 410 and 710 have the same configuration, the observer 410 will be described here, and the description of the observer 710 will be omitted.

In the figure, a current command value U1z is a torque command value that is output to the servo motor 63 in response to the movement command from the processor 11, and is input to the element 401 to drive the servo motor 63. The output torque of the servomotor is calculated based on the disturbance torque X in the calculation element 402.
2 is added. The output of the calculation element 402 becomes the speed signal X1z by the element 403. Here, J is the inertia of the servomotor 63.

On the other hand, the current command value U1z is the observer 41
Input to 0. The observer 410 has a current command value U1z.
Then, the disturbance load torque is estimated from the speed X1z of the servo motor 63. The speed control of the servo motor 63 is omitted here, and only the calculation for estimating the disturbance load torque will be described. The current command value U1z is multiplied by (Kt / J) in the element 411 and is output to the calculation element 412. The calculation element 412 adds a feedback signal from a calculation element 414, which will be described later, and the calculation element 413 further calculates a calculation element 415.
Add the feedback signals from. Computing elements 412 and 413
The output unit of is acceleration. The output of the calculation element 413 is input to the integration element 416 and output as the estimated speed XX1 of the servo motor 63.

A difference between the estimated speed XX1 and the actual speed X1z is calculated by a calculation element 417, and calculation elements 414 and 4 are respectively calculated.
Return to 15. Here, the proportional element 414 is the proportional constant K
Has 1. The unit of the proportionality constant K1 is sec ^-1 . The integration element 415 also has an integration constant K2. The unit of the integration constant is sec ^-2 .

Here, the output of the integration element 415 (XX2 /
J) can be calculated from the following formula from the figure. (XX2 / J) = (X1z−XX1) · (K2 / S) = (X2 / J) · [K2 / (S ² + K1 · S + K2)] Therefore, if the constants K1 and K2 are selected so that the poles are stable, The above equation becomes the following equation.

(XX2 / J) .apprxeq. (X2 / J) XX2.apprxeq.X2 That is, the disturbance load torque X2 can be estimated by XX2.
However, the output of the integration element 415 is the estimated disturbance load torque X
It is an estimated acceleration (XX2 / J) obtained by dividing X2 by J, and is converted into a current value by the proportional element 420. However,
In order to display the torque, this current value is displayed as the estimated disturbance load torque Yz. Here, J is J of the previous element 403.
Is the inertia of the servo motor 63, and Kt is the same as the torque constant of the element 401. A is a coefficient,
It is a numerical value of 1 or less and is a coefficient for correcting the estimated acceleration (XX2 / J). In this way, the observer 410
Disturbance load torque Yz (X
2) can be estimated.

Disturbance load torque Y of the spindle motor 73
Similarly, s can be estimated using the observer 710. In this case, the observer 710 determines that the current command value U1s
Then, the disturbance load torque Ys is estimated from the speed signal X1s of the spindle motor 73. The current command value U1s is a torque command value output to the spindle motor 73 in response to the spindle rotation command from the processor 11.

These estimated disturbance load torques Yz and Ys
Of course, these estimated disturbance load torques Yz and Ys, which are estimated values, will be described below as disturbance load torques. FIG. 1 is a conceptual diagram of a mechanical element life estimation method by the CNC 10 having such a configuration. Here, the boring process will be described as an example. Servo motor 63 is ball screw 64
Is rotated to control the position in the Z-axis direction and the feed speed of the spindle head 74 connected to the spindle motor 73. The speed signal X1z of the servo motor 63 is used as the disturbance load torque estimating means (observer 410) 1 of the axis control circuit 43.
Entered in.

A drill 75 is attached to the spindle head 74 of the spindle motor 73. The drill 75 processes the work 91 by the rotation of the spindle motor 73. The speed signal X1s of the spindle motor 73 is used as the disturbance torque estimating means (observer 710) of the axis control circuit 71.
4 is input.

The disturbance load torque estimating means 1 estimates the disturbance load torque Yz acting on the servo motor 63 based on the speed signal X1z of the servo motor 63 and the current command value U1z to the servo motor 63. The integrating means 2 integrates the disturbance load torque Yz for each sampling cycle, and sends the integrated value to the life state monitoring means 3. The life status monitoring means 3 is a ball screw 6 which is a mechanical element connected to the servomotor 63.
4 and the bearings 65 and the like are stored in advance in memory.

The life status monitoring means 3 constantly compares the life level of each mechanical element ball screw 64 and bearing 65 with the integrated value, and when the integrated value exceeds the life level, an alarm is displayed on the display device 26 or the like. Further, in some cases, the rotation of the servo motor 63 is stopped. Further, the life state monitoring means 3 displays the ratio of the integrated value to each life level and the like to notify the operator of the deterioration state of each machine element.

On the other hand, the disturbance load torque estimating means 4 estimates the disturbance load torque Ys acting on the spindle motor 73 based on the speed signal X1s of the spindle motor 73 and the current command value U1s to the spindle motor 73. The integrating means 5 integrates the disturbance load torque Ys for each sampling cycle and sends the integrated value to the life state monitoring means 6. The life status monitoring means 6 stores and holds in advance the life levels of bearings (not shown) in the spindle head 74, which is a mechanical element connected to the spindle motor 73.

The life status monitoring means 6 constantly compares the life level of the bearing 65 with the integrated value, and when the integrated value exceeds the life level, an alarm is displayed on the display device 26 or the like. Further, in some cases, the rotation of the spindle motor 73 is stopped. Further, the life status monitoring unit 6 displays the ratio of the integrated value to each life level and the like to notify the operator of the deterioration status of each machine element.

FIG. 4 is a diagram showing the time variation of the disturbance load torque and its integrated value. FIG. 4A shows the disturbance load torque Yz.
And (B) is a diagram showing a time change of the integrated value P. As can be seen from the figure (A), the disturbance load torque Yz increases or decreases regardless of the passage of time. The degree of this increase / decrease is determined by the processing state at that time. Each mechanical element is also loaded in proportion to the disturbance load torque Yz.

On the other hand, the integrated value P of the disturbance load torque Yz is
As shown in the figure (B), it increases with time. Assuming that the life level of a certain machine element is Pa, an alarm process for the machine element is performed at the time ta when the integrated value P exceeds the life level Pa. Further, before the life level Pa is exceeded, the remaining life etc. of the machine element is also displayed from the ratio of the present integrated value P and the life level Pa etc.

Similar characteristics can be obtained for the disturbance load torque Ys. FIG. 5 is a flowchart showing a processing procedure on the processor side for performing such a mechanical element life estimation method. [S1] The disturbance load torque Yz or the like estimated by the observer 410 or the like is read. [S2] The disturbance load torque Yz and the like are integrated. [S3] It is determined whether or not the integrated value P exceeds the life level Pa. If it exceeds, the process proceeds to step S6, and if not, the process proceeds to step S4.

[S4] Disturbance load torque and life level Pa
Compare with. [S5] The life status of each machine element is displayed. [S6] Alarm processing such as alarm display and operation stop is performed.

As described above, in this embodiment, since the disturbance load torque Yz and the like are integrated and the life of each machine element is estimated by the integrated value P, the life can be more accurately estimated.

In the present embodiment, an example in which the processor 11 performs the life estimation calculation based on the disturbance load torque Yz and the like estimated by the observer 410 and the like has been shown.
It may be performed by the PMC 16 or an external device (not shown).

Further, in the present embodiment, an example in which the life of each mechanical element connected to the servo motor 63 and the spindle motor 73 is estimated is shown, but the life of the other servo motors 61 and 62 is estimated by the same procedure. It can be performed.

[0038]

As described above, according to the present invention, the life state of the mechanical element is monitored according to the integrated value of the disturbance load torque, and the life state is notified to the outside. Therefore, the disturbance load torque for determining deterioration is determined. It is possible to estimate the life of each machine element according to the integrated value of.

Therefore, more accurate life estimation can be performed.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a mechanical element life estimation method by CNC.

FIG. 2 is a block diagram of hardware of a numerical controller (CNC) for implementing the tool damage prevention system of the present invention.

FIG. 3 is a block diagram of an observer according to the present invention.

FIG. 4 is a diagram showing a time variation of a disturbance load torque and its integrated value, (A) is a diagram showing a time variation of the disturbance load torque, and (B) is a diagram showing a time variation of the accumulated value.

FIG. 5 is a flowchart showing a processing procedure on the processor side for performing a machine element life method.

[Explanation of symbols]

 1,4 External load torque estimation means 2,5 Accumulation means 3,6 Life state monitoring means 10 Numerical control device (CNC) 11 Processor (CPU) 14 CMOS 16 PMC 43 Axis control circuit 53 Servo amplifier 63 Z axis servo motor 64 Ball screw 65 Bearing 71 Spindle control circuit 72 Spindle amplifier 73 Spindle motor 74 Spindle head 74 82 Position coder 91 Work 410,710 Observer 631 Pulse coder

Claims (3)

[Claims] 1. A mechanical element life estimation method of a CNC (numerical control device) for estimating the life of a bearing, a feed shaft, etc. connected to each motor for axis control, wherein a disturbance for estimating a disturbance load torque acting on the motor. Load torque estimating means, integrating means for integrating the estimated disturbance load torque values over time, and monitoring the life state of the mechanical element according to the integrated value,
A mechanical element life estimation method for a CNC, comprising: a life status monitoring unit that notifies the life status to the outside. 2. The life status monitoring means, when the integrated value exceeds a life judgment value preset for each machine element, notifies the outside that the machine element has reached the life. The mechanical element life estimation method for a CNC according to claim 1, wherein the method is configured. 3. The life status monitoring means constantly compares the integrated value with a life judgment value preset for each machine element,
The method according to claim 1, wherein the mechanical element life estimation method is configured to notify the remaining life state of the mechanical element to the outside.