JPH0663844A - Numerical control machine tool - Google Patents

Abstract

PURPOSE:To perform efficient correction with highly accurate working by providing a data correcting means for correcting ideal profile data according to a phase error calculated by a phase error calculating means and a position error calculated by a position error calculating means. CONSTITUTION:Detected data showing the actually worked shape of a machined workpiece W are compared with ideal profile data determined by a phase error calculating means 30 from the finished shape of the workpiece to calculate phase errors. Next, the position error in respective phases when the data are shifted in the direction of phase coincidence by the phase error calculated by a phase error calculating means 30 is calculated by the position error calculating means 30. The ideal profile data is corrected with the position error calculated by the position error calculating means 30 and the phase error calculated by the phase error calculating means 30 by a data correcting means 30 to be used for actual working processes.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a numerically controlled machine tool for machining a non-round work piece such as a cam (hereinafter also simply referred to as "workpiece").

[0002]

2. Description of the Related Art Conventionally, a numerical control device controls the feed of a grinding wheel in the direction perpendicular to the spindle axis in synchronization with the spindle rotation,
A method of grinding a workpiece such as a cam is known. This workpiece is machined by numerically controlling the rotation of the spindle and the feed of the grinding wheel based on the machining cycle data and the profile data.In particular, it follows the command values of the spindle and tool feed axis in the profile creation motion. The quality is important for processing accuracy.

In order to reduce the correction of this tracking error,
The workpiece is once processed with the ideal profile data determined from the finished shape of the workpiece, the profile of the workpiece is measured using a cam measuring device, etc., the deviation from the ideal profile data is calculated, and the ideal profile data is corrected. Should be added.

[0004]

By the way, in the case of obtaining the deviation between the ideal profile data and the data (hereinafter referred to as the profile profile data) obtained by measuring the profile of the workpiece using a cam measuring device or the like, the profile profile of the measurement profile and the ideal profile data are obtained. It is conceivable to compare the actual measurement value of the tool feed axis and the command value with respect to the rotation angle of the main spindle of the profile data and obtain the difference. However, if an attempt is made to correct a tracking delay such that the measurement profile data is simply out of phase with the ideal profile data by such correction, the correction amount becomes a very large value,
A new tracking error may occur due to the correction.

It is also conceivable to correct the follow-up delay that is simply causing a phase shift by shifting the output timing of the command value of the tool feed axis with respect to the rotation angle of the spindle of the ideal profile data by the phase shift. Even in this case, the measured profile data and the ideal profile data do not always have the same amount of phase shift at all positions, and there is a problem that the tracking error cannot be completely corrected.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to efficiently correct profile data and improve the processing accuracy. The configuration of the invention for this purpose is to improve the ideal profile data storing means for storing the ideal profile data determined from the finished shape of the non-round work piece, and the spindle and the main shaft based on the ideal profile data. Controlling the tool feed axis, measuring means for detecting and storing the current value of the tool feed axis corresponding to the position of the spindle, and comparing the data detected by the measuring means with the ideal profile data. Phase error calculating means for calculating the phase error and the respective positions when the data is shifted in the direction in which the phases match by the phase error calculated by the phase error calculating means. Position error calculation means for calculating the position error in the position error calculation means, and the ideal profile data is corrected by the phase error calculated by the phase error calculation means and the position error calculated by the position error calculation means. And a data correction means.

[0007]

The profile of the workpiece actually machined with the ideal profile data is measured, and the actual machining is performed with the data obtained by correcting the ideal profile data by the deviation from the ideal profile data. For example, when a measurement command is issued by the measurement command means during idle operation based on the ideal profile data or when the workpiece is actually being spark-out machined, the measurement means causes the present value of the spindle and the tool to be measured. The current value of the feed axis of is detected and stored. The detected data indicates the actual machining shape when the workpiece is machined. The data is compared with the ideal profile data determined from the finished shape of the workpiece by the phase error calculating means, and the phase error is calculated. Next, the position error calculating means calculates the position error at each phase when the data is shifted in the direction in which the phases match by the phase error calculated by the phase error calculating means. Then, the ideal profile data is corrected by the position error calculated by the position error calculation means by the data correction means and the phase error calculated by the phase error calculation means and used for the actual processing.

[0008]

EXAMPLES The present invention will be described below based on specific examples. FIG. 1 is a configuration diagram showing a numerical control grinding machine.
Reference numeral 10 denotes a bed of a numerical control grinding machine, on which a table 11 is arranged slidably in the Z-axis direction parallel to the main axis. A headstock 12 having a main shaft 13 mounted thereon is arranged on the table 11, and the main shaft 13 is rotated by a servomotor 14. Further, a tailstock 15 is placed on the right end of the table 11, and a work W composed of a cam by a center 16 of the tailstock 15 and a center 17 of the spindle 13 is provided.
Are pinched. The workpiece W is fitted to the positioning pin 18 protruding from the spindle 13, and the rotation phase of the workpiece W is the spindle 1
3 coincides with the rotation phase.

Behind the bed 10 is a tool feed shaft (X axis).
A tool base 20 that can move back and forth is guided along the
A grindstone wheel G is rotatably driven by a motor 21. The tool base 20 is connected to a servo motor 23 via a feed screw (not shown) and is moved forward and backward by the forward and reverse rotation of the servo motor 23. Drive unit 40, 4
Reference numeral 1 denotes a circuit for inputting a command pulse from the numerical controller 30 to drive the servomotors 23 and 14, respectively, as shown in FIG. As shown in FIG. 13, the drive unit 40 includes a deviation counter 401 which receives a command pulse from the numerical controller 30 and a feedback pulse from the pulse generator 52, a DA converter 402 which DA converts the output of the deviation counter 401, and a speed generator 53 which outputs the DA converter 402. In addition to the normal servo system consisting of an amplifier 403 that subtracts and amplifies the output and applies a drive voltage to the servo motor, it is converted into a voltage according to the frequency of the command pulse and the voltage signal is added to the input of the amplifier 403. An FV converter 404 is provided. This FV
A velocity signal proportional to the velocity component of the profile data is added by the converter 404 to compensate for the tracking delay related to the velocity component. The same applies to the drive unit 41.

The numerical control device 30 is a device for mainly controlling the rotations of the servomotors 23 and 14 to control the grinding of the workpiece W. A tape reader 42 for inputting ideal profile data, processing cycle data, etc., a keyboard 43 for inputting control data, etc., a CRT display device 44 for displaying various information, and various control signals are output to the numerical control device 30. A control panel 45 is connected.

As shown in FIG. 2, the numerical controller 30 has a main CPU 31 for controlling the grinder, a ROM 33 storing a control program, and an RA storing input data and the like.
It is mainly composed of an M32 and an input / output interface 34. NC that stores NC data on the RAM 32
An ideal profile data area 322 for storing ideal profile data determined from the data area 321 and the finished shape of the workpiece W, an execution profile data area 323 for storing corrected execution profile data, and a phase error between the rotation speed of the spindle and the ideal A phase error storage area 328 for storing the profile data number is provided. Other,
A feed mode setting area 324 for setting various modes, a workpiece mode setting area 325, a spark out mode setting area 326, and a phase error compensation mode setting area 327 are provided.

The numerical control device 30 includes the other servomotors 2.
A drive CPU 36 and a RAM as a drive system for 3 and 14
35 and a pulse distribution circuit 37 are provided. RAM3
Reference numeral 5 is a storage device for inputting the positioning data of the grinding wheel G from the main CPU 31. Drive CPU 36 is spindle 1
3 is a device that numerically controls the tool feed axis and performs calculations such as slow-up, slow-down, and interpolation of the target point to output the positioning data of the interpolation point at a fixed cycle. The pulse distribution circuit 37 performs the pulse distribution after the pulse distribution. , A circuit for outputting a movement command pulse to each drive unit 40, 41.

Further, a sampling device 38 and a RAM 39 for storing sampling data are provided as one element of the profile measuring means. Sampling device 38
Has counters 381 and 382 for counting the feedback pulses output from the pulse generators 52 and 50.
The counters 381 and 382 are reset by inputting a reset signal from the main CPU 31,
A measurement start signal is input from 31 to start counting the feedback pulses of the tool feed axis (X axis) and the main axis (C axis). Further, the sampling device 38 has an address counter 383 which is reset by a reset signal from the main CPU 31 and is updated at every sampling. When a measurement start signal is inputted, the counters 381 and 382 are provided at regular intervals.
Value is output to the address of the RAM 39 indicated by the address counter 383.

Next, the operation will be described. The RAM 32 contains N including phase error measurement cycle data and machining cycle data.
The C data is stored, and the data structure is shown in FIG. 8 for the phase error measurement cycle data and in FIG. 9 for the processing cycle data. When the button 451 of the control panel 45 is pressed, the flag of the phase error compensation mode setting area 327 is reset and the phase error measurement cycle data based on the ideal profile data is activated. When the button 452 on the control panel 45 is pressed, the machining cycle data is activated. These NC data are decoded by the CPU 31 according to the procedure shown in the flowchart of FIG.

In step 100, one block of NC data is read out, and in the next step 102, it is judged whether or not it is the data end. In case of data end, this program is terminated. If it is not the data end, step 10
After shifting to 4 or less, the code determination of the instruction word is performed. If it is determined in step 104 that the instruction word is a G code, CP is used to determine a more detailed instruction code.
The process of U moves to step 106. Step 106
At 120, the mode is set according to the instruction code. When it is determined to be the G01 code in step 106, a flag is set in the feed mode setting area 324 in step 108 and the feed mode is set to the grinding feed mode. Similarly, when it is determined to be the G04 code in step 110, a flag is set in the spark-out mode setting area 326 in step 112, and the feed mode is set to the spark-out mode. In step 114, G5
When it is determined that the code is 0, a flag is set in the phase error compensation mode setting area 327, and the control mode is set to the phase error compensation mode in which the phase error is offset by the phase error. Further, when the G51 code is determined in step 120, the work mode setting area 32 is determined in step 121.
The flag 5 is set and the cam mode is set.

When the above-mentioned mode setting is completed, the processing of the CPU proceeds to step 122, and the processing corresponding to the NC data and the set mode is performed. Step 12
If it is determined to be G52 code in 2, the reset signal is output to the sampling device 38 in step 123, and the sampling conditions and the like are set. If it is determined to be G53 code in step 124, a measurement start signal is output to the sampling device 38 in step 126. Also, step 12
If it is determined to be a G55 code in step 8, R in step 130
Sampling data is read from AM39, measurement profile data is calculated from the data, error calculation is performed by comparison with ideal profile data, and execution profile data is created after correction calculation.

Next, in step 132, X is added to the read block.
When it is determined that the code is present, the routine proceeds to step 134, where it is determined whether the mode setting is the cam mode and the grinding feed mode (hereinafter referred to as "cam / grinding mode"). cam·
In the grinding mode, in step 140, pulse distribution for cam creation is performed. On the other hand, when the cam / grinding mode is not set, in step 136, pulse distribution that is not synchronized with normal rotation of the spindle is performed.

(A) Phase error measurement processing When the button 451 of the control panel 45 is pressed, the phase error measurement cycle data shown in FIG. 8 is decoded block by block according to the flowchart of FIG. First, block N1
With the G51 code of 10, the workpiece mode is set to the cam mode, and the ideal profile data to be used is designated by the number P1234. N1 of the next block
Initialization of sampling is performed by the G52 code of 20 and by the G53 code of the next block N130,
A measurement start signal is output to the sampling device 38.

Further, the dwell code of the G04 code has a depth of cut of 0, and the rotation speed of the spindle is 10 rpm (S1
Only the profile generation movement of 0 code) is processed by the procedure illustrated in FIG. The ideal profile data is a table in which the amount of movement of the tool feed axis for each unit rotation angle of 0.5 ° of the main spindle is represented by the number of pulses, and is referred to as D (I) by the read address I of the ideal profile data. First, in step 300, the state of the phase error compensation mode setting area 327 is examined. During the phase error measurement process, the flag is reset and the phase error compensation mode is not set. Therefore, the process proceeds to step 302 and the read address I is read. And the offset address IO are both initialized to 1. The offset address IO is used for compensating the phase error, and corresponds to the control start address of one cycle. Next, in step 304, a pulse distribution completion signal is input from the drive CPU 36, and it is determined whether or not the pulse distribution in the previous cycle is completed. If it is determined that the pulse distribution is completed, the process proceeds to step 306 and the ideal profile data D
(I) is read out, and in step 308, positioning data (movement amount and speed) of the grinding wheel G for each unit rotation angle of the spindle.
Is output to the RAM 35 for passing to the drive CPU 36. Next, at step 310, it is judged if the read address I is not less than the end address Imax of the ideal profile data. When I ≧ Imax, the read address I is set to the initial value 1 in order to return to the head of the table in step 312, and otherwise, the read address I is updated by 1 in step 314. Next, at step 316, it is judged whether or not the read address I is equal to the offset address IO, and if they are equal, it means that the control of one rotation of the spindle has been completed. If it is determined that the program has been rotated the specified number of times (two times in the NC data of FIG. 8), this program ends, and if it is determined that the specified number of rotations has not ended, the process proceeds to step 304. Then, the control of the next rotation cycle is performed.

As described above, the grinding wheel G performs the idle grinding or the spark-out processing only by the profile creating motion. During this processing, the sampling device 38 makes the present value of the main spindle and the present value of the tool feed axis. Is sampled at fixed time intervals and the data is stored in the RAM 39. That is, the sampling device 38 executes the processing of FIG. 5 at the designated sampling cycle. Step 4
The value of the counter 382 is stored at 00 and the value of the counter 381 is stored at the addresses MC (I) and MX (I) of the RAM 39 indicated by the value I of the address counter 383 at step 402, and the value I of the address counter 383 is stored at step 404. Only 1 is updated. Such processing is repeated at the sampling cycle while the main shaft makes one rotation, and sampling data is obtained.

Next, the calculation of the error is performed by the G55 code of the block N140 according to the flowchart of FIG. The sampling data obtained by the sampling device 38 is the current value for each constant time interval on both the C-axis and the X-axis, as shown in FIG. In step 500, the C-axis sampling data is interpolated to calculate a time corresponding to each unit rotation angle of the C-axis, and the X-axis current value for that time is interpolated into the X-axis sampling data. Then, the current value of the X axis corresponding to each unit rotation angle of the C axis is calculated. That is, the sampling data is converted into measurement profile data. Then step 502
Then, as shown in FIG. 11, the C-axis value θI when the X-axis takes the maximum value is obtained from the ideal profile data, and in step 504, the C-axis value when the X-axis takes the maximum value from the measurement profile data. θM is obtained. Next, at step 506, the phase error Δθ is calculated by θM−θI, and the phase error Δθ is stored in association with the ideal profile data number and the rotation speed of the spindle.

Further, in step 510, as shown in FIG. 14, the error of the measurement profile data with respect to the ideal profile data is divided into the phase error Δθ and the position error ΔX as shown by the partial enlargement A, that is, the phase is equal to the phase error Δθ. The position error ΔX (θ) at each phase when data is shifted in the matching direction is calculated. And step 512
Then, the execution profile data corrected by subtracting the position error ΔX (θ) from the ideal profile data is calculated, the data is stored in the execution profile data area 323, and is controlled in accordance with the execution profile data during actual machining.

In this way, blocks N120 to N140
Although the NC data of 1 measures the ideal profile data and the phase error corresponding to the rotation speed of one spindle,
By performing the same measurement while changing the rotation speed of the spindle and the ideal profile data, the phase error table shown in FIG. 10 is created in the phase error storage area 328. (B) Processing that compensates for phase error and position error When the button 452 of the control panel 45 is pressed, the processing cycle data shown in FIG.
Decoded block by block. First, G of block N010
The 51 code sets the workpiece mode to the cam mode and specifies the execution profile data to be used by the number P1234. G of N020 of the next block
The phase error compensation mode setting area 327 by the 50 code
Is set, and the control mode is set to the phase error compensation mode in which the processing profile data is compensated for the phase error to control the machining. The grinding feed mode is set by the G01 code of the next block N030, and the cam grinding processing is performed by X-0.1 by the existence of the X code. The F code is the amount of grinding per spindle revolution, the R code is the spindle 1
This is the grinding speed per rotation. The S code represents the rotation speed of the spindle. In the NC data of FIG. 9, F code and R
Since the specified numerical values of the code are equal, it is instructed to continuously cut at a constant speed with respect to the rotation of the spindle.

The creation of a cam that compensates for the phase error and the position error is executed according to the flowchart of FIG. First, in step 200, the cutting amount per unit rotation angle of 0.5 ° of the spindle is calculated as the number of pulses from the given F code.
Then, in step 202, the phase error table of FIG. 10 is searched from the executed profile data number and the rotation speed of the spindle, and the corresponding phase error is read. Since the phase error Δθ is caused by the tracking delay of the spindle, the phase error can be compensated by sequentially outputting execution profile data that precedes the command angle of the spindle by Δθ in the spindle rotation angle. Therefore, the address at which the execution profile data preceding the origin of the command angle of the spindle by Δθ is stored, that is, the offset address IO is calculated. Next step 20
At 4, the initial value of the read address I is the offset address I
Set to O. Next, in step 206, the drive CPU
A pulse distribution completion signal is input from 36, and it is determined whether or not the pulse distribution in the previous cycle is completed. If it is determined that the pulse distribution is completed, the process proceeds to step 208, and the execution profile data D (I) is read, In step 210, it is judged whether or not the cutting per one rotation of the spindle has been completed. This judgment is made by the numerical data designated by the F code. In this case, it is determined whether or not a cut for 0.1 mm has been made. When the cutting per one rotation of the spindle has not been completed, in step 212, the cutting amount per unit angle is added to the read execution profile data D (I) to generate the movement amount data. Positioning data which is a combination of movement amount data and speed data is output. When the cutting per spindle revolution is completed, the read execution profile data D (I) is directly used as the movement amount data in step 213. Next, at step 216, it is judged if the read address I is not less than the end address Imax of the execution profile data. When I ≧ Imax, the read address I is returned to the beginning of the table in step 218, and thus the initial value 1
Otherwise, the read address I is updated by 1 in step 220. Next, at step 222, it is judged if the read address I is equal to the offset address IO. If they are equal, it means that the control of one rotation of the spindle has been completed, and the process proceeds to step 224 to complete all the cuts. Whether or not it is determined. This determination is made based on the numerical data designated by the X code. When all the cuts have not been completed, the routine proceeds to step 206, and proceeds to the next control cycle. On the other hand, when all the cuts have been completed, the cam grinding process instructed in block N030 is completed.

Next, the spark-out process is processed by the procedure shown in FIG. 4 by the dwell code of the G04 code of the block N040. This flowchart is substantially the same as the flowchart in FIG. 7, and is different in that the cutting is not performed and the dwell processing is stopped when the main shaft rotates a specified number of times. That is, the content of the phase compensation mode setting area 327 is checked in step 300, but since the flag is set and the phase compensation mode is set, the phase error compensation processing of steps 322 and 324 similar to steps 202 and 204 is performed. Step 304 and subsequent steps are executed after the initial setting for Further, this process is different only in the control at the time of measuring the phase error, that the data used is the execution profile data, and the initial setting of the read address I and the offset address IO is different. That is, the corresponding phase error Δ from the phase error table according to the execution profile data and the rotation speed of the spindle.
θ is searched and the execution profile data that precedes the command angle of the main axis by the phase error Δθ is sequentially output for a predetermined cycle, whereby the spark-out machining in which the phase error is compensated is executed for a predetermined cycle.

The above-mentioned execution profile data is obtained by correcting the position error, and the phase error is compensated by offsetting the read address during the pulse distribution process. To be executed. By thus dividing and correcting the phase error and the position error, the correction amount of the position error that cannot be corrected by the correction of only the phase error can be reduced, and a new tracking delay due to the correction is not generated, and the C-axis The following delay can be corrected efficiently.

In the above embodiment, the sampling device 38 samples the current values of the C-axis and the X-axis at fixed time intervals, but the counter 38 for measuring the current value of the C-axis.
2 may be configured to output a timing signal each time the C-axis rotates by a unit angle, and the present value of the X-axis may be sampled using this timing signal as a sampling signal. In this case, for each unit rotation angle of the C axis, the corresponding current value of the X axis, that is, the measurement profile data can be immediately obtained.

Further, the phase error Δθ is obtained by the phase difference of the maximum value on the X axis, but as shown in FIG. 11, the difference a between the rotation angles θ ₁ and θ ₂ and the rotation angle which make the X axis value the same. It may be obtained by the average value of the difference b between θ ₃ and θ ₄ .

[0029]

According to the present invention, the ideal profile data storage means for storing the ideal profile data determined from the finished shape of the non-round work, and the spindle and the tool feed shaft are controlled based on the ideal profile data. Then, the phase error is calculated by comparing the data detected by the measuring means and the ideal profile data with the measuring means for detecting and storing the current value of the tool feed axis corresponding to the position of the spindle. Phase error calculating means, position error calculating means for calculating the position error at each phase when the data is shifted in the direction in which the phases match by the phase error calculated by the phase error calculating means, and the phase error calculating means Means for correcting the ideal profile data with the phase error calculated by the means and the position error calculated by the position error calculating means. Those were example.

Therefore, since the tracking error can be corrected separately for the phase error and the position error, the correction amount of the position error which cannot be dealt with only by correcting the phase error can be reduced.
There is an effect that the correction is efficiently performed and highly accurate machining is performed without generating a new tracking delay due to the correction.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a numerical control grinding machine according to an embodiment of the present invention.

FIG. 2 is a block diagram showing the electrical configuration of the numerical controller.

FIG. 3 is a flowchart showing a processing procedure of a CPU.

FIG. 4 is a flowchart showing a processing procedure of a CPU.

FIG. 5 is a flowchart showing a processing procedure of a CPU.

FIG. 6 is a flowchart showing the processing procedure of the CPU.

FIG. 7 is a flowchart showing a processing procedure of the CPU.

FIG. 8 is a configuration diagram of phase error measurement cycle data.

FIG. 9 is a configuration diagram of machining cycle data

FIG. 10 is a configuration diagram of a phase error table.

FIG. 11 is a configuration diagram showing a method of calculating a phase error.

FIG. 12 is an explanatory diagram showing a method for obtaining measurement profile data from sampling data.

FIG. 13 is a block diagram showing a detailed configuration of a drive circuit.

FIG. 14 is an explanatory diagram showing a method of calculating an error of measurement profile data with respect to ideal profile data.

[Explanation of symbols]

 10 Bed 11 Table 13 Spindle 14 Servo Motor 15 Tailstock 20 Tool Platform 30 Numerical Control Device 23 Servo Motor 50 Pulse Generator G Grinding Wheel W Workpiece

Front Page Continuation (72) Inventor Nobuhiro Ishihara 1-1-1, Asahi-cho, Kariya city, Aichi prefecture Toyota Koki Co., Ltd.

Claims (1)

[Claims] 1. A numerically controlled workpiece for machining a non-round workpiece based on profile data for numerically controlling a spindle and a tool feed shaft to cause a tool to generate a profile along a finished shape of a non-round workpiece. In a machine, ideal profile data storage means for storing ideal profile data determined from the finished shape of the non-round work piece, and the spindle and the tool feed shaft are controlled based on the ideal profile data to control the spindle. Measuring means for detecting and storing the current value of the tool feed axis corresponding to the position of the above, and phase error calculating means for calculating the phase error by comparing the data detected by this measuring means with the ideal profile data. When,
Position error calculating means for calculating the position error at each phase when the data is shifted in the direction in which the phases match by the phase error calculated by the phase error calculating means, and the phase error calculated by the phase error calculating means. And a data correction means for correcting the ideal profile data with the position error calculated by the position error calculation means.