JPH0663845A - Numerical control machine tool - Google Patents

Abstract

PURPOSE:To provide efficient highly accurate working by providing a data correcting means for correcting ideal profile data on the basis of errors calculated by an error calculating means. CONSTITUTION:A data sampling means 30 detects the present values of a spindle 13 and a feed shaft of a tool G in every fixed time interval to obtain sampling data. The sampling data is interpolated by a data converting means 30 to obtain data showing a position of the tool feed shaft relative to the rotary angle of the spindle 13. Next, the data converted by the error calculating means 30 is compared with ideal profile data to calculate errors and the ideal profile data are corrected by the data correcting means 30 on the basis of the errors 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. The 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.Especially, the followability to the command value of the spindle and the tool feed axis in the profile creation motion is Quality is an important issue in terms of processing accuracy.

In order to reduce this tracking delay error, the workpiece is once processed with ideal profile data determined from the finished shape of the workpiece, and the profile of the workpiece is measured using a cam measuring device or the like. Then, the sampling data is obtained to obtain the deviation between the sampling data and the ideal profile data, and the ideal profile data may be corrected.

[0004]

When the profile of the workpiece is measured using a cam measuring device or the like and the deviation from the ideal profile data is obtained, it is necessary to compare the sampling data with the ideal profile data. . In order to compare the sampling data and the ideal profile data, for example, if the ideal profile data is given at the position of the tool feed shaft at the spindle rotation angle, the tool feed shaft at the same spindle rotation angle as this is given. It is necessary to detect the position.

However, in order to detect the position of the tool feed shaft at this spindle rotation angle, the spindle rotation angle is detected, and from this detection signal it is further detected that the spindle rotation angle included in the ideal profile data has been rotated. It is necessary to perform processing to detect the current position of the tool feed axis,
There was a problem that processing became complicated.

[0006]

The structure of the invention for solving the above problems is an ideal profile data storage means for storing ideal profile data determined from the finish shape of a non-round work piece, and the ideal profile data storage means. Data sampling means for controlling the spindle and the tool feed axis based on data, detecting and storing the present value of the spindle and the present value of the tool feed axis at constant time intervals, and the data sampling means. Data conversion means for obtaining data indicating the position of the tool feed axis with respect to the rotation angle of the spindle by interpolating sampling data consisting of the detected present value of the spindle and the present value of the tool feed axis at each fixed time interval. Error calculation means for calculating an error by comparing the converted data with the ideal profile data, and the error calculation means. It is obtained by a data correcting means for correcting the ideal profile data based on the calculated by error.

[0007]

The data sampling means detects the present value of the spindle and the present value of the feed axis of the tool at regular time intervals to obtain sampling data. Then, data indicating the position of the tool feed axis with respect to the rotation angle of the spindle is obtained by interpolating this sampling data by the data conversion means, and the data converted by the error calculation means and the ideal profile data are compared. Then, the error is calculated, and the ideal profile data is corrected by the data correction means based on this error 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 moved forward and backward by a forward and reverse rotation of a servo motor 23 via a feed screw (not shown). The drive units 40 and 41 are circuits for inputting command pulses from the numerical control device 30 and driving 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 converts the output of the deviation counter 401, and a speed generator 5 which outputs the DA converter 402.
FV converter 404 for subtracting and amplifying the output of No. 3 and adding it to the input of amplifier 403 for applying the drive voltage to the servo motor
Thus, a velocity signal proportional to the velocity component of the profile data is added, and the tracking delay related to the velocity component is compensated.
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 for numerically controlling the tool feed axis and the tool feed axis to perform operations such as slow-up, slow-down, compensation of the target point, etc., and output the positioning data of the compensation point in a fixed cycle.
Reference numeral 7 is a circuit for outputting a movement command pulse to each drive unit 40, 41 after pulse distribution.

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 that the code is the G04 code in step 110, the 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. Also, in step 114, G0
When it is determined that the code is 5, the flag is reset 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 it is determined to be the G51 code in step 120, the workpiece mode setting area 3 is selected in step 121.
The 25 flag is reset and the workpiece 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 the AM 39, 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, when it is determined in step 132 that there is an X code in the read block, the process proceeds to step 134, and it is determined whether the mode setting is the cam mode and the grinding feed mode (hereinafter referred to as "cam / grinding mode"). In the cam / grinding mode,
In step 140, pulse distribution for cam creation is performed. On the other hand, if the cam / grinding mode is not set, step 1
At 36, pulse distribution is performed that is not synchronized with normal spindle rotation.

(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 N
The G51 code of 110 sets the workpiece mode to the cam mode and specifies the ideal profile data to be used by the number P1234. N of the next block
With the G52 code 120, 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 expressed in 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 checked. Since the flag is reset and the phase error compensation mode is not set during the phase error measurement process,
In step 302, the read address I and the offset address IO are both initialized to 1. Here, the offset address IO is used for compensating the phase error, and is set as the control start address of one cycle. Correspond.
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, the positioning data (movement amount and speed) of the grinding wheel G for each unit rotation angle of the main spindle is determined by the drive C.
It is output to RAM 35 for delivery to PU 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. I
If ≧ Imax, the read address I in step 312
Is set to the initial value 1 in order to return it to the beginning of the table, otherwise the read address I is updated by 1 in step 314. Next, in step 316, the read address I
Is equal to the offset address IO,
If they are the same, it means that the control of one rotation of the main spindle is completed, and it is determined that the main spindle is rotated by moving to step 318, and it is determined that the main spindle has rotated the designated number of times (two times in the NC data of FIG. 8). If this is the case, this program is terminated, and if it is determined that the designated number of rotations has not been terminated, then the flow shifts to step 304, and 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 detects the current value of the main spindle and the current 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 error calculation is performed according to the flowchart of FIG. 6 by the G55 code of block N140. 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 sampling data of the C-axis is interpolated to calculate the time corresponding to each unit angle of the C-axis, and the current value of the X-axis for that time is obtained by interpolating the sampling data of the X-axis. , The current value of the X axis corresponding to each unit rotation of the C axis is obtained. That is, the sampling data is converted into measurement profile data. Next, at step 502, as shown in FIG. 11, the C-axis value θM when the X-axis takes the maximum value is obtained from the ideal profile data. 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, the error of the measured profile data with respect to the ideal profile data is calculated by dividing it into a phase error Δθ and a position error ΔX as shown in partial enlargement A, as shown in FIG. And step 512
The position error ΔX (θ) at each phase is calculated with, the execution profile data corrected by subtracting the error ΔX (θ) from the ideal profile data is calculated, and the data is stored in the execution profile data area 323. When processing, the control is performed according to this execution profile data.

Thus, the blocks N120 to N140 are
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 spindle rotation speed. In the NC data of FIG. 9, since the designated values of the F code and the R code are equal, it is designated 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 subtracted from the given F code as the number of pulses. 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. Phase error Δ
Since θ is caused by the tracking delay of the spindle, the phase error can be compensated by sequentially outputting execution profile data that precedes the spindle command angle by Δθ with respect to the spindle command 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, at step 204, the initial value of the read address I is set to the offset address IO. Next, in step 206, 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 208 and the execution profile data D (I ) Is read out, and it is determined in step 210 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 data and speed data, is output. When the cutting per spindle rotation is completed, the read execution profile data D (I) is directly used as the movement amount data in step 213. Next, at step 216, the read address I
Is greater than or equal to the end address Imax of the execution profile data. Step 21 if I ≧ Imax
In 8 the read address I is set to the initial value 1 to return it to the beginning of the table, otherwise the read address I is updated by 1 in step 220. Next step 22
In 2, it is determined whether 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 determine whether all the cuts have been completed. 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 from the fact that no cutting is performed and that the dwell process is stopped when the spindle has rotated a specified number of times. That is,
Although the contents of the phase compensation mode setting area 327 are checked in step 300, since the flag is set and the phase compensation mode is set, the phase error compensation process of steps 322 and 324 similar to steps 202 and 204 is performed. After the initial setting, steps 304 and below are executed. Further, this processing 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 Δθ is ground from the phase error table in accordance with the execution profile data and the rotation speed of the spindle, and the phase error Δθ with respect to the command angle of the spindle.
By outputting the execution profile data that precedes by only a predetermined cycle, the spark-out processing in which the phase error is compensated is executed for a predetermined cycle.

The execution profile data described above includes position errors.
It has been corrected, and the read address has been
Offsetting the phase compensates for the phase error.
So, in the end, the machining that compensates the total error by both is actually
Done. In the above embodiment, the phase error Δθ is the X axis.
It is calculated by the phase difference of the maximum value of, but as shown in FIG.
Rotation angle θ with the same X-axis value₁, Θ₂Difference a and rotation angle
θ ₃, Θ_FourAlternatively, the average value of the difference b may be calculated.

Although the error is decomposed into the components of the phase error and the position error by the error compensation and the error compensation is performed according to each component, only the phase error may be compensated. FIG. 15 is a diagram showing an error when the speed control means is not provided, FIG. 16 is a diagram showing an error when the speed control means is provided, and FIG. 17 is a view showing the error when the speed control means is provided and the position error is further corrected. It is a figure which shows the error at the time of processing by execution profile data. As is apparent from this, it can be seen that the errors are sequentially improved.

[0027]

The present invention detects the present value of the spindle and the present value of the tool feed axis at regular time intervals and interpolates sampling data consisting of the present value of the spindle and the present value of the tool feed axis to perform the spindle operation. Since the data showing the position of the tool feed axis with respect to the rotation angle of is calculated and the error is calculated by comparing the data with the ideal profile data, sampling data can be detected only by detecting that a certain time has elapsed. ,
There is an effect that ideal profile data can be corrected according to an error with a simple configuration, and highly accurate processing can be efficiently performed.

[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.

FIG. 15 is a characteristic diagram showing measured errors.

FIG. 16 is a characteristic diagram showing measured errors.

FIG. 17 is a characteristic diagram showing measured errors.

[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

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Nobuhiro Ishihara 1-1-1, Asahi-cho, Kariya city, Aichi prefecture Toyota Koki Co., Ltd.

Claims (1)

[Claims] 1. A numerically controlled machine 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 the non-round workpiece. In the machine, ideal profile data storage means for storing ideal profile data determined from the finished shape of the non-round work, and the spindle and the tool feed axis are controlled based on the ideal profile data, and a fixed time is maintained. Data sampling means for detecting and storing the present value of the spindle and the present value of the tool feed axis for each interval, and the present value of the spindle and the tool feed for each of the constant time intervals detected by the data sampling means Data that indicates the position of the tool feed axis with respect to the rotation angle of the spindle is interpolated by interpolating the sampling data consisting of the current values of the axes. Data converting means, error calculating means for calculating an error by comparing the converted data with the ideal profile data, and data correcting means for correcting the ideal profile data based on the error calculated by the error calculating means. A numerically controlled machine tool equipped with and.