JPH01267705A - Numerical controller for working non-complete circular work piece - Google Patents

Abstract

PURPOSE:To improve a working efficiency by obtaining profile data from lift data to specify the finishing shape of a work piece and a maximum grindstone diameter selected in consideration of a permissible error with which a working is executed without generating a reverse phenomenon. CONSTITUTION:An automatic programming device 70 is composed of a front CPU 71, a RAM 72 and an input/output interface 73. To the RAM 72, a lift data area 721, an angle range data area 722, an approximate curve data area 723, a profile data area 724, an interpolation angle data area 725, a permissible error data area 726, and a grindstone diameter data area 727 are prepared. The profile data are obtained from the lift data to specify the finishing shape with a point train and the grindstone diameter of a grinding wheel, and when the central locus of the grindstone generates the reverse phenomenon, the reverse phenomenon is removed within the permissible error of the finishing shape of a non-complete circular work piece, the positions of a main spindle and a tool feeding shaft are synchronizing-controlled, and the non-complete circular work piece is worked. Thus, the working efficiency can be improved.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a numerical control device for controlling the machining of a non-perfect circular workpiece (hereinafter simply referred to as a "workpiece") such as a cam.

[Prior art]

Conventionally, a method is known in which a numerical control device controls the feed of a grinding wheel in a direction perpendicular to the spindle axis in synchronization with the rotation of the spindle to grind a workpiece such as a cam. In order to synchronously control the feed of the grinding wheel, it is necessary to provide profile data to the numerical control device. This profile data gives the amount of movement of the grinding wheel for each unit rotation angle of the main shaft so that the grinding wheel is reciprocated along the finished shape of the workpiece, that is, it is moved to create a profile. Then, the profile data is obtained from the lift data of the non-perfect round workpiece and the diameter of the grinding wheel. Here, in order to shorten the machining cycle time and obtain the desired finished shape, it is better to select a grindstone with a diameter as large as possible.

[Problem to be solved by the invention]

However, when creating profile data, because the diameter of the grinding wheel is large, a reversal phenomenon may occur in which the center locus of the grinding wheel moves in the opposite direction with respect to the rotation angle of the main shaft. In other words, the entire circumference (36
When the grindstone is attached faithfully to the angle (0°), there may be an angle with respect to the finished shape that cannot be brought into contact with the diameter of the grindstone, and the grindstone becomes floating and cannot be ground. In this case, when the profile data is calculated from the lift data and the grindstone diameter, the point sequence of the obtained profile data takes on a loop shape at the angle where contact is not possible. The angular range showing this loop shape is called the reversal phenomenon range, and within this angular range, machining that is faithful to the finished shape based on the lift data is impossible. Conventionally, in order to avoid such a situation, a grindstone with a smaller diameter was unavoidably selected, although efficiency was reduced. In this way, machining of a non-perfectly circular workpiece is performed by synchronously controlling the rotational position of the spindle and the position of the grinding wheel, but when performing profile creation motion, the diameter of the grinding wheel is adjusted based on the lift data of the non-perfectly circular workpiece. There may be cases where the selection of is too large and faithful movement is impossible. The present invention has been made to solve the above problems, and its purpose is to take into account tolerances for the required shape, prevent the center trajectory of the grindstone from reversing, The objective is to improve machining efficiency by allowing the use of the largest diameter grinding wheel and machining non-perfect circular workpieces at high speed.

[Means to solve the problem]

The configuration of the invention for solving the above problem is to generate profile data that indicates the relationship between the rotation angle of the spindle and the position of the tool feed axis according to the lift data that specifies the finished shape of a non-circular workpiece and the diameter of the grinding wheel. and a numerical control device for controlling machining of the non-perfect round workpiece according to the profile data, comprising: lift data storage means for storing the lift data; a grindstone diameter storage means for storing the grindstone diameter; calculating an angular range in which the center trajectory of the grindstone causes a reversal phenomenon in the profile data obtained from the lift data and the grindstone diameter; An angular range storage means for storing, a calculation means for smoothing the profile data within the tolerance so that the center locus of the grindstone in the angle range does not reverse, and a calculation means for smoothing the profile data by the calculation means. The present invention is characterized by comprising a position control means for numerically controlling the main spindle and the tool feed axis based on the above.

[Effect]

The shape of a non-perfect circular workpiece is given by lift data that shows the relationship between rotation angle and lift amount. The lift data specifies the finished shape of a non-perfectly circular workpiece using a series of points. Profile data is determined from this lift data and the diameter of the grinding wheel. In the obtained profile data, if the center locus of the grinding wheel causes a reversal phenomenon, convert it to smooth profile data within the tolerance of the finished shape of a non-perfect round workpiece, and
Based on the profile data from which the reversal phenomenon has been removed,
The positions of the spindle and tool feed axis are synchronously controlled to process non-perfect circular workpieces.

【Example】

The present invention will be described below based on specific examples. FIG. 1 is a configuration diagram showing a numerically controlled grinding machine. Reference numeral 10 denotes a bed of a numerically controlled grinding machine, and a table 11 driven by a servo motor 16 via a screw feeding mechanism is disposed on the bed 10 so as to be slidable in the Z-axis direction parallel to the spindle axis. . A headstock 12 having a main spindle 13 mounted thereon is disposed on the table 11, and the main spindle 13 is rotated by a servo motor 14. Further, a tailstock 15 is placed on the right end of the table 11, and the center 19 of the tailstock 15 and the center 1 of the main spindle 13 are
A workpiece W consisting of a camshaft is held between and 7. The workpiece W fits into a positioning pin 18 protruding from the main shaft 13, and the rotational phase of the workpiece W matches the rotational phase of the main shaft 13. A tool stand 20 that can move forward and backward toward the workpiece W is guided behind the bed 10, and a grinding wheel G that is rotationally driven by a motor 21 is supported on the tool stand 20. This tool stand 20 is connected to a servo motor 23 via a feed screw, and is moved forward and backward by forward and reverse rotation of the servo motor 23. The drive units 51, 52, 53 are the numerical control device 30
command pulses are input from the respective servo motors 14.
．． This is a circuit that drives 16.23. The numerical control device 30 is a device that mainly numerically controls the rotation of the control shaft to control the grinding of the workpiece W and the correction of the grinding wheel G. As shown in FIG. 2, the numerical control device 30 includes a main CPU 31 for controlling the grinding machine, a ROM 33 for storing control programs, and an RA for storing input data, etc.
It is mainly composed of M32. N for RAM32
A processing NC profile data area 321 for storing C profile data is formed. The numerical control device 30 also includes servo motors 14 and 16.
．． As a drive system of 23, drive CPU36 and RAM3
5 and a pulse distribution circuit 37 are provided. RAM35
is a storage device into which positioning data of the grinding wheel G1 table 11 and the main spindle 13 are input from the main CPU 31. The drive CPU 36 is a device that performs calculations such as slow-up, slow-down, and interpolation of target points regarding the feed of control axes related to machining, and outputs positioning data of interpolation points at regular intervals. This is a circuit that outputs a work command pulse to each drive unit (51, 52, 53). An automatic programming device 70 connected to the numerical control device 30 is a device that automatically creates profile data from lift data and grindstone diameter. That device is the front CPU71
It is composed of a RAM 72 and an input/output interface 73. RAM? 2 includes a lift data area 721 that stores lift data for a plurality of workpieces, an angular range data area 722 that stores an angular range when the point sequence of profile data causes a reversal phenomenon with respect to the angle, and a lift data area 722 that stores lift data of a plurality of workpieces. an approximate curve data area 723 for determining and storing an approximate curve in which the point sequence does not cause a reversal phenomenon with respect to the angle;
A profile data area 724 that converts lift data into profile data and stores it, and when a point sequence of the profile data causes a reversal phenomenon with respect to the angle, the profile data is interpolated with a smooth point sequence so that the reversal phenomenon does not occur. In order to determine the interpolation range for the workpiece, an interpolation angle data area 725 stores the angle for addition/subtraction to the angle that causes the reversal phenomenon, a tolerance data area 726 stores the tolerance of the finished shape of the workpiece, and a profile. Grinding wheel diameter data area 72 that stores the grinding wheel diameter when generating data
7 is formed. In addition, the front CPU 71 has an input/output interface 7.
tape reader 41 into which lift data etc. are input via 3;
A keyboard 42 for inputting data and a CRT display 43 for displaying data are connected. Next, the effect will be explained. When the device is set to data entry mode, the front C
The PU 71 reads all the lift data necessary for machining from the tape reader 41 via the input/output interface 73 and creates a lift data area 7211. Next, when the apparatus is set to the profile data creation mode, the front CPU 71 executes the program shown in FIG. 3. In step 100, the current grinding wheel diameter R stored in the grinding wheel diameter data area 727 is read, and the next step 10
2, the starting point (0
°). Next, the process moves to step 104, where the lift data area 72
The lift data L(θ) of the angle θ stored in 1 is read. Next, the process moves to step 106, and as shown in ff14a, profile data P (r, ), and the profile data P (r, α) is stored in the profile data area 724.
to be memorized. Next, the process moves to step 108, and it is determined whether or not the angle component α of the obtained profile data P (r, α) has decreased from the value of the immediately previous profile data. If so, the process moves to step 110 and the angle is stored in the angle range data area 722. For example, lift data L(θ,), L(θ1.1)
The profile data corresponding to P(r*, α-1),
If P (r*++, α, 4°), then α,〉αs
There is a relationship of +1, and the profile data is P(r,, α
, ), and the angle α is stored as the first reversal angle. Similarly, P(r,, α,) and P(rm++*
α□l) becomes α7〈α,,+I, so P(r,,
. A reversal phenomenon occurs at α7), and that angle α7 is stored as the second reversal angle. Then, the process moves to step 112, and the lift data area 7
All the lift data up to the end point (360°) stored in 21 is calculated, and it is determined whether the storage is completed. Here, if it is determined in step 108 that the rotation is not reversed, the process moves to step 112 and the above determination is made. Then, in step 112, if it is not completed, the process moves to step 114, where the angle θ is increased by Δθ, and the process returns to step 104, where the lift data L (θ+Δθ) of the angle (θ+Δθ) is read. Then, the process moves to step 106, where all the lift data up to the end point (360°) is calculated, and the execution of the program from step 114 to step 112 is repeated until all the profile data has been stored. When it is determined that step 112 is completed, step 1
16, it is determined whether or not there has been a reversal during the execution of the profile data creation program as described above, and if there has been no reversal, the program ends. When it is determined in step 116 that there is a reverse rotation, the process moves to step 118 and the interpolation angle T is read from the interpolation angle data area 725. Next, the process moves to step 120, and the interpolation angle T is subtracted from the first reversal angle α stored in the angle range data area 722 to obtain the lower limit value α, -T of the interpolation interval and the second reversal angle α, −T.
Reversal angle α. , the upper limit value α, +T of the interpolation interval is obtained by adding the capture angle T, and the lower limit value of the interpolation interval is calculated from the stored profile data P (r, α) in step 106 A plurality of N points of profile data in the angle interval between and the upper limit value are sampled. Next, proceeding to step 122, as shown in FIG.
A smooth approximate curve A for the above N points is obtained and stored in the approximate curve data area 723. Next, the process moves to step 124, in which the profile data P (r, α) of the profile data area 724 obtained in step 106 is set as ideal data, and step 1
Using the approximate curve A of the approximate curve data area 723 obtained in step 22 as approximate data, the absolute value of the difference between the ideal value on the ideal data and the approximate value on the approximate data is calculated for each predetermined angle of the profile data. , it is determined whether the error is within the tolerance stored in the tolerance data area 726. When it is determined in step 124 that the error is within the allowable error,
Proceeding to step 126, profile data P (r, α) is calculated and stored anew for each predetermined angle with respect to the angle of the interval requiring interpolation, and the program ends. Here, in step 124, if it is not within the tolerance, it is not possible to process within the required machining tolerance with the current grindstone, so the process moves to step 128,
In place of the current grindstone diameter used to execute the program described above, a smaller grindstone diameter in the grindstone diameter data area 727 is read. Then, the process returns to step 102 and the execution of the above program is repeated again. Therefore, the profile data P (r, α) from which the reversal phenomenon is finally removed is the profile f − evening region 7
24, and is transferred to the NC profile data area 321 via the front CPU 71 and main CPU 31 during actual machining of the workpiece W. Then, when a processing command signal is given from the operation panel 45,
The main CPU 31 executes cam grinding by outputting a machining command according to the NC profile data stored in the NC profile data area 321.

【Effect of the invention】

The present invention provides an angular range storage means for calculating and storing an angular range in which the center locus of the grinding wheel causes a reversal phenomenon in the profile data obtained from the lift data and the grinding wheel diameter;
To prevent the center trajectory of the grinding wheel from reversing in the angular range,
It has calculation means for smoothing profile data within tolerance, and position control means for numerically controlling the spindle and tool feed axis based on the smoothed profile data, so it is possible to control the finished shape of the workpiece. It is now possible to obtain profile data from the specified lift data and the maximum grinding wheel diameter that can be processed without causing a reversal phenomenon, which is selected within the tolerance, and by processing using that profile data, processing efficiency can be dramatically improved. This makes it possible to improve the performance.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing the overall configuration of a numerically controlled grinding machine using a numerical control device according to a specific embodiment of the present invention. FIG. 2 is a block diagram showing the electrical configuration of the numerical control device according to the same embodiment. FIG. 3 is a flowchart showing the processing procedure of the Freon CPU 71 used in the numerical control device according to the same embodiment. FIG. 4 is an explanatory diagram showing the occurrence of a reversal phenomenon in creating profile data and interpolation using an approximate curve. 10・'Ped 11・゛Table 13-Spindle 14
．． 16.23-Servo motor 15.-Tailstock 20°°
Tool stand 30 - Numerical control device 7 - Automatic programming device G Grinding wheel W... Workpiece patent applicant Toyota Machinery Co., Ltd. representative Patent attorney Fujitani Shudai 4 Goke, 0°)

Claims (1)

[Claims] Profile data indicating the relationship between the rotation angle of the spindle and the position of the tool feed axis is obtained according to the lift data that specifies the finished shape of a non-round workpiece and the diameter of the grinding wheel, and the profile data is applied to the profile data. A numerical control device that controls machining of the non-perfect circular workpiece according to the method, comprising: lift data storage means for storing the lift data; grindstone diameter storage means for storing the grindstone diameter; and finishing of the non-perfect circular workpiece. Tolerance storage means for storing a shape tolerance; Angular range storage means for calculating and storing an angular range in which the center locus of the grindstone causes a reversal phenomenon in the profile data obtained from the lift data and the grindstone diameter. and calculation means for smoothing the profile data within the tolerance so that the center locus of the grindstone in the angular range is not reversed; and based on the profile data smoothed by the calculation means, the main axis and the A numerical control device for machining a non-perfectly circular workpiece, comprising: a tool feed axis; and a position control means for numerically controlling a tool feed axis.