JP2604003B2 - Numerical controller for machining non-round workpieces - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a numerical control device of a grinding machine for processing a non-circular workpiece such as a cam.

<Conventional technology> Conventionally, in this type of numerical control device, a workpiece supported rotatably sandwiched between a tailstock and a headstock of a grinding machine is synchronized with the rotation of a spindle, and a grinding wheel is moved to a spindle axis. The vertical movement is controlled to grind workpieces such as cams.

<Problems to be Solved by the Invention> In this type of numerical control device, as shown in FIG.
It is controlled by the position of the grinding wheel tip portion TPa where the grinding wheel G intersects with a line connecting the central axis Ow of the grinding wheel G and the central axis Oc of the cam C.

However, when the cam C is ground by the grinding wheel G, the side portion CS of the cam C is at the contact point TP with the grinding wheel G.
Instead of a, the contact point is TPb, and an error amount ε occurs between the position of the contact point TPb and the position of the tip end portion TPa of the grinding wheel. Therefore, in order to prevent a profile error due to the error amount ε, the workpiece is theoretically obtained from the lift data of the workpiece and the grindstone diameter, and the workpiece is once processed based on the theoretical profile data obtained in this manner. A profile error between the profile data of the workpiece and the theoretical profile data is obtained, and the profile error is corrected to the theoretical profile data, thereby creating profile data for actually processing the workpiece.

Therefore, there is a problem that it takes a lot of setup time until actual work processing.

<Means for Solving the Problems> The present invention has been made to solve the above-described problems, and includes lift data storage means 100 for storing lift data, as shown in the block diagram of FIG. Grindstone diameter storage means 101 for storing the grindstone diameter, spindle rotational speed reading means 102 for reading the rotational speed of the spindle, and the center axis of the workpiece when the grinding wheel is moved forward and backward based on the lift data and the grindstone diameter. And an inter-central distance calculating means 103 for calculating an inter-central distance between the center axes of the grinding wheels, and an inter-central distance change for calculating an inter-central distance change amount from the inter-central distance calculated by the inter-central distance calculating means. Amount calculating means 104 and inter-central distance change amount storage means 105 for storing the inter-central distance change amount and the rotational position in association with each other.
A correction coefficient storage means 106 for storing a correction coefficient such that the change amount of the intercardiac distance falls within an allowable value; and a correction coefficient stored in the correction coefficient storage means and the change amount of the intercardiac distance. Lift data correction means 107 for correcting the lift data with a correction value determined from the rotation speed of the spindle,
And a profile data creating means 108 for creating profile data from the corrected lift data corrected by the lift data correcting means.

<Operation> The center distance between the center of the grinding wheel axis and the center of the workpiece axis corresponding to the spindle position is obtained from the lift data indicating the relationship between the rotation angle of the non-circular workpiece and the lift amount and the center of the workpiece axis. The lift data for correcting the lift data is obtained by calculating the amount of change in the inter-cardiac distance from the inter-center distance, obtaining a correction value from the amount of change in the inter-cardiac distance and the rotation speed of the spindle, and multiplying the correction value by a correction coefficient. A correction value is calculated, the lift data is corrected by the lift data correction value, and profile data is created from the corrected lift data.

<Example> Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 2 is a configuration diagram showing a numerically controlled grinding machine. Reference numeral 10 denotes a bed of a numerically controlled grinding machine, on which a table 11 driven by a servomotor 16 via a feed screw mechanism is slidably provided in a Z-axis direction parallel to the main shaft axis. . A headstock 12 on which a spindle 13 is mounted is arranged on the table 11, and the spindle 13 is rotated by a servomotor 14. A tailstock 15 is placed on the right end of the table 11, and a workpiece W composed of a camshaft is held between the center 19 of the tailstock 15 and the center 17 of the spindle 13. The workpiece W is fitted on a positioning pin 18 protruding from the spindle 13, and the rotation phase of the workpiece W matches the rotation phase of the spindle 13.

A tool table 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 work table 20. This tool stand 20
Is connected to a servomotor 23 via a feed screw (not shown), and is moved forward and backward by the forward / reverse rotation of the servomotor 23.

The drive units 50, 51, and 52 are circuits that input command pulses from the numerical controller 30 and drive the servo motors 23, 14, and 16, respectively.

The numerical control device 30 is a device that mainly performs numerical control of 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. 3, the numerical controller 30 mainly includes a main CPU 31 for controlling the grinding machine, a ROM 33 storing a control program, and a RAM 32 storing input data and the like. A processing NC profile data area 321 for storing NC profile data is formed in the RAM 32.

The numerical controller 30 includes a drive CPU 36, a RAM 35, and a pulse distribution circuit as drive systems for the other servo motors 23, 14, and 16.
37 are provided. The RAM 35 is a storage device for inputting positioning data of the grinding wheel G, the table 11, and the spindle 13 from the main CPU 31.

The drive CPU 36 is a device that performs calculations such as slow-up, slow-down, interpolation of a target point, and the like, and outputs positioning data of an interpolation point at a fixed period in feed of a control axis related to machining.
The pulse distribution circuit 37 is a circuit that outputs a motion command pulse to each of the drive units 50, 51, 52 after the pulse distribution.

Reference numeral 70 denotes an automatic programming device connected to the numerical control device 30 for automatically creating profile data from lift data and grinding wheel diameter.

This automatic programming device 30 has a front CPU 71 and R
It is composed of an AM 72 and an input / output interface 73. RA
M72 includes a lift data area 721 that stores lift data Li of a plurality of workpieces, a polar lift data area 722 that polar-transforms and stores the lift data Li, and a correction data area that stores a correction value Hi of the polar lift data Pi. 723, a corrected polar coordinate data area 724 for storing the corrected polar coordinate lift data HPi, and a profile data area for storing data obtained by converting the corrected coordinate data HPi to profile data CX
725 and the center axis OG of the grinding wheel G from the center axis OW of the workpiece W
A correction coefficient storage area 726 for storing a correction coefficient α for making the lift data correction value based on the acceleration change amount DAi of the center-to-center distance Di and the spindle speed Si be the same unit system as the lift data, and a grinding wheel A grinding wheel diameter storage data area 727 for storing the grinding wheel diameter R of G and a spindle rotation speed storage area 728 for storing the rotation speed of the spindle 13 are formed.

In the above configuration, when the operator operates the keyboard 44 to set the data input mode, the front CPU 7
1 is a tape reader 4 via the input / output interface 73.
All the lift data necessary for processing from 1 is read and stored in the lift data area 721.

Next, regarding the operation of the front CPU 71 when the profile data creation mode in which the keyboard 44 is operated is set, a flow chart in FIG. 4 and a diagram showing a positional relationship in a contact state between the workpiece and the grinding wheel in FIG. It will be described based on.

In step 200, lift data Li is read from the lift data area 721. As shown in FIG. 5, the lift data Li read in the step 200 in the next step 201 is a polar coordinate obtained by specifying a point sequence on the outline of the cam C by the rotation angle θ and the radial length r (θ). The data is converted into lift data Pi and stored in the polar coordinate lift data area 722.

In step 202, the current grinding wheel diameter R of the grinding wheel G stored in the grinding wheel diameter data area 727 is read.

In step 203, the correction coefficient α is stored in the correction coefficient storage area 726.
Read from.

In step 204, the value of a read counter i for reading the polar coordinate lift data stored in the polar coordinate lift data area 722 over the entire circumference of the cam C is set to 1.

In step 205, the ith polar coordinate lift data Pi is read from the polar coordinate lift data area 722.

In step 206, the center distance Di between the center axis Ow of the workpiece W and the center axis OG of the grinding wheel G is obtained from the grinding wheel diameter R read in step 202 and the polar coordinate lift data Pi read in step 205. Is calculated.

In step 207, the amount of change in acceleration DAi of the intercardiac distance Di calculated in step 206 is calculated.

In step 208, the operator sets the spindle speed storage area 7
The rotational speed Si of the spindle 13 preset at 28 is read.

In the next step 209, the correction coefficient α, the acceleration change amount DAi of the center distance Di, and the acceleration change amount DAi of the center distance Di from the rotation speed Si of the main shaft 13 are set to the top of the cam C in steps 203, 207, and 208, respectively. For a portion where the acceleration change amount DAi increases more rapidly than the base circle portion B, such as the portion T, a correction value Hi that causes the acceleration change amount DAi to decrease is calculated and stored in the correction data area 723.

In step 210, it is determined whether the polar coordinate lift data Pi has been read over the entire circumference. If the determination is No, the process proceeds to the next step 211, where 1 is added to the counter i, and the process again proceeds to step 205.

If the determination in step 210 is Yes, step 212
Then, the polar coordinate lift data Pi stored in the polar coordinate lift data area 722 and the correction value Hi stored in the correction data area 723 are read, corrected polar coordinate lift data HPi is calculated, and the corrected polar coordinate lift data HPi is corrected. It is stored in the polar coordinate data area 724.

Next, in step 213, profile full data CX is created from the corrected polar coordinate lift data HPi, and stored in the profile data area 725.

When the profile data transfer operation is performed after the profile data CX is created in this way, the profile data CX stored in the profile data area 725 is stored.
Is transferred to the NC profile data area 321 via the front CPU 71 and the main CPU.

Then, when a processing command is input from the operation panel 45, the main CPU 31 is stored in the NC profile data area 321.
The grinding of the cam C is performed according to the NC profile data.

<Effects of the Invention> As described above, in the present invention, the amount of change in the center distance between the center axis of the workpiece and the center axis of the grindstone is determined, and the correction value of the lift data is calculated according to the magnitude of the amount of change. Then, the lift data is corrected by this correction value to create profile data, so that accurate profile data can be created even if the contact point between the grinding wheel and the workpiece changes. There is also an advantage that the operator can process the first workpiece to be processed into a desired non-circular shape only by inputting the lift data without changing the created profile data.

[Brief description of the drawings]

FIG. 1 is a block diagram for explaining the configuration of the present invention, FIG. 2 is an overall configuration diagram of a numerical control grinding machine showing an embodiment of the present invention, and FIG. 3 is a diagram for explaining the configuration of a numerical control device. Block diagram, FIG. 4 is a flowchart for explaining the operation of the front CPU, FIG. 5 is a diagram for explaining the polar lift data, and FIG. 6 is a diagram for explaining a positional relationship in a contact state between the workpiece and the grinding wheel. FIG. 10… Bet, 11… Table, 13… Spindle, 14,16,23
…… Servo motor, 15… Tailstock, 20 …… Tool table, 30…
... Numerical control unit, 70 ... Automatic programming unit, C ...
... Cam, G ... Whetstone wheel, W ... Workpiece.

Claims (1)

(57) [Claims] 1. A method for numerically controlling a main spindle and a tool feed shaft in accordance with lift data for specifying a shape of a non-circular workpiece and a grinding wheel diameter of a grinding wheel, so that the finished shape of the non-circular workpiece is formed on the tool. A lift data storage means for storing the lift data, and a grindstone diameter storage for storing the grindstone diameter in a numerical control device for controlling the processing of the non-circular workpiece by obtaining profile data for performing profile creation motion along the same. Means, spindle speed reading means for reading the number of revolutions of the spindle, the workpiece central axis and the central axis of the grinding wheel when the grinding wheel is moved forward and backward based on the lift data and the grinding wheel diameter. An inter-cardiac distance calculating means for calculating an inter-cardiac distance between the hearts; an inter-cardiac distance change amount calculating means for calculating an inter-cardiac distance change amount from the inter-cardiac distance calculated by the inter-cardiac distance calculating means; Change in distance Inter-center distance change amount storage means for storing the amount and the rotational position of the spindle in association with each other; correction coefficient storage means for storing a correction coefficient such that the change amount of the inter-center distance falls within an allowable value; Lift data correction means for correcting the lift data with a correction coefficient stored in a coefficient storage means, a change amount of the inter-center distance, and a correction value obtained from the number of revolutions of the spindle, and correction by the lift data correction means And a profile data creating means for creating profile data from the corrected lift data obtained.