JPH05274025A - Numerical controller for grinder - Google Patents

Abstract

PURPOSE:To improve the grinding efficiency and also to improve the machining accuracy. CONSTITUTION:A work W is supported pivotally on a grinder 50 by a spindle 55 and a tail spindle 57 and then revolved by the spindle 55. Meanwhile a grinding wheel 60 is held on a grindstone stage 61 and revolved by a grinding wheel driving motor 62. The stage 61 is also is vertically moved by a grindstone feeding motor 63. The radius sizes of the work W and the wheel 60 which are measured by a size measuring device 40 are added together in a grinding process. Then the position of the stage 61 is subtracted from the added sizes of both radius so that the residual grinding amount is obtained. At the same time, the proper maximum and minimum allowance ranges are calculated to the residual grinding amount based on the present feeding velocity of the stage 61. Then the feeding velocity of the stage 61 is controlled so that the residual grinding amount is set within both allowable ranges. Thus the satisfactory cutting quality of the grindstone is always kept. Then the grinding accuracy is improved and at the same time the grinding time is shortened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a numerical control device for a grinding machine, and more particularly to a device for adaptively controlling the feed of a grinding wheel head.

[0002]

2. Description of the Related Art Conventionally, in a grinding process using a grinder, an operator sets or automatically determines processing conditions such as a work speed and a wheel head feed speed so as to satisfy a required processing result. .. In this way, the feed (cutting) of the grindstone head with respect to the workpiece is controlled based on the speed set in advance before processing.

[0003]

By the way, in the grinding process of a grinding machine, the grinding state changes from moment to moment depending on the current diameter of the workpiece, the sharpness of the grindstone and the surrounding environment. For this reason,
Even if the same workpiece is ground under the same conditions, there is a problem that variations in the grinding accuracy may occur for each workpiece or that the grinding dimension may fall outside the allowable range. As a countermeasure for this, it is possible to set the processing conditions by assuming the worst case as described above in advance, but there is a problem that the processing time becomes long as a result.

The present invention has been made to solve the above problems, and an object of the present invention is to perform efficient grinding and improve processing accuracy.

[0005]

SUMMARY OF THE INVENTION The structure of the invention for solving the above-mentioned problems is a grinding machine for machining a workpiece by moving a grindstone base on which a grindstone is supported by a workpiece at a predetermined feed speed. In the numerical control device for use, a sizing device for measuring the outer diameter of the workpiece, and a remaining grinding amount based on the outer diameter of the workpiece measured by the sizing device and the wheel head position Grinding residual amount calculating means, allowable value calculating means for calculating maximum and minimum allowable values that are limits of an appropriate permissible range for the grinding residual amount based on the current feed speed of the grinding wheel head, and the grinding residual amount. Speed change means for changing the current feed speed of the wheel head based on the result of comparison with the maximum and minimum allowable values.

[0006]

According to the above means, the axial distance between the workpiece and the grindstone, which is calculated based on the outer diameter dimension of the workpiece and the grindstone diameter, and the workpiece and the grindstone calculated from the grindstone position. The difference from the axial distance is calculated as the remaining grinding amount. Further, the maximum and minimum allowable values within the appropriate allowable range for the remaining amount of grinding are calculated based on the current feed speed of the wheel head. Then, the remaining grinding amount is compared with the maximum and minimum allowable values. As a result, if the remaining grinding amount is larger than the maximum allowable value, the current feed speed of the grinding wheel head is low, and conversely, if the remaining grinding amount is smaller than the minimum allowable value, the current feed speed of the grinding wheel head is increased. In this way, the feed rate of the grinding wheel head in the grinding process is controlled to be always optimum.

[0007]

EXAMPLES The present invention will be described below based on specific examples. FIG. 1 is a configuration diagram showing the overall mechanical configuration of a grinding machine having a numerical controller according to the present invention. Reference numeral 50 denotes a grinder, and a table 52 that slides with respect to the bed 51 is provided on a bed 51 of the grinder 50. The table 52 is moved in the left-right direction in the drawing by driving the table feed motor 53. or,
A headstock 54 and a tailstock 56 are arranged on the table 52. The headstock 54 has a main shaft 55 and the tailstock 56 has a tailstock 57. The work W is pivotally supported by the main shaft 55 and the tailstock shaft 57, and is rotated by the rotation of the main shaft 55. The rotation of the spindle 55 is performed by a spindle motor 59 arranged on the headstock 54. On the other hand, a grinding wheel 60 for grinding the workpiece W is supported on a grinding wheel base 61 and is rotationally driven by a grinding wheel driving motor 62. Further, the whetstone base 61 is controlled to move in the vertical direction in the drawing by a whetstone head feeding motor 63. The table feeding motor 53 and the grinding wheel head feeding motor 63 are servo motors, and a numerical controller 30 is provided for numerically controlling them.

As shown in FIG. 2, the numerical control device 30 mainly includes an RO that stores a CPU 31 and a control program.
It is backed up by a battery M32, and comprises a RAM 33, an input / output interface 34, and a pulse distribution circuit 35. Further, the operation panel 20 is attached to the CPU 31 via the input / output interface 34. On the operation panel 21 of the operation panel 20, a keyboard 22 for inputting data and a CRT display device 23 for displaying data are displayed.
And are provided. Further, the pulse distribution circuit 35 is connected to the CPU 31, and the drive circuit 3 that drives the table feed motor 53 and the wheel head feed motor 63, respectively.
6, 37 are connected to the pulse distribution circuit 35. In the RAM 33, an NC data area 331 that stores NC data, a feed speed setting area 332 that sets the feed speed of the grinding wheel base 61, a grinding wheel diameter storage area 333 that stores the current grinding wheel diameter of the grinding wheel 60, and a sizing device 40. Constant value storage area 334 for storing the diameter of the workpiece W measured by the following, a grinding residual quantity storage area 335 for storing a grinding residual quantity to be described later, and maximum and minimum allowable limits which are limits of an appropriate allowable range for the grinding residual quantity. A maximum / minimum allowable value storage area 336 for storing values is formed.

Next, the CP used in the apparatus of this embodiment.
Based on the flowchart of FIG. 3 showing the processing procedure of U31, description will be made with reference to FIG. 4 showing the relationship between the grindstone diameter and the sizing value during grinding. Sizing device 40 in step 100
Outer diameter 2R _W of the workpiece W measured during grinding at
Is read. Then, the radius of the workpiece W is stored in the sizing storage area 334 of the RAM 33 as the sizing value R _W. Next, in step 102, the distance (grind head position) G _P from the spindle rotation center position, which is the mounting center of the workpiece W during grinding, to the center position of the grinding wheel 60 mounted on the grind head 61. It is read by an encoder 64 that is coaxially attached to the wheel head feed motor 63.
Next, the process proceeds to step 104 of achieving the grinding residual amount calculating means, and the grinding residual amount Δ is calculated. The remaining amount of grinding Δ is the radius dimension R _W and RA of the workpiece W read in step 100.
The wheel radius R _G stored in advance in the wheel diameter storage area 333 of M33 is added, and the wheel head position G _P read in step 102 is subtracted to obtain the value as shown in the following equation. The value of the remaining grinding amount Δ is stored in the remaining grinding amount storage area 335 of the RAM 33. Δ = (R _W + R _G ) −G _P Due to the existence of the above grinding residual amount Δ, the grinding wheel edge of the circumferential end surface of the grinding wheel 60 interferes with the workpiece W and the surface of the workpiece W can be ground.

Next, the process proceeds to step 106 for achieving the allowable value calculating means, and the feed speed setting area 332 of the RAM 33 is set.
The maximum allowable value Δmax and the minimum allowable value Δmin, which are the limits of the appropriate allowable range for the remaining grinding amount Δ calculated in step 104, are calculated based on the current feed speed V of the wheel head 61 stored in the table. That is, if the grinding condition of the grindstone is good, minimum allowable value Δmin <remaining amount of grinding Δ <maximum allowable value Δmax
The relationship will be established. These maximum allowable values Δmax
And the minimum allowable value Δmin are stored in the maximum / minimum allowable value storage area 336 of the RAM 33. The allowable value may be calculated by multiplying the current whetstone 61st feed speed V by a predetermined coefficient, or the allowable value according to the feed speed V may be stored in advance. Then, the process proceeds to step 108, and the remaining grinding amount Δ calculated in step 104 is the maximum allowable value Δmax calculated in step 106.
It is determined whether or not it is greater than. If the remaining grinding amount Δ is larger than the maximum allowable value Δmax in step 108, the process proceeds to step 110 for achieving the speed changing means, and the current feed speed V of the wheel head 61 is too fast, and grinding failure occurs. To judge. Then, assuming that the current feed speed V of the grindstone base 61 is not slowed down, the grindstone is not well cut and cannot be ground, and the deceleration processing is executed based on the following equation. V ′ = V−β where β = f (V, Δ, Δmax)

If the remaining amount of grinding Δ is less than the maximum allowable value Δmax and the inequality is not satisfied in step 108, the process proceeds to step 112, where the remaining amount of grinding Δ is greater than zero and the minimum allowable value calculated in step 106. It is determined whether it is smaller than Δmin. When the remaining amount of grinding Δ is larger than zero and smaller than the minimum allowable value Δmin in step 112, the process proceeds to step 114 for achieving the speed changing means, and although the grinding is satisfactory, the feed speed V is too slow and the machining time is left as it is. Judge that it takes too much. Then, it is assumed that sufficient grinding can be performed even if the current feed speed V of the wheel head 61 is made higher, and the acceleration processing is executed based on the following equation. V ′ = V + α However, α = f (V, Δ, Δmin) If the remaining grinding amount Δ is equal to or more than the minimum allowable value Δmin even in the above step 112 and the inequality is not satisfied, the present remaining grinding amount Δ is appropriate. That is, this program is terminated assuming that the current feed speed V of the grinding wheel head 61 is appropriate and the grinding is good. Further, when the remaining amount of grinding Δ is less than or equal to zero and the inequality is not satisfied in the above step 112, the cutting edge of the grinding wheel 60 is not cut into the workpiece W and it is still before the actual grinding process, so that the present grinding wheel is used. The feed speed V of the table 61 is maintained. In addition, after the processing in step 110 and step 114, in order to confirm the speed change, it is substantially several hundred msec.
It takes some time. As described above, in the grinder utilizing the numerical control device of the present invention, the feed speed V of the grindstone base 61 is appropriately changed based on the magnitude of the remaining grinding amount Δ during the grinding process and set according to the sharpness of the grindstone. As a result, a stable grinding system is obtained and the grinding time is shortened.

[0012]

The present invention is configured as described above, and the change control is performed so that the feed speed of the grinding wheel head is always within a good grinding range based on the size of the remaining grinding amount during the grinding process. To be done. As a result, there is an effect that a stable grinding accuracy can be obtained and a grinding processing time can be shortened by setting the feed speed according to the sharpness of the grindstone with respect to the workpiece.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an overall mechanical configuration of a grinding machine having a numerical control device according to a specific embodiment of the present invention.

FIG. 2 is a block diagram showing an electrical configuration of a numerical control device and an operation panel according to the device of the embodiment.

FIG. 3 is a flowchart showing a processing procedure of a CPU used in the apparatus of the embodiment.

FIG. 4 is an explanatory view showing a relationship between a grindstone diameter and a sizing value at the time of grinding by the apparatus of the embodiment.

[Explanation of symbols]

 20-Operation panel 21-Operation panel 22-Keyboard 23-CRT display device 30-Numerical control device 31-CPU 40-Sizing device 50-Grinding machine 51-Bed 52-Table 53-Table feed motor 54-Spindle head 55 -Spindle 56-tailstock 57-tailstock 59-spindle motor 60-grinding wheel 61-grinding wheel 62-grinding wheel drive motor 63-grinding wheel feed motor W-workpiece step 100-104-remaining grinding amount calculation Means Step 106-Allowable Value Calculation Means Steps 110, 114-Speed Changing Means

Claims (1)

[Claims] 1. A numerical control device for a grinding machine, which grinds a work by moving a grindstone base in which a grindstone is supported on a work at a predetermined feed speed, and measures an outer diameter of the work. A sizing device, a grinding residual amount calculating means for calculating a grinding residual amount based on the outer diameter dimension of the workpiece measured by the sizing device and the grinding wheel position, and a current feed rate of the grinding wheel A permissible value calculating means for calculating the maximum and minimum permissible values, which are the limits of an appropriate permissible range for the remaining grinding amount, based on the result of comparison between the remaining grinding amount and the maximum and minimum allowable values. A numerical control device for a grinding machine, comprising: a speed changing means for changing a current feed speed.