JP3084914B2 - Numerical control unit for grinding machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art Conventionally, in a grinding process using a grinding machine, an operator sets or automatically determines processing conditions such as a rotational speed of a workpiece and a feed speed of a grinding wheel head so as to satisfy a required processing result. . As described above, the feed (cutting) of the grindstone head to the workpiece is controlled based on the speed set in advance before machining.

[0003]

Incidentally, in the grinding of a grinding machine, the grinding state changes every 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 has been a problem in that variations in grinding accuracy occur for each workpiece and that the grinding dimensions are out of an allowable range. As a countermeasure against this, it is conceivable to set the processing conditions by assuming the worst case as described above in advance.

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

[0005]

According to an aspect of the present invention, there is provided a grinding machine for processing a work by moving a grindstone base on which a grindstone is supported with respect to a work at a predetermined feed speed. A numerical controller for measuring the outer diameter of the workpiece, and calculating the remaining grinding amount based on the outer diameter of the workpiece measured by the sizing device and the position of the grinding wheel head. Grinding remaining amount calculating means and current feed of the grinding wheel head
It is the limit of the allowable range that allows appropriate grinding corresponding to the speed.
The maximum allowable value and the minimum allowable value of the remaining grinding
Calculated from the degree and a predetermined coefficient, or
According to the feed speed of the wheel head stored in correspondence with the degree
Allowance calculated from the maximum allowable value and the minimum allowable value of the remaining grinding amount
Value calculating means, the grinding remaining amount, the maximum allowable value and the minimum value
By comparing with the allowable value, the remaining grinding amount is equal to the maximum allowable value.
If it exceeds, reduce the current feed rate to
If the amount is smaller than the minimum allowable value, the current feed rate
Speed changing means for increasing the speed .

[0006]

According to the above means, the distance between the axis of the workpiece and the grindstone calculated on the basis of the outer diameter of the workpiece and the diameter of the grindstone, and the distance between the workpiece and the grindstone calculated from the position of the grindstone base are calculated. The difference from the inter-axis distance is calculated as the remaining grinding amount. Next, suitability of Huh for the residual grinding amount based on the current feed rate of the wheel head
A maximum allowable value and a minimum allowable value, which are acceptable ranges, are calculated .
This is calculated from the feed rate and a predetermined coefficient, or
Is performed by storing it corresponding to the feed speed.
You. Then, the grinding remaining amount is compared with the maximum allowable value and the minimum allowable value. 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 small, and if the remaining grinding amount is smaller than the minimum allowable value, the current feeding speed of the grinding wheel head is increased. In this way, the feed speed of the grinding wheel head in the grinding process is controlled so as to always be optimal.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to specific embodiments. FIG. 1 is a configuration diagram showing an overall mechanical configuration of a grinding machine having a numerical control device according to the present invention. Reference numeral 50 denotes a grinding machine, and a table 52 that folds with respect to the bed 51 is provided on a bed 51 of the grinding machine 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 disposed on the table 52. The headstock 54 has a spindle 55, and the tailstock 56 has a tailstock 57. The workpiece W is supported by a main shaft 55 and a 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 table 61 and is driven to rotate by a grinding wheel drive motor 62. The movement of the wheel head 61 is controlled by a wheel head feed motor 63 in the vertical direction in the drawing. The table feed motor 53 and the grindstone feed motor 63 are composed of servo motors, and a numerical controller 30 is provided for numerically controlling these.

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

Next, the CP used in the apparatus of this embodiment is
Based on the flowchart of FIG. 3 showing the procedure of U31, description will be given with reference to FIG. 4 showing the relationship between the grinding wheel diameter and the fixed size value at the time of grinding. In step 100, the sizing device 40
Diameter 2R _W of workpiece W measured during grinding
Is read. The radius of the workpiece W is stored in the sizing storage area 334 of the RAM33 as Teisunchi R _W. Next, the process proceeds to step 102, where the distance (grinding wheel head position) G _P from the center of rotation of the spindle, which is the mounting center of the workpiece W being ground, to the center position of the grinding wheel 60 mounted on the grinding wheel head 61, The data is read by an encoder 64 coaxially mounted on the wheel head feed motor 63.
Next, the process proceeds to step 104 for achieving the remaining grinding amount calculation means, and the remaining grinding amount Δ is calculated. Radius R _W and the RA of the residual grinding amount Δ is workpiece W read in step 100
The grinding wheel radius _RG stored in advance in the grinding wheel diameter storage area 333 of M33 is added, and the grinding wheel head position _GP read in step 102 is subtracted. The value of the remaining grinding amount Δ is stored in the remaining grinding amount storage area 335 of the RAM 33. Delta = By _{(R W + R G) -G} P the residual grinding amount delta is present, the grinding wheel cutting edge circumferential end surface of the grinding wheel 60 interferes with the workpiece W is can grind the workpiece W surface.

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 grinding wheel head 61 stored in. That is, if the grinding condition of the grinding wheel is good, the minimum allowable value Δmin <the remaining grinding amount Δ <the maximum allowable value Δmax
Is 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 calculation of the allowable value may be obtained by multiplying the current feed speed V of the grinding wheel 61 by a predetermined coefficient, or an allowable value corresponding to the feed speed V may be stored in advance. Then, the process proceeds to step 108, in which the remaining grinding amount Δ calculated in step 104 is calculated as the maximum allowable value Δmax calculated in step 106.
It is determined whether 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 grinding wheel head 61 is too fast, and a grinding defect occurs. Judge. Then, if the current feed speed V of the wheel head 61 is not slowed down, it is determined that the grinding wheel is too poor to be ground, and the deceleration process is executed based on the following equation. V ′ = V−β where β = f (V, Δ, Δmax)

If the inequality expression does not hold when the remaining grinding amount Δ is equal to or less than the maximum allowable value Δmax in step 108, the process proceeds to step 112, where the remaining grinding amount Δ is larger than zero and the minimum allowable value calculated in step 106 is determined. It is determined whether it is smaller than Δmin. If the remaining grinding amount Δ is larger than zero and smaller than the minimum allowable value Δmin in step 112, the process shifts to step 114 for achieving the speed changing means. Judge that it takes too much. Then, the acceleration processing is executed based on the following expression, assuming that the grinding can be sufficiently performed even if the current feed speed V of the grinding wheel head 61 is further increased. V ′ = V + α where α = f (V, Δ, Δmin) If the inequality expression is not satisfied even if the remaining grinding amount Δ is equal to or larger than the minimum allowable value Δmin in the above-described step 112, the current remaining grinding amount Δ is appropriate. That is, it is determined that the current feed speed V of the wheel head 61 is appropriate and the grinding is good, and the program is terminated. Further, if the inequality expression does not hold when the remaining amount of grinding Δ is equal to or less than zero in the above-mentioned step 112, the cutting edge of the grinding wheel 60 has not yet been cut into the workpiece W, and it is still before the actual grinding. The feed speed V of the table 61 is maintained. Incidentally, after the processing in step 110 and step 114, in order to determine the speed change, it is substantially several hundred msec.
It takes some time. As described above, in the grinder using the numerical controller of the present invention, calculated the size of the grinding middle of residual grinding amount delta, with respect to the current wheel head feed rate
The maximum and minimum tolerances that will be issued, the appropriate tolerances
Is compared to the value. As a result, the feed speed V of the grinding wheel head 61
Is appropriately changed and set according to the sharpness of the grindstone, so that a stable grinding accuracy is obtained and the grinding time is shortened.

[0012]

The present invention is configured as described above, and the size of the remaining grinding amount during the grinding process is reduced by the current grinding.
Maximum tolerance, which is a reasonable tolerance for the feed rate of the stone bed
By calculating the value and the minimum permissible value and comparing them.
Thus, the feed speed of the grinding wheel head is controlled to be changed so that it is always within a favorable grinding range. Thus, by setting the feed speed according to the sharpness of the grindstone with respect to the workpiece, stable grinding accuracy can be obtained and the grinding time can be shortened.

[Brief description of the 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 diagram showing a relationship between a grindstone diameter and a fixed size value at the time of grinding of the apparatus of the embodiment.

[Explanation of symbols]

 Reference Signs List 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-headstock 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 Steps 100 to 104-Remaining grinding calculation Means Step 106-Allowable Value Calculation Means Steps 110 and 114-Speed Change Means

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G05B 19/416 B24B 47/20 B24B 49/04

Claims (1)

(57) [Claims] 1. A numerical controller for a grinding machine for processing a workpiece by moving a grindstone base on which a grindstone is axially supported with respect to the workpiece at a predetermined feed rate, wherein an outer diameter of the workpiece is measured. A sizing device, a remaining grinding amount calculating means for calculating a remaining grinding amount based on the outer diameter of the workpiece measured by the sizing device and the grinding wheel head position, and a current feed speed of the grinding wheel head. Suitable grinding is available
The maximum allowable value of the remaining grinding amount, which is the limit of the allowable
Whether to calculate the small allowable value from the feed rate and a predetermined coefficient
Alternatively, the grinding stone stored in advance corresponding to the feed speed
Maximum and minimum allowable grinding residual amount according to the feed rate of the table
An allowable value calculating means for calculating from the capacity value, and comparing the remaining grinding amount with the maximum allowable value and the minimum allowable value.
When the remaining grinding amount exceeds the maximum allowable value,
The current feed rate is reduced, and the remaining grinding amount is
When the value is smaller than the capacity value, the speed at which the current feed speed is increased
A numerical controller for a grinding machine, comprising a degree changing means .