JPH0360971A - Grinding surface correction method for grinding stone - Google Patents

Abstract

PURPOSE:To perform reliable production of a work with a high surface finishing precision all the time by a method wherein each time a reduction amount of an actual radius due to a work to polish a work exceeds a given value, an outer peripheral grinding surface is corrected. CONSTITUTION:Along with measurement of size available after a grinding work of a work 3 by means of s size measuring device 23, the position of the machining surface of the work 3 is determined and simultaneously a feed amount of a grinding stone 2 when a grinding work is effected is determined. From the position and the amount, the actual radius (real radius) of the grinding stone 2 is calculated by an NC control device 17. When a reduction amount of the actual radius due to a grinding work of the work 3 exceeds a given value, correction of an outer peripheral surface grinding surface 2a is effected by means of a dresser 14. As a result, even when a reduction amount of the grinding stone 2 due to machining of the work 3 is sharply increased due to the occurrence of abnormal wear, a grinding surface 2a can be immediately corrected and therefore, production of the work 3 surface finish precision of which is high can be always effected reliably.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for modifying the outer circumferential grinding surface of a grindstone used for grinding.

(Prior art) The outer circumferential grinding surface of a disc-shaped whetstone used for grinding (hereinafter referred to as the grinding wheel) changes the sharpness and shape of the grinding surface every time the amount of grinding exceeds a certain level. It is necessary to perform corrections such as reshaping in order to restore the surface, but in general, when simply reshaping the cylindrical ground surface, first, for example, a single diamond is used to The dresser is fed at a side position of the grinding wheel radially inward of the grinding wheels in the direction in which they approach each other until the tip of the dresser is positioned radially inward from the outer circumferential grinding surface of the grinding wheel, and then, When cutting the outer grinding surface of the grindstone with the dresser by moving the grindstone linearly in the axial direction, and also reshaping the outer grinding surface into a predetermined cross-sectional shape, for example, A forming dresser with a cross-sectional shape corresponding to the shape to be corrected is sent inward in the radial direction of the grinding wheel at a position opposite to the outer grinding surface of the grinding wheel, so that the dresser cuts the outer grinding surface of the grinding wheel. Let's do it.

Therefore, at the time of the above correction, the amount of feed to send the dresser inward in the radial direction of the grinding wheel is at least the amount by which the radius of the grinding wheel has decreased due to the grinding process between the previous correction and the current correction, and the outer periphery. It is necessary to add the appropriate amount of cutting of the dresser in the radial direction of the grinding wheel to restore the predetermined sharpness or shape to the grinding surface, but the amount of grinding when using the outer peripheral grinding surface of the grinding wheel, For example, the amount of decrease in the radial dimension of the grindstone due to wear relative to the number of workpieces processed generally tends to increase as the diameter of the grindstone becomes smaller, even when the grinding surface is not corrected, as shown by the dashed line S in FIG.

For this reason, the present applicant has previously published Japanese Patent Application Laid-Open No. 64°-27857 (
In Japanese Patent Application No. 62-181245), by increasing the feed amount from the previously corrected position of the dresser in accordance with the decrease in the radial dimension of the grinding wheel, the amount of decrease due to wear of the grinding wheel is small at the beginning of use. The amount of feed increase from the position of the dresser at the time of the previous correction is reduced, and the amount of feed increase can be increased in accordance with the increase in the amount of decrease due to grinding wheel wear, so that the amount of cut into the dresser's grinding wheel is adjusted to the appropriate amount of cut. We proposed a modification method to prevent unnecessary wear and tear on the grinding wheel and dresser by maintaining the grinding wheel and dresser, but with this method, there is a risk that the depth of cut will be insufficient if the workpiece is particularly hard and abnormal wear occurs on the grinding wheel. Because of this problem, the present applicant further proposed in Japanese Patent Application No. 63-71774 that each time the number of workpieces processed reaches a certain number, the dresser is operated at a feed rate determined based on the actual radius of the grindstone determined by measurement. We proposed a modification method that would ensure that the appropriate depth of cut could be maintained.

(Problems to be Solved by the Invention) By the way, the inventors of the present application discovered the following improvements while further researching the above method.

In other words, in the above method, as shown in Fig. 7, the grinding wheel is corrected every time a certain number of workpieces are processed, and at the time of correction, the position of the dresser is adjusted from the position of the dresser at the previous correction according to the actual radius of the grinding wheel. Because the feed rate is increased, even if abnormal wear occurs on the grinding wheel during machining of the above-mentioned fixed number of workpieces, for example immediately after correction, correction will not be made until the fixed number of workpieces have been processed. There was a possibility that the surface finish accuracy of the workpiece machined between the occurrence of abnormal wear and the time of grinding wheel correction was insufficient.

The present invention provides a modification method that advantageously solves the problems of the conventional methods described above.

(Means for Solving the Problems) The method for modifying the grinding surface of a grinding wheel of the present invention is such that when modifying the outer circumferential grinding surface of the grinding wheel by sending the dresser or the grinding wheel toward each other, The actual radius of the grinding wheel is determined based on the position of the processed surface of the workpiece that has been ground by the grinding wheel and the feed rate of the grinding wheel when the grinding process is performed, and the reduction in the actual radius due to the grinding process of the workpiece is calculated. Each time the amount exceeds the predetermined amount,
The present invention is characterized in that the outer circumference ground surface is corrected.

(Function) In this method, as the dimensions of the workpiece are measured after grinding, the position of the machined surface of the workpiece is determined, and along with this, the position of the grinding wheel when the grinding process is performed is determined. The feed amount is determined, and the actual radius (actual radius) of the grinding wheel is calculated from the position and amount, and when the amount of decrease in the actual radius due to grinding of the workpiece exceeds a predetermined amount, the outer circumferential grinding surface is corrected.

Therefore, according to this method, even if the amount of reduction in the grinding wheel due to workpiece processing increases significantly due to the occurrence of abnormal wear, the grinding surface can be corrected immediately, producing workpieces with high surface finish accuracy. can always be carried out reliably.

(Example) Hereinafter, an example of the present invention will be described in detail based on the drawings.

FIG. 1 is a configuration diagram showing a numerically controlled (NC) cylindrical grinder to which an embodiment of the grinding wheel correction method of the present invention is applied. In the figure, 1 is the main body, 2 is the grinding wheel, and 3 is the workpiece. show.

The grinding wheel 2 here is disk-shaped, is pivotally supported by a grinding wheel head 4, and is driven by the operation of a grinding wheel drive motor 5.
It rotates around its central axis 01 extending in a direction perpendicular to the plane of the paper.

The workpiece 3 here is held at one end by a chuck 6 attached to a main shaft (not shown) provided on the main body (2), and the other end is supported by a tailstock (not shown) to drive the main shaft. Based on the operation of the spindle drive motor, the workpiece 3 rotates around the center axis 02 of the workpiece 3, which is aligned with the center axis of the main spindle extending parallel to the center axis 01.

The grindstone head 4 that supports the grinding wheel 2 has a drive mechanism that moves a ball nut screwed into it by rotation of a ball screw shaft, and a guide mechanism that guides the movement of a slider fitted there with a linear guide. It is supported via a parallel feed mechanism 7 to a right angle feed table 8, which also has a right angle feed mechanism 9, which is a mechanism similar to the parallel feed mechanism 7.
It is supported by the main body 1 via.

Here, the parallel feed mechanism 7 moves the grindstone head 4, and eventually the grinding wheel 2, in the direction in which the axis 01 extends, that is, the workpiece 3, based on the operation of the parallel feed motor 10 that drives the ball screw shaft.
reciprocating in the extending direction of axis 02. Further, the right angle feed mechanism 9 operates the right angle feed table 8 and the grinding wheel 2 based on the operation of the right angle feed motor 12 that drives the ball screw shaft 11.
As shown by the arrow in the figure, a right-angled feed movement approaching the work 3 from a direction perpendicular to the axis 02 of the work 3 and a right-angled return movement in the opposite direction are brought about.

The right-angle feed table 8 also supports a dresser 14 having a single-shot diamond at its tip via a dresser feed mechanism 13 which is a mechanism similar to the parallel feed mechanism 7, and the dresser feed mechanism 13 supports a ball screw shaft 15. Based on the operation of the dresser feed motor 16 that drives the dresser 14, the dresser 14 is moved to approach the grinding wheel 2 from a direction perpendicular to the axis ○ of the grinding wheel 2, as shown by arrow E in the figure, and returned in the opposite direction. bring about movement.

In the figure, reference numeral 17 indicates an NC control device for each of the motors, and this control device 17 includes a human power section 18, a storage section 19, an arithmetic/control section 20, and a processing number counter 21.

Here, the input unit 18 receives direct operation signals and control program signals from the operation panel 22, and a dimension measuring device 23 that measures the outer diameter dimension of the workpiece 3 during grinding by contacting the workpiece 3 with the probe 23a. A dimension signal is inputted and sent to the calculation/control unit 20, and the calculation/control unit 20 uses a normal C
The control program manually executed by the PU is described below.1. Based on the control program or direct operation signal read from there, signals are output to the drive circuits 24 to 28 of each of the motors to control the operation of the motors, and the machining number counter is 2) counts the number of workpieces 3 for which a predetermined grinding process has been completed, and sends the number of processes to the arithmetic/control unit 20; In addition, the above-mentioned feed motor 10.
12 and 16 are each equipped with a rotary encoder, and each feeding amount is fed back to the drive circuits 24 to 26 to enable highly accurate feeding.

For example, when performing normal machining using this cylindrical grinder having such a configuration, the control program shown in FIG. 2 is repeatedly executed to grind a large number of workpieces 3.

That is, here, first in step 101, the workpiece 3 is ground. This grinding process is performed using instructions for the rotational speed of the workpiece 3, the rotational speed of the grinding wheel 2, the feed amount and feed rate of the parallel and perpendicular feed movement of the grinding wheel 2, and the dimensions from the dimension measuring device 23, which are included in the control program. Based on signal feedback and the like, the grinding is performed using the outer circumferential grinding surface 2a of the grinding wheel 2 so that the outer circumferential surface 3a of the workpiece 3 has a predetermined outer diameter and a predetermined finishing accuracy.

In the next step 102, the grinding wheel 2 at a predetermined return position is
The distance between the center axis O7 and the workpiece center axis 02, and the radius r of the workpiece 3 after grinding based on the above dimension signal
Then, from the perpendicular feed amount from the return position to the end of the grinding process in step 101, calculate the actual radius R of the grinding wheel 2 at the end of the grinding process using the following formula, R=L- r-A The actual radius R and the actual radius at the time of the last correction of the grinding wheel (if the correction has not been made - times, the actual radius measured at the beginning of use)
Calculate the difference between the two and calculate the amount of decrease in the actual radius due to repeated machining of the workpiece after correction.

Here, in the next step 103, it is determined whether the actual radius reduction amount of the grinding wheel 2 exceeds a predetermined amount a that requires recovery of the sharpness and shape of the grinding surface, and the reduction amount is determined to be a predetermined amount. If the predetermined amount a has not been exceeded, this program is terminated, but if the predetermined amount a has been exceeded, the process proceeds to step 104 and the outer peripheral grinding surface 2a of the grindstone 2 is corrected.

This correction is based on the center axis 0 of the grinding wheel 2 at the return position.
1 and the tip of the dresser 14 at the predetermined return position, the above-mentioned actual radius R, and the appropriate depth of cut that can restore the predetermined sharpness or shape to the outer grinding surface, the following formula % formula % is used. This is done by sending the dresser 14 by the determined dresser feed amount B, and when this correction is completed, this program ends.

By repeatedly executing the above program, if there is no abnormal wear on the grinding wheel, as shown by the two-dot chain line in Figure 3,
The number of workpieces machined between the correction when the actual radius of the grinding wheel is large and the next correction is significantly greater than the number of workpieces processed between the correction and the next correction when the actual radius of the grindstone is small, and therefore , as shown by the solid line T in Fig. 6, the grinding wheel life can be extended compared to the conventional method (indicated by the broken line U in the figure) in which correction is made every time a certain number of pieces are processed. If abnormal wear occurs on the grinding wheel due to a particularly high temperature or seizure of chips during cutting, as shown by the dashed line in Fig. 3 (abnormal wear at point J), the abnormal wear causes the grinding wheel to Since the correction is made immediately at the point in time when the actual radius decrease exceeds the predetermined amount a, the sharpness and shape of the outer circumferential ground surface are prevented from deteriorating beyond the allowable level, and the surface finish of the workpiece is improved. Deterioration in accuracy can be reliably prevented.

Incidentally, due to the feeding of the dresser 14, the actual radius decrease amount for each correction becomes a constant value C as shown in FIG.

When high-precision machining is performed using the cylindrical grinder, for example, a control program shown in FIG. 4 is repeatedly executed to grind a large number of workpieces 3.

This program has a step 105 inserted between steps 101 and 102 of the program shown in FIG. If it has not been done, the process proceeds to step 102; if it has been done, the process proceeds to step 104 to perform the next grindstone correction.

By executing such a program, if there is no abnormal wear on the grinding wheel, it is possible to make corrections every time the workpiece is machined, as shown by the solid line in Figure 3, and to maintain high precision at all times. The correction method is the same as before,
The amount of decrease in the actual radius for each correction increases as the actual radius becomes smaller, as shown by g and c in FIG. ), On the other hand, if abnormal wear occurs on the grinding wheel, as shown by the broken line in Fig. 3, (abnormal wear occurs at time k), correction is made immediately at time k, where the number of machining operations is less than h. The machining accuracy of the workpiece can be reliably maintained at a high level of accuracy.

FIG. 6 shows a conventionally used hydraulic grinding machine, in which the parallel feed mechanism 7, the right angle feed mechanism 9, and the dresser feed mechanism 13 are operated by hydraulic cylinders 29, 30, .
31.

In such a grinding machine, the right angle feed mechanism 9 and the dresser feed mechanism 13 are each equipped with a linear sensor 32 for detecting the feed amount.
33, the correction method of the present invention can be carried out in the same manner as in the previous example, and therefore the same effects as described above can be brought about.

Although the above has been explained based on the illustrated example, it goes without saying that the present invention is not limited to the above-mentioned example.

(Effects of the Invention) Thus, according to the method of the present invention, even if the amount of reduction in the grinding wheel due to workpiece processing increases significantly due to abnormal wear, the grinding surface can be corrected immediately, and the surface finishing accuracy can be improved. High-quality workpieces can always be produced reliably.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing a cylindrical grinder to which an embodiment of the grinding surface correction method of a grinding wheel of the present invention is applied, and FIG. 2 shows a control program for causing the cylindrical grinder to execute the method of the embodiment. Flow chart, FIG. 3 is a relationship diagram showing the relationship between the number of workpieces processed and the radius of the grinding wheel, FIG. 4 is a flow chart showing a control program for causing the cylindrical grinder to execute another embodiment of the present invention, and FIG. The figure is a relationship line diagram roughly showing the relationship between the number of workpieces processed and the diameter of the grinding wheel. Figure 6 is a configuration diagram showing another cylindrical grinder to which this invention can be applied. Figure 7 is a flow chart showing the conventional method. It is.

Claims (1)

[Claims] 1. When modifying the outer peripheral grinding surface of a dresser or a grinding wheel by feeding them toward each other, the position of the machined surface of the workpiece that has been ground by the grinding wheel The actual radius of the grinding wheel is determined based on the feed rate of the grinding wheel when the grinding process is performed, and each time the amount of decrease in the actual radius due to the grinding process of the workpiece exceeds a predetermined amount, the outer periphery grinding is performed. A method for modifying a grinding surface of a grinding wheel, the method comprising modifying the surface.