JPH01246072A - Grinding surface dressing method for grinding stone - Google Patents

Abstract

PURPOSE:To always maintain the cutting depth of a dresser proper for making it possible to apply surface finish to a workpiece accurately by varying the feeding quantity of the dresser from the last dressing position on the basis of the actual abrasion loss of a grinding stone which has been determined based on the change of the actual radius of the grinding stone before and after grinding the workpiece. CONSTITUTION:The position of the grinding surface of a workpiece 3 is determined along with measuring the dimension of the workpiece 8 by means of a dimension measuring device 20 after grinding the workpiece 3. At the same time the center of a grinding stone 2 in the condition that the grinding has been performed is determined, and the actual radius of the grinding stone 2 is calculated from these positions. The actual abrasion loss of the grinding stone 2 is determined based on the change of the actual radius of the grinding stone 2 before and after grinding the workpiece 3, i.e., for example, directly after dressing and after grinding a specified number of workpiece 3. Then, the increasing quantity of the feed of a dresser 12 from the last dressing position is varied in correspondence with the actual abrasion loss. As a result, the cutting depth of the dresser 12 can be always maintained proper.

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 grindstone used for grinding (hereinafter referred to as a grinding wheel) is marked with a predetermined number of times the number of workpieces that have been ground or the number of times that a predetermined part of the workpiece has been ground is Each time the grinding surface reaches this point, corrections such as reshaping or reshaping are performed to restore the sharpness and shape of the grinding surface.
For example, a dresser using a single stone diamond or the like is placed on the side of a grinding wheel, and the tip of the dresser is placed radially inward of the outer grinding surface of the grinding wheel, in the direction in which they approach each other. The dresser cuts into the outer grinding surface of the grindstone by moving the grindstone linearly in the axial direction, and the outer grinding surface has a predetermined cross-sectional shape. If you also need to make repairs,
For example, a forming dresser with a cross-sectional shape corresponding to the shape to be corrected is sent radially inward of the grinding wheel at a position opposite to the outer grinding surface of the grinding wheel. Make a cut.

Therefore, during the above correction, the feed urn that sends the dresser inward in the radial direction of the grinding wheel is at least equal to the amount of radius reduction of the grinding wheel worn due to the grinding process between the correction and the next correction, and the outer circumference grinding. It is necessary to add an appropriate amount of cut of the dresser in the radial direction of the grindstone so that the surface can recover a predetermined sharpness or shape.

By the way, when using the outer peripheral grinding surface of a grinding wheel, the amount of decrease in the radial dimension of the grinding wheel due to wear relative to the number of workpieces processed generally tends to increase as the diameter of the grinding wheel becomes smaller, even if the grinding surface is not modified. On the other hand, when the dresser is sent inward in the radial direction of the grinding wheel when correcting the grinding surface, the conventional method has been to send the dresser a certain amount further from the position of the dresser at the time of the previous correction.

However, in this case, the grinding surface can be corrected from the beginning of the use of the grinding wheel by adding the above-mentioned appropriate depth of cut to the large reduction due to wear when the radius of the grinding wheel is close to the minimum usable diameter. Unless the radius of the grindstone is close to the minimum diameter, the amount of cut into the grindstone by the dresser becomes unnecessarily large.

For this reason, the present applicant has previously proposed in Japanese Patent Application No. 181245/1988 a correction method in which the feed dog from the previously corrected position of the dresser is increased in accordance with the decrease in the radial dimension of the grinding wheel. In other words, according to this method, at the beginning of use when the amount of decrease due to grinding wheel wear is small, the amount of increase in feed from the position of the dresser at the time of the previous correction is reduced, and the amount of increase in feed is increased as the amount of decrease due to grinding wheel wear increases. Because it can increase
It is possible to maintain the amount of cut into the grindstone of the dresser at an appropriate depth of cut, thereby preventing unnecessary wear and tear on the grinding wheel and the dresser.

(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, the fourth
As shown in the figure, the grinding wheel is corrected every time a certain number of workpieces are processed, and at the time of correction, the feed amount from the dresser position at the previous correction is increased, so that the wear of the grinding wheel progresses normally. As shown in the upper left of Fig. 5, the feed increase amount C is increased appropriately in response to the radius decrease a due to wear between the corrections (indicated by R in the figure). Although the depth of cut of the dresser can be set to an appropriate amount, if the hardness of a particular workpiece is particularly high during the grinding process, or if the chips from grinding are baked onto the surface of the workpiece due to quenching. If abnormal wear occurs on the grinding wheel at point A in the figure, the feed increase amount of the dresser is increased assuming that the radius of the grinding wheel decreases as shown by the broken line in the figure, so that the appropriate amount of cut can be made. As shown by the chain line in the figure, the cut of the dresser may not be made or the amount of cut may be insufficient within the range shown by B in the figure until the time of possible correction, and as a result, there is a possibility that a workpiece with low surface finish accuracy will be produced. was there.

The present invention provides a modification method that advantageously overcomes the above-mentioned improvements.

(Means for Solving the Problems) A grinding surface correction method of a grinding wheel according to the present invention corrects the outer circumferential grinding surface of the grinding wheel by feeding the dresser or the grinding wheel in a direction in which they approach each other, and When increasing the feed amount from the previously corrected position in accordance with the decrease in the radial dimension of the grinding wheel, the position of the machined surface of the workpiece that has been ground by the grinding wheel and the feed state in which the grinding process was performed determining the actual radius of the grinding wheel based on the center position of the grinding wheel, and changing the feed amount based on the actual reduction amount of the grinding wheel determined from the change in the actual radius before and after grinding the workpiece. It is characterized by

(Function) In such a method, as the dimensions of the workpiece are measured after grinding, the position of the machined surface of the workpiece is determined, and at the same time, the position of the machined surface of the workpiece is determined, and at the same time, the grinding state is Find the center position of the grinding wheel, calculate the actual radius (actual radius) of the grinding wheel from these positions, and calculate the actual radius of the grinding wheel.
The actual reduction amount (actual reduction amount) of the grinding wheel is determined from the change before and after grinding the workpiece, that is, for example, immediately after correction and after processing a predetermined number of workpieces. Change the feed increment amount.

Therefore, according to this method, even if the actual reduction amount of the grinding wheel increases significantly due to abnormal wear during predetermined correction, the depth of cut of the dresser can always be kept at the appropriate amount. There is little or no possibility that the workpiece will be produced.

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

FIG. 11 is a configuration diagram showing a cylindrical grinder to which an embodiment of the grinding wheel correction method of the present invention is applied, and in the figure, 1 is a main body, 2 is a grinding wheel, and 3 is a workpiece.

The grinding wheel 2 here is disk-shaped, and is pivotally supported by a grinding wheel head 4, and its center extends in a direction perpendicular to the plane of the paper based on the operation of a grinding wheel drive motor (not shown) on the grinding wheel head 4. Rotates around axis A.

The workpiece 3 here is held at one end by a chuck 5 attached to a main shaft (not shown) provided on the main body 1, and the other end is supported by a tailstock (not shown) to drive the main shaft. Based on the operation of the main shaft drive motor, the workpiece 3 rotates around the central axis B of the workpiece 3, which is aligned with the central axis of the main shaft extending parallel to the central axis A.

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 by a right angle feed table 7 via a parallel feed mechanism 6, and this right angle feed table 7 is also supported by a right angle feed mechanism 8, which is a mechanism similar to the parallel feed mechanism 6.
It is supported by the main body 1 via.

Here, the parallel feed mechanism 6 moves the grindstone head 41 and, by extension, the grinding wheel 2 in the extending direction of its axis A, that is, in the extending direction of the axis B of the workpiece 3, based on the operation of the parallel feed motor 9 that drives the ball screw shaft. Move it back and forth. In addition, the right-angle feed mechanism 8 moves the right-angle feed table 7, and eventually the grinding wheel 2, from a direction perpendicular to the axis B of the workpiece 30, as shown by arrow C in the figure, based on the operation of the right-angle feed motor 10 that drives the ball screw shaft. A perpendicular feed movement approaching the workpiece 3 and a perpendicular return movement in the opposite direction are effected.

The right angle feed table 7 also supports a dresser 12 having a single diamond at its tip via a dresser feed mechanism 11 which is a mechanism similar to the parallel feed mechanism 6, and the dresser feed mechanism 11 supports a ball screw shaft. Based on the operation of the driving dresser feed motor 13, the dresser 12 is caused to move toward the grinding wheel 2 from a direction perpendicular to the axis A of the grinding wheel 2, as shown by the arrow in the figure, and return to the grinding wheel 2 in the opposite direction. bring.

In the figure, 14 indicates a control device for numerical control (NC) of the operation of each of the motors, and this control device 14 includes a human power section 15, a storage section 16, an arithmetic/control section 17, and a processing number counter 18.
Equipped with.

Here, the input unit 15 receives direct operation signals and control program signals from the operation panel 19, and a dimension measuring device 20 that measures the outer diameter dimension of the workpiece 3 during grinding by contacting the workpiece 3 with the probe 20a. A dimension signal is inputted and sent to the calculation/control unit 17, and the calculation/control unit 17 uses a normal C
Pu sends the input control program to the storage unit 16 to be stored therein, and outputs a signal to the drive circuits 21 to 25 of each of the motors based on the control program read from there or the direct operation signal to drive those motors. The machining number counter 18 counts the number of workpieces 3 that have undergone a predetermined grinding process, and sends the machining number to the calculation/control unit 17.

In this embodiment, this cylindrical grinder having such a configuration is made to execute a control program shown in FIG. 2 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 20, 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 number of workpieces counted by the number of workpieces counter 18 is checked, and if the number of workpieces has not reached a predetermined number that requires correction of the outer circumference ground surface 2a, the next step 103 is to proceed to the next step 103, where the workpiece 3 to be machined next is processed. After checking the presence or absence of , the process returns to step 101 again.

In addition, in step 102 above, the number of machining is
If it has reached a predetermined number requiring correction, the process proceeds to step 104, where the feed amount 5D of the dresser 12 from the origin is calculated based on the positional relationship as shown in FIG.

That is, here, the radius r of the workpiece 3 after grinding,
The position F of the machining surface of the workpiece 3 is determined from the position E of the central axis B of the workpiece 3, which is fixed to align with the central axis of the main spindle, and the origin position G of the central axis A of the grinding wheel 2
and the perpendicular feed amount f for grinding the workpiece 3, find the position H of the central axis A of the grinding wheel 2 in the feed state for the grinding process, as shown by the imaginary line in the figure, and calculate these values. From the distance between position F and position H, first, the actual radius R1 of the grindstone 2 at the end of the grinding process is determined. Specifically, the following equation is calculated using the distance between position E and position G.

Rl=Lw −r−f 9 ”' (
1) Next, here, the corrected radius R is calculated by subtracting the appropriate cutting depth of the dresser 12 that can restore the predetermined sharpness or shape to the outer grinding surface 2a of the grinding wheel 2 from the above-mentioned actual radius R4.
2, and from the position I of the outer circumferential grinding surface 2a when the center axis A of the grinding wheel 2 with the corrected radius R2 is located at the origin position G and the origin position J of the tip of the dresser 12, the dresser's Feed amount f. seek. Specifically, position E
The following equation is calculated using the distance Ln between and the position J.

R2=R, -b...(2) fn=
Ln-Rz (3) By performing such calculation, it is possible to obtain the dresser feed amount f, which can ensure the appropriate depth of cut, based on the actual decrease amount of the actual radius R, of the grinding wheel 2. .

Thereafter, in step 105, the dresser 12 is moved from the origin position J at the tip of the grinding wheel 2 with the center axis A at the origin position G by the dresser feed amount f, or the outer peripheral grinding surface 2a By feeding and moving the grinding wheel 2 from a position close to , to the above-mentioned position I, and simultaneously feeding the grinding wheel 2 in parallel, the outer circumferential grinding surface 2a is corrected so as to have an appropriate depth of cut.

Thereafter, by returning to step 103, the planned number of works 3 is continued until the next work 3 is exhausted.
The above steps are repeated until the machining is completed.

Therefore, according to this method, each time a predetermined number of workpieces 3 are processed, the dresser 12
The feed amount from the position at the time of the previous correction of the tip of the grinding wheel 2 is increased, and the feed increase amount is changed in accordance with the actual decrease amount of the radius of the grinding wheel 2. Even if abnormal wear occurs on the grinding wheel 2 at point A and the actual reduction amount of the grinding wheel 2 increases significantly as shown in the figure, the feed amount of the dresser 12 during subsequent corrections is indicated by i in the figure. By increasing the depth of cut, the depth of cut can be set to an appropriate depth of cut, thereby almost or completely eliminating the possibility of producing a workpiece with low surface finish accuracy.

Although the invention has been described above based on the illustrated example, the present invention is not limited to the above-mentioned example. For example, the dresser may be fixed and the grinding wheel may be sent toward the dresser. Furthermore, this method can be easily applied to a surface grinder by actually measuring the position of the machined surface of a flat workpiece upon completion of the grinding process.

(Effects of the Invention) Thus, according to the grinding surface correction method of the present invention, even if the actual reduction amount of the grinding wheel increases significantly due to occurrence of abnormal wear during predetermined correction, the depth of cut of the dresser can always be kept at an appropriate amount. In turn, the possibility of producing workpieces with poor surface finish accuracy can be almost completely eliminated.

[Brief Description of the 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 is a block diagram showing the method of the above embodiment applied to the cylindrical grinder. FIG. 3 is a route map showing the positional relationship between the grinding wheel, workpiece, and dresser in the internal cylinder grinder, FIG. 4 is a flowchart showing the conventional method, and FIG. 5 is a workpiece machining process. It is a relationship diagram showing the relationship between the number and the radius of the grinding wheel. 1... Main body 2... Grinding wheel 2a...
- External grinding surface 3... Work 9... Parallel feed motor 10... Right angle feed motor 12... Dresser 13... Dresser feed motor 14...
NC control device 20... Dimension measuring device Patent applicant Nissan Motor Co., Ltd. Patent attorney Akihide Sugimura Figure 3 Figure 5 - 11th work processing bush

Claims (1)

[Claims] 1. Correct the outer circumferential grinding surface of the dresser or the grinding wheel by feeding them in the direction toward each other, and adjust the feed amount of the dresser from the previous correction position to the distance of the grinding wheel. When increasing the radial dimension in accordance with a decrease in the radial dimension, the grinding wheel is adjusted based on the position of the machined surface of the workpiece that has been ground by the grinding wheel and the center position of the grinding wheel in the feeding state in which the grinding process is performed. A method for modifying a grinding surface of a grinding wheel, characterized in that the actual radius is determined, and the feed amount is changed based on the actual reduction amount of the grinding wheel determined from the change in the actual radius before and after grinding the workpiece.