JP2565968B2 - Forming method of grinding wheel in thread groove grinding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a thread groove grinding process for controlling a NC wheel to form a grinding wheel in which a grinding wheel shaft is inclined with respect to a lead angle of a screw groove for grinding. To a method for forming a grinding wheel in a car.

(Prior Art) Conventionally, when grinding is performed by NC control with a grinding wheel in which a grindstone of a ball screw has a thread groove inclined with respect to a lead angle of the object, the grindstone shape of the grinding wheel is Since the grindstone shaft is tilted, it does not match the right-angled cross-sectional shape of the screw groove and is complicated, and the grinding wheel wears the outer diameter and the grindstone shape with the progress of the grinding process and changes minutely, resulting in high accuracy. In addition, the workpiece cannot be ground. For this reason, it is necessary to re-form the grinding wheel in accordance with this minute change so that the grinding wheel has a predetermined grinding wheel shape, and the following method can be considered as a molding method of this type.

First, a rotatable dresser for forming the grinding wheel is brought into contact with a positioning pin which is set at the center of rotation, and the dresser is set at a position of a predetermined turning radius. Thereafter, the grinding wheel shape is formed by bringing the grinding wheel into contact with the dresser by NC control and rotating the dresser while moving in the left-right and front-rear directions. At this time, the tip of the dresser is also slightly worn by molding the grinding wheel, which adversely affects the molding of the grinding wheel shape. In order to eliminate this adverse effect and form a grinding wheel having a predetermined grinding wheel shape, the number of times of grinding the workpiece is set corresponding to the allowable wear amount of the grinding wheel. The turning radius increased due to the wear of the dresser is corrected to a predetermined turning radius by adjusting the movement of the dresser so that it comes into contact with the positioning pin set at the opposite position on the turning center of the dresser every predetermined number of times of grinding. Then, the grinding wheel is formed.

Therefore, in this type of method, the positioning pin is set at an opposing position on the center of rotation of the dresser while repeatedly rotating the dresser, and the dresser is moved so as to abut the positioning pin. Must be corrected, and the work becomes complicated, and the device is complicated and difficult to perform automation. Further, this correction work needs to be repeated every time the grinding wheel is formed, which further complicates the work. Further, since the positioning pin is set each time, an error may occur in the mounting of the positioning pin each time, and a uniform grindstone shape may not be obtained, and in order to reduce this mounting error, the mounting of the positioning pin However, there is a problem in that the work efficiency of the grinding wheel forming process decreases, the time required for grinding the workpiece cannot be shortened, and it is difficult to improve productivity.

(Problems to be solved by the present invention) The present invention eliminates such conventional inconvenience, detects the wear amount of the dresser tip without correcting the turning radius of the dresser, and corrects the grinding wheel position by NC control. While forming the grinding wheel by turning the dresser with a predetermined turning radius, the grinding wheel can be easily formed automatically and the thread groove of the workpiece can be ground with high precision. An object of the present invention is to provide a method for forming a grinding wheel in a thread groove grinding process that can reduce the time for forming a wheel.

Further, the grinding process of the workpiece with the grinding wheel and the forming process of the grinding wheel are controlled in accordance with the wear amount of the dresser by the NC control, and a series of grinding processes is performed by continuously performing these processes. An object of the present invention is to provide a method for forming a grinding wheel in thread groove grinding that can reduce the time required.

(Means for Solving the Problem) In order to achieve such an object, a method for forming a grinding wheel in thread groove grinding according to the present invention includes a method of tilting a wheel axis with respect to a lead angle of a thread groove of a workpiece. A grinding wheel that grinds a thread groove by abutting on the tip of the dresser, and the grinding wheel abuts on the dresser while turning the dresser at a predetermined turning center set in front of the dresser tip. As described above, a method of correcting the position of the grinding wheel by NC control in accordance with the wear amount of the dresser tip to form the grinding wheel into a predetermined grindstone shape, which is coaxially rearward from the dresser tip. When a distance l to a detected portion provided on the dresser is measured and a reference point is set on the dresser axis farther than the turning radius of the detected portion, and the tip end of the dresser is at a position facing the reference point. From the reference point to the dresser tip The distance L1 is measured, the distance L2 from the reference point to the detected portion when the dresser is turned by 180 ° from the position is measured, and the turning radius R of the dresser tip is R = (L1-L2 -L) / 2, after grinding the grinding wheel by the dresser, the distance L1 'from the reference point to the worn dresser tip when the dresser tip is in a position facing the reference point Is measured, the wear amount a of the dresser tip is detected from a = L1'-L1, and the actual turning radius R'of the dresser tip is R '= R.
It is characterized in that it is detected from + a and the position of the grinding wheel is corrected corresponding to this execution radius R '.

In addition, after the grinding wheel is molded by the grinding wheel molding method of the invention, the grinding wheel is moved to a grinding position, and the position and the feed amount of the grinding wheel are corrected corresponding to the wear amount of the dresser tip. While grinding the work piece while the grinding wheel is worn and the processing accuracy of the work piece deteriorates, the grinding wheel is moved to a grinding wheel forming position corresponding to the wear amount of the dresser tip portion and a predetermined position is set. It is characterized in that it is formed into a grindstone shape, and the forming process of the grinding wheel and the grinding process of the workpiece are continuously performed.

(Operation) The method for forming a grinding wheel according to the present invention comprises:
The wear amount of the dresser tip portion is detected at a predetermined grinding wheel forming position. Next, the position of the grinding wheel is adjusted according to this wear amount.
The NC wheel is corrected in the front-rear direction and the left-right direction, and the grinding wheel is controlled to be brought into contact with the dresser that turns with the constant turning radius, so that the grinding wheel is formed into a predetermined grinding wheel shape.

Further, in the grinding wheel forming method of the present invention, a distance l from the dresser tip portion to the detected portion is measured. Then, the distance L1 from the reference point to the dresser tip is measured. Next, the dresser is turned 180 ° to measure the distance L2 from the reference point to the detected portion, and the turning radius R before processing is detected from the measured distances L1, L2, l. After that, the workpiece is ground and the deformation due to the wear of the grinding wheel is formed to wear the dresser tip. The distance L1 'from the reference point to the dresser tip portion, which increases due to this wear, is measured, and the wear amount a of the dresser tip portion is detected from L1' and L1. a is added to detect the working radius R'of the dresser tip, and the grinding wheel position is corrected in correspondence with the working radius R '.

Further, after the grinding wheel is molded by the method for molding a grinding wheel of the invention, the grinding wheel is moved to a grinding position, and the position of the grinding wheel is made to correspond to the wear amount of the dresser tip and the wear amount of the grinding wheel. Then, the feed amount is corrected and grinding is performed so that the thread groove of the workpiece has a predetermined shape. When the grinding wheel is worn due to grinding and the processing accuracy of the workpiece is lowered, the grinding wheel is moved to the grinding wheel forming position corresponding to the wear amount of the dresser tip portion, and the grinding wheel forming method according to the invention is used. It is formed into a predetermined grindstone shape. The forming process of the grinding wheel and the grinding process of the workpiece are continuously and sequentially repeated.

(Example) A detailed description will be given below with reference to FIGS. 1 to 3 showing an apparatus for carrying out the present invention.

The apparatus is a three-axis NC control grinder 1 for internally grinding the thread groove of a nut X of a ball screw which is a workpiece. This is the lead angle α of the thread groove of the nut X as shown in the first illustration.
Grindstone axis 2 tilted horizontally by a predetermined angle θ
Further, a grindstone 3 is provided, and a grindstone base 6 is provided which is movable in the left-right and up-down directions in the drawing via a vertical feed table 4 and a horizontal feed table 5. A headstock 7 that holds the nut X at a position facing the grinding wheel base 6 and rotates at a predetermined rotation number according to the lead angle α of the nut X and the vertical feed of the grinding wheel 3 is provided in the vicinity of the headstock 7. A dresser swivel base 9 for holding and swiveling the dresser 8 for forming the grinding wheel 3 is provided in parallel. A sensor unit 10 facing the dresser swivel base 9 to measure the amount of wear of the dresser 8 by moving it in the left and right vertical feed directions is provided with a sensor unit 10 which is movable in the front and rear lateral feed directions on the dresser swivel base 9 side of the horizontal feed table 5. A magnetic scale 11 is provided. An NC controller (not shown) is provided which receives a measurement value input from the magnescale 11 and connects the grindstone base 6 and the dresser swivel base 9 to control them.

The dresser swivel base 9 holds the dresser 8 and receives an input signal from the control device to swivel the dresser 8 horizontally around the swivel center line O, as shown in the second diagram. And a ball 13 for measuring a dresser turning radius, which is a detected portion, is provided coaxially behind the dresser 8.

Next, a method for carrying out the present invention will be described according to the operation of the apparatus having the above-mentioned configuration.

First, as shown in FIG. 2, the dresser 8 has a turning radius R and is held by the turning holding part 12, the turning holding part 12 is parallel to the axis of the magnescale 11, and the tip end of the dresser is the sensor part 10.
Initially set to the L1 measurement position opposite to.

Next, attach the magnescale 11 to the turning center line O of the dresser 8.
Move to the opposite position of the line. Magnescale at this position
The sensor unit 10 of 11 is projected and brought into contact with the tip of the dresser 8 to measure the vertical feed distance L1 from the reference point to the dresser tip at the L1 measurement position. After the measurement, the sensor unit 10 is housed, the swivel holding unit 12 of the dresser swivel base 9 is swung 180 ° around the swivel center line O line from the L1 measurement position, and the measuring ball 13 of the dresser 8 is a sensor of the magnescale 11. It is held at the L2 measurement position (shown in phantom in FIG. 2) facing the section 10. Once again, the sensor unit 10 of the magnescale 11 is projected and brought into contact with the measuring ball 13 so that after the turning from the reference point.
The vertical feeding distance L2 to the measuring ball 13 at the L2 measuring position is measured.

The distance l from the tip of the dresser to the measuring ball 13 is measured in advance and input to the NC controller, and each measured value L
Input 1, L2 to the NC controller after measurement, and set the turning radius R of the dresser tip at the initial setting to R = (L1-L2-l) / 2
It is calculated from the formula

In the grinding wheel 3, the shape of the grindstone is deformed by the grinding of the workpiece X, and the thread groove of the workpiece X cannot be ground in a predetermined shape. This limit is set based on the number of grinding times of the workpiece, and when the grinding of the workpiece X by the same grinding wheel 3 reaches a predetermined number of grindings, the grinding wheel 3 is shaped by the dresser 8.

Since the dresser tip is also worn by molding the grinding wheel 3, the vertical feed distance L1 'from the reference point to the worn dresser tip is measured as shown in FIG. The L
Since 2, l is constant as long as the turning radius L of the turning holding portion 12 is not changed, L1 'increased by wear is measured and input to the control device and the wear amount a of the tip of the dresser is a = L1'-
Calculate from L1. From this wear amount a, the actual turning radius R'of the dresser tip is obtained from R '= R + a and input to the control unit.

After detecting the execution radius R ', the magnet scale 11 is moved to the initial position and the swivel holder 12 is returned to the L1 measurement position. After that, the grinding wheel 3 of the grinding wheel base 6 is rotated and brought into contact with the tip of the dresser 8. The grinding wheel head 6 is controlled by the NC controller according to the difference between the execution radius R ′ and the set turning radius R, that is, the wear amount of the dresser tip.
Moves left and right and front and back on the vertical feed table 4 and the horizontal feed table 5 to correct the position of the grinding wheel 3, and the dresser swivel base 9 responds to the correction of the position of the grinding wheel 3 to start turning the dresser 8 in a predetermined manner. Turn from the position to the turn end position. In this way, the grinding wheel 3 is formed into a predetermined grinding wheel shape by turning the dresser 8 while correcting the grinding wheel position in accordance with the wear amount of the dresser tip portion.

After the grinding wheel 3 has been molded, the grinding wheel base 6 is moved to a grinding position facing the ball screw X set on the headstock 7. At this time, the grinding position of the grinding wheel 3 which changes due to the wear of the dresser tip portion and the wear of the grinding wheel 3 is input to a predetermined grinding program to correct the vertical feed and the lateral feed of the grinding wheel 3 to correct the ball screw. The X thread groove is ground into a predetermined shape.

Therefore, with the reference point kept constant, the position of the dresser 8 is detected by the magnescale 11, and the grinding wheel position is corrected in accordance with the wear radius R ', that is, the wear amount a, to form the grinding wheel 3, so that the dresser 8 is formed. The initial setting can be set to a rough position, and a uniform grindstone shape can be easily obtained without complicated work as in the conventional case, and the molding efficiency can be improved.

Further, by displaying the detected wear amount a, it is possible to easily grasp the replacement time of the dresser 8, so that the quality can be improved.

(Effect) As is apparent from the above description, the present invention detects the wear amount of the dresser tip without correcting the turning radius of the dresser and corrects the grinding wheel position in the front-back and left-right directions by NC control. The grinding wheel can be formed easily by automatically contacting the dresser by turning the dresser at a predetermined turning radius regardless of the wear amount, and the thread groove of the work piece can be highly accurately formed. It is possible to provide a grinding wheel forming method in thread groove grinding, which can shorten the time for forming the grinding wheel to be ground.

In addition, the wear amount of the dresser tip is guided by measuring the distance from the reference point to the dresser tip and measuring the distance to the detected part provided coaxially behind the dresser tip by turning it. The initial setting position is good and the mounting work is easy, and after the initial setting, the wear amount of the dresser tip can be easily detected by measuring only the distance from the reference point to the dresser tip.

In addition, the grinding of the work piece and the forming of the grinding wheel are NC
By controlling the amount of wear of the dresser and the amount of wear of the grinding wheel in accordance with the control, and performing these processes continuously, the time required for a series of grinding processes can be shortened.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an apparatus which is an example of the embodiment of the present invention,
FIG. 2 is a partial explanatory view of the apparatus, and FIG. 3 is a partial explanatory view of the dresser tip portion after wear. 2 …… Whetstone axis, 3 …… Whetstone wheel 8 …… Dresser, 13 …… Detected part α …… Lead angle of thread groove θ …… Inclination angle of grindstone axis X …… Workpiece L …… Turning radius L1 ...... Longitudinal feed distance to the dresser tip L2 …… Vertical feed distance to the dresser detected area R …… Turning radius of the dresser default R ′ …… Dresser execution radius l …… Dresser tip and detected area Distance a ... Wear amount of dresser tip

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yukihiro Nishihara 1-10-1 Shin-Sayama, Sayama-shi, Saitama Honda Engineering Co., Ltd. (56) References JP-A-62-228370 (JP, A) JP-A-SHO 61-173858 (JP, A) Actual development Sho 58-4352 (JP, U)

Claims (2)

(57) [Claims] 1. A grinding wheel that grinds a thread groove by inclining a grindstone shaft with respect to a lead angle of the thread groove of a workpiece is brought into contact with the tip of the dresser and set in front of the tip of the dresser. While turning the dresser around a predetermined turning center, the position of the grinding wheel is corrected by NC control corresponding to the wear amount of the dresser tip so that the grinding wheel comes into contact with the dresser. A method of forming into a predetermined grindstone shape, wherein a distance l from the dresser tip portion to a detected portion provided coaxially behind the dresser is measured, and the distance l is set on the dresser axis farther than the turning radius of the detected portion. When a reference point is set, the distance L1 from the reference point to the dresser tip is measured when the dresser tip is at a position facing the reference point, and the dresser is turned 180 ° from the position. The distance L2 from the reference point to the detected part After determining the turning radius R of the dresser tip from R = (L1-L2-l) / 2 and grinding the grinding wheel by the dresser, the dresser tip is located at a position facing the reference point. The distance L1 'from the reference point to the worn tip of the dresser at a given time is measured, the wear amount a of the tip of the dresser is detected from a = L1'-L1, and the working radius R of the tip of the dresser is measured. ′ Is detected from R ′ = R + a, and the position of the grinding wheel is corrected according to the radius of gyration R ′. A method for forming a grinding wheel in thread groove grinding. 2. After the grinding wheel is molded by the grinding wheel molding method according to claim 1, the grinding wheel is moved to a grinding position, and the position of the grinding wheel is adjusted corresponding to the wear amount of the dresser tip. When the grinding wheel is worn while the grinding wheel is worn and the processing accuracy of the workpiece is lowered, the grinding wheel is moved to the grinding wheel forming position corresponding to the wear amount of the dresser tip. A method for forming a grinding wheel in thread groove grinding, which comprises moving to a predetermined shape of a grinding wheel, and continuously performing the forming processing of the grinding wheel and the grinding processing of a workpiece.