JPH0790420B2 - Tooth profile grinding device, cutting margin distributing device therefor, and cutting margin distributing method - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a tooth profile grinding machine and an allowance distribution device therefor.

Conventional technology and its problems Grinding of cylindrical gears (spur teeth or helical gears) is a precision work, and is generally adopted when machining gears of aircrafts and instruments that require maximum precision in tooth profile and position. It In grinding for forming a tooth profile in general terms, the peripheral edge of a grinding wheel is shaped into a groove between two adjacent teeth. Rotate the grindstone to generate the required surface speed on the grinding surface, insert the grindstone's peripheral edge into the groove, and move laterally in the relative axial direction. At the same time, feed from end to end to grind.

If the gear is a spur gear, the grinding wheel is placed so that its axis is at a right angle to the axis of the gear and the gear is fixed so that it does not rotate during lateral movement in the axial direction. If the gear is a helical gear, the grinding wheel is set to the required screw angle and the gear is given controlled rotation in conjunction with axial advance to create a twist.

The grinding process of finishing the hardened gear shape presents new problems. In gear tooth profile grinding, for economic reasons, it is desirable to always apply equal amounts of material from both sides of the tooth groove. However, if the gear teeth are hardened, this becomes a more important requirement. If the grinding wheel is not exactly centered in the groove, excess material is removed from the tooth flank on the other side to ensure proper grinding of the tooth flank on the one side. In some cases, the hardened layer is removed from the tooth surface on the other side.

The centering of the grinding wheel in the tooth groove is called "stock dividing". In the past, during the distribution of the cutting margin, it was confirmed by the operator visually and / or by the processing noise that the first simultaneous contact between the grinding wheel and both sides of the tooth groove occurred.

In the past, relating the rotation of a gear to the relative axial lateral movement between this gear and the grinding wheel has been accomplished by a precisely ground leading bar and nut mechanism, or a so-called sine bar and driven mechanism. , Mechanically, for example as described in US Pat. No. 3,440,769. This U.S. patent additionally shows means for adjusting the sine bar in order to precisely control and rotate the gears for the purpose of performing the shaving distribution operation.

It is also common practice to mechanically perform indexing rotation of the gear to be machined by using an indexing plate that has exactly the same number of teeth as the number of gear teeth and is notched at equal intervals. It was done on a regular basis. The indexing plate is connected to rotate with the gear, and the indexing plate is advanced exactly by one indexed tooth, and the locking piece is installed in the notch. Therefore, the gear is rotated and locked in place.

DISCLOSURE OF THE INVENTION In the present invention, the position of the arc is accurately predetermined up to a fraction of a second, to rotate the gear to a position programmed or programmed by the computer, and also predetermined. In order to rotate from a position to another arbitrary position with the same accuracy as above, an electric motor means to which numerical control by a computer (CNC) is applied can be used. In this way, the indexing can be controlled by the computer with an accuracy never obtained in the past.

Furthermore, the rotational movement of the gear, which is temporally related to the lateral movement in the axial direction between the gear and the grinding wheel, can be controlled by such lateral movement in the axial direction. Lateral movement of the gear or grindstone in a direction parallel to the axis of the gear can be achieved by axially traversing the gear and time to produce the desired helix angle by appropriately programming the electrical pick-up means, i.e. the computer. Is sensed by electrical pick-up means which operate the drive motor to rotate in relation to. More specifically, the instantaneous angular position of the gear is thus related to the relative position of the gear and the grinding wheel with respect to the relative lateral movement of the gear in a direction parallel to the axis of the gear with maximum precision.

In this way, the rotation, which is time-related to the indexing and the relative lateral movement of the gears, can be fully effected by numerical control by the computer, and a mechanically operated indexing plate, And the leading bar or sign bar is no longer needed.

According to the invention, a numerical control by a computer (CNC) for the rotation of gears provides an automatic gear grinding machine with which it is possible to distribute the cutting margin with a precision and speed that has hitherto been unattainable. Combined with additional structure for

In this way, a new CNC gear grinding machine is provided which can reduce set-up time and distribute cutting margins with improved accuracy.

Since the gear to be machined has already been gear cut, it is necessary to position the grinding wheel in the groove so that an equal amount of excess material is removed on both sides of the grinding wheel. In the past, this was done manually by the operator. It was also believed that the time required to do this was part of the set-up time when mounting each individual gear to be machined.

The present invention, as described above, improves a CNC gear grinding machine so that it can automatically distribute the shavings to reduce set-up time and increase productivity.
Further, this distribution of the shaving margin is more accurate than was possible with the conventional manual method, and the average polishing time can be practically shortened. Finally, the distribution operation of the shavings firstly provides the possibility of sensing the angular width of the peripheral edge of any desired number of tooth spaces, and it is possible to determine the average value of such widths, In addition,
For all indexed positions of the gear, the appropriate shaving distribution position for the gear can be determined.

The above is achieved by having one sensing probe that can be moved into or out of the gear groove and is accurately positioned with respect to the position of the grinding wheel. In the simple case, the center of the probe is at the same angular position as the grindstone on the periphery of the gear. The probe chip may be a contact type or a non-contact type. Excellent results are obtained with the contact trigger (TT) probe.

One probe with a spherical tip of a size substantially smaller than the space between the tooth flanks on both sides of the tooth groove,
Position in tooth groove as above. The gear is rotated in one direction until one of the tooth flanks activates the probe, and the angular position (Oa degree) of the gear at that time is recorded in the computer. The gears are then rotated in the opposite direction and continued to rotate until the adjacent flank activates the probe. The angular position (Ob) of the gear at this moment is recorded in the computer.
The difference between the two rotational positions, Oa-Ob, is calculated and, under computer control, the gear is driven in the opposite direction for an arc length equal to half this value. At this point, the center of the spherical tip and, accordingly, the grinding wheel is centered with respect to the groove, resulting in an accurate distribution of the cutting margin.

The position of the probe may be further than the position of the grinding wheel if the information about this position is recorded in the computer. Similarly, the position of the probe in the axial direction of the gear is also supplied to the computer, and if the gear is a helical gear, the probe sphere is located in a helical position relative to the grindstone.

In order to achieve a more accurate distribution of the cutting margin, it is possible to determine values corresponding to Oa degrees to Ob degrees for any number of tooth spaces. A theoretical value for the position of the tooth flank, not only for calculating the average value of the difference corresponding to Oa degree-Ob degree, but also taking into account the highly accurate indexing achieved by the gear positioner of the computer control. The variation from is also calculated.

Then, grinding is started in the last detected groove.
In order to grind the other teeth, further gearing is required, which is based on the average value of the difference corresponding to the degree of Oa-Ob and the correct and appropriate angular position based on the possible variations in the tooth-to-tooth spacing. Will be indexed.

If the probe cannot be conveniently mounted in the plane of the grinding wheel or in a helical arrangement, the angular displacement between the wheel and the probe is recorded on the computer. Since this is a constant value, the measured value for the distribution of all the cutting margin by the probe can be corrected by the value of the constant angular displacement between the probe and the grindstone. However, this is done automatically based on accurate indexing by the computer.

Embodiment First, FIG. 1 shows the position of the grinding wheel W in the groove of the gear G in the middle of the teeth Ta and Tb. The unpolished tooth is shown by the solid line. Further, the shaped peripheral portion of the grindstone is shown by dotted lines Wa and Wb. The material of the gear teeth between the solid line and the dotted lines Wa and Wb is such that the gear G and the grindstone W move laterally relative to each other in the direction parallel to the axis of the gear and pass only once. It is the cutting edge that should be removed from the surface. Proper distribution of the cutting margin is achieved if the depths of the parts between the unpolished contours on the tooth flanks of the teeth Ta and Tb and the dotted lines Wa and Wb are equal on both sides of the tooth space.

If the gear is a helical gear, set the grinding wheel to the helix angle of the gear. In addition, the relative lateral movement between the gear and the grinding wheel in the axial direction of the gear is determined by the relative rotation between the gear and the grinding wheel synchronized with the lateral movement in order to conveniently create the required twist by the rotation of the gear. Is achieved by

Furthermore, each tooth groove is ground separately so that after each passage of the wheel the gear is rotated for indexing in order to center the other tooth groove with the wheel.

Conventionally, the distribution of the cutting margin has been performed by an essentially manual operation by moving each gear stepwise. The rotating wheel was moved radially into the gear and into the groove, and the gear was adjusted in angle until initial contact between the wheel and the surfaces of both teeth was made simultaneously. The initial contact was recognized either by the worker seeing a spark or by hearing the contact sound. Once an even distribution of the shavings was achieved, the gear was rigidly connected to the indexing mechanism and indexed after polishing each tooth groove.

The automatic distribution of the cutting margin according to the invention is achieved by inserting the ball tip B of one sensitive probe between the facing tooth surfaces Fa and Fb. The initial position of the ball chip B is not important. However, in FIG. 2, assuming that both tooth surfaces Fa and Fb are at the same distance,
That is, it is shown as being centered on the center line C of the tooth groove.

The probe tip B may be in the plane of the grindstone or may be separated from the axis of the gear G by a known amount of angle. If the gear is a helical gear, Chip B
Is placed in a twisted position relative to the grindstone. Therefore,
When the position of the gear is adjusted so that the ball chip B is located equidistant from both tooth flanks Ta and Tb, an appropriate distribution of the cutting margin as shown in FIG. 1 is achieved.

According to the invention, the gear is rotated until the probe is activated by one gear, for example the tooth flank Fa. The probe is activated by approaching the tooth surface or by contacting the tooth surface. Such a probe can be easily obtained, and one of such probes is a contact trigger (TT). Upon activation of the probe, the instantaneous angular position Oa of the gear when the tip of the probe is activated is emitted as a signal. This angular position is transmitted to the computer and recorded. In this case, the computer is a numerical control computer (CNC). The computer includes a motor means for rotating the gear to a predetermined position that is precisely determined, and a motor for relatively laterally moving the gear and the grindstone in the axial direction of the gear to a predetermined position that is accurately determined. Connected to both means.

The activation of the probe not only records the instantaneous angular position Oa of the gear, but also reverses the direction of rotation of the gear by computer control. This reversal continues until the probe is activated by the other tooth flank Fb. This determines the second position Ob degree of the gear. This second position Ob degree is transmitted to the computer. This computer is Oa
It is programmed to determine the angular displacement represented by the difference between degrees and Ob degrees. In the simplest case, the computer determines one half of this difference, reverses the way the gears rotate again, and causes the gears to move an angular distance of half the arc Ob-Oa degrees and stop. Control the drive of the motor for this gear. The angular position of the gear at this time is Becomes This is Oc degree. This angular position is a position for true cutting margin distribution in one tooth groove, based on the angular positions Oa and Ob determined by only the probe.

Then, the grinding wheel is inserted into the groove between the tooth surfaces Fa and Fb and fed to an appropriate depth. Relative movement is then performed by computer controlling the lateral motor drive means and, if the gear is a helical gear, by computer controlling the rotation of the gear by the rotary drive means.

The grinding of the tooth flanks Fa and Fb is achieved by one or several successive passes or lateral strokes. The radial feed between successive lateral strokes, as well as the final depth of feed, is preferably achieved by a feed motor controlled by a computer.

FIG. 3 shows diagrammatically the main components of a grinder with a distributor for the cutting margin.

The base 10 has a horizontally movable slide or table 12 therein. A headstock 14 is mounted on the sliding body 12. Mount the motor 16 in the headstock 14. The motor 16 has a drive shaft 18 connected to the shaft of a gear 20 (here a helical gear is shown) as a workpiece. Shaft
The sensor 18 has a sensor 22 that detects the angular positions of the shaft 18 and the gear 20.

The sliding body 12 is driven by the motor 24 via the lateral drive device 26.
Moved laterally. The lateral drive device 26 has means (not shown) for sensing the instantaneous position of the table 12 in the axial direction of the gear 20. The CNC system thus senses the instantaneous angle as well as the axial position of the gear 20. The system is also programmed to relate both positions, thus advancing the gear teeth and the groove in a helical fashion. Naturally, for the flat gear, the motor
The 16 holds the gear so that it does not rotate when the table 12 moves laterally.

The grinding wheel 30 is adjustable in vertical position at the head 32, and the grinding wheel 30 moves around the radial vertical axis of the gear in order to align its plane with the gear groove to be ground. It is adjustable. The grinding wheel 30 is driven by a motor 34 at a predetermined grinding speed.

Head 32 carries a vertically adjustable probe 36. The probe 36 has a probe chip 38. The probe chip 38 may be spherical and has a tip. The tip is actuated by actual contact with the tooth surface or by proximity to the tooth surface. Broadly interpreted, both types of tips are activated by their proximity to the tooth surface. In simple cases, probe tip 38
Need only be in a plane that includes the vertical axis for adjusting the grindstone 30 and the axis of the gear 20. However, this is not necessary and the probe chip 38 may be angularly displaced from this plane by a known amount. This displacement is incorporated into the program of the CNC system. When the probe chip 38 is centered between the tooth flanks, the grindstone 30
Are likewise centered when fed into the working position.

Arranging the gears to rotate exactly as described above with the distribution of the shavings, and then feed the head 32 into position so that the grindstone is inserted into the shavings distribution position in the groove. Thus, the grinding work is carried out. Then table 12
However, it is laterally moved by one or several strokes.
At this time, the head 32 is gradually fed to the full depth between strokes. Next, the head is moved in the radial direction of the gear, and the grindstone is separated from the groove. The gears are indexed in the circumferential direction and the grinding operation is repeated until all teeth have been cycled.

The CNC control system for operating the motor 16 used for the distribution of the cutting margin, the lead control, and the index can be commercially available. Touch trigger (T
T) Chip is the same.

FIG. 4 schematically shows the hardware of the gear positioning device and the cutting margin distributor. This hardware has a TT probe whose output is processed by a signal processor and then read by a numerical control computer (CNC). This computer controls the angular position of the gear via the headstock servo control device for the purpose of distributing and grinding the cutting allowance, and controls the table via the table servo control device for the purpose of gear positioning and other purposes. To do.

FIG. 5 shows a software flow chart. When initiating the work of positioning the gears and distributing the shavings, the probe 36 is moved to a specific position for initiating the work. The starting position is automatically determined by the computer based on the gear size data already incorporated into the computer. The computer then sits on the table 12 until the TT probe senses the gear surface.
To move. Record this position in the computer.

The probe is then inserted into the groove between two adjacent teeth in the gear. Then, the gear is rotated clockwise and counterclockwise to move the left and right flanks (Fa) and (Fa) of the tooth groove.
b) is sensed. Angle O _A degree and O _B of the recording, calculating the average value. If the distribution of the shavings is based on only one tooth groove, the "complete" block is satisfied with a "yes" answer. The machine will then automatically move to the grinding position and stop for the grinding cycle to be started. If the cutting edge is distributed on the basis of more than one tooth groove, the gear is moved to the next detection position and the work loop is repeated again, as shown in FIG.

The rotation for the indexing of the gears for the subsequent grinding of the tooth groove is effected in this grinder by means of a rotary drive motor controlled by a computer.
Therefore, as a result, once the centerline of one tooth groove is determined, indexing is completed for all tooth grooves due to the positioning to accurately index and distribute the cutting margin.

However, there may be differences between the angular widths of several tooth grooves. Therefore, the computer may be programmed to determine the angular width of any number of tooth grooves and obtain the distribution of the cutting margin based on their average value.
This programs the computer to withdraw the probe from the tooth groove following each task, rotates the gear to one or more additional and selected positions, reinserts the probe, and This can easily be achieved by determining the value of the additional angular width of this additional tooth groove. The average of these values is used to control the amount of reverse rotation from the position occupied by the gear after completion of the final width measurement operation.

In addition, even a slight change in the distance from tooth to tooth may cause an error. This is the value of the continuous angular position occupied by the gears during the first and / or the second (and preferably the second) activation of the probe in the continuous tooth groove,
By determining the value of the angular position during the first and / or second activation of the probe in the first tooth groove, respectively, by programming the computer, it is determined during the work of distributing the shavings, and Taken into account. If the tooth-to-tooth spacing is accurate, these continuous values are equal to the angular increments equal to the product of the position of the first gear times the number of grooves from the first tested groove. Will be equal to Correction of the average deviation from the position of the gear determined in the first operation to the amount of reciprocal number from the position occupied in the second probe activation of the tooth gear of the first gear checked. To use as.

As is clear from the above, the simplest task is to probe a single tooth groove to determine the exact position of the gear wheel's groove on the gear grinding wheel. It is to be. Then center the center line of this groove with the grindstone and continue the groove.
Accurately index and grind from the position where the cutting margin is initially distributed.

According to a first variant of the method according to the invention, a reverse angular movement of the gear from the position occupied by the gear at the end of the last probing operation to the position where the cutting margin was first distributed. To determine, the effective average width of several or all of the teeth can be determined and used.

According to a second variant of the method of the invention, by calculating the average position of the indexed teeth from the initial position and the reversal of the gear from the initially probed position, the actual position is Rather, it does so on the basis of this calculated average position to determine the corrected theoretical position of the gear, from which the corrected 1/2 effective groove width can be utilized.

In the simple case described above, the axis of the gear is horizontal and the axis about which the grindstone can be adjusted is vertical and intersects the axis of the gear. The center of the probe chip B, which lies in the vertical plane, contains both the axis of the gear and the axis of the grindstone.
If the gear is a spur gear, the distribution of the cutting allowance by the above-mentioned mechanism will provide an appropriate distribution of the cutting allowance between the grinding wheel and the gear when the gear moves laterally to pass under the grinding wheel. Effective to assure. If the gear is a helical gear, set the grindstone to the proper helix angle. The distance between the vertical axis for adjusting the grindstone and the ball chip B is known and stored in the computer. The ball chip B is centered in a tooth-splitting relationship in the tooth groove at the top of the gear. Observe the rotational position of the gear and then take out the ball chip B by lifting it or by moving the gear laterally toward the grindstone. The correction of the rotation angle of the gear, which is required by the twist angle of the gear and the distance between the center of the top and the vertical axis for adjusting the grindstone, is calculated in the CNC controller and does not involve horizontal lateral movement. This is done by the rotation of gears. The gear is then moved laterally below the wheel with proper rotation, progressive feed of the wheel's grinding depth, and automatic indexing as is known in the art.

EFFECTS OF THE INVENTION As described above, according to the present invention, when a gear is ground by a grindstone whose peripheral cross-sectional shape is shaped into a groove, it is possible to accurately distribute the cutting margin in the groove. It will be possible.

[Brief description of drawings]

FIG. 1 is a schematic view showing distribution of a cutting margin according to the present invention, FIG. 2 is a schematic view showing a probe chip at a distribution position of a cutting margin, FIG. 3 is a simplified elevation view of a grinding machine, and FIG.
The figure is a diagram showing the outline of the hardware of the cutting margin distribution device,
FIG. 5 is a flow chart showing the software of the cutting margin distributing device. 16 …… Motor (spindle drive motor), 18 …… Shaft, 20 …… Gear, 24 …… Motor (horizontal movement drive motor), W, 30 …… Grinding wheel, 36 …… Probe, B, 38 …… Probe chip.

Continuation of the front page (56) References JP 59-161226 (JP, A) JP 60-249525 (JP, A) Japanese Patent Application No. 53-115125 (Japanese Utility Model No. 55-31571) A microfilm (JP, U) of the attached specification and drawings

Claims (5)

[Claims] 1. A rotary spindle for supporting a gear to be processed, a spindle drive motor for rotating the spindle, and a grinding wheel having a peripheral edge portion corresponding to the cross section of the tooth groove of the gear. , A lateral movement drive motor for relatively laterally moving a gear and a grindstone in a direction parallel to the axis of the gear, and a cutting margin distribution provided with one sensitive probe arbitrarily arranged in the groove of the gear. Structure and introduction of the tip tip of the probe into the groove of the gear to be machined fixed to the spindle and keeping the tip away from the groove so that the spindle can be rotated for grinding all teeth A probe positioning device and a computer for slowly starting rotation of the spindle drive motor in one direction when the tip is introduced into a tooth groove. Formula control means and, when the tip approaches one side surface of the tooth groove, sends data of the first angular position of the gear at that time to the computer to store the data, and the control means drives the spindle. And a detection means for performing a first reverse rotation operation by reversing the motor, the detection means for detecting the second angular position of the gear at that time when the tip is close to the other side surface of the tooth groove. The data is sent to the computer to be stored therein, and the controller is configured to reversely rotate the spindle drive motor again to perform a second reverse rotation operation. The computer is configured to detect the first and second angular positions. A second half of the angular difference is determined, and a second reverse rotation by the spindle drive motor is reached when the position of half the angular difference is reached. A tooth profile grinding apparatus having means for ending the operation by the control means. 2. A rotary spindle for supporting a gear to be processed, a spindle drive motor for rotating the spindle, and a grinding wheel having a peripheral edge portion corresponding to the cross section of the groove of the gear. , A lateral movement drive motor for relatively laterally moving a gear and a grindstone in a direction parallel to the axis of the gear, and a cutting margin distribution provided with one sensitive probe arbitrarily arranged in the groove of the gear. A structure, and the tip of the probe is introduced into a plurality of tooth grooves of a gear to be processed fixed to the spindle,
A probe positioning device that moves the tip away from the groove so as to rotate the spindle for grinding all teeth; and slowly rotate the spindle drive motor in one direction when the tip is introduced into the groove. Computer-operated control means for starting; and, when the tip approaches one side surface of a tooth groove, sends the first angular position data regarding the gear at that time to the computer for storage and Means for reversing the spindle drive motor to perform a first reversing operation, and when the tip comes close to the other side surface of the tooth groove, the second angular position data relating to the gear at that time is obtained. Send it to a computer for storage and position the probe so that this probe is moved away from the tooth groove. A probe positioning means for activating the device; and a means for activating the spindle drive motor to rotate the spindle so that the probe is positioned in the next adjacent tooth groove. The device is operated so as to introduce the tip of the probe into the next tooth groove of the gear to be processed, and the control means controls the computer when the tip is introduced into the next tooth groove. The spindle drive motor is actuated to slowly start rotation in one direction, and the detection means is configured to detect the next tooth at that time regarding the gear when the tip is close to the other side surface of the next tooth groove. The data of the first angular position of the groove is sent to the computer for storage and the control means reverses the spindle drive motor. And a second reversing action of the next next tooth groove with respect to the gear when the tip approaches the other side surface of the next next tooth groove. The angular position data is sent to and stored in the computer, and similarly, the first angular position data and the second angular position data for each of the plurality of tooth spaces are sent to and stored in the computer. The computer determines a value of one half of the angular difference between the first and second angular positions for each of the plurality of tooth spaces and is determined by the probe of each of these tooth spaces. A means for averaging the angular differences, wherein the spindle is moved to the last groove in the plurality of tooth grooves to determine the average angular difference, A second step to reversely rotate the spindle drive motor again to perform a second reverse operation, and when the position of the average angle difference is reached, the second reverse operation by the spindle drive motor is ended by the control means. A tooth profile grinding device having means. 3. The computer has means for rotating the spindle drive motor by the control means to cause the spindle to perform an indexing operation at a constant angle equal to the distance between the teeth of the gear. The tooth profile grinding device according to claim 1. 4. A computer-controlled type, wherein a spindle for rotatably supporting a gear to be processed is connected to a spindle drive motor, and the motor is configured to be operated by a control means controlled by a computer. A computer controlled shaving dispenser for a grinding machine, wherein one sensitive probe activated by proximity of one of the teeth of the gear on the spindle to the tooth flank, and a tip of the probe Means for positioning at any position within the tooth groove of the control means, and control means operated by the computer to start rotating the spindle drive motor in one direction when the tip is introduced into the tooth groove. When the tip is close to one side of the tooth groove, the first angular position of the gear at that time is transmitted to the computer. And storing means for rotating the spindle drive motor in the reverse direction by the control means, and the detecting means, when the tip comes close to the other side surface of the tooth groove, The second angular position is transmitted to and stored in a computer, and the control unit is configured to rotate the spindle drive motor in the opposite direction again, and the computer is configured to rotate the angles of the first and second angular positions. It has means for determining the value of one half of the difference and for terminating the second reverse rotation operation by the spindle drive motor by the control means when the position of one half of the angular difference is reached. A cutting margin distributing device for a tooth profile grinding device, which is characterized in that: 5. A method for distributing cutting margins in a grinding machine for grinding gear teeth, using one sensitive probe activated by proximity to one side of a gear tooth groove. , Positioning the tip of the probe at any position in the gear groove, rotating the gear in one direction when the tip is introduced into the groove, and the tip being one side of the groove. When the tip approaches the other side surface of the tooth groove, the first angular position of the gear at that time is detected, and the gear is rotated in the opposite direction. The second angular position is detected, and the gear is rotated in the reverse direction again to obtain a value of one half of the difference between the first and second angular positions, and the reverse rotation again causes 2 of the difference in angular position
A cutting margin distributing method for a tooth profile grinding machine, characterized in that the reverse rotation is terminated again when the position reaches one-half.