JP4517091B2 - Gear finishing by synchronous drive - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a gear finishing method that performs grinding while synchronously rotating a gear to be ground and a finishing forming tool by driving.
[0002]
[Prior art]
When finishing gears such as shaving and honing (including dressing), use a finishing tool such as a rotating whetstone or cutter with internal or external gears and mesh with the gear to be ground. Grinding is performed using sliding contact between the tooth surfaces.
[0003]
In a normal case, the forming tool is driven and the gear to be ground is machined in a so-called accompanying state that rotates with the forming tool under meshing with the forming tool. However, the grinding in the accompanying state does not have a mechanism for forcibly correcting the eccentricity of the gear to be ground and the accumulated pitch error, and as a result, high-precision machining is difficult.
[0004]
On the other hand, high precision can be obtained by processing while driving both the forming tool and the gear to be ground. However, for this, it is indispensable that the forming tool and the gear to be ground are synchronously rotated with high accuracy because it is necessary to mesh the teeth with zero backlash.
[0005]
Various proposals have been made to achieve high-accuracy synchronous rotation, but the tool and the gear to be ground are engaged in a stopped state, and forward and reverse rotation is repeated little by little to move in the cutting direction. In general, after obtaining the zero backlash state, both are driven and rotated synchronously. For example, in the machining method according to Japanese Patent No. 3000668, the gear to be ground is rotated forward and backward by small amounts, the amount of rotational displacement at which the forming tool begins to rotate in each rotational direction is detected, and the backlash is reduced to zero. The position correction amount of the forming tool necessary for this is obtained, and the feed tool is fed to the forming tool based on the position correction amount to achieve synchronization.
[0006]
However, these methods have a drawback in that it is necessary to repeat the minute rotation of the gear to be ground in order to detect the relative position of the forming tool with the sensor, which requires labor and time. Further, in the conventional method, it is necessary to stop the forming tool every time the grinding of the gear to be ground is finished, and to start driving the shaping tool again after the new gear to be ground is mounted. Therefore, the driving and stopping of the heavy forming tool are repeated, and there is a problem that the time efficiency of processing is poor and time-consuming.
[0007]
[Problems to be solved by the invention]
The present invention eliminates the need to stop the forming tool every time the gear to be ground is ground when performing gear finishing by synchronous rotation, and repeats the minute rotation of the forming tool which is troublesome even when stopped. An object of the present invention is to provide a gear finishing method capable of starting continuous rotation of a gear to be ground and a forming tool without need.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a gear finishing method for driving a work support shaft supported by a machine base and a finishing forming tool to rotate synchronously when forming and finishing a gear as a work. The workpiece support shaft and the forming tool are driven by a control motor by servo control by a servo motor or Cs control by an AC spindle motor.
Moving the control motor to the rotation direction origin and attaching the workpiece to the workpiece support shaft; engaging the workpiece positioning device with the workpiece to position the workpiece in the rotation direction; and moving the workpiece to the workpiece positioning device. Clamping with the workpiece support shaft and the core push stand in meshed state, a step of setting the control motor coupled to the workpiece support shaft to a free-run state, and the workpiece support generated in accordance with the free-run state A step of reading the phase shift of the shaft relative to the workpiece support side of the control motor, a step of removing the workpiece positioning device from the workpiece, and adjusting the workpiece support shaft to be rotated by the control motor so as to eliminate the phase shift. The workpiece support shaft and the forming tool are used to control each control motor. In a state where the torque is synchronized and rotated in phase with each other, and the driving torque of the workpiece support shaft is reduced to a level not subject to cutting by the forming tool, or a position set in advance as zero backlash is detected. A step of bringing the workpiece support shaft and the forming tool close to a position; a step of fixing a drive phase of each control motor of the workpiece support shaft and the forming tool at a position of zero backlash; And a step of performing finish cutting by gradually increasing a cutting amount while synchronously rotating the workpiece support shaft and the forming tool by driving.
[0009]
[Action]
In the present invention, when grinding a gear as a workpiece, the workpiece support shaft and the forming tool are driven by servo control by a servo motor or Cs control by an AC spindle motor (c-axis control, that is, rotation angle control around the z-axis). First, the control motor is moved to the rotation direction origin and the work is attached to the work support shaft (primary phase determination).
[0010]
Then, the workpiece positioning device is engaged with the workpiece on the workpiece support shaft to perform positioning in the rotational direction, and the workpiece is clamped by the workpiece support shaft and the core push stand. The workpiece positioning device meshes with the workpiece so as to position the phase of the workpiece corresponding to the rotation direction origin of the main shaft (control motor rotation shaft). Even if the control motor is set at the origin, the phase of the workpiece actually deviates due to an attachment error or the like. Therefore, in this state, the workpiece support shaft is slightly twisted between the workpiece side restrained by the workpiece positioning device and the control motor side restrained by the control motor. When the control motor is in a free-running state in this state, the control motor side of the work support shaft rotates slightly by the amount of twist. If the phase shift caused by this rotation is read and the reference position is adjusted so as to eliminate the phase shift, the workpiece support shaft and the forming tool can be synchronized by the control of each control motor and rotated in phase (2). Next phase determination).
[0011]
Therefore, in this state, the workpiece can be meshed with the forming tool while rotating with a driving force necessary for grinding, but the following operation is further performed in order to obtain more accurate phase alignment. That is, in a state where the driving torque of the workpiece support shaft is reduced to such an extent that it does not receive cutting by the forming tool, the workpiece support shaft and the forming tool are brought close to a position set in advance as a zero backlash or a detected position, In this state, the drive phases of the control motors of the workpiece support shaft and the forming tool are fixed. Thereby, the phase error which inevitably occurs between the positioning device and the forming tool can also be eliminated, and the phase of the workpiece and the forming tool can be accurately matched (tertiary phase determination).
[0012]
In this state, if cutting is performed while gradually increasing the depth of cut, it is possible to perform finish cutting with extremely high accuracy by synchronous drive.
[0013]
The phase of the forming tool is detected by an encoder that reads the position of the teeth or grooves of the forming tool. Therefore, when the forming tool is newly attached to the head, the forming tool is stopped, engaged with the workpiece on the workpiece support shaft in the manual mode, and the engagement of the forming tool is made uniform throughout the entire circumference of the workpiece. Set the phase origin.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. 1, 2, and 3 are a front view, a side view, and a plan view, respectively, of a gear finishing device according to an embodiment of the present invention.
[0015]
The illustrated gear finishing device is configured to hold a gear W (workpiece) W to be ground on a table 10 supported by a machine base B by a holding device. The holding device includes two headstocks 30 and tailstocks 40 that are slidable on the table so as to approach and separate from each other and each have a work support shaft. A grindstone holding device 50 is further mounted on the machine base B.
[0016]
FIG. 4 is a front view mainly showing an operation part of the gear finishing apparatus. As shown in the figure, one (left in the figure) head stock 30 includes a tailstock body 31 supported by the table 10, a work support shaft 32 rotatably supported by the tailstock body, and a tailstock. A drive motor 33 that is coupled to the base body 31 and rotates the work support shaft 32 is provided. The other (right in the figure) tailstock 40 includes a tailstock body 41 supported by the table 10 and a work support shaft 42 rotatably supported by the tailstock body.
[0017]
As shown in FIG. 5, the work support shaft 42 includes a clamp shaft 43 that slides back and forth in the axial direction by a driving device (not shown) attached to the tailstock body 41. Therefore, the workpiece W can be clamped in the rotational direction on the workpiece support shaft by supporting the workpiece W by the workpiece support shafts 32 and 42 with the clamp shaft 43 retracted and then moving the clamp shaft 43 forward. . In this example, the work drive motor 33 is a servo motor so as to enable the control described below.
[0018]
As shown in the drawing, the grindstone holding device 50 is located between the head stock 30 and the tailstock 40 and has a ring-shaped head 52 that supports the rotating grindstone 51, and the head 52 is attached to the work support shafts 32 and 42. And a holding portion 53 that is rotatably supported around a vertical horizontal axis. As shown in FIGS. 2 and 3, the holding unit 53 includes a head drive motor 531 for rotating the head 52 around the work support shaft, and a horizontal axis line perpendicular to the work support shafts 32 and 42. A head tilt motor 532 is provided for rotation. Intermediate gears 534 and 535 mesh with a gear 533 fixed to the output shaft of the head drive motor 531, and these intermediate gears mesh with teeth provided on the outer periphery of the head 52 to drive the head 52. In this way, by driving the outer peripheral gear of the head 52 via the two intermediate gears meshed with the drive gear, low backlash is realized with a simple structure, and high-precision and high-speed synchronous meshing is ensured. . The head drive motor 531 is an AC spindle motor in this example so as to enable the control described below. A cutting drive unit 60 on the machine base is coupled to the grindstone holding device 50. The notch driving unit 60 can move along a horizontal axis perpendicular to the workpiece support shafts 32 and 42 by driving of a horizontal drive motor 61, and the head 52 and the rotating grindstone 51 approach the workpiece on the workpiece support shaft by the movement. Separate them and make a cut when grinding.
[0019]
The movement and rotation of the head stock 30, tailstock 40, work drive motor 33, head drive motor 531, etc. are controlled by a control device 70 having an operation panel 71.
[0020]
A work positioning device 80 is attached to the head stock 30. The workpiece positioning device performs accurate positioning in the rotation direction of the workpiece in order to obtain accurate meshing with the forming tool. For example, the workpiece positioning device can be configured as follows. As shown in FIG. 6, the workpiece positioning device 80 includes a fixing portion 81 fastened with a bolt to a workpiece mounting side end portion of the head stock 30, and an arm mounting base is slidable on a slide guide 82 on the fixing portion. 83 is installed. The arm 84 is fixed at the base end to the arm mounting base 83, and a conical protrusion 85 having a size capable of entering between the teeth of the workpiece W is attached to the distal end. Further, a driving cylinder 86 is attached to the fixed portion 81, and a piston rod 87 that cooperates with the driving cylinder 86 is coupled to the arm base end portion. Therefore, the arm 84 is driven by the drive cylinder 86, guided by the slide guide 82, and slides in the radial direction of the work support shaft 32. A dock plate 88 is fixed to the fixed portion 81, and a proximity switch 89 for detecting the forward / backward end of the arm is attached to the dock plate. As a result, the arm 84 moves back and forth between a forward position where the arm 84 meshes with the workpiece W and a reverse position where the mesh is released. The protrusion 85 at the tip of the arm during advancement meshes with the teeth of the workpiece W and positions the workpiece in the rotational direction, as shown in the detailed view of part a in FIG.
[0021]
As the workpiece driving motor 33 and the head driving motor 521, a control motor capable of synchronizing the rotation direction and controlling the phase accurately as described above is used, and specifically, a servo motor or an AC spindle motor.
[0022]
Next, a more detailed configuration of the gear finishing device will be described together with the operation procedure of the device.
[0023]
The phase of the rotating grindstone 51 is detected by an encoder that reads the position of the teeth or grooves of the rotating grindstone. When the rotating grindstone 51 is newly attached to the head 52, the rotating grindstone is stopped and meshed with the workpiece on the workpiece support shaft in the manual mode, and the meshing of the rotating grindstone is made uniform throughout the entire circumference of the workpiece. Set the phase origin.
[0024]
After this preparation is completed, the work drive motor 33 of the headstock 30 is returned to the origin in the encoder, thereby bringing the work drive motor 33 into a servo lock state. Before or after this operation, the workpiece W is mounted on the workpiece support shaft. (Step 1)
Thereafter, the head driving motor 532 is operated to drive the head 52. The rotational speed of the head 52 is adapted to the cutting speed of the workpiece W. Thereafter, the head continues to rotate until a stop command is issued. In this state, the tailstock 40 is brought close to the headstock 30 and the work W is held by the work support shafts 32 and 42. Here, the clamp shaft 43 of the workpiece support shaft 42 is in the retracted position. (Step 2)
Next, the arm 82 of the workpiece positioning device 80 is moved, and the protrusion 83 is inserted between the teeth of the workpiece W, thereby positioning the workpiece W in the rotation direction. For the workpiece W on the workpiece support shaft 32, the phase of the workpiece W itself and the phase of the drive motor do not necessarily match due to variations in machining accuracy of the workpiece W, distortion due to heat treatment, attachment errors to the jig, and the like. Therefore, the workpiece positioning device 80 accurately determines the phase of the workpiece W itself. (FIG. 7A) (Step 3)
The clamp shaft 43 of the workpiece support shaft 42 is advanced while maintaining the meshing state with the projection 83, and the workpiece W is fixed on the workpiece support shafts 32 and 42 in the rotation direction. (Step 4)
The drive motor 33 is servo-off while maintaining the meshing state between the workpiece W and the workpiece positioning device 80. As a result, the work support shaft 32 is in a free-run state without any restriction in the rotation direction. As described above, even if the work drive motor 33 is in the origin return state, the phase of the work W on the work support shaft 32 in the rotational direction does not necessarily match the phase of the drive motor due to various factors. Therefore, the phase of the workpiece W is accurately determined by meshing with the workpiece positioning device 80. Therefore, normally, a slight shift in the rotational direction occurs between the workpiece W positioned by the workpiece positioning device 80 and the workpiece drive motor 33 in the return to origin position. This shift causes elastic torsional deformation between the support portion of the work support shaft 32 by the work drive motor 33 and the support portion of the work W. Therefore, the work support motor 32 is returned to the torsional deformation at the place supported by the work drive motor 33 by setting the work drive motor 33 in the free run state while maintaining the meshed state of the work W and the work positioning device 80. Rotate slightly. (Step 5)
A slight correction rotation amount of the work support shaft 32 generated by setting the work drive motor 33 to the free-run state is read from the encoder. In this case, it is desirable to set so as to prompt the return to the initial setting by generating an abnormal signal or the like if the corrected rotation amount is excessive. The read correction rotation amount is newly stored as the origin position by the programmable controller or the macro program. (FIG. 7B) (Step 6)
From this state, the workpiece positioning device 80 is retracted away from the workpiece W. (FIG. 7C) (Step 7)
After the workpiece positioning device 80 moves backward, the workpiece driving motor 33 is operated to rotate the workpiece support shafts 32 and 42. In parallel with this, the table 10 is moved to bring the workpiece W closer to the center of the rotating grindstone 51. (FIG. 7D) (Step 8)
While the workpiece W approaches the center of the rotating grindstone 51, the workpiece support shaft 32 is synchronized and phased. That is, it is detected by the encoder coupled to the work support shaft 32 and the head 52 that the work support shaft 32 has reached the synchronous speed with respect to the rotary grindstone 51, and then based on the origin corrected in the above-mentioned step 5. Perform phase alignment. In parallel with this, the cutting drive unit 60 is actuated to advance the rotating grindstone 51 toward the workpiece W side (z-axis direction). (FIG. 7E) (Step 9)
After completion of the synchronization phase alignment, the rotary grindstone 51 is further advanced to a position where the both ends of the rotating grindstone 51 and the workpiece W are slightly engaged. At this time, it is desirable to use cutting feed instead of rapid feed in order to prevent tooth damage due to collision. (FIG. 7F) (Step 10)
After reaching the position where the tips of both teeth of the rotating grindstone 51 and the workpiece W are sufficiently engaged with each other, the output torque of the workpiece driving motor 33 is lowered to an extent where cutting is impossible. (Step 11)
Further, the rotary grindstone 51 continues to advance until the backlash between the rotary grindstone 51 and the workpiece W becomes zero by the cutting drive unit 60. The detection of zero backlash can be performed based on the torque control function. The backlash state is not uniform in the direction in which the teeth are arranged due to the processing accuracy of the rotating grindstone 51 and the workpiece W, distortion due to heat treatment, attachment error to the jig, and the like. On the other hand, for example, the following means can be applied. The feed torque in the z-axis direction by the horizontal drive motor 61 is kept constant, and the previous and current z-axis coordinate values are changed every scan (one round of processing from the beginning to the end of the feed control program in the programmable controller) by the programmable controller. Compare. When the difference becomes a small value that can be regarded as zero or substantially zero, the backlash is zero. Alternatively, the position of the rotating grindstone in the z-axis direction in which the workpiece and the rotating grindstone are meshed in advance in the manual mode and zero backlash is detected, and the rotating grindstone 51 is advanced to the position set by the detection data. Also good. (FIG. 7G) (Step 12)
When the backlash is zero, the rotary grindstone 51 stops immediately. At this time, since the workpiece support shaft 32 limits the torque, the workpiece W is being rotated with respect to the rotating grindstone 51. Therefore, there is a deviation from the electrical synchronization and phase matching position set in step 6. The position where the backlash between the rotating grindstone 51 and the workpiece W becomes zero is formally recognized by the programmable controller or the like as the synchronization and phase matching position of the master (rotating grindstone) and slave (workpiece axis). (Step 13)
In the following, grinding will be started, but this method has a plurality of selectable forms as described below.
[0025]
At the same time as the rotary grindstone 51 is advanced by plunge feed (the head is advanced while the table is fixed), the restriction on the output torque of the work drive motor 33 is gradually released. At this time, the torque of the work drive motor 33 and the feed speed of the rotating grindstone 51 are controlled so that no electrical phase shift occurs. (Step 14)
Instead of the step 15, the output torque limit of the work drive motor 33 is canceled and the constant torque cutting can be performed to the maximum value set. (Step 14A)
Thereafter, the table 10 is reciprocated in the workpiece support axis direction (left and right direction in FIG. 4) to perform grinding. For this purpose, every time the table switches the moving direction, cutting is performed (Z-axis). When the workpiece W is a helical gear, grinding is performed while performing helical correction. (Step 15)
When step 15A is used, instead of step 16, the current of the work drive motor 33 is detected and the feed speed of the rotating grindstone 51 by the horizontal drive motor 61 is automatically adjusted so that grinding can be performed with a constant torque. Parallel feed is performed. (Step 15A)
During parallel feeding, the crowning shaft (B-axis) is driven to perform crowning. Parallel feed is performed while the table (X axis) gradually increases the moving distance from the center. Further, every time the table (X-axis) switches the direction, the horizontal drive motor 61 moves forward (Z-axis). And it processes until it reaches the setting position of the cutting axis (z-axis) corresponding to the final shape of the workpiece. (Step 16)
When reaching the set position, in order to grind the flank on the opposite side of the tooth of the workpiece W, the synchronization phase is shifted in the opposite direction to the previous direction. The amount of phase shift is determined by the program. (Step 17)
When finishing the flank on both sides, it is desirable to perform final finishing. This can be done by restricting the torque of the work drive motor 33 again, turning the work support shaft around, performing table feed and crowning without cutting. (Step 18)
Next, the rotary grindstone 51 is moved backward from the work W, and then the work drive motor 33 is stopped by releasing the synchronization. Further, the table 10, the rotating grindstone 51, each of the crowning axes (X axis, Z axis, B axis) and the work drive motor 33 are returned to the origin. As a result, the machining of one workpiece W is completed, and the next workpiece is ready for machining. (Step 19)
[0026]
【The invention's effect】
In the present invention, the workpiece support shaft and the forming tool are driven by servo control by a servo motor or Cs control by an AC spindle motor, and the phase is determined by the control (primary phase determination). Further, the phase is corrected by the work positioning device, and the reference position is adjusted by reading the phase shift by setting the control motor in a free-run state (secondary phase determination). Further, the drive phase of each control motor of the workpiece support shaft and the forming tool is fixed as a zero backlash state with the drive torque of the workpiece support shaft lowered (tertiary phase determination). In this way, the phase of the workpiece and the forming tool can be matched exactly. In this state, if cutting is performed by gradually increasing the cutting depth, finish cutting with extremely high accuracy by synchronous driving can be performed. The above operation can be performed without stopping the rotation of the forming tool once the forming tool has been phased.
[Brief description of the drawings]
FIG. 1 is a front view of a gear finishing device according to a primary embodiment of the present invention.
FIG. 2 is a side view of the gear finishing apparatus shown in FIG.
FIG. 3 is a plan view of the gear finishing apparatus shown in FIG.
FIG. 4 is a front view mainly showing an operation part of the gear finishing device shown in FIG. 1;
5 is a front view centering on a workpiece support state of the gear finishing device shown in FIG. 1. FIG. 6 is a perspective view showing a use state of the workpiece positioning device in the gear finishing device shown in FIG.
FIG. 7 is an explanatory view showing a processed body by the gear finishing device shown in FIG. 1;
8A is a flowchart showing an operation procedure in a workpiece support state of the gear finishing device shown in FIG. 1. FIG.
FIG. 8B is a flowchart following FIG. 8A.
[Explanation of symbols]
10 table 10, 20 holding device,
30, 40 Tailstock, 31 Tailstock body,
32 workpiece support shaft, 33 workpiece drive motor,
41 Tailstock body, 42 Work support shaft,
50 grinding wheel holding device, 51 rotating grinding wheel,
53 holding part, 531 head drive motor,
60 cutting drive unit, 80 workpiece positioning device,
W Work

Claims (3)

A gear finishing processing method for driving a workpiece supporting shaft supported by a machine base and a finishing forming tool to rotate synchronously when forming and finishing a gear which is a workpiece,
The workpiece support shaft and the forming tool are driven by a control motor by servo control by a servo motor or Cs control by an AC spindle motor.
The gear finishing method is:
Moving the control motor to the rotation direction origin and attaching the workpiece to the workpiece support shaft;
Engaging the workpiece positioning device with the workpiece to position the workpiece in the rotational direction;
Clamping the workpiece with the workpiece support shaft and the core push stand in a state where the workpiece is engaged with the workpiece positioning device;
Bringing the control motor coupled to the workpiece support shaft into a free-running state;
A step of reading a phase shift with respect to the work support side on the control motor side of the work support shaft generated in a free-run state;
Removing the workpiece positioning device from the workpiece;
Rotating the workpiece support shaft by the control motor, adjusting the phase shift to be eliminated, synchronizing the workpiece support shaft and the forming tool by the control of each control motor, and rotating in phase with each other; and
The work support shaft and the forming tool are brought close to a position set in advance or detected as zero backlash in a state where the driving torque of the work support shaft is reduced to a level that is not subject to cutting by the forming tool. Step to
Fixing the drive phase of each control motor of the work support shaft and the forming tool at the position of zero backlash;
And a step of performing finish cutting by gradually increasing a cutting amount while synchronously rotating the workpiece support shaft and the forming tool by driving each control motor. The gear finishing method according to claim 1, wherein the step of performing the finish cutting is performed while gradually increasing the driving torque of the workpiece support shaft to a normal value. 2. The gear finishing according to claim 1, wherein the step of performing the finish cutting is performed while detecting a drive load current value of a servo motor or an AC spindle motor of the forming tool or workpiece support shaft and adjusting a cutting speed. Processing method.

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