JP2022084109A - Gear processing method and gear processing device - Google Patents

Abstract

To provide a gear processing method which prevents burrs from remaining on a tooth surface in processing at a high cutting speed.SOLUTION: A gear processing method comprises: a tooth surface processing process (A1→A3) in which a work-piece W and a cutting tool T are synchronously rotated in the state where a rotation axis Cw of the work-piece W and a rotation axis Ct of the cutting tool T are located in parallel, thereby moving a cutting edge tip Tb3 of the cutting tool T along a prescribed locus with respect to the work-piece W, and one of tooth surfaces Wb in each tooth groove Wa is processed from a tooth tip toward a tooth bottom of the tooth surface Wb; a temporary retraction process (A3→A4) in which the cutting edge tip Tb3 is moved to a temporary retraction position when arriving at a processing end point of the tooth surface Wb; a return process (A4→A5) in which the cutting edge tip Tb3 is returned to the prescribed locus from the temporary retraction position; and a retraction process (A5→A7) in which the cutting edge tip Tb3 is moved along the prescribed locus, and the cutting edge tip Tb3 is retracted from an internal space of the tooth groove Wa to the outside of the tooth groove Wa.SELECTED DRAWING: Figure 7

Description

The present invention relates to a gear processing method and a gear processing apparatus.

In Patent Document 1, the cutting edge trajectory of the cutting tool is made into a cycloid curve by synchronously rotating the workpiece and the cutting tool in a state where the rotation axis of the workpiece and the rotation axis of the cutting tool are arranged in parallel. It is described that the tooth surface of the tooth surface is machined. Patent Document 2 describes that gear processing is performed by a skiving cutter.

German Patent Application Publication No. 10329413 Japanese Unexamined Patent Publication No. 2020-19096

The cutting method described in Patent Document 1 can obtain a higher cutting speed than the skiving process described in Patent Document 2. In the cutting method, the tooth surface of the gear is processed from the tooth tip toward the tooth bottom, and is folded back at the processing end point near the tooth bottom of the tooth surface. Due to this folding, burrs tend to remain near the bottom of the tooth surface. In particular, when trying to process up to the vicinity of the tooth bottom of the tooth surface, burrs are more likely to remain.

An object of the present invention is to provide a gear processing method and a gear processing apparatus that suppresses burrs from remaining on the tooth surface in processing at a high cutting speed.

(1. Gear processing method)
The gear processing method is a gear processing method for processing the tooth surface in the tooth groove of the tooth profile on a gear-shaped workpiece having a tooth profile formed in advance, and is a rotation axis of the workpiece and a rotation axis of a cutting tool. By rotating the workpiece and the cutting tool in synchronization with each other in parallel with each other, the cutting edge of the cutting tool is moved with respect to the workpiece along a predetermined locus, and the tooth surface in each of the tooth grooves. In the tooth surface processing step of processing one of the tooth surfaces from the tooth tip to the tooth bottom, and when the processing end point of the tooth surface is reached, the cutting tool cutting tool is placed in the internal space of the tooth groove. A temporary retracting step of moving the cutting tool from the predetermined locus to a different temporary retracting position at a non-contact position with the tooth surface, and returning the cutting tool edge of the cutting tool from the temporary retracting position to the predetermined locus in the internal space of the tooth groove. A return step and a retracting step of moving the cutting tool edge of the cutting tool along the predetermined trajectory and retracting the cutting tool edge from the internal space of the tooth groove to the outside of the tooth groove after returning to the predetermined trajectory. And prepare.

According to the gear machining method, after the tooth surface machining step, the cutting edge of the cutting tool is moved from a predetermined locus to a different temporary retracted position. By this temporary evacuation operation, it is possible to prevent burrs from remaining near the processing end point of the tooth surface. After that, the cutting edge of the cutting tool returns to a predetermined locus in the return step, and retracts from the internal space of the tooth groove along the predetermined locus. Therefore, in the next machining, the cutting edge of the cutting tool can move along the predetermined locus again to carry out the tooth surface machining step.

In other words, by rotating the workpiece and the cutting tool synchronously with the rotation axis of the workpiece and the rotation axis of the cutting tool arranged in parallel, a high-speed cutting speed can be obtained and burrs can be obtained by the temporary evacuation process. Can be suppressed from remaining.

(2. Gear processing equipment)
The gear processing device is a gear processing device that processes a tooth surface in a tooth groove of the tooth profile on a gear-shaped workpiece having a tooth profile formed in advance, and includes a cutting tool, the workpiece, and the cutting tool. It is equipped with a control device for controlling.

The control device causes the cutting tool to rotate synchronously with the work in a state where the rotation axis of the work and the rotation axis of the cutting tool are arranged in parallel. The cutting edge is moved along a predetermined locus to reach the tooth surface processing portion for processing one of the tooth surfaces in each tooth groove from the tooth tip of the tooth surface toward the tooth bottom and the processing end point of the tooth surface. At that time, the cutting tool cutting tool is moved to a temporary retracting position that is a non-contact position with the tooth surface in the internal space of the tooth groove and is different from the predetermined locus, and the temporary retracting portion and the internal space of the tooth groove. The cutting tool has a return portion that returns the cutting tool edge from the temporary retracted position to the predetermined trajectory, and after returning to the predetermined trajectory, the cutting tool edge is moved along the predetermined trajectory to move the cutting tool edge. Is provided with a retracting portion for retracting the tooth from the internal space of the tooth groove to the outside of the tooth groove. According to the gear processing apparatus, the same effect as that of the gear processing method can be obtained.

It is a figure which shows the machine tool. It is a figure which shows a work piece and a cutting tool. It is a perspective view which shows the cutting tool of 1st example. It is a perspective view which shows the cutting tool of the 2nd example. It is a functional block diagram which shows the control device. It is a figure which shows the relative operation locus of a tool blade of a cutting tool with respect to a work piece. It is a figure which shows the relative operation locus of the cutting edge of the tool blade of a cutting tool with respect to a work piece. It is a graph which shows the control method of 1st example. It is a graph which shows the control method of the 2nd example. It is a graph which shows the control method of the 4th example. It is a graph which shows the control method of the 5th example. It is a flowchart which shows the processing condition determination process.

(1. Work)
The workpiece before cutting is a gear shape having a tooth profile formed on the outer peripheral surface or the inner peripheral surface. That is, the workpiece before cutting has a tooth profile formed in advance. The tooth surface in the tooth groove of the tooth profile is the cutting portion. The tooth surface after cutting is formed into an involute curve. That is, by cutting the preformed tooth surface, the finished shape of the involute curve is formed while reducing the tooth thickness. The tooth surface before cutting may have an involute curve or a shape other than the involute curve.

Further, the tooth profile of the work W may be such that the tooth streak direction is parallel to the rotation axis of the work W, or the tooth streak direction may have an angle with respect to the rotation axis of the work W. The tooth surface Wb of the former workpiece W is the tooth surface of the spur gear, and the tooth surface Wb of the latter workpiece W is the tooth surface of the helical gear.

(2. Example of machine tool 1)
The machine tool 1, which is a gear processing device that cuts the tooth surface of a gear that is a work piece W, is a device that cuts the tooth surface by the cutting tool T by relatively moving the cutting tool T and the work piece W. Is. Further, the target machine tool 1 is composed of a plurality of structures for relatively moving the cutting tool T and the workpiece W. The target machine tool 1 is, for example, a machining center.

An example of the machine tool 1 will be described with reference to FIG. In this example, the machine tool 1 uses a machining center capable of exchanging tools as an example. In particular, in the machining center as the machine tool 1, in addition to cutting the tooth surface in this example, the tooth profile may be cut in advance on the workpiece W by gear skiving, hobbing, or the like. The machining center as the machine tool 1 has a horizontal machining center as a basic configuration. The machine tool 1 has the above configuration as an example, but other configurations such as a vertical machining center can be applied.

As shown in FIG. 1, the machine tool 1 has, for example, three linear axes (X-axis, Y-axis, and Z-axis) orthogonal to each other as drive axes. Here, the direction of the rotation axis of the cutting tool T (equal to the rotation axis of the tool spindle) is defined as the Z-axis direction, and the two axes orthogonal to the Z-axis direction are defined as the X-axis direction and the Y-axis direction. In FIG. 1, the horizontal direction is the X-axis direction and the vertical direction is the Y-axis direction. Further, the machine tool 1 further has two rotation axes (B axis and Cw axis) for changing the relative postures of the cutting tool T and the workpiece W as drive axes. Further, the machine tool 1 has a Ct axis as a rotation axis for rotating the cutting tool T.

That is, the machine tool 1 is a 5-axis machine tool capable of machining a free curved surface (it becomes a 6-axis machine tool when the tool spindle (Ct axis) is taken into consideration). Here, the machine tool 1 has an A axis (X axis in the reference state) instead of a configuration having a B axis (rotation axis around the Y axis in the reference state) and a Cw axis (rotation axis around the Z axis in the reference state). It may be configured to have a rotating axis) and a B axis, or it may be configured to have an A axis and a Cw axis.

In the machine tool 1, a configuration in which the cutting tool T and the workpiece W are relatively moved can be appropriately selected. In this example, the machine tool 1 allows the cutting tool T to move linearly in the Y-axis direction and the Z-axis direction, allows the workpiece W to move linearly in the X-axis direction, and further allows the workpiece W to rotate in the B-axis and Cw-axis. Make it rotatable. Further, the cutting tool T is rotatable on the Ct axis.

The machine tool 1 includes a bed 10, a work holding device 20, and a tool holding device 30. The bed 10 is formed in an arbitrary shape such as a substantially rectangular shape, and is installed on the floor surface. The work holding device 20 makes the work W linearly movable with respect to the bed 10 in the X-axis direction, and enables B-axis rotation and Cw-axis rotation. The work holding device 20 mainly includes an X-axis moving table 21, a B-axis rotary table 22, and a work spindle device 23.

The X-axis moving table 21 is provided so as to be movable in the X-axis direction with respect to the bed 10. Specifically, the bed 10 is provided with a pair of X-axis guide rails extending in the X-axis direction (front-back direction in FIG. 1), and the X-axis moving table 21 is driven by a linear motor or a ball screw mechanism (not shown). As a result, it reciprocates in the X-axis direction while being guided by the pair of X-axis guide rails.

The B-axis rotary table 22 is installed on the upper surface of the X-axis moving table 21 and reciprocates in the X-axis direction integrally with the X-axis moving table 21. Further, the B-axis rotary table 22 is provided so as to be rotatable on the B-axis with respect to the X-axis moving table 21. A rotary motor (not shown) is housed in the B-axis rotary table 22, and the B-axis rotary table 22 can rotate on the B-axis by being driven by the rotary motor.

The work spindle device 23 is installed on the B-axis rotary table 22 and rotates on the B-axis integrally with the B-axis rotary table 22. The geographic head shaft device 23 includes a geographic head shaft base 23a, a geographic head shaft housing 23b, and a geographic head shaft 23c. The work spindle base 23a is fixed to the upper surface of the B-axis rotary table 22.

The geographic head shaft housing 23b is fixed to the geographic head shaft base 23a and has a cylindrical inner peripheral surface centered on the Cw axis center line orthogonal to the B axis center line. The work spindle 23c is rotatably supported by the work spindle housing 23b. The workpiece W is detachably held on the workpiece spindle 23c. That is, the work spindle 23c holds the work W rotatably around the Cw axis in the work spindle housing 23b, and rotates integrally with the work W.

Inside the work spindle housing 23b, a rotary motor (not shown) for rotating the work spindle 23c and a detector (not shown) such as an encoder for detecting the rotation angle of the work spindle 23c are provided. In this way, the work holding device 20 makes the work W movable with respect to the bed 10 in the X-axis direction, and can be rotated around the B axis and around the Cw axis.

The tool holding device 30 mainly includes a column 31, a saddle 32, and a tool spindle device 33. The column 31 is provided so as to be movable in the Z-axis direction with respect to the bed 10. Specifically, the bed 10 is provided with a pair of Z-axis guide rails extending in the Z-axis direction (left-right direction in FIG. 1), and the column 31 is driven by a linear motor or a ball screw mechanism (not shown) to form a pair. It reciprocates in the Z-axis direction while being guided by the Z-axis guide rail.

The saddle 32 is a side surface of the column 31 on the W side of the workpiece (the left side surface of FIG. 1), and is arranged on the side surface parallel to the plane orthogonal to the Z-axis direction. A pair of Y-axis guide rails extending in the Y-axis direction (vertical direction in FIG. 1) are provided on the side surface of the column 31, and the saddle 32 is driven by a linear motor or a ball screw mechanism (not shown) to Y. It moves back and forth in the axial direction.

The tool spindle device 33 is installed in the saddle 32 and moves integrally with the saddle 32 in the Y-axis direction. The tool spindle device 33 includes a tool spindle housing 33a and a tool spindle 33b. The tool spindle housing 33a is fixed to the saddle 32 and has a cylindrical inner peripheral surface centered on the Ct axis center line parallel to the Z axis. The tool spindle 33b is rotatably supported by the tool spindle housing 33a. The cutting tool T is detachably held on the tool spindle 33b. That is, the tool spindle 33b holds the cutting tool T in the tool spindle housing 33a so that the Ct axis can rotate, and rotates integrally with the cutting tool T.

Inside the tool spindle housing 33a, a tool rotation motor (not shown) for rotating the tool spindle 33b and a detector (not shown) such as an encoder for detecting the rotation angle of the tool spindle 33b are provided. In this way, the tool holding device 30 makes the cutting tool T movable with respect to the bed 10 in the Y-axis direction and the Z-axis direction, and holds the cutting tool T so as to be rotatable in the Ct axis.

(3. Detailed configuration of cutting tool T)
(3-1. Detailed configuration of the cutting tool T of the first example)
The configuration of the cutting tool T will be described with reference to FIGS. 2 and 3. The cutting tool T of the first example is a rotary tool that cuts the tooth surface Wb in the tooth groove Wa of the workpiece W whose tooth trace direction is parallel to the rotation axis of the workpiece W. The rotation axis Cw of the workpiece W and the rotation axis Ct of the cutting tool T are arranged in parallel. In this state, the cutting tool T cuts the tooth surface Wb of the gear which is the workpiece W by rotating it synchronously with respect to the workpiece W.

The cutting tool T includes a tool body Ta and a tool blade Tb. The tool body Ta is formed in a columnar shape, for example, and is held by the tool spindle 33b so that the center axis coincides with the Ct axis center line of the tool spindle 33b. The tool body Ta is formed of, for example, a steel material.

The tool blade Tb is provided at the tip of the tool body Ta so as to project outward in the radial direction of the tool body Ta. The tool blade Tb is formed of, for example, cemented carbide. The tool blade Tb is formed in a plate shape. That is, the tool blade Tb is formed in a plate shape extending in the radial direction of the cutting tool T in the cross section perpendicular to the axis of the cutting tool T. In particular, in this example, the tool blade Tb is formed in a trapezoidal shape when viewed from the plate-shaped surface normal direction. However, the shape of the tool blade Tb is not limited to the trapezoidal shape, and may be formed into a rectangular shape.

Since the cutting tool T of the first example is intended for cutting a tooth surface Wb whose tooth streak direction is parallel to the rotation axis of the workpiece W, the tool blade Tb of the cutting tool T has a plate extending direction. It is provided so as to be parallel to the central axis of the tool body Ta.

Therefore, the tool blade Tb includes a tip surface Tb1 outside the radial direction of the cutting tool T and a side surface Tb2 facing the circumferential direction of the cutting tool T. In the tool blade Tb, the portion where the tooth surface Wb of the workpiece W is cut is the ridge line portion Tb3 (blade edge) between the tip surface Tb1 and the side surface Tb2.

Here, in FIG. 2, the workpiece W exemplifies an external gear, but it can also be an internal gear. In this case, the cutting tool T is located inside the workpiece W which is an internal gear, and the rotation axis Ct of the cutting tool T is eccentric with respect to the rotation axis Cw of the workpiece W.

(3-2. Detailed configuration of the cutting tool T of the second example)
The configuration of the cutting tool T of the second example will be described with reference to FIG. The cutting tool T of the second example is a rotary tool that cuts a tooth surface Wb whose tooth streak direction has an angle with respect to the rotation axis of the workpiece W. That is, the cutting tool T of the second example is a tool for cutting the tooth surface of the helical gear.

The tool blade Tb of the cutting tool T is provided along the line of the twist angle of the cutting tool T corresponding to the twist angle of the tooth surface Wb of the workpiece W. The tool blade Tb has a side surface Tb2 having a three-dimensional curved surface along the line of the cutting tool T corresponding to the helix angle of the tooth surface Wb of the workpiece W.

(4. Configuration of control device 50)
The functional block configuration of the control device 50 of the machine tool 1 described above will be described with reference to FIG. The control device 50 includes a processing condition storage unit 51, a tooth surface processing unit 52, a temporary evacuation unit 53, a return unit 54, and an evacuation unit 55.

The machining condition storage unit 51 stores machining conditions when cutting the tooth surface Wb of the workpiece W with the cutting tool T. The machining conditions are the rotation speed of the cutting tool T, the rotation speed of the workpiece W, the relative position of the rotation axis Ct of the cutting tool T with respect to the rotation axis Cw of the workpiece W, and the cutting tool T with respect to the rotation phase of the workpiece W. Relative rotation phase of.

The tooth surface processing unit 52, the temporary evacuation unit 53, the return unit 54, and the evacuation unit 55 control the drive device 60 such as a motor based on the processing conditions stored in the processing condition storage unit 51. As will be described in detail later, the tooth surface processing unit 52 controls to process the tooth surface Wb from the tooth tip toward the tooth bottom while allowing the tool blade Tb to enter the tooth groove Wa along a predetermined locus. ..

The temporary retracting unit 53 controls to move the cutting edge Tb3 of the tool blade Tb to a temporary retracting position which is a non-contact position with the tooth surface Wb in the internal space of the tooth groove Wa when the machining end point of the tooth surface Wb is reached. conduct. The return unit 54 controls to return the cutting edge Tb3 of the tool blade Tb from the temporary retracted position to a predetermined locus. The retracting portion 55 controls to move the cutting edge Tb3 of the tool blade Tb along a predetermined locus and retract it out of the tooth groove Wa.

(5. Cutting method)
A method of cutting the tooth surface Wb of the workpiece W by the cutting tool T will be described with reference to FIGS. 6 and 7. As shown in FIG. 2, the two-dot chain line of FIG. 6 is for cutting when it is assumed that the workpiece W is fixed when the workpiece W rotates clockwise and the cutting tool T rotates counterclockwise. The operation locus of the tool blade Tb of the tool T is shown.

That is, the tool blade Tb moves in the order of A1 → A2 → A3 → A4 → A5 → A6 → A7. Since the cutting tool T rotates counterclockwise (see FIG. 2), the posture of the tool blade Tb changes from A1 to A7 with respect to the base end (upper end of FIG. 6) of the tool blade Tb. The cutting edge Tb3 of Tb moves counterclockwise. Since the cutting tool T rotates in synchronization with the rotation of the workpiece W, the rotation axis of the cutting tool T substantially revolves with respect to the workpiece W. Therefore, the position and orientation of the tool blade Tb change with respect to the workpiece W as shown in FIG.

In FIG. 7, the thick solid line is the relative operation locus of the cutting edge Tb3 of the tool blade Tb of the cutting tool T with respect to the workpiece W. That is, as shown in FIG. 7, the workpiece W and the cutting tool T are rotated synchronously with the rotary axis Cw of the workpiece W and the rotary axis Ct of the cutting tool T arranged in parallel. As shown in A1 → A2 → A3, the cutting edge Tb3 of the tool blade Tb is moved along a predetermined trajectory with respect to the workpiece W. The predetermined trajectory is a cycloid curve. During this operation, the cutting edge Tb3 of the tool blade Tb processes one of the tooth surfaces Wb in the tooth groove Wa from the tooth tip of the tooth surface Wb toward the tooth bottom (tooth surface processing step). This tooth surface processing step is controlled by the tooth surface processing unit 52 in the control device 50 shown in FIG.

At A3, the processing end point of the tooth surface Wb is reached. Subsequently, as shown in A3 → A4, when the machining end point of the tooth surface Wb is reached, the cutting edge Tb3 of the tool blade Tb is placed at a predetermined non-contact position with the tooth surface Wb in the internal space of the tooth groove Wa. Move from the locus (cycloid curve) to a different temporary evacuation position (temporary evacuation step). Specifically, the cutting edge Tb3 of the tool blade Tb is moved to the temporary retracted position by relatively moving the cutting edge Tb3 of the tool blade Tb in the circumferential direction of the workpiece W in the internal space of the tooth groove Wa. This temporary evacuation step is controlled by the temporary evacuation unit 53 in the control device 50 shown in FIG.

Subsequently, as shown in A4 → A5, the cutting edge Tb3 of the tool blade Tb is returned to a predetermined locus (cycloid curve) from the temporary retracted position in the internal space of the tooth groove Wa (returning step). The return position in A5 is a position on a predetermined locus (cycloid curve) different from the position in A3 of the processing end point of the tooth surface Wb. More specifically, the return position in A5 is located in the predetermined locus (cycloid curve) in the direction in which the cutting edge Tb3 of the tool blade Tb is away from the tooth bottom of the tooth groove Wa with respect to the position of the machining end point in A3. Further, the return position in A5 is not in contact with the tooth surface Wb. The return step is controlled by the return unit 54 in the control device 50 shown in FIG.

Subsequently, after the cutting edge Tb3 of the tool blade Tb returns to the predetermined locus, the cutting edge Tb3 of the tool blade Tb is moved along the predetermined locus as shown in A5 → A6 → A7, and the cutting edge Tb3 is not placed on the tooth surface Wb. As a contact, the cutting edge Tb3 is retracted from the internal space of the tooth groove Wa to the outside of the tooth groove Wa (retraction step). The evacuation process is controlled by the evacuation unit 55 in the control device 50 shown in FIG.

Here, the tooth surface Wb of the workpiece W is an involute curve, whereas the locus of the cutting edge Tb3 of the tool blade Tb is a cycloid curve. Therefore, in the tooth surface processing step, the tooth surface Wb is cut using a portion of the cycloid curve which is the locus of the cutting edge Tb3 of the tool blade Tb, which is close to the involute curve of the tooth surface Wb. This is realized by setting the rotation speed ratio between the workpiece W and the cutting tool T, the cutting edge diameter of the tool blade Tb of the cutting tool T, and the rotation phase adjustment amount of the cutting tool T with respect to the workpiece W.

Further, FIGS. 6 and 7 show a case where one tooth surface Wb in one tooth groove Wa is cut. By performing this operation on all the tooth grooves Wa, one tooth surface Wb in all the tooth grooves Wa can be cut. Further, the other tooth surface Wb can be cut in substantially the same manner by reversing the rotation directions of the workpiece W and the cutting tool T.

According to the above-mentioned cutting method, after the tooth surface processing step, the cutting edge Tb3 of the tool blade Tb is moved from a predetermined locus (cycloid curve) to a different temporary retracted position. By this temporary retracting operation, it is possible to prevent burrs from remaining near the machining end point of the tooth surface Wb. After that, the cutting edge Tb3 of the tool blade Tb returns to the cycloid curve which is a predetermined locus in the return step, and retracts from the internal space of the tooth groove Wa along the predetermined locus. Therefore, in the next machining, the cutting edge Tb3 of the tool blade Tb can move along the predetermined locus again to carry out the tooth surface machining step.

That is, by rotating the workpiece W and the cutting tool T in synchronization with the rotation axis Cw of the workpiece W and the rotation axis Ct of the cutting tool T arranged in parallel, a high-speed cutting speed can be obtained. , It is possible to prevent burrs from remaining due to the temporary evacuation process.

(6. Control example)
(6-1. Basics of control example)
As described in the above-mentioned cutting method, the locus of the cutting edge Tb3 in A1 → A2 → A3 → A5 → A6 → A7 is a cycloid curve. The locus of the cutting edge Tb3 in A3 → A4 → A5 deviates from the cycloid curve. Therefore, the operation in the temporary evacuation step and the return process is corrected with respect to the reference operation by using the locus of the cycloid curve as the reference operation to realize the above operation. An example of a plurality of control methods will be described below.

(6-2. Control method of the first example)
The control method of the first example will be described with reference to FIG. In the control method of the first example, the rotation speed of the cutting tool T is always set to a constant speed Vt. Then, the rotation speed of the workpiece W is set to the reference speed Vw in the tooth surface processing step (T1 to T2) and the retracting step (T4 to T5), and is used in the temporary retracting step (T2 to T3) and the returning step (T3 to T4). The speed is changed from the reference speed Vw.

Specifically, in the temporary evacuation step (T2 to T3), the rotation speed of the workpiece W is increased with respect to the reference speed Vw. That is, the temporary retracting step (T2 to T3) determines the relative rotational speed of the cutting tool T with respect to the rotational speed of the workpiece W as compared with the tooth surface processing step (T1 to T2) and the retracting step (T4 to T5). I'm late.

In the return step (T3 to T4), the rotation speed of the workpiece W is slowed down with respect to the reference speed Vw. That is, in the return step (T3 to T4), the relative rotation speed of the cutting tool T with respect to the rotation speed of the workpiece W is faster than in the tooth surface machining step (T1 to T2) and the retracting step (T4 to T5). is doing. By varying the rotation speed of the workpiece W in this way, the operations of the temporary evacuation steps (T2 to T3) and the return steps (T3 to T4) can be realized.

(6-3. Control method of the second example)
The control method of the second example will be described with reference to FIG. In the control method of the second example, the rotation speed of the workpiece W is always set to a constant speed Vw. Then, the rotation speed of the cutting tool T is set to the reference speed Vt in the tooth surface machining step (T1 to T2) and the retracting step (T4 to T5), and is used in the temporary retracting step (T2 to T3) and the returning step (T3 to T4). The speed is changed from the reference speed Vt.

Specifically, in the temporary evacuation step (T2 to T3), the rotation speed of the cutting tool T is slowed down with respect to the reference speed Vt. That is, the temporary retracting step (T2 to T3) determines the relative rotational speed of the cutting tool T with respect to the rotational speed of the workpiece W as compared with the tooth surface processing step (T1 to T2) and the retracting step (T4 to T5). I'm late.

In the return step (T3 to T4), the rotation speed of the cutting tool T is increased with respect to the reference speed Vt. That is, in the return step (T3 to T4), the relative rotation speed of the cutting tool T with respect to the rotation speed of the workpiece W is faster than in the tooth surface machining step (T1 to T2) and the retracting step (T4 to T5). is doing. By varying the rotation speed of the cutting tool T in this way, the operations of the temporary retracting process (T2 to T3) and the returning process (T3 to T4) can be realized.

(6-4. Control method of the third example)
In the temporary evacuation steps (T2 to T3) and the return steps (T3 to T4), in the first example, only the rotation speed of the workpiece W is changed, and in the second example, only the rotation speed of the cutting tool T is changed. rice field. In addition to this, the rotation speed of the workpiece W and the rotation speed of the cutting tool T may be changed in the temporary evacuation steps (T2 to T3) and the return steps (T3 to T4).

However, the temporary retracting step (T2 to T3) determines the relative rotational speed of the cutting tool T with respect to the rotational speed of the workpiece W as compared with the tooth surface processing steps (T1 to T2) and the retracting process (T4 to T5). Need to be late. Further, in the return steps (T3 to T4), the relative rotation speed of the cutting tool T with respect to the rotation speed of the workpiece W is faster than in the tooth surface processing steps (T1 to T2) and the retracting steps (T4 to T5). There is a need to.

(6-5. Control method of the fourth example)
The control method of the fourth example will be described with reference to FIG. In the control method of the fourth example, the X-axis position of the rotation axis Ct of the cutting tool T is always set to a constant position Xt. Then, the X-axis position of the rotation axis Cw of the workpiece W is set to the reference position Xw in the tooth surface processing step (T1 to T2) and the retracting step (T4 to T5), and the temporary retracting step (T2 to T3) and the returning step (T2 to T3). It is changed from the reference position Xw at T3 to T4).

Specifically, in the temporary evacuation steps (T2 to T3), by moving the X-axis position of the rotation axis Cw of the workpiece W with respect to the reference position Xw, the cutting edge Tb3 is moved to the machining end position of the tooth surface Wb. Separate from. In the return steps (T3 to T4), the X-axis position of the rotation axis Cw of the workpiece W is moved with respect to the reference position Xw to return to a predetermined trajectory (cycloid curve). In this way, by reciprocating the X-axis position of the rotation axis Cw of the workpiece W, the operations of the temporary retract step (T2 to T3) and the return step (T3 to T4) can be realized.

In the temporary retracting steps (T2 to T3) and the returning steps (T3 to T4), the rotation axis Cw of the workpiece W and the rotation axis Ct of the cutting tool T reciprocate while maintaining parallelism. In the above, the movement of the X-axis position has been described as an example, but it may be moved in the direction corresponding to the machining position and the axis configuration.

(6-6. Control method of the fifth example)
The control method of the fifth example will be described with reference to FIG. In the control method of the fifth example, the X-axis position of the rotation axis Cw of the workpiece W is always set to a constant position Xw. Then, the X-axis position of the rotation axis Ct of the cutting tool T is set to the reference position Xt in the tooth surface processing step (T1 to T2) and the retracting step (T4 to T5), and the temporary retracting step (T2 to T3) and the returning step (T2 to T3). It is changed from the reference position Xt at T3 to T4).

Specifically, in the temporary evacuation step (T2 to T3), by moving the X-axis position of the rotation axis Ct of the cutting tool T with respect to the reference position Xt, the cutting edge Tb3 is moved to the machining end position of the tooth surface Wb. Separate from. In the return steps (T3 to T4), the X-axis position of the rotation axis Ct of the cutting tool T is moved with respect to the reference position Xt to return to a predetermined locus (cycloid curve). In this way, by reciprocating the X-axis position of the rotation axis Ct of the cutting tool T, the operations of the temporary retracting process (T2 to T3) and the returning process (T3 to T4) can be realized.

(6-7. Control method of the sixth example)
In the temporary retracting process (T2 to T3) and the returning process (T3 to T4), in the fourth example, only the rotation axis Cw of the workpiece W is reciprocated, and in the fifth example, only the rotation axis Ct of the cutting tool T is moved. Was moved back and forth. In addition to this, in the temporary evacuation steps (T2 to T3) and the return steps (T3 to T4), the rotation axis Cw of the workpiece W and the rotation axis Ct of the cutting tool T may be reciprocated.

(7. Machining condition determination process)
The processing for determining processing conditions will be described with reference to FIG. As described above, it is necessary to find a portion of the cycloid curve of the cutting edge Tb3 of the tool blade Tb that is close to the involute curve of the tooth surface Wb. Further, in the cycloid curve, it is necessary to have a positional relationship between the workpiece W and the cutting tool T such that the cutting edge Tb3 of the tool blade Tb cuts from the tooth tip of the tooth surface Wb toward the tooth bottom. Further, it is necessary to cut the tooth surface Wb for all of the plurality of tooth grooves Wa in the workpiece W. In order to realize these things, the machining conditions are determined by the machining condition determination process as described below.

As shown in FIG. 12, the number of blades of the cutting tool T is determined (step S1). For example, the cutting tool T shown in FIG. 2 has one blade number. The number of blades is preferably 1, 2, or 3, for example. Next, the rotation speed ratio between the workpiece W and the cutting tool T is determined (step S2). That is, the condition that the tool blade Tb can cut all the tooth surface Wb is determined. The tool blade Tb determines the rotation speed ratio for cutting all tooth surfaces Wb once.

Next, the initial value of the blade tip diameter of the tool blade Tb is input (step S3). Next, under the condition that the workpiece W is fixed, the cutting edge Tb3 of the tool blade Tb is calculated as a cycloid motion locus by using the rotation speed ratio and the cutting edge diameter of the tool blade Tb (step S4).

Next, it is determined whether or not the cycloid curve, which is the locus of the cutting edge Tb3 of the tool blade Tb, matches the tooth surface Wb, which is the involute curve (step S5). If they do not match (S5: No), the blade tip diameter of the tool blade Tb is changed (step S6). Then, steps S4 and S5 are repeated.

If they match in step S5 (S5: Yes), the blade tip diameter of the tool blade Tb at that time is determined (step S7). Using the determined blade edge diameter of the tool blade Tb and the rotation speed ratio, a part of the cycloid curve of the blade edge Tb3 of the tool blade Tb and the involute curve in the radial range of the workpiece W where the tooth surface Wb exists. It will be similar to a certain tooth surface Wb.

Next, the rotation phase adjustment amount is determined so that the locus of the cutting edge Tb3 of the tool blade Tb cuts from the tooth tip of the tooth surface Wb toward the tooth bottom (step S8). Depending on the relationship between the rotation phase of the workpiece W and the rotation phase of the cutting tool T, the tool blade Tb enters the internal space of the tooth groove Wa in a non-contact manner with the tooth surface Wb, and then the tooth does not contact the tooth surface Wb. It may be retracted from the internal space of the groove Wa. Further, depending on the rotation phase, the tool blade Tb may not contact the tooth surface Wb when entering the internal space of the tooth groove Wa, and may contact the tooth surface Wb when retracting from the internal space of the tooth groove Wa. be. Further, depending on the rotation phase, the tool blade Tb may not be able to enter the tooth groove Wa and may collide with the tooth. Therefore, the rotation phase adjustment amount that realizes the operation as shown in FIGS. 6 and 7 is determined. In this way, the processing conditions are determined.

According to the gear processing method described above, although only one surface of the tooth surface Wb is cut, the cutting speed can be made higher than that of skiving processing or hobbing processing. Therefore, even if a cutting tool T having a small diameter is used, the tooth surface Wb can be cut with high accuracy. In particular, in the cutting process of the internal gear, the outer diameter of the cutting tool T is restricted, which is effective.

1: Machine tool, 10: Bed, 20: Work piece holding device, 21: X-axis moving table, 22: B-axis rotary table, 23: Work piece spindle device, 23a: Work piece spindle base, 23b: Work piece spindle Housing, 23c: Machine tool spindle, 30: Tool holding device, 31: Column, 32: Saddle, 33: Tool spindle device, 33a: Tool spindle housing, 33b: Tool spindle, 50: Control device, 51: Machining condition storage unit , 52: Tooth surface processing part, 53: Temporary retracting part, 54: Returning part, 55: Retracting part, 60: Drive device, Ct: Rotating axis, Cw: Rotating axis, T: Cutting tool, Ta: Tool body, Tb : Tool blade, Tb1: Tip surface, Tb2: Side surface, Tb3: Cutting edge, W: Machine tool, Wa: Tooth groove, Wb: Tooth surface

Claims (7)

This is a gear processing method for processing the tooth surface in the tooth groove of the tooth profile on a gear-shaped workpiece having a tooth profile formed in advance.
By rotating the workpiece and the cutting tool synchronously with the rotation axis of the workpiece and the rotation axis of the cutting tool arranged in parallel, the cutting edge of the cutting tool is aligned with a predetermined trajectory with respect to the workpiece. And a tooth surface processing step of processing one of the tooth surfaces in each of the tooth grooves from the tooth tip of the tooth surface toward the tooth bottom.
Temporary evacuation step of moving the cutting edge of the cutting tool to a temporary evacuation position that is a non-contact position with the tooth surface in the internal space of the tooth groove and is different from the predetermined locus when the machining end point of the tooth surface is reached. When,
A return step of returning the cutting edge of the cutting tool from the temporary retracted position to the predetermined locus in the internal space of the tooth groove, and a return step.
After returning to the predetermined locus, the cutting tool's cutting edge is moved along the predetermined locus, and the cutting tool's cutting edge is retracted from the internal space of the tooth groove to the outside of the tooth groove.
A gear processing method. In the temporary retracting step, when the machining end point of the tooth surface is reached in the tooth surface machining step, the cutting edge of the cutting tool is relatively moved in the internal space of the tooth groove in the circumferential direction of the workpiece. The gear processing method according to claim 1, wherein the gear is moved to the temporary retracted position. The predetermined trajectory is a cycloid curve.
The tooth surface is an involute curve and has an involute curve.
The gear processing method according to claim 1 or 2, wherein the tooth surface processing step processes the tooth surface using a portion of the cycloid curve that is close to the involute curve. The tooth surface processing step is
By setting the rotation speed ratio between the work piece and the cutting tool, the cutting edge diameter of the cutting tool, and the rotation phase adjustment amount of the cutting tool with respect to the work piece.
The gear processing method according to claim 3, wherein the tooth surface is processed by using a portion of the cycloid curve that is close to the involute curve. The temporary retracting step slows down the relative rotational speed of the cutting tool with respect to the rotational speed of the workpiece as compared with the tooth surface processing step and the retracting step.
The return step is described in any one of claims 1-4, which increases the relative rotation speed of the cutting tool with respect to the rotation speed of the workpiece as compared with the tooth surface processing step and the retracting step. Gear processing method. The gear processing method according to any one of claims 1-4, wherein the temporary retracting step and the returning step move the rotating axis of the cutting tool back and forth relative to the rotating axis of the workpiece. A gear processing device that processes the tooth surface in the tooth groove of the tooth profile on a gear-shaped workpiece having a tooth profile formed in advance.
Cutting tools and
A control device that controls the workpiece and the cutting tool,
Equipped with
The control device is
By rotating the work piece and the cutting tool synchronously with the rotation axis of the work piece and the rotation axis of the cutting tool arranged in parallel, the cutting edge of the cutting tool is set to a predetermined trajectory with respect to the work piece. A tooth surface processing portion that moves along the tooth surface and processes one of the tooth surfaces in each tooth groove from the tooth tip of the tooth surface toward the tooth bottom.
When the machining end point of the tooth surface is reached, the cutting edge of the cutting tool is moved to a temporary evacuation position that is a non-contact position with the tooth surface in the internal space of the tooth groove and is different from the predetermined locus. When,
A return portion that returns the cutting edge of the cutting tool from the temporary retracted position to the predetermined locus in the internal space of the tooth groove.
After returning to the predetermined locus, the cutting tool's cutting edge is moved along the predetermined locus, and the cutting tool's cutting edge is retracted from the internal space of the tooth groove to the outside of the tooth groove.
A gear processing device.

Images