JP7268329B2 - Gear processing device and gear processing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a gear machining apparatus and a gear machining method.

Gear processing methods include pinion processing and gear skiving processing. In a machining tool (pinion cutter) used for pinion machining, as described in Patent Document 1, by setting the rake angle of the rake face of the tool blade to a negative value, the cutting surface of the workpiece is prevented from peeling. There is something that can prevent the occurrence of Further, as described in Patent Document 2, there is a tool that can improve cutting efficiency by providing a rake face of a tool edge with a horizontal rake angle.

In gear skiving, a machining tool (skiving cutter) having a plurality of tool blades on the outer circumference is used to set the central axis of the machining tool at an angle (crossing) with respect to an axis parallel to the central axis of the workpiece. angle). In this method, the skiving cutter and the workpiece are synchronously rotated, and the workpiece is cut by moving the skiving cutter straight along the central axis of the workpiece. In some skiving cutters, as described in Patent Document 3, the clearance angle of the flank face of the tool blade is set to be negative to increase the rake angle of the rake face and prevent the strength of the cutting edge from being lowered.

JP 2017-104910 A JP-A-62-102961 JP 2014-161972 A

For example, assume a workpiece W as shown in FIG. 6A. That is, in this workpiece W, a large-diameter cylindrical member Wa and a small-diameter cylindrical member Wb are coaxially integrated in the central axis Zw direction. Further, a medium-diameter cylindrical member Wc having a diameter smaller than that of the large-diameter cylindrical member Wa and larger than that of the small-diameter cylindrical member Wb is coaxially integrated with the small-diameter cylindrical member Wb in the central axis Zw direction.

When the gear teeth Wg are formed on the outer circumference of the medium-diameter cylindrical member Wc of the workpiece W by gear skiving, the length b of the small-diameter cylindrical member Wb in the direction of the central axis Zw is equal to that of the machining tool T1. It is necessary that the blade Ta1 does not interfere with the end surface Waa of the large-diameter cylindrical member Wa on the side of the small-diameter cylindrical member Wb, and that the tool blade of the processing tool T1 completely forms the tooth profile of the tooth Wg before coming out. be. Conventionally, since the length b of the small-diameter cylindrical member Wb in the direction of the central axis Zw is set to be large, the shape and weight of the workpiece W tend to increase.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and provides a gear machining apparatus and a gear machining method that can reduce the removal allowance of a tool edge of a machining tool when creating a gear by gear skiving. for the purpose.

According to one aspect of the present invention, the center axis of a machining tool having a plurality of tool edges on its outer periphery forms an angle (intersecting angle) with respect to an axis parallel to the center axis of a workpiece,
While synchronizing the rotation of the workpiece around the central axis of the workpiece and the rotation of the machining tool around the central axis of the machining tool,
A gear machining apparatus comprising a control device for generating a gear on the workpiece by feeding the machining tool to the workpiece in the central axis direction of the workpiece,
The control device is
The rake angle is set to a negative angle so that the included angle of the tool edge of the machining tool is an obtuse angle, and the sharpening angle attached to the tool edge is set to an angle different from the helix angle of the tool edge. a tool design department that designs a machining tool having a negative rake angle;
a machining control unit for machining the workpiece with a machining tool having a negative rake angle to create the gear;
with
In the processing tool, a tool reference point is defined as the intersection of a plane orthogonal to the center axis of the processing tool and including the cutting edges of the plurality of tool blades and the center axis of the processing tool,
When the workpiece and the machining tool are relatively moved, one continuous removal portion by one tool blade in one tooth groove of the workpiece is defined as a unit removal portion,
When the tool reference point is aligned with the axial end face on the machining end side of the gear generating portion of the workpiece, the portion of the unit removed portion located in the tooth space of the workpiece is defined as the actual removed portion. and when defining a portion of the unit removed portion located outside the tooth space of the workpiece as a virtual removed portion,
The tool design department
When the sharpening angle attached to the tool blade is set to an angle different from the helix angle of the tool blade, the length of the actual removed portion (C2) is determined by the sharpening angle applied to the tool blade and the twist angle of the tool blade. A gear machining device that sets a sharpening angle attached to the tool blade with respect to the helix angle of the tool blade so as to be shorter than the actual length (C1) of the removed portion when set to the same angle as the angle. .

Another aspect of the present invention is to make the central axis of a processing tool having a plurality of tool edges on the outer periphery to have an angle (intersecting angle) with respect to an axis parallel to the central axis of the workpiece,
While synchronizing the rotation of the workpiece around the central axis of the workpiece and the rotation of the machining tool around the central axis of the machining tool,
A gear machining method for generating a gear on the workpiece by feeding the machining tool to the workpiece in the central axis direction of the workpiece,
The rake angle of the tool edge of the machining tool is set to a negative angle, and the sharpening angle attached to the tool edge is set to an angle different from the helix angle of the tool edge, so that the rake angle is negative. a tool design process for designing a tool;
a machining control step of machining the workpiece with a machining tool having a negative rake angle to create the gear;
with
In the processing tool, a tool reference point is defined as the intersection of a plane orthogonal to the center axis of the processing tool and including the cutting edges of the plurality of tool blades and the center axis of the processing tool,
When the workpiece and the machining tool are relatively moved, one continuous removal portion by one tool blade in one tooth groove of the workpiece is defined as a unit removal portion,
When the tool reference point is aligned with the axial end face on the machining end side of the gear generating portion of the workpiece, the portion of the unit removed portion located in the tooth space of the workpiece is defined as the actual removed portion. and when defining a portion of the unit removed portion located outside the tooth space of the workpiece as a virtual removed portion,
The tool design process includes:
When the sharpening angle attached to the tool blade is set to an angle different from the helix angle of the tool blade, the length of the actual removed portion (C2) is determined by the sharpening angle applied to the tool blade and the twist angle of the tool blade. Gear machining method, wherein the sharpening angle attached to the tool blade with respect to the helix angle of the tool blade is set so as to be shorter than the actual length (C1) of the removed portion when set to the same angle as the angle. It is in.

According to the gear machining apparatus and the gear machining method of the present invention, the rake angle of the tool edge of the machining tool can be set to a negative angle to change the tool locus of the machining tool. The shape of the part removed by the tool can be varied. Therefore, it is possible to reduce the clearance of the tool edge of the machining tool, and it is possible to reduce the size and weight of the workpiece.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the outline of the gear processing apparatus of this embodiment. 2 is a flowchart for explaining processing of a tool design unit of the control device of FIG. 1; FIG. 2 is a flowchart for explaining processing of a processing control unit of the control device of FIG. 1; FIG. 1 is a perspective view showing an outline of a working tool used in gear skiving; FIG. FIG. 3 is a partial cross-sectional view of a general machining tool used in gear skiving as viewed from the Xt direction. FIG. 4 is a partial cross-sectional view of the machining tool of the present embodiment used in gear skiving as seen from the Xt direction. FIG. 4 is a diagram showing the positional relationship between a general machining tool and a multi-stage workpiece before gear skiving. FIG. 5 is a diagram showing the positional relationship between a general machining tool and a multi-stage workpiece immediately before the completion of machining of one tooth space during gear skiving machining. FIG. 6B is a diagram showing a portion removed by one feed of one tool blade in one tooth space in the tooth space direction when the machining tool of FIG. 5A is in the position of FIG. 6B. FIG. 6B is a diagram showing a portion removed by one feed of one tool blade in one tooth space in the tooth space direction when the machining tool of FIG. 5B is in the position of FIG. 6B. It is a figure which shows the state which overlapped FIG. 7A and FIG. 7B. FIG. 4 is a diagram showing variables of formulas used in tool design in correspondence with machining tools. FIG. 4 is a view of the positional relationship between the machining tool and the workpiece during gear skiving machining, viewed in the radial direction of the workpiece. FIG. 2 is a view of the positional relationship between a machining tool and a workpiece during gear skiving, as seen in the central axis direction of the workpiece;

(1. Machine configuration of gear processing device)
In this embodiment, a 5-axis machining center capable of gear skiving will be described as an example of a gear machining apparatus with reference to FIG. That is, the gear machining apparatus 1 has, as drive axes, three rectilinear axes (X, Y, and Z axes) orthogonal to each other and two rotary axes (A axis parallel to the X axis and C axis perpendicular to the A axis). ).

As shown in FIG. 1, the gear machining apparatus 1 includes a bed 10, a column 20, a saddle 30, a rotary spindle 40, a table 50, a tilt table 60, a turntable 70, a workpiece holder 80, a control device 100, and the like. Although not shown, a known automatic tool changer is provided alongside the bed 10 .

Bed 10 is arranged on the floor. An X-axis ball screw (not shown) is arranged on the upper surface of the bed 10 for driving the column 20 in the X-axis direction. The bed 10 is provided with an X-axis motor 11c for rotationally driving the X-axis ball screw. A Y-axis ball screw (not shown) for driving the saddle 30 in the Y-axis direction is arranged on a side surface (sliding surface) 20a of the column 20 parallel to the Y-axis. The column 20 is provided with a Y-axis motor 23c that rotationally drives the Y-axis ball screw.

The rotary spindle 40 supports the machining tool T, is rotatably supported in the saddle 30 , and is rotated by a spindle motor 41 accommodated in the saddle 30 . A machining tool (skiving cutter) T for gear skiving is held by a tool holder (not shown) and fixed to the tip of the rotation main shaft 40, and rotates as the rotation main shaft 40 rotates. Further, the machining tool T moves in the X-axis direction and the Y-axis direction with respect to the bed 10 as the column 20 and the saddle 30 move. Details of the processing tool T will be described later.

Furthermore, a Z-axis ball screw (not shown) is arranged on the upper surface of the bed 10 for driving the table 50 in the Z-axis direction. A Z-axis motor 12c that rotationally drives the Z-axis ball screw is arranged on the bed 10 . A tilt table support portion 63 that supports the tilt table 60 is provided on the upper surface of the table 50 . The tilt table 60 is provided on the tilt table support portion 63 so as to be rotatable (swingable) about the A axis. The tilt table 60 is rotated (swinged) by an A-axis motor 61 accommodated in the table 50 .

A turntable 70 is provided on the tilt table 60 so as to be rotatable around the C-axis. A workpiece holder 80 for holding a workpiece W is attached to the turntable 70 . The turntable 70 is rotated by the C-axis motor 62 together with the workpiece W and workpiece holder 80 .

The control device 100 includes a machining control section 101, a tool design section 102, a storage section 103, and the like. Here, the machining control unit 101, the tool design unit 102, and the storage unit 103 can each be configured by separate hardware, or can be configured by software.

The machining control unit 101 drives and controls the spindle motor 41 to rotate the machining tool T. As shown in FIG. Further, the X-axis motor 11c, Z-axis motor 12c, and Y-axis motor 23c are driven and controlled to relatively move the machining tool T and the workpiece W in the X-axis direction, the Z-axis direction, and the Y-axis direction. Gear skiving of the workpiece W is performed by controlling the driving of the A-axis motor 61 and the C-axis motor 62 to relatively rotate the workpiece W and the machining tool T about the A axis and the C axis. conduct.

Specifically, the machining control unit 101 drives and controls the C-axis motor 62 so that the rotation axis Lw of the workpiece W and the rotation axis Lt of the machining tool T are set at a predetermined intersection angle φ (see FIG. 9A). set. Then, the spindle motor 41 and the A-axis motor 61 are controlled to rotate the machining tool T and the workpiece W synchronously. Then, the X-axis motor 11c, the Z-axis motor 12c, and the Y-axis motor 23c are driven and controlled to relatively move the machining tool T in the rotation axis direction (C-axis direction) of the workpiece W, thereby adjusting the gear sky of the workpiece W. Bing processing is performed.

The tool design unit 102 obtains specifications of the processing tool T and designs the processing tool T, details of which will be described later.
The storage unit 103 stores tool data related to the machining tool T, that is, cutting edge circle diameter da, reference circle diameter d, cutting edge height ha, module m, shift coefficient λ, pressure angle α, front pressure angle αt, and cutting edge pressure angle αa, the number of teeth Z of the tool edge Ta, etc., and machining data for cutting the workpiece W are stored in advance. The storage unit 103 also stores shape data of the machining tool T designed by the tool design unit 102 .

(2. Processing tools)
As shown in FIGS. 4 and 5A, a general machining tool T1 for gear skiving has a plurality of tool edges Ta1 on the outer periphery, and is rotatably supported around the central axis Zt of the machining tool T1. be done. Each tool edge Ta1 is formed as a ridge. The tool edge Ta1 has a twist angle γt1 with respect to the center axis Zt of the machining tool T1. However, the tool edge Ta1 may be formed so that the torsion angle γt1 is zero. A radial outer surface Tc1 of the tool edge Ta1 is inclined with respect to the central axis Zt. That is, the circumscribed surface of the tool edge Ta1 is formed in a conical shape. The inclination angle ξb1 of the radial outer surface Tc1 of the tool edge Ta1 corresponds to the clearance angle in cutting.

Moreover, the rake face Tb1 of the tool edge Ta1 is inclined by an angle ξa1 in the radial direction with respect to a plane perpendicular to the center axis Zt. The inclination angle ξa1 of the rake face Tb1 of the tool edge Ta1 corresponds to the rake angle in cutting. Furthermore, the rake face Tb1 of the tool edge Ta1 is inclined by an angle ξc1 in the circumferential direction with respect to the plane perpendicular to the center axis Zt. The inclination angle ξc1 of the rake face Tb1 of the tool edge Ta1 corresponds to the sharpening angle. However, the tool edge Ta1 may be formed so that the sharpening angle ξc1 is zero.

Here, as described in Background Art, when gear skiving is used to create gear teeth Wg on the outer circumference of the medium-diameter cylindrical member Wc of the workpiece W shown in FIG. The length b is such that the tool edge Ta1 of the processing tool T1 does not interfere with the end surface Waa of the large-diameter cylindrical member Wa, and the tool edge Ta1 of the processing tool T1 completely forms the tooth profile of the gear before coming out. must be set to

The inventors of the present application have found that the length b of the small-diameter cylindrical member Wb in the direction of the central axis Zw can be reduced by simulating gear machining. Specifically, as shown in FIG. 6B corresponding to FIG. 6A, the central axis Zt of the machining tool T1 has an intersection angle θ with respect to an axis parallel to the central axis Zw of the workpiece W. That is, it means that the center axes Zt and Zw of both are not parallel.

The crossing angle θ is expressed by the difference between the helix angle γt1 of the tool edge Ta1 of the working tool T1 and the helix angle γw of the tooth Wg of the gear formed on the medium-diameter cylindrical member Wc of the workpiece W. Therefore, when the machining tool T1 reaches the position shown in FIG. 6B, part of the tool edge Ta1 protrudes from the end face Wcc of the medium-diameter cylindrical member Wc by the length a in the direction of the center axis Zt.

The position of the processing tool T1 shown in FIG. 6B is defined as follows. That is, a plane S1 that is perpendicular to the center axis Zt and includes the cutting edge of each tool edge Ta1 is set. Then, an intersection Q1 between the plane S1 and the central axis Zt (hereinafter referred to as "the intersection Q1 of the machining tool T1", see also FIG. 5A) is set. The position of the processing tool T1 shown in FIG. 6B is the position when the intersection point Q1 of the processing tool T1 coincides with the end surface Wcc of the medium-diameter cylindrical member Wc on the processing end side.

Further, when the intersection Q1 of the processing tool T1 coincides with the end surface Wcc of the medium-diameter cylindrical member Wc, the tooth groove (the portion between the teeth Wg and Wg) of the medium-diameter cylindrical member Wc is formed as shown in FIG. 7A. It is in a good processing state. That is, the halftone line portion A1 shown between the contours Wgg of the tooth spaces in FIG. 7A is the portion removed by the processing tool T1 when the intersection point Q1 of the processing tool T1 and the end surface Wcc of the medium-diameter cylindrical member Wc coincide with each other. is shown.

A meshed portion Au1 above the end surface Wcc of the medium-diameter cylindrical member Wc indicates a virtual removed portion, and the tip side of the tool edge Ta1 is in a state of being removed from the tooth space. A meshed portion Ad1 below the end surface Wcc of the medium-diameter cylindrical member Wc indicates the actual removed portion, and the rear end side of the tool edge Ta1 remains in the tooth groove. Therefore, the removal allowance of the tool edge Ta1 is the distance c1 in the central axis Zw direction from the end surface Wcc of the medium-diameter cylindrical member Wc to the lowest point P1 of the lower halftone portion Ad.

From the above, the length b of the small-diameter cylindrical member Wb in the direction of the central axis Zw is represented by the sum (a+c1) of the projection length a of the tool edge Ta1 and the clearance c1 of the tool edge Ta1. Therefore, in order to reduce the length b of the small-diameter cylindrical member Wb in the direction of the central axis Zw, the projection length a of the tool edge Ta1 or the clearance c1 of the tool edge Ta1 should be reduced.

The protruding length a of the tool edge Ta1 can be changed by changing the outer diameter and intersection angle θ of the processing tool T1, but the outer diameter and intersection angle θ of the processing tool T1 are limited. The removal allowance c1 of the tool edge Ta1 can be obtained by changing the tool specifications of the machining tool T1. That is, when the tool specification of the processing tool T1 is changed, the tool locus of the processing tool T1 is changed, so that the shape of the portion to be removed by the processing tool T1 can be changed. Therefore, in the present embodiment, this problem is addressed by reducing the removal allowance c1 of the tool edge Ta1.

This can be handled by using a processing tool T2 (hereinafter referred to as "second processing tool T2") shown in FIG. 5B. In this second processing tool T2, the rake angle ξa2 of the rake face Tb2 is set to a negative angle so that the included angle of the tool edge Ta2 becomes an obtuse angle, and the sharpening angle ξc2 is set to an angle different from the helix angle γt2. do. In the following description, the machining tool T1 having the rake angle ξa1 of the rake face Tb1 shown in FIG. It is called tool T1. Also, in FIG. 5B, the same parts as in FIG. 5A are indicated by changing only the suffix number from 1 to 2, and detailed description thereof will be omitted.

FIG. 7B shows the intermediate cylindrical member Wc when the intersection point Q2 of the second processing tool T2 (similar to the intersection point Q1 of the first processing tool T1, see FIG. 5B) coincides with the end face Wcc of the intermediate cylindrical member Wc. 7A (in the case of the first machining tool T1). In addition, in FIG. 7B, the same parts as in FIG. 7A are shown by changing only the suffix number from 1 to 2, and detailed description thereof will be omitted. As is clear from FIG. 7C in which FIGS. 7A and 7B are superimposed, the removal allowance c2 of the tool edge Ta2 of the second processing tool T2 is greater than the removal allowance c1 of the tool edge Ta1 of the first processing tool T2. It is reduced by the length cc.

Here, the rake angle ξa2 of the tool edge Ta2 of the second machining tool T2 is set to an angle equal to or less than the intersection angle θ. The reason for this is that if the rake angle ξa2 of the tool edge Ta2 of the second processing tool T2 is set to be larger than the intersection angle θ, the protruding length of the tool edge Ta2 of the second processing tool T2 is reduced to that of the first processing tool T2. This is because the protruding length a of the tool edge Ta1 of T1 cannot be the same and becomes longer than a, making it difficult to reduce the clearance c2 of the tool edge Ta2 of the second machining tool T2.

In addition, the sharpening angle ξc2 of the tool edge Ta2 of the second processing tool T2 is such that, of the left and right blade surfaces of the tool edge Ta2, the blade surface on the machining start side (the leading blade surface, the left blade surface in FIG. direction. The reason for this is that the leading blade face can reliably cut into the workpiece W at the start of machining.

The reason why the clearance c2 of the tool edge Ta2 of the second processing tool T2 can be reduced by setting the sharpening angle ξc2 of the tool edge Ta2 of the second processing tool T2 to an angle different from the torsion angle γt2 is as follows. can be thought of as In gear skiving, in principle, the cutting state differs at each part of the rake face Tb2 (Tb1) of the second machining tool T2 (first machining tool T1).

However, by setting the sharpening angle ξc2 of the tool edge Ta2 of the second machining tool T2 to an angle different from the torsion angle γt2, the cutting force acting on the leading edge and the trailing edge (the edge on the end of machining) It is possible to balance the cutting force applied to. Therefore, the length cc in FIG. 7C can be increased, and the removal allowance c2 of the tool edge Ta2 of the second processing tool T2 can be made smaller than the removal allowance c1 of the tool edge Ta1 of the first processing tool T1.

However, since the rake angle ξa2 of the second machining tool T2 is a negative angle, the tool edge Ta2 is easily worn, and the cutting conditions are disadvantageous compared to the first machining tool T1. Therefore, first, in the gear machining of this embodiment, rough machining is performed using the first machining tool T1 until the intersection Q1 of the first machining tool T1 and the end surface Wcc of the medium-diameter cylindrical member Wc coincide. Next, using the second machining tool T2, finish machining is performed until the tool edge Ta2 is completely removed from the end surface Wcc of the medium-diameter cylindrical member Wc. Thereby, the wear of the tool edge Ta2 of the second machining tool T2 can be suppressed, and the machining efficiency can be improved.

According to the second processing tool T2 as described above, the rake angle ξa2 of the tool edge Ta2 of the second processing tool T2 is set to a negative angle to change the tool locus of the second processing tool T2. Therefore, the shape of the portion of the workpiece W to be removed by the second machining tool T2 can be changed. Therefore, the removal allowance c2 of the tool edge Ta2 of the second machining tool T2 can be reduced, and the size and weight of the workpiece W can be reduced. And, the shape of the workpiece that can be processed increases.

Here, if the width of the cutting edge of the tool edge Ta1 of the first machining tool T1 is small, the cutting edge is deformed during machining, chattering vibration occurs, and there is a problem that the machining accuracy is lowered. Therefore, in designing the first machining tool T1, a predetermined threshold value for the width of the cutting edge is set so that the width of the cutting edge is greater than or equal to the threshold value. The above also applies to the second processing tool T2. An example of calculation for obtaining the cutting edge width will be described below, taking the first machining tool T1 as an example.

As shown in FIG. 8, the edge width Sa of the tool edge Ta1 is represented by the edge circle diameter da and the half angle Ψa of the edge circle thickness (see formula (1)).

The cutting edge circle diameter da is represented by the reference circle diameter d and the cutting edge height ha (see formula (2)). and module m (see formula (3)), and the edge height ha is represented by the shift coefficient λ and module m (see formula (4)).

Also, the half angle Ψa of the edge circular edge thickness is expressed by the number of teeth Z of the tool edge Ta1, the shift coefficient λ, the pressure angle α, the front pressure angle αt, and the edge pressure angle αa (see formula (5)). The front pressure angle αt can be expressed by the pressure angle α and the torsion angle γt1 of the tool edge Ta (see formula (6)), and the cutting edge pressure angle αa is the front pressure angle αt, the edge circle diameter da, and the reference circle It can be represented by the diameter d (see equation (7)).

(3. Processing by Tool Design Department of Control Device)
Next, processing (tool design process, gear machining method) by the tool design section 102 of the control device 100 will be described with reference to FIG. Since the design processing of the first processing tool T1 and the second processing tool T2 is the same, the first processing tool T1 will be described as an example. Further, the data on the first processing tool T1, that is, the cutting edge circle diameter da, the reference circle diameter d, the cutting edge height ha, the module m, the shift coefficient λ, the pressure angle α, the front pressure angle αt, and the cutting edge pressure angle αa are It is assumed that it is stored in advance in the storage unit 103 .

The tool design unit 102 of the control device 100 stores the number of teeth Z of the tool edge Ta1 of the first machining tool T1 input by the operator in the storage unit 103 (step S1 in FIG. 2). Then, the tool design unit 102 stores the intersection angle θ between the center axis (rotational axis) Zt of the first machining tool T1 and the center axis (rotational axis) Zw of the workpiece W input by the operator in the storage unit 103. The torsion angle γt1 of the tool edge Ta1 of the first machining tool T1 is obtained based on this intersection angle θ (step S2 in FIG. 2).

The tool design unit 102 obtains the edge width Sa of the tool edge Ta1 based on the stored number of teeth Z and the obtained torsion angle γt1 (step S3 in FIG. 2). Then, the tool design unit 102 reads the threshold value of the cutting edge width Sa stored in advance from the storage unit 103, and determines whether or not the obtained cutting edge width Sa is equal to or greater than the threshold value (step S4 in FIG. 2).

When the determined blade edge width Sa is less than the threshold value, the tool design unit 102 returns to step S1 and repeats the above-described processing. Based on the number Z, the shape of the first machining tool T1 is determined (step S5 in FIG. 2). Then, the tool design unit 102 stores the determined shape of the first machining tool T1 in the storage unit 103, and completes all the processing.

(4. Processing by processing control unit of control device)
Next, processing (machining control process, gear machining method) by the machining control unit 101 of the control device 100 will be described with reference to FIGS. 3 and 9A and 9B. Here, the operator manufactures the first processing tool T1 and the second processing tool T2 based on the respective shape data of the first processing tool T1 and the second processing tool T2 designed by the tool design section 102. and arranged in the automatic tool changer of the gear machining apparatus 1. It is also assumed that the workpiece W is attached to the workpiece holder 80 of the gear machining apparatus 1 .

The machining control unit 101 of the control device 100 mounts the first machining tool T1 to the tip of the rotating main shaft 40 with the automatic tool changer (step S11 in FIG. 3). Then, as shown in FIGS. 9A and 9B, the machining control unit 101 moves the first machining tool so that the intersection angle between the rotation axis Zt of the first machining tool T1 and the rotation axis Zw of the workpiece W becomes θ. Place T1 and workpiece W (step S12 in FIG. 3).

The machining control unit 101 feeds (moves) the first machining tool T1 in the direction of the rotation axis Zw of the workpiece W while synchronously rotating the first machining tool T1 and the workpiece W, thereby forming a medium-diameter cylindrical member. The peripheral surface of Wc is rough-machined to form external teeth (step S13 in FIG. 3). Then, it is determined whether or not the rough machining of the peripheral surface of the medium-diameter cylindrical member Wc has been completed (step S14 in FIG. 3). Returning to S13, the above processing is repeated.

On the other hand, in step S14, when the rough machining of the peripheral surface of the medium-diameter cylindrical member Wc is completed, the machining control unit 101 replaces the first machining tool T1 with the second machining tool T2 in the automatic tool changer. (Step S15 in FIG. 3). Then, the second machining tool T2 and the workpiece W are arranged so that the intersection angle between the rotation axis Zt of the second machining tool T2 and the rotation axis Zw of the workpiece W is θ (step S16 in FIG. 3). .

The machining control unit 101 feeds (moves) the second machining tool T2 in the direction of the rotation axis Zw of the workpiece W while synchronously rotating the second machining tool T2 and the workpiece W, thereby forming a medium-diameter cylindrical member. The external teeth formed on the peripheral surface of Wc are finished (step S17 in FIG. 3). Then, it is determined whether or not finishing of the external teeth formed on the peripheral surface of the medium-diameter cylindrical member Wc is completed (step S18 in FIG. 3), and the external teeth formed on the peripheral surface of the medium-diameter cylindrical member Wc are finished. If the processing has not been completed, the process returns to step S17 and repeats the above processing. On the other hand, in step S18, the processing control unit 101 completes all the processing when finishing rough processing of the external teeth formed on the peripheral surface of the medium-diameter cylindrical member Wc is completed.

(5. Others)
In the above-described embodiment, the case where the first machining tool T1 is used for rough machining and the second machining tool T2 is used for finish machining has been described. Machining and finishing may be performed. Moreover, although the case where the workpiece W is gear skived by moving the machining tools T1 and T2 in the direction of the central axis Zw of the workpiece W has been described, the workpiece W is moved along the central axis Zt of the machining tools T1 and T2. You may make it move to a direction and perform a gear skiving process. In addition, although the case of generating the gear teeth Wg on the outer peripheral surface of the workpiece W has been described, the present invention can also be applied to the generation of each tooth such as a stepped gear, a blind hole gear, and a double helical gear.

1: Gear processing device 100: Control device 101: Machining control unit 102: Tool design unit 103: Storage unit T, T1, T2: Machining tools Ta1, Ta2: Tool blades Tb1, Tb2: Scoops W: workpiece θ: crossing angle γt1, γt2: helix angle of tool edge γw: helix angle of workpiece ξa1, ξa2: rake angle ξc1, ξc2: sharpening angle

Claims (5)

A state in which the central axis of a processing tool having a plurality of tool edges on the outer periphery is at an angle (intersecting angle) with respect to an axis parallel to the central axis of the workpiece,
While synchronizing the rotation of the workpiece around the central axis of the workpiece and the rotation of the machining tool around the central axis of the machining tool,
A gear machining apparatus comprising a control device for generating a gear on the workpiece by feeding the machining tool to the workpiece in the central axis direction of the workpiece,
The control device is
The rake angle is set to a negative angle so that the included angle of the tool edge of the machining tool is an obtuse angle, and the sharpening angle attached to the tool edge is set to an angle different from the helix angle of the tool edge. a tool design department that designs a machining tool having a negative rake angle;
a machining control unit for machining the workpiece with a machining tool having a negative rake angle to create the gear;
with
In the processing tool, a tool reference point is defined as the intersection of a plane orthogonal to the center axis of the processing tool and including the cutting edges of the plurality of tool blades and the center axis of the processing tool,
When the workpiece and the machining tool are relatively moved, one continuous removal portion by one tool blade in one tooth groove of the workpiece is defined as a unit removal portion,
When the tool reference point is aligned with the axial end face on the machining end side of the gear generating portion of the workpiece, the portion of the unit removed portion located in the tooth space of the workpiece is defined as the actual removed portion. and when defining a portion of the unit removed portion located outside the tooth space of the workpiece as a virtual removed portion,
The tool design department
When the sharpening angle attached to the tool blade is set to an angle different from the helix angle of the tool blade, the length of the actual removed portion (C2) is determined by the sharpening angle applied to the tool blade and the twist angle of the tool blade. Setting the sharpening angle attached to the tool blade with respect to the helix angle of the tool blade so as to be shorter than the actual length (C1) of the removed portion when set to the same angle as the angle, gear machining Device. 2. The gear machining apparatus according to claim 1, wherein said tool designing section sets the rake angle of said tool edge of said machining tool having said negative rake angle to be smaller than said intersection angle. The tool design unit sets the sharpening angle attached to the tool blade of the machining tool having the negative rake angle in a direction in which the blade surface on the machining start side of the left and right blade surfaces of the tool blade becomes an acute angle. By setting the sharpening angle attached to the tool blade, the length (C2) of the actual removed portion when the sharpening angle attached to the tool blade is set to an angle different from the helix angle of the tool blade, and the sharpening angle attached to the tool blade is 3. A gear machining apparatus according to claim 1 or 2, wherein the length (C1) of said actual removed portion is shorter than when the helix angle of said tool blade is set to the same angle. The tool design section sets the rake angle to a positive angle so that the tip angle of the tool blade becomes an acute angle, and sets the sharpening angle attached to the tool blade to the same angle as the helix angle of the tool blade. designing a machining tool with a positive rake angle,
The machining control unit performs rough machining of the workpiece with a machining tool having a positive rake angle, and performs finish machining of the workpiece with a machining tool with a negative rake angle to create the gear. A gear machining apparatus according to any one of claims 1 to 3. A state in which the central axis of a processing tool having a plurality of tool edges on the outer periphery is at an angle (intersecting angle) with respect to an axis parallel to the central axis of the workpiece,
While synchronizing the rotation of the workpiece around the central axis of the workpiece and the rotation of the machining tool around the central axis of the machining tool,
A gear machining method for generating a gear on the workpiece by feeding the machining tool to the workpiece in the central axis direction of the workpiece,
The rake angle of the tool edge of the machining tool is set to a negative angle, and the sharpening angle attached to the tool edge is set to an angle different from the helix angle of the tool edge, so that the rake angle is negative. a tool design process for designing a tool;
a machining control step of machining the workpiece with a machining tool having a negative rake angle to create the gear;
with
In the processing tool, a tool reference point is defined as the intersection of a plane orthogonal to the center axis of the processing tool and including the cutting edges of the plurality of tool blades and the center axis of the processing tool,
When the workpiece and the machining tool are relatively moved, one continuous removal portion by one tool blade in one tooth groove of the workpiece is defined as a unit removal portion,
When the tool reference point is aligned with the axial end face on the machining end side of the gear generating portion of the workpiece, the portion of the unit removed portion located in the tooth space of the workpiece is defined as the actual removed portion. and when defining a portion of the unit removed portion located outside the tooth space of the workpiece as a virtual removed portion,
The tool design process includes:
When the sharpening angle attached to the tool blade is set to an angle different from the helix angle of the tool blade, the length of the actual removed portion (C2) is determined by the sharpening angle applied to the tool blade and the twist angle of the tool blade. Setting the sharpening angle attached to the tool blade with respect to the helix angle of the tool blade so as to be shorter than the actual length (C1) of the removed portion when set to the same angle as the angle, gear machining Method.

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