JP2012101313A - Method for machining tooth surface of spiral bevel gear - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for machining a tooth surface of a spiral bevel gear, easily correcting a tooth trace by only controlling a rotation center position of a cutter, without requiring an expensive device or an advanced technique.SOLUTION: The method includes steps of: installing a gear 4 to be cut so that a center axis thereof passes an origin of coordinates, and that a tooth bottom conical surface is parallel to an X-Y plane; moving the cutter 1 in a Z-axis direction while rotating it, and moving a rotation center axis of a cutting edge 3 along an arc having the origin of coordinates as the center; correcting a trajectory of the rotation center axis of the cutting edge 3 so that the trajectory passes a large diameter-side correction position and a small diameter-side correction position which have been shifted in the X- and Y-axis directions by a large diameter-side correction value and a small diameter-side correction value converted based on correction target values at ends of large- and small-diameter sides of the tooth surface and a correction start position of the tooth surface, from a reference trajectory passing a large diameter-side reference position and a small diameter-side reference position; thereby forming areas which causes no tooth contact under no load at both ends of the tooth trace.

Description

  The present invention relates to a tooth surface processing method for a bent bevel gear.

The tooth surface of the bent bevel gear is formed by performing gear cutting based on the result of an advanced calculation process using an expensive dedicated gear cutter and a dedicated cutter. The subtle modification of the final tooth contact is highly expected from the skills of experienced technicians, and requires high costs, long working time and special skills.
In other words, for gear and pinion tooth surface processing, based on special techniques and experience, and advanced calculations, fine adjustment from the reference coordinate position (fine adjustment by moving the machine table back and forth, fine adjustment by moving the workpiece in the axial direction) It was necessary to perform machine settings by adjusting the offsets that shift the axes, and to determine the tilt and position of the cutter.

More specifically, the tooth surfaces of gears and pinions are usually processed using a “clamp tooth cutting tool” and a “bend bevel gear cutter” shown in JIS B 0174.
The tooth surface of the gear (large gear) is processed by a simple movement of the cutter in which a cutter having a trapezoidal section of cutting teeth is attached to a reference position and the cutter is rotated and fed in the axial direction.
The tooth surface of the pinion (small gear) is processed with a dedicated cutter for processing the pinion tooth surface, but in order to obtain an appropriate tooth contact with the mating gear, processing including tooth contact modification is always performed.
Tooth contact correction method is generally to obtain the target “tooth contact” by processing in the “machine setting adjustment” state in which the mounting position of the cutter and pinion gear is moved from the reference position to a single item or multiple items. However, advanced experience and skills are required to determine machine setting modification specifications.

In addition, in order to obtain sufficient gear strength, life, and vibration reduction, it is necessary to ensure appropriate tooth contact, and as a guideline, the tooth contact of a bent tooth bevel gear is defined in JIS B 1741-1977. . This regulation describes the contact length in the tooth trace direction and the tooth height direction required for each section of the bevel gear, and is approximately 10% of the length of the tooth trace from both ends of the tooth trace. It is stated that there should be no strong hits.
Depending on the purpose, in order to secure the tooth contact at the position intended by the designer, several correction trials may be performed on the tooth profile and the tooth trace, but the prediction calculation requires advanced calculation, experience, and time. It usually costs money.

Conventionally, a disc-shaped cutter whose rotational plane is aligned with the pitch cone angle of the work gear is revolved by attaching the disc-shaped cutter to the tool shaft, attaching the work gear to the main shaft, and moving the tool shaft in three directions. Then, a spiral bevel gear manufacturing method is described in which a virtual crown gear appears (see Patent Document 1).
According to the above-described conventional method, the tooth surface of the bent bevel gear can be processed by a general-purpose machine tool without using a dedicated gear cutting machine for the bent gear. However, this method does not include a technique for correcting the tooth trace of the gear in order to obtain an appropriate tooth contact.

JP 2002-273623 A

  The problem to be solved by the present invention is that it is possible to easily correct tooth traces by simply controlling the rotation center position of the cutter without requiring expensive equipment and advanced technology, and tooth surface processing is easy. An object of the present invention is to provide a method of processing a tooth surface of a bent bevel gear that can be manufactured at low cost.

  According to the method of processing a tooth surface of a bevel gear according to the present invention, a cutter having a cutting edge can be moved in X, Y, and Z axis directions orthogonal to each other, and the rotation center axis of the cutting edge is parallel to the Z axis. The cutting gear is installed so that the central axis thereof passes through the coordinate origin, and the root conical surface of the tooth formed on the cutting gear is parallel to the XY plane. Is moved in the Z-axis direction while rotating the cutter, and the rotation center axis of the cutting blade is moved in the X- and Y-axis directions along an arc centered on the coordinate origin to cut the peripheral surface of the gear to be cut. A method of processing a tooth surface of a bent bevel gear pair, wherein the trajectory of the central axis of rotation of the cutting blade is a large-diameter side reference position and a small-diameter side where the tooth surface of the bent bevel gear pair contacts the entire surface. From the reference trajectory passing through the reference position, the correction target at the large diameter side end and the small diameter side end of the tooth surface And a correction trajectory passing through the large-diameter correction position and the small-diameter correction position moved in the X and Y axis directions by the large-diameter correction value and the small-diameter correction value converted based on the correction start position of the tooth surface, A region where there is no tooth contact at the time of no load is formed at both ends of the tooth trace.

The peripheral surface of the gear to be cut may be cut by rotating the gear to be cut around its central axis so that the cutting edge coincides with the conical surface of the tooth bottom.
A region without the tooth contact at the time of no load can be formed only in the tooth trace of the gear to be cut that is one bent bevel gear.
Cutting is performed with the trajectory of the rotation center axis of the cutting edge as the reference trajectory, and after forming a tooth surface on which the pair of bevel gears are in full contact with the gear to be cut, the trajectory of the rotation center axis of the cutting edge May be cut as a correction trajectory to form areas where there is no tooth contact under no load at both ends of the tooth trace.

Alternatively, cutting may be performed with the trajectory of the rotation center axis of the cutting blade as a correction trajectory, and a tooth surface having areas where there is no tooth contact at no load at both ends of the tooth trace may be created.
Using a cutter having a cutting edge with a trapezoidal cross section and moving the cutter in the Z-axis direction until the tip of the cutting edge reaches the root conical surface, the area where there is no tooth contact at all loads over the entire tooth height May form.
In addition, by using a cutter having a cutting edge with a cutting part formed at the tip of the side surface, and controlling the movement of the cutter in the Z-axis direction, a region where there is no tooth contact when no load is applied to a part of the tooth height May be formed.

According to the first aspect of the present invention, tooth surface creation and tooth traces can be easily performed without controlling an expensive gear-cutting machine or advanced technology for tooth surface processing only by controlling the rotation center position of the cutter. Since correction can be performed, tooth surface processing is easy, and the cost required for tooth surface processing is low.
According to the invention which concerns on Claim 2, a tooth surface can be formed so that a tooth root may contact | abut with a conical surface of a tooth bottom correctly also in the large diameter side edge part and small diameter side edge part of a tooth trace.
According to the third aspect of the present invention, the tooth to be cut that is the other bevel gear bend gear is not subjected to tooth trace correction, and only by cutting with the rotation center axis of the cutting blade set as the reference position, the desired tooth is obtained. Wins can be secured.

It is a side view which shows the cutter and the to-be-cut gear according to the Example of this invention. It is a side view which shows the bending bevel gear pair which concerns on the Example of this invention. It is a top view which shows the cutting blade position at the time of a process of an average cone distance position, and a to-be-cut gear. It is a top view which shows the cutting blade position at the time of a process of a large diameter side edge part, and a to-be-cut gear. It is a top view which shows the cutting blade position at the time of a process of a small diameter side edge part, and a to-be-cut gear. It is a figure which shows the track | orbit of a cutter circular arc center at the time of tooth surface processing. (A) is a tooth surface having a square tooth contact shape, (b) is a tooth surface having an oval tooth contact shape, and (c) is elliptical and inclined. It is a figure which shows the tooth surface which has a tooth aiming shape. It is a figure which shows the relationship between the center movement of a cutter circular arc at the time of performing a tooth trace correction in a large diameter side edge part, and an original circle and a correction arc. It is a principal part enlarged view of FIG. It is a reference diagram for explaining a first method for obtaining the center movement amount of the cutter arc. It is a reference diagram for explaining a second method for obtaining the center movement amount of the cutter arc. It is sectional drawing of the cutter which has a cross-section trapezoidal cutting blade. It is a figure which shows the track | orbit of a cutter circular arc center in the case of adding correction to both ends of a tooth trace. It is a figure which shows the tooth trace which added the correction to both ends. It is sectional drawing of a point cutter.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
As shown in FIG. 1, using a cutter 1 having a plurality of cutting blades 3 disposed on the outer periphery of a disk 2, a bevel gear bevel gear pair (a gear G1 and a tooth having a large number of teeth) as shown in FIG. The tooth surface processing of a small number of pinions G2) is performed.
The cutter 1 is movable in the X, Y, and Z axis directions orthogonal to each other, and is attached to the tip of a tool axis (not shown) parallel to the Z axis.
The gear 4 to be cut is attached to the tip of the rotary shaft 5 that is included in the XZ plane through the coordinate origin (O1) and arranged on the A axis whose angle with the X axis is variable. The gear 4 to be cut has a central axis coinciding with the A axis, and a conical surface including the root of each tooth to be formed on the circumferential surface is parallel to the XY plane, that is, with the A axis. The intersection angle with the X axis is set to be the same as the root cone angle.
And the tooth surface of the gear G1 and the pinion G2 is obtained by moving in the Z-axis direction while rotating the tool shaft and driving the cutter 1 until the tip of the cutting edge 3 reaches the bottom cone surface.

When actually performing tooth surface processing, the basic design of the gear G1 and the pinion G2 is given as a drawing.
The cross-sectional shape of the cutting blade 3 of the cutter 1 and the radius of the disk 2 (the radius of the track of the cutting blade 3) for processing the tooth surface of the gear G1 are determined. The radius of the orbit of the cutting edge 3 is set to be the same as or slightly smaller than the large-diameter conical distance (distance from the coordinate origin to the large-diameter side end of the gear 4 to be cut) of the gear 4 to be cut.
Using the tooth surface of the gear G1 obtained by machining with the cutter 1 as a group of points on the three-dimensional tooth surface, the coordinates, normal vector, and radius of curvature of each point are obtained.
Next, a “conjugate tooth surface” of the pinion G2 meshing with the gear G1 is obtained by a mathematical method. The “conjugate tooth surface” obtained by calculation is naturally 100% per tooth surface when the gear G1 and the pinion G2 are engaged with each other.
In order to put this curved bevel gear pair into practical use, appropriate modification is made to the tooth surface of one bent bevel gear (usually pinion G2 having a small number of teeth), and the above-mentioned JIS standard (or US AGMA standard). The tooth contact conforming to 390.03) must be ensured.

In order to machine the gear 4 to be cut with the cutter 1, as shown in FIG. 1, the cone apex of the gear 4 to be cut coincides with the coordinate origin (O1), and the root cone surface is parallel to the XY plane. Thus, the rotation surface of the cutting blade 3 of the cutter 1 is set to be parallel to the XY plane.
As shown in FIG. 3, the position at the mean cone distance “md” of the gear 4 to be cut on the X axis is “D”, and the radius of the cutter arc S, which is the center trajectory of the cutting edge 3, is set. Let it be “rc”.
At the point D, the center of the cutter arc S (the rotation center axis of the cutting blade 3) O2D (X = H0, Y = V0) is determined so that the intersection angle between the cutter arc S and the X axis becomes a predetermined twist angle β. The length of the arm in the polar coordinate display of the center O2D is L, and the angle between the arm and the Y axis is Θ.

FIG. 3 shows the shape of the tooth bottom when the cutter 1 is rotated and the gear 4 to be cut is machined in this state. As is apparent from FIG. 3, at the point D, the track of the center tip of the cutting blade 3 coincides with the bottom cone surface of the gear 4 to be cut, but at the small diameter end B and large diameter end C of the tooth bottom. Detach from the root conical surface.
In order for the cutting edge 3 to be on the tooth bottom conical surface of the gear 4 to be cut at the large-diameter end C, as shown in FIG. 4, the tool axis is controlled so that the center of the cutter arc S is “02C” [ X = (H) FOR 02C, Y = (V) FOR 02C] and the gear 4 to be cut is moved to the A axis until the straight line connecting the large diameter side end C and the coordinate origin is parallel to the X axis. Need to rotate around.
When the center “02C” of the cutter arc S at this time is indicated by polar coordinates, the arm length L does not change and the angle Θ = (Θ) FOR 02C between the arm and the Y axis is obtained.

Further, in order for the cutting edge 3 to be on the tooth bottom conical surface of the gear 4 to be cut at the small-diameter side end B, the center of the cutter arc S is set to “02B” [X = (H) as shown in FIG. FOR 02B, Y = (V) FOR 02B], and the gear 4 to be cut is reversely rotated about the A axis until the straight line connecting the large diameter side end B and the coordinate origin is parallel to the X axis. There is a need.
When the center “02B” of the cutter arc S at this time is indicated by polar coordinates, the arm length L does not change and the angle Θ = (Θ) FOR 02B between the arm and the Y axis is obtained.
In actual machining, the rotation angle of the gear 4 to be cut is set larger than the range shown in FIGS.
As shown in FIG. 6, the center of the cutter arc S moves on one arc of radius L, and the root center line formed on the gear 4 to be cut passes through B, D, and C.
In this way, by continuously controlling the rotation angle of the gear 4 to be cut and “Θ”, the tooth bottom can be correctly machined on the conical surface of the tooth bottom of the gear 4 to be cut and the tooth profile is created. To do.

By the way, as described above, one bent tooth bevel gear must be corrected to have a proper tooth contact. For this purpose, the portion of the conjugate tooth surface of the pinion G2 excluding the target contact shape at the time of no load is released to eliminate the tooth contact at the time of meshing at the time of engagement.
FIG. 7 shows a tooth contact aiming area b when no load is applied on the tooth surface a. 7A is a square tooth contact area b, FIG. 7B is an oval tooth contact area b, and FIG. 7C is an oval and inclined tooth contact area. Each target area b is shown.

When correcting the tooth trace at the large-diameter end of the tooth surface, a correction start point E of the tooth trace is determined, a correction target value δ at the large-diameter end C is given, and the teeth between “E-C” The muscle is corrected to obtain a corrected tooth muscle “B-D-E-C ′”. The correction target value δ and the correction start point E of the tooth trace are determined in consideration of the deformation amount of the tooth surface a at the time of loading, the target tooth contact aiming area b, and the like.
Thus, in order to start the correction from the point E and obtain the correction target value δ at the large-diameter end C, the center of the cutter arc is increased from the large-diameter reference position “02C” as shown in FIG. Move to the radial side correction position “02C ′”.
When the large diameter side correction position “02C ′” is indicated by X and Y coordinates,
X (02C ′) = X (02C) + ΔX
Y (02C ′) = Y (02C) + ΔY.
From the position of the correction start point E and the correction target value δ at the large-diameter end C, the large-diameter correction value (ΔX, ΔY) at the center of the cutter arc S can be easily obtained.

The center of the cutter arc S is moved from the large-diameter side reference position “02C” to the large-diameter side correction position “02C ′”, and as shown in FIG. 9, the cutting blade 3 passes through “B-D-C”. By intersecting the cutter arc (original arc) S at point E and rotating along a modified arc S ′ having a radius rc passing through “BD-C-C ′”, the large-diameter side end of the concave tooth surface The target tooth muscle correction can be performed on the part.
When the tooth trace on the large diameter side is corrected by this method, the point B moves to B ″ and the point D moves to D ″ on the correction arc S ′, but the tooth is between (B ″ −E). Since there is no surface, it is not cut.
Further, different correction curves can be obtained depending on the path for moving the center of the cutter arc S from the large-diameter side reference position “02C” to the large-diameter side correction position “02C ′”. In order to achieve this, the center of the cutter arc S is gently moved from “02C” to “02C ′”.

Hereinafter, a method for obtaining the movement amount of the center of the cutter arc S based on the correction target value δ and the position of the correction start point E will be specifically described.
As shown in FIG. 10, the point E is a point common to the original arc S and the corrected arc S ′, and the point C ′ is a point on the straight line L1 passing through the large-diameter side reference position “02C” and the point C. C to δ.
When a circle S1 having a radius rc centered on the point E and a circle S2 having a radius rc centered on the point C ′ are defined, the large-diameter side reference position “02C” is on the circle S1.

When the intersection of the circle S1 and the circle S2 is (02C ′), this point is the center of the corrected arc S ′ obtained. That is, since the point (02C) and the point (02C ′) are both at the equidistant position rc from the point E, the point (02C ′) is the center of the corrected arc S ′ obtained.
Although the circle S1 and the circle S2 have two intersections, other intersections that are not the point (02C ′) shown in the figure can be ignored because the movement distance of the cutter 1 becomes large and is not realistic.
The values of ΔX and ΔY, which are the movement amounts of the center of the cutter arc S, can be obtained by formulating the above method or obtained on CAD.

As specific numerical values, the large diameter cone distance of the gear 4 to be cut is 53.93 mm, whereas rc = 50.8 mm, X (02C) = 20.9218 mm, Y (02C) = 38. If 6148 mm, δ = 0.071 mm, and the distance E value between (E−C) = 5.4 mm, ΔX = 0.552 mm and ΔY = 0.347 mm.
If the correction target value δ is set to “−”, the tooth trace correction can be performed on the convex tooth surface by the same method.

Also, the amount of movement of the center of the cutter arc S can be easily obtained by the following method.
As shown in FIG. 11, the point C ′ and the point E are connected by a straight line L2, and an equation of the straight line L2 is obtained. The midpoint between the point C ′ and the point E is G, and an equation of a straight line L3 passing through the point G and orthogonal to the straight line L2 is obtained.
When the intersection point between the straight line L3 and the circle S1 is obtained, this point (02C ′) coincides with the intersection point between the straight line L3 and the circle S2, so that the obtained point (02C ′) is the center of the corrected arc S ′.
That is, the amount of movement of the rotation center of the cutting blade 3 can be uniquely determined with respect to the correction target value δ and the position of the correction start point E.

Next, the case where correction processing is performed on the large-diameter side end portion C and the small-diameter side end portion B of the concave tooth surface after the tooth surface is formed will be described.
As in the specific example described above, rc = 50.8 mm, X (02C) = 20.9218 mm, and Y (02C) = 38.6148 mm.
The cutter 1 has a cutting blade 3 having a trapezoidal cross section as shown in FIG. 12, and performs tooth surface formation and correction processing in a state where the cutting blade 3 is driven to the tooth bottom. The side surface on the cutter outer periphery side of the cutting edge 3 processes the concave tooth surface, and the side surface on the cutter center side processes the convex tooth surface.
First, the cutter 1 is reciprocatingly rotated so that the center of the cutter arc S passes through the reference trajectory (02B, 02D, 02C), and the uneven tooth surface is roughly processed leaving a finishing allowance on the uneven tooth surface. In practice, roughing is performed by cutting with a cutting blade that is as thin as the finishing allowance.

Then, after processing the concave tooth surface without correction of the tooth trace, the tooth trace correction is performed on the large-diameter side end portion C of the concave tooth face.
In order to make the distance between (E-C) 10.4 mm and to correct δ = 100 μ at the large-diameter end C, the center of the cutter arc S is set to the large-diameter reference position as shown in FIG. It moves from “02C” to the large diameter correction position “02C ′” corrected by the large diameter correction value (ΔXC = 421 μ, ΔYC = 226 μ).

Further, the tooth trace is corrected from the small diameter side end B of the concave tooth surface to the correction start point F. When the distance between (B-F) is 10.4 mm, the center of the cutter arc S is corrected from the small-diameter side reference position “02B” by the small-diameter correction value (ΔXB = −386 μ, ΔYB = −353 μ). By moving to the position “02B ′”, a tooth trace having a correction amount of 0 at point F and a correction amount of 100 μ at point B can be processed.
That is, only by slightly moving the center of the cutter arc S from the reference trajectory (02B → 02D → 02C) to the corrected trajectory (02B ′ → 02D → 02C ′), as shown in FIG. -E-C '"can be finished into a tooth trace shape.

At this time, if the cutting edge 3 having a trapezoidal cross section is used and the cutter 1 is moved in the Z-axis direction until the tip of the cutting edge 3 reaches the bottom conical surface, the tooth trace is corrected. It is corrected over the tooth height. Accordingly, the tooth contact shape is a quadrangle.
When the correction start points E and F are made coincident with the point D, a tooth muscle subjected to full crowning correction is obtained.
In addition, it is possible to correct the tooth traces of the rough tooth surfaces after forming a convex tooth surface with no tooth trace correction by the same method.

It is also possible to correct tooth traces simultaneously with the creation of the tooth surface.
For example, when forming the concave tooth surface, the cutter 1 is moved in the Z-axis direction and reciprocally rotated while controlling the center of the cutter arc S to pass through the correction trajectory (02B ′ → 02D → 02C ′) from the beginning. Thus, a concave tooth surface having a tooth trace shape of “B′-FDEC ′” can be created.
When a concave tooth surface is formed, a convex tooth surface is automatically formed. However, since the thickness of the cutting blade 3 is thinner than the width of the tooth gap, this convex tooth surface is not a correct tooth surface. That is, since the finishing allowance remains on the convex tooth surface and the tooth thickness is thicker than the target value, the normal convex tooth surface is formed by moving the cutter 1 to the convex tooth surface side and cutting. To do. At this time, the tooth trace can be corrected simultaneously with the creation of the convex tooth surface.

As shown in FIG. 15, when a point-type cutter 1 ′ having a cutting edge 3 ′ having a cutting portion 3 a formed at the side end portion is used, only a portion in contact with the cutting portion 3 a is cut. The movement of 1 in the Z-axis direction can be controlled, and a region where there is no tooth contact at the time of no load can be formed in a part of the tooth height.
Therefore, if the point-type cutter 1 ′ is used, it is possible to modify the tooth surface obliquely or to form an oval tooth contact.
Using a cutter having a cutting edge for roughing with a trapezoidal cross section, it is possible to perform roughing with a finishing allowance remaining on the tooth surface, and then finish with a point-type cutter 1 ′.

The pinion G2 may be a conjugate tooth surface and the tooth trace correction may be performed on the gear G1 having a large number of teeth.
Unlike the processing for the small-diameter pinion G2, the gear G1 has a large number of teeth and a large diameter. Therefore, it is not necessary to rotate around the A axis (center axis) when performing tooth surface processing. However, even though the diameter is large, if the tooth surface is formed without rotating the gear G1, the tooth bottom is slightly separated from the root conical surface at the small diameter side end B and the large diameter side end C of the tooth trace. End up. Accordingly, there is a case where the tooth surface processing is performed while the gear G1 is slightly rotated around the central axis in order to make the tooth bottom accurately coincide with the tooth bottom conical surface.
Further, when correcting the tooth trace of the gear G1, the number of teeth to be corrected is larger than the correction of the pinion G2, but the amount of movement of the center of the cutter arc S is small.
In the above description, the large-diameter side correction value and the small-diameter side correction value are indicated by the X and Y coordinates. However, in the polar coordinates, the angle Θ between the arm and the Y axis is not changed, and the correction value of the arm length L is changed. It can also be obtained as ΔL.

1, 1 'Cutter 2 Disc 3, 3' Cutting edge 3a Cutting part 4 Gear to be cut 5 Rotating shaft a Tooth surface b Tooth contact area G1 Gear G2 Pinion

Claims (7)

  A cutter having a cutting edge is provided so as to be movable in the X, Y, and Z axis directions orthogonal to each other, and the rotation center axis of the cutting edge is parallel to the Z axis. It is arranged so that it passes through the origin of coordinates and the root conical surface of the tooth formed on the gear to be cut is parallel to the XY plane, and moves in the Z-axis direction while rotating the cutter. In this method, the peripheral surface of the gear to be cut is cut by moving the rotation center axis of the blade in the X and Y axis directions along an arc centered on the coordinate origin to process the tooth surface of the bevel gear pair. From the reference trajectory passing through the large-diameter side reference position and the small-diameter side reference position where the tooth surfaces of the pair of bent bevel gears are in full contact with each other, Conversion based on the correction target value at the end and the small diameter end and the correction start position of the tooth surface By making the correction trajectory through the large diameter side correction position and the small diameter side correction position moved in the X and Y axis directions by the large diameter side correction value and the small diameter side correction value, the tooth contact at both ends of the tooth trace is applied at no load. A tooth surface processing method for a bent bevel gear, characterized by forming a non-existing region.   The tooth of the bent bevel gear according to claim 1, wherein the peripheral surface of the gear to be cut is cut by rotating the gear to be cut around its central axis so that the cutting edge coincides with the conical surface of the tooth bottom. Surface processing method.   The tooth surface processing method for a curved bevel gear according to claim 1 or 2, wherein a region without the tooth contact at the time of no load is formed only in a tooth trace of the gear to be cut which is one bent bevel gear.   Cutting is performed with the trajectory of the rotation center axis of the cutting edge as the reference trajectory, and after forming a tooth surface on which the pair of bevel gears are in full contact with the gear to be cut, the trajectory of the rotation center axis of the cutting edge The tooth surface processing method of the curved bevel gear according to any one of claims 1 to 3, wherein cutting is performed with the correction track as a correction trajectory, and regions where there is no tooth contact under no load are formed at both ends of the tooth trace.   The cutting surface is cut using the trajectory of the rotation center axis of the cutting edge as a correction trajectory, and a tooth surface having a non-loading region at both ends of the tooth trace is created. A tooth surface processing method for a curved bevel gear.   Using a cutter having a cutting edge with a trapezoidal cross section and moving the cutter in the Z-axis direction until the tip of the cutting edge reaches the root conical surface, the area where there is no tooth contact at all loads over the entire tooth height The tooth surface processing method of the curved bevel gear according to any one of claims 1 to 5.   Using a cutter having a cutting edge with a cutting portion formed at the tip of the side, and controlling the movement of the cutter in the Z-axis direction, a region where there is no tooth contact at no load is formed in part of the tooth height The tooth surface processing method of the curved bevel gear according to any one of claims 1 to 5.

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