JP4310778B2 - Broach for helical internal gear machining - Google Patents

Description

          The present invention relates to a broach used for cutting a helical internal gear.

As a broach generally used for cutting helical internal gears, as shown in the elevational front view of FIG. 2, the main body 10 has a front handle 1 that pulls the broach toward a rear handle 2 that is a rear support portion. A rough blade portion 3 that performs cutting in the outer diameter direction that increases the blade height, and a finishing portion 4 that performs cutting in the tooth thickness direction following the rough blade portion 3 are provided, and a finishing round blade 5 that sometimes cuts the gear small diameter portion is provided. It may be provided. The rough blade portion 3, the finishing portion 4 and the finishing round blade 5 may be manufactured as a single unit, or may be manufactured as an assembly type with the finishing portion 4 as a shell.
As shown in FIG. 3, which is an enlarged view of the finish 4 of FIG. 2 formed as a shell, a large number of cutting edges 6, 6 a are cut along the spline helix angle β with respect to the axis XX along the outer diameter direction. The finish portion 4 is formed as a rough blade portion 3 as a blade and a tooth thickness direction cutting blade.
In Patent Document 1, a broach for helical internal gear machining in which the spline twist angle β of the finish 4 as the tooth thickness direction cutting blade is 19 ° <β ≦ 34 °, and the blade groove twist angle α and the spline twist angle β And a plurality of cutting edges in the longitudinal direction are formed, and the cutting edge angle δ _R of the obtuse flank is determined by limiting the blade groove torsion angle α to a range of 0 ° <α <38 ° −β. 90 ° + (β−19 °) × 2 <δ _R <90 ° + β
By setting the spline torsion angle β and blade groove torsion angle α appropriately, the rotational force generated on the work piece and broach cutting edge can be suppressed, and high-precision gears can be processed. A broach for machining helical internal gears is disclosed.
Japanese Patent Publication No. 8-18181 Claims 1 and 3

In a conventional broach for helical gear cutting as shown in Patent Document 1, each broach cutting edge cuts a work piece with an acute flank (left as viewed in FIG. 1) in front of the finish 4, and an obtuse angle behind the finish 4. Since many methods of cutting the workpiece with flank (right in FIG. 1) were adopted, the gear precision could be greatly improved by stabilizing the cutting force of the obtuse flank rear cutting blade. Further, the method of cutting the acute angle flank and the obtuse angle flank separately is an effective means for preventing chip clogging due to interference when chips are generated from the left and right at the same time.
However, the method of finishing the acute flank in front of finish 4 and the obtuse flank in the back of finish 4 sometimes causes the right flank and left flank tooth trace error tendency values to differ by 0.005 or more due to the time lag of cutting. To do. This is thought to be due to the reduction in rigidity due to the reduction in the thickness of the internal gears as the automobiles have recently become lighter.

  The problem of the present invention is that, in the conventional broach for helical gear processing shown in Patent Document 1, a right flank is created by a time lag of cutting by a method of finishing an acute flank in front of the finish and an obtuse flank in the rear of the finish. It is an object of the present invention to provide a helical internal gear machining broach capable of machining a gear with higher accuracy and preventing the left flank tooth trace error tendency value from differing by 0.005 or more.

Therefore, the present invention is a broach for helical internal gear machining in which the spline twist angle β is 19 ° <β ≦ 34 °, and the blade groove twist angle α and the spline twist angle β intersect with each other in the longitudinal direction. By forming the cutting edge and limiting the groove groove torsion angle α to the range of 0 ° <α <38 ° −β, each cutting edge angle δ _R of the obtuse flank is 90 ° + (β−19 °) × 2 <δ _R <90 ° + β
In the helical internal gear machining broach set in the range of
Set the acute angle flank cutting amount Δt _L to 0.001 to 0.003 mm,
The cutting amount Δt _R of the obtuse flank is set to 0.004 to 0.008 mm,
And the clearance angle γ _L of the cutting blade and the acute flank with a Δt _R / Δt _L ratio of 2.5 or more is set to 0 ° 10 ′ to 0 ° 20 ′,
The above-described problem of the present invention is achieved by a helical internal gear machining broach characterized by having a cutting edge having a relief angle γ _R of an obtuse flank γ _L + (0 ° 10 'to 0 ° 20') and a large setting blade. Settled.

Conventionally, there is a broach that cuts acute flank and obtuse flank at the same time, but the sharp flank cutting amount Δt _L and obtuse flank cutting amount Δt _R are the same, or the acute flank clearance angle γ _L and obtuse angle Many cutting patterns have been tried for the flank clearance angle γ _R , but the gear accuracy has not been improved decisively.
In the present invention, the spline twist angle β is 19 ° <β ≦ 34 °, the blade groove twist angle α is limited to the range of 0 ° <α <38 ° −β, and each cutting edge angle δ _R of the obtuse flank is 90 °. + (Β−19 °) × 2 <δ _R <90 ° + β
In addition, the cutting amount Δt _L of the acute flank is set to 0.001 to 0.003 mm,
The cutting amount Δt _R of the obtuse flank is set to 0.004 to 0.008 mm,
And the clearance angle γ _L of the cutting blade and the acute flank with a Δt _R / Δt _L ratio of 2.5 or more is set to 0 ° 10 ′ to 0 ° 20 ′,
Because it is a broach for helical internal gear machining, characterized by having a cutting edge with a relief angle γ _R of the obtuse flank γ _L + (0 ° 10 'to 0 ° 20') set large, Cutting of sharp flank and obtuse flank at the back of the finish cuts the time lag of cutting to prevent the gear error tendency value of the right flank and left flank from differing by more than 0.005 and to process a higher precision gear. It has become possible to provide a broach for processing helical internal gears.

The helical internal gear machining broach according to the present invention is a so-called off-normal blade groove, but cannot be applied to a different so-called axial right angle groove (α = 0) or tooth right angle groove (β = α). The heel experiment was conducted, and it was confirmed that the tooth trace error worsened with the tooth right angle groove and improved with the right angle blade groove, which is commonly called a dog leg. Because there is a difference from the processing of precision gears, it is limited to so-called off-normal blade grooves.
Preferably, the cutting amount Δt _L of the acute flank of one rear final finishing blade of the broach or two rear final finishing blades of the broach,
When the last cutting edge passes through the work piece by setting it to -0.001 to -0.003 mm, the number of simultaneous cutting edges at the time of forward cutting [the work length (tooth The number of cutting blades involved in cutting in the width) is always 1 when the final pull-out occurs, so that it is possible to prevent wobbling of the rear finishing blade of the rear part of the broach due to the change in cutting load. It is now possible to provide a broach for helical internal gear machining that makes it possible.
More preferably, by cutting the acute flank and the obtuse flank at the same time, the cutting amount Δt _L of the acute flank can be dispersed, so that the cutting amount is reduced overall, wear is reduced, and the life is improved. Further, efficient cutting reduces the length of the blade and enables supply of an inexpensive broach.

A best mode for carrying out the present invention will be described with reference to FIG. FIG. 1 is an enlarged plan view showing a cutting state of one blade of a finishing section 4 that performs cutting in the tooth thickness direction of a broach generally used for cutting a helical internal gear shown in FIG. The helical internal gear machining broach of the present invention is a helical internal gear machining broach having a spline torsion angle β of 19 ° <β ≦ 34 °, wherein the blade groove torsion angle α and the spline torsion angle β intersect each other. By forming a large number of cutting edges in the longitudinal direction and limiting the groove twist angle α to the range of 0 ° <α <38 ° −β, each cutting edge angle δ _R of the obtuse flank is 90 ° + (β −19 °) × 2 <δ _R <90 ° + β
In the helical internal gear machining broach set in the range of
The cutting amount Δt _L of the acute angle flank 12 is set to 0.001 to 0.003 mm,
The cutting amount Δt _R of the obtuse flank 11 is set to 0.004 to 0.008 mm,
And the clearance angle γ _L of the cutting blade and the acute flank with a Δt _R / Δt _L ratio of 2.5 or more is set to 0 ° 10 ′ to 0 ° 20 ′,
A helical internal gear machining broach characterized by having a cutting edge in which the relief angle γ _R of the obtuse flank is set to γ _L + (0 ° 10 'to 0 ° 20'). F1 _L is the main component of the acute flank, F1 _R is the main component of the obtuse flank, F2 _L is the back component of the acute flank, F2 _R is the back component of the obtuse flank, F3 _L is the resultant force of the acute flank, F2 _R is the combined force of obtuse flank.

FIG. 1 shows a state where a gear having a spline right helix angle β is cut in the tooth thickness direction. By setting the left helix angle α in the blade groove, the cutting edge angle δ _R of the obtuse flank 11 (right) becomes δ _R = 90 ° + (β−α).
Considering only the cutting on the obtuse angle flank 11 side, the working angle θ of the cutting edge of the obtuse angle flank 11 (right) acts in the minus direction, that is, the direction of escaping the work piece (see Patent Document 1).
In order to obtain a more accurate gear stably, not only cutting with an acute flank in front of the finish and cutting with an obtuse flank at the rear as in the past, but also with an acute flank simultaneously with the obtuse flank cutting at the rear. It has been found that a gear with less tooth trace error can be obtained with higher accuracy by cutting. In FIG. 1, the working angle θ of the cutting edge of the obtuse flank 11 (right) generated by cutting only the obtuse flank is acting in the minus direction. If the sharp flank 12 is simultaneously cut at this time, the back flank force F2 _L of the acute flank of FIG. 1 is generated, and the working angle θ of the obtuse flank may change from the minus direction region to the plus direction region. Can be easily assumed. The present invention sets the condition for maintaining the working angle θ of the obtuse flank in the minus direction region even under the condition of cutting with the acute flank simultaneously with the obtuse flank cutting to improve the gear accuracy.

Back component force F2 _R of the back component force F2 _L and obtuse flank 11 of acute flank 12 of the cutting in FIG 1 may vary depending cutting angle [delta] _R of the cutting edge angle [delta] _L and obtuse flank 11 of acute flank 12, In the case of a commonly used automobile gear material, it has been confirmed in experiments that the cutting amount is the same as F2 _R / F2 _L = 2.5 to 3.5 times (obtuse flank back force) F2 _R is overwhelmingly large). It is also confirmed that the cutting amount Δt _R of the obtuse flank 11 does not easily cut into the work due to a phenomenon called “slip” even if a minute cut of 0.001 to less than 0.003 mm is given. Has been. On the other hand, the acute flank 12 can perform cutting sensitive to the cutting amount Δt _L of the acute flank.
As a result,
(B) The cutting amount Δt _R of the obtuse flank is set to 0.004 to 0.008 mm, the cutting amount Δt _L of the acute flank is set to 0.001 to 0.003 mm, and the ratio Δt _R / Δt _L is 1. 5 or more
That is, by making the cutting amount Δt _L of the acute flank less than 1 / 2.5 of the cutting amount Δt _R of the obtuse flank, the acute flank can perform cutting sensitive to the cutting amount Δt _L of the acute flank, and the obtuse flank cutting The amount Δt _R does not cause “slip” due to minute cutting, and the back component force of the cutting of the acute flank does not move the working angle θ of the obtuse flank to the negative direction region, thereby improving the gear accuracy. It became.

Looking further the relationship between the back component force F2 _L of the cutting clearance angle gamma _L and acute flank of acute flank 12 of the cutting in FIG 1, increasing the relief angle gamma _L acute flank, back portion of the cutting of acute flank The force F2 _L also increases slightly, so I want to make it as small as possible. This is also advantageous for tooth thickness minus life due to re-polishing. However, decreasing the relief angle gamma _R acute flank clearance angle gamma _L and obtuse flank 11, finish because the surface roughness is decreased, the back component force of the cutting of acute flank while keeping a surface finish roughness of acute flank F2 _L The limit of reducing
(B) A good result is obtained when the clearance angle γ _{L of the} acute flank is 0 ° 10 ′ to 0 ° 20 ′, and the clearance angle γ _R of the obtuse flank is +0 from the clearance angle γ _L of the acute flank It is necessary to increase the angle by 10 ° to + 0 ° 20 ′ in order to maintain the finished surface roughness of the obtuse flank.

If the simultaneous cutting blades of the acute flank and the obtuse flank satisfying the above conditions (a) and (b) are applied to all the blades of the finishing part 4 that performs cutting in the tooth thickness direction, the sharp flank may not be cut by a predetermined amount. Therefore, it is economical to provide cutting blades that satisfy both the conditions (A) and (B) on at least three of the six finishing blades on the rear end of the broach.
When the cutting edge at the end of the broach passes through the work piece, the number of simultaneous cutting edges during cutting forward (the number of cutting edges involved in cutting within the work length (tooth width)) is finally removed. There will always be one. Along with this, a change that the cutting load is reduced occurs. At this time, the obtuse flank does not cut easily as in the case of micro-cutting, and the acute flank reacts sensitively as described above. As a solution to this, by setting the cutting amount Δt _L of the acute angle flank of one rear final finishing blade or two rear final finishing blades of the broach to −0.001 to −0.003 mm, it is based on It has become possible to provide a helical internal gear machining broach that can prevent wobbling of the rear finishing blade of the rear part of the broach and that can process a high-precision gear.

More preferably, by cutting the acute flank and the obtuse flank at the same time, the cutting amount Δt _L of the acute flank can be dispersed, so that the cutting amount is reduced overall, wear is reduced, and the life is improved. Further, efficient cutting reduces the length of the blade and enables supply of an inexpensive broach.
Since this cutting method generates chips from both the left and right flank, the thickness of the broach narrows in the spline large diameter area, so there was concern that both chips would interfere and generate chip clogging. However, there is a large difference between the cutting amount Δt _L of the acute flank and the cutting amount Δt _R of the obtuse flank, the cutting edge angle δ _L of the acute flank, and the cutting edge angle δ _{R of the} obtuse flank. Due to the difference in the curl shape of the cutting, it was confirmed that it was discharged smoothly without interference.
[Effect of Best Embodiment of the Present Invention]

Conventionally, there is a broach that cuts acute flank and obtuse flank at the same time, but the sharp flank cutting amount Δt _L and obtuse flank cutting amount Δt _R are the same, or the acute flank clearance angle γ _L and obtuse angle Many cutting patterns have been tried for the flank clearance angle γ _R , but the gear accuracy has not been improved decisively. In the present invention, the spline twist angle β is 19 ° <β ≦ 34 °, the blade groove twist angle α is limited to the range of 0 ° <α <38 ° −β, and each cutting edge angle δ _R of the obtuse flank is 90 °. + (Β−19 °) × 2 <δ _R <90 ° + β
In addition, the cutting amount Δt _L of the acute flank is set to 0.001 to 0.003 mm,
The cutting amount Δt _R of the obtuse flank is set to 0.004 to 0.008 mm,
And the clearance angle γ _L of the cutting blade and the acute flank with a Δt _R / Δt _L ratio of 2.5 or more is set to 0 ° 10 ′ to 0 ° 20 ′,
Because it is a broach for helical internal gear machining, characterized by having a cutting edge with a relief angle γ _R of the obtuse flank γ _L + (0 ° 10 'to 0 ° 20') set large, Cutting of sharp flank and obtuse flank at the back of the finish cuts the time lag of cutting to prevent the gear error tendency value of the right flank and left flank from differing by more than 0.005 and to process a higher precision gear. It has become possible to provide a broach for processing helical internal gears.

Preferably, the cutting amount Δt _L of the acute flank of one rear final finishing blade of the broach or two rear final finishing blades of the broach,
When the last cutting edge passes through the work piece by setting it to -0.001 to -0.003 mm, the number of simultaneous cutting edges at the time of forward cutting [the work length (tooth The number of cutting blades involved in cutting in the width) is always 1 when the final pull-out occurs, so that it is possible to prevent wobbling of the rear finishing blade of the rear part of the broach due to the change in cutting load. It is now possible to provide a broach for helical internal gear machining that makes it possible.
More preferably, by cutting the acute flank and the obtuse flank at the same time, the cutting amount Δt _L of the acute flank can be dispersed, so that the cutting amount is reduced overall, wear is reduced, and the life is improved. Further, efficient cutting reduces the length of the blade and enables supply of an inexpensive broach.

1 shows a helical internal gear machining broach according to the best mode for carrying out the present invention. The elevation front view of the broach generally used for helical internal gear cutting. Enlarged view of the finish 4 of FIG. 2 formed of a shell

4: Finish 11: Obtuse flank 12: Acute flank (left)
α: Flute helix angle β: Prine helix angle Δt _L : Cutting amount of acute flank Δt _R : Cutting amount of obtuse flank γ _L : Relief angle of acute flank γ _R : Relief angle of obtuse flank δ _L : Cutting sharp flank Cutting angle δ _R : Cutting edge angle of obtuse flank θ: Working angle of cutting edge of obtuse flank

Claims (3)

A helical internal gear machining broach with a spline twist angle β of 19 ° <β ≦ 34 °, and the blade groove twist angle α and the spline twist angle β intersect to form a number of cutting blades in the longitudinal direction. By limiting the groove groove twist angle α to the range of 0 ° <α <38 ° −β, each cutting blade angle δ _R of the obtuse flank is 90 ° + (β−19 °) × 2 <δ _R <90. ° + β
In the helical internal gear machining broach set in the range of
Set the acute angle flank cutting amount Δt _L to 0.001 to 0.003 mm,
The cutting amount Δt _R of the obtuse flank is set to 0.004 to 0.008 mm,
And the cutting edge having a Δt _R / Δt _L ratio of 2.5 or more and the clearance angle γ _L of the acute flank is set to 0 ° 10 ′ to 0 ° 20 ′,
Three or more of the six finishing blades on the rear finishing blade side of the broach with a cutting blade that has both a cutting blade with a relief angle γ _R of obtuse flank set to γ _L + (0 ° 10 'to 0 ° 20'). A broach for processing a helical internal gear. A cutting amount Δt _L of the acute angle flank of one rear final finishing blade of the broach or two rear final finishing blades of the broach,
The helical internal gear machining broach according to claim 1 , characterized in that the clearance is set to -0.001 to -0.003 mm.   The helical internal gear machining broach according to claim 1 or 2, wherein the acute angle flank and the obtuse angle flank are cut simultaneously.

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