JPS6346188Y2 - - Google Patents

Description

[Detailed description of the invention] Technical field This invention is applicable to round brooches, spline brooches,
This invention relates to broaches such as Surf Ace broaches, and particularly to the structure of their cutting edges.

Prior Art Conventionally, a broach generally has a rough finishing edge region 10 consisting of a plurality of cutting edges with a constant depth of cut and a constant clearance angle (φ ₃ ), and a rough finishing edge region 10 with a constant depth of cut and a constant clearance angle (φ ₄ ). It consists of a semi-finishing blade area 11 consisting of a plurality of cutting edges whose clearance angle (φ 3 ) is smaller than the clearance angle (φ ₃ ) of the cutting edge of the rough finishing blade area, and a finishing blade area where the depth of cut of each cutting edge is zero.

Problems to be Solved by the Invention By the way, when the cutting edge of a broach wears out during cutting work, the rake face is re-ground as shown by the dotted line 13 in FIG. 3, but in the above conventional structure, By this re-grinding, the rough finished blade area 10 with a large relief angle for each broach axial dimension Δl is
At cutting edge i+4, the blade height decreases by Δltanφ ₃ , whereas at cutting edge i+5 in the semi-finished edge region 11 with a small clearance angle, the blade height decreases by only Δltanφ ₄ , and the difference (Δltanφ ₃ − Δltanφ ₄ ) The difference in blade height, that is, the depth of cut, increases each time grinding is performed, and eventually the depth of cut _b3 of the cutting edge i+5 becomes larger than the depth of cut _b4 of the finishing edge area 10, and when it breaks during cutting, Due to this problem, there was a limit to the number of times of regrinding (regrinding amount Δl).

That is, for example, the cutting edge 1 in the rough finishing edge area,
..., i+4, each relief angle φ ₃ is 2°, each depth of cut b ₄ is 0.04 mm, cutting edges i+5, i+ in the semi-finishing edge area
6. Relief angle φ ₄ of i+7 is 1°, and depth of cut is each
When 0.03mm, 0.02mm, and 0.01mm, now Δl=
If re-grinding is performed by 2 mm from the rake face side, the cutting depth of the cutting edge at the frontmost part of the semi-finishing edge area 11 at i+5 will be b ₃
is b ₃ = a ₂ + Δl (tanφ ₃ − tanφ ₄ ) = 0.03 + 2 × (tan2゜−tan1゜) = 0.065, and the depth of cut of the cutting edge in the rough finishing blade area 10 is 0.04
It is larger than mm.

One way to solve this problem is to set all the relief angles of the cutting blades to the same value, so that the depth of cut of the cutting blades will not increase even after re-grinding, but this poses a problem in that the precision of the finished cutting dimensions deteriorates.

Therefore, the purpose of the present invention is to make the amount of increase in the depth of cut of the cutting edge at the forefront of the semi-finishing blade region due to re-grinding smaller than in the case of the conventional example described above, thereby making it possible to increase the number of times of re-grinding compared to the conventional example. Our goal is to provide brooches.

Means for Solving the Problems In order to solve the above problems, the present invention provides a double cutting edge between the rearmost cutting edge of the rough finishing edge area and the frontmost cutting edge of the medium finishing edge area. By absorbing the change in the depth of cut during re-grinding, that is, the increase in the difference in blade height, the depth of cut of the cutting edge at the forefront of the above-mentioned semi-finishing blade area is greater than the depth of cut of the cutting blade in the rough-finishing blade area. It is configured to include a cutting blade for adjusting the blade height which becomes smaller. That is, a cutting blade 2 for blade height adjustment is provided at the boundary between the rough finishing blade area 10 and the medium finishing blade area 11, and the cutting blade 2 is
The clearance angle (φ ₂ ) is the same as the clearance angle (φ ₂ ) of the cutting edge 3 in the semi-finishing blade area 11, and the blade height (distance from the broach axis) is equal to that of the cutting edge at the rearmost part of the rough finishing blade area 10. It was configured to be the same as the blade height.

Effects of the invention According to the above configuration, even if the depth of cut between the rearmost cutting edge in the rough finishing edge area and the cutting edge at the frontmost part in the semifinishing edge area increases due to regrinding, the gap between the two cutting edges increases. With the included blade height adjustment cutting blade, the depth of cut between the two cutting blades can be adjusted by
It is divided into the depth of cut between the cutting edge at the forefront of the medium finishing blade area and the cutting edge for blade height adjustment, and the depth of cut between the cutting edge at the rearmost part of the rough finishing blade area and the cutting blade for blade height adjustment. , by making sure that each depth of cut is smaller than the depth of cut of each cutting edge in the rough finishing edge region, and by making the amount of increase in the depth of cut of the cutting edge at the forefront of the medium finishing edge region smaller than in the conventional case,
The number of times of re-grinding can be increased compared to the conventional method, and the life of the broach can be extended. That is,
Before re-grinding, the cutting edge 1 at the rear of the rough finishing edge area
(relief angle φ ₁ ) and the above-mentioned blade height adjustment cutting blade 2 (relief angle φ ₂ ), the depth of cut is set to zero, and a medium finishing blade is used for the blade height adjustment cutting blade 2 (relief angle φ 2 ). The height of the cutting edge 3 (relief angle φ ₂ ) at the forefront of the area was increased by a ₁ to secure the depth of cut a ₁ , but each cutting edge was reground by the axial dimension Δl. After that,
The blade height of the cutting edge 1 at the rearmost part of the rough finishing blade area is reduced by Δltanφ ₁ , and the blade height of the cutting blade 2 for blade height adjustment is decreased by Δltanφ ₂ , so that Δl(tanφ ₁ − tanφ ₂ )
The blade height of the cutting blade 2 for blade height adjustment increases by , while the blade height of the cutting blade 3 at the frontmost part of the medium finishing blade area decreases by Δltanφ ₂ , and the blade height of the cutting blade 2 for blade height adjustment decreases by Δltanφ 2. In other words, the depth of cut b ₂ is (a ₁ +
Δltanφ ₂ )−Δltanφ ₂ = a ₁ and the original depth of cut of both cutting edges 2 and 3 becomes a ₁ . Therefore, the blade height difference between cutting blades 1 and 3 would normally be (a ₁ +Δltanφ ₁ −Δltanφ ₂ ), but with the provision of cutting edge 2, the blade height difference between cutting blades 1 and 2 (Δltanφ ₁ −Δltanφ ₂ ) and the difference in height a ₁ between cutting edges 2 and 3, and there is a period when the depth of cut of the cutting edge in the boundary area becomes larger than the depth of cut of the cutting edge in the rough finishing edge area. It is effectively delayed and the number of re-grinding can be increased.

Embodiments The present invention will be specifically described below based on illustrated embodiments.

Cutting blades 1, 2, 3 near the boundary between the rough finishing blade area 10 and the intermediate finishing blade area 11 of the broach according to this embodiment
is shown in Figure 1. 1 is the cutting edge at the rearmost part of the rough finishing blade area 10, 2 is the cutting blade for blade height adjustment located at the boundary between the above two areas 10 and 11, and 3 is the cutting edge at the frontmost part of the medium finishing blade area 11. .

The relief angle of the cutting edge 1 is φ ₁ , the relief angle of the cutting edge 2 is φ ₂ ,
The depth of cut between the cutting edge 1 and the cutting edge 2 is 0, and the relief angle of the cutting edge 3 is _φ2.The depth of cut of the cutting edge 3 with respect to the cutting edge 2 is _a1 .

Therefore, the cutting edge 2 is the cutting edge 3 in the semi-finishing blade area 11.
and the clearance angle φ ₂ are the same, and the depth of cut is a ₂ , while the clearance angle is different from that of the cutting edge 1 in the rough finishing edge area 10. The blade height shall be the same.

When the rake faces of the cutting blades 1, 2, and 3 configured in this manner are reground by Δl as shown by the dashed line 4 in FIG. 1, the depth of cut of the cutting blade 2 relative to the cutting blade 1 becomes b ₁
is b ₁ = 0 + Δl (tanφ ₁ − tanφ ₂ ), while the depth of cut of cutting edge 3 relative to cutting edge 2 b ₂
is _b2 = _a1 +Δl( _tanφ2 − _tanφ2 )= _a1 .

As an example, using the numerical values in the above conventional technology,
Relief angle φ ₁ = 2°, φ ₂ = 1°, Δl = 2 mm, and a ₁ = 0.03 mm.

b ₁ = 0 + 2 x (tan2゜-tan1゜) = 0.035mm b ₂ = 0.03 + 2 x (tan1゜-tan1゜) = 0.03mm, and the depth of cut of the cutting edge in rough finishing blade area 10 is 0.04
Both b ₁ and b ₂ are smaller than mm.

Note that the other configurations of the broach according to this embodiment are the same as the conventional one, so the explanation will be omitted.

According to the above embodiment, by providing the cutting blade 2 for blade height adjustment, even if each cutting blade is reground by Δl,
The depth of cut b ₁ of the cutting edge 2 relative to the cutting edge 11 is Δltanφ ₁ −Δltanφ ₂ , and the depth of cut b ₂ of the cutting edge 3 relative to the cutting edge 2 is (a ₁ +Δtanφ ₂ )−Δtanφ ₂ = a ₁ , and both depths of cut are It is effective when the depth of cut is smaller than the depth of cut of the cutting edge in the rough finishing edge region 10, and the depth of cut of the cutting edge at the frontmost part of the intermediate finishing edge region 11 is larger than the depth of cut of the cutting edge in the rough finishing edge region 11. This allows the number of times of re-grinding to be increased compared to the conventional method, extending the life of the broach.

That is, the depth of cut b ₂ =a ₁ of the cutting edge 3 is always smaller than the depth of cut of the cutting edge in the rough finishing edge region 10 . On the other hand, the depth of cut b ₁ of the cutting edge 2 is Δl(tanφ ₁ −
_tanφ2 ). From this value, it is theoretically possible that when grinding progresses and Δl exceeds a certain value, the depth of cut b ₁ may become larger than the depth of cut of the cutting edge in the rough finishing edge region. However, since the depths of cut b 1 and b ₂ of cutting edges 2 _and 3 are definitely smaller than the conventional depth of cut, that is, the value of b ₁ + b ₂ above, the increase rate of the depth of cut with respect to grinding is lower than that of the conventional one. It's also small. Therefore, at least the time it takes to reach a certain value becomes longer than before, and the number of times of re-grinding can be increased, and the life of the broach is reliably extended compared to before.

[Brief explanation of the drawing]

1 is an explanatory cross-sectional view of the cutting edge at the boundary between the rough finishing blade area and the intermediate finishing blade area of a broach according to an embodiment of the present invention; FIG. 2 is an explanatory cross-sectional view of the main part of a conventional broach; FIG. 3 is an explanatory cross-sectional view of the cutting edge at the boundary between the rough-finishing blade area and the semi-finishing blade area of the broach shown in FIG. 2. 1, 2, 3... Cutting blade, 4, 13... Regrinding line,
10... Rough finishing blade area, 11... Medium finishing blade area,
12... Finishing blade area.

Claims (1)

[Scope of utility model registration request] A rough finishing blade region 10 consisting of a plurality of cutting blades with a constant depth of cut and a constant clearance angle (φ ₁ ), and a rough finishing blade region 10 with a constant depth of cut and a constant clearance angle (φ ₂ ); In a broach equipped with a semi-finishing edge region 11 consisting of a plurality of cutting edges smaller than the clearance angle (φ ₁ ) of the blade, a cutting edge 2 for adjusting the blade height is provided at the boundary between the two regions, and the cutting edge 2 is , the clearance angle (φ ₂ ) is the same as the clearance angle (φ ₂ ) of the cutting blade 3 in the semi-finishing blade area 11, and the blade height is the same as the blade height of the cutting edge at the rearmost part of the rough finishing blade area 10. A brooch featuring.