JPH11226814A - brooch - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To reduce the occurrence of flank wear of the cutting edge of a broach, prolong the service life of the broach, and prevent work clamp failure and the like. SOLUTION: The clearance angle φ of the flank 5 of the outer peripheral cutting edge 4 of the broach 1 is 5 ° to 10 °, and the rake angle θ of the rake face 6 is −.
5 ° to 0 °. It is good to use as a broach for cutting an outer surface broach and further for a continuous broaching machine.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an outer surface broach for processing a surface of a workpiece. In particular, the present invention relates to a broach suitable for roughing and semi-finishing of a semi-circular portion of a connecting rod or a cap, which is one of components of a combustion engine for an automobile.

[0002]

2. Description of the Related Art Conventionally, a connecting rod 10 shown in FIG. 4 and a broaching machine for rough / medium finishing of semi-circular portions 12, 13 of a cap 11 shown in FIG. This is performed by using a continuous broaching machine that performs processing while attaching and moving the rod to the chain via a jig with the processing surface 12 of the rod facing upward. As shown in FIGS. 2 and 3, the broach 1 for a continuous broaching machine is formed by forming a large number of cutting edges 4 on the main body 2 of which the diameter gradually increases toward the final desired shape of the work. The flank 5 of the blade usually has a clearance angle φ of about 1 ° to 4 °.
However, the rake face 6 is usually provided with a rake angle θ of about 10 ° to 16 °.

[0003]

The life of such a conventional broach depends on the wear width of the flank, but a longer life is required. Increasing the clearance angle of the cutting edge reduces wear on the flank, but increasing the clearance angle reduces the force of the broach cutting edge pressing the work against the work clamp jig as a back force during cutting, resulting in poor work clamp. However, there is a problem that the clearance angle is likely to occur, and the clearance angle cannot be increased. The rake angle of the workpiece is -5 ° to 15 ° for brass or bronze, or a hard material coated with a hard cutting edge (HRC 35 to 5).
5) For cutting, JP-A-7-195228 discloses
A rake angle of 18 ° to 3 ° is used, but nothing is disclosed about the relationship with the clearance angle.

In view of the above problems, it is an object of the present invention to reduce the occurrence of flank wear, extend the life of a broach, and prevent work clamp defects.

[0005]

According to the present invention, the clearance angle of the outer peripheral cutting edge is 5 ° to 10 °, and the rake angle is -5 ° to 0 °.
The above-mentioned problem was solved by providing a broach with an angle of °. By increasing the clearance angle of the outer peripheral cutting edge, the flank wear can be suppressed, and at the same time, by setting the rake angle to be small or negative, the cutting component acts in the direction of pressing the work against the clamp jig. Thus, the work can be reliably clamped while reducing the flank wear width.

The reason why the clearance angle of the outer peripheral cutting edge is set to 5 ° to 10 ° is that when the clearance angle is less than 5 °, there is no much difference from the conventional flank wear width by 10%.
If the angle is more than °, the blade angle becomes small and chipping and breakage are likely to occur. The reason why the rake angle is set to -5 ° to 0 ° is that if the rake angle is more than 0 °, the pressing force is insufficient, and if it is less than -5 °, the sharpness deteriorates and the processed surface roughness deteriorates.

[0007] Such a broach is an inner broach for easily applying a cutting reaction force to the entire broach (for example, a round broach, a long hole broach, a D-shaped broach, a regular polygonal broach, an involute spline broach, a key groove broach, and a reverse key groove). It is suitable for external broaching (eg, a broach for a connecting rod, a broach for a bearing cap, a broach for a turbine blade implant groove, a broach for a keyhole, etc.) in which a cutting reaction force is applied to one surface of the broach with respect to the broach.

In particular, the present invention is effective for a continuous broaching machine that performs broaching by fixing the blade portion of a broach used for a broach for a connecting rod downward and moving the connecting rod with the processing surface of the bronze upward.

[0009]

An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory view showing the relationship between the cutting edge of a broach of the present invention and a workpiece. The same parts as those in the related art are denoted by the same reference numerals, and description thereof is omitted. In the broach of the present invention, a large number of cutting edges 4 are formed on the main body 2 as shown in FIG. In the present invention, as shown in FIG. 1, the clearance angle φ of the flank 5 of the cutting edge 4 is 5 ° to 10 °, which is larger than the conventional clearance angle. Also, the rake angle θ of the rake face 6 is −5 ° to 0 °.
° and is formed to be smaller than the conventional rake angle.

According to this configuration, when the clearance angle φ is 5 ° to 10 ° as shown in FIG. 1, the flank wear width is reduced, but the back force F2 is reduced. However, the rake angle is -5 ° ~
Since it is 0 °, the cutting resistance F1 due to the workpiece 7 increases, but the increase in the back component force F2 pressing against the workpiece becomes more than twice, and the workpiece is reliably pressed against the clamp jig.

[0011]

Next, an embodiment of the present invention will be described. Using the continuous broaching machine of the broach of the present invention and the conventional broach, semifinishing of the semi-circular portion 12 of the forging steel connecting rod shown in FIG. 4 was performed. The results are shown in Tables 1 and 2. Table 1 shows the results of measuring the change in the magnitude of the back force F2 and the flank wear width after a cutting length of 200 m. Table 2 shows the results of measuring the processed surface roughness.

[0012]

[Table 1]

[0013]

[Table 2]

As shown in Table 1, the conventional flank angle of 3 ° and the rake angle of 15 ° (No. 1) did not change the back force, but the flank wear width was 0.08 mm. No
In No. 6, No. 7), the back force increases and the flank wear width is 0.
04, 0.05 mm. On the other hand, simply increase the clearance angle to 6
° to 9 ° while increasing the rake angle to 5 ° as before
In the conventional example (No. 2 to No. 5) changed to １５15 °, the flank wear width is halved from that of No. 1, but the back force is largely dispersed, and particularly, the change of the back force between the initial machining and after the cutting length of 200 m is large. It can be seen that the component force between the broach and the workpiece is not stable. Therefore, as shown in Table 2, the processed surface roughness is slightly increased. Note that the clearance angle is 10
When it was more than °, the processing vibration was large and the surface roughness was deteriorated.

[0015]

In the present invention, the clearance angle of the outer peripheral cutting edge is set to 5 ° to 10 ° to suppress the flank wear width, and at the same time, the rake angle is set to -5 ° to 0 °, and the cutting component force clamps the work. The work can be reliably clamped while reducing the flank wear width by acting in the direction in which the work piece is pressed against the workpiece, so that the life of the broach can be prolonged and defective work clamping can be prevented.

[0016] Therefore, it is suitable for the outer surface broaching. Furthermore, it became useful in continuous broaching.

Further, as described above, in the present invention, the flank wear width is reduced to about 1/2 as compared with the conventional broach, so that the number of regrinds can be increased. Also, when re-grinding the same amount as the conventional one, the effect of the number of processings approximately twice that of the conventional one can be expected.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a relationship between a cutting edge of a broach of the present invention and a workpiece.

FIG. 2 is a partially enlarged view of a conventional cutting edge.

FIG. 3 is a plan view in which a connecting rod and a part of a cap processing broach main body are omitted.

FIG. 4 is a front view of a connecting rod.

FIG. 5 is a front view of the connecting cap.

[Explanation of symbols]

 Reference Signs List 1 broach 2 broach body 4 cutting edge 5 flank 6 rake face θ rake angle φ clearance angle

Claims (3)

[Claims] 1. A broach wherein the clearance angle of the outer peripheral cutting edge is 5 ° to 10 ° and the rake angle is -5 ° to 0 °. 2. The broach according to claim 1, wherein the broach is for cutting an external broach. 3. The broach according to claim 1, wherein said broach is for a continuous broaching machine.