JP4118055B2 - Broaching tool for machining hard materials - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a broaching tool for machining an inner diameter hole of a high-hardness material having an R shape with a small curvature radius in a petal shape.
[0002]
[Prior art]
As a broaching tool for processing a hard material with a hardness equivalent to HRC 35-55, for example, in Japanese Patent Laid-Open No. 7-195228, the cutting edge of the broaching tool is made of powder high speed steel or cemented carbide and coated with a hard coating Japanese Patent Application Laid-Open No. 6-315820 discloses a rough cutting blade having a corrugated cutting edge shape and a corrugating shape with respect to the front blade in the cutting direction. A broaching tool is disclosed in which several intermediate blades are provided between the rough cutting blade and the intermediate finishing blade to smooth the cutting surface of the rough cutting blade. However, there is no disclosure about the inner diameter drilling of a high-hardness material having an R shape with a small radius of curvature in the shape of a petal. An R-shaped cutting blade continuous in the axial direction for cutting the machining allowance along the R-shape was used.
[0003]
In such a conventional broach as shown in FIG. 4, when cutting at a high speed of 10 m / min or more, the chips to be cut with the R-shaped cutting blades tend to be wound toward the center of the R shape, so that the chips are small. It becomes difficult to wind. Especially when machining high-hardness materials, the chips are hard, so they fold into a contracted state with a small degree of freedom, as shown in Fig. 5, resulting in chips that do not flow easily and shorten the life of the broach tool. It was.
[0004]
Furthermore, Corona's “New Revised Precision Handbook”, edited by the Precision Machinery Society, page 354, shows the “progressive cutting method” shown in FIG. 6 as an internal broaching method for round holes in forged and cast holes. Proposed. In this method, the No.1 blade to No.18 blade are broaching methods in which even-numbered blades and odd-numbered blades have different cutting positions, and the blades are arranged so as to cut alternately in the radial direction and in the horizontal direction. . However, this method requires not only a very complicated and time-consuming broach, but also cuts alternately in the radial direction and in the lateral direction. There was a problem similar to that of the broach shown in FIG.
[0005]
[Problems to be solved by the invention]
An object of the present invention is a broaching tool for machining an inner diameter hole of a high-hardness material having a petal-like R-shape with a small radius of curvature, in which chips are not wound toward each other even in high-speed cutting. Is to provide.
[0006]
[Means for solving the problems]
For this reason, the present invention is a broaching tool for machining an inner diameter hole of a high hardness material having a petal-like R-shape with a small radius of curvature. The broaching tool divides the R-shape into two, and broachs each of the R-shapes divided into two. Thus, the width of each pair of broach blades corresponding to each R shape divided into two is gradually reduced so that the cutting direction of the outer end of each blade of the broach advances along the circular arc of the R shape. There is provided a broaching tool for machining a high-hardness material characterized in that, in broaching, chips are cut along an arc in a broaching process so as to reduce a cutting load in an R-shaped radial direction. This solves the above-described problems of the present invention.
[0007]
【The invention's effect】
With this configuration, in the broaching process, the cutting direction of the outer end portion of each blade of the broach advances along the R-shaped circumferential arc, so that the cutting load in the R-shaped radial direction is reduced. And provides a broaching tool that can be machined with high accuracy, and the chip is cut along a circular arc and has a petal-like shape with a small radius of curvature. However, even in high-speed cutting at 10 m / min or more, the cutting direction of the outer end of each broach blade advances along the circular arc of the R shape, so that the chips are directed toward the center of the R shape. This provides a broach tool that generates easy-to-wind chips corresponding to a cutting blade that processes each side without winding, and improves the life of the broach tool.
[0008]
Preferably, each of the pair of broaching blades is the R-shaped finishing cutting blade as a finishing cutting edge, and the cutting allowance is 8 to 15 μm, so that chips can be wound even in high-speed cutting of 10 m / min or more. Easy to get a beautiful finish.
Further, the cutting edge of the broach tool is made of powder high speed steel or cemented carbide, and the life of the broach tool can be further improved by applying a hard coating.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a cross-sectional view of an inner diameter hole of a high hardness material having an R shape with a small radius of curvature, in which the present invention is used, and a hatched line shows an example of a processed portion, and FIG. It is explanatory drawing which shows the broach cutting condition by the broach tool for high-hardness-material processing of the processing location which has an R shape of this embodiment of this invention. This hardness is a heat-treated steel having a hardness of around HRC 60. The broaching tool of the present invention is a broaching tool for drilling inner diameter holes of a high hardness material having a petal-like R-shaped radius of curvature 100, ... 110 (final finished shape). 110 is divided into two by radial lines 70 and 72 , and the cutting direction of the outer end of each blade of the broach is along the circular arc of the R shape so that each R shape divided into two is broached. In order to advance, the blade has a cutting edge in which the width of each blade of the broach corresponding to the length of each side 41 , 42 , 51 , 52 , 61 , 62 of the broaching blade gradually decreases. 110 is the final finished shape, 200 is the total machining allowance, 120 is the machining allowance per blade, and 121 and 122 are the cutting amounts per blade.
[0010]
With such a configuration, in the broaching process using the broaching tool for machining a high hardness material according to the embodiment of the present invention, the chips are cut along the arc at the outer end of each blade of the broach and cut as shown in FIG. Since the chip 80 is discharged, in a broaching tool for drilling an inner diameter hole of a high-hardness material having a hardness HRC of 40 or more having a petal-like R-shaped radius of curvature 100, ... 110 Even in high-speed cutting such as min or more, the cutting direction of the outer end of each broach blade advances along the circular arc of the R shape, so that the chips do not wind toward the center of the R shape. To provide a broaching tool that generates easy-to-wind chips corresponding to the cutting edge that processes each side, and to reduce the cutting load in the R-shaped radial direction, and to improve the life of the broaching tool It was Tsu name.
[0011]
Preferably, the polygonal cutting edge of the broaching tool is an R-shaped 100,..., 110 cutting edge as a finishing cutting edge (not shown), and the cutting allowance of one cutting edge is 8 to 15 μm. Even in high-speed cutting as described above, chips can be easily wound and a beautiful finish can be obtained.
Further, the cutting edge of the broach tool is made of powder high speed steel or cemented carbide, and the life of the broach tool can be further improved by applying a hard coating.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an example of an inner diameter hole of a high-hardness material having an R shape with a small curvature radius, which is a petal shape, in which the present invention is used;
FIG. 2 is an explanatory view showing a broach cutting state of a machining portion having one R shape of the inner diameter hole of FIG. 1 by a high hardness material machining broach tool according to an embodiment of the present invention.
3 is a perspective view of chips that have been broached by the broach tool of FIG. 2; FIG.
FIG. 4 is an explanatory view showing a broach cutting situation with a conventional broach tool.
FIG. 5 is a perspective view of chips broached by a conventional broaching tool.
FIG. 6 is an explanatory diagram of a round hole inner surface broaching method “progressive shape cutting method” described in Corona “New Revised Precision Handbook” edited by Seiki Gakkai, page 354.
[Explanation of symbols]
41 , 42 , 51 , 52 , 61 , 62・ ・ Each side of each blade of broach
70 , 72 ... Radial direction line
100, ... 110 .... R shape with small curvature radius of petal shape

Claims (3)

In a broaching tool for machining the inner diameter hole of a high hardness material having a R shape with a small radius of curvature like a petal shape, the broaching tool is divided into two parts, and each broaching part is broached so that each R shape divided into two parts is broached. as cutting direction of the outer end of the blade advances along the circumferential direction of the arc of R shape having a cutting edge pair brooch width of each blade corresponding to each R shape bisected gradually decreases In the broaching process, a cutting tool is cut along an arc so as to reduce a cutting load in the radial direction of the R shape. 2. The broaching tool for machining a high-hardness material according to claim 1, wherein each of the pair of broaching blades is the R-shaped finishing cutting blade as a finishing cutting blade and has a machining allowance of 8 to 15 [mu] m. 3. The broaching tool for machining a high hardness material according to claim 1 or 2, wherein the cutting blade of the broaching tool is made of powder high speed steel or cemented carbide and is coated with a hard coating.

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