JP2004351609A - Broaching tool and broaching method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a broaching tool and a broaching method of broaching which finish a hollow hole formed in a highly hard material having hardness of 45-65 HRC, and perform broaching, even in a case of using a cutting blade formed from a carbide alloy, with less generation of chipping and abnormal abrasion in blade tip and with a long service life. <P>SOLUTION: In this broaching tool for finishing a hollow hole with multiple cutting blades 2 arranged in order of dimension in the longitudinal direction thereof, at least a finishing part of the cutting blade 2 is formed from a carbide alloy, and depth of cut-in per one blade of the cutting blades 2 is set at 5-15 μm in a cutting direction in case of a groove hole such as a spline hole or a ball groove, and at 3 μm - less than 9 μm in case of a round broach hole. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a broaching tool and a broaching method used for broaching for finishing a hollow hole made of a high hardness material having a hardness of 45 to 65 HRC (Rockwell hardness C scale).

Conventionally, as a broach for finishing a hardened material whose hardness after heat treatment is equivalent to 45 to 65 HRC, for example, it is disclosed in Patent Document 1. In this broach, a tool material constituting a finished cutting edge is made of a cemented carbide. Further, it is described that by coating each cutting edge with a hard coating and setting the rake angle of each cutting edge to -10 to -30 °, a good machined surface can be obtained by cutting a hard material. Further, by performing machining at a speed of 40 to 60 m / min using the broach, tool wear is suppressed.
JP 2001-239425 A

  However, with respect to each cutting edge of the broach of Patent Document 1, there is no description about the finishing allowance and the cutting amount per cutting edge of the broach. The cutting depth per blade is usually set to about 25 μm to 30 μm for spline holes and about 9 μm to 20 μm for round broach holes of carbon steel and alloy steel, respectively. This is because, when the groove is less than 20 μm in a slot such as a spline hole or a ball groove, and when it is less than 9 μm in a round broach hole, the cutting edge wears due to rubbing between the cutting edge and the work, and the tool life is shortened. Conventionally, in the broaching for finishing a hardened material having a hardness equivalent to 45 to 65 HRC after heat treatment, there is no established theory of the cutting depth. Conversely, when the cutting amount of one blade is reduced, there is a problem that the length of the broach becomes longer and the tool cost increases.

  An object of the present invention is to solve the conventional problems described above and to be used for broaching for finishing a hollow hole of a high-hardness material equivalent to 45 to 65 HRC after heat treatment, and the cutting edge material is a cemented carbide. Even in the case of (1), an object of the present invention is to provide a broaching tool and a broaching method capable of performing long-life broaching with little chipping and abnormal wear of the cutting edge.

Therefore, a first invention of the present invention is a broaching tool for finishing a hollow hole in which a large number of cutting edges are arranged in the longitudinal direction in a dimension order, wherein at least the finishing portion of the cutting edges is made of a material for the cutting edges. Is a cemented carbide, and the cutting amount of one blade is 5 μm to 15 μm in the slotting direction such as a spline hole or a ball groove in the cutting direction, and 3 μm to less than 9 μm in a round broaching hole. The above-mentioned problem has been solved. In addition, the surface of the cutting edge other than the rake face of each cutting edge was coated with a hard coating of TiAlN, so that a tool with higher wear resistance and a longer life was provided.
The second invention of the present invention is a method for finishing a hollow hole, wherein the pre-processing is performed after leaving a finishing allowance of 0.01 mm or more and 0.15 mm or less in a cutting direction of the finishing with respect to a finished product size, and after a heat treatment. A broach having a high hardness hardness of 45 to 65 HRC equivalent to a finished surface of a finished product using the broach tool according to any one of claims 1 to 3. The above-mentioned problem has been solved by a processing method.

Conventionally, in the broaching tool used in the processing before the heat treatment, the cutting amount per blade of the cutting edge of the broach is 25 μm to 30 μm in a slot hole such as a spline hole or a ball groove of carbon steel or alloy steel, and a round broach. In a hole, the cut amount is usually set to about 9 μm to 20 μm. This is because, when the groove is less than 20 μm in a slot such as a spline hole or a ball groove, and when it is less than 9 μm in a round broach hole, the cutting edge wears due to rubbing between the cutting edge and the work, and the tool life is shortened. When a high-hardness work material having a hardness equivalent to 45 to 65 HRC after the heat treatment is machined with the same cutting depth, chipping occurs at the cutting edge and the tool life is shortened. This is because the work material is hard, and the cutting edge for processing the work material is harder, so that chipping is likely to occur and has a brittle property.
According to the present invention, when processing a high hardness work material having a hardness equivalent to 45 to 65 HRC after heat treatment, it is considered that reducing chipping first is more important for extending the tool life than rubbing the cutting edge. The cutting amount of one blade of the broaching tool is limited to 5 μm to 15 μm in the cutting direction in a slot such as a spline hole or a ball groove, and 3 μm to less than 9 μm in a round broaching hole. Thus, the stress applied to the tip of the cutting edge was suppressed to a certain level, and chipping of the cutting edge could be suppressed. Further, since the material of the cutting edge is a cemented carbide, heat resistance and wear resistance are enhanced, and the tool is resistant to wear. If the cutting depth of one blade is less than 5 μm in the slot direction such as a spline hole or ball groove in the cutting direction and less than 3 μm in the round broach hole, the cutting edge wears due to the rubbing between the cutting edge and the work, and the tool life is shortened. Further, when the cut is made small, the overall length of the broach is prevented from increasing, and the cost of the broach is prevented from increasing. If the cutting amount of one blade exceeds 15 μm in a slot direction such as a spline hole or a ball groove in the cutting direction and is 9 μm or more in a round broach hole, chipping of the cutting edge occurs. In addition, in order to prevent the total length of the broach from increasing when the cut is made small and increase the cost of the broach, in the finishing process of the hollow hole, the cutting direction of the finishing process is 0.01 mm or more with respect to the finished product dimensions. It was pre-processed leaving a finishing margin of .15 mm or less. The reason why the finishing margin of 0.01 mm or more is set is that, in many cases, even if the pre-processed dimension is the final finished dimension, in the inner surface processing of the hollow part, the hole diameter is usually reduced by heat treatment deformation, so This is because even if the processing variation of the processing broach is considered, the point that the cutting allowance does not disappear is noticed. The inner surface broaching is a balanced cutting, and has the property of following the pre-processing, so even if the shaving margin is small, the shaving margin is not easily biased and the black scale is hardly generated, so very little shaving of about 0.01 mm It is possible to set an alternative. In addition, the finishing margin of 0.15 mm or less is determined in such a way that the heat treatment deformation may be distorted and the hole diameter may be partially increased depending on the shape of the work, and the broaching tool becomes long and does not become uneconomical. This is because it is necessary to give a margin to the allowance, but it is preferable to set as small as possible by observing the state of the heat treatment deformation of the target work.

  According to the first invention of the present invention and the configuration of the second invention of the present invention, it is used for broaching for finishing a hollow hole of a high hardness material having a hardness of 45 to 65 HRC, and the cutting edge material is a cemented carbide. However, there has been provided a broaching tool and a broaching method capable of performing long-life broaching with little chipping and abnormal wear of the cutting edge.

Preferably, in the broaching tool, after the hollow-hole machining surface is pre-processed leaving a finishing allowance and heat-treated, the hardness of the hollow-hole machining surface corresponding to 45 to 65 HRC (Rockwell hardness C scale) is reduced. By using a broach that finishes to the finished product dimensions, the coefficient of friction can be reduced, heat generation can be suppressed, wear can be suppressed, and tool life can be extended.
More preferably, the cemented carbide has an average WC particle size of 0.4 to 0.8 μm and a Co content of 5 to 15 wt%. It became excellent. If the average particle size of WC is less than 0.4, it is difficult to manufacture, and if it exceeds 0.8 μm, it tends to be chipped. If the Co content is less than 5 wt%, chipping tends to occur, and if it exceeds 15 wt%, the abrasion resistance decreases.

  1 is a side elevational view of a broach used for finishing after heat treatment according to an embodiment of the present invention, FIG. 2 is a plan view of a spline hole work to be processed by the broaching tool of FIG. 1, and FIG. FIG. 4 is an enlarged explanatory view of a machining groove portion of a spline hole work to be machined by the broaching tool of FIG. 4. FIG. 4 is a work of the spline hole work to be machined of FIG. It is explanatory drawing which shows each large diameter dimension of a processed part. The work to be processed by the broach according to the embodiment of the present invention shown in FIG. 2 is a spline large diameter groove 7 to 10 of a work 6 having four square splines on the inside diameter. The large diameter dimension of the finished product is φd1 = 40.0 mm, and before the heat treatment, the large diameter spline is processed to φd2 = 39.9 mm by a pre-processing broach. That is, pre-processing is performed while leaving a finishing margin of 0.1 mm in diameter with respect to the dimensions of the finished product. Next, the workpiece was carburized and quenched to have a surface hardness of 60 HRC. The carburization depth is about 1 mm. At this time, the inner diameter of the workpiece was reduced by the heat treatment deformation, and the large diameter of the spline after the heat treatment became φd3 = 39.8 to 39.85 (minimum value of φd3: φd3min = 39.8). FIG. 4 shows the relationship among d1, d2, and d3.

  FIG. 1 shows a broaching tool according to an embodiment of the present invention for finishing a spline hole work (a slot work such as a ball groove) as shown in FIG. The broaching tool for finishing is also similar in shape for round holes.) The broaching tool shown in FIG. 1 is a broaching tool for finishing a hollow hole in which a number of cutting edges 2 are arranged in the axial direction or longitudinal direction of a cutting edge portion 5 in dimensional order. The material of the cutting edge 2 is a cemented carbide, and the cutting amount of one cutting edge is 5 μm to 15 μm in the cutting direction in a slot such as a spline hole or a ball groove (3 μm to less than 9 μm in a round broach hole). The broach tool of FIG. 1 has a large number of cutting edges 2 following the grip portion 1. The cutting edge 2 is made of a cemented carbide having a WC average particle diameter of 0.7 μm and a Co content of 11 wt%. Reference numeral 5 denotes a cutting edge portion, and the cutting edge surface other than the rake face of each cutting edge 2 is made of hard TiAlN. The coating of the film is applied. The first half 3 of the cutting edge portion 5 has a cutting amount per cutting edge of 15 μm, and the rear half portion 4 as the finishing portion 4 for finishing the cutting edge portion 5 has a cutting amount of 10 μm per cutting edge. . That is, as shown in FIG. 3, the cut by such a broach has a total cut amount L1 = (d1−d3min) /2=0.1 mm, the first half cut amount L2 of the cutting edge portion 5 = 15 μm, and the second half cut amount. When L3 = 10 μm, the number of cutting edges in the first half 3 of the cutting edge portion 5 was 4, and the number of cutting teeth in the second half 4 was 4. Further, the pitch of the broach blades of the cutting edge portion 5 was set to 15 mm, and the total length of the broach cutting edge portion was set to about 120 mm, so that the broach was compact and economical.

When a large diameter spline after heat treatment of a workpiece as shown in FIG. 2 was machined with such a broach, the occurrence of chipping at the cutting edge was significantly reduced compared to the case where the cutting depth was 25 μm, and the tool life was more than twice as long. .
The present invention is characterized in that the cutting amount of one blade is 5 μm to 15 μm in a slot direction such as a spline hole or a ball groove in a cutting direction (3 μm to less than 9 μm in a round broach hole). When the cutting amount is changed between the cutting edge and the finishing cutting edge, a certain effect can be obtained even if the cutting depth of one finishing cutting edge is set to 15 μm or less. This is because chipping of the finished tooth can be delayed even if the life of the rough cutting edge comes earlier.
In addition, the present invention is not limited to this embodiment, and can be similarly applied to involute spline large diameter machining, tooth flank machining, inner diameter machining, or any combination thereof, CVT ball groove machining, inner diameter machining, or a combination thereof. .
[Effects of Best Mode for Carrying Out the Invention]

According to the configuration of the broach tool of the embodiment of the present invention, in the finishing of a hollow hole made of a high-hardness material, after the heat treatment, the cutting amount of one cutting edge in the cutting direction is 5 μm to 5 μm in a slot such as a spline hole or a ball groove. Since the finishing is performed with a broach of 15 μm (3 μm to less than 9 μm in a round broach hole), chipping and abnormal wear of the cutting edge are reduced, and long-life broaching can be performed. In particular, even if the material of the cutting edge is a cemented carbide, the life is long without chipping. In addition, since the pre-processing was performed with a finishing allowance of 0.01 mm or more and 0.15 mm or less in the cutting direction of the finishing process with respect to the finished product dimensions, unprocessed black scale does not remain, and the cutting amount of one blade is Even with a carbide broach having a size of 15 μm or less, the total length of the broach is short, and it is economically excellent. Furthermore, since the surface of the cutting edge other than the rake face of each cutting edge 2 is coated with TiAlN, a tool that is more resistant to wear and has a longer life is provided.
Preferably, the WC has an average particle diameter of 0.4 to 0.8 μm and a Co content of 5 to 15 wt%, so that the wear resistance is excellent even under the condition of a small cut amount and a large amount of rubbing.

The elevation side view of the broach tool used for the finishing after heat processing of an embodiment of the invention. FIG. 2 is a plan view of a spline hole work to be machined by the broach tool of FIG. 1. FIG. 2 is an enlarged explanatory view of a processing groove of a spline hole work to be processed by the broach tool of FIG. 1. FIG. 3 is an explanatory diagram showing respective large-diameter dimensions of a workpiece processed portion of the spline hole workpiece to be processed in FIG. 2 before being subjected to heat treatment, after being subjected to heat treatment, and after being subjected to finish broaching.

Explanation of reference numerals

2. Cutting edge 6. Spline hole work 7-10. Spline large diameter groove

Claims (4)

A broaching tool for finishing a hollow hole in which a number of cutting edges are arranged in the longitudinal direction in a dimension order, wherein at least a finishing portion of the cutting edges is made of cemented carbide material of the cutting edges, and one cutting edge is provided. A broaching tool characterized in that the cutting amount is 5 μm to 15 μm for a slot such as a spline hole or a ball groove in the cutting direction, and 3 μm to less than 9 μm for a round broach hole. The broach tool is a finished product in which the hollow-hole work surface is pre-processed with leaving a finishing allowance, and the hardness after heat treatment is 45 to 65 HRC (Rockwell hardness C scale). The broaching tool according to claim 1, wherein the broaching tool is a broach for finishing to dimensions. 3. The broach tool according to claim 1, wherein the cemented carbide has an average particle size of WC of 0.4 μm to 0.8 μm and a Co content of 5 wt% to 15 wt%. 4. In the finishing process of the hollow hole, the hardness after the heat treatment is 45 to 65 HRC equivalent to that of the finished product. A broaching method comprising finishing a hardened hollow-hole work surface to a finished product size using the broaching tool according to any one of claims 1 to 3.

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