JP2005096042A - Broaching tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a broaching tool for finishing a high hardness material suppressing an influence of wear due to abrasion and having a long service life. <P>SOLUTION: In this broaching tool 1 for finishing the high hardness material of hardness 45 to 65HRC, many cutting edges 2 having cutting edge dimensions formed to be successively larger toward a finishing edge 2f are provided in the longitudinal direction. The finishing edge 2f is constituted of two or more edges. The edges adjacent to each other are made equal or smaller toward a rear side of a broach within the range from a maximum value to a minimum value of a broach finishing dimension allowance difference. A final finishing dimension edge n is made smaller than the first edge of the finishing edge 2f. A relief angle θ of the cutting edge of the finishing edge 2f is made ≥1.1° and ≤2.0°, and a straight land is not provided. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a broach tool used for finishing an internal gear, a spline groove, a ball spline groove, and various surface shapes, and particularly to a broach tool used for finishing a high hardness material having a hardness of 45 to 65 HRC.

Conventionally, a finishing blade of a broach tool is usually composed of two or more cutting blades having the same dimensions, and a straight land is provided. Even if these finishing blades have the same size, all the blades act as cutting edges due to elastic deformation of the workpiece, eccentricity between the workpiece and the broach, or the like. For this reason, due to rubbing that occurs during broaching, the finished blade becomes more worn than a rough blade that does not have a straight land on the cutting edge. Therefore, in Patent Document 1, the finishing blades are divided into a plurality of sets of 2 to 3 blades, and the dimensions of each set are stepwise toward the final set within the range from the maximum value to the minimum value of the broach finish dimension tolerance. The clearance angle is gradually reduced toward the final set in the range of 1 ° to 0 °, and straight lands are provided on the finishing blade of the final set, and the cutting blades other than the final set are straight. There are cutting blades that do not have lands and suppress the effects of rubbing.
Japanese Utility Model Publication No. 5-36569

  However, when finishing a hard material having a hardness of 45 to 65 HRC (Rockwell hardness C scale) with the broach tool described in Patent Document 1, the cutting reaction force is large, and the flank of the cutting edge is rubbed. Furthermore, in high-speed cutting of 40 m / min or more usually performed in broaching of a hard material, there is a problem that the wear of the blade edge is extremely accelerated due to heat generated by rubbing, making it difficult to apply with a hard material.

  The present invention has been made to solve such problems of the prior art, and it is an object of the present invention to provide a broaching tool for finishing a long-life, high-hardness material in which the influence of abrasion due to rubbing is suppressed.

  In the present invention, a broaching tool for finishing a high-hardness material having a hardness of 45 to 65 HRC in which a number of cutting blades having large cutting edge dimensions formed in order toward the finishing blade are provided in the longitudinal direction. Two or more blades, and adjacent blades within the range of maximum and minimum broaching dimensional tolerances are made equal or smaller toward the back of the broach, and the final finishing size blade is smaller than the first blade of the finishing blade The above-mentioned problem has been solved by providing a broaching tool that is made smaller, the clearance angle of the cutting edge of the finishing blade is 1.1 ° to 2.0 °, and does not have a straight land. ).

  That is, the clearance angle of each cutting edge of the finishing blade is 1.1 ° or more and 2.0 ° or less, and all the finishing blades including the final finishing dimension blade, that is, the final assembly described in Patent Document 1, are free of straight lands. Therefore, even if a large cutting reaction force due to processing of a high hardness material having a hardness of 45 to 65 HRC is applied, the flank of the cutting edge is less rubbed. Thereby, even at a high speed cutting of 40 m / min or more, the wear of the blade edge is suppressed to a small level.

  In addition, when the first edge of the finishing blade and the cutting edge having the same dimensions as the first blade after the broaching are worn out, the worn cutting edge is reground to form a new cutting edge. As a result, the size of the reground cutting edge gradually decreases, and the size of the reground cutting blade and the non-reground cutting blade following the reground blade become the same. Here, since all the finishing blades are within the broach finish dimension allowable range, both the re-grinding blade and the non-re-ground grinding blade are finished blades, and the finished workpiece is within the allowable range even when finishing cutting is performed. . At this time, the cutting edge whose size is still lower than that of the re-grinding blade will not be involved in broaching and will remain as a spare blade. Thereafter, the final finished dimension blade is involved in broaching while repeating similar wear and regrinding. The broaching life is reached when the final finished dimension blade is worn by broaching and all finished blades are out of the allowable dimensions of the finished workpiece. In addition, in the text, there are descriptions of the front and the rear with respect to the broach tool.

  Moreover, it was set as the broach tool which has a 1 or more cutting blade with the same dimension following the 1st blade of a finishing blade (Claim 2). That is, by providing a plurality of cutting blades having the same dimensions behind the first blade of the finishing blade, the processing dimension of the workpiece in the initial state broaching is further stabilized. At this time, even if the subsequent cutting edges gradually decrease in size toward the back of the broach, after re-grinding, they will be the same as the cutting edge dimensions of the first cutting edge of the finishing edge, and both will become a finishing edge. Therefore, the processing dimension is stabilized. In addition, it is preferable to use 2 to 3 cutting edges of the same dimension following the first cutting edge, and even if it is more than that, the same function is achieved, but the overall length of the broach is increased and the cost is increased.

  Further, the material of the cutting edge of the finishing blade is a cemented carbide, and the broach tool is further provided with a hard coating on the surface (Claim 3). Thereby, it becomes more suitable for the finish broaching of a hard material.

  As described above, according to the present invention, there is provided a broaching tool for finishing a high-hardness material having a hardness of 45 to 65 HRC in which a number of cutting edges each having a large cutting edge dimension formed toward a finishing edge are provided in the longitudinal direction. In addition, the finishing blade is composed of two or more blades, and adjacent blades within the range of the maximum to minimum value of the broach finish dimension tolerance are made equal or smaller toward the back of the broach, and the final finish dimension blade is Because it is smaller than the first blade, the clearance angle of the cutting edge of the finishing blade is 1.1 ° or more and 2.0 ° or less, and it is a broach tool without a straight land, so a large cutting reaction force works Even when machining high-hardness materials with a hardness of 45 to 65 HRC, the flank of the cutting edge is less rubbed, and the wear of the cutting edge can be kept to a low level even at high speed cutting of 40 m / min or higher. Came. Further, the non-reground blade that is small in size and does not participate in cutting does not participate in cutting until it becomes a finished blade in the future, and is not affected by rubbing, so that the life of the broach can be extended (claim 1).

  Further, since the broaching tool has one or more cutting blades having the same dimensions as the first blade of the finishing blade, the processing dimensions of the workpiece in the initial state of broaching are stabilized. (Claim 2).

  Further, since the material of the cutting edge of the finishing blade is a cemented carbide and the surface is provided with a hard coating, it is more suitable for finishing broaching of a hard material (Claim 3).

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a plan view of a broaching tool showing an embodiment of the present invention, FIG. 2 is a side view of a finishing blade showing an embodiment of the present invention, and FIG. 3 is an enlarged plan view of the finishing blade of the broaching tool of FIG. FIG. 4 is an enlarged side view of the finishing blade of FIG. As shown in FIG. 1, the broaching tool of the present invention has a cutting edge 2 arranged in the longitudinal direction of the main body 1 in order of the cutting edge 2 toward the rear of the broach in order to process a desired workpiece shape. . As shown in FIG. 2 and FIG. 3, the finishing blade 2 f has n final finishing dimension blades, (n−1) sets positioned ahead of the broach from the final finishing dimension blade n sets, and (n−1) An (n-2) group consisting of two blades located in front of the group and three groups having different broach dimensions were arranged in order. These three sets of finishing blades are the outer dimensions within the allowable range of the finished dimensions of the broach, and the target dimensions of the broach are φ17.980 for n, φ17.990 for (n-1), and (n-2) for n It is set to φ18.000, and is set higher as it is located forward. Further, the clearance angle θ of all the finishing blades 2f is constant at 1.1 °, and there is no straight land. The cutting edge material was a cemented carbide coated with a hard film, and the outer diameter of the spline with a hardness of 60 HRC was processed.

  As shown in FIG. 2, when the broach is new, only the (n-2) finishing blades are involved in cutting, and the (n-1) and n finishing blades exist as spare blades and are involved in cutting. do not do. At this time, since (n-2) sets of finishing blades are two, finishing dimensions are more stable than finishing with only one blade. Next, when the (n-2) finishing blades are worn after a certain number of broaching operations, the rake face 4 of the (n-2) finishing blades is reground to form a new cutting edge. As a result of the re-grinding, the rake face 4 is shaped as indicated by a dotted line 5 by grinding the rake face 4 so as to eliminate the worn portion as shown in FIG. At this time, since the (n-2) finishing blades are not provided with straight lands, the dimension of the (n-2) finishing blades is in a state in which the dimension is minus by w, and the workpiece is also w compared with before re-grinding. It will be left alone. In this way, the dimensions of the (n-2) finishing blades gradually decrease, but finally the external dimensions of the (n-2) finishing blades and the rear (n-1) finishing blades. Are the same. At this point, the (n-2) finishing blades are broached together with the (n-1) finishing blades. Also at this time, there are two or more cutting blades of the same size as the (n-2) sets of finishing blades, and the machining dimension becomes stable. Also at this time, the final finished dimension blade n sets do not participate in cutting and exist as spare blades.

  As the process progresses further and the (n-2) finishing blades and the (n-1) finishing blades are further worn and the dimensions are reduced by regrinding, the (n-2) and (n-1) The finishing blade has the same outer dimensions as the final finishing dimension blade n set, and the final finishing dimension blade n is involved in the cutting. Finally, n sets of final finishing dimension blades are worn and reground, and the broach life is reached when all the finishing edges 2f are below the workpiece finishing dimension tolerance. In the present embodiment, even if the wear of the finishing blade 2f progresses, the final finishing dimension blade n always has no straight land by re-grinding, and is cut with the finishing blade 2f having the optimum clearance angle θ. Thus, a workpiece having a hardness of 60 HRC could be processed stably. In addition, the life of the broaching tool could be extended by reducing the size of the finishing blade 2f toward the rear.

  In this embodiment, (n-2) sets of finishing blades are 2 blades, (n-1) sets of finishing blades, and final finished dimension blades n sets are each 1 blade. What is necessary is just 1 to 3 blades, not sticking to a combination. Even if the number of blades in each group is 4 or more, the same function is achieved, but the overall length of the broach becomes long. In addition, when priority is given to shortening the broach due to restrictions such as the broaching machine stroke, the overall length of the broach can be shortened while securing the machining dimensions by reducing the size of the finishing blade toward the back of the broach in units of one sheet. Needless to say, it can be done. In this embodiment, the broach tool for spline outer diameter machining is used as an example. However, the present invention can be applied to other shapes or broach tools for surface machining.

It is a top view of the broach tool which shows embodiment of this invention. It is a side view of the finishing blade which shows embodiment of this invention. It is an enlarged plan view of the finishing blade of the broach tool of FIG. FIG. 3 is an enlarged side view of the finishing blade of FIG. 2.

Explanation of symbols

1 Broach tool 2 Cutting edge 2f Finishing blade n Final finishing dimension Blade θ Clearance angle

Claims (3)

A broaching tool for finishing a high-hardness material having a hardness of 45 to 65 HRC in which a large number of cutting blades formed in order toward the finishing blade are provided in the longitudinal direction.
The finishing blade is composed of two or more blades, and adjacent blades within the range from the maximum value to the minimum value of the broach finish size tolerance are made equal or smaller toward the back of the broach, and the final finish size blade is A broaching tool characterized in that it is smaller than the first blade, the clearance angle of the cutting edge of the finishing blade is 1.1 ° to 2.0 °, and no straight land is provided.   The broaching tool according to claim 1, further comprising one or more cutting edges having the same dimensions as the first cutting edge of the finishing blade.   The broaching tool according to claim 1 or 2, wherein a material of the cutting edge of the finishing blade is a cemented carbide and further a hard coating is applied to the surface.