JP2015188942A - Broach - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a broach free from causing chip packing in a cutting blade positioned on a broach body rear end side across a body reception groove, even when the body reception groove for supporting a broach body is formed on a cutting blade part.SOLUTION: A cutting blade part 4 where a plurality of cutting blades 5 are projected and arranged in the longitudinal direction of a broach body 1 is formed on the outer periphery of the broach body 1 in an axial shape. The cutting blade part 4 is formed with a body reception groove 7 between the two cutting blades 5 adjacent in the longitudinal direction of the broach body 1. In the two cutting blades 5 across the body reception groove, a projection amount to the broach body 1 outer peripheral side of the cutting blade 5 positioned at the rear end side of the broach body 1 is equal to or less than a projection amount to the broach body 1 outer peripheral side of the cutting blade 5 positioned at the tip end side of the broach body 1.

Description

  The present invention relates to a broach used for broaching of an internal gear or the like, in which a plurality of cutting blades protrude from the outer periphery of a shaft-shaped broach body to form a cutting blade portion disposed in the longitudinal direction of the broach body. .

  As such a broach, for example, in Patent Document 1, a plurality of rows of cutting blades are integrated with the broach body on the outer periphery of a long shaft-shaped broach body having a tension part and a support part (gripping part) at both ends. A helical broach formed in a spiral shape is disclosed. Here, when manufacturing such a long broach, if you try to process the cutting blade etc. by supporting the grip part at both ends of the broach body and placing the broach body horizontally, There is a possibility that bending in the center portion makes it difficult to perform processing with high accuracy.

  In view of this, Patent Document 1 describes that a shaker groove for supporting the broach body is formed at a substantially central portion in the longitudinal direction of the broach body. Therefore, in such a broach described in Patent Document 1, for example, a deflection jig is fitted in the groove to support the broach main body in the center in the longitudinal direction, thereby preventing the broach main body from being bent. This makes it possible to machine cutting blades and the like with high accuracy.

JP 2002-113614 A

  By the way, the central portion in the longitudinal direction of the broach body is usually a cutting blade portion in which a row of cutting blades as described above is formed, and when forming a shake receiving groove, so as not to interfere with the cutting blade, A groove must be formed between two longitudinally adjacent cutting edges. However, when a groove is formed between the cutting blades in this way, the cutting blade located on the rear end side of the broach body, that is, the broach body, of the two cutting blades between the grooves, is inserted into the pilot hole of the workpiece. There is a possibility that chips generated by the cutting blade located on the rear side in the insertion direction may be caught in the groove and cause clogging.

  The present invention has been made under such a background. Even if the main body receiving groove for supporting the broach main body as described above is formed in the cutting edge portion, the rear end of the broach main body is interposed between the main body receiving grooves. An object of the present invention is to provide a broach that does not cause chip clogging in a cutting blade located on the side.

  In order to solve the above-described problems and achieve such an object, the present invention provides a cutting blade in which a plurality of cutting blades are projected on the outer periphery of a shaft-shaped broach body and arranged in the longitudinal direction of the broach body. A main body receiving groove is formed between the two cutting blades adjacent in the longitudinal direction, and the two cutting edges sandwiching the main body receiving groove are formed in the cutting edge portion. Of the blades, the amount of protrusion of the cutting blade located on the rear end side of the broach body to the outer peripheral side of the broach body is less than the amount of protrusion of the cutting blade located on the tip side of the broach body to the outer peripheral side of the broach body. It is said that it is said.

  In the broach configured as described above, the cutting amount of the cutting blade positioned on the rear end side of the broach body among the two cutting blades sandwiching the main body receiving groove is the cutting blade positioned on the front end side of the broach main body. The cutting edge located on the rear end side of the broach main body is not cut into the workpiece. Therefore, no chips are generated by the cutting edge on the rear end side, and the generated chips do not clog.

  That is, according to the broach having the above-described configuration, the work surface of the workpiece is damaged by chip clogging during processing while processing the cutting blade or the like with high accuracy by supporting the broach main body by the main body receiving groove when manufacturing the broach. Or an increase in cutting resistance can be prevented. On the other hand, the cutting edge is formed on the rear end side of the cutting blade located on the front end side of the broach body with the main body receiving groove therebetween, although the protruding amount is not more than the cutting edge on the front end side. Therefore, smooth broaching can be performed by guiding the broach body with the cutting edge on the rear end side.

  In addition, in order to sufficiently ensure the guide performance by the cutting edge on the rear end side, the difference in the protruding amount of the two cutting blades between the main body receiving grooves to the outer peripheral side of the broach body is 10 μm or less. It is desirable to be done. In other words, when the difference in the protruding amount exceeds 10 μm, the cutting edge on the rear end side retreats too much toward the inner peripheral side of the broach body with respect to the cutting edge on the front end side, thereby ensuring sufficient guide performance. There is a risk that it will not be possible.

  As described above, according to the present invention, even if the main body receiving groove is formed in the cutting edge portion in order to form the cutting blade or the like with high accuracy, the main body receiving groove may cause chip clogging during broaching. It is possible to prevent deterioration of the work surface accuracy of the workpiece and increase in cutting resistance, and ensure smooth and stable broaching by ensuring the guide property of the broach body with the cutting edge on the rear end side of the body receiving groove Can do.

It is a side view which shows one Embodiment of the broach of this invention. It is the enlarged view seen along the spiral of the cutting blade row | line | column which shows the main body receiving groove periphery of embodiment shown in FIG.

  1 and 2 show an embodiment of the present invention. In the present embodiment, the broach main body 1 is formed in a long shaft-like substantially multi-stage cylindrical shape centering on the axis O as shown in FIG. 1 by a hard material such as high-speed tool steel, and the tip ( A front grip portion 2 is formed on the left side portion in FIG. 1, and a rear grip portion 3 is formed on the rear end portion (right side portion in FIG. 1). 4 is formed.

  A plurality of cutting blades 5 protruding from the outer peripheral surface 1 </ b> A of the broach main body 1 are formed integrally with the broach main body 1 in the cutting blade portion 4. In the present embodiment, these cutting blades 5 are spiral cutting blade rows that are twisted around the axis O with a gap from the front end side to the rear end side in the axis O direction (longitudinal direction of the broach body 1). A plurality of such cutting blade rows are formed at intervals in the circumferential direction. That is, the broach of this embodiment is an integrated helical broach, and a blade groove 6 is formed between the cutting blades 5 arranged in each cutting blade row, and the blade groove 6 is formed as shown in FIG. A plurality of cutting blade rows are formed in a twisted groove shape extending in a direction intersecting with the spiral formed by each cutting blade row.

  Such a cutting blade 5 is formed so that the amount of protrusion of the cutting blade 5 toward the outer peripheral side of the broach body 1 increases toward the rear end side in the axis O direction at the front end portion of the cutting blade portion 4. Broaching is performed so that the groove depth gradually increases. For example, when the workpiece is an internal gear or the like and a certain degree of accuracy is required for the tooth surface, the cutting amount of the cutting blade 5 toward the outer peripheral side of the broach body 1 is increased after the amount of protrusion is increased. A finishing portion in which the blade thickness of the blade 5 in the circumferential direction of the broach body gradually increases is provided on the rear end side of the cutting blade portion 4, and the tooth surface is finished so that the width of the gear tooth groove is widened. Sometimes.

  Further, the cutting edge portion 4 of the broach body 1 is formed with a body receiving groove 7 on an outer peripheral surface 1A between two cutting edges 5 adjacent to each other in the axis O direction (longitudinal direction). As shown in FIG. 2, the main body receiving groove 7 is formed such that a cross section along the axis O opens in a “U” shape on the outer peripheral side, and the distance from the axis O of the bottom surface facing the outer peripheral side. The (radius) is constant, and is formed at a substantially central portion of the cutting edge portion 4 in the axis O direction.

  Here, the main body receiving groove 7 is formed on a plane perpendicular to the axis O as shown in FIG. 1 in the portion of the blade groove 6 between the two cutting blades 5 with the interval between the cutting blade rows. The annular groove which is located and makes one round of the outer peripheral surface 1A of the broach main body 1 in the cutting edge part 4 may be used. Further, in the broach in which the blade groove 6 is twisted as in the present embodiment, a twist groove along the twist of the blade groove 6 may be used.

  Of the two cutting blades 5 in each of the cutting blade rows sandwiching the main body receiving groove 7, the amount of protrusion of the cutting blade 5 located on the rear end side of the broach main body 1 to the outer peripheral side of the broach main body 1, that is, A radius from the axis O to the outer peripheral end of the cutting blade 5 is set to be equal to or less than a protruding amount of the cutting blade 5 located on the distal end side of the broach main body 1 to the outer peripheral side of the broach main body 1. In the present embodiment, the difference between the protruding amounts of the cutting blades 5 is 0, that is, the protruding amounts of the two cutting blades 5 with the main body receiving groove 7 interposed therebetween are equal to each other.

  The broach constructed in this way has the front grip part 2 on the front end side inserted into the prepared hole of the work placed on the broaching machine, and the front and rear grip parts 2 and 3 are supported by the broaching machine. Then, the tooth gaps and the like as described above are formed on the inner peripheral surface of the prepared hole by the cutting blade 5 of the cutting blade portion 4 while being inserted into the prepared hole. At this time, chips are generated in the cutting blade 5 in which the amount of protrusion from the outer peripheral surface 1A of the broach body 1 gradually increases, and this chip is accommodated in the blade groove 6 formed on the tip side of each cutting blade 5 and When the cutting edge 5 comes out of the workpiece, it is discharged.

  However, the cutting blade 5 located on the rear end side of the broach main body 1 of the main body receiving groove 7 has a cutting edge 5 adjacent to the front end side of the broach main body 1 of the cutting blade row having the same protruding amount via the main body receiving groove 7. Since it is made into the protrusion amount or less, it is not cut into a workpiece | work and a chip is not produced | generated. Therefore, such chips do not get caught in the main body receiving groove 7 and become clogged, so that the processing surface of the workpiece is not damaged and the cutting resistance is not increased.

  Further, when manufacturing such a broach, the broach main body 1 is placed horizontally, and the front and rear gripping portions 2 and 3 at both ends and the main body receiving groove 7 at the substantially central portion in the longitudinal direction are supported by a jig or the like. Thus, it is possible to prevent the broach body 1 from being bent. Therefore, for example, even when the cutting edge portion 4 is formed, each cutting edge 5 can be formed with high accuracy, and thus high-precision broaching can be performed.

  Further, a cutting blade 5 is formed on the rear end side of the broach main body 1 of the main body receiving groove 7 although no chips are generated. The cutting edge 5 is located on the front end side of the broach main body 1 of the main body receiving groove 7. The broach main body 1 can be guided by making sliding contact with a groove formed in the workpiece by the cutting blade 5. In particular, in this embodiment, since the said protrusion amount of the cutting blade 5 which has the main body receiving groove 7 in between is mutually equal, higher guide property can be acquired.

  Therefore, for example, in the helical broach as in this embodiment, when the main body receiving groove 7 is an annular groove located on a plane orthogonal to the axis O as shown in FIG. Even when the interval between the cutting edges 5 at the front and rear ends of the main body receiving groove 7 is increased in order to form the groove 7, the broach main body 1 can be stably fed to the front end side for accurate broaching. it can.

  However, if the difference in the protruding amount of the two cutting blades 5 between the main body receiving grooves 7 to the outer peripheral side of the broach main body 1 is too large, the cutting blades on the rear end side of the broach main body 1 out of these cutting blades 5. There is a possibility that the guide 5 cannot be ensured without sufficiently sliding in contact with the groove formed by the cutting edge 5 on the front end side because the 5 is retracted too much. For this reason, it is desirable that the difference in the protrusion amount is 10 μm or less.

  In the present embodiment, the case where the present invention is applied to a broach in which the blade groove 6 has a twisted groove shape like a helical broach has been described. However, the blade groove is located on a plane perpendicular to the axis of the broach body. It is also possible to apply to a broach with a right-angle groove.

DESCRIPTION OF SYMBOLS 1 Brooch body 4 Cutting edge part 5 Cutting blade 6 Blade groove 7 Body receiving groove O Axis of broach body 1

Claims (2)

  A plurality of cutting blades project from the outer periphery of the broach main body having an axial shape to form a cutting blade portion disposed in the longitudinal direction of the broach main body, and the cutting blade portion is adjacent to the longitudinal direction. A main body receiving groove is formed between the two cutting blades, and the outer periphery of the broach main body of the cutting blade located on the rear end side of the broach main body among the two cutting blades sandwiching the main body receiving groove The amount of protrusion to the side is equal to or less than the amount of protrusion of the cutting blade located on the distal end side of the broach body to the outer peripheral side of the broach body.   2. The broach according to claim 1, wherein a difference in protrusion amount of the two cutting blades between the main body receiving grooves to the outer peripheral side of the broach main body is 10 μm or less.

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