JP2002137118A - Carbide broach - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a carbide broach capable of preventing chipping of a cemented carbide tip, providing a grip part with tenacity, reducing cost, and facilitating broach machining of a very hard material. SOLUTION: In the inner face broach 1 in which many cutting edges are arranged according to the order of dimension, a main body 2 having a grip part 11 has a barlike extension part 17 in a cylindrical rear end part 16, a hollow cylindrical or ringlike assembly body 3 is fitted and fixed to the extension part, the main body is formed by alloy steel, and the assembly body is formed by sintering a cutting edge 32 at outer periphery by a cemented carbide material integrally. A guide part 14 extending in the longitudinal direction to fit in a machining groove provided in a workpiece is provided in the main body. A guide part 34 on an assembly body side is provided in the longitudinal direction in the same phase and shape as the guide part. A trough diameter 35 of the cutting edge of the assembly body is fitted in an inside diameter not machine of the workpiece with a slight clearance to perform blade smoothing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a broach having a plurality of cutting blades arranged in an axial direction on an outer periphery of a main body, and more particularly to a carbide broach whose cutting blade is made of a hard metal. Further, the present invention relates to a carbide broach suitable for processing a material having a hardness of, for example, Rockwell hardness of 50 HRC or more after quenching.

[0002]

2. Description of the Related Art In conventional broaching, a workpiece (work) having a hardness of 20 to 30 HRC (Rockwell hardness C scale: the same applies hereinafter) is performed. For this reason, many processed products are subjected to a heat treatment for increasing hardness after broaching. For example, in a transmission part of an automobile, an involute spline hole is broached, and then the involute spline portion is carburized and quenched. At this time, the hardness of the quenched part is 60 HRC or more, and the carburizing depth is about 1 mm. However, since heat treatment distortion occurs when carburizing and quenching, the target shape is determined in advance in consideration of deformation during heat treatment, and the workpiece before quenching is processed. However, because the amount of deformation is unstable, for example, the accuracy (diameter,
Tooth trace, pitch, etc.) may not be in the target shape.

[0003]

Therefore, it is desired to perform a more accurate broaching after quenching.
With a broach using a conventional high-speed tool steel material for its cutting blade, it is not possible to machine a hardened material such as a workpiece after heat treatment. The service life becomes extremely short and is not practical. Also,
Vibration broaching is performed by applying micro-vibration to the super-abrasive electrodeposited broach on which diamond has been electrodeposited while applying micro-vibration, but the machining allowance is limited, the mechanical structure is complicated, and the processing speed is high. It is also low and not generalized. In addition, although there are many workpieces with a heat treatment distortion of 0.07 mm or more, the current allowance for vibration broaching is 0.07 m in diameter.
m or less, there are many parts that cannot completely remove the heat treatment distortion, and the processing efficiency is poor.

[0004] On the other hand, since the cutting performance can be improved by using a cutting edge made of cemented carbide, there is a type in which a cemented carbide tip is brazed to the outer periphery of a broach and arranged by a wedge clamp or the like. However, when broaching a hard material after heat treatment using these carbide broaches, there is a problem that chips are likely to be missing. In addition, for example, a carbide broach having an integrated cutting edge for preventing chipping is also difficult to manufacture and is expensive, has a large weight, and a pull broach has a problem that the toughness of a grip portion is weak.

[0005] The object of the present invention is to solve the above problems.
An object of the present invention is to provide a carbide broach capable of easily manufacturing a carbide broach having no chipping, securing toughness of a grip portion, and reducing costs. Another object of the present invention is to provide a super hard broach which can be easily broached by hardening or hard material having a high hardness by heat treatment or the like.

[0006]

According to the present invention, in a broach having an inner surface in which a number of cutting blades each having a grip portion are arranged in dimensional order, a main body having the grip portion has a rod-shaped extending portion opposite to the grip portion. Having at least one hollow cylindrical or ring-shaped assembly fitted and fixed to the extension portion,
The main body is formed of alloy steel, and at least one of the assemblies has a cemented carbide broach in which a part or all of the plurality of cutting edges are integrally sintered with the assembly with a cemented carbide material. The above-mentioned problem was solved by providing.

More specifically, a portion comprising a cemented carbide assembly integrally formed by sintering a cylindrical or ring-shaped cemented carbide having a cutting edge on the outer periphery and a portion having a grip portion made of tough alloy steel Are assembled as a single broach, so there is no problem of slipping or breakage of the gripping portion like a hard metal with low toughness. Further, since the cutting edge portion made of a cemented carbide material is integrally sintered with the assembly, it does not drop. The alloy steel is, for example, tool steel, bearing steel, or the like, and high-speed tool steel generally used for broaches is preferable. Also, in conventional helical broaches and the like, there is a member that is provided with a cutting edge provided on the outer periphery of the cylindrical shape behind the rough finishing portion, but the material of the cutting blade is the same as the rough blade and the finishing blade, It is separated to prevent interference during cutting edge grinding, etc., and has a different purpose from the present invention.

If the workpiece is not high in hardness, the machining conditions may be changed by using high speed tool steel for the main body, providing a rough cut portion on the main body side, and providing an assembly of cemented carbide material in the finished portion, for example. it can. However, broaching with a high hardness after quenching the workpiece is insufficient with alloy tool steel. Therefore, in the invention of claim 2, the main body does not have a cutting blade between the grip portion and the extension portion, and extends in the longitudinal direction so as to be fittable in a pre-machining groove provided in the workpiece. A guide portion is provided, and the cutting blade is provided only in an assembly of a cemented carbide material, and is broached with a cutting blade of a cemented carbide material.

That is, on the main body side, the guide portion is fitted into the pre-machining groove of the workpiece, and the phase of the workpiece and the broach are matched to perform positioning automatically. Furthermore, in the third aspect, the assembly-side guide portion is provided in the longitudinal direction in the same phase and the same shape as the guide portion at the front portion of the cutting edge of the assembly, so that the positioning is reliably performed before reaching the cutting edge. In the processing of a high-hardness material, it is preferable to perform the broaching speed of the cutting blade at a high speed of 40 m / min or more. For this reason, both guide portions also serve as a run-up section for increasing the cutting speed. Further, it is preferable that the length of the guide portion is long.

[0010] Further, in processing a hard material, it is desired to position the workpiece and the carbide broach as reliably as possible in order to ensure accuracy. In view of this, in the invention of claim 4, the valley diameter of the cutting blade of the assembly is fitted with a small gap to the inner diameter of the workpiece which is not machined, so that the blade is killed. As a result, the inner diameter of the workpiece and the valley diameter of the cutting blade of the assembly are firmly fitted, so that reliable positioning can be performed.

[0011]

Embodiments of the present invention will be described. 1 (a) is a side view of a carbide broach showing an embodiment of the present invention, with a part cut away, FIG. 1 (b) is a sectional view taken along the line CC, and FIG. 1 (c) is a sectional view taken along the line BB. (D) is the same AA
FIG. 2E is a side view of the main body 2 shown in FIG. 1, FIG. 2B is a side view of the main body 2 described in FIG. 1, FIG. c) is a sectional view taken along the line EE, (d) is a sectional view taken along the line DD, (e) is a view of the rear grip portion viewed from below, and (a) of FIG. A side view in which a part of the assembly 3 is cut away, (b) is a front view seen from the left side, (c)
FIG. 2 is a sectional view taken along the line GG of FIG. 1, and FIG. The carbide broach 1 shown in FIG. 1 is for processing spline grooves of a spline having a width of 8 mm and four spline grooves, and the material of the workpiece is heat-treated by SCM415. The machined portion is only the outer diameter of the spline groove.
mm, that is, 0.1 mm on one side. As shown in FIGS. 1 and 2, the main body 2 of the carbide broach 1 is manufactured using a high-speed tool steel material, and a grip portion 11 for pulling out the broach for forming a broach is formed at one end. It has a cylindrical portion 12 having an outer diameter slightly smaller than the minimum inner diameter of the workpiece. Cylindrical part 12 and grip part 11
A tapered portion 13 is provided between them. On the outer periphery of the cylindrical portion 12, four guide portions 14 are provided in the longitudinal direction that can be fitted into spline grooves of the workpiece. The guide portion 14 is a gradually increasing portion 1 whose width and height are gradually increased on the grip portion side.
5 are provided to facilitate the fitting and positioning in the spline grooves of the workpiece. On the side opposite to the gripping portion of the cylindrical portion 12,
That is, a rod-like extension 17 extends from the right end face (cylindrical rear end) 16 in the drawing, and the rear grip 1 is attached to the tip of the extension.
8 are provided. Adjusting portion 19, lock nut fitting portion 20, locking groove 2 toward the left from rear grip portion 18
1 are provided in order. As shown in FIGS. 1 and 2, two-sided widths 22 a and 22 b sandwich the extension 17 of the cylindrical rear end 16.
Are provided.

As shown in FIGS. 1 to 3, a hollow cylindrical assembly 3 is provided between a cylindrical rear end 16 of the main body 2 and the lock nut 4.
Is pinched. The hollow hole 31 of the assembly 3 is
The cutting edge 32 is provided on the outer periphery so that the cutting edge height is sequentially increased, and is integrally sintered with a cemented carbide material. One end of the assembly 3 has a flat width 33 on the left side as viewed in the figure.
a, 33b are formed, and the convex portion 2 of the main body 2 is formed.
2 and a drive flat is formed by the concave portion 33 and the convex portion 22 to prevent the main body 2 and the assembly 3 from being displaced in the rotational direction. Further, on the outer periphery of the concave portion 33 side of the assembly 3, four assembly side guide portions 34 having the same phase, the same size, and the same shape as the guide portion 14 of the main body 2 are provided in the longitudinal direction. Both sides of the assembly guide 34 are slightly tapered. The valley diameter portion 35 without a cutting edge shown in FIG. 3 performs blade cutting and is fitted to an already machined prepared hole portion of a workpiece. Reference numeral 36 denotes an escape portion.

The assembly 3 is inserted from the tip of the extension 17,
The extension portion 17 and the hollow hole 31 are fitted to the projection portion 22 and the recess portion 33 so as to coincide with the guide portion 14 and the assembly-side guide portion 34,
The lock nut 4 is brought into contact with the rear end (the right end in the figure) 37 of the assembly, and the female screw 41 which is obliquely opened in the lock nut is provided.
The assembly 3 is sandwiched and fixed so that a stop bolt 42 is screwed to the end, and the tip 42 a of the stop 3 is brought into contact with the stop groove 21 so as to urge the cylindrical rear end 16 of the main body 2. With this configuration, the grip portion has a tough tough carbide broach while having a carbide cutting blade. Further, the guide section 14, the assembly-side guide section 34,
The positioning of the workpiece and the cutting blade 32 of the assembly 3 is reliably performed by the blade killing unit 35, and highly accurate broaching can be realized.

As shown in FIG. 3D, in order to increase the cutting edge strength, the rake angle of the cutting edge of the cemented carbide assembly is set to a negative angle, and its range is 0 ° to −30. ° is preferred. Further, the clearance angle is preferably set to 1 to 2 °. further,
The cutting blade may be coated with a hard coating (TiAlN, TiCN, etc.). In the case of carbide broaching, the cutting speed is set to 40 m in order to absorb the heat generated during shearing into the chips.
/ Min or more is preferable. The length of the guide portion is preferably longer, but in the embodiment, the length of the cylindrical portion is 60 m.
m, 50 mm from the end face on the concave side of the assembly to the first cutting edge. The positioning in the rotational direction is performed by fitting two uneven widths in view of the strength of the cemented carbide material, but other positioning fitting methods such as knock pins and spring pins may be used.

[0015]

According to the present invention, the part made of the cemented carbide assembly and the part having the grip part made of alloy steel are integrally assembled into a single broach, so that the grip part slips or breaks. In addition, it is possible to provide a carbide broach that can prevent cutting-off of the cutting blade, can reduce the cost, and can easily perform broaching of a high-hardness material. Furthermore, high accuracy, long life, and high speed broaching have become possible even for those having complicated shapes in which the deformation of the heat treatment is difficult to predict and for those requiring high accuracy after the heat treatment. Furthermore, since the cutting edge of the cemented carbide may be replaced by a cylindrical or ring-shaped assembly, replacement when the cutting edge is worn is simple, easy, and economical.

On the main body side, the guide portion and the guide portion on the assembly side are fitted to the lower machining shape, which is the machining groove of the workpiece, so that the workpiece and the broach can be positioned, so that high-precision machining becomes possible. Was. Furthermore, the valley diameter of the cutting edge of the assembly is fitted to the inner diameter of the workpiece with a small gap, and the blade is killed, whereby the inner diameter of the workpiece and the valley diameter of the cutting edge of the assembly are firmly fitted. As a result, it is possible to obtain an effect such as reliable positioning.

[Brief description of the drawings]

FIG. 1A is a side view of an embodiment of the present invention, in which a part of a carbide broach is cut away, and FIG. 1B is a CC view of FIG.
(C) is a cross-sectional view taken along line BB of (a), (d) is a cross-sectional view taken along line AA of (a), and (e) is a rear grip portion of (a) viewed from below. FIG.

FIG. 2A is a side view of the main body 2 shown in FIG. 1, and FIG.
(A) is a sectional view taken along the line FF, (c) is a sectional view taken along the line EE of (a), (d) is a sectional view taken along the line DD of (a), and (e) is a sectional view of (a). It is the figure which looked at the rear grip part from the lower side.

3A is a side view in which a part of the assembly 3 shown in FIG. 1 is cut away, FIG. 3B is a front view of FIG.
(C) is a sectional view taken along line GG of (a), and (d) is a detailed enlarged view of (a) a blade shape.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Carbide broach 2 Main body 3 Assembly 11 Gripping part 12 Cylindrical part 14 Guide part 16 Cylindrical rear end part 17 Extension part 31 Hollow hole 32 Cutting blade 34 Assembly side guide part 35 Valley diameter part (cutting part)

Claims (4)

[Claims] 1. An inner surface broach having a plurality of cutting blades having a grip portion arranged in a dimension order, wherein the main body having the grip portion has a rod-shaped extending portion on the opposite side of the grip portion. 1 hollow cylindrical or ring-shaped assembly
The main body is formed of alloy steel, and at least one of the plurality of cutting edges is partially or entirely formed of a cemented carbide material on the outer periphery and is integrally sintered with the assembly. Carbide broach characterized by being made. 2. The apparatus according to claim 1, wherein the main body does not have a cutting edge between the grip portion and the extension portion, and has a guide portion extending in a longitudinal direction so as to fit into a pre-machining groove provided in the workpiece. 2. A carbide broach according to claim 1, wherein said cutting edge is provided only on an assembly of a cemented carbide material. 3. The assembly according to claim 2, wherein an assembly-side guide portion is provided in the longitudinal direction in the same phase as and in the same shape as the guide portion at a front portion of the cutting blade of the assembly according to claim 2. Hard brooch. 4. The cutting blade according to claim 3, wherein the valley diameter of the cutting blade is fitted to the inner diameter of the workpiece which is not machined with a slight gap to kill the blade.
The described carbide brooch.