JPH07299648A - Broach - Google Patents

Abstract

PURPOSE:To hold a front guide in a highly accurate concentric form in a prepared hole, and improve work accuracy of a work by forming a cross-sectional shape of the front guide in a polygon, setting this outside diameter almost equal to an inside diameter in the prepared hole of the work, and forming surfaces of the respective edges as a recess-projection surface. CONSTITUTION:In a broach 10, a spline hole forming cutting edge 12 is integrally formed on the outer periphery of a bar-shaped main body 11. A shank 14 is integrally formed in a lower end part of the main body 11. A pulling-out binding part 15 is arranged on the lower end of the shank 14, and a front guide 16 is arranged above the binding part 15. In this case, in the front guide 16, this cross-sectional shape is formed in a polygon, for example, a square, and this outside diameter is set in a diameter slightly smaller or equal to an inside diameter in a prepared hole 8 of a work 7. Surfaces on the respective edges 16a of the front guide 16 are formed as a recess-projection surface having a prescribed pitch in the axis direction, that is, as a waveform.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a broach for forming spline teeth, gear teeth and the like on the inner peripheral surface of an annular work.

[0002]

2. Description of the Related Art As a conventional technique, there is one shown in FIGS. In FIG. 3, reference numeral 1 denotes a broach for forming a spline hole, in which a large number of similar cutting edges 3 are axially arranged at a predetermined pitch on the outer periphery of a columnar main body 2, and the main body 2 has a lower portion (advancing side). It has a shank 4 at the end). Each cutting edge 3 is formed in a trapezoidal shape in a side view and is divided at a predetermined pitch in the circumferential direction, and is formed so that the tooth height gradually increases from the lower portion to the upper portion.

The shank 4 has a constricted portion 5 for pulling out at the lower end, and a front guide 6 on the upper portion of the constricted portion 5. The front guide 6 is formed to have a circular cross section, and its diameter is set to a predetermined gap C with respect to the prepared hole 8 of the work 7.
Is formed, that is, the front guide 6 is formed in a small diameter so that the front guide 6 smoothly fits into the pilot hole 8. Reference numeral 9 is a table on which the work 7 is placed.

[0004]

In the above-mentioned conventional apparatus, since the front guide 6 has a cylindrical shape, the front guide 6 can be smoothly inserted without biting into the lower hole 8 of the work 7. It is necessary to increase the gap C. However,
When the gap C becomes large, the front guide 6 is likely to be eccentric or vibrate with respect to the pilot hole 8 of the work 7 due to the load at the time of machining, and the large diameter (outer diameter) of the machined spline hole.
However, there is a defect that the runout, the end face runout, and the like occur. It is an object of the present invention to obtain a new broach that eliminates the above drawbacks.

[0005]

The present invention is configured as follows to achieve the above object. That is, a large number of similar cutting edges are arranged in the axial direction at a predetermined pitch on the outer periphery of a rod-shaped main body, a shank is provided at the forward end of the main body, and a front guide is provided at the base of the shank. In the broach, the cross-sectional shape of the front guide is made polygonal so that the outer diameter thereof is substantially equal to the diameter of the pilot hole of the work, and the surfaces of the ridges of the front guide are formed into uneven surfaces having a predetermined pitch in the axial direction. It is configured to do.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. In the drawings, FIG. 1 is a sectional view showing an embodiment of the present invention, and FIG. 2 is a II-II sectional view thereof. In FIG. 1, 1
Reference numeral 0 denotes a broach, which integrally forms a cutting edge 12 for forming a spline hole on the outer periphery of a rod-shaped main body 11. The cutting edge 12 has the same structure as the conventional one, and is divided into a trapezoidal shape in a side view and at a predetermined pitch in the circumferential direction, and the tooth length is gradually increased from the lower (advancing end) side to the upper side. Form.

A shank 14 is integrally formed at the lower end (advancing end) of the main body 11. The shank 14 has a constricted portion 15 for pulling out at the lower end, and a front guide 16 integrally on the upper portion of the constricted portion 15. Front guide 16
Has a square cross section, as shown in FIG.
The outer diameter D2 is slightly smaller than or equal to the inner diameter D1 of the pilot hole 8 of the work 7. Further, as shown in FIG. 1, the surface of each ridge 16a of the front guide 16 has an uneven surface with a predetermined pitch in the axial direction (vertical direction),
That is, it is formed into a waveform.

According to the above-described embodiment, the contact area between the front guide 16 and the pilot hole 8 of the work 7 becomes extremely small, and the surface of this contact portion, that is, the surface of each ridge 16a has a vertical wavy shape. Therefore, even if the gap between the front guide 16 and the pilot hole 8 of the workpiece 7 is significantly smaller than the conventional one, or the diameter D2 of the front guide 16 is slightly larger than the diameter D1 of the pilot hole 8. The front guide 16 can be smoothly inserted without biting into the lower hole 8.

By bringing the diameter D2 of the front portion guide closer to the diameter D1 of the lower hole 8, the front portion guide 16 is held in the lower hole 8 of the work 7 in a highly accurate concentric manner, and the front guide 16 is circumferentially oriented. The cutting edge 12 evenly contacts the circumferential portion of the pilot hole 8. As a result, a highly accurate spline hole without a large-diameter (outer diameter) runout and end face runout is machined. The cross-sectional shape of the front guide 16 may be triangular.

[0010]

As is apparent from the above description, according to the present invention, the cross-sectional shape of the front guide is made polygonal so that the outer diameter thereof is substantially equal to the diameter of the pilot hole of the work, and each of the front guides. Since the ridge surface is an uneven surface with a predetermined pitch in the axial direction, the front guide is held concentrically with the work pilot hole with high accuracy, and the machining accuracy of the work is improved, and the front guide It has the effect of preventing biting.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a cross-sectional view showing a conventional example.

4 is a sectional view taken along the line IV-IV in FIG.

[Explanation of Codes] 10 Brooch 11 Main Body 12 Cutting Edge 14 Shank 15 Constriction 16 Front Guide 16a Ridge D1 Internal Diameter of Pilot Hole D2 Outside Diameter of Front Guide

Claims (1)

[Claims] 1. A rod-shaped main body is provided with a large number of similar cutting edges arranged in the axial direction at a predetermined pitch in a dimensional order, a shank is provided at the forward end of the main body, and a front guide is provided at the base of the shank. In the broach provided, the cross-sectional shape of the front guide is made polygonal so that the outer diameter is substantially equal to the diameter of the pilot hole of the work, and the surfaces of the ridges of the front guide are arranged at a predetermined pitch in the axial direction. Brooch characterized by having an uneven surface.