JPS606310A - Manufacture of twist drill - Google Patents

Abstract

PURPOSE:To improve machinability by combining a starting material, brazing process, quenching process, and cutting process rationally and functionally, thus improving the working performance. CONSTITUTION:A blade body 6 made of sintered hard alloy is brazed at the top edge of a twist drill body 1, and the rand part 9 constituted of a torsional groove 7 and a margin 8 in pairs and a pair of top-edge cutting edges 10 are formed onto the blade body 6. Brazing is applied onto the truncated cutting surfaces 11 and 12 in V-figure form, and quenching is carried-out through air cooling. Then, the brazed part is cut and ground by a metal-bonded diamond grindstone. since the truncated cutting surfaces 11 and 12 are in V-figure form, stable brazing work is permitted.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a twist drill having a blade made of cemented carbide at its tip, and is particularly directed to improving its workability, quality, and cutting performance.

Conventionally, this type of drill and
The one shown in Japanese Patent No.-51516 is known.

However, this drill first mills a torsional groove on the drill body, then hardens it, then brazes it to the joint position of the blade body, and then forms the torsional groove on the blade body. It is ground continuously.

Therefore, it is sometimes difficult to accurately determine the joint position when brazing, and it is also difficult to set standards for the grinding position, resulting in poor workability.Furthermore, the finishing accuracy is not always good, resulting in unstable quality and cutting performance. there were.

For these reasons, there is a demand for the development of a method for manufacturing twist drills that has high workability and improves finishing accuracy related to quality and cutting performance.

The present invention has been made in view of the above-mentioned points, and includes a method for manufacturing a twist drill in which a blade body made of cemented carbide is brazed to the tip of the main body made of M-made material.
Brazing is a twist drill manufacturing method that rationally and functionally combines the hardening process and grinding process to improve workability and improve quality and cutting performance in relation to finishing accuracy. It provides:

An embodiment of the method for manufacturing a twist drill according to the present invention will be described below with reference to the drawings.

In Figures 1 and 2, (1) is a drill body made of silk, and a land portion (4) with a pair of twisted grooves (2) and a margin (3) is formed on the outer periphery of the drill body. , and a handle portion (5) is connected to the rear thereof.

In addition, a blade (6) made of cemented carbide is brazed to the tip of the main body (1), and this blade (6) has the following features:
A pair of twisted grooves (7), a land portion (9) with a margin (8), and a pair of tip cutting edge ridges are formed.

Therefore, the starting material for the main body and the blade (6) is a round bar material, as shown in Figures 3 and 4, which is a secondary material. Sometimes,
A protruding portion and a recessed portion each consisting of a single cut surface exhibiting a letter 7 are formed, and a seam is formed by joining the two. In this case, copper brazing, silver brazing, etc. are appropriately selected for brazing, and the drill body (1) is hardened by air cooling after brazing.

Therefore, the drill body (1) is SNCM8,5KH9
It is made of steel materials such as.

The brazed secondary material as shown in Figures 3 and 4 is then ground with a metal bond diamond grindstone, resulting in a pair of twisted grooves (2) (
7), land portion (4) with margin (3) (8)
(9) is formed. In this case, the apex angle of the joint between the blade (6) and the drill body (1) is located on the axial center line α1 of the helical grooves (2) and (7), and the cutting surface (iD ( 17J intersects on the margins (3) and (8) as shown in Fig. 5. This crosses the outer cutting edge (Lo) along the margins (3) and (8).
The chip margin (3) (
8) The brazing layer is designed to prevent the layer from being gouged 9 due to scratches on the top.

In the twist drill constructed by such a manufacturing process, firstly, brazing has the effect of stabilizing the work. This is because brazing sometimes does not have the torsion groove (2) on the drill body (1) that is conventionally seen, so the area at the beginning of the head becomes larger, and brazing is easier to work with and the result is more reliable. This is because it is also stable.

Second, brazing the blade (6) and the drill body (1) has the effect of improving strength. This is because brazing improves the fluidity of the brazing filler metal due to work stability and eliminates the occurrence of brazing breakage.

Third, because the torsion grooves (7 bar 2) of the blade body (6) and the drill body (1) are ground at the same time, finishing accuracy is improved, resulting in improved quality and improved cutting performance. It has the effect of This is because it is difficult to position the cutting surface (11) Qa and the torsion grooves (2) and (7) in the conventional type. This is because it is sufficient to consider positioning it on the axis center line (131) in the grooves (2) and (7).

As explained above, the present invention considers functional and rational combinations of each manufacturing process of the drill body and the blade body. 1. In particular, brazing from a starting material of a round bar material provides work stability and reliability. In addition, since simultaneous grinding is adopted for forming the torsion grooves on the main body and the blade body, the finish accuracy is good, and there is an advantage that it is possible to provide a twisted IJ) with improved quality and cutting performance.

[Brief explanation of the drawing]

Fig. 1 is a front view showing an embodiment of a twist drill obtained by the manufacturing method of the Risted IJ7 of the present invention, Fig. 2 is an enlarged bottom view, and Fig. 3 is a front view showing the relationship between secondary materials. , FIG. 4 is a partially side view thereof, and FIG. 5 is a partially enlarged front view showing the joint portion between the drill body and the blade body. (1)・・・Drill body (2X7)・・・・・・
・Twisted groove (3X81...Margin (6)...
...Blade body (l IXI 2+...Cut surface patent applicant Toshiba Tungaloy Corporation

Claims (1)

[Claims] A drill body (1) made of steel in which a land portion (4) having a pair of twisted grooves (2) and a margin (3) is formed, and a tip cutting edge ridge. aQ1 A blade body (6) made of cemented carbide in which a land portion (9) with a torsion groove (force and margin (8) is formed).
), in which the blade body (6) and the drill body (1) each use a round bar as a starting material, and the brazing is performed in the process as described above. The blade body (6) side is formed as a protruding part having a 7-shaped cutting surface Ql, and the drill body (1) side is formed as a recessed part having a 7-shaped cutting surface Ql. 17) In the hardening process of the main body (1), the brazing is hardened by air cooling during the process, and in the grinding process of the torsion grooves (2) and (7), the joints are simultaneously ground with a diamond grindstone and The apex part of is located on the east of the axis center line α in the torsion grooves (2) and (7),
A part of the cut surface αυα is the margin (3) (8).
A method for manufacturing a twist drill, characterized in that the twist drill is ground so as to intersect at the top.