JPH07197760A - Lock pit - Google Patents

Abstract

PURPOSE:To prevent abnormal wear of alloy part of a tip or decrease in bit service life caused by early wear of the tip by making large the degree of freedom in design of arragement or sizes of blade body or water holes, while making the hole tip out of cemented carbide. CONSTITUTION:The whole of tip 2 is made of cemented carbide and a button- like blade body 5 is integrated with the plane of te tip 6 so as to project therefrom. At a core of the tip 2 a water hole base paret 9 is arranged, and a narrow water hole opening in the bit tip is branched from the tip. A threaded hole 12 is formed at the rear part of a base 3 of a steel cylinder, and a fitted recess 13 formed at the tip of the alloy 3 and the threaded hole 12 are communicated with each other through the water hole 15. The tip 2 and the alloy 3 are communicated with each other. The two 2, 3 are fixed under a state that afitting projection part 7 is fited into the recess 13 of the alloy 3. Striking force or thrust conveyed to the alloy 3 is tranmitted to a rear end face 7a of fitting projection paret of the tip 2 form a bottom face of fitting recess 13, and thus transmission of force is made efficiently so that overload is not applied to the alloy 3 and the tip 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rock bit used together with a rock drill for crushing rock.

[0002]

2. Description of the Related Art There are various types of lock bits which are attached to a rock drilling machine through a drilling rod and are used when a pilot hole for blasting is drilled in a rock mass. The conventionally known rock bit is a steel base metal with a blade (tip) made of cemented carbide implanted in it, and the blade has a sharp chisel (chisel type) or a round button. There are some buttons, but recently, many buttons have been used.

When a rock bit is drilled in a rock using this type of rock bit, only the base metal part of the bit head is worn out depending on the rock quality, and the cemented carbide tip is exposed to the tip. There was a problem of falling out. Also,
Abrasive rocks, which are highly abrasive, suffer from severe chip wear and short bit life.

[0004]

For rocks with severe wear of the tip, it is possible to extend the life of the bit by increasing the size of the tip, but with a bit having a small diameter, the size of the tip is If it is increased, the chips interfere with each other or the water holes, and the wall thickness of the base metal part becomes thin, and the strength decreases, so this method is limited. Therefore, an object of the present invention is to prevent abnormal wear of the base metal part of the head and reduction of the bit life due to early wear of the tip.

[0005]

In order to solve the above problems, the present invention employs the following configurations. That is, the lock bit according to the present invention has a projection-shaped blade that projects forward at the tip, and a head made entirely of cemented carbide with a fitting portion formed at the rear, and a tip at the tip. A steel base metal having a fitting part for fitting with the fitting part of the head part, and a fitting part for the punched rod formed at the rear part, the fitting part on the head side and the base metal side. It is characterized in that they are joined and integrated by being fitted and fixed to each other by the fitting portion of.

[0006]

In this lock bit, since the entire head is made of a cemented carbide having excellent wear resistance, abnormal wear of the head base metal portion in the conventional bit is prevented. Further, even if the blade body is enlarged, since the entire head is made of cemented carbide, there is no problem of interference between the blade body and water holes, and the strength does not decrease.

[0007]

Embodiments of the present invention shown in the drawings will be described below. The lock bit 1 is formed by connecting a head 2 and a base metal 3 integrally.

The head 2 is entirely made of cemented carbide, and is usually made of tungsten carbide (WC) containing 6 to 8% by weight of cobalt. Button-shaped blades 5, whose tip is formed as a spherical surface, are integrally formed at the tip of the head made of cemented carbide so as to project from the head plane 6. Further, a cylindrical fitting protrusion 7 having a small diameter is formed at the rear end of the head.

A water hole base portion 9 that opens rearward is provided in the core portion of the head, and three thin water holes that open to the tip end portion of the bit are branched from the tip end portion thereof. Further, large and small milling grooves 10, ... Are formed on the side surface of the head. The root of the fitting protrusion 7 of the head has a small radius R.

The base metal 3 is formed as a steel cylindrical body, and is provided with a screw hole 12 which opens rearward at the rear portion. A circular fitting recess 13 into which the fitting protrusion of the head is fitted is formed at the tip of the base metal. Then, the water hole 15 in which the screw hole 12 and the fitting recess 13 are formed in the central portion
Are in communication with each other.

The head 2 and the base metal 3 are fixed in a state where the fitting protrusion 7 on the head side is fitted into the fitting recess 13 of the base metal 3. As the fixing method, shrink fitting, brazing or the like is adopted. In this fitted and fixed state, there is a slight gap t between the end surface 2a of the head and the end surface 3a of the base metal, and the impact and thrust transmitted from the rock drill to the base metal through the drill rod are:
It is transmitted from the fitting recess bottom surface 13a of the base metal to the fitting projection rear end surface 7a of the head. Therefore, the force is effectively transmitted, and the base metal, the head, etc. are not forced. In the illustrated example, the fitting portion on the head side is formed as a projecting portion and is fitted into the recess on the base metal side, but conversely, a fitting recess is provided on the head side to project on the base metal side. The part may be fitted to this.

(Results of Drilling Test) A button bit (diameter 45 mm) having the shape shown in the figure was prototyped and a drilling test was actually conducted. The results are as follows. That is, when the rock quality is weathered granite, only the base metal part is easily worn, but the conventional isomorphic bit has a tip of 300 m and the tip has fallen out, and the product has reached the end of its life. At 900 m, it became a life due to wear of the base metal screw part.

Further, when the rock quality is abradable silica, the conventional product has a life of 70 m due to chipage wear, whereas the product of the present invention has a life of 180 m due to chipage wear. . In this case, the base metal was not so worn.

[0014]

As is clear from the above description, the lock bit according to the present invention has the entire head portion made of cemented carbide, so that the base metal of the head as seen in the conventional bits is used. Abnormal wear does not occur in the part, and the degree of freedom in designing the dimensions and arrangement of the blade and water holes is large, so it is possible to deal with rocks with abundant wear by making the blade sufficiently large. It became so.

[Brief description of drawings]

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

FIG. 2 is a vertical cross-sectional view taken along the line X-O-Y.

FIG. 3 is a VOW sectional view of the head.

FIG. 4 is a vertical sectional view of a base metal.

[Explanation of symbols]

 1 Lock Bit 2 Head 3 Base Metal 5 Blade 7 Fitting Projection 12 Screw Hole 13 Fitting Recess

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kenji Okada 26-5 Ikeda Nishimachi, Neyagawa City, Osaka Prefecture Toho Metal Co., Ltd. Neyagawa Factory

Claims (1)

[Claims] 1. A head made entirely of cemented carbide with a protruding blade body protruding forward at the tip and a fitting portion formed at the rear, and a fitting of the head at the tip. A steel base metal having a fitting part that fits with the mating part and a fitting part for the punched rod at the rear part is formed by the fitting part on the head side and the fitting part on the base metal side. A lock bit characterized by being integrated by being fitted and fixed to each other.