JPH07148729A - Diamond core bit - Google Patents

Abstract

PURPOSE:To respectively improve the rigidity, machinability, safety and the like by a method wherein compacts, each of which is made of diamond abrasive grains or the like and hot-glued to the tip of a body, are hot-glued to a base metal, which is made of a quenchable and temperable steel annulus, and, at the same time, the base metal is sealed to the body. CONSTITUTION:A diamond core bit is produced by hot-glueing a plurality of compacts 1, each of which is prepared by sintering diamond abrasive grains and metal powder, which are hot-glued at fixed intervals peripherally at the tip of a tubulaly formed body 3. In this case, the compacts l are hot-glued through joining parts 2 to a base metal 4, which is made of a quenchable and temperable steel annulus. Further, the base metal 4 and the body 3 are sealed through an anchorage 5 to each other. Thus, through the hot-glueing between the compact 1 and the base metal and simultaneously through the quenching of the base metal 4, the rigidity of the bet is enhanced and, at the same time, the deformations and bendings of the body 3 and of the compact 1 are prevented from occurring, resulting in improving the sticking properties to the material to be machined at machining and preventing time chipping-off and flying-apart of the compact from occurring so as to ensure excellent safety.

Description

Detailed Description of the Invention

[0001]

The present invention relates to concrete, brick,
The present invention relates to a diamond core bit used for drilling rocks, asphalt, etc.

[0002]

2. Description of the Related Art FIG. 6 is a side view of a conventional diamond core bit. In the figure, 1 is a diamond tip molded body, 2 is a joint between the molded body and the body 3, and 3 is a body. Conventionally, as shown in FIG. 6, the diamond core bit is formed by joining a plurality of arcuate shaped bodies to the tip of a tubular body 3 with a space therebetween. The diamond core bit is directly connected to a power source such as an electric tool and is used as a work material for drilling work such as concrete with reinforcing bars, bricks, rocks and asphalt. The diamond abrasive grains in the compact serve as a sharp edge during cutting, and fall off at any time during the cutting process,
The next new diamond grain comes out on the surface and continues the cutting. The molded body 1 is joined to the body 3 of a circular pipe of low carbon steel (carbon content of 0.25% by weight or less) directly at the tip by means of welding, welding or the like. It is a hexahedron with arcuate parts. Since this low carbon steel pipe is generally manufactured by extrusion molding or pultrusion molding, low carbon steel with little work hardening is used. The Vickers hardness of the low carbon steel pipe is Hv 150 to 250, and it is work hardened during the forming process of the steel pipe. The body of the low carbon steel pipe and the molded body are bonded together by using a silver roller or by locally melting them with a heating source such as a laser beam. The work-hardened steel pipe is softened by the heat effect at the time of joining, and its Vickers hardness is Hv120-1.
It is 70.

FIG. 7 is a partial sectional view of FIG.
And the joint portion 2 of the body 3 is formed. The body thickness t ₂ is smaller than the thickness t _{1 of the} molded body for facilitating the swarf, and the swarf is extruded from the inner and outer surfaces of the body due to the difference in the thickness.

[0004]

However, in the conventional diamond core bit, since the compact containing diamond abrasive grains is heat-bonded to the body of the low carbon steel pipe, the hardness is lowered due to the heat effect at the time of the bonding. , Its Vickers hardness is Hv 120 to 170, and it is easily deformed. When the punching operation is performed with a higher thrust, the body is not rigid, so that the body may be deformed or bent during cutting, and the molded body may be chipped or dropped due to the deformation of the tip of the body. In order to improve the cutting performance, the thickness of the compact is reduced to reduce the cutting resistance, and the thickness of the body is inevitably reduced accordingly, so the rigidity of the body is further reduced and the body is cut from the initial stage of cutting. Due to the deformation, the perforation work becomes difficult. Furthermore, since the strength of the joint portion due to bending is weak even when cutting with high thrust and high speed rotation, the diameter also increases with the deformation of the tip portion of the body, and further cutting becomes impossible. That is, the cutting conditions for heavy cutting are naturally limited.

An object of the present invention is to provide a diamond core bit which can maintain high machinability for a long time and is excellent in safety.

[0006]

In order to achieve the above object, the diamond core bit of the present invention comprises a plurality of compacts formed by firing diamond abrasive grains and metal powder at the tip of a tubular body in the circumferential direction. In a diamond core bit that is heat-bonded at a fixed interval, the molded body is heat-bonded to a base metal made of a steel circular tube capable of quenching and tempering, and further, the base metal and the body are fixed. Characterize.

[0007]

The diamond core bit of the present invention uses a base metal made of a steel circular tube that can be quenched and tempered between the body and the molded body, and heat-bonds the molded body to the base metal so that when the molded body is bonded, Gold is hardened to increase rigidity, deformation of the body and molded body against normal cutting and heavy cutting,
Bending can be prevented. Bonding is possible without lowering the bonding strength of the base metal of the thin molded body, and because it has high toughness and rigidity, there is no deformation or bending of the body, and the clinging property during continuous drilling work is good, and The cutting performance is constant and stable until the end of its life as a diamond core bit. Since the body deformation is extremely suppressed in this way, there is no problem with the impact load acting on the molded body during cutting, and the molded body is free from chipping and falling.

[0008]

Embodiments of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a side view of an embodiment of the diamond core bit of the present invention. FIG. 2 is a partial cross-sectional view of FIG. In FIGS. 1 and 2, 1 is a molded body, 2 is a joint portion, 3 is a body, 4 is a base metal made of a steel circular tube that can be quenched and tempered, and 5 is a fixed portion between the base metal and the body. A plurality of compacts 1 obtained by firing diamond abrasive grains and metal powder are joined to the tip of the base metal 4 at equal intervals in the circumferential direction. This base metal 4 is made of a steel pipe that can be hardened to have rigidity,
The steel circular pipe is structural alloy steel, carbon steel, carbon tool steel, alloy tool steel, high speed tool steel, martensitic stainless steel, or the like. In particular, when a carbon steel base metal is used, the quenchable carbon content is 0.25% by weight or more.

The first feature of the diamond core bit of the present invention is that a quenchable steel pipe is used in the base metal, so that when the molded body and the base metal are joined together, and when the molded body, the base metal and the body are joined together, When joining at the same time, it means quenching at the same time as the joining due to the heating at the joining. Then, by tempering at an appropriate temperature, toughness can be imparted and hardness can be adjusted. The Vickers hardness of the base metal is also Hv30.
Since the rigidity of the joint is increased to 0 or more, the deformation of the base metal and the body as well as the deformation of the molded body especially against heavy cutting,
Less bends. Further, even when the thickness of the compact is reduced to reduce the cutting resistance to improve the cutting efficiency, the diamond core bit itself can be prevented from being deformed because the rigidity of the base metal is maintained.

The second feature is that since the alloy having high strength and rigidity is used, the bending of the molded body and the body is eliminated, and the clinging property to the work material during the drilling work is improved.
High circularity of the molded body can be always maintained, and concrete with reinforcing bar
Even in a work material having a non-uniform composition such as a gutter, the bending in the drilling direction due to one-sided contact is eliminated, and stable cutting performance can be obtained until the final work. If the diamond core bit is accidentally dropped on the ground, the body will not be deformed.

A third feature is that since a base metal having high strength and high toughness is used, it is effective against uneven force acting on the molded body at the time of biting in the initial cutting, and deformation of the body is suppressed. At the same time, the molded body is free from chipping, falling off, and scattering, resulting in excellent safety.

A base made of a body of a low carbon steel pipe having a carbon content of 0.2% by weight, a molded body, and a circular pipe of carbon tool steel (JIS standard SK5) was prepared and set on a joining jig. For joining, use silver silver material (JIS standard BAg-4, melting temperature 66
0-780 ° C.) was applied to two places on the joint. The base metal was heated to 850 ° C. by high frequency heating and rapidly cooled, and then heated again to 400 ° C. by high frequency heating to perform tempering. The Vickers hardness of the base metal at that time is Hv470-50
It was 0, and both of the joints were good.

Next, application examples are shown in FIGS. 3, 4 and 5.
In FIG. 3, a quenching base metal is preliminarily provided with a joint groove in which the molded body is fitted and joined, and the base metal is quenched at the same time when the molded body, the base metal and the body are joined. Then, tempering treatment is performed so that a predetermined hardness is obtained. The joint strength of the molded body becomes higher, which is more effective for heavy cutting. 4 is shown in FIG.
The molded body is joined to a part of the joining groove of the base metal of high hardness and high strength manufactured in the same manner as the above, and the joining groove other than the joining portion is used as the chip discharging groove 6 to further discharge the chips. Easy and high cutting performance can be obtained.

FIG. 5 shows a diamond core bit manufactured in the same manner as in FIG. In order to provide the chip discharge groove 6 to the base metal of the circular pipe by post-processing, the base metal between the formed bodies was removed by machining or the like. As a result, the same result as in FIG. 4 was obtained.

After the molded body and the base metal have been joined, the body may be fixed to the body by screwing, shrinkage fitting, press fitting, etc., in addition to the attachment by a lot. Furthermore, the present invention is also effective as a small diameter bit, and one disc-shaped molded body with a groove can be joined to the body via a cylindrical base metal having high hardness and high strength. Further, when laser beam or electron beam welding, which has the least heat effect, is used, it is possible to join using a base metal which has already been quenched and tempered. In this case, the softening of the base metal is very small.

[0016]

According to the present invention, since the base metal made of a steel circular tube capable of quenching and tempering is used between the molded body and the body, the base metal is quenched when the molded body is heat-bonded to the base metal. The rigidity is improved, the deformation and bending of the body and the molded body can be prevented, and the safety is also excellent. The biting property during continuous drilling work is improved, and stable high cutting performance is achieved as a diamond core bit. It is stable until it runs out.

[Brief description of drawings]

FIG. 1 is a side view of an embodiment of a diamond core bit of the present invention.

FIG. 2 is a partial cross-sectional view of FIG.

FIG. 3 is a side view of an application example of the diamond core bit of the present invention.

FIG. 4 is a side view of an application example of the diamond core bit of the present invention.

FIG. 5 is a side view of an application example of the diamond core bit of the present invention.

FIG. 6 is a side view of a conventional diamond core bit.

FIG. 7 is a partial cross-sectional view of FIG.

[Explanation of symbols]

Reference numeral 1 is a molded body, 2 is a joint portion, 3 is a body, 4 is a base metal, 5 is a fixed portion, and 6 is a chip discharge groove.

Claims (1)

[Claims] 1. A diamond core bit in which a plurality of compacts obtained by firing diamond abrasive grains and metal powder are heat-bonded to each other at a fixed interval in the circumferential direction at the tip of a tubular body. A diamond core bit, characterized in that it is heat-bonded to a base metal made of a recyclable steel pipe, and the base metal and the body are fixed to each other.