JPH06212875A - Excavation tool - Google Patents

Abstract

PURPOSE: To prevent the abrasion of the main body of a tool for breaking or excavating by fixing a separately formed ring made of a harder material than the main body and an insert to a prescribed position of the main body in such a manner that the ring surrounds the main body section of the insert and covers the front face of the main body. CONSTITUTION: An insert 20 is inserted into the shaft hole 14 of the front section 12 of the main body 2 of a tool for breaking or excavating. Then a separately formed ring 30 made of a harder material than the main body 2 is attached to the front face of the main body 2 in a state where the ring 30 surrounds the insert 20. Then the ring 30 and insert 20 are fixed to the main body 2 by soldering. At the time of soldering the ring 30 and insert 20 to the main body 2, the early abrasion of the ring 30 is prevented by positioning the ring 30 and insert 20 in such a manner that the tangential line T connecting the external surface of the tapered chip 24 of the insert 20 with the outer periphery of the ring 30 is included in a virtual conical cell body E formed with respect to the major axis of the tool. Therefore, the tool can be manufactured inexpensively with a simple constitution and, at the same time, the service life of the tool can be prolonged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called drilling tool for breaking or excavating minerals and the like, which is a tool body, typically a tool body protruding from a hole opened at a tapered front end of a steel tool body. A tool comprising a working insert of a harder material.

[0002]

BACKGROUND OF THE INVENTION Drilling tools of this kind with working inserts of hard material are provided in such a way that a given working capacity can be achieved with less energy consumption. An arrangement of this kind is disclosed in EP 122893.

Although the sharp front end (front tip) of the insert is intended to exert a cutting or breaking action in this type of low energy consumption drilling tool, the tool body of a material softer than the insert is It suffers wear and tear due to shock and wear during operation. As one of the results,
The insert weakens the connection to the tool body. After that, the insert will come off, causing the tool to fail prematurely, i.e. prematurely.

With regard to the tool construction shown in EP 122893, when the insert is of a simple cylindrical shape with a conical tip, there is a greater tendency to face problems of this kind. In other configurations, the insert has a cone with a larger diameter than the hole into which the insert fits,
The outer region of this large diameter cone protects the front end of the body. However, inserts of this type of shape are more difficult to make. It is difficult to adapt to the pressure sintering method in which this complicated shape has to be applied to manufacturing.

The SU899916 uses an insert with a large disc-shaped skirt over substantially the entire length,
It has been proposed that the skirt covers the front surface around this fitting hole when the cylindrical rear end of the insert is fitted into the hole in the front end of the tool body. This is EP1
Although the amount of material required to make the large conical portion of the insert shown in 22893 is small, the skirt shape cannot be satisfactorily manufactured by the sintering method. It is not possible to evenly apply the very high sintering pressures required, and thus premature failure of the sintered manufactured insert.

DE 2442146 and DE 3005685
Discloses a case in which the front part of the tool body is composed of a base material in which a hard material is mixed. Even with this, the problem of wear cannot be overcome. It is a steel base material of relatively soft material mixed with hard material exposed to the outside,
Therefore, even if the particles of the mixed hard material do not wear, these particles will separate when the steel of the base material wears. Therefore, if the content of hard metal in the base material is increased to avoid this disadvantage, this does not simplify the manufacture of the tool, but also increases the material cost.

The tool disclosed in GB2004315 has a hard metal tubular ring as a tool body reinforcement on the outer periphery of the leading end of the tool body, but the metal tool body is exposed between the ring and the insert and wears. Suffer. Furthermore, to the extent that the outer ring protects the tool from wear, it cannot be used as a solution for the production of so-called low energy tools. The reason is that this kind of effect is exerted only when the entire front end of the tool is involved in the cutting or breaking action.

Finally, an example of a tool that can be considered similar to that of GB2004315 will be given. In these cases, the hard metal outer ring is replaced with a hard metal layer that extends as a complete sheath over at least the front of the shank. An example of which is disclosed in US Pat. No. 4,682,987,
Hard metal is applied to the shank as a melt coating,
This is obviously a complicated and expensive solution. US3
627387 discloses, as another example, a significantly thicker sheath of hard metal, which further increases tooling costs.

[0009]

SUMMARY OF THE INVENTION The present invention is to eliminate the above problems.

[0010]

SUMMARY OF THE INVENTION In accordance with the present invention, a tool comprising a body portion held in a hole in the front end of the tool body and a working insert having a tapered front end tip projecting from the hole. A ring of a separate article surrounds the insert body and covers the front surface of the tool body, both the insert and the ring being fixed to the tool body at predetermined places, and made of a material harder than the tool body. Tools are provided.

A radial clearance is preferably provided between the ring and the insert.

[0012]

The ring acts as a simple and economical shield for the shield over most of the area of the tool body. The function of the play not only simplifies the construction of the tool, but also simplifies the fixing of the ring and insert to the tool body in place. That is, when the ring and the insert are fixed by soldering, the gap between the insert and the hole should be maintained when the insert that the melt of the solder alloy put in the body hole should be retained in the body hole next time. It flows out through and penetrates between the ring and the body, so that the ring and insert can be soldered to the tool body at the same time.

Various types of rings can be adopted. Flat annular rings have the advantage of ease of manufacture in that individual rings can be easily formed by cutting individual rings from extruded tubes of ring material prior to sintering. The ring does not have to be a closed ring and can be made up of several segments. This segment type ring is preferred when a ring type other than a flat annular ring is required.

The insert may also take various forms with respect to the exposed cutting tip of the insert and the insert body part inserted in the tool body. Generally, the cutting tip of the insert is rotationally symmetric, but can be conical or spherical. Generally, the insert body is most conveniently cylindrical, but its cross section need not be circular.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An example tool of the invention is shown in FIG. The body 2 of this tool is conventionally made of steel and has a central cylindrical shank 4 into which a tool is rotatably inserted in a shaft hole of a holder (not shown). The shoulder 6 at the front end of the shank 4 provides an abutment surface 8 which limits the limit of tool insertion into the holder shaft bore. The shank 4 has a small diameter portion 10,
A lock ring (not shown) is attached to this so that the tool can be retained in the shaft hole.

The tool body 2 has a tapered front portion 1 at its front end.
2 has a round shaft hole 14 having an opening on the front tapered surface
A hard metal cutting insert 20 is received therein, and a cylindrical body portion 22 of the insert projects from the shaft hole. A generally conical tip is formed at the front end of the protruding body. The tool body has a flat annular surface 6 surrounding the shaft hole 14 at its front end, and the flat surface 6 is covered by a ring 30 having a rectangular cross section and having a separate section. The outer diameter of the ring is such that the tangent line T connecting the surface of the tapered tip 24 and the outer circumference of the ring has a larger inclination angle with respect to the major axis L of the tool than the tapered surface of the front part of the main body immediately behind the ring, and the main body has the tangent line T. Is selected to be included in the virtual rotating cone envelope E defined by In order to avoid premature wear of the ring 30, the tangent line T connecting the tip 24 and the ring 30 is inclined at an angle not greater than about 40 ° with respect to the tool axis. Between the insert 20 and the ring 30, for example, there is a clearance not substantially larger than 0.5 mm, preferably not larger than 0.2 mm.

The insert 20 and the ring 30 are fixed to the tool body by soldering. Molten solder material (not shown)
Inserts the insert 20 into the shaft hole 14 before inserting the insert 20 into the shaft hole 14, and when the insert is then inserted, the molten solder material climbs up the side surface of the shaft hole and partially flows out. It is possible to intrude between each of the main bodies 2. In this way, both parts 20, 30 can be soldered to the tool body 2 at the same time.

However, the present invention is not limited to the above-mentioned soldering mode of FIG. 1. For example, as shown in FIG. 2, in the above-mentioned example, the solder material is made to flow out onto the ring 30 and this outflowing solder material is used. The tip 24 and the ring 30 may be additionally fixed with W. Alternatively, even when there is no such outflow, the tip 24 and the ring 30 may be similarly fixed with the additional solder material W as shown in the drawing. Further, the tip 24 and the tool body 2 may be fixed to each other in the shaft hole 14 with one solder material, and the tip 24 and the ring 30 may be fixed to each other with another solder material W (same quality is used) as shown in the figure. Of course, in any case, it is necessary to set the outer shape of the solder material W on the surface of the ring 30 so as to be included in the virtual rotary cone envelope E as illustrated.

Depending on the application, the ring may be shaped differently, but in any case it must be provided as a part to be assembled with the insert in the shank. For special applications, the inserts and rings may be made of other materials, such as cubic boron nitride, polycrystalline diamond, or multi-material compositions. Moreover, these two parts can be made of different materials to reflect different functions.

[0020]

In use of the tool, the ring 30 acts as a simple and economical shield over most of the exposed portion of the tool body 2 to reduce wear of the tool body around the insert, Therefore, the tool life is extended.

[Brief description of drawings]

FIG. 1 is a partially cutaway front view of a drilling tool according to the present invention.

FIG. 2 is a partially cutaway front view corresponding to FIG. 1, showing another example of the soldering aspect of the drilling tool according to the present invention.

[Explanation of symbols]

 2 ... Tool body 12 ... Tool body front part 14 ... Body front part axial hole 16 ... Body front part flat surface 20 ... Insert 22 ... Insert body part 24 ... Insert tip 30 ... Ring T ... Tangent line E ... Virtual conical envelope W ... Solder material

Claims (7)

[Claims] A drilling tool comprising a tool body (2), a working insert (20) having an insert body portion inserted in a hole at a front end and a tapered tip (24) protruding from the hole. The insert (20), ring (30) at a position where the ring (30) of the part surrounds the insert body and covers the front surface (16) of the tool body (20).
And the tool body (2) is fixed, and both parts (20, 30) are molded from a material harder than the tool body (2). 2. Drilling tool according to claim 1, characterized in that there is a radial clearance between the ring (30) and the insert (20). 3. Drilling tool according to claim 2, characterized in that the ring (30) has an annular flat surface. 4. Drilling tool according to claim 3, characterized in that the holed front surface (16) of the tool body (2) on which the ring (30) is seated is an annular flat surface. 5. A tool body (2) in an imaginary rotating cone envelope, the tangent (T) of which connects the outer surface of the tapered tip (24) of the insert (20) and the outer circumference of the ring (30) with respect to the major axis of the tool. The drilling tool according to any one of claims 1 to 4, wherein the tool body (2), the insert (20) and the ring (30) are molded so as to include the above. 6. The tool body (2) has a tapered front portion (12), the inclination angle of the tangent (T) with respect to the major axis of the tool being the taper surface of the front portion (12). The excavating tool according to claim 5, wherein the excavating tool has a larger inclination angle. 7. The insert (20), the tip (24) and the tool body (2) are integrally joined with a solder material so that the solder material used is contained in the virtual rotary cone envelope. The drilling tool according to claim 5, wherein the drilling tool is a drilling tool.