JPH07197768A - Rotary drilling tools - Google Patents

Abstract

(57) [Summary] [Purpose] A rotary machine equipped with such an advantageous cutting insert, which can effectively excavate for a long period of time with a low cutting force, and avoids loosening the securing for the tool body. Provide drilling tools. [Construction] The insert (11) has a conical tip (1
2), intermediate part (17), shoulder part (13) and tool body (1)
0) bearing surface (14). The middle portion (17) includes a concave surface portion (17 '), and the covering material has a tip portion (12).
Alternatively, it is applied to this, the intermediate part (17) and the shoulder part (13).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary drilling tool including a tool body and a cutting insert fixed to the tool body by soldering or the like for breaking and drilling a hard substance such as asphalt. The cutting insert has a generally conical tip and is shaped to have a shoulder adapted to sit on a bearing surface of the tool body.

[0002]

2. Description of the Related Art A rotary excavating tool is usually rotatably mounted on a tool holder, and this holder is attached to an excavator such as a road planing machine or a mining machine. The tool performs self-sharpening by its rotation. The machine described above may be of the type disclosed in US Pat. No. 4,302,055. Reference is then made to the disclosure of this patent.

As a tool for crushing cast asphalt (mastic), for example, a tool for breaking or excavating a wear-resistant substance of the type shown in FIG. 1 is used.
This tool comprises a tool body 10 made of steel and a cutting insert 11A made of hard metal. The cutting insert 11A comprises a conical tip 12A and a shoulder 13A, which shoulder is a bearing surface 14A of the tool body 10A.
Is intended to abut. The rear contact surface 20A of the shoulder 13A is soldered to the support surface 14A. The cutting insert 11A includes a frustoconical intermediate portion 15A which is located between the tip 12A and the shoulder 13A. The intermediate portion 15A protects the portion of the tool body 10A surrounding the cutting insert 11A against wear that loosens the cutting insert 11A. When excavating wear resistant materials, for example when crushing cast asphalt, the tip 12A is blunted by some wear on the cutting insert 11A, which increases the cutting force for the required excavation. When grinding cast asphalt, the road planing machine can even result in the inability to rotate the tooled cutter due to the increased cutting force required.

One way to reduce the cutting force required on a wear tool is to use a tool of the type shown in FIG. The cutting insert 11B shown in FIG. 2 has a smaller diameter than the cutting insert 11A of FIG. However, this means that the portion 16B of the tool body 10B surrounding the cutting insert 11B is rapidly abraded, which causes the cutting insert 11B to become loose. Therefore, it can be said that the cutting insert of the type shown in FIG. 2 is suitable only for use when a hard metal determines the life of a tool, for example, a tool for grinding concrete.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to require low cutting forces and yet to prevent such cutting inserts from loosening even when they are operating against wear resistant materials. It is to provide a wear resistant tool that suppresses

[0006]

SUMMARY OF THE INVENTION According to the invention, a rotary drilling tool for destroying hard materials having an axially extending tool body having a specific diameter and having an end and a bearing surface;
And a cutting insert made of hard metal having a tip, an intermediate portion and a shoulder, the tip being generally conical, the shoulder having a diameter substantially greater than a maximum diameter of the tip. The intermediate portion extends between the tip and the shoulder so as to define an abrupt transition from the tip and joins the two, the intermediate portion of the tool body Having a maximum diameter substantially smaller than the diameter, the middle portion including a radially outwardly extending concave portion between the tip and the shoulder, the shoulder joining the concave portion. And the cutting insert has a wear-resistant coating on its exposed working surface and is characterized in that it includes a rearward facing contact surface which abuts against the supporting surface of the tool body. Rotary drilling tools are provided.

Further in accordance with the present invention, a rotary drilling tool for breaking hard materials comprising an axially extending tool body having an end of a particular diameter and a bearing surface; and a generally conical tip. Axially and radially extending to define a shoulder having a diameter substantially greater than the maximum diameter of the tip and an abrupt transition from the tip to the shoulder, and both Comprising a hard metal cutting insert having an intermediate portion joined to the portion, the intermediate portion having a maximum diameter substantially less than the diameter of the tool body, the intermediate portion including a concave portion. , The shoulder is joined to the concave portion, the cutting insert has a wear-resistant coating material applied to its exposed working surface, and includes a rearward-facing contact surface that abuts the supporting surface of the tool body. A wear-resistant rotary drilling tool It is.

According to various features of the invention, the wear resistant coating may be diamond and / or cubic boron nitride, in which case one or more non-diamond intermediates such as Ti, TiC or TiN. It is also acceptable to have layers. The concave portion may have a constant radius of curvature. Further, the distance (a) from the abrupt transition portion between the tip and the middle portion of the insert to the outermost edge of the radius of the rearward contact surface of the shoulder is defined as the distance from the abrupt transition portion to the axially tip end of the tip. It can be made larger than (b). The minimum diameter (d) of the concave portion is the sum of both distances (a
It can be smaller than + b).

[0009]

When the abrasion of the cutting insert progresses, the surface area of the intermediate portion only recedes, and the size of the tip portion does not substantially change. Therefore, the excavating ability can be maintained with the same low cutting force as when the insert was first used.

[0010]

DETAILED DESCRIPTION OF THE INVENTION In accordance with the present invention, a low energy attack tool is provided which comprises a wear resistant coating on a cap-shaped cutting insert, the coating being harder than the insert. It is a material. For example,
The insert can be a superhard carbide alloy (cemented carbide) and the coating can be diamond and / or cubic boron nitride. The coating can be applied to the exposed surface of the insert, with or without one or more non-diamond intermediate layers such as Ti, TiC, TiN. This coating can be applied by PVD, CVD, high temperature / high pressure (HT / HP) or other conventional methods. The wear resistant coating and the intermediate layer can each have a layer thickness in the range of about 1.0 μm to about 100 μm, and the total thickness of the coating layer depends on each layer and the number of layers.
It can be 0 μm or more. US Patent No. 5,15
4,245 and 4,707,384 disclose several diamond coating methods applicable for coatings according to the present invention.

The wear resistant coating maintains the insert geometry for a long period of time, thus reducing the amount of dust produced by the tool, reducing the cutting force and the force acting on the tool.
The heat generated by the cutting action of the tool can be reduced and the possibility of sparking (the phenomenon of fireworks scattering) caused by the contact between the cemented carbide tool and the material to be excavated can be reduced.

As shown in FIGS. 3 and 4, the rotary drilling tool according to the present invention comprises a cutting insert 11, which comprises a tip 12 and a shoulder 13 and an intermediate portion 17 therebetween. The intermediate portion 17 includes a concave portion 17 '. Middle part 1
By means of 7, the required cutting force is kept low even when the tip 12 wears out. This is because the tip size is generally maintained at the same level as the chip wear progresses along the middle portion 17. This design prevents premature wear of the steel of the tool body 10 surrounding the cutting insert. This protection is provided by the concave portion 17 'and the shoulder 13.

The wear-resistant coating material 60 is formed on the outer surface of the tip portion 12, the intermediate portion and / or the shoulder portion so as to completely cover the working surface.
Alternatively, it can be applied with a desired pattern that partially covers. Preferably, at least the tip 12 is covered with the covering material 60.

As shown in FIG. 4, the intermediate portion 17 is a pointed portion 1.
2 may include a cylindrical portion 17 ″ adjacent thereto. In the present example, the distance a from the transition portion 18 between the tip 12 and the intermediate portion 17 to the radially outermost edge of the rear contact surface 20 of the shoulder 13.
Is greater than the distance b from the transition portion 18 to the tip of the tip 12 in the axial direction. The rear contact surface 20 is adapted to abut, i.e., seat on the support surface 14 of the tool body 10.

Furthermore, in the illustrated example, the minimum diameter d of the concave portion 17 'is smaller than the sum of the distances a and b. The concave portion 17 'has a constant radius of curvature, which is smaller than 1.5d but larger than 0.5d.

The outer peripheral surface of the cylindrical portion 17 "extends tangentially to the arcuate portion 17 '.

In the illustrated example, the cutting insert has a rear portion projecting rearward from the shoulder portion 13. The rear end face is flat. However, this end surface can be a recessed surface, such as the generally W-shaped or hemispherical shape shown in Swedish Patent Application No. 8400269-0.

As a further modified example, the cutting insert can be molded without the rear projection. In this case, the rear end surface of the cutting insert, that is, the end surface of the shoulder portion and the front surface of the tool body cooperating therewith may be designed like the various deformed end surfaces described above.

[0019]

The drilling tool of the present invention is capable of continuing effective drilling with a low cutting force for a long period of time and avoiding a situation where the cutting insert is loosened with respect to the tool body. It is useful as a long-life rotary drilling tool with improved.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional side view of a conventional tool for breaking hard materials.

FIG. 2 is a partial sectional side view of another conventional tool.

FIG. 3 is a partial cross-sectional side view corresponding to FIGS. 1 and 2, showing an example of a tool according to the present invention.

4 is an enlarged side view of a cutting insert in the tool of FIG.

[Explanation of symbols]

 10 ... Tool body 11 ... Cutting insert 12 ... Tip part (chip) 13 ... Shoulder part 17 ... Intermediate part 17 '... Concave part 17 "... Cylindrical surface part 18 ... Transition part 19 ... End edge 20 ... Contact back surface 60 ... Coating material

Claims (20)

[Claims] 1. A rotary drilling tool for breaking hard materials, the tool body having an end having a specific diameter and a bearing surface; a cutting insert made of hard metal having a tip, an intermediate portion and a shoulder; and A wear resistant coating that is harder than the cutting insert, the coating applied to at least the exposed working surface of the tip, the tip being generally conical and the shoulder Having a diameter substantially greater than the maximum diameter of the tip, the middle portion extending between the tip and the shoulder and joining the two portions to define an abrupt transition from the tip. The intermediate portion has a maximum diameter substantially smaller than the diameter of the tool body, the intermediate portion including a radially outwardly extending concave portion between the tip and the shoulder. , The shoulder is joined to the concave part, and the cutting insert is A rotary drilling tool, characterized in that it comprises a rearward facing contact surface which abuts against said support surface. 2. The rotary drilling tool according to claim 1, wherein the coating material comprises at least one layer of diamond and / or cubic boron nitride. 3. The rotary drilling tool of claim 2, wherein the dressing comprises one or more non-diamond intermediate layers. 4. A rotary drilling tool according to claim 2 or 3, wherein the coating layer comprises a single diamond layer. 5. The rotary drilling tool according to claim 1, wherein the concave portion has a constant radius of curvature. 6. The distance (a) from the abrupt transition portion between the apex portion and the intermediate portion to the radially outermost edge of the rearward facing surface of the shoulder portion is (a) the abrupt transition portion to the apex portion. The rotary drilling tool according to claim 1, which is larger than the distance (b) to the axial tip of the part. 7. The minimum diameter (d) of the concave surface is smaller than the distance (a + b) from the axial tip of the tip to the radially outermost edge of the rearward contact surface of the shoulder. The rotary drilling tool according to item 6. 8. The rotary drilling tool according to claim 1, wherein the dressing covers the tip. 9. The rotary drilling tool according to claim 1, wherein the coating material covers the pointed portion and the intermediate portion. 10. The rotary drilling tool according to claim 1, wherein the dressing covers the pointed portion, the intermediate portion and the shoulder portion. 11. A rotary drilling tool for breaking hard materials, the tool body having an end having a particular diameter and a bearing surface; a generally conical tip, substantially greater than a maximum diameter of the tip. A diametrical shoulder and an intermediate portion extending axially and radially to define an abrupt transition from the tip between the tip and the shoulder and joining the two. A cutting insert made of a hard metal; and an abrasion-resistant coating material made of a material harder than the cutting insert, the coating material being applied to at least the exposed working surface of the tip portion, and the intermediate portion being a tool A maximum diameter substantially smaller than the diameter of the body, the intermediate portion including a concave portion, the shoulder joined to the concave portion, and the cutting insert facing rearwardly against the bearing surface of the tool body. Characterized by including a contact surface , Rotary drilling tools. 12. The coating material comprises at least one layer of diamond and / or cubic boron nitride.
The rotary drilling tool described in. 13. The rotary drilling tool of claim 12, wherein the dressing comprises one or more non-diamond intermediate layers. 14. A rotary drilling tool according to claim 12 or 13, wherein the coating layer comprises a single diamond layer. 15. The rotary drilling tool according to claim 11, wherein the concave portion has a constant radius of curvature. 16. The distance (a) from the abrupt transition between the apex and the middle to the radially outermost edge of the rearward facing surface of the shoulder is (a) apex to apex. A rotary drilling tool according to claim 11, which is greater than the distance (b) to the axial tip of the part. 17. The minimum diameter (d) of the concave surface is smaller than the distance (a + b) from the axial tip of the tip to the radially outermost edge of the rearward contact surface of the shoulder. 1
The rotary drilling tool according to item 6. 18. The rotary drilling tool according to claim 11, wherein the dressing covers the tip. 19. The rotary drilling tool according to claim 11, wherein the dressing covers the pointed portion and the intermediate portion. 20. The rotary drilling tool according to claim 11, wherein the dressing covers the pointed portion, the intermediate portion and the shoulder portion.