Cutting Bit With Split Wear Ring

Abstract

A cutting bit includes an elongate body having a shank portion and a head portion with a forward end. The head portion has an annular channel defined therein adjacent to and rearwardly of the forward end of the head portion. The annular channel has an angled bottom surface. The cutting bit also includes a split wear ring positionable in the annular channel and structured and arranged to be retainably held in the annular channel. The cutting bit further includes a hard cutting tip affixed to the forward end of the head portion.

Description

BACKGROUND OF THE INVENTION

[0001] The present invention relates to road milling, mining and excavating tools, and more particularly relates to cutting bits with wear rings that reduce wear of such tools.

[0002] Cutting bits are used in various road milling, mining and excavating operations. The bits are mounted on a support structure such as a rotary drum. Each bit typically has a hard wear resistant tip made of a material such as tungsten carbide attached to a generally conical steel head of the bit. A problem with such designs is that the softer steel backing material erodes during cutting operations.

[0003] Wear resistant cutting bits have been developed in order to increase erosion resistance. For example, U.S. Pat. No. 7,530,642 discloses the use of wear rings positioned in an annular channel formed in a cutting bit body. However, it has been found that these wear rings are difficult to assemble and retain in place during the manufacturing process, e.g. while brazing the wear rings in the channel in the cutting bit body. In addition, a steel retainer ring is needed to hold the wear rings in place during the manufacturing process.

[0004] Thus, it can be appreciated that it would be highly desirable to provide an improved cutting bit with improved wear resistance. It can also be appreciated that it would be highly desirable to provide such an improved cutting bit that is easier and more affordable to manufacture.

SUMMARY OF THE INVENTION

[0005] In accordance with an aspect of the invention, a cutting bit includes an elongate body having a shank portion and a head portion with a forward end, wherein the head portion has an annular channel defined therein adjacent to and rearwardly of the forward end of the head portion. The annular channel has an angled bottom surface. The cutting bit also includes a split wear ring positionable in the annular channel and structured and arranged to be retainably held in the annular channel, and a hard cutting tip affixed to the forward end of the head portion.

[0006] In accordance with another aspect of the invention, a split wear ring for positioning in an annular groove formed on a head portion of a cutting bit having a central longitudinal axis includes an angled lower surface and an opposing angled upper surface. The angled lower surface and the opposing angled upper surface are structured and arranged to be retainably held in the annular channel.

[0007] In accordance with an additional aspect of the invention, an elongate body of a cutting bit adapted to receive a split wear ring includes a shank portion and a head portion with a forward end. The head portion has an annular channel defined therein adjacent to and rearwardly of the forward end of the head portion. The annular channel is structured and arranged to retainably hold the split wear ring therein.

[0008] These and other aspects of the present invention will be more fully understood following a review of this specification and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] FIG. 1 is an isometric view of a cutting bit, in accordance with an aspect of the invention.

[0010] FIG. 2 is a partial sectional view of the cutting bit shown in FIG. 1, in accordance with an aspect of the invention.

[0011] FIG. 3 is an additional partial sectional view similar to FIG. 2 with parts removed, in accordance with an aspect of the invention.

[0012] FIG. 4 is an isometric view of a split wear ring, in accordance with an aspect of the invention.

[0013] FIG. 5 is an isometric view of a section of the split wear ring shown in FIG. 4, in accordance with an aspect of the invention.

[0014] FIG. 6 is a partial, front sectional view of the section of the split wear ring shown in FIG. 5, in accordance with an aspect of the invention.

DETAILED DESCRIPTION

[0015] Referring to FIGS. 1-3, there is illustrated a cutting bit, generally designated as reference number 10, in accordance with aspects of the invention. It will be appreciated that the invention has application to various kinds of cutting tools useful in various kinds of cutting operations. Exemplary operations include, without limitation, road planing (or milling), coal mining, concrete cutting, and other kinds of cutting operations wherein a cutting bit with a hard cutting member impinges against a substrate (e.g., earth strata, pavement, asphaltic highway material, concrete, and the like) breaking the substrate into pieces of a variety of sizes including larger-size pieces or chunks and smaller-sized pieces including dust-like particles. In addition, it will be appreciated that the cutting bit 10 of the invention may be manufactured in various sizes and dimensions depending upon the desired application of the tool.

[0016] Cutting bit 10 has a central longitudinal axis X-X. Cutting bit 10 includes an elongate body, generally designated as 12, which typically is made of, for example, steel. Elongate body 12 has an axial forward end 14 and an axial rearward end 16.

[0017] Elongate body 12 further includes a head portion 18 adjacent the axial forward end 14 and a shank portion 20 adjacent the axial rearward end 16. The shank portion 20 may be provided with various shapes and configurations. In one aspect, the shank portion 20 may be structured and arranged to be non-rotatable such that the cutting bit 10 is a non-rotatable type cutting tool. In another aspect, the shank portion 20 may be structured and arranged to be rotatable such that the cutting bit 10 is a rotatable type cutting tool.

[0018] In accordance with another aspect of the invention, the cutting bit 10 further includes a hard cutting tip, generally designated as reference number 22 adjacent the axial forward end 14 (see, for example, FIGS. 2 and 3). The hard cutting tip 22 may be affixed by, for example, brazing the hard cutting tip 22 to, for example, socket 24 formed in the head portion 18 adjacent the axial forward end 14 of the body 12.

[0019] In one aspect, the hard cutting tip 22 is structured and arranged so as to include a substrate 26 (see, for example, FIG. 2) which may be made from, for example, a hard material such as, for example, cemented (cobalt) tungsten carbide. The hard cutting tip 22 may further include a layer of a superhard material 28 adhered to the substrate 26 (see, for example, FIGS. 1 and 2). The layer of superhard material 28 may include, for example, polycrystalline diamond (PCD) or polycrystalline cubic boron nitride (PCBN).

[0020] The layer of superhard material 28 may have a generally constant thickness and can be applied to the substrate 26 by any one of the number of known techniques wherein the superhard material 28 is, for example, bonded to the surface of the substrate 26. For example, one can apply the layer of superhard material 28, e.g. PCD, to the substrate 26 by any one of a number of techniques wherein the layer of superhard material 28 is bonded to the surface of the substrate 26. The following patent documents disclose exemplary compositions of polycrystalline diamond as well as exemplary techniques to apply a layer of polycrystalline diamond to the surface of a substrate: U.S. Pat. No. 4,063,909 to Mitchell, U.S. Pat. No. 4,604,106 to Hall et al., U.S. Pat. No. 4,694,918 to Hall, and U.S. Pat. No. 4,811,801 to Salesky et al.

[0021] In addition, the head portion 18 defines an annular channel 30. The annular channel 30 is adjacent to and rearwardly of the axial forward end 14 of the head portion 18. In one aspect, the annular channel 30 extends at least partially circumferentially about an outer surface 32 of the head portion 18. In another aspect, the annular channel 30 extends circumferentially about the head portion 18 so as to form a continuous groove or channel.

[0022] The annular channel 30 includes a sloped or angled bottom surface 34, an angled top surface 36 generally opposed to the angled bottom surface 34, and a side wall 38 extending between the angled bottom surface 34 and the angled top surface 36. The side wall 38 may be sloped, angled or parallel with respect to the central longitudinal axis X-X of the cutting bit 10.

[0023] In an aspect of the invention, the angled bottom surface 34 is generally planar. In another aspect, the angled bottom surface 34 extends in a plane at an angle A (see, for example, FIG. 3) with respect to the central longitudinal axis X-X of the cutting bit 10. In one aspect, angle A is less than 90 degrees. In another aspect, angle A is in the range of about 60 degrees to about 70 degrees.

[0024] In an aspect of the invention, the angled top surface 36 is generally planar. In another aspect, the angled top surface 36 extends in a plane at an angle B (see, for example, FIG. 2) with respect to the central longitudinal axis X-X of the cutting bit 10. In one aspect, angle B is less than 90 degrees. In another aspect, angle B is in the range of about 60 degrees to about 70 degrees.

[0025] Referring to FIGS. 1, 2 and 4-6, the cutting bit 10 further includes a split wear ring, generally designated as reference number 40. The split wear ring 40 is positionable in the annular channel 30. The hardness, size and location of the split wear ring 40 are selected in order to significantly reduce erosion and wear of the relatively soft body 12 of the cutting bit 10. The split wear ring 40 may be made of any suitable hard material such as carbides, aluminum oxide, hard ceramic materials, hardened tool steels and the like. For example, the split wear ring 40 may be made of tungsten carbide. In one example, the split wear ring 40 and cutting tip 22 are made of the same hard material. Furthermore, portions of the split wear ring 40 may be made of different materials, e.g., materials having different hardness and/or toughness properties, graded materials, and the like.

[0026] In one aspect of the invention, the split wear ring 40 comprises two or more split wear ring sections 40a that are arranged to make the split wear ring 40. For example, FIG. 4 illustrates two split wear ring sections 40a arranged end to end to form the split wear ring 40. However, it will be appreciated that any other suitable number of split wear ring sections may be used, such as three sections, four sections, etc. In one aspect, the split wear ring sections 40a may have flat faces 42 which abut each other when assembled in the annular channel 30.

[0027] As described, the split wear ring 40 is positionable in the annular channel 30. In accordance with an important aspect of the invention, the split wear ring 40 is structured and arranged to be retainably held in the annular channel 30 when positioned therein. As used herein, the terms "retainably held" or "retainably hold" generally refer to the structure of the split wear ring 40 being such that it cooperates with the structure of the annular channel 30 so as to retain and hold the split wear ring 40, i.e. the split wear ring sections 40a, within the annular channel 30 during assembly of the cutting bit 10 without the need for any additional means for holding the split wear ring 40 in position, such as a retainer ring, during assembly. During assembly of the cutting bit 10, the split wear ring sections 40a are first positioned in the annular channel 30. Then, the split wear ring sections 40a go through a process to permanently secure or affix the split wear ring 40 to the head portion 18 and, more particularly, to permanently secure or affix the split wear ring 40 within the annular channel 30. This process may be, for example, a brazing process during which it is important that the split wear ring sections 40a are securely retainably held in place so as to be properly positioned within the annular channel 30. In one example, the cutting bit 10 may be maintained in a generally upright vertical position, such as the orientation shown in FIG. 2, during the brazing process or alternatively the cutting bit 10 may be maintained in a generally downward vertical position, such as turned 180 degrees from the orientation shown in FIG. 2, during the brazing process. Advantageously, the novel structure and arrangement of the annular channel 30 and the split wear ring 40 of the invention and the cooperation of these components allow for the correct, efficient and economical assembly of the cutting bit 10.

[0028] In one aspect, the split wear ring 40 includes an angled lower surface 44 that is positioned adjacent to the angled bottom surface 34 of the annular channel 30. The angled lower surface 44 effectively cooperates with the angled bottom surface 34 of the annular channel 30 so as to retainably hold the split wear ring 40 in the annular channel 30 during assembly.

[0029] In another aspect, the split wear ring 40 also includes an angled upper surface 46 that is positioned adjacent to the angled top surface 36 of the annular channel 30. The angled upper surface 46 effectively cooperates with the angled top surface 36 of the annular channel 30 so as to further retainably hold the split wear ring 40 in the annular channel 30 during assembly.

[0030] Thus, it will be appreciated that the angled lower surface 44 and the angled upper surface 46 of the split wear ring 40 are structured and arranged to advantageously cooperate with and be retainably held in the annular channel 30. In addition, it will be appreciated that the angled bottom surface 34 and the angled top surface 36 of the annular channel 30 are structured and arranged to advantageously cooperate with and retainably hold the split wear ring 40 therein.

[0031] In an aspect of the invention, the angled lower surface 44 of the split wear ring 40 is generally planar. In another aspect, the angled lower surface 44 extends in a plane at an angle C to a center axis X1-X1 of the split wear ring 40 that is perpendicular to a longitudinal axis L-L of the split wear ring 40 (see, for example, FIG. 6). In one aspect, angle C is less than 90 degrees. In another aspect, angle C is in the range of about 60 degrees to about 70 degrees. Thus, it will be appreciated that in one aspect the angled lower surface 44 of the split wear ring 40 may have the same angle or may have a different angle as the angled bottom surface 34 of the annular channel 30.

[0032] In an aspect of the invention, the angled upper surface 46 of the split wear ring 40 is generally planar. In another aspect, the angled upper surface 46 extends in a plane at an angle D to a center axis X1-X1 of the split wear ring 40 that is perpendicular to a longitudinal axis L-L of the split wear ring 40 (see, for example, FIG. 6). In one aspect, angle D is less than 90 degrees. In another aspect, angle D is in the range of about 60 degrees to about 70 degrees. Thus, it will be appreciated that in one aspect the angled upper surface 46 of the split wear ring 40 may have the same angle or may have a different angle as the angled top surface 36 of the annular channel 30.

[0033] Whereas particular aspects of this invention have been described above for purposes of illustration, it will be evident to those skilled in the art that numerous variations of the details of the present invention may be made without departing from the invention as defined in the appended claims.

Claims

1. A cutting bit comprising: an elongate body having a shank portion and a head portion with a forward end, wherein the head portion has an annular channel defined therein adjacent to and rearwardly of the forward end of the head portion, the annular channel having an angled bottom surface; a split wear ring positionable in the annular channel and structured and arranged to be retainably held in the annular channel; and a hard cutting tip affixed to the forward end of the head portion.

2. The cutting bit of claim 1, wherein the split wear ring has an angled lower surface positioned adjacent to and for cooperating with the angled bottom surface of the annular channel to retainably hold the split wear ring in the annular channel.

3. The cutting bit of claim 2, wherein the annular channel includes an angled top surface generally opposed to the angled bottom surface and a side wall extending between the angled bottom surface and the angled top surface.

4. The cutting bit of claim 3, wherein the split wear ring has an angled upper surface positioned adjacent to and for cooperating with the angled top surface of the annular channel to retainably hold the split wear ring in the annular channel.

5. The cutting bit of claim 1, wherein the angled bottom surface is generally planar and extends in a plane at an angle A to a central longitudinal axis of the elongate body, wherein the angle A is less than 90 degrees.

6. The cutting bit of claim 5, wherein the angle A is in the range of 60 degrees to 70 degrees.

7. The cutting bit of claim 3, wherein the angled top surface is generally planar and extends in a plane at an angle B to a central longitudinal axis of the elongate body, wherein the angle B is less than 90 degrees.

8. The cutting bit of claim 7, wherein the angle B is in the range of 60 degrees to 70 degrees.

9. The cutting bit of claim 4, wherein: the angled lower surface is generally planar and extends in a plane at an angle C to a center axis of the split wear ring that is perpendicular to a longitudinal axis containing the split wear ring, wherein the angle C is less than 90 degrees; and the angled upper surface is generally planar and extends in a plane at an angle D to a center axis of the split wear ring that is perpendicular to a longitudinal axis containing the split wear ring, wherein the angle D is less than 90 degrees.

10. The cutting bit of claim 1, wherein the split wear ring includes two sections.

11. The cutting bit of claim 1, wherein the split wear ring includes adjacent sections that contact each other at abutting faces.

12. A split wear ring for positioning in an annular channel formed on a head portion of a cutting bit having a central longitudinal axis, the split wear ring comprising: an angled lower surface; and an opposing angled upper surface, wherein the angled lower surface and the opposing angled upper surface are structured and arranged to be retainably held in the annular channel.

13. The split wear ring of claim 12, wherein the angled lower surface is generally planar and extends in a plane at an angle C to a center axis of the split wear ring that is perpendicular to a longitudinal axis containing the split wear ring, wherein the angle C is less than 90 degrees.

14. The split wear ring of claim 12, wherein the angled upper surface is generally planar and extends in a plane at an angle D to a center axis of the split wear ring that is perpendicular to a longitudinal axis containing the split wear ring, wherein the angle D is less than 90 degrees.

15. The split wear ring of claim 12, wherein the split wear ring includes two sections.

16. The split wear ring of claim 12, wherein the split wear ring includes adjacent sections that contact each other at abutting faces.

17. An elongate body of a cutting bit adapted to receive a split wear ring, the elongate body comprising: a shank portion; and a head portion with a forward end, wherein the head portion has an annular channel defined therein adjacent to and rearwardly of the forward end of the head portion, the annular channel structured and arranged to retainably hold the split wear ring therein.

18. The elongate body of claim 17, wherein the annular channel includes an angled bottom surface, an angled top surface generally opposed to the angled bottom surface and a side wall extending between the angled bottom surface and the angled top surface.

19. The elongate body of claim 18, wherein the angled bottom surface is generally planar and extends in a plane at an angle A to a central longitudinal axis of the elongate body, wherein the angle A is less than 90 degrees.

20. The elongate body of claim 18, wherein the angled bottom surface is generally planar and extends in a plane at an angle B to a central longitudinal axis of the elongate body, wherein the angle B is less than 90 degrees.