Patent Application
20140319897
The invention pertains generally to an excavating tool such as, for example, a cutter bit useful for cutting through various earth strata and other materials. More specifically, the invention pertains to a flat cutter bit with a cutting insert having edge preparation.
Various types of cutting assemblies having cutter bits are used for mining, construction and related operations wherein, typically, the cutter bits include a shank for insertion into a tool holder and a forward working portion on the shank for engagement with earth strata, e.g., coal, or mineral formation or other natural materials or the like. An individual insert formed of a hard, wear resistant material is provided on the forward working portion to cut into the earth strata and to enhance the life of the cutter bit as it removes the material.
An example of a cutting assembly having cutter bits that are used for mining and construction operations include a flat cutter tool. These types of cutting tools usually include a plurality of cutter bits mounted on a rotatable disc, rake, chain, barrel or drum, wherein each of the cutter bits include a substantially-flat cutting insert made of a hard material. These substantially-flat cutting inserts are affixed to the forward working end of the cutter bits. However, it has been determined that due to the shape and configuration of the substantially-flat cutter inserts, the cutter inserts do not wear uniformly. This non-uniform wear decreases the overall useful life of the cutting inserts. More particularly, the cutting edge of the substantially-flat cutter inserts have a tendency to chip or break during use due to the shape of the cutting edge.
Accordingly, it would be desirable to provide improved cutting tools that overcome limitations and disadvantages of known such tools. In addition, it would be desirable to provide improved cutter bits that overcome limitations and disadvantages of known cutter bits and that provide for improved wear and efficiency during operation. Furthermore, it would be desirable to provide improved cutting inserts for cutter bits that overcome limitations and disadvantages of known cutting inserts and that provide for improved wear and efficiency during operation.
In accordance with another aspect of the invention, a flat cutter bit for engaging, for example, an earth strata material includes a non-rotatable shank portion, a head portion integrally formed with the non-rotatable shank portion and including a tip region distal from the non-rotatable shank portion, and a cutting insert mounted at the tip region of the head portion. The cutting insert includes a body having an angled leading face, a top surface having a relief surface, a T-land surface extending between the angled leading face and the relief surface of the top surface and a cutting edge formed at the intersection of the T-land surface and the relief surface of the top surface.
In accordance with yet another aspect of the invention, a cutting insert for use in connection with a cutter bit for engaging, for example, an earth strata material includes a body having an angled leading face, a top surface having a relief surface, a T-land surface extending between the angled leading face and the relief surface of the top surface and a cutting edge formed at the intersection of the T-land surface and the relief surface of the top surface.
These and other aspects of the present invention will be more fully understood following a review of this specification and drawings.
The following description is for purposes of illustrating various aspects of the invention only and not for purposes of limiting the scope of the invention.
Referring to
The radial cutter bit 110 includes a forward working end that includes a head portion 114 integrally formed with the shank portion 112 and having a tip region 116 distal from the shank portion 112. The cutting insert 122 is mounted at the tip region 116 of the head portion 114. The cutting insert 122 is typically mounted or affixed to or within a socket 117 defined at the tip region 116 of the head portion 114 by, for example, attaching mechanically or otherwise, via brazing, gluing, or press fitting using conventional compositions and techniques known to those skilled in the art.
The cutting insert 122 is made from, for example, a cemented tungsten carbide that is a mixture of cobalt and tungsten carbide. Other super hard, wear resistant materials such as polycrystalline diamond, ceramics, or cermet may be used as a supplement and/or substitute. For example chromium carbide-coated metals and other cermets where titanium carbide or vanadium carbide is added to tungsten carbide may be candidates for inserts materials in accordance to aspects of the invention. Alternate ceramics for such applications include aluminum-based, silicon based, zirconium-based and glass varieties. Still other insert materials alternatives include cubic refractory, transition metal carbides or any other known or subsequently developed material(s) harder than the base material. Also coatings of the inserts such as PVD or CVD coatings can be used.
In one aspect, the cutting insert 122 is made, for example, with a powder metallurgy process using a press comprising of a die and top and bottom ram/punch to press the complete shape. Parts can be pressed to finished shape or modified with a wet/dry blast, or diamond ground other material shaping processes such as but not limited to EDM (electrical discharge machining), EDG (electrical discharge grinding), green machining, laser ablation into final shapes. Advantageously, the invention provides for moving the critical cutting edge of the insert from the intersection of the die case and ram during manufacturing. In accordance with an aspect of the invention, the critical cutting edge is now formed entirely in the ram/punch. This eliminates the flash from forming on the cutting edge. Flash is undesirable because, for example, it is a stress concentrator. It will be appreciated that these and other aspects of the invention as set forth herein contribute to the desired edge, i.e. cutting edge, preparation for the cutting insert.
Cutting insert 122 has a cutting insert body, generally designated as 124, that has a top surface 126, a bottom surface 128, a first side portion 134 and a second side portion 136. The cutting insert body 124 also includes an angled or sloped leading face 140 and an opposite rearward or trailing side portion 142. In one aspect, the angled leading face 140 is generally planar and is generally located on an upper section 143 of the body 124. In another aspect, the body 124 also includes a lower section 145 that has a generally circular cross-sectional shape or configuration.
The top surface 126 of the cutting insert 122 includes a relief surface 144. In one aspect, the relief surface 144 extends toward the rearward or trailing side portion 142 of the cutting insert 122. In another aspect, the relief surface 144 extends to the rearward or trailing side portion 142.
In accordance with another aspect of the invention, the cutting insert 122 includes edge preparation such as a T-land surface, generally designated as 148, extending generally between at least a portion of the angled leading face 140 and the relief surface 144 of the top surface 126. In one aspect, the T-land surface 148 extends between the length of the angled leading face 140 and the relief surface 144. In another aspect, the T-land 148 is contiguous with the angled leading face 140. In yet another aspect, the T-land 148 is contiguous with the relief surface 144. It will be appreciated that the T-land surface 148 may be a planar surface or other than a planar surface, such as, for example it may include a rounded or curved, i.e. non-planar, T-land surface.
The cutting insert 122 further includes a cutting edge 150 formed at the intersection of the T-land surface 148 and the relief surface 144 of the top surface 126. In one aspect, the cutting edge 150 is rounded. In another aspect, the angled leading face 140 and the T-land 148 intersect to form a rounded leading edge 141.
The configuration of having the cutting edge 150 formed at the intersection of the T-land surface 148 and the relief surface 144 provides for the cutting edge 150 to have a negative axial rake angle R (see, for example,
The T-land surface 148 is positioned relative to the relief surface 144 at an angle X (see, for example,
In another aspect, the T-land surface 148 may have a width W (see, for example,
It will be appreciated that the configuration of the T-land 148, cutting edge 150, negative axial rake angle R and/or the relief angle X individually and/or in combination advantageously avoid a sharp transition for the cutting edge 150 so as to reduce or minimize the possibility of the cutting edge 150 breaking or chipping during operation of the cutter bit 110. In addition, the T-land 148 is configured so as to redirect the cutting forces along the cutting edge 150 to reduce the shear stress along the cutting edge 150.
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.
