Patent Application
20110241409
The invention pertains to a rotatable cutting tool that is useful for the impingement of earth strata such as, for example, asphaltic roadway material, coal deposits, mineral formations and the like. More specifically, the present invention pertains to a rotatable cutting tool that is useful for the impingement of earth strata wherein the cutting tool body possesses improved design so as to provide for improved performance characteristics for the rotatable cutting tool.
Rotatable cutting tools have been used to impinge earth strata such as, for example, asphaltic roadway material or ore bearing or coal bearing earth formations or the like. Generally speaking, these kinds of rotatable cutting tools have an elongate cutting tool body (typically made from steel) and a hard tip (or insert) affixed to the cutting tool body at the axial forward end thereof. The hard tip is typically made from a hard material such as, for example, cemented (cobalt) tungsten carbide. The rotatable cutting tool is rotatably retained or held in the bore of a tool holder or, in the alternative, in the bore of a sleeve that is in turn held in the bore of a holder.
The holder is affixed to a driven member such as, for example, a driven drum of a road planing machine. In some designs, the driven member (e.g., drum) carries hundreds of holders wherein each holder carries a rotatable cutting tool. Hence, the driven member may carry hundreds of rotatable cutting tools. The driven member is driven (e.g., rotated) such that the hard tip of each one of the rotatable cutting tools impinges or impacts the earth strata (e.g., asphaltic roadway material) thereby fracturing and breaking up the material into debris.
As can be appreciated, during operation the entire rotatable cutting tool is typically subjected to a variety of extreme cutting forces and stresses in an abrasive and erosive environment. Rotatable cutting tools having a cutting tool body with various shapes and designs have been provided to most efficiently and effectively operate in these extreme cutting environments. However, it would be undesirable for the cutting tool body to prematurely wear or fail (whether it be through catastrophic fracture or the like or through abrasive or erosive wear) prior to the hard cutting tip wearing to the point of its useful life. In such a circumstance, the rotatable cutting tool would have to be replaced prior to the normally scheduled time for replacement. Further, the premature failure of the rotatable cutting tool would negatively impact the cutting or milling efficiency of the overall earthworking apparatus. It thus becomes apparent that it is important and desirable that the cutting tool body possess the requisite design and strength to maintain its integrity during the intended useful life of the rotatable cutting tool while still providing an efficient and effective rotatable cutting tool.
An aspect of the present invention is to provide a rotatable cutting tool for use in impinging earth strata wherein the rotatable cutting tool comprises a cutting tool body and a hard tip affixed to the cutting tool body. The cutting tool body includes an axial forward end for receiving the hard tip and an axial rearward end, a head portion axially rearward of the axial forward end, a collar portion axially rearward of the head portion, and a shank portion axially rearward of the collar portion and axially forward of the axial rearward end. The head portion includes a plurality of elongated projections extending radially thereabout, each of the elongated projections including a first tapered side and a second tapered side. The first tapered side of each of the elongated projections adjoins the second tapered side of an adjacent elongated projection at a surface of the head portion.
A further aspect of the present invention is to provide a rotatable cutting tool body with a central longitudinal axis wherein the rotatable cutting tool body comprises a head portion, a shank portion, and a collar portion mediate of and contiguous with the head portion and shank portion. The cutting tool body further includes an axial forward end adjacent to the head portion and an axial rearward end adjacent to the shank portion. The head portion includes a plurality of elongated projections extending radially thereabout, each of the elongated projections comprising a first tapered side and a second tapered side, wherein the first tapered side of each of the elongated projections adjoins the second tapered side of an adjacent elongated projection at a surface of the head portion.
Another aspect of the present invention is to provide a rotatable cutting tool having a hard tip affixed thereto for use in impinging earth strata wherein the rotatable cutting tool comprises a head portion, a shank portion, and a collar portion mediate of and contiguous with the head portion and shank portion. The head portion includes a plurality of generally V-shaped longitudinal grooves extending from adjacent the collar portion to adjacent an axial forward end adjacent to the head portion.
These and other aspects of the present invention will be more fully understood following a review of this specification and drawings.
Still referring to
The cutting tool body 22 is divided into three principal portions; namely, a head portion, a collar portion and a shank portion. The most axial forward portion is a head portion (see bracket 32). The head portion 32 begins at the axial forward end 24 and extends along longitudinal axis L-L in the axial rearward direction.
The mediate portion is the collar portion (see bracket 38). The collar portion 38 begins at the juncture with the head portion 32 and extends along the longitudinal axis L-L in the axial rearward direction.
The most axial rearward portion is the shank portion (see bracket 44). Beginning at the juncture with the collar portion 38 and extending along the longitudinal axis L-L in the axial rearward direction, the shank portion 44 comprises a forward cylindrical tail section 48, followed by a retainer groove 50, and terminating in a rearward cylindrical tail section 52. As is known by those skilled in the art, the shank portion 44 is the portion of the cutting tool body 22 that carries the retainer (not illustrated). The retainer rotatably retains the rotatable cutting tool in the bore of a tool holder (not illustrated) or the bore of the sleeve carried by a holder. While the retainer can take on any one of many geometries, a retainer suitable for use with this cutting tool body is shown and described, for example, in U.S. Pat. No. 4,850,649 to Beach et al., which is hereby incorporated by reference.
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The longitudinal grooves 66 are formed by, for example, forged cold or warm cast metal or powdered metal.
As shown in
In accordance with another aspect of the invention, each of the elongated projections 54 can be hardened for increased strength and may have, for example, a hardness in the range of about 40 hrc to about 80 hrc. In one aspect, the apex 62 of each projection 54 can be hardened to a desired depth threw a process of case hardening, or controlling the depth of induction heat treatment. This allows the apex 62 to be harder than the core which results in better wear resistance and in turn better life while maintaining strength through the core of the tool 20.
In accordance with aspects of the invention, it will be appreciated that the design of the cutting tool 20 is tapered toward the tip 30 while the elongated projections 54 slim down the profile and surface size of the head portion 32. This allows the tool 20 to have better penetration while maintaining overall strength. In another aspect, it will be appreciated that the design of the tool 20 allows for material, e.g. earth strata being cut to accumulate or pack in between the elongated projections 54 so as to serve as a wear protector this reducing wear on the tool 20.
Whereas particular embodiments 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.
