Patent Application
20060238016
Cutting bit assemblies for such applications as mining or road milling typically comprise a cutting bit, sometimes referred to as a cutting pick or cutting tool, rotatably mounted within a support block. The support block is, in turn, mounted onto a drum or other body, typically by welding, which is, in turn, driven by a suitable drive means. When a number of such support blocks carrying cutting bits are mounted onto a drum, and the drum is driven, the cutting bits will engage and break up the material (e.g., earth strata) to be mined or removed. The general operation of such a mining machine or construction machine (e.g., a road planing machine) is well known in the art.
Heretofore, various retainers have been proposed or used to mount a cutting bit, rotatable or otherwise, within a support block.
As one example of such a retainer, U.S. Pat. No. 4,505,058 to Peterson shows a retainer having two legs. This retainer is to be used in conjunction with a support block having a recess with specially configured sidewalls that cooperate with the bends in the retainer legs to hold the retainer in place.
As another example, U.S. Pat. No. 4,883,129 to Lonn et al. shows another retainer that overlaps a cutting bit shank and a support block along substantially the entire length of the retainer. This retainer provides a single, continuous shear zone along its entire length.
As still another example, U.S. Pat. No. 6,428,110 to Ritchey et al. discloses a retainer used to retain a cutting bit in a holder. The retainer is stamped out of a piece of sheet steel and is received within an annular grove adjacent to the axial rearward end of the cutting bit. Although this retainer functions in a satisfactory fashion, certain drawbacks occur because the retainer is stamped from sheet steel.
One drawback connected with the stamped retainer of U.S. Pat. No. 6,428,110 is the presence of jagged portions along all or part of the peripheral edge of the retainer. This jagged portion can occur due to tearing or shearing of the material (e.g., steel) during the stamping process. The presence of the jagged portion results in a less than desirable surface finish for the retainer. It would thus be desirable to provide a retainer that presents a surface that does not have jagged portions along its peripheral edge, but instead, has a smooth surface finish along its peripheral edge.
Another drawback connected with the stamped retainer of U.S. Pat. No. 6,428,110 is the presence of so-called “fall off” on the exterior edge of the projections (or ears) that project in a radial outward direction from the retainer body. More specifically, this “fall off” exists when the exterior edge of the projection is not substantially perpendicular to the front or rear surface of the retainer, but instead, has an angled orientation with respect to such surfaces. It would be desirable to provide a retainer that presents projections (or ears) that do not exhibit this “fall off”, but instead, has projections that have an exterior edge that is generally perpendicular to the front and rear surfaces of the projection (or ear).
Still another drawback connected with the stamped retainer of U.S. Pat. No. 6,428,110 is the fact that the grain direction of the steel is dependent upon the direction in which the sheet steel is fed into the stamping press. The grain direction of the steel can run either parallel or perpendicular to the mouth opening of the retainer. It would thus be desirable to provide a retainer that has a consistent grain direction that runs in a direction that is generally parallel to the central longitudinal axis of the retainer body so that the grain direction in the retainer is consistent from part-to-part.
In one form thereof, the invention is a retainer for use in conjunction with a cutting bit wherein the cutting bit includes a shank that contains a recess therein. The retainer includes a generally cylindrical retainer body that has opposite ends and a central longitudinal axis. The retainer body has a generally arcuate shape that defines an arc between the opposite ends thereof. The retainer body further includes at least one ear that projects in a radial outward direction. The retainer body is made from a material that has a grain that runs in a direction generally parallel to the central longitudinal axis of the retainer body.
In still another form, the invention is a method of making a retainer for use in conjunction with a cutting bit wherein the cutting bit includes a shank that contains a recess wherein the steps comprising: providing a generally straight elongate retainer body having opposite ends and a central longitudinal axis, the retainer body being made from a material having a grain that runs in a direction generally parallel to the central longitudinal axis of the retainer body; bending the straight elongate retainer body into an arcuate shape; and swaging the arcuate retainer body so as to form at least one ear that projects in a radial outward direction.
In yet another form, the invention is a cutting bit assembly comprising a cutting bit that has an elongate cutting bit body with an axial forward end and an axial rearward end. The cutting bit body contains a groove adjacent the axial rearward end thereof. The cutting bit assembly further includes a holder that has a central bore that has a forward end and a rearward end. The cutting bit is positioned within the central bore of the holder so as to extend past the rearward end of the bore thereby exposing the groove. A retainer is received within the groove. The retainer comprises a generally cylindrical retainer body that has opposite ends and a central longitudinal axis. The retainer body has a generally arcuate shape defining an arc between the opposite ends thereof. The retainer body further includes at least one ear projecting in a radial outward direction. The retainer body is made from a material having a grain that runs in a direction generally parallel to the central longitudinal axis of the retainer body.
The following is a brief description of the drawings that form a part of this patent application:
Referring to the drawings,
The support block 14 has a cylindrical bore 22 that receives the shank 18 of the cutting bit 12. The bore 22 has a forward end (not illustrated) and a rear end 23. The support block 14 has a base 24 that can be welded or otherwise attached to a track pad 26 of a trenching machine (not illustrated) used to break up material (e.g., earth strata).
When the trenching machine drives the track pad, the cutting bit 12 will engage and break up material to be broken and mined or otherwise removed. Alternatively, the support block 14 may be welded or otherwise attached to a driven rotatable drum (not illustrated) or any other suitable component of a mining machine or a road planing machine wherein during operation the cutting bits engage and break up the earth strata such as coal in the case of a mining machine or asphaltic material in the case of a road planing machine.
Referring to
When taken in conjunction with its cooperation with the annular groove 20 in the shank 18 of the cutting bit 12, the retainer body 30 also defines a continuous shear zone 38 preferably, but not always necessarily, along the entire length of the arc as defined by angle “A”. Referring especially to
In the specific embodiment illustrated in
Referring especially to
Referring to
In order to install the retainer 16 in the recess 20, as illustrated in
When the retainer 16 is installed in the groove 20 contained in the shank 18, the retainer 16 contacts the surfaces that define the annular recess 20 to impede transverse movement of the retainer 16 relative to the shank 18. Alternatively, the retainer 16 may be installed on the shank 18 in any suitable manner.
In order to remove the retainer 16 from the recess 20, as illustrated in
Because the continuous shear zone (illustrated by bracket 38) preferably extends the entire length of the retainer body 30, the retainer 16 has significant strength and durability characteristics. Furthermore, the engagement of the retainer 16 by the installation tool 46 enables the retainer 16 to be easily installed on and removed from the shank 18 as described hereinabove.
It can thus be seen that during operation, the cutting bit 12 is free to rotate relative to the holder 14 and thereby function to engage and break up the earth strata. However, it is also apparent that the retainer 16, which is received within the groove 20, securely retains the cutting bit 12 within the bore 22 of the holder 14. It is also apparent that the retainer 16 can be easily installed and removed through the use of the puller 46 or some other suitable tool so as to decrease the amount of downtime experienced by the machine operator during the replacement of the cutting bits.
In regard to method of making the retainer 16 and referring to
Referring to
Referring to
Referring especially to
It can be seen that the surface of the retainer body 30 is smooth and consistent since the retainer body 30 is made from a cylindrical wire. Although not intended to be restrictive, the surface roughness (Ra) of the cold drawn wire is equal to about 125 microinches. Further, it can be seen, especially by
The fact that the outer edge 42 is perpendicular to the front and rear surfaces of the ear 40 results in a more consistent engagement between the ears 40 and the notches in the puller 46 as compared to a stamped retainer wherein there is “fall off” at the outer edge of the ears. Further, the fact that the surface of the retainer 16 is smooth and consistent results in a more consistent engagement of the retainer 16 by the puller 46 as compared to the stamped retainer that has jagged edge portions. A more consistent engagement between the retainer and the puller provides for more efficient and improved installation and removal of the retainer 16.
The fact that the retainer 16 made from a cylindrical wire that has a grain “G” that runs in a direction generally parallel to the central longitudinal axis of the retainer body results in better consistency between each part as compared to a retainer that is stamped from sheet steel. It is desirable to provide a method that makes the retainer 16 with a part-to-part consistency that has heretofore not been available.
It can thus be appreciated that the present invention defines a retainer that exhibits new and improved properties. More specifically, the retainer of the present invention present a surface that does not have jagged edges, but instead, has a smooth surface finish. Further, the retainer presents projections (or ears) that do not exhibit the “fall off”, but instead, are generally perpendicular to the surface of the face of the projection (or ear). Finally, the retainer that has a consistent grain direction wherein the grain runs in a direction along the length, i.e., along the central longitudinal axis, of the retainer body. This feature provides an improved part-to-part consistency in the manufacture of the retainers.
The patents and other documents identified herein are hereby incorporated by reference herein.
While embodiments of the invention have been illustrated and described, it is not intended that these embodiments illustrate and describe all possible forms of the invention. Other embodiments of the invention will be apparent to those skilled in the art from a consideration of the specification or a practice of the invention disclosed herein. Various changes may be made without departing from the spirit and scope of the invention, which is indicated by the following claims.
