Rotational style tool bit assembly

Description

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims priority to U.S. Provisional Application No. 62/366,779, filed Jul. 26, 2016, to the extent allowed by law and the contents of which are incorporated herein by reference in their entireties.

TECHNICAL FIELD

This disclosure relates to bit assemblies for road milling, mining, and trenching equipment.

BACKGROUND

Road milling, mining, and trenching equipment utilizes bits or inserts traditionally set in a bit assembly having a bit holder and a bit holder block. The insert is retained within the bit holder which is retained within a bore in the bit holder block. A plurality of the bit assemblies are mounted on the outside of a rotatable drum, typically in a V-shaped or spiral configuration, or the plates are mounted to a chain driven boom or a wheel trencher. The combinations of bit assemblies have been utilized to remove material from the terra firma, such as degrading the surface of the earth, minerals, cement, concrete, macadam or asphalt pavement. Individual bits, bit holders, and bit holder blocks may wear down or break over time due to the harsh cutting environment. In various trenching cutting conditions, a hardened insert, such as a tungsten carbide insert, is used to initially impact the surface material and break it down into smaller removable pieces which are then carried outside the trenched area to the adjacent surface alongside the trenching machine. The bit assembly of the present disclosure uses a hardened insert in combination with a bit holder having vertical vanes configured to aid in removing the loosened material, assist in the rotation of the tool, and allow the profile at the forward end of the tool to wear symmetrically.

SUMMARY

This disclosure relates generally to bit assemblies for road milling, mining, and trenching equipment. One implementation of the teachings herein is a bit holder that includes a forward body portion comprising a plurality of vanes axially and radially extending from a top surface of the body portion to a generally cylindrical tire portion of the body portion; and a generally cylindrical shank depending axially from the forward body portion, the shank comprising an annular groove adjacent a distal end of the shank.

In another implementation of the teachings herein is a bit holder that includes a forward body portion comprising at least one vane axially and radially extending from a top surface of the body portion to a generally cylindrical tire portion of the body portion; and a generally cylindrical shank depending axially from the forward body portion, the shank comprising an annular groove adjacent a distal end of the shank.

These and other aspects of the present disclosure are disclosed in the following detailed description of the embodiments, the appended claims and the accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

The various features, advantages, and other uses of the apparatus will become more apparent by referring to the following detailed description and drawings, wherein like reference numerals refer to like parts throughout the several views. It is emphasized that, according to common practice, the various features of the drawings are not to-scale. On the contrary, the dimensions of the various features are arbitrarily expanded or reduced for clarity.

FIG. 1 is a top elevation view of an embodiment of a bit assembly;

FIG. 2 is a right side elevation view of the embodiment of the bit assembly of FIG. 1;

FIG. 3 is a front elevation view of the embodiment of the bit assembly of FIG. 1;

FIG. 4 is a right side perspective view of the embodiment of the bit assembly of FIG. 1;

FIG. 5 is a left side perspective view of the embodiment of the bit assembly of FIG. 1;

FIG. 6 is an exploded side elevation view of the embodiment of the bit assembly of FIG. 1;

FIG. 6A is an exploded side elevation view of the embodiment of the bit assembly of FIG. 1; and

FIG. 7 is an exploded perspective view of the embodiment of the bit assembly of FIG. 1.

DETAILED DESCRIPTION

Road milling, mining, and trenching equipment utilizes bits or inserts traditionally set in a bit assembly having a bit holder, comprising a bit holder body and a shank, and a bit holder block. The insert is retained within the bit holder which is retained within a bore in the bit holder block, hereinafter referred to as the base block. The base block supports the tool and is welded to its support member. The combinations of bit assemblies have been utilized to remove material from the terra firma, such as degrading the surface of the earth, minerals, cement, concrete, macadam or asphalt pavement. The tool of the present disclosure is designed to be used in various trenching cutting conditions, whether cutting rock formations, cutting a combination of rock and dirt or soil, or removing strictly soil. The tool includes a hardened insert, such as a tungsten carbide insert, brazed into a pocket or seat at the forward end of the tool. The hardened insert is used to initially impact the surface material and break it down into removable size pieces that fit within the pocket or space between the vanes of the tool and carry the removable size pieces outside the trenched area to the adjacent surface alongside the trenching machine. The spaced cavities of the tool are supported by vertical vanes that also aid in removing loosened material. The vertical vanes of the tool are also configured to aid in the rotation of the tool as well, which allows the profile at the forward end of the tool to wear symmetrically.

Referring to FIGS. 1-7, an illustrated embodiment of a rotational style tool bit assembly 10 comprises a hardened insert 12, a bit holder 14, and a base block 16. The bit holder 14 includes a bit holder body 18 and a shank 20, as shown in FIG. 6, axially depending from the bottom of the bit holder body 18. The bit holder body 18 comprises a forward body portion 24 that extends axially and radially outwardly from a flat top surface 22 to a radially extending generally cylindrical tire portion 26. The tire portion 26 extends downwardly to a chamfer 42, shown in FIG. 6, that defines the outside of a rear flange, such as a rear flat annular flange 44 in this embodiment. A decreased diameter tapered distal portion 46, subjacent to the tire portion 26, extends from the rear flange 44. The flat top surface 22 comprises a generally cylindrical bore 40, shown in FIG. 7, axially and centrally positioned in bit holder body 18, into which the insert 12 may be positioned and brazed.

In this illustrated embodiment, the forward body portion 24 comprises three radially extending wings or vanes 28, 30, 32 that axially extend from the flat top surface 22 to the tire portion 26. The vanes 28, 30, 32 converge proximate the axis of rotation A, shown in FIG. 7, on the flat top surface 22 and diverge radially towards the tire portion 26. Each vane is separated from the next vane by an arcuate cavity or flute. In this illustrated embodiment, shown in FIG. 3, an outer edge 87 of vane 28, an outer edge 88 of vane 30, and an upper edge 93 of tire portion 26 define cavity 34, an outer edge 89 of vane 30, an outer edge 90 of vane 32, and an upper edge 94 of tire portion 26 define cavity 36, and an outer edge 91 of vane 32, an outer edge 86 vane 28, and an upper edge 92 of tire portion 26 define cavity 38. In this illustrated embodiment, vane 28 comprises an outer surface between outer edge 86 and outer edge 87 that includes a concave outer surface 102 (FIGS. 1, 2, 6, and 6A) adjacent the flat top surface 22, a convex outer surface 104 (FIGS. 1, 2, 6, and 6A) adjacent the concave outer surface 102, and a laterally extending outer surface 106 (FIGS. 1, 2, 6, and 6A) adjacent the convex outer surface 104 that extends to the tire portion 26, vane 30 comprises an outer surface between outer edge 88 and outer edge 89 that includes a concave outer surface 108 (FIG. 5) adjacent the flat top surface 22, a convex outer surface 110 (FIG. 5) adjacent the concave outer surface 108, and a laterally extending outer surface 112 (FIG. 5) adjacent the convex outer surface 110 that extends to the tire portion 26, and vane 32 comprises an outer surface between outer edge 90 and outer edge 91 that includes a concave outer surface 114 (FIGS. 2, 6, and 6A) adjacent the flat top surface 22, a convex outer surface 116 (FIGS. 2, 6, and 6A) adjacent the concave outer surface 114, and a laterally extending outer surface 118 (FIGS. 2, 6, and 6A) adjacent the convex outer surface 116 that extends to the tire portion 26. In other contemplated embodiments, the forward body portion of the bit holder includes at least one vane and at least one cavity, where the cavities can be of various shapes. The combination and configuration of the vanes 28, 30, 32 and cavities 34, 36, 38 are configured to direct and move material from a trenched area to the adjacent surface alongside the trenching machine.

The shank 20, coaxial with the bit holder body 18, axially depends from the decreased diameter tapered distal portion 46 of the bit holder body 18. The shank 20 may be solid and may have a single diameter along its entire length, or may have sections of varying diameters. In other embodiments, the shank 20 can be cylindrical or can include tapered and/or arcuate segments. The shank 20 in the illustrated embodiment comprises a generally cylindrical increased diameter first segment 48 that axially extends from the decreased diameter tapered distal portion 46 and a generally cylindrical decreased diameter second segment 50. The first segment 48 is joined to the second segment 50 by a shoulder 52. The second segment 50 axially extends from the shoulder 52 to a tapered distal segment 54 which axially extends to a distal end 56 of the shank 20. The second segment 50 includes an annular groove 58, having an axial length 60, shown in FIG. 6, adjacent the distal end 56 of the shank 20 where it can be engaged by a bit retainer 62. The annular groove 58 of the shank 20 can include an arcuate inner surface, as shown in FIG. 6, or a flat inner surface 59, as shown in FIG. 6A.

The bit retainer 62 includes a metal body having a thickness 82, shown in FIG. 6. The bit retainer 62 includes a pair of arcuate legs 74, 76 that define an aperture 78 of the bit retainer 62, as shown in FIG. 7. A diameter 80, shown in FIGS. 1 and 6, of the aperture 78 is generally at least the diameter of the annular groove 58 of the shank 20, such that the bit retainer 62 can fit around the annular groove 58 of the shank 20. Legs 74, 76 are joined together by an arcuate portion 84, shown in FIG. 7, that defines a radially expandable area.

Referring to FIGS. 6 and 7, the base block 16 comprises a base 64 and a front end 66 having a forward face 68. The base 64 can be flat or slightly concave to fit a drum or additional mounting plates on which a plurality of base blocks can be mounted. The front end 66 includes a base block bore 70 that is coaxial with the shank 20.

The insert 12 is positioned and brazed in the generally cylindrical bore 40 of the flat top surface 22 of the bit holder body 18. The bit holder 14 is then inserted into the base block bore 70 of the front end 66 of the base block 16, forming a minimally spaced contact between the shank 20 and the base block bore 70. The bit holder 14 and the base block 16 are assembled together to form the bit assembly 10 (FIG. 2). The bit holder body 18, shank 20, bore 40, front end 66, and base block bore 70 of base block 16 are axially aligned when assembled together to form the bit assembly 10. The shank 20 extends beyond a rearward face 72 of the base block 16 so that the annular groove 58 can be engaged by the bit retainer 62.

The legs 74, 76 of the bit retainer 62 are fitted into the annular groove 58 of the shank 20. The thickness 82 of the bit retainer 62 is less than the axial length 60 of the shank 20 such that the legs 74, 76 can slidably engage the annular groove 58 until the arcuate portion 84 becomes engaged with a complementarily-shaped portion of the annular groove 58. The bit retainer 62 has an outer dimension larger than the diameter of the portion of the base block bore 70 extending through the rearward face 72 of the base block 16. Once fully engaged and assembled, the bit retainer 62 retains the bit holder 14 within the base block bore 70 of the base block 16.

While the present disclosure has been described in connection with certain embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiments but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the scope of the appended claims, which scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures as is permitted under the law.