Woodworking – Rotary cutter – Disk cutter including side attached – edge cutting bit
Reexamination Certificate
2002-01-29
2003-04-15
Bray, W. Donald (Department: 3725)
Woodworking
Rotary cutter
Disk cutter including side attached, edge cutting bit
C144S024120, C144S241000, C299S079100, C299S106000, C299S107000
Reexamination Certificate
active
06546977
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a tree stump grinding apparatus for disintegrating wood material, such as a tree stump grinder.
Conventional stump grinders are disclosed in U.S. Pat. Nos. 5,279,345 and 5,497,815 for example. A typical tree stump grinder comprises a rotatable wheel having a plurality of cutting units mounted on the sides and the outer periphery of the wheel. As the wheel is rotated, the cutting units are moved into contact with the stump to gradually disintegrate the stump.
A typical cutting unit employed at the outer periphery of the wheel includes a holder (or block) secured to the wheel and a tooth (or bit) mounted in the block. The bit comprises a steel shaft carrying a carbide tip. The blocks are configured so that the bits are inclined at various angles relative to the wheel.
During use of a typical stump grinder, the outer peripheral edge of the wheel is subjected to considerable wear by the cuttings, since the cuttings from the peripheral cutting units (e.g., soil, rocks, wood, etc.) will impact against the outer peripheral edge of the wheel and the blocks. Such wear can significantly shorten the life of the apparatus.
Another problem involves premature breakage of the peripheral cutting bits. It has been common to use bits that are stationary (i.e., non-rotatable) with respect to their respective blocks and whose carbide tips have a flat front face that forms an elongated cutting edge to efficiently shave cuttings from stumps. However, it has been found that such cutting edges are particularly susceptible to being broken upon impacting against rocks embedded in soil surrounding a stump being worked on. Accordingly, many operators have switched to bits having pointed (conical) tips and which are freely rotatable in their blocks. The pointed tips are able to break the rocks, and are essentially self-sharpening due to the bits being freely rotatable. However, those types of bits tend to pulverize and shred the stumps, rather than shaving distinct chips from the stumps, and thus do not cut stumps as efficiently as the stationary bits having elongated cutting edges.
Other shortcomings associated with conventional stump cutters include excess drag imposed on the wheel due to contact between the blocks and the material being cut. Also, since the blocks are of different configurations in order to enable the bits to be oriented at different inclinations relative to the wheel, an operator must keep a large number of blocks in inventory which is expensive and time consuming.
SUMMARY OF THE INVENTION
The present invention relates to a stump grinding apparatus which comprises a wheel that defines a center axis of rotation. The wheel includes axially spaced side surfaces and a circular outer peripheral edge. The peripheral edge defines an outer circumference of the wheel, the outer circumference having a diameter substantially larger than an axial thickness of the wheel. Recesses are formed in the outer peripheral edge, the recesses being spaced circumferentially apart. Each recess includes leading and trailing end walls spaced circumferentially apart, and a floor interconnecting the end walls. Side cutting units are mounted to and project from the side surfaces. A cutting structure is mounted in each of the recesses. Each cutting structure includes at least one peripheral cutting unit comprised of a block affixed to the floor of the recess, and a bit mounted in the block. Each bit includes a shank mounted in a hole formed in the block and a hard tip disposed at a front end of the shank. The tips project past the outer circumference of the wheel. In one aspect of the invention, each cutting structure is spaced from the leading and trailing end walls of its respective recess to form spaces between the cutting structure and the leading and trailing end walls through which cuttings may pass.
In another aspect of the invention, the bits of at least some of the peripheral cutting units are rotatable relative to their respective blocks, with the hard tips thereof being generally pointed. The bits of others of the peripheral cutting units are non-rotatable relative to their respective blocks, with the hard tips thereof forming elongated cutting edges.
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Monyak Kenneth
Paumier James
Bray W. Donald
Burns Doane , Swecker, Mathis LLP
Sandvik Rock Tools, Inc.
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