Cutter Disc

Heretofore cutting discs for tree stumps or the like have required a plurality of different bit holders and differently shaped bits resulting in an expensive piece of equipment for which it is difficult to stock replacement parts, as a large supply is required where there are a large number of different parts required.

The tool holder of U.S. Pat. No. 3,797,544 has the problem of requiring special tooling to fabricate the half sections comprising the tool holder.

The cutter disc of this invention includes a plurality of cutter tools on opposite sides of the cutting disc arranged in a spiral fashion. Except for bits extending parallel to the plane of the disc, the other bits extend either inwardly or outwardly relative to the disc. These bits all use the same bit holder. It is only necessary to rotate the bit holder 180.degree. about its own center axis to provide the desired angular position.

The versatility of this bit holder is the result of utilizing a bit holder having half sections which include aligned and mating channel-shaped slots in the clamping faces of each half section. The clamping action occurs as a result of the effective depth of the slot being less than the thickness of the bit shank, resulting in the base walls of the slots bearing against the adjacent shank surfaces.

A pair of bolts extend transversely through the half sections on opposite sides of the bit shank and extend through the disc to connect another bit holder onto the opposite side of the disc.

When utilizing the universal bit holder of this invention, it is not necessary to have a large variety of different bit holders or bits, since only one is required for the angularly-disposed bits. The bits which are positioned in a straight manner on the disc utilize a holder having a slot cut in one face to receive the bit shank, and the holder is then bolted onto the disc or onto a spacer between the holder and the disc. In all cases, the same bit is used.

Fabrication of the bit holder of this invention is particularly efficient and inexpensive due to the fact that bar stock may be used. The steps of fabrication include cutting the bar stock to length, placing the cut pieces in a jig at an appropriate angle such that the slots may be cut by the rotary cutter on a milling machine. Next, the pair of holes are drilled. One quarter of the half sections are provided with countersunk holes for the heads of the bolts, while another quarter are threaded. The remaining half of the half sections require no further machining.

This invention consists in the construction, arrangements and combination of the various parts of the device, whereby the objects contemplated are attained as hereinafter more fully set forth, specifically pointed out in the claims and illustrated in the accompanying drawings in which:

FIG. 1 is a fragmentary side elevation view of a stump cutting machine employing the cutting disc of this invention.

FIG. 2 is an enlarged-in-scale side elevational view of the cutting disc.

FIG. 3 is a perspective view of the cutter tool.

FIG. 4 is a cross-sectional view taken along Line 4--4 in FIG. 2.

FIG. 5 is a cross-sectional view taken along line 5--5 in FIG. 2.

FIG. 6 is a cross-sectional view taken along Line 6--6 in FIG. 2.

FIG. 7 is a cross-sectional view taken along Line 7--7 in FIG. 2.

FIG. 8 is a cross-sectional view taken along Line 8--8 in FIG. 2.

FIG. 9 is a cross-sectional view taken along Line 9--9 in FIG. 2.

FIG. 10 is a cross-sectional view similar to FIG. 9 but includes a spacer on the right-hand side.

FIG. 11 is a cross-sectional view taken along Line 11--11 in FIG. 9.

FIG. 12 is a cross-sectional view taken along Line 12--12 in FIG. 11; and

FIG. 13 is a cross-sectional view taken along Line 13--13 in FIG. 2.

The cutter disc of this invention is referred to in FIG. 1 generally by the reference numeral 10 and is seen mounted on a stump cutting machine 12 operating on a stump 13.

The disc 10 is circular in shape and includes a center axis of rotation 14 through a center shaft 16. A plurality of cutter tools 18 are mounted on opposite sides 20 and 22 of the disc 10 as seen in FIGS. 3 and 7. The cutter tools on each side of the disc 10 define two spirals starting at the outer peripheral edge of the disc and ending adjacent and on opposite sides of the center rotational axis 14. Thus, it is seen that the disc 10 is balanced on each of its sides, and one side is balanced relative to the opposite side.

The cutter tool 18, as seen in FIG. 3, includes a pair of inner and outer half sections 26 and 28 rectangular in cross section and having opposed mating faces 30 and 32 which are parallel to each other and parallel to the disc 10. A slot or U-shaped channel 34 having a bottom side wall 36 and oppositely disposed parallel side wall surfaces 38 extends diagonally across the half section along the transverse center line thereof. The exterior end slots of the half sections 26 and 28 are identical and thus, the bottom walls of the slots are parallel to each other but extend at an angle to the disc and to the mating faces 30 and 32 of the half sections.

A bit 40 having a cutting head 42 and a shank 44 is positioned with the shank 44 in the slots 34. A pair of bolts 46 extend through the half sections 26 and 28 on opposite sides of the bit shank 44 and draw the half sections into clamping engagement with the shank 44 to hold it firmly in place. The shank 44 is rectangular in cross secton and has a thickness slightly greater than the effective depth of the slots 34 (measured perpendicularly to the bottom wall 36) such that clamping action results between the holder half sections 26 and 28 when drawn together by the bolts 46. It is further seen in FIG. 7 that the bolts 46 have heads received in countersunk holes 47 in half section 26 and then extend through a tool holder 18 on the opposite side of the disc 10 and threadably engage the openings 50 in the outer half section 26'. The half sections 26 and 26' differ only in that half sectiion 26 has countersunk openings for the bolt heads and the half section 26' has the threaded openings 50.

The bits 40 may be positioned on the disc 10 to extend inwardly towards the disc as seen in FIGS. 5 and 8, wherein the holders 18A position bits 40 to extend at an angle towards the disc 10. The same holder half sections 26 and 28 are employed but the holder 18 is simply rotated 180 degrees about its own axis and the bit 40 is reinserted in the opposite end of the slot 34.

In FIG. 12 it is seen that the thickness of the bit shank 44 is just sufficient to maintain a spacing 60 between the inner surfaces 30 and 32 on the half sectons 26 and 28.

In order that complete cutting action of the stump 14 be provided, bits 40 are positioned in a plane parallel to the disc 10. A holder 70 (FIG. 13) is utilized which is similar to the holder half section 26 and has an inner clamping face disposed in a plane parallel to the face 20 of the disc 10 and, accordingly, the slot 34 for the bit 40 is also arranged parallel to the disc face 20.

In FIGS. 9 and 10, the bits 40 arranged parallel to the disc 10 are spaced therefrom by a spacer 72 to give a more complete cutting action.

Thus, in operation it is seen that all of the cutter tools utilize the same bit 40 and all of the angularly disposed bits are held by a common holder including an outer half section 26 or 26' and an inner spacer half section 28, whereas all bits that are arranged parallel to the disc 10 are held by a holder 70 and flat washer-like spacers 72 may or may not be utilized. All that is required to change the angle of the bit 40 from extending away from the disc 10 to an angle extending toward the disc 10 is to rotate the holder 18 180.degree. and reinsert the bit in the opposite end of the slot 34. Accordingly, a minimum number of component parts need to be kept in stock for repair purposes, and when repair is needed a given bit may be easily replaced by loosening the two bolts 46 and allowing the bit to readily drop out of the slot 34. The cutting head on the bit functions as a depth limiting shoulder and is adapted to engage the outer edge of the holder whereby the bits may be positioned in the holders at a uniform depth.

The steps of fabrication for the bit holders in quantity includes taking bar stock material 1 .times. 13/4 inch and cutting it to a length of 23/4 inches. The cut pieces, rectangular in cross section, are now put in jigs which hold them at an angle such that the rotary cutter of a milling machine passing over the cut pieces forms a slot on the transverse centerline of the pieces. The slot will extend diagonally across the cut pieces. Next, two mounting holes are drilled on opposite sides of the slots, and one quarter of the pieces are provided with threads, while another quarter are provided with countersunk holes for the heads of the mounting bolts. The remaining half of the tool holder half sections require no further machining. Thus, it is seen that the holders may be fabricated quickly and at a minimum cost, but yet will provide effective holding action for the bits on the cutter disc.