US2873923A - Wood rechipper - Google Patents

Description

` Feb. 17, Al BERGMAN 2,873,923

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United States Patent O WOOD RECHIPPER Arthur Bergman, Longview, Wash., assiguor to Columbia Veneer Company, Seattle, Wash., a corporation of Washington Application July 16, 1956, Serial No. 598,041 1 Claim. (Cl. 241--280) This invention relates to a rechipper for reducing large wood chips to chips of smaller dimensions.

When making paper pulp, wood first is reduced to the form of chips which then are digested with the selected chemicals until they are converted to pulp. In this sequence, it is critical that the chips be of uniform dimensions. If they are too large, they do not digest completely in the allotted cooking period with the result that a non-uniform pulp, and hence a non-uniform paper product, is obtained.

Accordingly it is common practice to screen the wood chips produced by any of the conventional wood chippers for the removal of oversized chips. This results in the separation of from 3% to 5% of chips measuring from two to six inches in length which must be reduced further if they are to be used as a source of pulp. Their reduction is difcult of accomplishment, however, since if they are merely rerun through the original chipper, or passed through other chppers of conventional design, they pass between the knives or at best are split lengthwise so that the desired transverse reduction is not obtained. As a consequence, it is common practice to burn the oversize chips which accordingly are lost as a source of paper pulp.

It is the general object of the present invention to provide a rechipper which eiectively and economically reduces in size the oversize chips produced in the foregoing manner so that a chipped product is obtained which may be digested satisfactorily in the manufacture of paper pulp.

The manner in which the foregoing and other objects of the present invention are accomplished Will be apparent from the accompanying specification and claim considered together with the drawings, wherein:

Fig. 1 is a view in side elevation, partly in section, illustrating the construction of the herein described Wood ICC ` particular reference to the drawings;

rechipper, the sectional portion of the cutter head being as viewed toward the right in Fig. 2 from the longitudinal center line of the cutter head;

Fig. 2 is a fragmentary plan view illustrating the construction of the cutter head and anvil incorporated in the Wood rechipper of Fig. l; and

Fig. 3 is a view in side elevation of the cutter head included in the rechipper illustrated in Figs. l and 2.

Broadly stated the Wood rechipper of mylinvention comprises a cylindrical head, mounting means for rotatably mounting the head, and coupling means for coupling the head to a source of power. A plurality of knives having outwardly arcuate cutting edges are mounted obliquely on the cutter head, preferably in a V-shaped configuration. An anvil is mounted opposite the cutter head for cooperation therewith. Feeding means also are provided for feeding chips to the knives in a vertical direction. When this is done, the unique construction of the cutter head and knives results in upending the chips, and in guiding them toward the central portion of the head, where they are cut transversely into lengths suitable for pulping.

.T he herein described wood rechipper includes a cylindrical cutter head 10 keyed to a shaft 12 which is mounted for rotation in bearings 14. Shaft 12 is coupled by means of pulley 16 or other means to a suitable source of power, for example an electric motor operating at the desired rate.

A plurality of knives 20 are mounted obliquely on the cutter head. The knives preferably are shorter than the cutterhead is long and are arranged in pairs in a V -pattern as is illustrated particularly in Fig. 2. lThe knife shown lin Fig. l terminates at its right-hand end on the longitudinal center line of the head 10, and at its lefthand end at one end of the head. Thus, with the head rotating in the direction of the arrow in Fig. l, the apex of the V pattern of the pair of knives trails the lateral ends thereof. The knife edges have a contour which is outwardly arcuate and accordingly a pronounced crown is present on them.

Cooperating with the knives is an anvil 22 having a slot 24 therethrough. The working face of the anvil is angular and includes a first or guiding section 26 and a rectilinear working section 28 disposed obliquely thereto. The latter is aligned substantially with the path of travel of the knives.

Means are provided for adjusting the anvil toward and away from the cutter head assembly. In the illustrated form of the invention, the anvil is bolted to frame members 32, 34 by means of a bolt 30 which penetrates slot 24 in the anvil. A second bolt 36 is threaded into a frame member and abuts the back surface of the anvil. Accordingly, upon loosening bolt 30, the anvil may be moved to the desired position. Thereafter bolt 30 may be tightened, clamping the anvil in place. Bolt 36 then may be advanced until it is in abutment with the anvil, Where it stabilizes it and backs it up against the thrust of the cutting operation.

Means also are present for feeding material to the cutting assembly. Such means comprises a vertical hopper dened in part by a vertical plate 38, an inclined plate 40 and sidewalls 42, 44. The surface of plate 40 is substantially aligned with guiding surface 26 of anvil 22 so that chips pass smoothly down the hopper against the cutter head.

In operation, anvil 22 is adjusted so that it is in effective Working relationship to knives 20. Cutter head 10 then is set in motion at the desired rotational rate and wood pieces, for example oversize chips resulting from the action of a chipper on waste wood veneer or other raw material, are introduced into the hopper. The chips pass in a substantially vertical direction down on to the cutter head where the action of the knives first up-ends them and then cuts them transversely so that short pieces are formed.

In addition, the oblique setting of the knives works the chips toward the central portion of the cutter head so that they are not passed between the ends of the head and the sidewalls of the apparatus. As a consequence the chips are reduced effectively to smaller chips suitable for cooking in a Wood pulping operation in the usual manner.

It is to be understood that the form of my invention herewith shown and described is to be taken as a preferred example of the same and that various changes in the shape, size and arrangement of the parts may be resorted to without departing from the spirit of my invention or the scope of the subjoined claim.

Having thus described my invention, I claim:

A wood rechipper comprising a cylindrical head, head mounting means for rotatably mounting the head, coupling means for coupling the head to a source of power, anvil means stationed adjacent the head a spaced distance therefrom and having a rectilinear Working section arranged parallel to and above the horizontal axis of the head, a plurality of knives mounted on the head in a transverse V shape with the apex thereof trailing the side edges in the direction of rotation of the head, the cutting edges of the knives being defined by uninterrupted plane surfaces` and being contoured arcuately for cooperation with the rectilinear working surface of the anvil during rotation of the head, a' hopper positioned above the knives and having a wall thereof inclined downwardly toward the anvil means, and an upper guiding section on the anvil means having a surface arranged obliquely with respect to the lower working section and disposed substantially in the plane of the adjacent hopper wall.

AReferences Cited in the tile of this patent UNITED STATES PATENTS Forbes Aug. 26, 1879 Carter et al. Oct. 15, 1889 Milts et al. July 3, 1928 Pendleton Jan. 15, 1929 Becker July 10, 1951 FOREIGN PATENTS Sweden Feb. 14, 1903 Germany Apr. 5, 1886 Norway Jan. 18, 1926 Sweden Apr. 20, 1926

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