Woodworking – Process – Mechanical cutting or shaping
Patent
1994-04-20
1995-11-28
Bray, W. Donald
Woodworking
Process
Mechanical cutting or shaping
144 3R, 144 39, 144367, 144357, 144378, B27B 100, B27C 900
Patent
active
054699045
DESCRIPTION:
BRIEF SUMMARY
The present invention concerns an apparatus for sawing a square timber, a spar or a plank, and a method for dividing a square timber, spar or plank into parts.
A person aiming to utilize timber material optimally will encounter problems, most particularly when curting up crooked logs. In such instances the usual procedure is to first turn the log so that the crook or bend points up or down, and it is dressed to become a square timber having two opposed planar surfaces, this being accomplished by running it through a saw or e.g. through a square timber hewing machine, or chipper. The crooked square timber may then be dressed to become a spar of which all side faces are dressed, by running it e.g. through a second chipper. The result hereby produced is a crooked spar, which is not necessarily uniform in thickness over its entire length, and therefore this timber cannot be sawn over its whole length to yield full-sized sawn timber.
In the interest of simplicity, this application mainly speaks of square timber when referring to (small) square timbers, spars, planks or equivalent timber goods to be processed. Another alternative is to cut the square timber with a saw directly in one work step into boards and deals. Both ways of accomplishing the task are troubled by the same problems. It is hard to rip a crooked square timber or spar into timbers of uniform thickness over its whole length because its curvature frequently varies and rotates and the thickness changes, whereby it is difficult to guide the timber to meet the saw blades in an optimal manner.
The state of art in the field of the present invention is presented in the Finnish Patents 68014, 8778 and 81985, and in U.S. Pat. No. 4,127,044. In all these pieces of apparatus described in the references, too, the problem is that cutting of the square timber, or spar, into boards and deals is not successfully managed, at least not when the curvature of the log varies and changes direction while cutting is in progress. In general, satisfactory results are only achievable with existing apparatus when the log that is being ripped is uniformly curved over its entire length.
The object of the invention is to eliminate the drawbacks just mentioned. It is specifically an object of the invention to provide a novel apparatus and procedure by the aid of which one gains from crooked logs their optimum sawn timber output, independent of curvature variations and changes of direction of the curvature in the log.
Regarding the features characterizing the invention, reference is made to the claims section.
The apparatus of the invention for cutting square timber comprises a feed mechanism, a chipper and a sawing apparatus in such manner that the feed mechanism has been arranged to feed the square timber into the chipper, the chipper is arranged to remove from the square timber its curved superficial portions, and the sawing apparatus is arranged to cut the spar emerging from the chipper into boards, deals and equivalent As taught by the invention, the feed mechanism is connected to the chipper by means of a pivot with a vertical axis, and the chipper is connected to the sawing apparatus by means of another pivot with a vertical axis, said sawing apparatus being carried on the frame of the overall apparatus. The apparatus furthermore comprises a feed table from which the square timber is fed, in controlled manner, into the feed mechanism. The apparatus likewise comprises a control unit, by the aid of which the feed mechanism and the chipper are swivelled about their pivots, both relative to each other and relative to the sawing apparatus, in accordance with the curvature of the square timber that is being processed.
In this way, in the apparatus of the invention, the chipper and the feed mechanism both follow the shape of the square timber and spar which is being cut, i.e., its curvature, and turn it along with themselves so that it will be fed into the saw blades parallelling these blades at all times. This has the effect of precluding any torsion effects on the square timbe
REFERENCES:
patent: 4139035 (1979-02-01), Bystedt et al.
patent: 4440203 (1984-04-01), stberg
patent: 4548247 (1985-10-01), Eklund
patent: 4572256 (1986-02-01), Rautio
patent: 4599929 (1986-07-01), Dutina
patent: 4881584 (1989-11-01), Wislocker et al.
patent: 5148847 (1992-09-01), Knorr
International Search Report PCT/FI 92/00279 dated Dec. 10 1992.
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