Commonwealth Scientific and Industrial Research Organisation

Ian J MacArthur

Robin Wingate-Hill

William C Gabriel

When conventional mechanical equipment for removing branches or limbs from a tree trunk is used, stumps of the branches removed remain on the tree trunk. The present invention avoids the creation of such stumps when a trunk (or a length of a trunk) is being transported through a mill or compression debarking equipment and is simultaneously rotated. The invention uses an elongate helical milling head, mounted at the end of a support arm and rotated by a motor to remove the branches. The milling head axis is positioned parallel to the axis of the trunk with the cutting surface of the milling head close to the bark of the trunk. Normally a brace member is included to stiffen the mounting of the milling head. Preferably the milling head is formed as a plurality of short milling heads mounted colinearly and with their helical cutters aligned.

Apparatus for removing branches from tree trunks

Apparatus for debarking a log using the compression debarking technique includes rollers which apply radial pressure to the log to separate the bark from the wood of the log. Three double-cone rollers, each having its double cones tapered to the middle of the roller, are arranged with their axes of rotation at substantially 60.degree. to each other and perpendicular to the direction of travel of the log through an aperture defined by the three rollers. Pressure is applied to the bark of the log by the double-cone rollers. The apparatus may include cutting means, such as a knife blade on the outer surface of all three of the double-cone rollers, which slices the bark which has been separated from the wood of the log by the pressure applied by the rollers, so that strips of bark fall from the log. The invention is especially suitable for removing thick stringy, fibrous bark from logs.

Compression log debarking apparatus

Apparatus for debarking a log using the compression debarking technique includes rollers which apply radial pressure to the log to separate the bark from the wood of the log. Pairs of rollers mounted in a bogie-like arrangement on the end of respective arms bear against the log. At each roller contact location, the log is also contacted by either a fixed roller or another pair of bogie-mounted rollers. At least two of the rollers of each set are driven by a reversible motor, to rotate the log while pressure is applied to it. The (preferably variable) angle which the planes of rotation of the rollers make with the longitudinal axis of the log ensures that the log is transported through the set of rollers as pressure is applied to the log. Cutting means, such as a knife blade on the outer surface of at least one roller, slices the bark which has been separated from the wood of the log, so that strips of bark fall from the log. The invention is especially suitable for removing thick stringy, fibrous bark from logs.

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Bungendore, Australia

Ian J MacArthur