Woodworking – Process – Timber harvesting or processing
Reexamination Certificate
2000-05-05
2001-04-10
Bray, W. Donald (Department: 3725)
Woodworking
Process
Timber harvesting or processing
C144S208100
Reexamination Certificate
active
06213178
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to methods and apparatus for handling logs to be debarked.
BACKGROUND OF THE INVENTION
In the pulp and paper industry, logs are generally debarked before chipping. With some of logs which are to be used as raw material, the bark adheres very tightly to the logs or the bark is easily loosened as larger pieces, so that normal drum debarking is not fast enough, or in some cases discharging of the bark creates a problem. Particularly in connection with many tropical wood species, such as acacia and eucalyptus, the drum debarking method becomes problematic, as the long barks create problems by forming “bark balls” in the drum. The bark of acacia and eucalyptus also tends to loosen as long strips, so that the fresh bark also requires pretreatment, in order to avoid problems after contact with the drum. The long waste barks are not easily discharged through the bark slots of the drum and tend to come out along with the logs to the feeding conveyor of the chipper. In some cases, the drum debarking has also proven to be inefficient for the debarking of birch.
Other methods than drum debarking are used for debarking logs. A disadvantage of those methods is, however, their small capacity, which thus requires several debarking lines and a great number of devices. One known method of this kind is described in U.S. Pat. No. 4,685,498 of Fuji Kogyo. In this patent, the logs are transported through a channel-formed section in the longitudinal direction. On the bottom of the trough-shaped section, there are rollers disposed in longitudinal direction. When the rollers rotate, their teeth rasp the bark from the surface of the log.
In addition, debarking devices equipped with moving bottom elements have been tested. It has been shown in tests that a debarking apparatus shown in accordance with patent Finnish Patent No. 29866 does not rotate the logs efficiently enough, because the push force of the feed motion of the moving elements transferring the logs is not sufficiently stronger than the corresponding force in the reverse motion.
Periodically operating pretreatment devices are also being developed, the biggest disadvantage thereof being the constant need for supervision.
One such method is to break the surface of the bark with a high-pressure water jet. In such a procedure, however, a further method is also required in order to finally remove the bark. A known log pretreatment method of this type has been described in U.S. Pat. No. 4,180,109. In order to achieve the required water pressure, a strong pump is needed in this method. In addition, there are extreme requirements for the purity of the water so utilized.
SUMMARY OF THE INVENTION
In accordance with the present invention, these and other objects have now been realized by the invention of a method for removing the bark from logs comprising transporting the logs in a longitudinal direction, cutting the surface of the logs as they move in the longitudinal direction by means of blades projecting upwardly with respect to a bottom surface on which the logs are supported and which is moving in a transverse direction under the logs, and simultaneously causing the logs to move so that the logs alternately contact the blades and are displaced from contact with the blades. In a preferred embodiment, the method includes moving the blades in the transverse direction under the logs by swinging the bottom surface back and forth in the transverse direction.
In accordance with one embodiment of the method of the present invention, causing the logs to move comprises alternately contacting the logs with the blades and displacing the logs from the blades by alternately moving the blades from a location above the bottom surface to a location below the bottom surface. In a preferred embodiment, the method includes moving the logs in a first transverse direction when the blades are at a location above the bottom surface and rolling the logs in a second transverse direction opposite to the first transverse direction when the blades are at a location below the bottom surface.
In accordance with another embodiment of the method of the present invention, causing the logs to move comprises alternately contacting the logs with the blades and displacing the logs from the blades by providing an elevated portion projecting from the bottom surface, and comprising the elevated portion causing the logs to move in a first transverse direction when the logs are in contact with the blades and carrying the logs on the elevated portion in a second transverse direction opposite to the first transverse direction when the logs are displaced from contact with the blades.
In accordance with the present invention, apparatus has also been provided for removing the bark from logs comprising transporting means for transporting the logs in a longitudinal direction, a bottom surface for supporting the logs, and blade means projecting upwardly with respect to the bottom surface in a transverse direction for cutting the surface of the logs as they move in the longitudinal direction, the bottom surface including a bottom surface portion, the blade means disposed at a level below the bottom surface portion for at least some of the time that the apparatus is being operated. In a preferred embodiment, the bottom surface is movable back and forth in the transverse direction.
In accordance with one embodiment of the apparatus of the present invention, the bottom surface is inclined at a predetermined angle in the transverse direction, the bottom surface including a first end and a second end, the first end being higher than the second end, and including movable transverse beams carrying the blade means, whereby when the movable transverse beams are moving toward the first end of the bottom surface, the blade means are disposed at a level above the bottom surface, and when the movable transverse beams are moving toward the second end of the bottom surface, the blade means are disposed at the level below the bottom surface. In a preferred embodiment, the blade means include a substantially perpendicular edge facing the first end of the bottom surface thereby providing a pushing surface for moving the logs.
In accordance with another embodiment of the apparatus of the present invention, the apparatus includes an elevated surface movable with the bottom surface, the elevated surface being displaced above the blade means. In a preferred embodiment, the apparatus includes a plurality of stationary surfaces displaced longitudinally along the bottom surface and alternately projecting from below the elevated surface in a first transverse direction and a second transverse direction opposite the first transverse direction as the elevated surface moves back and forth in the transverse direction.
In accordance with one embodiment of the apparatus of the present invention, the apparatus includes at least one stationary longitudinal wall dividing the apparatus into at least two parallel sections.
In accordance with another embodiment of the apparatus of the present invention, the apparatus includes moving means for moving the bottom surface back and forth in the transverse direction, the moving means including a synchronizing shaft disposed in the longitudinal direction, crank means attached to the synchronizing shaft, and link means connecting the crank means to the bottom surface. In a preferred embodiment, the apparatus includes a stationary frame, and support means attached to the synchronizing shaft and link members connecting the support means to the stationary frame, whereby motion of the synchronizing shaft in the longitudinal direction is prevented.
In accordance with the method of the present invention, the debarking blades and the logs are moved in relation to each other, so that part of the time the logs are above the cutting edges of the blades, out of contact with the blades, and part of the time the logs are in contact with the cutting edges of the blades. The blades can be moved and the logs rotated in the transverse direction of the logs
Aronen Tero
Jonkka Arvo
Liljeroos Kari
Bray W. Donald
Lerner David Littenberg Krumholz & Mentlik LLP
Valmet Woodhandling Oy
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