Patent Grant
6851461
This invention relates to apparatus for removing bark from raw logs, and, more particularly, to a drum type debarker with variable debarking action.
Debarking equipment for removing bark from logs prior to additional processing by other wood processing equipment is well known. Examples of prior art debarking equipment known to the inventors includes the following patents:
U.S. Pat. No. 3,190,327 to Robbins
U.S. Pat. No. 3,862,653 to Fay et al.
U.S. Pat. No. 3,863,692 to Hasada et al.
U.S. Pat. No. 4,691,750 to Nakajima
U.S. Pat. No. 4,771,953 to Morey
U.S. Pat. No. 5,070,919 to Ackerman; and
U.S. Pat. No. 5,117,881 to Simpson
Many existing designs for debarking equipment rely on a drum arrangement into which logs to be debarked are fed. The drum is mounted for rotation about a generally horizontal, longitudinal axis and the inner surface of the drum has a sequence of longitudinal flights or ridges that run parallel to the axis of rotation. As the drum is rotated, the flights act to carry the logs to an elevated position where they are dropped due to gravity to make contact with other logs and lower flights which act to remove bark from the logs by abrasion.
The rate at which logs are debarked in a drum-type debarker depends on various factors including log condition, log diameter, temperature, and log species which all affect the adherence of the bark to the underlying wood.
Conventional drum-type debarking equipment suffers from the disadvantage that it is limited in its ability to control and vary the rate of debarking. When conditions are such that bark is easily removed from a batch of logs, the residence time of the logs in the drum until the bark is removed is reduced. If a batch of logs has bark that is more difficult to remove, the residence time has to be increased. In some equipment, the drum can be rotated at different speeds. A slower rotation speed accommodates logs with easily removed bark while a faster speed tends to debark more difficult logs with approximately the same residence time.
The present invention provides debarking equipment that allows for variation in the rate of debarking by rotating the drum in different directions. The choice of rotation direction on the desired aggressiveness of debarking. When the debarking requirement is easy, the drum is rotated in one direction such that debarking is achieved in a substantially conventional manner by log to log contact and contact with the drum walls and flights. As conditions change and the bark is more difficult to remove, the drum is rotated in the opposite direction to expose an additional abrasive debarking element.
Accordingly, the present invention provides apparatus for debarking a log comprising:
a drum mounted for rotation about an axis and having a inner surface;
debarking apparatus on the inner surface configurable to debark a log within the drum at a first rate on rotation of the drum in a first direction and at a second rate when the drum is rotated in a second direction.
The debarking apparatus of the present invention preferably comprises a pivotable plate with an abrasive surface that is exposed or concealed depending on the direction of rotation. In an alternative arrangement, the debarking apparatus includes a movable cover that acts to cover or expose a fixed abrasive surface depending on the direction of rotation.
Aspects of the present invention are illustrated, merely by way of example, in the accompanying drawings in which:
a is a schematic view of different debarking plate configurations;
Referring to
Flights 12 are spaced about inner surface 10 and act to lift and drop logs introduced into drum interior 8 as the drum is rotated about axis 6. The debarking equipment of the present invention also includes additional debarking apparatus 20 on inner surface 10 configurable to debark logs at different rates depending on the direction of rotation of drum 4 as indicated by arrow 18. When drum 4 is rotated, for example, counterclockwise, logs are debarked at a first rate and when drum 4 is rotated in the opposite clockwise direction, logs are debarked at a second rate. In other words, the debarking equipment of the present invention works on the principle that a reversible drum in conjunction with debarking apparatus 20 allows the operator to vary the rate of debarking as required.
Debarking plates 22 are mounted to inner surface 10 of drum 4 and configured to allow serrated edge 24 to make contact with logs when the drum is rotated in a first direction and configured to eliminate or at least minimize the participation of the serrated edge 24 in the debarking process when the drum is rotated in a second direction as will be explained in more detail below.
Pivot pin 28 and debarking plate 22 are interconnected such that either abrasive surfaces 24 or substantially flat surface 26 of plate 22 will be rotated for exposure depending on the direction of rotation of drum 10. This pivoting action is illustrated in FIG. 4. At the upper periphery 40 of the drum, the debarking plates 22 hang generally downwardly toward the axis of rotation 6 of the drum due to gravity. The direction of rotation of drum 4 determines which way the plates pivot about pin 28 and which surface of the plate is facing upwardly and inwardly at the bottom periphery of the drum where debarking occurs. For example in the illustrated embodiment, when drum 4 is rotated in a first, counterclockwise direction as indicated by arrow 35 in
Movable plate 50 is slidable between a first position shown in
The operation of movable plate 50 is controlled by an activation system to urge the plate to the appropriate position based on the direction of rotation. In a preferred arrangement, the activation system involves weighting of the movable plate 50 to slid to the exposing or covering position due to gravity on rotation of the drum. Movable plate 50 includes a counter-weight 55 affixed to the exterior portion 58 of movable plate 50.
The illustrated embodiments of show the debarking plates 22 of the present invention positioned between conventional debarking flights 12 which act to lift and drop the logs, and which also server to debark logs that come into contact with the flights. It is intended that the debarking equipment of the present invention can be constructed without conventional flights 12. In such an arrangement, the radially inwardly extending edge surfaces 60 and the abrasive debarking surface 24 itself (when exposed) of debarking plates 22 will act as a engaging surface to lift logs with rotation of the drum for subsequent dropping to the lower periphery of the drum where the debarking action occurs.
Although the present invention has been described in some detail by way of example for purposes of clarity and understanding, it will be apparent that certain changes and modifications may be practised within the scope of the appended claims.
| Number | Name | Date | Kind |
|---|---|---|---|
| 1324193 | Guettler | Dec 1919 | A |
| 2592054 | Mertz et al. | Apr 1952 | A |
| 2712330 | Thompson | Jul 1955 | A |
| 3190327 | Robbins | Jun 1965 | A |
| 3807469 | Schnyder | Apr 1974 | A |
| 3862653 | Fay et al. | Jan 1975 | A |
| 3863692 | Hasada | Feb 1975 | A |
| 4691750 | Nakajima | Sep 1987 | A |
| 4771953 | Morey | Sep 1988 | A |
| 5070919 | Ackerman | Dec 1991 | A |
| 5117881 | Simpson | Jun 1992 | A |
| 5390866 | Kochnev et al. | Feb 1995 | A |
| 5896901 | Lacroix | Apr 1999 | A |
| 6578609 | McNicol et al. | Jun 2003 | B1 |
| Number | Date | Country | |
|---|---|---|---|
| 20040007288 A1 | Jan 2004 | US |
