AU714762B2 - An apparatus for debarking logs - Google Patents

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT Name of Applicant: Actual Inventor: Address for Service: JOHN HILE As Above CULLEN

CO.,

Patent Trade Mark Attorneys, 240 Queen Street, Brisbane, Qld. 4000, Australia.

AN APPARATUS FOR DEBARKING LOGS Invention Title: Details of Associated Provisional Applications: Nos. PN6303 The following statement is a full description of this invention including the best method of performing it known to me: This invention relates to an apparatus for debarking logs and particularly relates to an apparatus having an improved log rotating and feeding mechanism.

Log debarking machines are known in the art.

These known machines typically have a debarking station and some form of log feeding means to feed the logs into the debarking station.

Known debarking machines use chipping tools to remove the bark from logs, or rotating chain systems commonly called chain flails. The chain flail system typically comprises a rotating elongate drum member to which linked chains are attached. The drum member rotates at speed causing the chains to strike the log and therefore remove the outermost layer of bark.

15 Conventional log debarking machines suffer from a number of disadvantages, principally their relatively high cost of manufacture and their high energy requirements. For instance, existing log debarking machines require up to 150hp and cost between AU$150,000 to AU$200,000 Existing log debarking machine suffer from a number of additional disadvantages. For instance, one type of known machine has a debarking station comprising a cutting head which moves about the log. The log does S 25 not rotate and is pushed through the debarking station and the bark is removed from the cutter which rotates about the log. This cutting arrangement is cumbersome and expensive to operate. The log also needs to be accurately centralised to ensure efficient debarking.

Another type of log debarking machine has a debarking station which does not rotate about the log and where instead, the log rotates about its longitudinal axes as it is pushed through the debarking station. The debarking station can include cutting heads or a chain flail system.

Both above known devices (that is having the rotating cutting head or the stationary cutting head) still require the log to be pushed through the debarking station. Conventionally, this has been done using a long carriage on which the log is laid, and where the carriage is driven or winched through the debarking station.

However, the carriages themselves are expensive and must be sufficiently long to accommodate the longest log to be debarked.

One other known arrangement has a sliding carriage on which are mounted a number of opposed wheels on which the log is supported. The wheels are at right angles to the log and are rotated to cause the log to rotate about its longitudinal axes. The carriage is then pushed through the debarking station with the log being rotated thereon.

Another known arrangement attempts to do away 15 with the carriage system by having a non-rotating log which is fed through a debarking station by being thrust between a pair of opposed thrust wheels. The wheels counter-rotate about an axis which is at right angles to the longitudinal axis of the log such that the wheels provide a forward thrusting action, but do not rotate the S* log.

log* The present invention has been developed to provide a log debarking apparatus which may overcome the abovementioned disadvantages or provide the consumer with 25 a useful or commercial choice.

In one form, the invention resides in an apparatus for debarking logs, the apparatus comprising a debarking station and a log rotating and feeding means to rotate a log about its longitudinal axis and to feed the log towards the debarking station, the log rotating and feeding means comprising opposed rotatable members adapted to contact a said log therebetween and contacting the log at an angle to impart a forward thrust to the log as well as rotating the log about its longitudinal axis.

Having the above feeding means, allows a log to be rotated and moved through the debarking station without requiring any sliding carriages and the like.

The debarking station may comprise a chain flail system. The system may include a rotating core member, such as a drum, to which one or more line members are attached. The line members may comprise link chains, metal cables and the like. If a chain flail system is used, it is preferred that the axles of rotation of the chain flail system is in line with the longitudinal axis of the log to be debarked.

If desired, the chain flail system, or other type of debarking means, may locate within a protective housing or shroud.

The distance between the cutting arrangement on the debarking station, and the outer periphery of the log may be adjustable. This minimises damage or adverse wear and tear on the cutting arrangement should the logs be S. 15 angled, warped, or have protuberances thereon.

In one form, the adjustments may be in the form of a balance arm on which the debarking station is positioned. The balance arm can be moved to adjust the distance between the cutting arrangements in the debarking station and the outer periphery of the log.

The opposed rotatable members on the log rotating and feeding means may be sufficiently spaced apart to support a log for forward movement and rotation entirely between the rotatable members. Alternatively, additional support such as a slide member may be used.

In one form, the opposed rotatable members may comprise opposed pairs of wheels. The wheels may be mounted for rotation on a supporting frame work. A plurality of pairs of wheels may be positioned in substantial linear alignment to allow a log to be supported along its length.

For simplicity sake, it is preferred that pairs of wheels are coupled together by an axle and that adjacent pairs of wheels are also coupled to each other.

In this manner, a single drive means can be employed to drive all the wheels rather than requiring separate drive means.

In a variation, the opposed rotatable members may comprise opposed helical screws between which a log can be positioned.

The rotatable members, upon rotation, will cause a log to be rotated about its longitudinal axes.

By having the rotatable members at an angle relative to the log, a forward movement or thrust is also imparted to the log. Thus, the rotatable members provide a dual function of rotation and forward movement.

An embodiment of the invention will be described with reference to the following drawings, in which: Figure 1 show a view of part of an apparatus according to an embodiment of the invention; Figure 2 shows a plan view of the apparatus of 15 Figure 1; Figure 3 is a side view of an adjustable debarking station; and Figure 4 is a plan view of Figure 3.

Referring to the drawings and initially to Figure 1, there is shown an apparatus 10 for debarking S* logs. Figure 1 for the purpose of illustration shows a ***log of larger diameter 11 and a log of smaller diameter 12 illustrating that the apparatus can be used with logs of varying diameters.

S: 25 The apparatus has a debarking station 13, and a feeding means 14 to rotate a log about its longitudinal axes and to feed the log towards the debarking station.

Turning initially to debarking station 13, the debarking station in the embodiment comprises a chain flail system. The chain flail system has a rotatable drum member which can be between 300mm to 650mm long and which can be suspended under or over the log. It is preferred however that the flail head is suspended over the top of the log.

The chain flail drum has a number of linked elongate chain members, or wire cables which are fixed to the drum and which hit the log upon rotation of the drum.

Obviously, the longer the linked chain, the larger will be the speed at the tip of the chain. A very high tip speed is not desirable as it can unduly damage the log, damage the chain or create unnecessary wear and tear on the chain and can also reduce the debarked particles to an unusable size. Therefore, it is advantageous to ensure that the chains are a constant distance from the log. This is achieved by having the drum adjustably mounted relative to the outer periphery of the log. In one way, this is achieved by mechanical sensing wheels and also by using a longer drum so that the drum can be rotated in harmony with the direction of rotation of the log.

Beneath debarking station 13 is a conveyor system 15 to convey the bark chips along the conveyor and through an outlet 16 and into a container, truck and the *like (not shown).

The feeding means 14 in the embodiment comprises pairs of rotatable wheels which are coupled together through a rigid axle. An exemplary pair of wheels is illustrated as 17A, 17B connected by axle 18.

.".These wheels are on the input side of the debarking station 13.

On the output side of the debarking station are also pairs of wheels coupled together by axles and a further exemplary pair of wheels is illustrated as 19A, 19B coupled to axle The axles of the wheels are mounted to transverse struts 21 on a supporting framework 22. The axles are rigidly attached to the wheels such that rotation of the wheels causes rotation of the axles.

Each pair of wheels on the inlet side of the debarking station are coupled to an adjacent pair of wheels through a sprocket and chain arrangement. That is, each axle is provided with a sprocket and a chian extends over the sprocket of one axle and a sprocket of an adjacent axle.

A similar arrangement is present with the wheels on the outlet side of the debarking station.

With this arrangement, all the wheels can be driven by one motor (not shown) which can extend around one of the sprockets and by rotation of the sprocket, causes each of the wheels to rotate. The wheels of the inlet side and of the outlet side of the debarking station all rotate in the same direction.

As illustrated in Figure 1 and more clearly illustrated in Figure 2, the wheels are angled relative to the longitudinal axes of the logs (see for instance 11 and 12). Rotation of the wheels therefore causes the logs to rotate either clockwise or anticlockwise (depending on the wheel rotation). By having the wheels angled towards the debarking station in the inlet side and away from the debarking station on the outlet side, *15 the logs as well as being rotated are also pushed or thrust through the debarking station.

In the debarking station 13, the logs are not subject to any forward thrusting movement, and therefore the logs should be long enough such that a log passing through debarking station 13 is gripped by the wheels on the outlet side before the log loses contact with the last pair of wheels adjacent the inlet side. (Of course, feeder wheels could be provided in the debarking station if required).

25 It is found that the wheels can be rotated at about 3h rpm which will cause the logs to move through the debarking station at about 3-4 metres per minute.

The drive motor to drive all the wheels can be of relatively low power and typically a drive motor of between 20-30hp is sufficient. The apparatus can take logs of varying diameters from between 100mm to perhaps 1 metre or more in diameter. This is in contrast to other existing debarking machines which tolerate only small variations in a log diameter before manual adjustments have to be made.

The wheels can be pneumatic wheels having a rubber tyre. The pneumatic wheels can have a degree of flexing to accommodate undulations in the log. By having 8 tyres and especially rubber tyres, a good grip is provided on the log to drive into and from the debarking station. If desired, antiskid or grip enhancing profiles may be provided on the wheels to firmly position the log.

Referring to Figures 3 and 4, there is illustrated a side view and plan view of the debarking station. Debarking station 13 comprises a protective shroud or cover 30 in which is located the chain flail system comprising a central rotatable flail drum 31 and a number of spaced flail chains 32 attached to the periphery of drum 31. Drum 31 is positioned above a log S.11 and is spaced above the outer surface of log 11 such that the chain flails 32 can efficiently remove the outer bark layer from the log. Due to problems with a fixed 15 drum and crooked logs, figure 3 shows an adjustable system which allows the drum to float above or over the top of the log. Thus, log 11 when it passes through debarking station 13 is guided by steel guide rollers 33.

the debarking station, log 11 is also supported by a trough shaped recess 35 in a lower hopper 34.

Drum 31 is journalled or otherwise supported for rotation either by shroud 30, or a pair of extending framework arms 36, 37 (better illustrated in Figure 4).

*Framework arms 36, 37 form part of a frame assembly which 25 also includes cross members 38A, 39A and 40A to provide a rigid frame assembly.

Drum 31 is rotated by a motor 38 having an output shaft 39 connected to a pulley 40 about which a band or chain 41 extends which extends about a pulley 42 connected to drum 31. Motor 38 is supported by frame arm 36.

The entire frame assembly comprising frame arms 36, 37 is mounted for pivoting movement about a pivot point 43. Thus, the entire frame assembly and therefore drum 31 together with its shroud 30 can move up and down about pivot point 43. This movement is achieved by a pneumatic ram 44 which lifts or lowers the frame assembly.

9 An adjustable arm 45 is attached to frame arm 36 and terminates in a roller 46. The adjustable arm therefore senses the distance between the log and the drum. The adjustable arm can be preset adjusted or reset to ensure the required spacing is maintained between the log and the drum 31. The spacing is calculated to maximise the efficiency of bark removal.

In use, as a log enters the barking station 13, a sensor activates the pneumatic ram to lift the frame arms and thus the drum above the log. 1 seconds later, air is released from the pneumatic ram 44 to allow the arrangement to slowly come down under gravity until adjustment arm 45 contacts the log.

The apparatus according to the invention has a 15 simple yet reliable construction. The machine has minimal power consumption and can handle difficult variations in the logs. The machine can debark logs that are notoriously hard to remove bark from, and it has been found that cypress logs can be efficiently debarked by the machine. The machine produces a partially refined product which is highly regarded in use for plant nurseries.

It should be appreciated that various other changes and modifications may be made to the embodiment without departing from the spirit and scope of the invention.

Claims (12)

1. An apparatus for debarking logs, the apparatus comprising a debarking station and a log rotating and feeding means to rotate a log about its longitudinal axis and to feed the log towards the debarking station, the log rotating and feeding means comprising opposed rotatable members adapted to contact a said log therebetween and contacting the log at an angle to impart a forward thrust to the log as well as rotating the log about its longitudinal axis, the rotatable members being in the form of opposed pairs of wheels, each pair of wheels being mounted to a common axle, the axle of one pair of wheels and lo the axle of the opposed pair of wheels being parallel relative to each other and inclined to the feed direction of the log, the opposed wheels being offset relative to each other.

2. The apparatus of claim 1, wherein the debarking station comprises a chain flail system. 15

3. The apparatus of claim 2, wherein the system includes a rotating oooo° core member, such as a drum, to which one or more line members are attached.

4. The apparatus of claim 3, wherein the one or more line members comprise link chains or metal cables.

5. The apparatus of claim 4, wherein a link chain is used and the axis of rotation of the chain flail system is parallel with the longitudinal axis of the log to be debarked.

6. The apparatus of any one of claims 2 to 5, wherein the chain flail a system, or other type of debarking means locates within a protective housing or shroud.

7. The apparatus of any one of the preceding claims, wherein the distance between the cutting arrangement on the debarking station, and the outer periphery of the log is adjustable.

8. The apparatus of claim 7, wherein the adjustment is in the form of a balance arm on which the debarking station is positioned, the balance arm S- being moveable to adjust the distance between the cutting arrangements in the debarking station and the outer periphery of the log.

9. The apparatus of any one of the preceding claims, wherein the opposed rotatable members on the log rotating and feeding are sufficiently spaced apart to support a log for forward movement and rotation entirely between the rotatable members.

The apparatus of claim 9, wherein additional support such as a slide member is used.

11. The apparatus of any one of the preceding claims, wherein the pairs of wheels are coupled together by an axle and that adjacent said pairs of wheels are also coupled to each other.

12. An apparatus substantially as hereinbefore described with reference to the accompanying drawings. DATED this 10 th day of November 1999 John HILE By his Patent Attorneys CULLEN CO. p p p. pp* *p p