AU733175B2 - Apparatus for removing barks from a flow of timber containing wood and bark - Google Patents

Description

Apparatus for removing barks from a flow of timber containing wood and bark The present invention relates-to an apparatus for removing barks from a wood- and bark-containing flow of timber to be fed into the apparatus.

In view of the quality of pulp, it is important that the amount of barks ending up in chipping along with tree trunks be kept as small as possible. Stripping the bark off the surface of tree trunks is usually carried out in a barking drum, wherein the relative motion and attrition of tree trunks result in the bark peeling off the surface of tree trunks. The loose finely crushed bark falls mostly through the bark openings of the drum onto a bark conveyor set below the drum. However, the loose bark removed in the form of long strips or large sheets strives to come out of the discharge end of the barking drum along with tree trunks. Such hard-to-bark trees include several species of hardwood, such as eucalyptus, acacia, hickory, and birch.

If the discharge end of a barking drum turns out bark entangled with logs and in the form of individual strips or bark balls (bark balls in this context refer to a heap consisting of more or less intertwined barks, possibly containing also pieces of wood, slivers or the like), the removal of most of said bark is o ."endeavoured prior to chipping or other such treatment of the logs. Partial stripping of bark can be effected by means of a purposely designed roller i' system. However, the bark balls and some of the long bark strips are difficult 25 to remove by means of a roller system; a moderatelyclose-spaced, timber (pieces of wood) conserving roller system tends to leave almost the entire S: bark ball and some of the loose barks in the flow of timber, whereas a wide- 0spaced roller system removes most df the loose barks and even some of the 0' bark balls but results simultaneously major losses of timber.

*oThe Applicant's earlier patent Fl 76511 discloses an apparatus as described oo*o above for removing barks. Operation of the apparatus is based on a roller system, including studded rollers and smooth-surface rollers, which are vertically staggered relative to each other and wherein, furthermore, a smooth roller set between two studded upper rollers is located closer to the upstream studded roller than to the downstream studded roller for dropping the barks through this wider gap onto a s conveyor below. The apparatus is primarily intended for the removal of short barks. The removal of material containing long barks and especially bark balls is more difficult to handle with this type of apparatus.

Object of the Invention It is an object of the present invention to overcome or ameliorate some of the disadvantages of the prior are, or at least to provide a useful alternative.

Summary of the Invention In a first aspect, the present invention consists in an apparatus for removing barks from a wood- and bark-containing flow of timber to be fed into the apparatus wherein the apparatus includes at least one shake roller, designed as part of a conveyor carrying a flow of timber, and a number of rotatable rollers, set downstream thereof below a plane of motion defined by said conveyor, crosswise to a moving direction of the flow of timber, for providing the conveyor with a bay.

In one preferred embodiment of the apparatus, the shake roller subjects the timber to a vibrating action, the barks and bark balls entangled in timber falling either directly between the rollers and thence further onto a conveyor or the like below or ending up in a bay included in the apparatus of the invention and thence further through the rollers, by virtue of the relative motion thereof, onto a bark conveyor or the like.

In further preferred embodiments of the invention, the arrangement is such that the bay is constituted by one or more smooth rollers and orie or more profiled rollers. In OO, 25 this context, the term smooth roller indicates that the roller has a cross-section which is throughout essentially circular. Respectively, the term

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S S S **S [R:LIBLL08640.doc:Izn profiled roller indicates that the roller surface is provided with projections, such as gripping bars, studs or teeth.

In view of enhancing and facilitating the removal of barks, the arrangement in one preferred embodiment of the invention is such that the smooth rollers and the profiled rollers have a peripheral speed and a rotating direction adapted to be selected independently of each other. The most preferred arrangement is such that the smooth rollers have a peripheral speed which is varied as desired and a rotating direction which is possibly even reversible with respect to that of the profiled rollers. By virtue of these actions, the advancing movement of bark at the smooth-surfaced wheel can be momentarily slowed down, whereby the studs or the like gripping elements of the profiled rollers have more time to work for the removal of barks and for dropping the same through the rollers onto a conveyor below.

The invention will now be described in more detail by way of an example, with reference made to the accompanying drawing, in which: Fig. 1 Fig. 2 shows an apparatus of the invention in a schematic plan view.

shows a section along a line I1-11 in fig. 1.

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0, 000 The apparatus of the invention, shown schematically in the drawing, is designed toremove as effectively as possible the barks and bark balls from a wood- and bark-containing flow of timber to be fed into the apparatus, yet at the same time to effectively eliminate a loss of wood as a result of wood material discharging along with the barks.

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304 017@ Fig. 1 shows the apparatus in a schematic plan view and fig. 2 respectively in a schematic side view.

The apparatus includes at least one shake roller 1, designed as part of a conveyor carrying a flow of timber, and a number of rotatable rollers 2, 3, set downstream thereof below a plane of motion 5 defined by said copnveyor, crosswise to a moving direction A of the flow of timber, for providing the conveyor with a bay 4.

Fig. 2 illustrates an apparatus of the invention in solid lines and to the left thereof is a feed conveyor 6 drawn in dashed lines for moving a flow of timber and to the right thereof, also drawn in dashed lines, is another apparatus of the invention, and to the right of that is a conveyor, now shown, for carrying the flow of timber further. If necessary, the apparatus of the invention shown in dashed lines can be replaced with the latter conveyor. The number of successively arranged pieces of apparatus of the invention between the conveyors can be selected arbitrarily according to how completely the barks and bark balls must be removed from a flow of wood.

A preferred apparatus of the invention is provided with a bay 4, which is constituted by one or more smooth rollers 2 and one or more profiled rollers 3. In this context, the smooth roller 2 refers to a roller which has a substantially circular cross-section. However, the roller need not be of a uniform thickness but can be providedwith a number of bulges, as depicted in the drawing.

20 Respectively, the profiled roller 3 is provided with radially extending projections, e.g. gripping bars and studs.

In the illustrated example, the bay 4 has a floor which comprises three profiled rollers 3 and three smooth rollers 2, the profiled rollers 3 and the smooth rollers 2 alternating with each other. To the right of the rollers 2, 3 constituting the actual bay 4 is yet another profiled roller 3a, which is coo tnagential to a plane of motion 5 of the conveyor. Between the shake roller 1 and the feed conveyor 6 is a profiled roller 3b, which is likewise tangential to the plane of motion The shake roller 1, smooth rollers 2, and profiled rolers 3, 3a, 3b are conventionally joumalled at the ends thereof to the frame elements of the apparatus.

The shake roller 1 is provided with its own source of power (not shown), whereby the roller 1 has a rotating speed which is independently adjustable.

In the illustrated example, the roller 1 comprises a shaft, having a uniform thickness and a circumfential surface which is provided with spaced-apart discs or the like, whose circumference is in turn provided with one or more radial projections for shaking a tree trunk as the roller 1 is rotating.

At the end of each smooth roller 2 is a sprocket 7, the rollers 2 being connected to each other by means of a chain 8 and provided with a common source of power (not shown) for driving the rollers 2.

At the end of each profiled roller 3, 3a, 3b is likewise a sprocket 9, the rollers 3, 3a, 3b being connected to each other by means of a chain 10 and provided with a common, separate source of power (not shown) for driving the rollers 3, 3a, 3b.

Unlike the above-described and illustrated solution, another possible arrangement is such that all rollers whether profiled 3, 3a, 3b or smooth 2 can be driven in smaller groups, even individually, by providing a necessary 20 number of power sources.

Thus, the peripheral speed and rotating direction of the smooth rollers 2 and those of the profiled rollers 3 can be selected independently of each other. In practice, the rotating direction as well as the peripheral speed of the profiled 25 rollers 3 lining the bay 4 are as a rule maintained consistent with the moving le direction A of a flow of wood. A principal exception to this rule is the roller 3 *ooo.

closest to the shake roller 1 (the left-hand roller 3 in fig. whose rotating direction is reversed, whenever necessary. The peripheral speed as well as the rotating direction of the smooth rollers 2 can be varied as necessary for 30 the best possible result in terms of separating the barks.

The bay 4 has a length which in the lengthwise direction is less than the average length of tree trunks to be handled, thus increasing the vertical movement of tree ends and enhancing the falling of barks.

The bay 4 has a depth s which is at its maximum at the end adjacent to the shake roller 1. The depth S preferably exceeds the diameter of a conventional bark ball.

In the recommended exemplary embodiment of fig. 2, the depth s of the bay 4 diminishes substantially evenly in the moving direction A of a flow of wood.

The lining tangential to the smooth rollers 2 extends at a level slightly lower than the lining tangential to the profiled rollers 3.

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Claims (8)

1. An apparatus for removing barks from a wood- and bark-containing flow of timber to be fed into the apparatus, wherein the apparatus includes at least one shake roller, designed as part of a conveyor carrying a flow of timber, and a number of rotatable rollers set downstream thereof below a plane of motion defined by said conveyor, crosswise to a moving direction of the flow of timber, for providing the conveyor with a bay.

2. The apparatus of claim 1, wherein the bay is constituted by one or more smooth rollers and by one or more profiled rollers.

3. The apparatus of claim 2, wherein the smooth rollers and the profiled rollers are alternatively arranged.

4. The apparatus of claims 2 or 3 wherein the smooth rollers and the profiled rollers have a peripheral speed and a rotating direction which are adapted to be selected independently of each other. Is

5. The apparatus of any one of claims 2 to 4 wherein the smooth rollers are adapted to be driven by one or more sources of power, such that each source of power is adapted to drive one or more smooth rollers in an independently adjustable manner.

6. The apparatus of any one of claims 2 to 5 wherein the profiled rollers are adapted to be driven by one or more sources of power, such that each source of power 20 is adapted to drive one or more profiled rollers in an independently adjustable manner. So

7. The apparatus of any one of the preceding claims wherein the bay has a 0* length which in a lengthwise direction is less than an average length of tree trunks to be handled. oo*ooo

8. The apparatus of any one of the preceding claims wherein the bay has a depth which is at its maximum at the end of the bay adjacent to the shake roller. 006*0: S 09. The apparatus of any one of the preceding claims wherein the shake roller has a rotating speed which is adapted to be independently adjustable. te 10. The apparatus substantially as hereinbefore described with reference to o oo the accompanying diagrams. z o0 oe oo [R:\LIBLL08640.doc:lzg