WO1999038662A1

WO1999038662A1 - Apparatus for removing bark from a flow of timber containing wood and bark

Info

Publication number: WO1999038662A1
Application number: PCT/FI1998/001011
Authority: WO
Inventors: Keijo Alander; Pentti Huhta; Keijo Ventola
Original assignee: Andritz-Patentverwaltungs-Gmbh
Priority date: 1998-01-29
Filing date: 1998-12-22
Publication date: 1999-08-05
Also published as: SE0002710D0; NO314790B1; NO20003870D0; FI103717B1; AU733175B2; ES2197734A1; ES2197734B1; FI980196A0; FI980196A; BR9814914A; NO20003870L; AU1761899A; FI103717B; SE517091C2; SE0002710L

Abstract

The invention relates to an apparatus for removing bark from a wood-and bark-containing flow of timber to be fed into the apparatus. 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 conveyor, crosswise to a moving direction (A) of the flow of timber, for providing the conveyor with a bay (4).

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 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 system. However, the bark balls and some of the long bark strips are difficult to remove by means of a roller system; a moderately close-spaced, timber (pieces of wood) conserving roller system tends to leave almost the entire bark ball and some of the loose barks in the flow of timber, whereas a wide- spaced roller system removes most of the loose barks and even some of the bark balls but results simultaneously major losses of timber.

The Applicant's earlier patent FI 76511 discloses an apparatus as described above for removing barks. Operation of the apparatus is based on a roller system, including studded rollers and smooth-surface rollers, which are 2 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 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.

An object of the invention is to provide an apparatus of the above type, which is capable of removing various barks, especially long barks and bark balls from a flow of timber containing wood and bark and which apparatus is at the same time still capable of preventing timber from unnecessarily discharging along with barks.

According to the invention, this object is achieved in such a manner that and an apparatus of the invention is characterized in that 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 an apparatus of the invention, 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 a preferred embodiment of the invention, the arrangement is such that the bay is constituted by one or more smooth rollers and one or more profiled rollers. In this context, the term smooth roller indicates that the roller has a cross-section which is throughout essentially circular. Respectively, the term 3 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 shows an apparatus of the invention in a schematic plan view.

Fig. 2 shows a section along a line ll-ll in fig. 1.

The apparatus of the invention, shown schematically in the drawing, is designed to remove 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.

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 4 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 inven- tion 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.

The 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 provided with a number of bulges, as depicted in the drawing. 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 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 5.

The shake roller 1 , smooth rollers 2, and profiled rolers 3, 3a, 3b are conventionally journalled at the ends thereof to the frame elements of the apparatus. 5

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 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 rollers 3 lining the bay 4 are as a rule maintained consistent with the moving direction A of a flow of wood. A principal exception to this rule is the roller 3 closest to the shake roller 1 (the left-hand roller 3 in fig. 2), 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 the best possible result in terms of separating the barks. 6

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.

Claims

7 Claims

1. An apparatus for removing barks from a wood- and bark-containing flow of timber to be fed into the apparatus, characterized in that 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 conveyor, crosswise to a moving direction (A) of the flow of timber, for providing the conveyor with a bay (4).

2. An apparatus as set forth in claim 1 , characterized in that the bay (4) is constituted by one or more smooth rollers (2) and by one or more profiled rollers (3).

3. An apparatus as set forth in claim 2, characterized in that the bay (4) is constituted by a number of alternately arranged smooth rollers (2) and profiled rollers (3).

4. An apparatus as set forth in claim 2, characterized in that the smooth rollers (2) and the profiled rollers (3) have a peripheral speed and a rotating direction which are adapted to be selected independently of each other.

5. An apparatus as set forth in claim 3, characterized in that the smooth rollers (2) 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 (2) in an independently adjustable manner.

6. An apparatus as set forth in claim 3, characterized in that the profiled rollers (3) 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 profiled rollers (3) in an independently adjustable manner. 8

7. An apparatus as set forth in claim 2, characterized in that the bay (4) has a length which in the lengthwise direction is less than the average length of tree trunks to be handled.

8. An apparatus as set forth in claim 2, characterized in that the bay (4) has a depth (s) which is at its maximum at the end of the bay adjacent to the shake roller (1 ).

9. An apparatus as set forth in claim 1 , characterized in that the shale roller (1 ) has a rotating speed which is adapted to be independently adjustable.