AU2005203897B2

AU2005203897B2 - Method for enhancing operation of a debarking roller assembly, as well as pick-up roll to be included in a debarking roller assembly

Info

Publication number: AU2005203897B2
Application number: AU2005203897A
Authority: AU
Inventors: Pentti Huhta; Keijo Ventola
Original assignee: Andritz Oy
Current assignee: Andritz Oy
Priority date: 2004-01-07
Filing date: 2005-01-04
Publication date: 2008-03-06
Anticipated expiration: 2025-01-04
Also published as: ZA200605508B; FI20045002A0; AR048142A1; FI122577B; PT2005065903W; CN100398279C; BRPI0506711A; AU2005203897A1; BRPI0506711B1; SE0501966L; SE529958C2; CN1910023A; FI20045002A; ES2298086B2; MY146306A; WO2005065903A1; ES2298086A1

Description

O METHOD FOR ENHANCING OPERATION OF A DEBARKING SROLLER ASSEMBLY, AS WELL AS PICK-UP ROLL TO BE

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SINCLUDED IN A DEBARKING ROLLER ASSEMBLY t-- Field of the Invention The invention relates to a method as described herein for enhancing operation of a debarking roller assembly. The invention relates additionally to a pick-up roll as 00 oO Cc described herein to be included in a debarking roller assembly for enhancing operation of Ci the roller assembly.

SBackground of the Invention lo In terms of pulp quality, it is important that the amount of barks ending up in chipping along with trees be kept as small as possible. Stripping of bark off the surface of trees is generally performed in a barking drum, in which the relative movement and attrition of trees against each other result in bark stripping off the surface of trees. The loose finely crushed bark falls mostly through the drum's bark holes onto a bark conveyor disposed underneath the drum. However, the loose bark removed in long strips or large sheets tends to emerge with trees out of the discharge end of a barking drum. Such hardto-bark trees include several hardwood species, such as eucalyptus, acacia, hickory, and birch.

If bark is coming out of the discharge end of a barking drum entangled amongst trees as single strips or bark balls (bark balls refer in this context to a heap consisting of more or less intertwined barks and possibly containing also pieces of wood, slivers or the like), most of such bark should be removed prior to chipping or other such operation.

Partial debarking can be performed by means of a special purpose-built roller assembly.

However, bark balls and some of the long strips of bark are difficult to remove with the roller assembly: a close-spaced, wood (pieces of timber) saving roller assembly tends to leave almost the entire bark ball and some of the loose barks within a flow of timber, a large-spaced roller assembly in turn removes most of the loose barks and even some of the bark balls, yet at the same time causes major losses of timber.

The Applicant's earlier Finnish patent application 103717 discloses an apparatus suitable for removing various barks, especially long barks and bark balls, from a woodand bark-containing flow of timber, said apparatus being at the same time capable of preventing unnecessary removal of wood material along with barks. The discussed apparatus comprises at least one shaking roller as part of a timber-flow carrying 1057915-1hxa O conveyor, and a number of rotatable rollers disposed downstream thereof, below a plane of movement defined by said conveyor, transversely to the travelling direction of the flow

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Sof timber, for providing a recessed section in the conveyor. The shaking roller applies a vibration action to the timber, the barks and bark balls entangled within the timber falling either directly between the rollers and thence further onto a lower-level conveyor or the like or ending up in the recessed section included in the inventive apparatus and thence \through between the rollers as a result of the relative movement thereof onto a bark 00oO Mc, conveyor or the like.

N, Such as shaking roller, delivering vertical impacts from below to trees presently io in the process, has proved efficient in most cases intended for dropping the barks from top of the trees onto a roller assembly and further therethrough onto a bark conveyor.

However, in the process of handling the most difficult barks, specifically very tough, strong and long barks, it is not possible to remove all barks by means of such a roller assembly as some of the barks are at least partially entangled around the trees and wedged between the trees or between the trees and the roller assembly, the roller assembly not being able to pull such barks through itself onto a bark conveyor below.

There is a need to provide a method and apparatus, whereby the operation of a debarking roller assembly can be enhanced by enabling barks to be removed to fall more surely than before onto the roller assembly and to travel at least momentarily without constraint upon the roller assembly with no trees impeding their motion, whereby a variety of elements included in the roller assembly are able to pull and drop the barks on a bark conveyor below.

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

Summary of the Invention There is disclosed herein a method for enhancing operation of a debarking roller assembly, said roller assembly being adapted to remove barks from a flow of timber proceeding therealong transversely to the roller assembly's rollers and containing trees and bark stripped off the trees and having the barks at least partially entangled around the trees and wedged between trees or between trees and the roller assembly, wherein at least in one spot of the debarking roller assembly, the trees are subjected to a combined lifting 1057915-1:hxa o motion, lateral movement, and rolling action effected around the longitudinal axis of a tree, for disengaging the trees, presently in said at least one spot, at least momentarily and Sat least partially away from the debarking roller assembly and from other trees presently at the roller assembly, once crossing a pick-up roll, a tree is adapted to be lifted by the action of a lifting blade to the height of 100-500mm above the conveying level, and the lifting height of a tree crossing the pick-up roll is adapted to be established by means of a forced motion produced by the increasing height section.

00oO Mc, There is further disclosed herein a pick-up roll to be included in a debarking I roller assembly for enhancing operation of the roller assembly, said roller assembly being lo adapted to remove barks from a flow of timber progressing therealong transversely to the I roller assembly's rollers and containing trees and bark stripped off the trees and having the barks at least partially entangled around the trees and wedged between trees or between trees and the roller assembly, wherein the pick-up roll comprises a rotatable core member, having its jacket surface provided with at least one lifting blade whose top surface is configured as a helical line and provided with an increasing height section and a decreasing height section, the increasing height section is adapted to commence from the debarking roller assembly's conveying level or from therebelow and the decreasing height section is adapted to extend to the debarking roller assembly's conveying level or therebelow, the lifting blade is adapted to direct a combined lifting motion, lateral movement, and rolling action effected around the longitudinal axis of a tree to a tree, that is crossing the pick-up roll, for disengaging the tree at least momentarily and at least partially away from the debarking roller assembly and from other trees presently at the roller assembly, and there has been arranged one or more pick-up rolls to the debarking roller assembly.

The lifting motion included in the method refers to an action of lifting a tree in such a way that, at a pick-up point, the tree shall momentarily reach the height of 100- 500mm above the conveying level. Thus, the method differs essentially from prior art shaking or vibration, in which a tree is raised in practice by no more than a few 1057915-1:hxa WO 2005/065903 PCT/FI2005/050002 3 centimeters. By virtue of this lifting motion, and a lateral movement integrated therewith and a rolling action effected around the longitudinal axis of a tree, barks fall more effectively than before from top of the trees onto a roller assembly or, in any case, are momentarily released for enabling a roller assembly to pull the barks through the roller assembly onto a conveyor below.

A combined lifting motion, lateral movement and rolling action in a method of the invention is preferably effected by a pick-up roll of the invention. The lifting motion is performed by means of the increasing height section of a lifting blade, which simultaneously rolls the tree around. The lateral movement is effected by means of a helical line produced by the top surface of the lifting blade's increasing height section as the pick-up roll rotates.

In a preferred embodiment of the invention, the lifting motion is implemented not only by means of a forced motion produced by the increasing height section of a lifting blade but also by means of an ejection motion produced by the rotation of a lifting blade. The lifting blade is made adjustable in terms of its rotation speed for readily controlling the ejection motion in terms of its force. Consequently, the presently treated timber and barks are momentarily as disengaged as possible from -each other, the debarking roller assembly being capable of delivering the barks as easily and efficiently as possible onto a conveyor set below the roller assembly.

The rolling action occurring around the longitudinal axis of a tree is most effectively produced in such a way that the increasing height section of a lifting blade's top surface is configured at least for the most part as an Archimedean spiral. The rolling action contributes effectively to the falling of barks from top of the trees.

The lifting blades located in the mid-section of a pick-up roll have the handedness of their helical lines selected preferably in view of having the lifting blades convey trees from the pick-up roll's mid-section towards the pick-up roll's ends.

Respectively, the lifting blades located at the ends of a pick-up roll have the handedness of their helical lines selected preferably in view of having the lifting blades convey trees from the pick-up roll's ends towards the pick-up roll's midsection. By virtue of such configurations, the relative distance between adjacent r- O trees can be momentarily increased for allowing the barks to readily fall onto a roller N, assembly.

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SThe distance between two successive pick-up rolls is preferably greater than the

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average length of presently handled trees. This reduces stresses applied to the pick-up rolls, as it therefore unlikely that timber should ever fall with its entire weight against a single pick-up roll but, instead, the weight-inflicted load shall be distributed at least between the pick-up roll and a given roller in the roller assembly.

00 oO Mc, The debarking roller assembly is preferably provided with a return motion. By N, virtue of this, trees can be worked on the roller assembly back and forth for removing io even the most troublesome barks.

The debarking roller assembly has its width selected preferably in view of providing enough space for currently handled trees to advance essentially in a single tier.

This facilitates measures to provide openings between trees for barks to fall therethrough onto a roller assembly.

Brief Description of the Drawings A preferred form of the present invention will now be described, by way of example only, with reference to the accompanying drawings, wherein: Figure 1 shows a pick-up roll of an embodiment of the invention; Figure 2 shows schematically in a plan view a debarking roller assembly provided with pick-up rolls of an embodiment of the invention; and Figure 3 shows a section along a line III-III in Figure 2.

Detailed Description of the Preferred Embodiment Figures 2 and 3 show a debarking roller assembly designated generally by reference numeral 1, and Figure 1 shows a pick-up roll designated by reference numeral 6 for enhancing operation of such a debarking roller assembly 1. What is explicitly essential in terms of the invention is that a per se known type of debarking roller assembly has been provided with one or more pick-up rolls shown in Figure 1.

1057915-1:hxa WO 2005/065903 PCT/FI2005/050002 The debarking roller assembly i is intended for removing barks 2 from a flow of timber proceeding therealong in the direction of an arrow A transversely to the roller assembly's rollers 3 and containing trees 5 and bark 2 stripped off the trees.

Said flow of timber proceeds carried by the rollers 3 in a channel whose floor is constituted by said rollers. Each roller 3 is bearing-mounted for rotation around a rotation axis 4 and provided with drive means (not shown). The rollers 3 have a relative distance in the roller assembly's advancing direction (direction of the arrow A) selected in view of allowing the barks 2 to fall through between the rollers. The roller assembly may include various types of rollers (not shown) for encouraging the barks 2 to wind up between the rollers and, thus, the barks to fall onto a conveyor below (not shown).

The presently discussed debarking roller assembly 1, which thus includes at least one pick-up roll 6, is intended particularly for the handling of difficult barks 2. These include, for example, barks of some eucalyptus trees coming off in long strips. A problem here is that the barks 2 are at least partially entangled around the trees and wedged between trees or between trees and the roller assembly. In this case, a conventional debarking roller assembly is not always capable of directing and pulling barks through between the roller assembly's rollers onto a conveyor below.

In order to eliminate these problems, the trees 5 are subjected at least in one spot of the debarking roller assembly 1 to a combined lifting motion, lateral movement, and a rolling action effected around the longitudinal axis of trees 5 for disengaging the trees, presently in said at least one spot, at least temporarily and at least partially away from the debarking roller assembly i1 and other trees 5 presently at the roller assembly.

In practice, this is implemented by means of a pick-up roll 6 included in the debarking roller assembly 1.

The pick-up roll 6 is provided with its own drive means for rotating the pick-up roll in the direction of an arrow C. In other words, the pick-up roll 6 can be controlled in operation regardless of the rollers' 3 rotation speed. The pick-up roll 6 comprises a rotatable core member 7, having its jacket surface provided with at least one lifting WO 2005/065903 PCT/FI2005/050002 6 blade 8. The lifting blade 8 has its top surface 9 configured as a helical line and provided with an increasing height section 10 and a decreasing height section 11 (fig. The increasing height section 10 is adapted to commence from the debarking roller assembly's 1 conveying level 12 or from therebelow and the decreasing height section 11 is adapted to extend to the debarking roller assembly's conveying level or therebelow.

The pick-up roll 6 is fitted in the debarking roller assembly 1 as a sort of replacement for one of the rollers 3. Thus, the core member 7 has its highest point not higher than coplanar with the conveying level 12 established by the rollers 3.

Once in line with the pick-up roll 6, a tree 5 is adapted to be lifted by the action of the lifting blade 8 to the height of 100-500 mm above the conveying level 12. This can be effected by means of a forced motion produced by the increasing height section 10 of the lifting blade 8. In terms of operation of the debarking roller assembly 1, however, it is more preferred to implement this by means of a combination of forced motion produced by the increasing height section 10 of the lifting blade 8 the and ejection motioniproduced by rotation of the lifting blade 8.

In order to provide a suitable ejection motion, the pick-up roll 6 is adapted to be adjustable regarding its rotation speed.

The increasing height section 10 of the lifting blade's 8 top surface 9 Is configured at least for the most part as an Archimedean spiral for providing a tree effectively with a concurrent rolling and ejection action. The Archimedean spiral is a curve produced by a spot moving at a consistent speed along a radius rotating at a constant speed.

The lifting blades 8 present in the mid-section of the pick-up roll 6 have the helical lines thereof selected for such a handedness that, as the pick-up roll 6 is rotating, trees 5 become conveyed by the lifting blades 8 from the pick-up roll's 6 midsection towards its ends. On the other hand, the lifting blades 8 present at the ends of the pick-up roll 6 have the helical lines thereof selected for such a handedness WO 2005/065903 PCT/FI2005/050002 7 that, as the pick-up roll 6 is rotating, trees 5 become conveyed by the lifting blades 8 from the pick-up roll's 6 ends towards the pick-up roll's mid-section.

In order to limit a stress applied to the pick-up rolls 6, the distance between two successive pick-up rolls 6 is greater than the average length of presently handled trees The debarking roller assembly 1 is provided with a return motion, in other words the rollers 3 can be rotated both in the direction of an arrow D for an actual feeding motion and in the reversed direction, the roller assembly being capable of working the trees back and forth until the removal of barks is complete.

The debarking roller assembly 1 has its width B selected such that presently handled trees 5 have enough space to advance in a single tier.

Claims

2. A pick-up roll to be included in a debarking roller assembly for enhancing operation of the roller assembly, said roller assembly being adapted to remove barks from a flow of timber progressing therealong transversely to the roller assembly's rollers and containing trees and bark stripped off the trees and having the barks at least partially entangled around the trees and wedged between trees or between trees and the roller assembly, wherein the pick-up roll comprises a rotatable core member, having its jacket surface provided with at least one lifting blade whose top surface is configured as a helical line and provided with an increasing height section and a decreasing height section, the increasing height section is adapted to commence from the debarking roller assembly's conveying level or from therebelow and the decreasing height section is adapted to extend to the debarking roller assembly's conveying level or therebelow, the lifting blade is adapted to direct a combined lifting motion, lateral movement, and rolling action effected around the longitudinal axis of a tree to a tree, that is crossing the pick-up roll, for disengaging the tree at least momentarily and at least partially away from the debarking roller assembly and from other trees presently at the roller assembly, and there has been arranged one or more pick-up rolls to the debarking roller assembly.
3. A roll as set forth in claim 2, whereby once crossing the pick-up roll, a tree is adapted to be lifted by the action of the lifting blade to the height of 100-500mm above the conveying level.
1057915-1:hxa 4. A roll as set forth in claim 2, wherein the lifting height of a tree crossing N' the pick-up roll is adapted to be established by means of a forced motion produced by the O Sincreasing height section. A roll as set forth in claim 2, wherein the lifting height of a tree crossing s the pick-up roll is adapted to be established by means of a forced motion produced by the increasing height section and an ejection motion produced by rotation of the lifting blade. 6. A roll as set forth in claim 2, wherein the pick-up roll's rotation speed is 00 Mc, adapted to be adjustable. N 7. A roll as set forth in claim 2, wherein the increasing height section of lo the lifting blade's top surface is configured at least for the most part as an Archimedean Ni spiral. 8. A roll as set forth in claim 2, wherein the lifting blades present in the mid-section of the pick-up roll have the helical lines thereof selected for such a handedness that trees become conveyed by the lifting blades from the pick-up roll's mid- section towards its ends. 9. A roll as set forth in claim 2, wherein the lifting blades present at the ends of the pick-up roll have the helical lines thereof selected for such a handedness that trees become conveyed by the lifting blades from the pick-up roll's ends towards the pick-up roll's mid-section. 10. A roll as set forth in claim 2, wherein the distance between two successive pick-up rolls is greater than the average length of presently handled trees. 11. A roll as set forth in claim 2, wherein the debarking roller assembly is provided with a return motion. 12. A roll as set forth in claim 2, wherein the debarking roller assembly has its width selected such that presently handled trees have enough space to advance in a single tier. 13. A pick-up roll, substantially as herein described with reference to Figures 1 to 3. Dated 13 December, 2007 Andritz Oy Patent Attorneys for the Applicant/Nominated Person SPRUSON FERGUSON 1057915I.lhxa