AU620047B2 - Compression log debarking apparatus - Google Patents

Description

ir~ 62 0 0. 417 COMMONWEALTH OF AUSTRALIA PATENTS ACT 1952-1962 COMPLETE SPECIFICATION (Ori gi nal FOR OFFICE USE.

Cl ass Int. Class Application Number: Lodniqd: 41 i r I I *41411 Complete Speciflcation Lodged: Accepted: Published: Priority: Rel ated Art: Name of Applicant: Address of Applicant: Actual Inventor(s): COMMONWEALTH SCIENTIFIC AND RESEARCH ORGANISATION

INDUSTRIAL

Lirestone Aso,,ue, Campbell Austral ip '9 ,'api tal Territory 2601 of Australia ROBIN 14INGATE-HILL and IAN JOSEPH MACARTHUR Address for Service: DAVIES COLLISON, Patent Attorneys, 1 Li ttl e Coll1i ns. Street,. Mel bourne V 3000,..Austral ia Complete Specification for the invention entitled: "1COMPRESSION LOG DEBARKING APIPARATU-S" The following statement is a full description of this invention, REMINT OF RECEIHCl uding the best method of performing it known to us-

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2 -2- Technical Field This invention concerns the removal of bark from logs, and more particularly concerns apparatus for the compression debarking of logs. It is particularly suitable for the removal of bark from eucalypt logs having thick, stringy, fibrous bark which cannot be removed effectively by other debarking mechanisms.

Background to the Invention 10 There are a number of techniques for removing the bark from logs.

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0 Probably the best known debarkers are those which use o rollers carrying teeth on their outer surfaces. The t teeth are designed and positioned to rip pieces of bark from a log pa'sing between the rollers until all the bark is removed. Examples of such debarkers are described in the specifications of US patents Nos o°o 3,363,720 (to G W Brock and H J Merrifield) and 9 a 3,587,685 (to N K Morey and L N Smith).

0 4 20 A similar approach to debarking is found in the drum debarkers. With a drum debarker, logs are passed o through a rotating drum which has internal vanes or ribs. As the logs are tumbled within the drum, they strike each other and the vanes or ribs within the drum, and these impacts act to tear the bark from the logs. Descriptions of drum debarkers are found in the book entitled "Handbook of Pulp and Paper Technology" (second edition), edited by K W Britt and 3 published by Van Nostrand Reinhold Company, at pages 103 and 122, and also in the book entitled "Forest Products, their Sources, Production and Utilization", by Panshin Harrer, Bethel and Baker, published by McGraw-Hill Book Company (second edition, 1962), at pages 332 to 335. Such drum debarkers are unsuitable for debarking stringy-bark eucalypts and other species in Australia, The rotary or ring debarkers a number of models 10 have been used cut the bark with a knife before it 3 is stripped from a log. A typical ring debarker has o 1 a hollow rotor unit within which are mounted inwardly projecting cutters or barking tools. The cutters or *oo barking tools are rotated about a log as it is moved o' 15 through the rotor to cut or st:rip the bark from the log. Examples of developments in rotary debirkers are found in the specifications of Australian patents o°C Nos 479,105 (to Kokum Industri Aktiebolag) and 501,776, (to V L Valo), and Australian patent v 0 applications Nos 21267/83 (Hutson) and 66304/86 o (Fuji Kogyo K K).

A third debarking technique, known as compression c 0debarking, which is suitable for removing bark from stringy-bark eucalypts, involves the application of substantial pressure to the bark of a log, to break the bond between the bark and the wood, and leave a tube of bark surrounding, but separated from, the wood. The tube of bark is then cut into strips by a knife, which is typically mounted on a roller 4 downstream from the pressure-applying rollers, although the cutting of the bark may occur before, during or after the application of pressure to the bark. Examples of this type of debarker are described in the specification of Australian patent application No 82427/87 (now No 604,514) in the name of Commonwealth Scientific and Industrial Research Organisation, and in the specification of the corresponding US patent No 4,875,511.

10 Other debarking techniques include hydraulic barkers using water jets under high pressure, flails (see the a specification of Australian patent No 506,204 to o L J Emmins), "knocking" the bark from a log (see the specification of Australian patent No 511,333 to 15 G A Williames), and, of course, manual removal of the bark with axes and the like.

The present invention concerns the third debarking technique referred to above, compression debarking.

Two recent proposals for an improved approach to compression debarking were the subject of the aforementioned Australian patent application S1No 82427/87, in the name of Commonwealth Scientific t and Industrial Research Organisation. One of those

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t proposals (excluded from the specification by amendment and thus not featured in the specification of application No 604,514) involves the passage of a log through the open-ended passage defined by three rollers which are mounted on a frame with their axes m~UfrL3 of rotation arranged angularly relative to each other and to the elongate direction of the passage. Thus, instead of being parallel to each other, the axes of the rollers are skewed relative to the elongate direction of the passage and the rollers form a tapered or converging passage. The rollers all rotate in the same direction, and at least two of the rollers are mounted resiliently on their support frame, to enable the cross-sectional dimension of the passage to change to allow logs of various size to be ol debarked. The cylindrical outer surface of each o> roller is grooved or is otherwise roughened, or is ,a provided with welded-on bars or the like. The rollers may be rotated at different speeds.

15 A log that is to have its bark removed is fed endwise into the passage and passes through it under the influence of the grip on the log by the outer surfaces of the rollers combined with the rotation of aoa* the rollers. As the log is drawn through the tapered 20 passage, it is subjected to increasing radial compressive forces,, and these forces cause the bark i to separate from the wood of the log. One of the l l rollers is provided with a circumferential "knife" on its outer surface, to cut through the loose bark which tends to remain as a tube around the body of logs of rough, stringy-barked eucalypts and the like.

The second proposal disclosed in the specification of the aforementioned Australian patent application No 82427/87 (and now the sole subject matter of the specification of Australian patent application No 604,51, and US patent No 4,875,511) involves the provision at least two pairs of rollers, each pair mounted with the axes of its rollers parallel to each other, and at an angle to the axial direction of the other pair of rollers. The outer surface of each roller is concave, and the pairs of rollers are mounted in spaced apart relationship along the path followed by a log one pair of rollers thus being 10 effectively downstream of the other pair or pairs. A log to be de-barked is passed between the rollers of the first pair, then through the second pair of rollers, and then between other pairs of rollers if present. The rollers of at least the first pair are 15 grooved or otherwise roughened to provide a firm grip on a log. Fach roller of the final two pairs of rollers is provided with one or more helically-positioned knife blades on its outer surface.

0i When a log to be debarked is fed into the first pair of rollers, the first rollers apply a compressive force to the log to such an extent that the bond I between the bark and the wood is broken and the bark separates from the timber body of the log. The bark S 25 remains as a tube of enlarged cross-section around the timber body. Knife blades affixed to the rollers cut the tubular bark into strips, hich fall from the log. This arrangement is effective with logs having a substantially uniform cross-section with a diameter approximatly equal to twice the radius of curvature -7 7 of the concave shape of the rollers. However, it exhibits problems when the logs are not essentially circular in cross-section and when the logs have large branch stubs and other irregularities, which tend to block the forward movement of the log through the pairs of rollers.

Disclosure of the Present Invention It is an object of the present invention to provide improved forms of compression debarking equipment of the rotatinq log type, in which the log is rotated during the !pplication of pressure to separate the bark from the underlying timber.

*0r0 This objective is achieved by providing log debarking equipment having at least two sets of rollers defining an aperture through which a log is passed, each set of rollers consisting of either three rollers or four rollers.

In the case of sets of three rollers, in each set of rollers, one roller is mounted on a frame so that its 20 location relative to the aperture it helps to define is fixed and the other two rollers are mounted in a bogie-type arrangement. The bogie arrangement is moveable relative to a log positioned in the aperture r to enable the three rollers to apply pressure to the bark of the log. The two bogie-mounted rollers of each set are driven to rotate in the same direction; the single roller may be driven but will usually be free to rotate about its own axis. The single roller 0 .4 cutting blade, although the cutting of the bark may be effected at the beginning, during, or after the passage of the log through the compression debarker.

If there are four rollers in each set of rollers, the four rollers will be mounted in pairs, each pair of rollers being mounted in a bogie-type arrangement.

8 S0in Bth e last set of rollers (which irollers may be seond setable elative to a support frame to enable the four of rollers of then only two sets of rollers to apply pressure used) w ill usually be a rollthe aerture defined by the set o cutting blade, although the cutting of the bark may be effected at the beginning, during, or after the passage of the log through the compression debarker.

If there are four rollers in each set of rollers, the frollers. Normally, however, one bogie-mounted pairs, each pair of Srollers beingll b mounted in a bogie-type arrangement.o the support frame, and only the other pair of 0 ~10 Both bogie-mounted pairs of rollers may be moveable 'elative to a support frame to enable the four 4" 4 20 then applied to the bark of the log by all four rollers of the set of rollers to apply pr essure to awill t be driven. One of the rollers of the set may be provided with means to cut through bark that has been log positioned f in the aper centre of the log by the set of rollers. Normally, however, one bogie-mounted pair 15 of rolapplied pressure although,ed fixedly relatve to the cutting of the bark may be effected separately of the passage of a log through ill be moveable relative to the log, to ensure that the log is held against the .KB. fixed pair of bogie-mounted rollers and pressure is r' 20 then applied to the bark of the log by all four tr,r rollers of the set. Normally all four rollers will be driven. One of the rollers of the set may be t r provided with means to cut through bark that has been loosened from the timber centre of the log by the applied pressure, although, as noted above, the jt-/~b 'cutting of the bark may be effected separately of the passage of a log through the rollers.

'Eli~ j~ il- 9 Thus, according to the present invention, there is provided apparatus for removing the bark from logs by the compression debarking technique, the equipment comprising: a) at least two sets of rollers, each set of rollers being mounted in spaced apart rel: -nship relative to the other set or sets of rollers, each set of rol!.ers defining an aperture through which a log may pass as it traverses the S 10 apparatus; in which each set of rollers comprises: s i) a first roller and a second roller mounted for rotation about respective, spaced apart, o parallel axles supported in a bogie-like 0 0* 15 arrangement by a first support member, said a Ge first support member being moveable relative to a support frame and to a log positioned in said aperture, to enable said first and ~second rollers to apply pressure to the log; 00r 20 and ii) at least one further roller but not more than 0 two further rollers, said or each further 9 roller being mounted for rotation about a 9 respective axle supported by a second support 25 member which is fixed in relation to said 9° support frame, said or each further roller applying pressure to the log as a consequence of the pressure applied to the log by the first and second rollers; 10 b) motor means to drive at least said first and second rollers of each set in the same direction of rotation about their respective axles; c) respective movement means associated with each set of rollers to cause its associated arm to nove the respective first and second rollers towards and away from the log and to apply pressure thereto; and d) cutting means adapted to cut through the bark of the log.

lo: SNormally, as indicated above, the cutting means will .comprise at least one cutting blade on the outer surface of one of the rollers rollers encountered by p the log as it traverses the debarking equipment.

In a preferred form of this arrangement, there are two further rollers, which are mounted in a bogie-like arrangement in a manner similar to that of mi44 t£hs first and second rollers. In this arrangement, ti each bogie-mounted pair of rollers are preferably narrow rollers, offset relative to each other, so that each roller of these pairs of rolers will provide traction on a log of small diameter, relative to the diameter of the rollers, that is being debarked by the equipment of the present invention.

It is also preferred that each support member is controllably rotatable about an axis that is orthogonal to its bogie axle to vary the pitch of the rollers relative to a log passing through the 11 equipment. In this form of the present invention, the rollers each preferably comprise a steel wheel to which polyurethane material is firmly attached, the polyurethane material being shaped to be part of a sphere having a radius which is substantially equal to the radius of the steel wheel.

These and other features of the debarking equipment of the present invention will be more clearly understood from the following description of 10 embodiments of such equipment. These embodiments are provided by way of example only. In the following

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6 description, reference will be made to the a* accompanying drawings.

Goa Brief Description of the Drawings Figure 1 is a schematic diagram illustrating the roller arrangements of the present invention and of the inventions described in the specification of the Saforementioned Australian patent application No 82427/87.

Figure 2 is a partly schematic view, in the direction 4 4 of travel of a log, of a set of three rollers of one form of the equipment which constitutes the first aspect of the present invention, with a thin log passing through the aperture that is established by the set of rollers.

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&44 eo 4 4O4040 4 40 *4 4 4( ,44 it.' 04 44 4i 4 4 4 12 Figure 3 is similar to Figure 2, but with a log of large diameter passing through the aperture that is established by the set of rollers.

Figure 4 is a partly schematic top view of the equipment illustrated in Figures 2 and 3, with a log passing substantially horizontally through the equipment.

Figure 5 illustrates one arrangement of a driven pair of rollers in a bogie-like support member.

10 Figure 6 is a view, in a direction similar to that of Figure 4, of a preferred arrangement of a driven pair of rollers in a bogie-like support member.

Figure 7 is a perspective sketch illustrating an embodiment of the present invention for use with tree 15 :felling equipment.

Figure 8 is a sectional view through a poeferiad form of roller for the embodiment of Figure 7.

Figure 9 illustrates a roller of the type shown in Figure 8, fitted with bark cutting means.

Figure 10 illustrates a schematic mill installation of equipment that is essentially the same as the embodiment illustrated in Figure 7.

-ifurther roller being mounted for rotation about a respective axle supported by a second support member which is fixed in relation to said support frame, said or /2

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13 Detailed Description of the Illustrated Embodiments Figure 1, as indicated above, illustrates the roller configurations used in the present invention and in the embodiments described in the specification of Australian patent application No 82427/87. Each pair of drawings in Figure 1 illustrate an end view of, and a view from above, a log passing through compression debarking equipment and having its bark removed. Specifically, Figures l(b) and l(c) show equipment in which the log is rotated about its long axis as it passes through the compression t* debarking equipment, and Figures l(e) and 1(f) 4 illustrate the roller arrangements of compression «o odebarking equipment in which the log is debarked 444 15 wji .out rotation of the log about its long axis. The S" arrangements of Figures l1a), 1(d) and l(e) are those described in the specification of Australian patent application No 82427/87 before it was amended. The I arrangement of Figure l(b) corresponds to that illustrated in Figures 2, 3 and 4 of the present S specification. The arrangements of Figure l(c) and Figures 5, 6, 7 and 8 correspond. The roller (E rangement of Figure l(f) relates to log debarking equipment that was described in the complete no 25 specification of the present application, filed I. 20 October 1988, which description has now been deleted by amendment of that complete specification.

The set of rollers shown in Figures 2 and 3 typifies a set of rollers for use in a basic mill installation of the present invention. It consists of a first i ss 14 roller 20, a second roller 21 and a third roller The third roller 10 is rotatable about an axle 11 that is supported by a supporting bracket 12. The supporting bracket 12 is rotatably mounted on a swivel member 9 on a rigid frame member 13. Another frame member 14 (which is shown as part of a general framework of the equipment) supports an axle 15 that provides a pivot axis for one end of an arm 16. The other end of the arm 16 carriec a swivel member 8 o 10 upon which a support bracket 17 is rotatably mounted.

A supporting member 19 forms, with the first and 1 sejond rollers 20 and 21, and their associated axles *oo0o 22 23, a bogie-like arrangement that is connected to the support bracket 17. The rollers 20 and 21 are oa 15 mounted on the supporting member 19 with their outer surfaces in close proximity to each other.

A hydraulic ram 7 is used to control the position of oie the support bracket 17 relative to the third roller 10. However, mechanical engineers will appreciate a s o 20 that the hydraulic ram may be replaced by alternative movement means for the arm 16, such as a worm and nut arrangement, or a rack and pinion arrangement. The hydraulic ram 7 (or its mechanical equivalent) of Figure 2 acts not only to ensure that the log 24 is o 25 brought into contact with the rollers 10, 20 and 21, but also to apply, through these rollers, a pressure upon the bark which is sufficient to separate the bark from the wood of the log.

)-0 -4J The following statement is a full description of this invention, REPRINT OF RECEI l uding the best method of performing it known to us Coo000o 2 2O0 0 .I II I .I li I i- I I e i I s44 14 ,04 044404 s s 0 04 *444 *4, 15 With this arrangement, as shown in Figure 2, a log 24 that has a small diameter relative to the diameter of the rollers 10, 20 and 21, when inserted between the set of three rollers, is contacted by all three rollers 10, 20 and 21 when the ram 7 brings the support member 17 towards the roller Figure 3 illustrates how a log 25 having a large diameter relative to the rollers 10, ?0 and 21 can also be transported through this set of rollers 10 without having to change any constructional aspect of the rollers and their mounting arrangements. The dashed outline shows the offset, relative to the log, of the third roller 10A of a second set of rollers The first and second rollers of the second set C-f rollers have not been illustrated in Figures 2 and as to do so would produce a cluttered and possibly confusing drawing.

In the arrangement shown in Figures 2 and 3, if one of the rollers 10, 20 and 21 is rotated, the log 24 or 25 will also be rotated (provided the rotating roller can "grip" the surface of the bark on the log). In practice, both of the rollers 20 and 21, will be mechanically driven, and preferably all three rollers are mechanically driven so that they rotate in the same direction. In addition, all three of the first set of rollers in a debarking equipment based upon the arrangement shown in Figures 2 and 3 will have outer surfaces which are grooved, otherwise roughened, or provided with welded-on bars, spikes or 4464 4 406.

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16 the like, to achieve a suitable degree of grip on the bark of a log passing t1lough the rollers.

Furthermore, as will be seen more clearly from Figure 4, the three rollers wilA, have their axes at an acute angle A relative to the .irection of travel T of a log passing through the eqiiipment. This arrangement ensures th \t when the sets of rollers (that is, in Figure 4, the rollers 30, 31 and 32 which form one set, and the rollers 40, 41 and 42 which form a second set) are driven, they cause the log 26 to be transported through the equipment in addition to rol:ating it about its longitudinal axis.

Figure 4 illustrates schematically a compression (or pressure) debarking equipment, with a first set of rollers 30, 31 and 32 and a second set of rollers 41 and 42 causing a log 26 to be rotated while it is transported through the equipment in the direction of the arrow T. The roller 40, however, has at least one knife or cutting edge 44 formed in, or attached to, its outer surface, to cut the loosened bark of the log 26 as it spirals past the roller The, roller ass ,mblies of Figure 4 are connected by respective arms 36 and 46 to associated axles mounted on the framework of the debarking equipment.

Hydraulic rams or their mechanical equivalents (corresponding to the hydraulic rams 7 of Figures 2 and 8 but not shown in Figure 4) ensure that each set of rollers maintains a significant radial applied pressure on the log 26 as it is being transported i 17 through the debarking equipment. The effect of this pressure by the rollers 30, 31 and 32 is to compress the bark as it passes through the set of rollers.

This causes some expansion of the bark, so that it becomes separated from the timber body of the log.

The bark then remains substantially as a tube around the body of the log until it reaches the rollers 41 and 42. When the log is pressed against the roller 40, the bark is cut into at least one strip by the cutting edge(s) 44 on the outer surface of this *4ol roller.

It is well known that not all, bark behaves in the P P same manner. Using the equipment of the present invention, the "pitch" of the rollers is adjustable to suit the type of bark on the log being debarked.

To change the pitch of the rollers, the angle A (Figure 4) is varied by rotation of the supporting members 33 and 43 (corresponding to the supporting bracket 12 of Figures 2 and 3) and the supporting members 17 about respective swivel axes.

1 An alternative arrangement of a pair of bogie-mounted t rollers is shown in Figure 5. In this arrangement, the central planes of rotation of the narrow rollers and 51 are displaced laterally with regard to each other. This arrangement enables j c i i ~i it i N 18 a) the rollers 50 and 51 to be mounted sc chat their outer surfaces follow different paths over the bark surface to achieve more complete compression of the whole bark area and hence more complete bark separation, and b) a drive train arrangement 52 to be included between the central planes of rotation of the rollers.

The use of narrow rollers instead of the more conventionai wide rollers is preferred because Snarrow rollers enable irregularities in the log to be handled more easily. To change the pitch of the roller assemblies, electric motors or stepped hydraulic motors may be used.

Figure 6 shows a preferred form of the bogie-mounted rollers of the equipment illustrated in Figure 4. In this arrangement, a pair of narrow rollers 50 and 51, with their associated driving motors 53 and 54 are mounted on a support member 55. The support member t 20 55 is connected via swivel axle 59 to a generally U-shaped support bracket 57 having side arms 57A.

The support bracket 57 is supported by pivot pins 58 on a pair of arm members 56 which re, in turn, supported on an axle 15 mounted on the frame of the debarking equipment. The operation of the embodiment of Figure 6 will be evident from the above description. Note, however, the preferred r 2Q55 s coneced ia sive axl 59to genraly

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1 19 arrangement of the offset rollers 50 and 51, with the sides thereof adjacent to their respective driving motors aligned with the line B-B of Figure 6.

Figure 7 illustrates a prototype of the present invention that has been constructed to demonstrate how the present invention may be used in association with tree felling equipment, to permit felled trees to be debarked at the point of felling in a forest (thus enabling more logs to be transported from the S2 10 forest in a single load of a timber forwarder). In the Figure 7 embodiment, the fixed single rollers oto and 40 shown in Figures 2, 3 and 4 are each replaced with a second pair of rollers 70 and 71, mounted in a bogie-like arrangement on a support member 75. The support member 75 is connected by a swivel axle 79 to a generally U-shaped support bracket 77 having a pair of side arms 77A (defining t,4 the upright arms of the The side arms 77A are pivotally mounted on pivot pins 78 that are mounted on respective frame arms 76 that are rigidly affixed to a base frame 100. In a similar manner, the rollers 50 and 53 of the Figure 4 embodiment have their equivalent in the rollers 80 and 81. mounted in a bogie-like arrangement on a support member 85. The mounting of the support member 85 in the equipment is similar to the mounting of the support member except that the fixed frame arms 76 are Veplaced with arms 86 which are mounted in known manner, as illustrated, for movement along supporting i.i i; 1-i

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20 cross-members 101 of the base frame 100. The rollers 71, 80 and 81 are each driven by a respective motor 73.

The changing of the pitch of the rollers 70, 71, and 81 is effected by respective hydraulically controlled linear actuators 90, mounted on the support brackets 77 and extending to the associated Ssupport member 75 or 85. However, other forms of k linear actuator, or equivalent mechanical or electro-mechanical linkage arrangements, may be used in place of the hydraulically controlled linear actuators 90. Linear actuators are well known in this art. A convenient recently published reference which describes a range of known mechanical linkages (including linear actuators) is the book entitled Pneumatic Control for Industrial Automation, by Peter and Gordon Smith, published by John Wiley Sons in 1987.

Hydraulically controlled linear actuators are also used in the prototype equipment illustrated in Figure 7 to control the to and feo movement of the arms 86 on the cross-members i01, and the tilting, through 900, of the base frame 100 relative to the bed member on which it was mounted. Again, alternative linkage arrangements (mechanical or electro-mechanical) may be used instead of hydraulically controlled linear actuators, if desired.

i i. i i L j iL -21- When using the equipment shown in Figure 7, it was found that if steel rollers are used, when the pitch of the rollers is varied, the sharp edges of the rollers can dig into the central timber of the log and mark it. This also means that the pressure is being applied to the bark over a small area, and in some instances this has resulted in incomplete separation of the bark from the log. Thus a modified o roller has been developed for use in this type of equipment. The modified roller is illustrated in S Figure 8.

6 aolo The roller of Figure 8 comprises a face plate 105 on which is mounted an annular thick disc 106 of polyurethane material. The disc 106 may be bonded to the face plate 105 or it may (as shown in Figure 8) be held in rigid contact with the face plate by a t aa plurality of bolts 107. This illustrated mounting DCO arrangement permits ready exchange of the disc 1.06 when it is worn or needs (for any other reason) to be O O.I 20 replaced. The face plate is mounted in P Sconventional manner for rotation by a motor. The disc 106 is preferably machined so that its outer surface is part of a sphere, having a radius substantially the same as the radius of the face plate. With this form of disc 106, as the pitch of the rollers is varied, bark on the log is always substantially tangential to the roller surface.

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22 22 it has also been found, from using the prototype equipment illustrated in Figure 7, that all of the rollers should have the same diameter, each of the rollers should be driven by a respective associated motor, and all of the pitch angles of the rollers should be the same, otherwise a build up of bark can occur and jam the equipment. In the prototype equipment, a suitable motor speed was found to be one r* which rotated the rollers at a rate of 60 revolutions per minute.

STo include a cutting mechanism for the bark of the log, the rollers illustrated in Figure 8 can be o modified to the form shown in Figure 9. The roller of Figure 9 has a steel cutting disc 108 mounted on the polyurethane thick disc 106. It has been found that it is preferable to have a roller of the Figure 9 type as one of the lead-in rollers, to cut the bark before it is compressed. This arrangement gives a better effect than cutting the loosened tube of bark 20 after it has been separated from the central timber :of a log by the pressure applied by the rollers.

The equipment illustrated in Figure 7, fitted with 4 rollers of the type illustrated in Figures 8 and 9, has been found to be particularly effective for the removal of bark from logs having tight bark or stringy bark, which are difficult to debark by other techniques.

23 When the embodiment of Figure 7 is incorporated into tree felling equipment, it will be mounted on a bed member attached to a prime mover, with the base frame 100 inclinable through at least 900 relative to the prime mover. To fell and debark a tree, the prime mover is moved towards the tree with the plane of the base frame substantially vertical and the arms 76 and 86 widely separateu. The arms 86 should be fully retracted until each of the rollers 70 and 71 contact the tree trunk. The arms 86 will then be moved so that the rollers 80 and 81 also contact the tree trunk, after which the continued application of hydraulic pressure by the ram which controls the 1* 0 :movement of the arms 86 causes each set of four rollers to clamp the trunk between them.

When the selected tree has been gripped by the two sets of rollers, the tree is cut using (for example) lot, a chain saw mechanism mounted below the "jaws" of the debarking equipment. After the tree has been cut, the entire felling assembly (including the debarking equipment) will be raised and the motors powering the debarking equipment will be activated. This will result in the tree trunk being moved through the debarking equipment. Initially, the severed trunk of the tree will be held by the rollers and rotated by them with the rollers having zero pitch (that is, the angle A of Figure 4 will be 900). This rotation will detach the bark under the rollers and also most (sometimes all) of the bark below the bottom set of rollers and above the out end of the trunk. The .j 1 4 409 prpa 4 06 0 9 04,4,04 0 40 4, 010 I 004, QP4 4 4,44,4 4, 4,g~ 4, 9 p4,pg 4, i, i 24 pitch angle of the rollers will then be changed so that the tree trunk moves vertically downwards under the action of the debarking rollers.

In the case of tall trees, after downward movement of the trunk for about three metres, the chain saw mechanism below the jaws of the debarking equipment will be activated to remove the debarked length of trunk. Some tilting of the felling assembly may be necessary as the trunk is moved downwards, to prevent 10 it striking the ground or other obstacles.

The downward movement of the tree trunk (now less heavy as the lowest portion has been removed) and its debarking are continued, and three metres lengths (or thereabouts) of the trunk are progressively removed.

As this process proceeds, the mass of tree being carried ry the rollers decreases, and the speed of rotation of the remaining trunk and the pitch angle of the rollers may be increased.

A feature of this type of tree felling assembly is that delimbing equipment is normally provided to remove branches from the felled tree. The delimbing equipment may comprise a short chain saw or circular saw, mounted above the debarking equipment with the plane of the bar of the short chain saw, or the circular blade, parallel to the direction cf movement T of the log (trunk) as in Figure 4. The short chain saw or circular saw can then be used to cut branches close to the trunk as the trunk of the felled tree is h. i 25 moved past the short chain saw or the circular saw.

With this feature added, even pine trees with many branches can be delimbed as they are felled and debarked, prior to being loaded on to a timber jinker or trailer for transportation.

Another use of the present invention is in a mill in which logs are debarked. In such a mill i, nstallation, a modified form of the arrangement .A shown in Figures 2 to 6 may be used with the "bogies" os 10 fixed in a lower position so that logs can be fed on to the double rollers of the "bogies" of the first set of rollers. The single rollers of each set of n rollers can then be swung on respective arms to contact the bark of the log as it passes through the debarking equipment.

oar* An example of the use, in a mill installation, of an arrangement having features which are similar to those of the unit shown in Figure 7, is illustrated K in Figure 10. In the Figure 10 arrangement, each set of rollers comprises two pairs of rollers 60 and 61.

The pairs of rollers 60 and 61 are each mounted in a bogie-like arrangement, for rotation about respective axles 62 and 63, journalled in respective support members 64. Each support member 64 is pivotally mounted on a respective support bracket 65 which is rotatably mounted at or near one end of an associated arm 67. Each arm 67 is connected at its other end, through a swivel pin 68, to a framework 100.

Hydraulic rams 69 control the movement of the arms 67 t i 26 relative to the frame 100, and the application of pressure, via the rollers 60 and 61, to the bark of the log 66.

An advantage of a pressure debarking mill installation of the type shown in Figure 10 is that bark stripped from the log 66 will fall clear of the rollers 60 and 61, thus minimising the likelihood of bark jamming the debarking installation.

a SIn both the tree felling and the mill applications of 10 the present invention, provision has to be made to ensure that the rollers have sufficient resilience of O grip upon the log, as pressure is applied, to prevent the debarker being jammed when the surface topography of a log changes suddenly. Sudden variations in diameter occur as a result of swellings (usually asymmetrical) in the log and the presence of the wo stubs of branches. In addition, the roller assemblies should maintain pressure oi the log as its diameter reduces (which happens due to the natural taper of the trunks of trees). When a hydraulic ram is used to move the roller assemblies and apply pressure to a log, the conventional approach of including an accumulator in the hydraulic circuit will ensure that the rcglars adjust to take up the taper in a log and permit the passage of sudden discontinuities in the outer surface of the log.

Known pressure-limiting mechanisms can be used with

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2 7 rack auid pinion and with worm and nut mo-,-ment and preqture applying mechanisms, if such. mechanisms are ussd instead of hydraulic rams.

In case jams in the debarking equipment do occur, or to enable a second compression to be applied over a surfa e region of a lcq if all the bark is not separated from the wood underneath it, the motors driving the rollers are reversible. Reversing the Dt direction of rotetion of the rollers without changing the pitch setting of the rollers will result in the direction of movement of log through the debarkirg 4 equipment being reversed.

44 4 4 cThose skilled in this art will appreciate that although several embodiments of the present invention have been described above, variations to such O d tembodiments may be made without departing from the present inventive concept.

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Claims (11)

1. 2. Apparatus as defined in claim 1, in which the cutting means comprises at least one cutting blade on the outer surface of a roller of the final set of rollers of the apparatus. D00 00oo
2. 3. Apparatus as defined in claim 1 or claim 2, in which each said movement means comprises a Shydraulic ram connected between its associated o J arm and said framework. 0
3. 4. Apparatus as defined in any preceding claim, in which said motor means is able to reverse the direction of rotation of the rollers. Apparatus as defined in any preceding claim, in which there are two sets of rollers. 0- i :I 4 30
4. 6. Apparatus as defined in claim 5, in which there are two further rollers in each set of rollers.
5. 7. Apparatus as defined in claim 6, in which the pairs of rollers, namely the first and second rollers of each set of rollers and the two further rollers of each set, are each mounted in a respective bogie-like arrangement with an associated support member, each support member being connected by a swivel axle to an associated 0 support bracket having a pair of side arms, each o: of said support brackets being pivotally mounted O Aa on a pair of frame arms by pivot pins passing 0000 o 0 through said side arms. 0 p
6. 8. Apparatus as defined in claim 6 or claim 7, in which said apparatus includes a base frame, the frame arms on which each pair of said further oe rollers are mounted being fixedly connected to r a osaid base frame, and the frame arms on which each pair of said first and second rollers are mounted O O being moveable by said movement means towards and SB away from said fixedly mounted frame arms along oo° respective pairs of cross-members of said base *o frame. ooo
7. 9. Apparatus as defined in claim 8, in which said base frame is mounted on a bed member which forms part of a tree felling apparatus, said tree felling apparatus including saw means for cutting M N 31 through a tree trunk and delimbing equipment, said base frame being inclinable relative to said bed member through an angle of at least 900 Apparatus as defined in any one of claims 1 to 4, in a mill installation, in which there are two further rollers in each set of rollers and the first and second rollers of each set of rollers and the two further rollers of each set of Srollers are mounted in respective bogie-like arrangements with associated support members at or near the lower ends of substantially vert cal frame arms, each of said frame arms b: ing pivotally connected at or near its upper end to a main frame, a respective hydraulic ram being connected between each frame arm and said main frame to move said frame arms to enable said bogie-mounted rollers to be moved relative to a a e log passing through said apparatus and to grip nand apply pressure to the bark of such a log.
8. 11. Apparatus as defined in any preceding claim, in which each roller is driven by a respective, reversible motor.
9. 12. Apparatus as defined in any preceding claim, including means to vary the pitch of each roller relative to the longitudinal axis of a log passing through the apparatus. N 32
10. 13. Tree felling equipment incorporating apparatus for the pressure debarking of logs, as defined in any one of the preceding claims.
11. 14. Apparatus for the pressure debarking of logs, substantially as hereinbefore described with reference to Figures l(b) and Figures 2 to 6 and Figure 10 of the accompanying drawings. DATED this ninth day of November 1990 COMMONWEALTH SCIENTIFIC AND INDUSTRIAL RESEARCH ORGANISATION by its Patent Attorneys DAVIES COLLISON 0 0 0 0* 206 0 00 I 01 0 Otto1 0 ~-iOlh~ iC h" ~Cjb~r