The present invention relates to a barking method, and a device for utilization of the method.

It is previously known to perform barking of a log while the log is made subject to a linear displacement movement through and past a barking apparatus. As examples of such barking methods can be mentioned barking using barking means such as a chain, wire or similar, which is brought to take up frictional contact against the log to be barked, as for example disclosed in SE 122 987, SE 124273, SE 130000, SE 139367 or SE 145 114, and with necessar contact force being obtained by means of one or a number of spring members. An alternative embodiment, including a triangular link system carrying a barking knife and with springs causing contact pressure, and including a motor driven drive means, is disclosed in CH 233629, as a complete unit intended to perform a rotary movement along a tree, thereby performing a surrounding barking operation by means of the barking knife.

Previously known methods do not facilitate adjustment of the removal capacity during the barking operation, since the contact pressure of the barking member against a log is entirely related to the force applied by the springs used. An ideally suited barking method should allow for such a continous adjustment of the removal capacity, which should be related to the type of log, but also the existing season of the year, since barking can be performed with less contact pressure at higher temperature (summer time) than at a lower temperature (winter time). The spring members are also less suited for location within a barking unit, since small bark fragments can be located between adjacent turns in the springs, and thus completely change a predetermined contact pressure for the spring loaded barking members.

The object of the present invention is to disclose a barking method, and an apparatus for util zation of the method, offering the possibility to continously change the barking depth during operation, without changing the feeding speed of the log, and also removing the problems of changes in contact pressure related to previously known spring loaded barking members. Furthermore, the present invention also makes it possible to

perform barking with a barking unit having an extremely uncomplicated design, having high dependability in operation, low manufacturing costs, and requiring a minimum of maintenance.

The method according to the present invention is based upon that a log during a substantially linear feed movement is brought to pass one or a number of barking means, arranged to perform a surrounding and rotary movement in relation to the log, and it is mainly characterised in that the barking means by influence from centrifugal force during the surrounding and rotary movement in relation to the log are pressed against the log, and that the contact pressure of the barking means is continously variable by an increase/decrease of the rotary speed for the barking means in relation to the iog.

The apparatus for utilization of the method according to the invention includes a rotary member wherethrough a log is arranged to pass during a linear feed movement in the longitudinal direction of the log, said rotary member being arranged to support barking means, arranged to debark a log by means of frictional contact or a cutting operation, and it is mainly characterised in that the barking means are arranged attached or joined with means which under influence of centrifugal force press the barking means with a contact pressure related to the rotary speed of the rotary member.

A number of non-restricting examples of embodiments of an apparatus for utilization of the method according to the present invention are more fully described below with reference to the accompanying drawings, in which:-

Fig. 1 shows a cross-sectional view of a first embodiment of an apparatus for utlization of the method according to the invention;

Fig. 2 shows a view substantially corresponding to Fig. 1, and with the first embodiment slightly modified;

Fig. 3 shows a cross-sectional view of a second embodiment for utilization of the method according to the invention;

Fig. 4 shows a view in longitudinal section of a third embodiment for utilization of the method according to the invention; and

Fig. 5 shows a plan view of a barking means included in the embodiment shown in Fig. 4.

With reference to Fig. 1, a first embodiment according to the present invention is shown, comprising a slingshaped member 1 formed from a chain, wire or similar, attached at two opposed points against two pistonshaped counterweights 2, 2 ^' , axially displacable in a surrounding tubular member 3, 3 ^' . The slingshaped member 1 may advantageously be arranged to carry at least two cutting means 4, 4 ^' , located in an intermediate position in relation to the attachment points for the slingshaped member i against the counterweights 2, 2 ^' . The tubular members 3, 3 ^' are arranged attached against a drumshaped member 5, arranged to perform a rotary movement in relation to a log 6 moved through the slingshaped member 1. It is further shown how the drumshaped member 5 can be arranged with outwardly extending fan wings 7, arranged to cause an air stream in a surrounding housing 8 having an outlet opening 9 for removed bark. The drumshaped member 5 is arranged with peripherally located through openings, through which removed bark can be thrown out, thereafter being transported by the air stream in the housing 8 to the outlet opening 9. Furthermore, two spring means 10, 10 ^' are shown, attached to the sl ngshaped member i at points within an intermediately located region in relation to the attachment points for the slingshaped member 1 to the counterweights 2, 2 ^' , intended to secure that the slingshaped member 1 is opened maximally when the drumshaped member 5 does not rotate, or rotates at a low speed. It should be noted, that such spring means 10, 10 ^" are not always required for applications in which the drumshaped member 5 is maintained rotating with a low rotary speed when a log 6 is inserted into the slingshaped member 1, since the slingshaped member 1 due to its own weight, and the influence from centrifugal force, can take up such a configuration that insertion of the log 6 is facilitated.

When used, a log 6 is inserted into the drumshaped member 5 into a position where a first end portion is surrounded by the slingshaped member 1, whereafter the rotary speed of the drumshaped member 5 is

increased. As a result, the pistonshaped counterweights 2, 2 ^' are made subject to a centrifugal force and perform a displacement movement in relation to the surrounding tubular members 3, 3 ^" in direction away from the rotary centre of the drumshaped member 5, whereby the slingshaped member 1 is stretched, and pressed in di ection against the outer peripheral surface of the log 6. The cutting means 4, 4 ^" are thereby obviously also pressed into contact, while given a rotary movement by means of the drumshaped member 5, and perform surrounding debarking of the log 6. Since the log simultaneously is fed with a linear movement through the drumshaped member 5, debarking is performed over the entire length of the log 6.

Since it is undesirable for certain applications to reduce the rotary speed of the drumshaped member 5 when a log 6 is inserted, as well as stopping the rotary movement of the drumshaped member 5 completely, it is obviously also possible to use forced control to move the counterweights 2, 2 ^" in direction towards the rotary centre of the drumshaped member 5, while same is rotating with a rotary speed adapted for barking. This alternative possibility is basically illustrated in Fig. 2, in which the counterweights 2, 2 ^" are arranged with studshaped members 11, 11 ^" extending in direction away from the drumshaped member 5. It is further shown, how previously discussed spring means 10, 10 ^" , which obviously can be used two accomplish an opening movement for the sling i, can be replaced by two wires 12, 12 ^' or similar, each one attached to a centrally located part of the sl ngshaped member 1, and extending to a point outside the peripheral surface of the drumshaped member 5. By influencing the studshaped members 11, 11 ^" and the wires 12, 12 ^" with forces in the directions indicated by arrows, an opening movement can be performed, despite a high rotary speed being maintained for the drumshaped member 5. As soon as the forces applied are removed, the slingshaped member 1 with associated cutting members 4, 4 ^" return to a contact position pressed against an inserted log 6.

Fig. 3 is only intended to disclose how the number of slingshaped members 1 can be varied as desired, and shows an embodiment corresponding to Fig. 1, but including two sl ngshaped members 1, 1 ^" . It should be noted, that the number of slingshaped members 1, 1 ^" can be increased further, in which case these are located successively

following each other in the drumshaped member 5.

It should also be noted, that previously mentioned cutting members 4, 4 ^' also can be excluded, i.e. necessary debarking can often be performed by

5 means of frictional contact between the slingshaped member 1 and the log 6.

The possibility to use centrifugal force for obtaining required contact pressure for the barking means also make other embodiments possible, and

10 such a further example is shown in Figs. 4 and 5. According to this embodiment, chains, wires or similar are not used to accomplish barking, or to carry cutting members, intended to perform barking. Instead one or preferably a number of barking means are used, comprising a pivotally attached member 13, 13 ^" , adjacent to a first end portion carrying a

15 cutting means 14, 14 ^' , and adjacent to a second end portion carrying a counterweight 15, 15 ^' . Said pivotally arranged members 13, 13 ^' are supported by a rotary member 16, into which a log 6 is insertable, and through which same is moved in a substantially linear feeding movement. By imposing a rotary movement on the rotary member 16, the

20 counterweights 15, 15 ^' are made subject to a centrifugal force, causing the counterweights 15, 15 ^' to move in direction away from the rotary centre of the rotary member 16. As a result, the pivotally attached members 13, 13 ^' perform a pivoting movement, whereby the cutting means 14, 14 ^' carried adjacent to the first end portion are pressed against

25 the peripheral surface of the log 6, and during a rotary movement perform debarking.

By arranging the cutting means 14, 14 ^' inclined in relation to the longitudinal direction of the log, a further advantage is obtained, 30 since the log is made subject to a feeding movement, as schematically illustrated in Fig. 5. This feature may for many applications result in ~\ that a separate feeding device for the linear displacement movement of the log 6 is not required.

35 Possibility to insert a log 6 while maintaining a rotary speed adaped for barking is also offered, e.g. by restricting the pivoting movement of the pivotally attached members 13, 13 ^' in direction towards each other, or by causing a forced opening movement of same, e.g. by a forced

movement of the counterweights 15, 15 ^' in direction towards the rotary centre of the rotary member 16 with a not shown means. Insertion at a reduced rotary speed can obviously also be performed.

The removal capacity can be affected by influencing the linear feed speed of the log 6, and also by changes in the rotary speed of the barking means around the log 6. An increased rotary speed will obviously result in an increased contact pressure, and a reduction of the contact pressure is accomplished by a reduction of the rotary speed.

The present invention thus makes it possible to use centrifugal force to obtain required contact pressure when barking, and also a previously unknown method to vary said contact pressure in a simple way. it is further possible to accomplish fast and continous barking of successively following logs, and simple and reliable technical designs are also offered.

Shown and described examples of embodiments are only intended to serve as examples of embodiments within the scope of the inventive thought and following claims, since many modifications obviously can be made, in order to meet specific requirements. It should also be mentioned with regard to the embodiment indicated with reference to Figs. 4 and 5, that advantageously the pivotally attached members 13, 13 ^' obviously can be arranged with means for contact with the peripheral surface of the log 6, intended to serve as barking depth restricting means, and which thus restrict the depth whereby the cutting means 14, 14 ^' can penetrate into a log 6.