A feed roller

Abstract: A feed roller intended for a timber processing unit includes a roller body 10 having disposed on its outer periphery elastically supported engagement devices for driving engagement with a tree trunk 70 advanced by the roller. In accordance with the invention, it is proposed that the engagement devices include mutually separated elements (20) and that each of the elements is moveably connected to the roller body (10) at its outer periphery.

Description: The present invention relates to a feed roller for use in timber processing units, comprising a roller having disposed around its outer periphery body elastically supported engagement devices for driving engagement with a tree trunk advanced by the roller, the engagement devices including separate elements each of which is connected to the roller body. A feed roller of this type is known from WO-A-8901854. Known feed rollers of this kind consist, in principle, of a rubber wheel provided with engagement means or slip protectors in the form of chain links. Although such a feed roller acts gently on the log and, to some extent, is able to adapt to irregularities in the log surface, the rubber ring on the roller becomes worn relatively quickly as a result of rubbing against the log and the chain links. Another drawback is that the chain links are not always able to maintain satisfactory driving engagement with the tree trunk, particularly in the period of sap flow during which the bark has low adherence to the trunk and is easily removed therefrom. The feed roller disclosed in the above mentioned document WO-A-8901854 comprises pin-shaped engagement devices received in the elastic material forming the peripheral surface layer of the feed roller. While in this feed roller the engagement devices are not in rubbing engagement with the roller surface, this roller surface will be exposed to wear from tree trunks in the surface areas between engagement devices. An object of the present invention is to provide an improved feed roller of the aforesaid kind. This object is achieved with a feed roller having the characteristic features set forth in the following claims. Because the engagement devices include separate elements which are each moveably connected to the roller body at the outer periphery thereof, the engagement devices, as distinct from chain links, are prevented from performing sliding and wearing movements against the elastic support, such that said support will be subjected generally to solely pressure and shear forces. The presence of such individually elastically mounted elements also enables engagement with the periphery of the tree trunk to be better controlled. An exemplifying embodiment of the invention will now be described in greater detail with reference to the accompanying drawings, in which Figure 1 is a side view of part of a feed roller constructed in accordanced with the invention; Figure 2 is a sectional view, in larger scale, of a feed roller underload, said section being taken on the line 2-2 in Figure 1; Figure 3 is a part section view of a feed roller, taken approximately along the line 3-3 in Figure 2; and Figure 4 is a perspective view of a drive element, a spring element and part of an inventive roller body, said elements and said part being shown separated from one another. The feed roller shown by way of example in the drawings is intended for use in a crane-carried single-grip type harvesting unit. It will be understood, however, that the invention is not restricted thereto, but can also be applied with other types of feed rollers, for example the feed rollers of sawmills. The illustrated feed roller includes a roller body 10 which has mounted on the periphery thereof a plurality of drive elements 20 between which are disposed, in turn, a plurality of spring elements 40. The feed roller also includes a hub disc or plate 50 and a pair of side plates 60. The roller body 10 and the drive elements 20 are preferably manufactured from extruded aluminium, whereas the hub plate 50 may be manufactured from laser-cut or punched aluminium plate and the side plates 60 from steel plate. As will best be seen from Figures 3 and 4, the drive elements 20 are intended to be connected to the roller body 10 with the aid of groove joints which have the form of mutually complementary cylindrical surfaces at 22 and 12 respectively. More specifically, when seen in cross-section, arranged around the periphery of the roller body 10 are circular projections 12 which are connected integrally with the main part 16 of the roller body 10 through the intermediary of a flanged web 14. As will be seen from Figure 3, the recesses 22 in the drive elements 20, said recesss being complementary to the circular projections 12, have a diameter which is greater than the diameter of the projections 12, as will be explained in more detail below. The spring elements 40 are produced from an appropriate extruded rubber material and have a wedge-shaped cross-section, wherein the wedge-shaped surfaces 42 of said spring elements abut with similarly wedge-shaped outer sides 32 of the adjacent drive elements 20. The bottom surfaces 44 of the spring elements 40 rest against the outer surface of the main part 16 of the roller body 10. Abutting the rounded top of each spring element is a projection 24, 26 formed on the outer sides of the drive elements 20. Each drive element is provided on its upper side with a pair of mutually spaced, pointed engagement edges 28, 30 (Figure 4), which may also be provided with recesses 36 so as to form a plurality of drive teeth 34, as shown in Figure 2. It will also be seen from Figure 2 that at least two drive elements 20 can be fitted on each projection 12. The drive elements 20 and the rubber elements 40 are held in position on the roller body 10 by means of the two annular side walls 60, the radially outer parts 62 of which (Figure 2) prevent the drive elements 20 and the spring elements 40 from sliding off the roller body 10. The side walls 60 are connected to the roller body 10 by means of screws 64, which are screwed firmly into screw-threaded holes 18 (Figure 3) on the circular projections 12 of the roller body 10. As shown in Figure 2, the annular hub plate 50 is connected to the roller body 10 by means of a welded joint 54 and is provided with a plurality of attachment holes 52 for attachment of a drive hub (not shown) of a hydraulic motor, for instance. In the non-loaded state of the feed roll (shown in Figure 1), the drive elements 20 are biased radially outwards by the spring elements 40, so that the recesses 22, at their openings, abut the projections 12 of the roller body in the vicinity of the flange webs 14. Because the recesses 22 are wider, or have a greater diameter than the projections 12 when subjected to load, the drive elements 20 are able to move to a limited extent relative to the projections 12, against the action of the spring force exerted by the spring elements 40. As will be seen from Figure 3, which illustrates a number of drive elements subjected to load by a tree trunk 70, these movements may include both limited translatory movements and limited pivotal movements around associated projections or arms 12. Because the drive elements 20 are elastically mounted in the roller body 10, in the aforedescribed manner, the drive teeth are able to adapt to irregularities in the periphery of the tree trunk and therewith improve the driving engagement of said teeth, as distinct to the case of a so-called spiked roller for instance, in which the drive elements are connected rigidly to the roller.

Claims: A feed roller for use in timber processing units, comprising a roller body having disposed around its outer periphery elastically supported engagement devices for driving engagement with a tree trunk advanced by the roller, the engagement devices including separate elements (20) each of which is connected to the roller body, characterized in that (a) the engagement devices (20) are connected to the roller body (10) by means of groove joints (14,22) which exhibit play, and (b) the elastic support is obtained by means of separate spring elements (40) positioned between and supporting mutually adjacent engagement devices wherein the spring elements are supported on their bottom surfaces by the roller body (10), wherein (c) the spring elements are tapered in the radial direction of the feed roller, wherein the wedge-shaped surfaces (42) of the spring elements abut the inclined surfaces (32) of adjacent engagement devices in order to press them within the extent of the play of the joint away from the roller body (10). A feed roller according to claim 1, characterized in that at least one and preferably all of the roller body (10), engagement devices (20) and spring elements (40) have form which enables them to be produced by continuous casting processes.

Inventors: ARVIDSSON HANS, ARVIDSSON, HANS
Applicants: GRANGAERDE MASKIN AB
Application year: 1991
Main classification: B27B25
IPC codes: B27B25