Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
  • B27B—SAWS FOR WOOD OR SIMILAR MATERIAL; COMPONENTS OR ACCESSORIES THEREFOR
  • B27B33/00—Sawing tools for saw mills, sawing machines, or sawing devices
  • B27B33/14—Saw chains
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
  • B27B—SAWS FOR WOOD OR SIMILAR MATERIAL; COMPONENTS OR ACCESSORIES THEREFOR
  • B27B17/00—Chain saws; Equipment therefor
  • B27B17/06—Chain saws mounted on a bow
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
  • B27L—REMOVING BARK OR VESTIGES OF BRANCHES; SPLITTING WOOD; MANUFACTURE OF VENEER, WOODEN STICKS, WOOD SHAVINGS, WOOD FIBRES OR WOOD POWDER
  • B27L1/00—Debarking or removing vestiges of branches from trees or logs; Machines therefor
  • B27L1/06—Manually- operated or portable devices for debarking or for removing vestiges of branches
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
  • B27L—REMOVING BARK OR VESTIGES OF BRANCHES; SPLITTING WOOD; MANUFACTURE OF VENEER, WOODEN STICKS, WOOD SHAVINGS, WOOD FIBRES OR WOOD POWDER
  • B27L1/00—Debarking or removing vestiges of branches from trees or logs; Machines therefor
  • B27L1/12—Debarking or removing vestiges of branches from trees or logs; Machines therefor using pliable tools, e.g. chains, cables
  • B27L1/127—Debarking or removing vestiges of branches from trees or logs; Machines therefor using pliable tools, e.g. chains, cables in the form of circulating endless elements, e.g. cutting chains

Definitions

• the present invention relates to a delimbing unit for a manual power saw comprising a saw chain and a chain guide attached to the power saw, with a longitudinal guide groove for guiding the saw chain which can he driven by means of the chain sprocket of the power saw.
• the working process associated with tree cutting by means of a manual power saw can substantially be subdivided into three operational phases, i.e. cutting the tree, delimbing by sawing off branches and cross-cutting of the trunk into suitable lengths. Of these operations none is more time-consuming than delimbing. Experience has shown that roughly 50 per cent of the cutting tine is used for delimbing. That so much time has to be expended on delimbing is partly due to the fact that the design of a conventional power saw is not appropriate to this particular operational phase.
• a power saw of conventional design is provided with a level, longitudinal chain guide projecting straight from the saw, i.e. the bar.
• the saw chain is guided in a track leading from the driving chain sprocket along the lateral edges of the bar back to the driving chain sprocket.
• one of the lateral edges of the bar is pressed against the sawing point.
• Sawing is accordingly effected across the bar, in the plane of the bar.
• the bar must be moved from branch to branch and at the same time to different points around the trunk. Normally delimbing is effected from a position at the side of the tree, with the bar substantially directed across the trunk.
• the bar is kept pressed against the limb or branch.
• the pressing-on force is provided to a larger or smaller extent by the person who handles the power saw twisting his body.
• the branches en the underside of the tree, which may cause jamming of the bar, this entails a working position which from the ergonomic point of view is definitely unsuitable and tiring.
• delimbing is a time-consuming operation, and this fact often leads to an especially high working speed during this operational phase.
• the higher speed and the inconvenient working position contribute to increasing the danger of accidents during the delimbing phase.
• a delimbing unit of the type described above characterised in that the chain guide extends forward from the casing of the power saw in the same way as a bar-shaped chain guide of conventional design and in that a nose section of the chain guide facing away from the casing has a laterally bent shape, as a result of which the saw chain is guided along a substantially semicircular track in a plane transverse to the forward direction, whereas the saw teeth of the saw chain are, along the nose section of the chain guide, pointing substantially forward.
• delimbing is considerably facilitated, inasmuch as the semicircular nose section of the chain guide is held against the trunk of the tree.
• the semicircular shape substantially encompasses half the periphery of the trunk.
• the saw chain teeth which point substantially forward along the nose section, simultaneously remove branches along half the periphery of the trunk as the power saw is moved along the trunk.
• the branches on the "lower" half of the periphery of the trunk are reached and sawn off. This further accelerates and simplifies the delimbing operation.
• fig. 1 is a side view of a delimbing unit in accordance with the invention attached to a schematically drawn power saw casing
• fig. 2 shows the unit represented in fig. 1 as seen from above
• fig. 3 gives a schematic view from the front of the unit represented in fig. 1
• fig. 4 shows a saw chain for use in the unit in longitudinal section as well as a cross-section of the combination. saw chain/ chain guide.
• Fig. 1 shows, in schematic form, a power saw casing 1 with roughly outlined, conventional handles 101, 102.
• a delimbing unit in accordance with the invention is attached to the saw casing.
• the unit comprises a chain guide 2 and a saw chain 3, 4 guided thereby.
• the saw chain runs in a closed circuit from the driving chain sprocket 11 of the power saw along an edge of the chair, guide and back to the driving chain sprocket.
• Links 3 of the saw chain are provided with a guide lug 6 moving within a guide groove 2; marked by a dashed line along the edge of the chain guide. Every other link 3 bears a saw tooth 10 and a chip ejector 10' located, in the driving direction, after the tooth.
• the chain, links are held together by steel rods 4 (see also fig. 4).
• the saw chain is driven by the driving chain sprocket in the direction of the arrow.
• Chain guide 2 consists of a substantially flat rail extending, in the shape of two legs 22, 23 from the power saw casing in the forward direction, which is marked by an arrow in the drawing, and thereupon obliquely downward and outward (see fig. 2). At its lower end each leg passes into a section 22' or 23', respectively, bent in a substantially circular way both upward and inward towards one another. The sections 22' and 23' meet transversely to the forward direction in section 24.
• the sections 22', 25' and 24 constitute a nose section of the unit.
• the nose section is, viewed from the front, substantially semicircular. During the delimbing process this semicircular shape is held against the round periphery of the tree trunk, the saw being moved forward in the direction of the arrow.
• teeth 10 of the saw chain point forward.
• teeth 10 are facing straight forward, along sections 22' , 23' forward and obliquely downward, and at the lowest points of sections 22', 25' downward. Due to the shape of the chain guide as described the saw accordingly acts along the entire nose section, as it is moved forward.
• the nose section of the chain guide is so dimensioned that its semicircular shape corresponds substantially to half the periphery of trees of such size as normally cut.
• Fig. 1 shows also how the unit is attached to casing 1 of the power saw.
• Legs 22 and 23 of the chain guide are connected in the same plane by means of a retaining plate 26 with fastening devices 27, 28, 29, 30 appropriately adapted to chain guide fastening devices on a power saw casing of conventional design.
• plate 26 is secured to a movable part of the power saw (not shown) as is the case with a conventional chain guide.
• an adjusting screw not shown the movable part with the chain guide can be adjusted in known manner along slot 30 using pin 29 by way of control element. Thanks to this feature the saw chain can be tensioned as required.
• Plate 26 is provided with a lubricating point 31 connected via a duct 32 in plate 26 with that part of the guide track which extends along the lower edge of plate 26.
• Fig. 3 shows a protective device 25 enclosing the saw chain along leg 23 of the chain guide.
• a corresponding protective device is provided for section 22.
• the protective device 25 eliminates any risk of direct contact with the saw chain along the corresponding section of the chain guide.
• the schematic view of the chain guide in fig. 3 is primarily intended to illustrate the semicircular shape of the nose section of the chain guide .
• both the saw chain and l egs 22 , 23 have been omitted and power saw casing 1 has only been marked by dashed lines.
• Guide track 21 along the edge of the chain guide is marked by a dashed line.
• the saw chain is not loaded as it passes along leg 22, this being due to the direction in which it. is driven forward (see fig. 1).
• a saw chain to be able to run along chain guide 2 must be capable of being turned in all lateral directions and about its own longitudinal axis.
• Such a saw chain is known from the German laid open print 2758380. In this specification saw chains are described, the links of which are held together by means of ball and socket joints.
• a saw chain of this basic design is shown in fig. 4.
• the figure shows on the left the saw chain in longitudinal section and on the right in cross-section along line I-I, including also a cross-section of chain guide 2.
• Links 3 are held together by steel rods 4 both ends of which are rotatably fixed by means of ball and socket joints 5 in the corresponding links. Every other link bears a saw tooth 10 and a chip ejector 10 arranged next to it.
• the cross-sectional view shows guide track 21 in rail 2 of the chain guide.
• the inner shape of the guide track matches the outer shape of guide lugs 6 thus achieving a suitable sliding fit. So as to prevent the saw chain from sliding out of the guide track each guide lug 6 is provided with a link pin 8 projecting sideways.
• the side walls of guide track 21 are provided with longitudinal recesses, with the guide pins engaging the said recesses.
• the chain guide has a T-shape tapering from the chain links, which counteracts jamming of the chain guide

Landscapes

• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Wood Science & Technology (AREA)
• Forests & Forestry (AREA)
• Mechanical Engineering (AREA)
• Sawing (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=20342099

Family Applications (1)

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Family Cites Families (3)

• 1980
  • 1980-10-28 SE SE8007555A patent/SE8007555L/sv not_active Application Discontinuation
• 1981
  • 1981-10-27 WO PCT/SE1981/000316 patent/WO1982001503A1/en unknown
  • 1981-10-27 EP EP19810902949 patent/EP0063147A1/en not_active Withdrawn

Non-Patent Citations (1)

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