Classifications

• • 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
  • B27L11/00—Manufacture of wood shavings, chips, powder, or the like; Tools therefor
  • B27L11/005—Tools therefor

Definitions

• the present invention is concerned with a chipper for the chipping of wood.
• the chipper in accordance with the invention is suitable for chipping of slender trees.
• Such slender trees are harvested in connection of thinning and cleaning of forests, and such wood is usually of excessively little dimensions to be used for any other purpose except for firewood. This is why it is preferable that the wood material is recovered as completely as possible, i.e. including the twigs, leaves, and needles.
• Lath chippers are, however, not very well suitable for the said purpose, for the construction of their chipping member usually requires forced feeding of the lumber to be chipped. Separate forced-feeding devices make the chipper unnecessarily heavy for cross-country con ⁇ ditions, e.g., for operation by means of an ordinary agricultural tractor.
• the chipping member of these chippers has been planned for chipping of raw-material suitable for pulp mills, i.e. of chips of relatively little dimensions.
• the chips of the said sort are not very well suitable, e.g., for grate boilers, because the small-size chips are packed on the grate as a dense heap, through which the combustion air cannot penetrate to a sufficient extent.
• the chipper member consists of a cutter blade as screw-shaped surrounding the shaft that receives the operating power, the perpen ⁇ dicular distance of the said blade from the shaft increasing in the direction of feed of the wood.
• the cutter blade forms a spiral cone expanding in the direction of feed of the wood, the sharpened outer edge of the said spiral cutting through the wood by pressing it against a guide formed into the feed trough.
• a chipper By means of the chipper construction in accordance with the present invention, a chipper has been provided which is particularly well suitable for the chipping of slender trees, in which the automatic feed of the wood is highly efficient, in which the trees have a steady behaviour throughout the entire cutting process, and by means of which the chipping can be achieved with a lower power requirement as compared with the prior-art chippers.
• the chipper in accord ⁇ ance with the invention which, in a way in itself known, comprises feeding members, such as a trough for feeding the wood to be chipped, a chipping member supported and rotated by the shaft receiving the operating power, as well as, preferably, members for the removal of the chips, such as a blower supported and driven by the said shaft, as well as an exhaust tube, and in which chipper the chipping member consists of a blade disc,which is mounted perpendicularly and centrally on a shaft, as well as of a chipping blade or blades mounted on the blade disc, is characterized in that the chipping blade consists of at least one continuous blade projecting
• Figure 1 shows a chipper in accordance with the invention as viewed from above, partly in section.
• Figure 2 shows the chipping member of the chipper as mounted on the drive shaft
• Figure 3 shows the chipping member as viewed out of the direction of introduction of the drive power for the shaft.
• Figure 4 shows a detail of the relative fitting between the final cutting edge of the blade and the counter-blade formed into the feed tube, as seen perpendicularly to the direction of the drive shaft, and
• Figure 5 shows a detail of the portion in the side wall of the feed tube at which the counter- blade of the final cutting edge of the cutting blade has been formed.
• the chipper shown in Fig. 1 is in itself known, i.e. it comprises a tube-shaped or trough-shaped feeding member 1 for feeding the wood to be chipped, a chipping chamber, in which the chipping member 3 supported by the driven shaft 2 performs the chipping of the wood fed in as well as feeds the wood further to the chip-removing members.
• the removing members preferably consist of a blower unit 4 supported and driven by the same shaft 2 as well as of an exhaust tube 5 guiding the out-coming chip flow.
• the chipping member 3 consists of a blade disc 6, which is mounted on the drive shaft 2 centrally and perpendicularly to the shaft.
• the blade 7 that performs the cutting is formed as a spiral mounted on the blade disc, at which spiral the edge projecting from the blade disc is sharpened as a cutting edge 7' .
• the blade spiral projects as substantially perpendicular from the face of the blade disc, i.e. as substantially parallel to the drive shaf 2.
• the blade spiral 7 starts from the circumference of the blade disc and approaches the centre of the blade disc as spiral- shaped, preferably to a distance that is about 1/4 of the diameter of the blade disc.
• the cutting edge of the blade spiral becomes more distant from the face of the blade disc as screw-shaped to a distance corresponding to a full cutting stroke, i.e. to a distance at which the cutting edge meets the wall plane of the feed trough.
• the length of the blade spiral and, at the same time, also the thread-shaped pitch of its cutting edge have been selected so that the blade performs a full cutting stroke during about 1 revolutions of the blade disc.
• the blade starts a new cutting operation before the preceding cutting operation has been completed, which stabilizes the cutting process and ensures continuous and undisturbed feed of the wood.
• the masses of the blade have also become dynamically substantially balanced.
• a starting edge 7" of steeper pitch is formed at the beginning of the steel spiral, which starting edge begins the cutting of the log by striking a starting cut into it, into which said starting cut the blade edge 7' proper then cuts in.
• the dynamic balance of the blade device In the dimensioning of the blade, the dynamic balance of the blade device must, of course, also be taken into account, for the machine will revolve at quite a high speed of revo ⁇ lution, which, as attached directly to the power take ⁇ off of a tractor, will be about 540 rpm.
• revo ⁇ lution which, as attached directly to the power take ⁇ off of a tractor, will be about 540 rpm.
• the said counter-blade groove prefer ⁇ ably extends across the entire feed trough, as is shown in Fig. 5.
• Fig. 5 also shows the grooves 9 formed in the feeding direction in the side wall of the end portion 1 ' of the trough 1 at the side of the final cutting counter-blade 8, the objective of' the said grooves being to guide the trees to be chipped so that they should not be turning at the final stage of the chipping.
• the said grooves may, of course, be replaced by corres ⁇ ponding ribs.
• the chipper in accordance with the invention operates very smoothly, i.e. the feeding of the wood into the chipper takes place at a uniform speed and efficiently, without any tendency of the trees to toss around at any stage of chipping.
• the power requirement with a chipper in accordance with the invention when chipping a tree of equal thickness, is lower than when prior-art chippers are used.
• the favourable effects mentioned above are derived from the favourable cutting operation of the chipping member used in the chipper in accordance with the invention.
• the low consumption of power and the efficient feed are obviously mainly caused by the spiral form of the blade. According to the invention, when the steel spiral accomplished in the chipping
• the - ⁇ lJRE member bites itself in accordance with the pitch of the screw line of the cutting edge transversely into the wood, the blade becomes more steeply curved, as the spiral becomes narrower, in the longitudinal direction of the wood, whereat the blade presses the chip piece being cut apart in the transverse direction by means of the steepening inner portion of the blade in the feeding direction of the wood, which results in an increasing power component in the longitudinal direction of the wood in the direction cleaving the chip particle apart.
• the said longitudinal power component essentially con ⁇ tributes to the detaching of the chip particle, whereat the distance of cutting of the blade edge into the wood at each particular time remains short, as a result of which there is also a low rubbing-friction effect.
• this power component acts in the feeding direction of the wood and aids in the feeding of the wood, without any counter-component overruling this power component occurring in the cutting process, for the outer edge of the blade becomes constantly more distant from the corresponding edge of the cutting groove and, consequently, does not cause a rubbing resistance against this edge.
• Another essential factor that contributes to the steady behaviour of the wood in the chipper is the fact that the cutting blade is a tangent to the log at a substantially little angle, which corresponds to the pitch angle of the screw line of the cutting edge, and not to the curve radius of the screw, as is the case in a prior-art spiral chipper.
• chipper in accordance with the present invention as compared with a prior-art chipper that the construction of the chipper member is essentially more advantageous in respect of the strength and the manufacture of the chipping member.
• the invention may also be accomplished by forming the blade 7 as a double spiral, which is placed on the blade disc 6 as of different phases.
• the double spiral gives better possibilities for making the choice between the desired chip size and the diameter of the blade disc of the chipper.

Landscapes

• Engineering & Computer Science (AREA)
• Life Sciences & Earth Sciences (AREA)
• Manufacturing & Machinery (AREA)
• Mechanical Engineering (AREA)
• Wood Science & Technology (AREA)
• Forests & Forestry (AREA)
• Debarking, Splitting, And Disintegration Of Timber (AREA)

Priority Applications (2)

Applications Claiming Priority (1)

Publications (1)

Family

ID=8516632

Family Applications (1)

Country Status (4)

Cited By (5)

Families Citing this family (1)

Citations (7)

• 1983
  • 1983-01-21 FI FI830202A patent/FI69981C/fi not_active IP Right Cessation
• 1984
  • 1984-01-23 DE DE8484900619T patent/DE3466488D1/de not_active Expired
  • 1984-01-23 WO PCT/FI1984/000008 patent/WO1984002871A1/en active IP Right Grant
  • 1984-01-23 EP EP19840900619 patent/EP0135519B1/en not_active Expired

Patent Citations (7)

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