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
  • B27L11/02—Manufacture of wood shavings, chips, powder, or the like; Tools therefor of wood shavings or the like

Definitions

• the invention relates to a method defined in the preamble of claim 1.
• the invention further relates to an apparatus defined in the preamble of claim 15.
• the cutter disc is fitted with bearings to rotate around the axis of rotation.
• the cutter disc is rotated by means of a power unit about its axis of rotation.
• a block of wood is fed by means of a feeder in its longitudinal direction against the cutter disc and the chipping blades comprised in it, whereby the chipping blades will cut wood chips from the end of the block of wood.
• a problem with this known chipping method is that the thickness distribution of the chips formed is extremely wide, that is, the chips contain both sawdust and wood chips in a great variety of sizes. In the sawdust the wood fibres have broken down. Knags, for their part, form thick pieces approximately the size of the tip of a thumb. The digestion of such chips in the pulping process is very uneven and the pulp obtained is non- homogeneous. Due to the non-homogeneous wood chips, more chemicals have to be used in the pulping process, which increases process expenses and the load on the environment, in other words, the consumption of energy and the amount of effluent.
• a further problem with the known method and apparatus is that the average length of the chips produced is relatively short.
• the chipping process is not controlled, because when fed longitudinally, a block of wood cannot be supported at the final stage of chipping.
• additional sawdust is formed, which further increases the amount of the small fraction and reduces fibre length.
• the cutter disc used in the chipping apparatus is very large and heavy.
• a conventional cutter disc weighs approximately 10 tons, has a diameter of approximately 3.5 m, and to use it is required an extremely high-powered and expensive electric motor (output about 3000 hp). Electric motors of this type are usually not serial production engines, which further increases their acquisition costs.
• the aim of the invention is to eliminate the above-mentioned disadvantages.
• the aim of the invention is especially to provide a chipping method and apparatus, the wood chips formed by which in chipping are improved compared with the current chips and are as optimal as possible, of uniform quality, of equal length and thickness and free of sawdust, whereby the chips are digested evenly in pulping and the pulp produced is homogeneous and of good quality.
• a further aim of the invention is to provide a chipping method and apparatus by means of which considerable economical savings can be made in pulping, the consumption of chemicals and energy can be reduced, and the load on the environment can be diminished.
• a further aim of the invention is to provide a method and apparatus by means of which a whole block of wood can be made, over its entire length, into wood chips of uniform quality and free of sawdust.
• a further aim of the invention is to provide an apparatus in which a serial production power unit can be used to operate the cutter disc.
• the method according to the invention is characterised by what is disclosed in claim 1.
• the apparatus according to the invention is further characterised by what is disclosed in claim 15.
• the chipping blades are arranged as blades cutting the wood according to the principle of planing, on the lateral face of the cutter disc, into a successive and overlapping formation in the directions of the radius of the cutter disc and the circumference in such a way that the chipping blades together form a continuous partial cutting section of predetermined length; a number of cutter discs are arranged in such a way that the axes of rotation of the cutter discs are mutually parallel and essentially on the same level and, as seen in the direction of the axes of rotation, the cutter discs are overlapping and successive with respect to each other so that the partial cutting sections of successive cutter discs form an elongated overall cutting section, the length of which equals essentially at least that of a block of wood to be chipped; the block of wood is fed in a transverse direction with respect to its longitudinal direction on the plane of the axes of rotation of the cutter discs or in its vicinity against the rotating cutter discs, whereby the chipping blades chip the block of wood over its
• the chipping blades are arranged as blades cutting the wood according to the principle of planing and fitted on the lateral face of the cutter disc, into a successive and overlapping formation in the directions of the radius of the cutter disc and the circumference in such a way that the chipping blades together form a continuous partial cutting section of predetermined length.
• the apparatus comprises a number of cutter discs which are arranged in such a way that the axes of rotation of the cutter discs are mutually parallel and essentially on the same level, and as seen in the direction of the axes of rotation, the cutter discs are overlapping and successive with respect to each other so that the partial cutting sections of successive cutter discs form an elongated overall cutting section, the length of which equals essentially at least that of a block of wood to be chipped.
• the feeder is arranged to feed the block of wood against the cutter discs in a transverse direction with respect to its longitudinal direction on the plane of the axes of rotation of the cutter discs or in the vicinity of the said plane, whereby the chipping blades in the cutter discs chip the block of wood over its entire length.
• An advantage of the invention is that when the block of wood is fed against the chipping blades in a transverse direction with respect to the longitudinal direction of the block of wood and the wood chips are planed with small- sized chipping blades from the face of the wood in the direction of the fibres, the wood chips produced will be of equal length and thickness and very little sawdust is formed. The knags are also formed into essentially similar chips as the other parts of the wood, which means that no chip finishing will be required, and thus the need for a finishing plant is eliminated. By arranging a suitable number of cutter discs in succession and in an overlapping manner, each cutter disc will in turn plane from the block of wood a piece having the same length as the partial cutting section into wood chips.
• a single cutter disc does not have to be as large, and the power unit driving it does not have to be as powerful, as in the known chipping apparatus, which means that a commercially available standard power unit, for example, a standard electric motor, can be used. Due to the smaller size, the manufacture of the apparatus becomes easier and less expensive.
• the number of cutter discs is selected in such a way that the overall cutting section formed by the successive partial cutting sections of the cutter discs will be long enough for the block of wood to be chipped over its entire length.
• the chipping process is well controlled. The digestion properties of the chips formed are optimal, whereby considerable savings in costs can be made in pulping.
• chipping blades in the cutter disc are arranged chipping blades that are on the lateral face of the cutter disc, and an edge chipping blade, which is outermost on the edge of the circumference of the cutter disc in the direction of the radius, and extends somewhat over the edge of the outer circumference of the cutter disc.
• the chipping blades are arranged on the cutter disc into an arched formation, which curves in the direction of the radius of the disc cutter towards the circumference and in the direction of the circumference, in the opposite direction with respect to the direction of rotation.
• the formations are preferably arranged in pairs, symmetrically with respect to the centre of the disc.
• the cutter discs are arranged to be mutually essentially identical.
• the cutter discs are rotated around their axes of rotation in the same direction of rotation, at essentially the same speed of rotation.
• the number of cutter discs is selected so that the length of the overall cutting section becomes equal to at least the standard maximum length of a block of pulpwood. In such a case, the blocks of wood do not have to be cut. In one embodiment of the method, the length of the overall cutting section is greater than 5 metres, because the standard maximum length of Finnish pulpwood (softwood) is 5 metres. If the block of wood is halved before chipping, it suffices that the length of the overall cutting section is greater than 2.5 metres.
• the block of wood is supported laterally from opposite sides while feeding it against the cutter discs.
• the block of wood is pressed on opposite sides when feeding it against the cutter discs.
• the projection of the chipping blade from the lateral face of the cutter disc is adjusted to adjust the thickness of the wood chips.
• a set of chipping blades of different widths is provided and chipping blades of suitable widths are selected for the cutter disc to adjust the length of the wood chips to be optimal in accordance with the fibre length of the type of wood to be chipped.
• chip Finnish pulpwood softwood
• chipping blades that are fitted to produce wood chips having a length of approximately 4 cm.
• the optimum length of wood chips is approximately 4 cm, in which case the proportion of broken fibres in the pulp will be as small as possible.
• the chipping blades are adjusted so that they will produce wood chips that are approximately 4 mm thick. A chip thickness of approximately 4 mm is optimal.
• the formation of chipping blades in the cutter disc comprises chipping blades which are on the lateral face of the cutter disc, and an edge chipping blade, which is outermost on the edge of the circumference of the cutter disc in the direction of the radius, and extends somewhat over the edge of the outer circumference of the cutter disc.
• the chipping blade comprises a straight planing edge which is arranged in the radial direction of the cutter disc to plane the wood chips off the wood in the direction of the wood fibres, and a cutting edge which extends from the end of the planing edge, at an angle with respect to the planing edge, in order to cut the wood chips.
• the chipping blade comprises two cutting edges located symmetrically on either side of the planing edge.
• the angle between the planing edge and the cutting edge is 40° - 50°, preferably 45°.
• angles of cutting of the planing edge and the cutting edge are approximately 35°.
• a cutting blade provided with a score edge to cut the so- called end chip.
• the end chip is referred to the last chip in the partial cutting section which has to be detached from the block of wood by means of a cutting blade.
• the chipping blades are arranged on the cutter disc into an arched formation, which curves in the direction of the radius of the disc cutter towards the circumference and in the direction of the circumference, in the opposite direction with respect to the direction of rotation.
• the cutter discs are mutually essentially identical.
• each cutter disc is provided its own power unit.
• the power units are arranged to rotate the cutter discs around their axes of rotation in the same direction of rotation, at essentially the same speed of rotation.
• the number of cutter discs is selected so that the length of the overall cutting section becomes equal to at least the standard maximum length of a block of pulpwood.
• the length of the successive cutting sections is greater than 5 metres, that is, greater than the standard maximum length of Finnish pulpwood (softwood). If the block of wood is halved before chipping it suffices that the length of the overall cutting section is greater than 2.5 metres.
• the feeder comprises a first support device, which is arranged to support the block of wood from a first direction and a second support device, which is arranged to support the block of wood from the opposite direction with respect to the first direction.
• the first support device is a conveyor, such as a chain conveyor, onto which the block of wood can be placed so as to be horizontal.
• the second support device comprises a compressing device for pressing the block of wood against the first support device.
• the apparatus comprises fastening means for fastening the chipping blades to the cutter disc, by means of which fastening means the projection of the chipping blade from the lateral face of the cutter disc can be adjusted.
• the fastening means are pressure medium operated quick-release means.
• the apparatus comprises a set of chipping blades of different widths, the cutting widths of which are fitted to be optimal in accordance with the fibre length of the type of wood to be chipped.
• the set comprises chipping blades, the width of which is fitted to produce wood chips having an optimal length of approximately 4 cm.
• the projections of the chipping blades from the cutter disc are adjusted so that they will produce wood chips having an optimal thickness of approximately 4 mm.
• Figure 1 shows diagrammatically a perspective view of one embodiment of the apparatus according to the invention
• Figure 2 shows the apparatus of Figure 1 as seen from the direction of feed of the block of wood
• Figure 3 shows the apparatus of Figure 2 as seen from direction III-III
• Figure 4 shows perspectively a chipping blade
• FIG. 5 shows the section V-V of the chipping blade shown in Figure 4,
• Figure 6 shows a longitudinal section of the chipping blade when attached to the cutter disc
• Figures 7 and 8 show perspectively an edge chipping blade and a cutting blade when attached on the edge of the cutter disc.
• Figures 1 to 3 show an apparatus by means of which wood can be chipped without producing sawdust into wood chips of optimal size, which are optimal for the pulping process.
• the apparatus comprises a number of mutually identical cutter discs 1, of which there are four in this example.
• Each cutter disc 1 comprises a number of chipping blades 2.
• the cutter discs 1 are fitted with bearings to rotate around the axis of rotation, and for rotating each cutter disc 1 are arranged power units 5, which may be, for example, electric motors equipped with reduction gears.
• the power units 5 rotate the cutter discs at the same speed in the same direction of rotation as shown in the figure by arrows A.
• the chipping blades 2, 2' are blades that cut wood according to the principle of planing. They are arranged on the lateral face P of the cutter disc 1, into a successive and overlapping formation in the directions of the radius of the cutter disc and the circumference in such a way that the chipping blades 2 together form a continuous partial cutting section 3 of predetermined length.
• the cutter discs 1 are arranged in such a way that the axes of rotation of the cutter discs 1 are mutually parallel and essentially on the same level.
• the cutter discs 1 are overlapping and successive with respect to each other as seen in the direction of the axes of rotation.
• the partial cutting sections 3 of successive cutter discs 1 form an elongated overall cutting section 4, which is essentially at least the length of the block of wood to be chipped.
• each cutter disc 1 will in turn plane a piece from the block having a length corresponding to the partial cutting section 3.
• the apparatus are provided in succession and in an overlapping manner so many cutter discs 1 that the length of the overall cutting section 4 will be equal to or greater than 5 metres, in which case the chipping blades 2, 2' in the cutter discs 1 will chip the block of wood over its entire length.
• the feeder 6 shown in Figures 2 and 3 is arranged to feed the block of wood against the cutter discs 1 in a transverse direction with respect to the longitudinal direction of the block of wood (as shown in Figure 1) on the plane of the axes of rotation of the cutter discs (1) or in the vicinity of this plane.
• the feeder 6 comprises a first support device 11, such as a motor- driven chain conveyor, onto which the block of wood can be placed so as to be horizontal, so that it will support the block of wood from below.
• the second support device 12, which comprises a compressing device 13, such as suspension or the like, is arranged to force the block of wood against the conveyor 11.
• the arched formation of chipping blades comprises the type of chipping blades 2 shown in Figure 4, which project from the lateral face of the cutter disc 1, as shown in the sectional view 6.
• an edge chipping blade 2' On the edge of the cutter disc 1 is, in addition, an edge chipping blade 2', as shown in Figures 8 and 9, which is outermost on the edge of the circumference of the cutter disc 1 in the direction of the radius, and extends somewhat, for example about 4 mm, over the edge of the outer circumference of the cutter disc.
• a cutting blade 10 provided with a score edge 9 for cutting the so-called end chip. In this way, the chipping blade 2' will form chips over the circumferential edge of the cutter disc.
• each chipping blade 2 and 2' has a straight planing edge 7.
• the chipping blades 2, 2' are on the cutter disc 1 in an arched formation as shown in Figures 1 and 2, in such a way that the straight planing edges 7 are parallel with the radial direction of the cutter disc 1.
• Figures 1 and 2 show how the arched formation of the chipping blades 2, 2' curves in the radial direction of the cutter disc 1 towards the outer circumference, and in the direction of the circumference in the opposite direction with respect to the direction of rotation of the cutter disc
• Each cutter disc 1 has two formations symmetrically with respect to the centre of the disc.
• the planing edges 7 of the chipping blades 2, 2' plane the wood chip off the wood in the direction of the wood fibre.
• the angles of cutting ⁇ of the planing edge 7 and the cutting edge 8 are approximately 35°, as seen in Figures 5 and 6.
• At either end of the planing edge 7, at an angle ⁇ 45° with respect to it, are the cutting edges 8 for cutting the wood chips.
• the wood being chipped is Finnish pulpwood (softwood)
• the set may include chipping blades 2, 2' having a cutting width adjusted differently for Nordic and tropical species of wood having different fibre lengths.
• Figure 6 shows a bolt attachment 14 of a chipping blade 2 to a cutter disc 1, but hydraulic quick-release means are preferably used for attaching the chipping blades 2, 2', by which quick-release means all blades can be detached at the same time from the cutter disc for maintenance and sharpening.

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• 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)
• Crushing And Pulverization Processes (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (1)

Family

ID=8561716

Family Applications (1)

Country Status (3)

Citations (3)

Family Cites Families (1)

• 2001
  • 2001-08-08 FI FI20011615A patent/FI111448B/sv active
• 2002
  • 2002-08-07 DE DE10296843T patent/DE10296843B4/de not_active Expired - Fee Related
  • 2002-08-07 WO PCT/FI2002/000655 patent/WO2003013807A1/en not_active Application Discontinuation

Patent Citations (3)

Non-Patent Citations (1)

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