WO1996024436A1

WO1996024436A1 - Wood size reduction rotor

Info

Publication number: WO1996024436A1
Application number: PCT/US1996/001262
Authority: WO
Inventors: Anders T. Ragnarsson
Original assignee: Ragnarsson Anders T
Priority date: 1995-02-06
Filing date: 1996-02-01
Publication date: 1996-08-15
Also published as: AU4910596A

Abstract

An improved impact rotor for use in wood size reduction apparatus. The rotor (50) is formed with a plurality of identical rotor segments (51) having impact blades (110) at its periphery. The blades are arranged into four rows (67) of spaced impact blades helically disposed about the rotational axis of the impact rotor. The rows form alternate oppositely oriented helical blade arrays (68, 69) symmetrically disposed about the periphery of the rotor.

Description

'WOOD SIZE REDUCTION ROTOR

Background of the Invention This invention relates to comminutors, and more particularly to a rotor assembly for reducing large diameter wood products and stumps to size.

The most pertinent prior art known to Applicant is Applicant's own U.S. Patent 5,165,611 to Ragnarsson. That patent describes a co minutor for reducing large diameter wood products and stumps to size, comprised of a reduction chamber, with an impact rotor positioned concentrically therein, in combination with a housing, drive motor and infeed chute. The impact rotor is formed with a plurality of impact blades at its periphery and arranged in four blade arrays helically disposed about the rotational axis of the impact rotor. Two blade arrays have helical angles increasing along the rotor's longitudinal axis in an axial direction of the rotor while the other two blade arrays have helical angles decreasing along the rotor's longitudinal axis in the same axial direction of the rotor. The rotor is positioned so that the elongate wood product or stump falling under the influence of gravity through the infeed chute is directed against the impact blades, and repelled ahead of the rotor's rotational direction against an anvil formed along one side of the reduction chamber. Final assembly of the machine of U.S. Patent 5,165,611 requires the use of differently shaped rotor segments strategically located along the rotor. The result is significant expense in manufacturing and assembly cost. Ob-iects of the Invention

Accordingly, it is an object of the invention to provide a rotor having a plurality of substantially identical rotor segments while providing the advanced performance of the Ragnarsson machine disclosed in U.S. Patent No. 5,165,611.

Another object of the invention is to provide a rotor where each rotor segment has a pair of diametrically opposed blades.

Summary of the Invention:

According to the invention there is provided a rotor for comminuting wood by shearing, said rotor comprising plurality of identical rotor segments disposed side by side to define an axis of rotation, each said rotor segment having at least one radially extending blade support disposed on an outer periphery thereof, the identical segments being oriented about said axis thereby forming at least two helical arrays of impact blades with opposite helical twists about the axis, each array being coaxial with said axis and all blades supports being similarly oriented circumferentially about the axis.

According to the invention there is also provided a method of making a rotor for comminuting wood by shearing comprising the steps of a) providing a plurality of identical rotor segments, each said rotor segment having at least one radially extending blade support disposed on an outer periphery thereof; b) orienting said identical rotor segments about an axis of rotation to form at least two interrupted arrays of blade supports thereby producing oppositely angled helices, each array being coaxial wit said axis with all blade supports facing in the same

SUBSTITUTESHEET(RULE2B circumferential direction about the axis,- and, c) making said rotor segments fast relative to one another.

Brief Description of the Drawings Fig. l is an elevation of one embodiment of a prior art shredder/crusher to which the present invention relates,-

Fig. 2 is a diagrammatic sectional end of the shredder/crusher of Figure 1 with an impact rotor according to the present invention;

Fig. 3 is a flattened diagrammatic view of the impact rotor of the present invention showing the periphery of the rotor as if it had been unrolled; and

Fig. 4 is a end view of a rotor segment according to the invention.

Detailed Description of the Invention Referring to the drawings in detail, there is shown a shredder/crusher 1 with a rotary assembly for shredding large diameter wood products and stumps having a housing 10 with a top 11, bottom 12, front 13, back 14 and two sides 15, and a drive motor 5. A reduction chamber 25 is centrally disposed within the housing 10. A downwardly sloping infeed chute 20 is joined to the reduction chamber 25 and is adapted to feed large diameter wood logs, stumps and other wood products such as telephone poles, pilings, railroad ties, beams and posts, to the interior of the reduction chamber 25. Mounted inside the reduction chamber 25 is an impact rotor 50. The rotor 50 is carried on a shaft 85 which extends transversely across the reduction chamber 25, penetrates the housing sides 15 and is seated on bearings (not shown) bolted to support plates 86 bolted to the outside of the housing sides 15. One protruding end 87 of the shaft 85 is operatively connected to the drive motor 5 which provides rotational power to the shaft 85.

The impact rotor 50 is comprised of a plurality of axially contiguous, disk-like segments 51. When installed on the shaft 85, expandable lock rigs (not shown) bind the rotor to the shaft 85. The body 60 of each segment 51 has a generally circular shape and is welded to each adjacent segment 51. In this embodiment, a 60 inch rotor length is illustrated as having ten axial segments 51, each of which is 6 inches wide. Each axial segment 51 has a main body 60 and two generally radially extending blade supports 62 diametrically opposed on its periphery 57. The blade supports 62 each form a seat 64 for an impact blade 110 bolted to a front support face 65 of the support 62. The front support face 65 of a support 62 is that side facing in the counterclockwise direction when impact rotor 50 is oriented as shown in Figs, l and 2. Each impact blade 110 is bolted to a corresponding blade support 62 as close as possible to the main body 60. For clarity, only the four impact blades 110 on the first two rotor segments 51 of rotor 50 are shown in Fig. 2.

The axial segments 51 are so arranged about the shaft 85 that the impact blades 110 form four rows 67 of spaced impact blades helically disposed about the rotational axis 88 of the impact rotor 50. The rows 67 form alternate oppositely oriented helical blade arrays 68, 69 symmetrically disposed about the periphery of the rotor 50. This arrangement of sets 67 and rows 68, 69 is illustrated diagrammatically in Fig. 3 which illustrates the periphery of rotor 50 as if it had been unrolled. The helical angle of increase 89 and decrease 90, with respect to the axis 88, which provides the best shearing is 15 degrees. As rotor length increases, the helical angle may decrease to approximately 10 degrees. A satisfactory helical angle range appears to be from about 5 degrees to about 25 degrees. Fig. 4 illustrates one of ten substantially identical rotor segments 51 of the present ten segment embodiment. The rotor segments 51 are disposed along the rotor axis oriented to form interrupted (discontinuous) helical rows with alternate rows having opposite helical twists each with an angle of approximately 15°, as described above. The two axially centrally located rotor segments 51 are disposed 90° apart about the rotor axis with respect to each other. Outwardly from these central segments in either direction, the rotor segment 51 is oriented at appropriate angles about the axis to provide the desired helix angles.

With the arrangement shown, the segments 51 forming two interrupted diametrically opposed helical arrays of blades 110 having the same helical orientation (twist about the motor axis) are axially spaced apart by and alternate with the segments 51 forming the two interrupted diametrically opposed helical arrays of blades 110 having the opposite helical orientation, all blades facing in the same circumferential direction. A number of advantages become readily apparent in the present invention. For example, allowing a discontinuous helix results in the ability to use a plurality of identical rotor segments 51 to form rotor 50. Also, a discontinuous helix reduces the torque required to shred or shear the wood. Further, as can be seen best in Figs. 3 and 4, the support faces 65 may be machined parallel to the axis of rotation rather than at an angle equal to the helix angle. The result is reduced set up time and machining costs.

Fig. 4 shows a rotor segment 51 having two diametrically opposed blade supports 62 supporting impact blades 110. When a plurality of rotor segments 51 are assembled into a rotor 50, four helices are formed. Of course, should more than four helices be required, one need only increase the number of blade supports 62. For example, if each rotor segment contained four diametrically opposed blade supports 62, then a rotor 50 having eight helices can be formed. Broadly speaking, the number of helices desired equals twice the number of diametrically opposed blade supports 62.

The rotor segment 51 shown in Fig. 4 represents a typical rotor segment of the rotor 50. However, as will be apparent to one of ordinary skill in the art, shaft opening 55 may be appropriately bored on two rotor segments 51 to accommodated a desired end condition or attachment to shaft 85, using, for example, expandable lock rings (not shown) .

Claims

What is claimed is:

1. A rotor for comminuting wood by shearing, said rotor comprising: a plurality of identical rotor segments disposed side by side to define an axis of rotation, each said rotor segment having at least one radially extending blade support disposed on an outer periphery thereof, the identical segments being oriented about said axis thereby forming at least two helical arrays of impact blades with opposite helical twists about the axis, each array being coaxial with said axis and all blades supports being similarly oriented circumferentially about the axis.

2. A rotor according to claim 1 wherein an impact blade is mounted on said blade support.

3. A rotor according to claim 2 wherein each said impact blade is spaced from an adjacent impact blade of the same helical array by the thickness of an intermediate identical rotor segment the impact blade of which is a part of an oppositely twisted helical array of impact blades.

4. A rotor according to claim 2 wherein two axially central rotor segments are oriented 90° with respect to each other about the axis.

5. A rotor according to claim 4 wherein said rotor segments are fast with one another.

6. A rotor according to claim 2 wherein each rotor segment has two diametrically opposed impact blades.

7. A rotor according to claim 2 wherein said helical arrays are symmetrically disposed about the periphery of the rotor.

8. A rotor according to claim 2 wherein said helical angle of each array is in a range of from about 5° to about 25°.

9. A rotor according to claim 8 wherein said helical angle is 15°.

10. A method of making a rotor for comminuting wood by shearing comprising the steps of: a) providing a plurality of identical rotor segments, each said rotor segment having at least one radially extending blade support disposed on an outer periphery thereof; b) orienting said identical rotor segments about an axis of rotation to form at least two interrupted arrays of blade supports thereby producing oppositely angled helices, each array being coaxial with said axis with all blade supports facing in the same circumferential direction about the axis,- and, c) making said rotor segments fast relative to one another.

11. A method according to claim 10 comprising the step of mounting an impact blade on said blade support.

12. A method according to claim 11 comprising the step of spacing each said impact blade from an adjacent impact blade of the same helical array by the thickness of an intermediate identical rotor segment the impact blade of which is a part of an oppositely twisted helical array of impact blades.

13. A method according to claim 10 comprising the step of mounting an impact blade on each of said blade supports.

14. A method according to claim 10 comprising the step of symmetrically disposing said arrays about the periphery of the rotor.

15. A method according to claim 10 comprising the step of fastening said rotor segments directly to one another.

16. A method according to claim 10 comprising the step of orienting said rotor segments to form a helical angle in a range from about 5° to about 25°.

17. A method according to claim 16 wherein said helical angle is 15°.