BACKGROUND OF THE INVENTION

This invention relates to comminutcrs, and more particular to an impact rotor assembly for reducing large diameter wood procucts and stumps to size.

Impact crushers for the reduction and classification of or utilizing an impact rotor to obtain the initial reduction of large ore chunks are known in the prior art. See U.S. Patent No. 3,887,141 to P. M. Francis. Francis discloses a mill in a single housing. A primary reduction chamber located within th housing is fed raw ore with variable particle sizes up to and including chunks on the order of 1 foot in diameter. An impac rotor is positioned within the primary reduction chamber and secured to the output shaft of a drive motor. The impact roto mc ntε a plurality of elongated hammer bars around in=. periphery. These hammer bars are oriented parallel to the rotational axis of the impact rotor. The rotor is positioned that the ore, falling under the influence of gravity, is directed against the hammer bars and repelled therefrom with great force against the sides of the primary reduction chamber

Application of Francis-type pulverizing mills to wood waste is also known . See U . S . Patent No . 4 , 151 , 959 to C. L . Deister The Deister patent discloses an impact pulverizer having a roto located concentrically within a reduction chamber. The rotor has a plu rality of generally radially-extending impact blades . The radial angle of the blades increases along the axis of the rotor to provide each of the blades with a slope in the axial direction of the rotor. The spi ral rotational action of the pieces as they are propelled and ricocheted around the primary reduction chamber achieves a faster pulverizing action than Francis-type pulverizing mills . The spiral rotational action also requi res less power that the Francis mill .

Prior art pulverizing mills are ineffective in reducing log because the wood is not hard enough to shatter, i .e. , the resiliency of wood requires a shearing and grinding effect . Although neither the Francis nor the Deister mills arc able to reduce wood logs to size , the principal of the spiral Deister rotor has been applied to a rotary wood hog for reducing logs . Rawlings Construction Co . of Montana, markets a rotary wood hog which uses a helical rotor to reduce elongated wood products to size . By use of an anvil at the f ront of the rotary hog , the Rawlings helical rotor is able to shear and grind pieces of the log during each revolution of the rotor .

The increasing radial angle of the Rawlings rotor blades attempts to move the material being acted upon in a generally spiral rotational motion. Because logs are generally most efficiently fed into a rotary wood hog at lengths of ten feet more and in a direction where a log's longitudinal axis is parallel to the rotor's radial axis, the spiraling action of t rotor blades will move the end of the log being acted upon by the rotor toward one corner the reduction chamber. The log being reduced will thereby tend to change from an upright vertical position to a horizontal position frequently causing bridging-type jam when the length of the log matches the width of the rotor housing, i.e., the log will bridge the rotor and block additional material from reaching the rotor blades. Thi is especially a problem when dealing with larger diameter wood products, i.e., 24 inches to 40 inches because of the extensiv shut down required to remove the jammed pieces which are large and heavy. Even without jamming, uneven wear of the rotor blades will take place.

SUMMARY OF THE INVENTION

In view of the foregoing disadvantages inherent in the kno types of devices now present in the prior art, the present invention provides a shredder/crusher for reducing larger diameter wood products to size. As such, the general purpose

the present invention , which will be described subsequently in greater detai l , is to provide a shredσer/crusher which will nc~ jam when comminuting wood products .

To attain this , the present invention comprises in combination with a housing and a drive motor , a reduction chamber disposed within the housing . An infeed chute is connected at one end of the chamber and is adapted to feed larger diameter wood p roducts and stumps to the interior thereof .

An impact rotor is positioned concentrically within the reduction chamber and operatively connected to the drive motor . The impact rotor is formed with a plurality of horizontally elongated impact hammers at its pe riphery . The impact hammers are arranged in sets of impact hammer rows oriented at an angle to the rotational axis of the impact rotcr . Each set of impact hammers has one row of hammers having radial angles increasing along the rotor 's longitudinal axis in the axial direction of the rotor and a second opposing row of hammers having radial angles decreasing along the roto r ' s longitudinal axis in the axial di rection of the rotor . The rotor is positioned so that the elongated wood product or stump falling under the inf luence of gravity through the infeed chute is directed against the impact hammers , and repelled ahead of the rotor ' s rotational direction against an anvil formed along one side of the

reduction chamber. The impact hammer arrangement provides shearing of that portion of the wood product engaged by the ro of hammers. The action of each set of opposing rows of impact hammers on the wood product keeps the wcod product generally horizontally and vertically positioned at its point of entry thereby avoiding bridge jamming and uneven wear on the impact hammers. The reduced wood product is forced onto a grating positioned about the bottom of the chamber. The continuous rotation of the impact rotor will grind and press sheared piec of wood product through the grate openings to a desired size.

The instant invention overcomes Rawlings' tendency to jam when reducing larger diameter wood products while still taking advantage of Deister's shearing effect. The instant invention arrangement of impact hammers in sets with opposing rows resul in the log tending to stay in that same position relative to t rotor as when it first entered the reduction chamber against t anvil while the impact hammers shear the wood.

This together with other objects of the invention, along with various features of novelty which characterize the invention, are pointed out with particularity in the claims annexed hereto and forming a part of this disclosure. For a better understanding of the invention, its operating advantage and the specific objects attained by its uses, reference shoul be had to the accompanying drawings and descriptive matter in which there is illustrated a preferred embodiment cf the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a side plan view of one embodiment of a shredder/ crusher according to the present invention.

Fig. 2 is a side sectional view of the shredder/crusher.

Fig. 3 is a flattened diagrammatic view of the impact rotor of the present invention.

Fig. 4A is a side elevational view of the first rotor segment in Fig. 2.

Fig. 4B is a side elevational view of the middle rotor segment in Fig. 2.

Fig. 4C is a side elevational view of the last rotor segment in Fig. 2.

Fig. 5 is a side sectional view of another embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the drawings in detail wherein like elements are indicated by like numerals, there is shown an embodiment o the invention 1 comprising a shredder/crusher with a rotary assembly for reducing large diameter wood products and stumps size. The present invention has a housing 10 with a top 11, bottom 12, front 13, back 14 and two sides 15, and a drive mot 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 interio of the reduction chamber 25. Mounted interiorly of 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 cidss 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 shaf 85 expandable lock rings (not shown) bind the rotor outside

segments 52, 54 to the shaft 85. The body 60 of each segment 5 has a generally quadrilateral shape and is welded to each adjacent segment 51. The side faces 61 of the segments 51 are ground absolutely flat and the resulting friction between the side faces 61 of adjacent segments 51 will help keep the rctcr segments 51 turning together without slippage and also provides for perfect alignment of each segment's central radial shaft opening 55. Each segment 51 is as wide as possible. In this embodiment, a 60 inch rotor length embodiment is illustrated containing five axial segments 51, each of which is 12 inches wide. In this embodiment of the invention each axial segment 51 has a main body 60 and four generally radially extending impact hammers 62 about its periphery 57. The impact hammers 62 also form a seat portion 64 for a striker plate 110. Each impact hammer 62 has two threaded holes 63 for bolting a striker plate 110 with two corresponding holes 113 to the front face 65 of the hammer 62. The front face 65 of a hammer 62 is defined as that side facing in the counterclockwise direction of impact rotor 50 rotation as shown in Figs. 1 - 5. Each striker plate 110 is attached to a hammer front face 65 by means of a bolt 114 inserted through each striker plats hole 113 into a corresponding impact hammer hole 63. The bolt holes 113 and 63 are positioned as low as possible on the hammer 62, i.e., close to the axial segment main body 60. The bolts 114 are threaded

and are held in place by cooperation of their threads with the hammer hole 63 threads. Alternatively, each bolt 114 could be held in place by means of a nut 115 on the back side 66 of the hammer 62.

The axial segments 51 are so arranged about the shaft 85 that the impact hammers 62 are formed into sets 67 cf impact hammer rows 68, 69 and oriented at an angle to the countei— clockwise rotational axis of the impact rotor 50. Each set 67 of i Dact hammers 62 has one longitudinal row 68 of impact hammers 62 having radial angles increasing along the rotor's longitudinal axis in the axial direction cf the rotor 50 and a second opposing row 69 of impact hammers 62 having radial angl decreasing along the rotor's longitudinal axis in the axial direction of the rotor 50. The radial angle of increase and decrease which provides the best shearing is 15 degrees. As rotor length increases, the radial angle may decrease to approximately 10 degrees. The maximum radial angle range appears to be 5 degrees to 25 degrees.

This arrangement of sets 67 and rows 68, 69 is illustrated diagrammatically in Fig. 3. To better understand the rotor segment configuration, Figs. 4A-4C illustrate the two end segments 52 and 54 as well as the middle segment 53 of the present five segment embodiment and should be examined in

conjunction with Fig. 3. The second and fourth segments are nci; shown. The first segment 52 is the segment 51 fully visible in Fig. 2.

The rotor 50 is centrally positioned within the reduction chamber 25 so that the elongated wood product or stump falling under the influence of gravity through the iπfεsd chute 20 is directed against the striker plates 110 attached to the impact hammers 62, and repelled ahead of the rotor's rotational direction against an anvil 70 formed along the upper front portion 33 of the reduction chamber 25. The anvil 70 has a wear plate 78 attached to its rearward face 77. The impact hammer arrangement of the present invention shears that portion of the wood product engaged by the impact hammer striker plates 110 and the anvil bottom 71. In the present invention's nominal 60 inch rotor, the impact rotor 50 rotates at a rate of 400 revolutions per minute- This provides 1600 hammer row hits on the wood product per minute. The effect of this is that the action of the opposing rows 68, 69 of impact hammers 62 in each set 67 on the wood product keeps the wood product generally positioned vertically and horizontally at the same relative point where it initially entered thereby avoiding jamming and uneven wear on the impact hammers striker plates 110.

The reduction chamber 25 has an upper portion 30 and a low portion 40. The rotor shaft 85 is horizontally and centrally positioned between the upper and lower portions 30, 40 transversely extending across the reduction chamber 25. The upper reduction chamber portion 30 has a quadrilateral polygon shape and has a top 31, bottom 32, front 33, back 34, and two sides 35. The upper portion top 31 opens ana is connected to the bottom 21 of the infeed chute. The striker plate top 111 opposing striker top 111 segment diameter of the impact rotor is slightly less than the front 33 to back 34 length of the reduction chamber upper portion 30. As stated above the upper portion has an anvil 70 formed along the upper front portion 3 of the reduction chamber 25. The anvil 70 acts as a countei— weight and shearing surface aid for the rotor 50. Because woo is so resilient, the anvil 70 must be an absolutely solid surface. In this embodiment the anvil 70 is made of steel and is 12 inches thick and approximately 60 irnches wide. A one in thick wear plate 78 is attached to the rear surface of the anv 70. The direction of rotation of the impact rotor 50 is counterclockwise towards the anvil 70. Wood product is thrown against the anvil wear plate 78 by the striker plates 110. Th anvil-backed wear plate 78 then momentarily holds the wood product in place while the impact hammer-backed striker plates 110 shear portions of the wood product as the striker plates 1

by the bottom 71 of the anvil 70 and wear plate 78. The anvil bottom 71 has a small vertical flange 72 on each side 73. The flanges 72 p rotrude through the housing f ront 13 and are connected to the housing f ront 13 by means of shear bolts 74 . The advantage of this arrangement over prior art devices is that the sheared bolt 74 can be easily removed . P rio r art devices usually have the shear bol ts threaded into the side 73 of the anvil plate 70.

Across the reduction chamber upper portion back wall 34 a wedge shaped piece 38 having a quadrilateral cross section is attached . The pu rpose of the wedge 38 is to keep logs f rom hitting the impact hammers rows 68 , 69 on the vertical upward portion of thei r rotation cycle and being thrown back out of the infeed chute 20. The quadrilateral shape eliminates a "shelf " for material to land upon .

the reduction chamber lower po rtion 40 also has a generally quadrilateral polygonal shape and has a top 41 , bottom 42 , f ront 43 , back 44 , and two sides 45. The lower portion top 41 opens up to and forms the upper portion bottom 32. A cu rved grate assembly 90 comprised of a f rame 98 and grate insert 99 is positioned along the lower periphery 57 of the impact rotor 50 for passing comminuted mate rial of a desi red size. The g rate 90 is connected at one end 91 at the approximate junctu re of the

upper and lower portion front walls 33, 43 just below the anv 70, and at its other end 92 at the approximate juncture of the upper and lower portion back walls 34, 44. As the wood produc is sheared, the reduced wσoα product is pushed onto the grate 90. The rotating impact rotor 50 will press the reduced wood product through the grate 90. The residue of reduced wood proαuct which does not pass through tne grate 90 is returned b the impact rows 68, 69 to the reduction chamber upoer portion 30. The residual wood product is thrown against the wedge's lower side 39 and then again against the anvil 70 and wear pla 78 for further reduction. The grate 90 is connected at its re end 92 by means of a removable hinge bolt 93. The grate front end 91 is connected by means of two removable shear bolts 94. In case of a serious jam the shear bolts 94 will break thereby releasing the grate 90 and preventing damage to the grate and impact rotor 50. The bolts 93 and 94 are removable to permit removal of the grate insert 90 and reinstallation in the rever direction. Since the grate insert holes (not shown) wear i a front to rear direction, reversal avoids the necessity of immediate replacement of the entire grate 90 because of wear. Grates 90 under this arrangement will last twice as long.

Although the present invention is designed primarily for u with larger diameter wood products, it may also be used for other typical pulverizable materials. When pulverizable

materials such as concrete wi th reinforced ba rs are to be reduced , the present invention may have two options added . As may be seen in Fig . 5 a blade spring 75 is attached horizontall across the anvil ' s forward face 76 and attached to the housing f ront 13. The anvil ' s rearward face 77 has the wear plate 78 against which the pulverizable material is hammered . Use of the blade spring 75 will allow the anvil 70 to f lex du ring comminu¬ tion cf particularly hard materials and thereby decrease the potential for jamming. The invention 's grate 90 is also changed , especially when reducing concrete with reinforcing bars which do not lend themselves to reduction and must be removed f rom the pulverizer. The concrete and bars are substantially separated by the hammering action as described above . If the same grating was used as with wood product reduction , the bars would almost immediately jam up the grating insert 99. The wood reduction grate assembly 90 is therefore replaced with a parti?! grate assembly positioned to the f ront 43 of the reduction chamber lower portion 40. The grate insert openings 96 (not shown) are elongated with a longitudinal axis in the di rection or rotation of the impact rotor . A spring system 100 is installed between the grate assembly and f ront wall 43. The spring system 100 is joined to the partial grate assembly under su rface 97 and provides flexing as the reinforcing bars pass through , thereby substantially reducing the potential for jamming .

In the embodiments described above the axial segments 51 have a preferably solid main body 60 made of solid steel construction. Conventional air intake means are used within t reduction chamber.

It is understood that the above-described embodiments are merely illustrative of the application. Other embodiments may be readily devised by those skilled in the art which will embo the principles of the invention and fall within the spirit and scope thereof.