US2796093A - Wood reducing apparatus with hold down attachment - Google Patents

Description

' June 18, 1957 A, MQTTET 2,796,093

WOOD REDUCING APPARATUS WITH HOLD DOWN ATTACHMENT Filed March 20, 1956 2 Sheets-Sheet 1 INVENTOR. Hrihur L. Moi 'l'e WOOD REDUCING APPARATUS WITH HOLD D OWN ATTACHMENT 2 Sheets-Sheet 2 Filed March 20, 1956 m .m. m m E Q g m H T u AQMQRMvH H M 1 fAr l-a V v av ll-.5 I

WOOD REDUCING APPARATUS WITH HOLD DOWN ATTACHMENT Arthur L. Mottet, Longview, Wash, assignor, by mesne assignments, to International Paper Company, New York, N. Y., a corporation of New York Application March 20, 1956, Serial No. 572,681

4 Claims. (Cl. 144-162) This invention relates to apparatus for defibering Wood, i. e. for reducing it to fibrous form, useful in bulk or in the manufacture of pressed fiberboard, such as insulation board or hardboard.

This application is a continuation-in-part of the application of Arthur L. Mottet, Serial No. 361,480, filed June 15, 1953 for Wood Defibering Apparatus.

In one important method of making hardboard, wood is reduced to the form of crosscut fibrous elements or flakes by cutting it, the cut being parallel to the grain direction and the direction of the cutting traverse being across the grain direction, preferably at about right angles thereto. The resulting crosscut flakes have lengths determined by the lengths of the knives employed or the spacing of scoring elements which may be employed in conjunction with the knives. Their thickness is determined by such factors as the setting of the knives, the feed rate, the number of knife strokes per unit time, etc.

The width of the flakes is random, depending upon the thickness of the pieces of wood from which they are cut, and the severity of subsequent handling operations which may break the flakes along the grain. To form them into fiberboard, the flakes are classified as to size, coated with a suitable binder, formed into a mat, and hot pressed to the desired density.

To obtain a hardboard product of maximum properties, it is essential that the defibering operation be controlled carefully to produce flakes of uniform dimensions. This is diflicult to do in commercial defibrators because of the high degree of vibration necessarily present; because of the difliculty of feeding the wood pieces at a uniform rate; and because of the tendency of the wood to splinter, particularly during the reduction of the last portion of each wood piece.

As a result, there is formed a conglomerate product of flakes having non-uniform dimensions together with slivers, splinters, and wood in granular and powdered form. When this is felted and pressed into hardboard, the resulting pressed product is correspondingly non-uniform in strength and density and is characterized by the presence of surface defects caused by the inclusion of sticks and slivers.

It therefore is a primary object of the present invention to provide apparatus which will produce fibrous elements from wood, particularly crosscut flakes, which are of predetermined dimensions and are relatively free from sticks and slivers.

It is another object of the present invention to provide apparatus for reducing wood which is adjustable easily and accurately to produce fibrous elements of the predetermined dimensions at the desired production rate.

Still another object of the present invention is the provision of wood defibering apparatus which is adaptable for use in the reduction to fibrous form of the woods of various species of trees and of various moisture content ranging from green wood to dry Wood.

Still another object of this invention is the provision of wood reducing apparatus which has a high production nited States Patent 2,796,093 Patented June 18, 1957 rate although the apparatus itself is relatively small in size and inexpensive to construct.

It is another object of the present invention to provide wood difibering apparatus adaptable for use in making crosscut, fibrous elements or flakes from kiln dry Wood scraps, such as planer ends. I p

Another object of the present invention is the provision of wood reducing apparatus which holds the wood securely during the cutting operation, making the same relatively safe while contemporaneously producing a fibrous product of high quality.

The manner in which the foregoing and other objects of this invention are accomplished will be apparent from the accompanying specification and claims, considered together with the drawings, wherein:

Fig. 1 is a fragmentary plan view of the presently described Wood reduction apparatus;

Fig. 2 is a view in side elevation of the apparatus of Fig. l; and

Fig. 3 is a detail sectional view taken along line 33 of Fig. 'l and illustrating the means of applying variable tension to the wood hold down means employed in the apparatus of Figs. 1 and 2.

As illustrated in the drawings the presently described wood reducing apparatus is provided With cutting means mounted on the frame 10 of the apparatus. Although the cutting means may comprise any suitable type of reciprocating or rotary cutter, it preferably comprises a rotary cutter head of the type indicated generally :at 12. In the body of the cutter head there are set at spaced intervals a plurality of knives 14. Alternating with the knives at spaced intervals about the periphery of the cutter head are the scoring points 16. These may be spaced apart as desired to determine the length of the fibrous elements cut from the Wood by the cutter head. A hopper 17 or other receiving means is placed below the cutter head for receiving the cut flakes and conveying them away from the apparatus.

The cutter head is rotatably mounted on a shaft 18, journaled in bearings 20. It is driven at the selected rotational speed by means of a constant speed motor not illustrated.

The blocks of wood 24 which are fed to the cutter head may be of any species and have any moisture content ranging from green wood to kiln dry wood. As has been indicated above, however, the apparatus is designed particularly for use with kiln dried wood scraps, such as planer ends, which are cut to pieces of substantially uniform length. These pieces are fed into a bed, the width of which is determined by a pairof elongated guide strips 26.

On the bottom of the feeding bed are a pair of spaced apart tracks 30, which are located within the guide plates 26, and are substantially parallel thereto. At the outfeed end of the feeding bed and adjacent the cutter head 12 is a bed plate 34 with soft metal insert 35 over which the wood pieces pass as they are reduced to fibrous form.

Hold down means are provided for holding down the blocks as they traverse the feeding apparatus and are acted upon by the cutter head. In the illustrated embodiment the hold down means comprises a floating hold down assembly including plate 36 which is dimensioned to overlie the wood blocks contained in the apparatus. It preferably is made of a heavy material, although if its weight is not suflicient to hold down the pieces effectively, it may be increased by placing on its upper surface a heavy block of concrete or other material, or augmented by' the application of a resilient force.

To assist in holding down the blocks as they pass bedeath the extreme forward end of hold down plate 36 and approach the cutter head 12, there is provided a plate extension 38 and a plurality of resilient fingers 39.

a The latter may be formed integrally with extension 33, preferably as flat leaf spring members. They are spaced apart to engage the blocks at various points and to exert a substantial pressure upon them.

Although fingers 39 assist materially in holding down the blocks as they approach the cutting area, their effectiveness is reduced to some extent by the fact that the blocks are of irregular dimensions. This causes plate 36 to rock and tilt during operation of the apparatus. These motions are imparted to fingers 39 which accordingly may not engage the blocks securely at all times. As a consequence, the blocks may buckle and jam so that flakes of uniform dimensions are not produced.

Hence there are provided auxiliary hold down means attached to a rigid frame member of the apparatus and operating on the surface of the blocks immediately adjacent the cutter head. In the illustrated embodiment, the auxiliary hold down means comprise a plurality of dogs 40.

Dogs 40 are mounted'for free rotation in vertical planes upon a horizontal shaft 42 which extends transversely of the apparatus and is journaled between vertical standards 44. The dogs are confined by means of collars 46 and are of sufiicient length to contact blocks 24 in the area between the ends of resilient fingers 39 and cutter head 12. To enable close approach to the cutter head in all vertical positions of the contact points of the dogs, the dogs and shaft 42 upon which they are mounted are positioned at as low an elevation as is possible while still maintaining clearance for passage of the blocks beneath them.

Adjustable resilient means are included in the assembly for pressing dogs 40 against the blocks with the pressure required to hold them securely. Such means may comprise a plurality of springs 48 interleaved between dogs 40. Springs 48 may be U-shaped in configuration. One end of each spring engages the adjacent dog and the other bears against a transverse adjustment rod 50. Accordingly keyed to a shaft 78 journaled within bearings fixed to the hold down plate 36.

To accommodate movement of plate 36, which moves vertically depending upon the thickness of the blocks passing beneath it, chains 70 are driven through a spur gear 84 fixed to the end of shaft 78. Gear 84 meshes with and is driven by spur gear 86 keyed to a shaft 88 which, in turn, is journaled in bearings attached to the frame of the apparatus. Shaft 78 then is maintained at a suitable working distance from shaft 88 with the teeth of gears 84, 86 in proper intermeshing relationship by means of the radius link members 90.

The upper and lower drive chains are driven synchronously with each other at the selected speed through a drive consisting of chain 92 interconnecting a sprocket 94- keyed to shaft 66 and a sprocket 96 keyed to shaft 88. Shaft 66 in turn is coupled to a variable speed motor as has been indicated above.

Operation The operation of the presently described apparatus is as follows:

First the knives 14 of cutter head 12 are adjusted to the desired depth. Then the scoring points 16 are spaced apart to the desired degree and the cutter head rotated at the selected constant speed by the motor. Wooden blocks, for example, planer ends cut to size to fit between the guide members 26, then are stacked in as many tiers as is expedient on the upper stretches of drive chains 60 which are supported by tracks 30. Rod 50 is set by means of lever 52 and pins 56 at a position in which springs 48 exert the desired amount of tension on dogs 40.

the springs exert downwardly upon the dogs a resilient 7 (force which may be varied by adjusting the position of rod 50.

Rod 50 is attached to a pair of levers 52 which may be mounted for free rotation on shaft 42. For convenience of adjustment, levers 52 are placed outside of and adjacent standards 44 which accordingly are formed with arcuate slots 53 having shaft 42 as their center.

A plurality of spaced openings 54 are also present in the standards, the openings being arranged in arcs which are concentric with slot 53. Pins 56 then may be placed through handles 52 and in selected corresponding ones of openings 54. This places rod 50 at a station at which springs 48 exert the desired force upon dogs 40. In this manner there is provided means for exerting a controlled but adjustable hold down pressure on the areas of the blocks closely adjacent the cutter head.

Drive means are provided for driving the blocks at a predetermined and uniform speed in the direction of the cutter head. The drive means illustrated comprises lower and upper assemblies engaging respectively the lower and upper surfaces of the blocks. The lower assembly comprises a pair of spaced apart, spurred chains 60 stationed within and parallel to guide members 26.

Chains 60 engage the forward drive sprockets 64 which are keyed to a drive shaft 66 which in turn is coupled to a variable speed motor, not illustrated. The chains also engage a pair of rearward idling sprockets rotatably mounted at the infeed end of the assembly. The upper or working stretches of the chains ride on and are supported by tracks 30.

The upper drive assembly comprises a pair of spaced apart endless drive chains 70 placed above and parallel to the lower drive chains 66. Like the lower chains, the upper chains are provided with outwardly extending spurs 72 adapted to engage the surfaces of the blocks. Chains 70 are mounted on forward drive sprockets 76 and rearward idler sprockets, not illustrated. Sprockets 76 are The variable speed feed drive motor then is set at the desired operating rate. It drives shaft 66 carrying sprockets 64, which drive the lower feed chains 60. It also drives shaft 88 through chain 92. This drives the upper drive chain 70, through a linkage including meshing spur gears 84, 86, shaft 78, and sprockets 76. Accordingly, chains 60, 70 are driven synchronously with their working stretches in contact respectively with the lower and upper surfaces of blocks 24 urging them in the direction of the cutter head.

Proper working relationship between shafts 78 and 88 is maintained despite irregularities in block dimensions by means of the radius link members 90. Also, the particular block being reduced by cutter head 12 is maintained securely against bed plate 34 by means of resilient fingers 39 cooperating with dogs 40. An effective restraint of the blocks, preventing their buckling and jamming, thus is maintained up to the cutting arc of the cutter head and is continued as the trailing ends of the block are engaged by the knives.

As a result the block is held securely and the knives of the cutter head shave from it crosscut flakes uniformly of the desired dimensions with a minimum formation of sticks and slivers. Furthermore the grain and the dimensions of the cut flakes are widely variable to suit a particular application or a particular type of wood block, regardless of its species or moisture content. These important advantages are obtained, furthermore, by means of apparatus which is simple in design, safe in operation, and characterized by a high production rate.

It is to be understood that the form of my invention, herewith shown and described, is to be taken as a preferred example of the same, and that various changes in the shape, size and arrangement of parts may be resorted to, without departing from the spirit of my invention, or the scope of the subjoined claims.

Having thus described my invention, I claim:

1. Wood reduction apparatus comprising cutting means for reducing wood pieces, a bed plate stationed adjacent the cutting means for supporting thewood pieces as they are cut thereby, guide means positioned for guiding the Wood pieces across the bed plate and against the cutting means, lower and upper driving means contacting respectively the lower and upper surfaces of the wood pieces, motor means connected to the lower and upper driving means for driving the working surfaces of the same in the direction of the cutting means, a floating hold down assembly adapted to rest on the upper surfaces of the wood pieces as they advance toward the cutting means, first WOOd hold down means on the outfeed end of the floating hold down assembly and positioned for pressure contact with the upper surfaces of the wood pieces, second wood hold down means connected to a stationary frame member of the apparatus and positioned for pressure contact with the upper surfaces of the wood pieces immediately adjacent the cutting means, the first and second hold down means coacting to hold the wood pieces against the bed plate as they are reduced by the cutting means.

2. The wood reduction apparatus of claim 1 wherein the second hold down means comprises a plurality of laterally spaced dogs and resilient means bearing against the dogs for pressing them resiliently against the surface of the wood.

3. The wood reduction apparatus of claim 2 wherein the dogs are mounted for angular movement on a horizontal shaft extending transversely of the apparatus and wherein the resilient means comprises a plurality of springs associated one with each of the dogs, each spring comprising a reversely bent piece of resilient metal one end of which engages the dog, the central portion of which is looped around the shaft, and the other end of which bears against a rod extending transversely of the apparatus substantially parallel to the shaft and spaced therefrom, lever means connected to the rod for moving the same between a plurality of positions on an arc of which the shaft is the center, and locking means for locking the rod in a selected position at which a desired tension is placed on the springs.

4. Wood defibering apparatus comprising a main frame, power driven cutting means mounted on the main frame for reducing wood pieces to fibrous form, a bed plate on the main frame stationed adjacent the cutting means for supporting the wood pieces as they are cut, flower drive chain means mounted on the main frame and having its upper stretch arranged firmly to support and deliver the wood pieces to the bed plate, a floating hold down assembly including a freely floating hold down frame, upper drive chain means mounted on the hold down frame parallel to the lower drive chain means and having its lower stretch arranged firmly to engage the upper surfaces of the wood pieces, resilient finger means mounted on the hold down frame and projecting therefrom above the bed plate for substantial pressure contact with the upper surfaces of the wood pieces supported on the bed plate adjacent the cutting means, a plurality of laterally spaced hold down members mounted on the main frame, above the bed plate and projecting resiliently downward toward the cutting means, the hold down members terminating between the resilient finger means and the cutting means for substantial pressure contact with the upper surfaces of the wood pieces in close proximity to the edge of the wood pieces being acted upon by the cutting means, first drive means mounted on the main frame and connected to the lower drive chain means, second drive means mounted on the hold down frame and connected to the upper drive chain means, radius link means pivotally interconnecting the first and second drive means for maintaining them a fixed distance apart whiile permitting the second drive means to rotate about the axis of the first drive means, thereby permitting the floating hold down assembly freely to move vertically to accommodate Wood pieces of diverse thicknesses between the working stretches of the upper and lower drive chain means, means interconnecting the first and second drive means for simultaneous rotation, and motor means connected to one of the drive means for driving synchronously the upper and lower drive chain means.

References Cited in the file of this patent UNITED STATES PATENTS 689,027 Schleicher Dec. 17, 1901 707,116 Johnson Aug. 19, 1902 1,678,835 Vivarttas July 31, 1928 2,756,788 Fish July 31, 1956

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