Wood defibering apparatus

Oct. 29, 1957

2,811,183

A. L. MOTTET

WOOD DEFIBERING APPARATUS

Filed June 15, 1953

Sheets-Sheet 1

<img file="US2811183A_D0001.tif" />

2,811,183

A. L. MOTTET

WOOD DEFIBERING APPARATUS

Oct. 29, 1957

Filed June 15, 1953

Sheets-Sheet 2

<img file="US2811183A_D0002.tif" />

Oct. 29, 1957

2,811,183

A. L. MOTTET

WOOD DEFIBERING APPARATUS

Filed June 15, 1953

Sheets-Sheet 3

<img file="US2811183A_D0003.tif" />

<img file="US2811183A_D0004.tif" />

United States Patent Office , .. _o

Patented Oct. 29, 1957

2,811,183

WOOD DEFIBERING APPARATUS

Arthur L. Mottet, Longview, Wash., assignor, by mesne assignments, to International Paper Company, New York, N. Y., a corporation of New York

Application June 15, 1953, Serial No. 361,480

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.

In one important method of making hardboard, wood is reduced to the form of crosscut fibrous elements or flakes by cutting it, with 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 difficult to do in commercial defibrators because of the high degree of vibration necessarily present; because of the difficulty 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 defibering 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 defibering apparatus which has a high production rate although the apparatus itself is relatively small in size and inexpensive to construct. - --— 2

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

Another object of the present invention is the provision of wood defibering 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:

Figure 1 is a plan view of the presently described wood 15 defibering apparatus;

Figure 2 is a view in side elevation of the apparatus illustrated in Figure 1, the planes of rotation of the cutter head surface and the cutting knives being shown by dotand-dash lines;

²⁰ Figure 3 is a plan view of alternate wood hold-down means for use in the apparatus of Figures 1 and 2;

Figure 4 is a side elevational view, partly in section, taken along the line 4—4 of Figure 3; and

Figure 5 is an enlarged fragmentary view in side ele²⁵ vation of the cutting area of the apparatus, showing the relationship between the cutter head, cutting knife and wood block, the positions of the cutting knife and block just preceding the cutting operation being shown by dotted lines.

As is illustrated in the drawings the presently described : wood defibering apparatus is provided with cutting means' mounted on the frame 10 of the apparatus. Although the' cutting means may comprise any suitable type of reciproeating or rotary cutter, it preferably .comprises a rotary cutter head of the type indicated generally at12. 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 ⁴⁰ desired to determine the length of the fibrous, elements cut from the wood by tthc cutter head. A hopper 17 or other receiving means is placed below the cutter head for receiving the cut flakes and conveying them away ₄₅ from the apparatus.

The cutter head is rotatably mounted on a shaft 18, journalled in bearings 20. It is driven at the selected rotational speed by means of motor 22.

The blocks of wood 24 which are fed to the cutter 50 ^bead 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 55 length. These pieces are fed into a bed, the width of which is determined by a pair of elongated guide strips 26, directed toward the cutter head and provided with outwardly flared sections at their outer ends.

On the bottom of the feeding bed are a pair of spaced ₆₀ 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 over which the wood pieces pass as they are reduced to fibrous form.

₆- 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 plate 36 dimensioned to overlie the Wood blocks contained Im 70 the apparatus. It preferably is made of a heavy material, although if its weight is not sufficient to hold down the pieces, effectively, it may be. increased by placing on its

183 , shaft of a variable speed drive 100 operated by a motor 102.

As stated hereinbefore, the blocks 24 are moved toward the cutter knives 14 positively and at a uniform but adjustable rate of speed which is determined by selective adjustment of the variable speed drive 100 of motor 102. As indicated in Figure 2 of the drawings, and best illustrated in Figure 5, the speed of forward movement of the block toward the cutter head 12 is such, with respect to the rotational speed of the cutter head, that each successive scoring and cut is made before the block has moved into abutment with the surface of the cutter head. This is indicated in Figure 5 by the dotted line positions of the block 24 and knife 14. Thus, the depth of the scoring and cut is determined by the relative speed of the cutter head motor 22 and the motor drive 100 of the drive chain motor 102, it being necessary only to adjust the projection of the cutter knives 14 and scoring points 16 from the surface of the cutter head 12 a distance greater than the desired thickness of cut. In this manner a space is maintained between the forward surface of the block being cut and the surface of the cutter head. This manner of operation achieves the objectives mentioned hereinbefore, namely it provides maximum precision of control for the production of high quality flakes of predetermined but variable thickness; it reduces to a minimum the production of sticks and slivers by eliminating frictional contact between the block and cutter head; and it provides such production with a minimum of power by eliminating power waste which otherwise results from the friction of the block against the surface of the cutter head.

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 speed by motor 22. Wooden blocks, for ex40 ample 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.

The variable speed drive 100 then is set at the desired 45 operating rate. It drives chain 98, which in turn rotates shaft 68 carrying sprockets 64, which drive the lower feed chains 60. Sprocket 94 on shaft 68 drives sprocket 96 on shaft 88.

Shaft 88 mounted on the frame of the apparatus carries 50 spur gears 86 which engage spur gears 84 keyed to shaft 80. Shaft 88 mounted on the frame of the apparatus and shaft 80 mounted on the floating hold down plate 36 are maintained in proper working relationship to each other by means of the link members 90. Sprockets 76 55 keyed to shaft 80 engage and drive the upper feed chain 72. Accordingly, chains 60 and 72 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. The GO particular block being reduced to fibrous form by the cutter head is maintained securely against bed plate 34 by means of the hold down springs 40.

As a result the block is held securely and the knives of the cutter head shave from it crosscut flakes uniformly of 65 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 ad70 vantages 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 pre75 ferred example of the same, and that various changes in the

- 2,811, upper surface a heavy block 38 of concrete or other material.

The holding function of the hold down plate is augmented by attaching to its outfeed end resilient means for engaging the upper surfaces of the wood blocks and for 5 holding them firmly against bed plate 34 during the Cutting Operation until the trailing portion of these blocks'has been substantially entirely reduced to fibrous elements. Iri the form illustrated in Figures 1 arid 2, the resilient hold down means may comprise a plurality of leaf springs 40 10 attached to the end of hold down plate 36 and directed downwardly into engagement with the wood blocks. The springs are spaced apart longitudinally of the apparatus so that they contact each block in several places, assuring that it will be held securely. 15

In the form illustrated in Figures 3 and 4, the resilient means for holding down the wood blocks as they are reduced by the cutting means comprise a plurality of dogs 42 of varying lengths and having pointed ends which engage the upper surfaces of the wood blocks. The dogs 20 are pivotally attached to a common shaft 44 mounted on arms 46, which in turn are attached to the frame member 50.

The dogs are arranged in groups as indicated in the drawing to engage each block of wood at a number of spaced 25 apart points. Each dog within a given group is separated from the other members of the group by means of a spacer 52, and the groups are maintained separate from each other by means of collars 54.

Resilient means are provided for maintaining the dogs 30 resiliently in contact with the wood blocks. These may comprise comb-shaped leaf spring assemblies 56, each of which is bolted to the frame member 50, and provided with a plurality of unit leaf springs 58, which are spaced apart from each other and which resiliently engage the dogs 42 in the manner illustrated in Figure 4.

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 endless chains 60 provided with spaced apart spurs 62 and stationed within and parallel to guide members 26. The chains engage forward sprockets 64 and rearward sprockets 66 rotatably mounted, respectively, on shafts 68, 70, The upper or working stretches of the chains ride on and are supported by tracks 30, and accordingly are reinforced for supporting blocks 24 resting thereon.

The upper drive assembly comprises a pair of spaced apart, endless drive chains 72 placed above and parallel to the lower drive chains 60. Like the lower chains, the upper chains are provided with outwardly extending spurs 74 adapted to engage the surfaces of the blocks. Chains 72 are mounted on forward sprockets 76 and rearward sprockets 78 rotatably mounted respectively on the rotatable shafts 80, 82. These shafts are journalled, respectively, within bearings fixed to the forward and rearward portions, respectively, of hold down plate 36.

The upper drive chains 72, mounted on the floating hold down plate, which moves vertically depending upon the thickness of the blocks passing beneath it, are driven through a pair of spur gears 84 fixed to the ends of shaft 80, Gears 84 mesh with and are driven by spur gears 86 keyed to a shaft 88 which is journalled in bearings attached to the frame of the apparatus. Shaft 80 is maintained a working distance away from shaft 88 with the teeth of gears 84 and 86 in proper meshing relationship with each other by means of the link members 90.

The upper and lower drive chains are driven synchronously with each other at the proper speed through a drive consisting of chain 92 interconnecting a sprocket 94, keyed to shaft 68 and a sprocket 96 keyed to shaft 88. Shaft 68 in turn is driven through a chain 98 connected to the

2,811,183 shape, size and arrangement of parts may he resorted to, without departing from the spirit of my invention, or the scope of the subjoined claims.