Title:
Sawdust recovery process and apparatus
United States Patent 2342321


Abstract:
My separating mechanism herein disclosed is particularly useful in removing wood chips and fibers which result from a sawing operation, for example, from water. A typical installation is one in which buoyant logs are cut by a chain saw so that the particles of wood severed in sawing float in...



Inventors:
Adams, Chester M.
Application Number:
US37347541A
Publication Date:
02/22/1944
Filing Date:
01/07/1941
Assignee:
US PLYWOOD CORP
Primary Class:
Other Classes:
210/161, 210/403
International Classes:
B23Q11/00
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Description:

My separating mechanism herein disclosed is particularly useful in removing wood chips and fibers which result from a sawing operation, for example, from water. A typical installation is one in which buoyant logs are cut by a chain saw so that the particles of wood severed in sawing float in the water. It has been found that if these chips are not removed they soon become waterlogged and sink to the bottom, thus filling up the log channels. Those which do not sink there may be carried by the current onto other property where they become a nuisance, and may render the person responsible for the sawing liable to damages for such water contamination. Elimination of such material is very important where between 500 and 700 cuts are made daily through logs averaging 40 inches in diameter and the width of cut is 7/e of an inch, as in the mill where my device is installed.

The purpose of my device, therefore, is to remove floating debris, which is in a relatively finely comminuted state, from liquid, and to deliver such material for burning, or other disposal, practically free from unabsorbed liquid.

The mechanism in general may consist of a power-driven water wheel having generally radial vanes, which is rotated in a direction to create a current toward it of water in which the debris is floating, and the debris and water intermingled will be picked up by the wheel. The wheel's rotating vanes have a scooping action, so that they elevate the water and refuse mixture a distance substantially equal to the radius of the wheel during a quarter revolution. At this point the vanes successively dump such mixture into a chute, which empties into one end of a tubular, generally horizontal, strainer. Such strainer is inclined slightly downward from the chute, and is rotated about its axis by suitable drive mechanism. It may conveniently be made of wire screen. As the screen revolves the debris clings to its upward moving side. When it has been carried upward so far that it can not remain longer on the screen side it tumbles back down toward the bottom, and is again carried up, affording a continuous mixing and agitating operation. The bottom portion of the screen is thus sparsely covered with refuse so that water from the mixture can drain through it, and the progressive tumbling action of the debris moves it in a generally spiral path toward the lower end of the screen. Freed from water, it is here discharged into any suitable collecting mechanism.

This may be in the form of a bucket conveyor, which delivers the chips and fibers to a furnace, storage bin, or other processing apparatus.

It will be seen that such mechanism is efficient in that substantially all the refuse is recovered and sucn material is separated quickly from the water. The operation of the mechanism does not tend to dissipate the material as it is picked up, but on the contrary a positive collecting action is created. Moreover, the sepi0 arating action is tnorough so that only water actually absorned by the wood is not removed, and such aosorbed water will be slight, for the wood in chip and nber form, being recovered immediately after the cutting operation, does not have an opportunity to aosorb an appreciaole amount of water. Mioreover, the mechanism is automatic in operation in that, once the driving motors have been started, the separating action is carried out without attention on the part of the sawyer during the cutting operation.

The capacity of the mechanism shown in the drawing will depend not only on its size, but also to a large extent upon the speed at which it is operated. This can, of course, be varied within limits, and different speeds, as well as detail modifications, may be necessary for different installations.

Figure 1 is a side elevation view showing the complete assembly of my separating mechanism, while Figure 2 is a horizontal section through the water wheel or pick-up mechanism, taken along line 2-2 of Figure 1, and Figure 3 is a vertical section of the separator or strainer mechanism along line 3-3 of Figure 1.

As pointed out above, when the refuse from a drag sawing or chain sawing operation, composed of small chips and wood fibers, is not removed from the water, it shortly becomes waterlogged, and either fills up the log channel or is deposited on adjacent land or bed. The mechanism illustrated is particularly adapted for removing such refuse material from the water before it becomes heavy enough to sink, and is most effective when used in conjunction with a chain sawing operation. In the typical installation shown in Figure 1 the chain saw S cutting the log L is driven by suitable motor and pulley mechanism D in the direction of the arrows, so that, as shown, the chips are all discharged on 60 one side of the log, according to the direction of movement of the lower run of the saw. This debris is thus given an initial impetus toward the separating mechanism, which is located on the chip-discharge side of the log.

In addition, the water wheel I is rotated by a suitable motor and gear reduction mechanism 10 in the direction indicated by the arrow, so that the vanes ! I create a curent of water and refuse into and through the flume 12 from the saw S, along the course shown. The mouth of this flume should be flared laterally if the current in the body of water is such that it would tend to sweep the debris beyond it before the current created by the saw and the water wheel is able to draw the refuse into such flume, or if for other 1 reasons it tends to escape. It is not necessary that the lower edge of the flume be submerged very deeply below the surface because the water flowing into it and returning from the screen creates an upcurrent.

While the vanes II of the water wheel I are disposed generally radially, they preferably are not precisely so, but the circumferential ends should trail the central ends somewhat in the direction of rotation of the wheel. This disposition, as shown in Figure 1, affords an inclination to the vanes so that the water and debris mixture will flow from them when they have been elevated 'into a position at approximately the level of the wheel axis or supporting shaft, and slightly above the portion 13 of casing 14 which conforms generally to the periphery of the wheel. At the upper edge of this curved ,casing portion a discharge chute 15 is connected, which leads into the separating strainer 2. The inner or central end 17 of each vane I 1 is preferably curved in advance of the plane portion in the direction of wheel rotation, so that a surge of water and debris onto the vanes will not overrun their inner ends, to be dropped into the center of the wheel.

The water and chip mixture will be deposited from chute 15 well within the tubular strainer 2, because of the inward projection of such chute, as shown in Figure 1. Such strainer is preferably cylindrical in shape and made of wire mesh screen, although any suitably perforated material could be used. The axis of this screen is inclined downward from such feed end to its discharge end to a greater or less degree, depending upon the speed at which it is desired that the chips progress along it. Various factors will determine the separating capacity of the screen, including its diameter, the speed of its rotation, and the inclination of its axis, for the larger such screen the greater will be the area provided for distribution of the refuse material, and the faster the screen rotates and the greater slope it has the more quickly will such refuse move lengthwise through the screen. Naturally the shorter the screen the more quickly will the separated solid matter be discharged from its lower end.

The screen cylinder 2 is rotatably cradled at each end on rollers 20 supported in any suitable manner, which run in tracks 2S secured to its periphery. Obviously the amount of longitudinal inclination may be varied to a limited extent by raising or lowering appropriately one or both sets of rollers, provided that such adjustment is not sufficient to interfere either with the feeding action of chute 15 or the removal action of the refuse receiving mechanism at the discharge end of the tube. It is immaterial in which direction the screen 2 is revolved, but the effect of such rotation, in the direction indicated by the arrow, is illustrated in Figure 3. A motor 22 may be provided to rotate the screen, such as by means of a belt 23 received in a channel 24 encircling the cylindrical screen and secured to it. It will be evident that such driving mechanism is merely illustrative, and that a gear drive or a friction wheel drive or other suitable mechanism might be substituted for that shown.

Collecting apparatus is provided to receive the chips from the screen, which may be a bucket conveyor B, to elevate the separated solid material and to dump it into a refuse conveyor C. The problem solved by my invention is the separation of the debris from unabsorbed water, and it is immaterial what disposition is made of it after the water has been removed.

As the teeth of saw S drag the chips and fibers out of the cut the current created by movement of the saw, as well as by rotation of vanes 11, draws into flume 12 the water on which this debris floats. As the vanes II dip into the water they scoop up the water carrying this refuse and elevate the mixture to chute 15. During this movement the shield 13 prevents the mixture spilling off the vanes, although it may be unnecessary if the rotation of the wheel is fast enough to provide sufficient scooping action. By the time the vanes have reached the position of chute 15 the inward rush created by the scooping action has subsided, and in conjunction with the centrifugal force the opposite tendency controls, so that the fluid mixture moves outward and downward along the vanes into the chute. As soon as the mixture moves down chute 5I into strainer 2 the water from the mixture begins to drain through the bottom of the screen while its rotation carries upward solid material with the undrained part of the water, as shown in Figure 3. As the mass reaches a point usually below the center of the screen it progressively rolls and falls back down toward the screen bottom. This action agitates the mass and tends to free the chips from the water, so that the latter may pass out through the screen. Such upward movement of increments of the mass is in a precisely circumferential path, having an absolute horizontal component because of the slope of the screen's axis, whereas when these increments drop back toward the bottom of the screen their movement is substantially in a transverse, perpendicular plane, so that the material then progresses lengthwise of the screen by the amount of such horizontal component. Such increments of the mass therefore traverse a generally spiral path along the screen, first laterally upward and forward and then downward and laterally in the opposite direction, to its discharge end. The tumbling which the mass has undergone during this movement is sufficient to separate the free water from the body of chips, so that while they will not be dry when discharged from the screen 2, the mass will be practically free of unabsorbed water. The solid material thus separated may be subjected to any subsequent treatment desired.

What I claim as my invention is: 1. A method whereby sawdust which is formed by sawing a log or the like floating on an open body of water is collected, comprising establishing a current in the open body of water at the water surface in the vicinity of the sawing, and away therefrom, thereafter confining the surface water so moving, and the sawdust floating thereon, within a channel, scooping up a fluid mixture of sawdust and water carried from the open body of water into the channel and confined therein, elevating such mixture well above the surface of the water, and thereafter draining the water from the sawdust.

2. Mechanism for recovering floating sawdust from water, comprising a water wheel having an unobstructed periphery and generally radiating, imperforate vanes, means supporting said water wheel with only the lower, minor portion of its periphery submerged beneath the surface of the water, drive means to rotate said water wheel in a direction to create by said vanes a current at the water surface from a floating log being sawed toward the water wheel, a casing closely embracing the sides and lower peripheral portion of said water wheel, and an open topped flume having its bottom disposed slightly below the surface of the water and extending from said casing toward the log being sawed, operable to confine and guide floating sawdust moved by such current from the log to said water wheel, said water wheel vanes, by rotation of the water wheel, being operable to scoop up the sawdust floating through said flume.

3. Mechanism for recovering floating sawdust from water, comprising a rotative water wheel having a plurality of imperforate vanes fixedly mounted generally radially but with their central ends in advance of their peripheral ends in the direction of rotation of said water wheel, means supporting said water wheel with its bottom segment submerged in the water on which the sawdust floats, means for rotating said water wheel to pass the lower portion of its periphery through the floating sawdust, thereby to pick up with said vanes a fluid mixture of sawdust and water, means to receive such mixture from the peripheral edges of said vanes well above the surface of the water but while said vanes are still inclined downwardly and outwardly, and means for separating the sawdust from the water picked up.

4. The mechanism of claim 3, and a casing closely embracing the periphery of the water 4 wheel and extending from side to side thereof over approximately one quarter of its circumference, such quarter being always that emerging from the water, and extending from below the surface of the water forwardly and upwardly 4 in the direction of the wheel's rotation.

5. Mechanism for recovering floating sawdust from water, comprising a rotative water wheel including a plurality of imperforate vanes having planar portions fixedly mounted generally radially but with the central ends of such portions being in advance of their peripheral ends in the direction of rotation of said water wheel, and a lip curving from the inner end of each planar vane portion forwardly in the direction 5 of rotation of said water wheel, means supporting said water wheel with only the lower, minor portion of its periphery submerged beneath the surface of the water, means for rotating said water wheel to pass its periphery through the 6 floating sawdust, thereby to pick up with said vanes a fluid mixture of sawdust and water, means to receive such mixture from the peripheral edges of said vanes well above the surface of the water but while said vanes are still in- 6 dined downwardly and outwardly, and means for separating the sawdust from the water picked up.

6. Mechanism for recovering floatable, comminuted, solid material from liquid, comprising an imperforate scoop, means operable to move said scoop in a generally upright position to pass its lower end only through the liquid and the floating solid material, and thereafter to lift said scoop from the liquid, with a fluid mixture of such floatable material and liquid thereon, into a downwardly and outwardly inclined position elevated above the surface of the liquid, and means adjacent to said scoop during its movement from the surface of the liquid upward to such elevated position for retaining the fluid mixture of floatable solid material and liquid on said scoop.

7. Mechanism for recovering floating sawdust from water, comprising a rotative water wheel having generally radiating, imperforate vanes, means to rotate said water wheel with the lower portion only of its periphery submerged beneath the surface of the water on which the sawdust floats, thereby moving said vanes in a generally upright position through the water and floating sawdust to scoop up a fluid mixture of sawdust and water, and then lifting said vanes, with such sawdust and water fluid mixture thereon, into a downwardly and outwardly inclined position elevated above the surface of the water, and an imperforate shield generally conforming to the curvature of the water wheel's periphery, disposed adjacent thereto above the surface of the water in the direction of its rotation, for retaining the fluid mixture of sawdust and water Son said vanes during their movement from the Swater surface upward to such elevated position.

8. Mechanism for recovering floating sawdust from water, comprising a rotative water wheel having a plurality of imperforate vanes fixedly 0 mounted generally radially, but with their central ends in advance of their peripheral ends in the direction of rotation of said water wheel, means for rotating said water wheel to pass its periphery through the floating sawdust, in a 5 direction to create a current from a floating log being sawed toward the water wheel, a casing closely embracing the sides and lower peripheral portion of said water wheel, a flume extending from said casing toward the log being sawed, opo0 erable to confine and guide sawdust moved by such current from the log to said water wheel, said water wheel vanes, by rotation of the water wheel, being operable to scoop up a fluid mixture of sawdust and water moving through said 5 flume, a generally cylindrical screen having its feed end adjacent the upwardly moving edge of the water wheel and its discharge end remote therefrom, for separating the sawdust from the water, means supporting said screen with its axis 0 inclined slightly downward from its feed end to its discharge end, means for rotating said cylindrical screen about its axis to tumble the sawdust and water mixture and thereby effect such separation, and a chute receiving the fluid mixture 5 of sawdust and water from said water wheel vanes in elevated position, and discharging such mixture within the feed end of said screen.

CHESTER M. ADAMS.