US 3621997 A
Description (OCR text may contain errors)
Inventor Oliver 1K. Hobbs Box 1306, Suffolk, Va. 23434 Appl. No. 882,857
Filed Bees, 1969 Patented Nov. 23, 197] SEPARATOR 6 Claims, 4 Drawing Figs.
lU.S. Cl. 209/12, 209/76, 209/1 14, 209/307 Int. Cl. B071) 1/10 Emails"... 209/307,
308, 261467, i9filllif1 15, 1 l6, 12
References Cited UNITED STATES PATENTS Primary Examiner- Frank W. Lutter Assistant E.raminerWilliam Cuchlinski, Jr. Arrorney-Clelle W. Upchurch Lien Lien
ABSTRACT: A device for separating bark useful for mulching around plants from undesirable materials mixed therewith such as wood chips, sticks, sawdust and slivers of the cambium layer of a log has an endless conveyor composed essentially of a series of perforated sheet metal sections rigidly secured only at their leading edges to horizontally spaced sprocket chains. The sprocket chains are diverted by idler wheels from a normal elliptical path to provide a conveyor surface having a portion thereof which is substantially vertical and to cause hinging of the sections of the conveyor to improve separation of This invention relates generally to a device for separating materials of different configuration, one or more from the others, and more particularly to such a device particularly advantageous for separating bark suitable for mulching plants from unsuitable materials ordinarily mixed therewith when a log is debarked.
The use of bark as a mulch around trees, shrubs and various other plants is becoming more and more prevalent. Tree bark is very well suited for such use but other materials such as slivers of the cambium layer of a log which are frequently mixed with bark when a log is debarked detract from the usefulness of the bark. For this reason, it is desirable to separate any cambium, wood chips, sticks and the like from the bark before it is used as a mulch.
It is therefore an object of this invention to provide a device which will efficiently separate bark from the undesirable materials mixed therewith after logs are debarked by equipment available in the conventional sawmill. Another object of the invention is to provide a novel device for separating desirable bark nuggets from wood slivers, sticks and the like. Still another object of the invention is to provide a novel endless conveyor for use in bark-recovery apparatus.
Still other objects will become apparent from the following description of the invention with reference to the accompanying drawing in which FIG. 1 is a side elevation of one embodiment of the invention shown at an operative angle;
FIG. 2 is a longitudinal section of the embodiment of FIG. 1;
FIG. 3 is a fragmentary horizontal sectional view through the embodiment of FIG. 2 taken .along the line 3-3 of FIG. 2; and
FIG. 4 is an enlarged fragmentary vertical section taken along the line 4-4 of FIG. 2;
The objects of this invention are accomplished, generally speaking, by providing a continuous conveyor composed essentially of a series of perforated plates having their ends secured adjacent their leading edges to horizontally spaced upper and lower sprocket chains forming loops about longitudinally spaced sprocket wheels with the upper portions of the loops lying against a plurality of idler wheels which direct the chains as they rotate downwardly below a normal elliptical path to form a pocketlike depression in the upper portion of the conveyor loop. The sprocket chains are moved in a direction from the lower sprocket wheels towards the upper sprocket wheels. Each perforated platelike section of the conveyor has a plurality of horizontally spaced sheet metal fins having a sloping, serrated or notched upper edge. These fins have their lower edge or base welded or otherwise rigidly secured to the upper surface of the perforated plate. They are mounted on the plate with their greatest height adjacent the trailing edge of the plate or section. Most of the fins are not mounted parallel with the ends of the plates but, on the contrary, are mounted at an angle thereto with their leading end nearer than their trailing end to the closest end of the plate. In other words, most of those fins on a platelike section on one side of the middle line thereof will have their leading edges nearer than their trailing edges to one end of the section while those on the opposite side of the middle line will have their leading edges nearer than their trailing edges to the opposite end of the platelike section. The perforations in the plates and the serrations in the upper edges of the fins are large enough to catch the ends of sticks and wood slivers normally mixed with bark.
Bark most suitable for surface-mulching purposes will readily flow downwardly over a surface sloping at an angle of from about 40 to 50 above horizontal while woody materials such as the cambium layer of a log will not flow or slide easily unless the surface is at an angle of 70 to 90. It is therefore preferred that the portion of the conveyor nearest the discharge end of the device have a slope of less than 70 and most preferably from about 40 to about 50. Preferably, the sprocket chains are rotated at a speed of about 100 feet per minute.
A preferred embodiment of the invention is illustrated in a side elevation at its best operating angle in FIG. 1. Sprocket wheels 7, 7a, 14 and 14a are driven by an electric motor 34 through suitable belts and drive wheels. The housing of the apparatus is supported by any suitable metal framework including legs and crossbars and may include steps and a platform to provide access to a hopper or the like above opening 21. A longitudinal section through the separator is shown in FIG. 2 but for convenience this view does not indicate the operating angle since this is adequately taken care of in FIG. 1.
. Referring now to FIGS. 2 and 3 of the drawing, sheet metal top panel 2, bottom panels 5 and 6, end panels 3 and 4 and side panels 32 and 33 combine to form a housing enclosing a continuous conveyor 1. Horizontally spaced sprocket wheels 7 and 7a are mounted on shaft 25 which is joumaled at its ends in side panels 32 and 33. Shaft 26 joumaled in side panels 32 and 33 bears sprocket wheels 14 and 14a spaced longitudinally from the sprocket wheels 7 and 7a. Sprocket chains 24 and 24a are horizontally spaced from each other and form a generally looped shape path about sprocket wheels 7 and 14 and 7a and 14a, respectively. Sprocket chains 24 and 24a are driven in a clockwise direction by the sprocket wheels as indicated by the arrows in FIG. 1.
Conveyor 1 is composed of a plurality of plates 16, each welded or otherwise rigidly secured to brackets 29 and 29a not shown at opposite ends thereof. Ears 23 and 280 on links in sprocket chains 24 and 241a, lie over the upper horizontal surface of brackets 28 and 23a and are bolted thereto to rigidly fasten conveyor 1 to the sprocket chains as best shown in FIG. 4.
Sprocket chains24 and 24a are supported against sagging intermediate sprocket wheels 7 and 14 and 7a and Ma from below by idler wheels 8, 9 and 10, each joumaled in side panel 32 and by idler wheels 8a, 9a and 10a, each joumaled in side panel 33.
Idler wheels 11, 12, and 13 are joumaled in side panel 32 and rotate against the top of chain 24 forcing it to follow a path which extends downwardly from a normal elliptical path.
Corresponding idler wheels 11a, 12a and 13a are joumaled in sideplate 33 and rotate against the top of sprocket chain- 24a forcing it to follow a path corresponding to that of chain 24. The bed of conveyor 1 formed by platelike sections 16 adjacent idler wheels 8, 9, 10, 11, I2 and 13 is thus depressed or in the general shape of a pocket adapted to receive material to be separated. Idler wheels 15 and 15a which are spaced below sprocket wheels 7 and 7a are used to adjust the tension on chains 24 and 24a.
Sheet metal plates 16 are provided with perforations 30 and terminate at the ends thereof in vertical end panels 17. Each plate 16 has transversely spaced fins or hooks 18 welded or otherwise secured thereto. Fins 18 extend substantially across the width of plates 16 and have a serrated or notched upper edge 31. Only the leading edges of plates 16 are secured to chains 24 and 24a with the trailing edge being unsecured and overlapping the leading edge of the adjacent trailing plate 16. As shown in FIG. 3, those fins 18 adjacent each edge of a plate have their leading ends nearer than their trailing ends to that edge. Preferably each plate 16 has one fine 18 which is substantially parallel to an end edge of the plate 16. The parallel fins 18 are on alternate opposite sides of the centerline of the conveyor 1, as shown in FIG. 3. In other words, one plate 16 will have a parallel fin 18 on one side of the centerline while the plate 16 immediately in front of and the plate 16 immediately behind will have a parallel fin 18 on the opposite side of the centerline. It is preferred that the serations in the upper edge of fins 18 have a rounded bottom so that strips of material trapped therein can fall out easily when the plates 16 are inverted as they pass through the lower portion of the loop shaped path.
An opening 21 is provided in top panel 2 through which material to be separated is poured or otherwise spread on the surface of conveyor 1 in the pocket formed adjacent idlers 8, 9, 10, ll, 12 and 13. Side shields 19 and 19a are fastened with screws or by other means at their top to side panels 32 and 33 35 and overlap the edges of conveyor 1 fitting inside end panels 17 of plates 16 and extending upwardly to just below top panel 2. Shields 19 and 19a terminate near the end of conveyor 1 adjacent sprocket wheels 7 and 7a and just in front of sprocket wheels 14 and 14a. Splash plates or deflectors 27 and 27a are fastened to sidewalls 32 and 33 alongside sprocket wheels 14 and 14a to deflect material falling off conveyor 1 to a point back on the conveyor.
A relatively thin flexible curtain 20 of rubber, plastic, fabric or the like may be fastened along its upper edge to to panel 2 and extend across conveyor 1 just below opening 21. Curtain 20 terminates just above the surface of conveyor 1 and discourages flow of all material except the more fluid material downwardly over conveyor 1.
Spout 22 serves as an opening through which material passing over conveyor 1 is discharged, The material falling through perforations 30 or that carried over sprocket wheels 14 and 14a by conveyor 1 is discharged from below conveyor 1 through opening 23.
When a mixture of bark with wood splinters and chips is placed on the surface of conveyor 1 adjacent idlers 11 and 12, small particles will sift through perforations 30. Some stiff wood, splinters, sticks or slivers having an end smaller than perforations 30 will become caught therein. Hooks or fins 18 will catch long pieces of flexible material such as strips of the cambium layer of a log or other slender material. Bark chunks will roll under curtain 20 and OK the lower end of conveyor 1 through opening 22. The splinters and other material caught in perforations 30 and by fins 18 are carried up to the top of the conveyor loop and each plate 16 as it passes over sprocket wheel 14 will hinge and shake the material therefrom. Any material not firmly engaged in conveyor 1 which has been carried this far will be tossed up and will roll back down conveyor 1 into the bed of material adjacent idlers 11 and 12.
As the moving bed of conveyor 1 passes upwardly under idlers l1 and 12, it passes under a rolling, tumbling mass of material. As the bed or surface of conveyor 1 approaches the vertical plane, idlers 13 and 13a which roll on the side bars of chains 24 and 24a produce high frequency vibrations of low magnitude in plates 16. This vibration tends to shake loose material which is not firmly engaged by a plate 16. As chains 24 and 24a pass over wheels 14 and 14a, plates 16 pivot violently and shake loose the material caught in perforations 30 and trapped by fins l8. Spherical particles which had been held by the entrapped material will roll back down conveyor 1 After chains 24 and 24a pass beyond sprocket wheels 14 and 14a and start an approximately straight path, the overlying edges of plates 16 are snapped against each other and dislodge material clinging to conveyor 1. The weight of plates 16 tend to cause chain links to which they are attached to pivot and to keep the chain on the upward part of its path tight and thereby prevent conveyor 1 from sagging in the pocket section from weight of the material thereon.
Although the invention has been described in detail for the purposes of illustration, it is to be understood that such detail is solely for that purpose and that variations can be made by those skilled in the art without departing from the spirit and scope of the invention except as it may be limited by the claims.
1. A device for separating the components of a mixture of materials which comprises a continuous conveyor composed essentially of a series of perforated platelike sections each rigidly secured at opposite ends adjacent its leading edge to horizontally spaced sprocket chains and having an unsecured trailing edge which overlaps the leading edge of the next adjacent section, said sprocket chains forming loops about longitudinally spaced lower and upper sprocket wheels each of said loops having an upper portion above said sprocket wheels and a lower portion below said sprocket wheels, means adjacent said lower sprocket wheels for supporting said upper portions of said chains, means for diverting said chains downwardly from said support means to form a depression therein between said support means and said upper sprocket wheels and to form simultaneously a pocket in said conveyor, said conveyor being inclined above horizontal with the angle of inclination above the pocket being greater than that below the pocket and sufficient for unattached material to fall back into the pocket, means for introducing material to be separated into said pocket, separate means for discharging material from above and from below said conveyor, and means for driving said conveyor with its upper portion moving from said lower sprocket wheels towards the said upper sprocket wheels.
2. The device of claim 1 wherein said conveyor is enclosed within a housing having top, bottom, end and side panels and a pair of shields secured to opposite side panels overlap the edges of said conveyor to prevent accumulation of material along the edges of the conveyor.
3. The device of claim 1 wherein longitudinally extending fins having a serrated upper edge are mounted on each section with their leading ends nearer than their trailing ends to the closest end of said section.
4. The device of claim 3 wherein said supporting means comprises a plurality of idler wheels below said chains and said diverting means comprises a plurality of idler wheels above said chains.
5. The device of claim 1 wherein said sections tenninate in end panels, said conveyor is enclosed in a housing having top, bottom, end and side panels, and a shield secured to each of said side panels extends downwardly from adjacent said top and inside of said end panels of said sections to near the surface of said conveyor, said shield extending longitudinally from adjacent the lower end of said upper portion of the chains to adjacent the upper end of said depression.
6. The device of claim 1 wherein the angle of inclination of the conveyor between the lower sprocket wheel and the pocket is from about 40 to about 50 above horizontal and the angle of inclination of the conveyor between the pocket and the upper sprocket wheel is from about 70 to about