US 2119676 A
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June 7, 1938. R HELLER 2,119,676
Filed May 28, 1934 5 Shets-Sheetl Rz'chardD/iellef June 7, 1938.
R. D. HELLER Filed May 28, 1934 5 Sheets-Sheet 3 Patented June 7, 1938 r UNITED STATES PATENT OFFICE TROMMEL Richard D. Heller, Boise, Idaho Application May 28, 1934, Serial No."727,897
My invention relates to trommels, and is particularly designed for screening or classifying ore in dry placer mining operations, where water is not available.
Gold particles can be separated by an air jet orblast from base particles of about the same size, but not from larger particles, hence it is important, in such operations, to classify the materials accurately according to size, and this is my primary object.
It is an object of my invention to provide a trommel which will operate satisfactorily on such 1 materials to screen or classify them in the absence of water.
It is also an object to provide such a trommel which will be light, enabling it to be transported easily, and which can be quickly and easily set up, and which will operate satisfactorily and continuously under adverse conditions found in such operations, particularly, one which is selfcleansing and not liable to clog up.
It is a further object to devise a screen, and a method for its manufacture, which screen can be quickly, cheaply, and easily manufactured, and which is particularly adapted for such dry placer operations, and furthermore, one which can readily be dismounted and set up again when moving the trommel.
With the above and other objects in view, as will presently appear, my invention comprises the novel parts, and the novel combination and arrangement thereof, and also the novel method of manufacturing the screens, all as shown in the accompanying drawings, and as will be described in this specification and more particularly defined by the claims.
In the accompanying drawings I have shown my invention embodied in a form which at present is preferred by me, and have illustrated in more or less diagrammatic fashion the method of manufacturing the screens.
Figure 1 is a perspective view of the complete trommel.
Figure 2 is a longitudinal sectional view through one side of the trommel.
Figure 3 is a perspective view of a complete screen element.
Figure 4 is a perspective view, diagrammatically illustrating the first step in the method of manufacturing such screens, Figure 5 is a similar view, showing a further step, and Figure 6 .is a detail perspective view, showing a later step in their manufacture.
The trommel comprises a rotative frame consisting in general of the rotary shaft lll,=the
' wires 3.
frame bars ll, forming longitudinally spaced, squares or like polygons, and connected by'the corner frame members I2, the whole being supported from and rotatable with the shaft ID by spiders l3.placed at intervals along the'shaft. Any suitable framework, indicated generally by the numeral. 2, may be employed for supporting the shaft, and it is suitablyrotated,.provision tothis end being shown by the pulley' I4.
Usually such a trommel is provided with two or more sections, the interstices in the screen elements in the different sections being so graduated in size as to permit the passage of successivelylarger particles. As shown, the trommel is provided with two suchsections, although it will be evident that there would be nothing inventive in employing additional sections, or in omitting all but one section.
The screen elements are of peculiar character.
Such an element is'best shown in Figure 3. It 2 consists of aplurality of wires 3, which are capable of being tensioned,'secured'to end'bars '39 and 3|. Without at this time going into the method of manufacture of such screens, it'may be said that the end bars are preferably of angular shape, and the wires are secured to one of the flanges of each angle by soldering or a like process, whereby they are permanently secured, and may be stretched byseparation of the end bars. a
Within each section of the trommel such a screen element is secured in place on each of the several'sides. Thus the bar 3| may be of a length to rest upon the corner members I2, and is provided with holes 32 through which may be passed rivets or bolts 33 to securely anchor this bar to the rotative frame. The opposite end bar, however, is preferably not thus permanently secured, but is engaged by stiff spring elements 4, preferably of U shape, one end of which is'anchored'by U-bolts 4D to the frame bars ll, so that this spring continually'urges the end bar 30 toward the frame elements H and holds the screen to the rotative frame, the ends of the end bar 30 resting on the corner bars I2 of the frame,
and the action of such springs effects a tensioning of the wires 3. At this point attention is called to the plates 5 which are secured to each of the end bars, and whichextend therefrom toward the opposite end bar'for a distance, un-
derlying or being disposed inside of the screen There is provision for vibrating the wires to cause materials'which stickbetween them to'free themselves, but adjacent to the anchorageof the wires to the end bars-there-is a" zone of little or no vibration, and consequently this self-cleaning action cannot occur, but by extending the bafiies 5 to or beyond the end of this zone of minimum vibration, entrance of materials between the wires at this point is prevented. I
The means for vibrating the wires may be any found suitable. Since the trommel as a whole rotates, it will be found convenient to employ a drag 6, pivotally supported at 60 upon a frame 26 mounted upon the main frame 2, the drag being acted upon by a tension spring iii to lie in contact with and in the path of each of the wires as the trommel rotates, and thus dragging across the tensioned wires, the drag B will set each in turn into vibration, and this vibration will free the wires from materials tending to stick between them, yet there will not be suincient separation of the wires to pass unduly large particles. Moreover, the drag is located above the trommel, consequently vibration is initiated and the most intense vibration will occur in that screen which is uppermost, and particles will tend to fall back into the interior of the trommel rather than to pass through.
Any suitable provision is made for feeding material to and removing the tailings from the machine, and for receiving the classified material. I have shown a feed trough l, a waste trough 10, and classifying boxes ll and I2, as typical of any suitable arrangements to these ends which may be provided.
It has been noted that the end bars 30 and 3| extend somewhat beyond the outermost wire of the screen, to rest upon the corner bars i2, and these corner bars are preferably made of angle material, and the flanges thereof lie in the same plane as the wires of the adjoining screen, and these flanges closely adjoin the outermost wires of each such screen, thereby forming a continuation of the screen and avoiding any gap through which material might pass. I
In forming the screens, wire is unreeled from a supply reel 9 upon a frame which incorporates two removably positioned, threaded bars or spindles 90, the frame being rotatably mounted as is seen in Figure 4. The objects of the threads in the spindles 9D is to provide means for accurately spacing the wires, which as the frame and spindles are rotated is laid in two layers in each of which the wires are somewhat tensioned and accurately spaced in parallel relationship. When the spindles are full they may be removed from the rotating frame 9!, which supports them, and the spindles are then supported upon shouldered beams 92, as seen in Figure 5, where the spindles may be forcibly spaced apart to tension the wires. This may be accomplished in any suitable fashion. To this end I have shown a framework 93 including a pair of toggle arms 94 which may be acted upon by a screw jack or other power means, indicated at 95, reacting against a bar 96 of the frame 93, and thus the wires are given such tension as may be required. While under tension the end bars 30 and 3| are inserted between the two layers of wires, at accurately spaced distances, and a flange of the uppermost bar, as seen in Figure 6, is soldered or otherwise secured to all the wires in one layer, and the flange of the lowermost bar is similarly seemed to the wires of its layer. Two such bars 30 and 3| having been secured to each layer of wires, the tension may be released, the wires severed outside of the end bars, and there are thus formed two screens of like spacing between the wires. The spacing,
of course, may be varied and is controlled by the pitch of the threads on the spindles 98.
Now in setting up the trommel, after securing the bolts 33 in place, a similar frame 93 may be employed, this time bearing against the upstanding flanges of the end bars 30 and 3! to tension the wires again during such time as the springs G are being secured in place and suitably engaged with the end bars.
What I claim as my invention is:
l. A trommel comprising a rotative frame, a plurality of screens disposed about said frame to form the walls of said trommel, and disposed in longitudinally arranged sections, each screen comprising two spaced end bars and spaced parallel wires secured to and extending between the end bars, the spacing of wires in all the screens of one section being alike, but different from that in other sections, means for anchoring one end bar of each screen to the frame, and spring means engaging its opposite end bar to draw it close to the end bar of the screen in the next section, and to tension the wires.
2. A trommel comprising a shaft, a plurality of spiders carried by said shaft, a plurality of angle-irons each extending from an arm of one spider to the corresponding arm of another, lengthwise of the shaft, and disposed with the angle towards the shaft, cross bars connecting the ends of the angle-irons, to define a plurality of planiform faces, a plurality of closely spaced wires extending lengthwise of each such face, and filling the space between the flange of the angleiron at one side to the flange of the angle-iron at the other side, means to anchor the wires at one end to the cross bar at that end, and spring means to apply equal tension to all the wires, connecting the wires and the cross bar at the opposite end.
3. A trommel, for classification of material which includes hard particles, comprising a movable frame, a plurality of parallel tensioned wires spaced apart thereon to screen the material received therein, and means disposed to engage at all times directly with the wires, and engaging each wire between its ends, as the screen moves past such means, to deflect each wire in turn and to set it into vibration as the wire passes such member, whereby to dislodge hard particles from between any two adjacent wires by the vibration induced in the latter.
4. A trommel, for classification of material which includes hard particles, comprising a frame guided for movement in a given path, a plurality of parallel tensioned wires spaced apart thereon to screen the material received therein, and a rigid member fixedly positioned with respect to the path of movement of the frame to engage at all times directly with the wires, and engaging each wire individually between its ends, as the screen moves past such member, to deflect each wire in turn and to set it into vibration as the wire passes beyond such member, whereby to dis lodge hard particles from between any two adjacent wires by the vibration induced in the latter.
5. A trommel, for classification of material which includes hard angular particles, comprising a hollow rotative frame, and screens thereon formingthe side walls, each screen consisting of a plurality of spaced, pretensioned wires all extending parallel to the axis of rotation, and means to maintain them under tension, a rigid drag and spring means urging the drag to move towards the screens in a plane disposed at anv angle to the axis of rotation, the tip of said drag engaging each wire in turn, between its ends, as the frame rotates, to deflect each such wire and to set it in vibration as the wire passes beyond such member, whereby to dislodge hard particles from between any two adjacent wires by the vibration induced in the latter.
6. A trommel, for classification of material which includes hard, angular particles, comprising a movable frame, a plurality of parallel, tensioned wires supported at their ends only upon the frame, and devoid of connections between their ends, and a baiile disposed closely adjacent an end of the wires, inwardly of their points of support, to prevent entrance of material, or lodgment of hard particles, between the wires in the zone of inherent minimum vibration adjacent such points of support, the disposition of said baflies with respect to the wires permitting their undamped vibration.
7. A trommel, for classification of material which includes hard, angular particles, comprising a movable frame, a plurality of parallel, equally tensioned wires supported at their ends only upon the frame, and devoid of connections between their ends, means fixedly positioned to engage each wire individually, as the frame moves past, to set each wire in turn in vibration, and a bafile disposed closely adjacent to an end of said wires, and extending therealong, inwardly of their points of support, to a point beyond the zone of inherent 'minimum vibration adjacent such points of support, and disposed above such wires when the latter are in position to receive material, thereby to prevent entrance of material, or lodgment of hard particles, between the wires in such zone of minimum vibration, but permitting their undamped vibration beyond such zone.
RICHARD D. HELLER.