US1417681A

US1417681A - Concentrator

Info

Publication number: US1417681A
Application number: US132387A
Authority: US
Inventors: Gustave A Overstrom
Original assignee: Individual
Current assignee: Individual
Priority date: 1916-11-20
Filing date: 1916-11-20
Publication date: 1922-05-30
Anticipated expiration: 1939-05-30

Description

G. A. OVERSTHOM.

CONCENTRATOR.

APPLlcATmN HLED/ Nov. 2o. 1916.

Patented May 30,1922;

' fnuenon MAW GUSTAVE A. OVERSTROM; OF PASADENA, CALIFORNIA.

Y UONCENTRATOR.

nemesi.

Specication of Letters Patent.

Patented May 30, i922.

Application filed November 20,1916. ,Serial No. 132,387.

To all w hom it may concern:

Be it known that I, GUsTAvE A. OVER- s'rnoM, a citizen of the United States, resid ing at Pasadena, county of Los Angeles, State of Californiahave invented a new and useful Concentrator, of which the following is a specification.

This invention relates to those types of concentrators in which a reciprocating motion keeps the material moving, while a low of water forwet Work, or gravity and skim-l ming` rililes for dry work, accomplishes the separation while the material is in motion.

The main object of the invention is to provide a greatly simplified construction, adaptable to handle a'vvide range ofv sizes and so simple that the most unskilled laborer can understand it.

Another object is to make a grit and sand proof head motion, eliminating the use of slides, toggles, rockers, eccentrics, cams, etc., and all but one bearing, therebyv eliminating repairs.

A further object is to provide, without impairing theeffectiveness, al construction so cheap to build'that machines of this class may reach the man of limited means, and of such nature that repairs can be made in any out ol theway mining camp.

Alnother object is to produce a concentrator automatically operating at a constant speed, although there may be a variation in the speed of the motive power.

A still further object is to construct and oporatea concentrator structure on the pendulum principle, thereby reducing strains to a minimum, consequently prolonging the lil'c of the structure, and requiring the least possible power to operate. l

.l further object is to provide a simple tilting adjustment between the shaking frame and the table top. and to concentrate the tilting. stroke and water adjustments at one point. therebymaking it possible for a man to attend to more tables than he otherwise could do.

Other objects and advantages of my invention will appear hereinafter.

ln the drawings I have soown well known type of coneentrator, known as a transversely inclined concentrating table with diagonally ending riftles.

Referring thereto, Figure l is a plan view.

Figure 2 is a vertical, longitudinal section through the center of the structure, plainlyl illust-rating thebuling means and the tilting adjustment.

Figure 3 is a vertical, longitudinal section through the table top, taken near the lower side of the table, showing the full view of the floor and shaking frame and the means for hinging the table top -to the shaking frame.

Figure 4 is a cross-sectional elevation, taken about half way from the end of the table.

Figure 5 is an end elevation, looking at the discharge end of the table.

The invention comprises a frame adapted to move in a substantially horizontal direction, an unbalanced revolving weight attached to the frame and adapted to impart movement thereto, means for producing a constant speed differential `reciprocatlng movement therefrom, andv a concentrating sur-face adjustably attached to the shaking frame.

It is desirable, but not absolutely necessary, that the concentrator structure be so supported that naturally it will'oscillate or beat time at the rate which, by experience, has been found to give the best separating results; hence the center of gravity of the reciprocating part of the Structure is of 1 such a distance from the point of fulcrum, or bending, and so supported that a pendulum is produced, which, when given a slight assistance, will oscillate at the desired number of strokes per minute. As a consequence the strains set up in the reciprocating structure and the power required to move it are reduced to a minimum.Y It follows naturally that it is best to apply the powergiving the impulses at the same rate as the pendulunr time. lt is also desirable, but not necessary, to naturally limit the pendulum movement to a length nearly corresponding to the average length of stroke which by practice has been found to give best results; hence the oscillating structure is supported b v springs of a stiffness suitable to give the desired length of movement` thereby produc,-v ing a c vwloidal pendulum. lt is a well known law that the time of a pendulum is independent of the length `of oscillation; hence if by suitable means the length of oscillation is varied, the time will remain the same.

This feature is important, as the time or rate of speed in a concentrating mill is the tot only element entering into the lseparating problem, which is not supposed to vary considerably. To take care of other varying elements,-adjustments (such as amount of water, incline, length and nature of stroke) must be provided.

When at times, as unavoidably will happen, the speed of the motive power will vary, the separating work done by the usual concentrator becomes very indifferent and poor. In accordance with the principles of my invention this undesirable result is avoided as will be more fully hereinafter explained.

In the concentrator here described .the time of oscillation tries to remain uniformly the same, and actually does so within fairly large limits ofincrease or decrease in the v speed of the motive power,.providing the sol belt, connecting the motive power to the revolving unbalanced weight, is small and loose enough to slip to some extent. On account of the power required to operate this table being very slight, the unbalanced revolving weight is small and the belt is unusually small and loose as compared to other tables doing similar work; hence when increase inthe speed of the motive power does occur, the belt slips slightly and the table operates at its natural uniform speed in spite of the increase in power.

In the drawings I have shown a transversely'inclined concentrating table of well knownoutline, and referring to the drawings in detail: The table top (l) may be of any suitable construction; I have shown it with the usual linoleum surfacev and riflles.

The top (1) is tiltingly attached from cross beams (2) of table top (l) to the movable frame (3) by'means of hinge bolts (4)' pass'- ing through the beams (2) and a hinge membei` (5), (which in this case for conA venience is an extension of a'member of a different function), attached to frame (3),

and the interposed multiple tilting wedge' (8), the thread part of which is effectively protected from grit or splashing water and 'dirt 'by this means.V Brackets V(10) and (12) help take away the thrust on the hinges from the upper half of the table. A block 4 (13) nailed on the upper forward corner of the table keeps sand and water from dropping on the tilting adjustment parts.

-Flexible supports (14) preferably made .of hickory or locust. wood, support/the Shak.i

ing frame (3) with the attached top (1) in A substantially horizontal movable position. The supports V`(14e) have a thin center portion (15) and club feet ends (16) and (17), four of the ends (16) continuing upwards for some distance and formingv the before mentioned hinge member The ends (16) are keyed solidly to brackets or recesses (18),l attached to frame (3) and also bolted to frame (3).v The 'ends (17 are similarly keyedand bolted to recesses in the stringers (19) of the floor frame.

[This forms a flexible support, allowing the table to reciprocate in a horizontal direction, without any joints to oil or wear out, and at the same time, when properly proportioned, lthe llexible supports, together with the weight attached thereto, form an inverted cycloidal pendulum, which when set in motion will oscillate in the time and to the distance desired. When I refer to the supports 14 as being flexible I wish it to be understood as meaning that said supports are resilient so as` to have a natural rate of vibration similar to the vibrations of a resilient spring Yin order to securethe inverted cycloidal pendulum action above described.

These supports lmay be made t'o stand at more or less incline; lfor roughing work tiltedback as muc-h as 72o from the horizontal, and in such case, a marked differential movement is obtained without the use of springs or bufling means; however, as such a motion'is not horizontal, there is in wet concentration a disturbance of the water which is detrimental when treating fines and slimes; hence, for best all around results thesupports are only tilted back enough so that on the extreme forward stroke they stand almost vertical and the differential is obtained by other means.

For a reciprocating motion a hollow shaft (20) is clamped fast in the end of frame (3).

Mounted on the shaft (20) is the purposely unbalanced loose pulley (21) and the balanced loose pulley (22), both held 1n position by set collars (24) The unbalanced pulley is provided in any suitable manner with adjustable weights (25) of any desire-d size,

form, or material, of which more or less can frame is a'bumping post (27), in the upper end of which is seated a'soft rubber buffer (28), A rod. (29) having a. small pitch nemesi thread and tail nut (30) at. each end, adjustably connects the bumping post (2T) below the buffer to the cross beam (3l) of the floor frame. A bracket (32) fastened to the cross beam (33) of the floor frame, holds up the center of the rod (29) keeping it from vibrating. The stringers (19) are bolted to the cross beams (22'6), (31) and (33).and this structure forms what I have termed the floor frame. The cross beams are bolted solidly to a floor or preferably a foundation. The rod (29), in place of attaching to a cross beam, may be attached to any rigid point outside of the table structure itself. YVhen the table is reciprocating, the bumping post is drawn up by means of tension rod (29) s o that the center beams (34) of shaking frame (3) touch or strike the rubber buffer (28) more or less hard, according to the kind of motion desired. By this means the motion of the table is arrested in its'forward Hight, and the loose material resting on the table surface advances. The table also starts back rapidly, due to the back push of the buffer and the tension set up in the bumping post and tension rod b v the bump. @n the forward stroke the start is slow, due to inertia of a body at rest. rfhe total result is a differential motion, capable of a wide range of adjustment.

Many other arrangements and constructions may be used for this purpose. ln practice ll find, however, that the arrangement illustrated gives uniformly the best all around satisfaction. l also find that the rubber buffer gives better results than coil springs, which unless properly constructed and adjusted.. besides being used in pairs. each spring of different size. at times will cause synchronous vibration to set in, which never occurs when the construction shown is used.

ln the operation of the table, power is applied by means of a belt indicated at (35). This belt may run in either direction and need not necessarily be vertical, but can be about 30 out of vertical one way or the other. lf more than 300. there is some slap tothe belt, which in course of time would weaken the belt, otherwise the slap of the belt does not affect the operation. The stroke of the table being usually g to l, this amount of movement does not affect the running of the belt so 4that it can be noticed.

lVhen the belt is shifted to the unbalanced pulley, the table reciprocates` and the advancing speed of the material being separated is adjusted by drawing up or loosening up on either one of the tail nuts on the tension rod. `Weight can be added or taken from the unbalanced pulley.

Feed is supplied to the table for about one-third of the length of the upper side of table near head met-ion end. lin case of wet separation, wash water is applied from a boa along the remainder of same side, coming from a pipe located above the wash water box at the upper right hand corner in Fig. l, about where blockl(13) is located. Yhile the material moves forward towards the right hand end (see Fig. l), the wash water moves the material down towards the iower side washing the lighter material over the riffles and finally over the lower side, while the heavier material is carried by the riflies towards the right hand or discharge end of the table. the flow of the water so that the edge always will be keptwet.

Referring to Fig. l, in wet concentration the surface A G F is covered by practically nothing but water from the incoming feed, which water runs off over lower side of table from G to F. The surface A B E F is covered by mostly waste product which runs over the lower side of table from F to E. The surface B D E is covered by the concentrate or heavier portions of the material, and is kicked over the end of the table from D to E. r)The surface B C D is usually only covered by the wash water of which but very little leaves the table from C to D.

lf a long stroke and gentle motion are required, l. use average amountof counterweight on p-ulley and ease up on the tension god, lf a short and sharp stroke is required, l use average counterweight and draw up on the tension rod. Long sha-rp stroke is obtained by more counterweight and more tension. Short gentle stroke is obtained by less counterweight and less tension. As a rulel the c-ounterweight is seldom changed after it has been found to be large enough, so that the motion is not disarranged by quite. a large variation in the amount of load, but the stroke adjustment is done by This end is slightly' angular to simply shortening or lengthening on the tension rod; shortening, which also shortens the stroke, makes the material travel slower; lengthening makes material travel faster, with the proviso however that. the tension rod is not lengt-hened to the 'extent that the shaking frame'will hardly touch the buEer.

The manner here described of supporting a concentrator and imparting differential motion to same, forms a combination so simple known cam driven bumping tables in use twenty to forty or more years ago. The motion itself being a noiseless floating motion, can not be heard at all, and only a gentle dull and barely audible sound is observedwhen the structure is arrested in its flight by the 'rubber buffer.

The center pieces of the shaking frame continueyin one unbroken length from the lbuffer to the hollow shaft and take up the inertia of the structure directly in a horizontal direction from the buffer to the head motion Without passing through any joints which would be llable to give out, therebfylf` insuring long life to the shaking frame. he'tension rod in turn brings the shock in almost a horizontal direction back to the foundation and back of where the table top is supported, thereby Owing to the fact that almost any rate of travel desired can be obtained in this table,

it is natural .that most operators would em-V ploy al fairly fast rate so as to obtain great capacity; hence this table in outline is made longer and narrower than is usual in other tables. It also follows that the necessity for making short and wide tables for treating slimes, which are hard to move by the usual reciprocating motion, will disappear, and one type and shape of table will serve the purpose for` all sizes of material, consequently having a universal application.

This invention contains three separate and distinct featureswhich are preferably, but not necessarily, interdependent.

Thegfirst is a concentrator construction de-v signed to operate on the principle of a pendulum. Any slight mechanical assistance made to operate in the same time as the natural oscillation of the pendulum will operate it. The table can be operated by a child pushing or pulling4 with one hand by simply following up the natural oscillation yof the structure, giving at each stroke a slight assistance. child operates it with more ease than a large man, because the large man is barely able to follow up a motion as fast as re uired in this case.

o illustrate: In the full size commercial machine, which is designed to operate at 240 strokes per minute, with an average length of stroke of 13,/'16', when the table top is removed, `which lowers the center of gravity thereby shortening the pendulum, the natural number of strokes per minute becomes 380; and a large powerful man can not start the frame vibrating, but a small delicate man, especially one who does'no hard work, has no trouble whatever by pushing or pulling with his thumb and forefinger in starting the frame to vibrate and kee ing it going for a long time. When the tab e top is attached to the shaking frame, the center of gravity alters and the natural oscillations become 240 per minute and the strong man is able to opcrate it, but not with the same ease as' the smaller man. This proves conclusively that the mechanical assistancevshould by 'right beat time lwith the pendulum, and when it does the power required is but very small. Any mechanical assistance given to this pendulum construction and operated in time with it, will produce similar results.

The second feature is a reciprocating motion produced by a revolving weight attached to the reciprocating member. The table here described can be and has been operated at a greatly different speed from its natural vibration, but under thosev conditions it takes correspondingly more power and more counf.y

the heretofore known head motions, which are, as far as I am aware, stationary. It is the inertia in the revolving unbalanced pulley that starts and keeps the structure in motion, and it is the inertia in the pendulum structure that makes it possible to drive this at a constant speed with but only power enough to convey the material being `separated and overcome the internal friction in the flexible spring supports.

By attaching the means for producing impulse directly to the reciprocating structure and reciprocating with it, I avoid the ham* mering and counter-shock to the structure that has always heretofore accompanied the use of bumping blocks in concentrators. Such counter-shock is due to the fact that the force giving the impulse has been developed at a fixed point, and not on the reciprocating structure itself.

It is a well known fact that what is known as a bumping table in the art, can make slimes move ahead that cannot be moved by other reciprocating motions, in spite of the back lash caused by cams or the like, but the secondary vibration set up by the back lash is detrimental to saving of slimes. plicants device there is no secondary vibration nor back lash, but the material travels on the reciprocating surface without the retrograde movement usually present in other devices used for the same purpose.

It 'will be observed that the weighted or unbalanced pulley revolves on a relatively stationary shaft instead of a revolving shaft. Consequently the bearing bushing in the unbalanced pulleyx any degree wit in limits without producing In the aplost motion-or shock. This is due to the fact that no wear'takes place on theside of the bushing where the unbalance in weight is carried but all of the wear takes place on the side of the bushing opposite the location' of v the unbalance in weight, that is, on the side of the bushing where the reaction occurs. If, however, the unbalanced pulley should be mounted to revolve with a shaft, the latter revolving in journal bearings, then the action of the unbalance'in weight is to cause lateral movement of the shaft from one side of its'bearing to the other. This produces wear in the shaft bearing with the consequent development of lost motion and an undesirable shock which seriously interferes with, if not destroying, the concentrating action. V Consequentlythe feature of mounting the unbalanced pulley to revolve upon a relatively fixed axle or shaft is an important one in accomplishing the objects and purthe rtable, as well as the noise and vibraposes of my invention.

Differential motion obtained by cams, etc., in combination with springs or gravity act"- ing against a bumping post, is an old well lmown device, and the rapid destruction of tion produced by these devices, are equally well known. This noise and destruction is not present in a Structure embodying my invention, due to the floating, in place of the stationary, means employed and due also to the manner in which lost motion is automatically eliminated through -the mounting of the unbalanced pulley to revolve upon a relatively fixed axle or shaft and without the introduction of any other elements except the force developed by the unbalanced revolving pulley.

Many variations in the details of'construction and arrangementy would .readily occur to persons skilled in the art and still fall within the Spirit and scope of my invention.

I do not desire, therefore, to' be limited or restrictedl to the exact details of construction shown and described, but

Having now set forth the objects and nature of my inventionand a construction embodying the principles thereof, what I claim as new and useful and of my own invention and desire to secureby Letters Patent is:

l. The combination, in a conoentrator, of a horizontally reciprocating frame, and flexible supportstherefor, a concentrating table hingedly mounted upon said frame, a shaft at. one end of said frame, and an adjusting device at the other, an unbalanced power driven wheel mounted on said shaft, whereby, when said wheel is rotated, a reciprocating movement will be transmitted to said frame and table."

2. Thecombination, in a concentrator, of a horizontally reciprocating frame, and Hexi ble supports therefor, a concentrating table hingedly mountedupon said frame, a shaft on said frame, an unbalanced power driven wheel mounted on said shaft for imparting a vibratory movement to said frame and table, and means for tensioning said bumper for suddenly arresting said movement in one direction to a desired degree.,

'3. The combination, ina concentrator, of 4 a horizontally reciprocating frame, and exible supports therefor, a concentrating taf ble hingedly mounted upon saidr frame, a shaft on said frame, an unbalanced power driven wheel mounted on said shaft for imparting a vibratory movement to' said frame and table, and means for suddenly arresting said movement lin one direction toy vshaft to the element, abumper block carried by said connections and reciprocating therewith, and a bumper with which said ,block engages.

GUsTAvn A. 'o'vERsTRoMl