US2126031A - Vibratory screen - Google Patents

Description

Aung. 9, 1938. POPP ET AL VIBRATORY SCREEN 2 Sheets-Sheetl l Filed May Aug. 9, 193s. W. H. POPPETAL. 2,126,031

- VIBRATORY SCREEN Filed May 28, 193e 2 shets-sheet 2 Z 461/? ATTORNEYS rented Aug. 9, 193s UNITED 4STATES- PATENT' L4orifice Walter H. Popp and Edward A. Ebert, Bualm Application'May 28, 1936, Serial No. 82,287

12 Claims.` (C1. 209-326) This invention relates to a screen for separating loose material into different grades of size, and relates more particularly to a flat, inclined vibratory screen which is mounted on and is driven by a single eccentric drive shaft.

The principal object ofthe invention is to pro- -vide a vibratory screen of this'characterwhich will require the use of only one eccentric drive shaft and will, at the same time, be so arranged as to hold the screen frame at any desired angle of inclination without permitting .the` screen frame to be subjected tol periodic vibrations or unbalanced forces. Numerous other collateral objects of the invention and practical solutions thereof are disclosed in detail in the herein patent specification, wherein:-

In the accompanying drawings Fig. 1 is an. oblique top plan of'one form of our invention, taken on line ll, Fig. 2.

. Fig. 2 is a side elevation thereof.

Fig. 3 is a fragmentary, transverse and substantially vertical section through one end of the eccentric drive shaft, taken on line 3 3, Fig. 2.

' Fig. 4 is an enlarged, fragmentary, transverse and substantially vertical section through one end of the screen frame, levelling mechanism, taken on line t--, Fig. 3.

Fig. 5 is a side elevation 'of a modified form of the invention using only one aligning shaft.

Fig. 6 isa fragmentary, transverse, and substantially vertical section, taken on line 6 6,

Fig. 5.

Figs. 7 and 8 are fragmentary, longitudinal and substantially horizontal sections thereof, taken on correspondingly numbered lines ofFigs. 5` and 6, respectively.

Fig. 9 is a side elevation of another modified form of the invention using only one aligning shaft.

Fi'g. 10 is an enlarged, fragmentary, transverse andA substantially vertical section thereof, taken on line Ill-|0, Fig. 9.

Similar characters of reference indicate like parts in the several figures of the drawings.

rigs.. 1.4

The base A'of the vibratory screen is constructed of 'a pair of parallel I beams 30 which are joined together by a pair of suitable cross tie members 3l. Said base A is usually arranged at an incline, as shown, and is suitably supported in any desired manner such, for instance, as upon a foundation arranged beneath the base, or upon springs hung from suitable overhead rafters. Usually, also, the angle' of inclination 0f said the usual and well known manner.

base A is rendered adjustable by'some suitable means, but all of these particular features' of the base mounting form no part of the present invention and hence have not been illustrated.

Secured by bolts 32 or otherwise to the top faces f said I beams 3|), are a pair of stationary bearings 33 in which is suitably journaled an eccentricshaft 34. The latter is provided at its one end'with a belt` pulley wheel ,35 which is adapted to be driven from an external source of power in the usual and well known manner.

Formed integrally on the eccentric shaft 34 intermediate of its stationary bearings 33, is a. pair of eccentric collars 36, upon which are journaled a pair of bearing housings- 31. The latter are preferably secured (by welding or otherwise) to opposite ends of an alignment tube 3B. Said bearing housings 3l are provided with annular flanges 39 which are suitably secured to aipair of parallel, vertical, longitudinal side plates dll. Said side plates lit are connected transversely together by a number of suitable cross brace members and together constitute the main body of a box-like, screen frame Bin which may be mounted one or more inclined screen cloths 4l, lill in In the herein drawings, thescreen frame B is illustrated as being of the double deck type, i. e., equipped with an upper, relatively coarse-meshed, metal screen cloth 4I, and a lower, relatively fine-meshed,

metal screen cloth 4l Il. With such a double deck arrangement, any loose material, suchas gravel, coal, etc., when fed upon the feed or left end of the upper screen 4I will be separated into three size, grades, in the manner well known in the screening art.

The speed and accuracy of the separation of the loose material eiected by the vibratory screen is, of course, enhanced by causing the screen frame B to vibrate relatively to its base A, and the present invention is solely concerned with this movement and, in particular, with those vibration factors which are effected by this movement.

The load upon the eccentric collars 36 is ec centric with respect to the concentric axis of rotation of the eccentric shaft 34. To'prevent this unbalanced arrangement from causing vibrations in the base A, said eccentric shaft is balanced by two sets of counterweights 42 which are securedto companion flywheels 43. The latter are keyed to the concentric portions-of the eccentric shaft just outwardly lof the eccentric collars 36. It will be noted that the counterweights 42 of each iiywheel 43 are disposed on the inner face enl of the web of said flywheel and that their center of gravity (neglecting the weight of the ywheel) is radially in line with the center of its companion eccentric collar 36. With this arrangement and with the use of a pair of counterweight sets 42, the dynamic unbalance of all forces acting on the eccentric shaft 34 is reduced to zero and, as a consequence, any flexing of said eccentricshaft 34 is also reduced to zero, except that due to the purely static load. Any dynamic unbalance of the central part of the eccentric shaft, i. e. (the part intermediate of the eccentric collars 36) Ais eliminated by having this portion of the shaft formed concentrically with respect to the axis of the concentric end bearings 33 of said shaft.

Any unbalance of the frame B, relatively to the eccentric collars 36, is prevented by having the axes of said eccentric collars so disposed as to intersect the center of gravity of said4 frame B. Hence the axis of these collars 36 may be termed the center of gravity axis of the screen frame B. The term frame, as here used, includes all of the parts secured to or moving directly with the side plates 40 of said frame.

Secured by cap screws 44 and 45 to the outer face of the web of each I beam 3U is a pair of torsional resilient bearings 46, the resilient element of said bearings being constructed either of rubber, as shown, or of some other resilient material, such as steel, formed in the shape of a spiral or helical spring. It should be noted in this regard, that the only reason for using resilient bearings at these and at other points on the vibratory screen here disclosed is simply to provide a simple form of bearing which Will not require lubrication,-the resilient feature not being necessary because of its resilience, per se. In other words, ordinary plain bearings or antifriction bearings may be used at these and at other points on the herein vibratory screen if so desired, without affecting the action of the screen frame B but only affecting the maintenance cost.

Journaled in each pair of bearings 46 at each side of the machine is an aligning shaft 41. Secured to each aligning shaft, inwardly of each of its pair of bearings 46, is a` crank arm 48 which projects inwardly and substantially horizontally through a suitable aperture 50 formed in the adjacent portion of the web of its companion I beam 30.

Connected to the crank arm pivot l of each crank"arm 48 (either through the resilient ball and socket joint shown, or otherwise) is a linkl 52 whose upper end is connected by a resilient ball and socket joint 53, or other suitable means, to a pivot stud 54 which is secured to the companion side plate 40 of the frame B. 'Ihe total amount of movement of the screen frame B is ordinarily so small (frequently only a quarter of an inch or less) that the use of a ball and socket joint at the upper and lower ends of the links 52, is not absolutely essential. Hence, if desired, these ball and socket joints may be eliminated entirely and flexible links 52 and flexible crank arms 48 employed in lieu thereof, or both pivots of the link 52 may be plain or anti-friction bearings disposed on axes parallel to the axis of the Divot' stud 54.

By this arrangement, the screen frame B is held at a fixedangle of inclination relatively to the base A, entirely irrespective of what Sort of translatory, movement may be imparted to said frame by the eccentric shaft 34 or by any other desired means. It is obvious that the only translatory movement imparted to the screen frame B of the vibratory screen shown in the accompanying drawings is of a circular character, butthe present invention is not confined to this particular type of translatory movement and takes care of any translatory movement whatsoever.

The reason why the present invention permits translatory movement, and nothing but translatory movement of the screen frame B is as follows:

When one end of the screen frame B moves in any direction in a vertical longitudinal plane relatively to the base A, -it actuates the upper end of the link 52 at that-particular end of the screen frame. This movement causesy a movement of the crank arm pivot 5l of the companion crank arm 48 and this, in turn, causes the other crank arm pivot 5l to move a similar amount and lin a similar direction. Said crank arm pivots 5l always lie in one straight plane intersecting the axis of the aligning shaft 41, and, as the links 52 are of identical length, and as, furthermore, the distance between the pivot studs 5 4 is the same as the distance between the crank arm pivots 5l, it follows that any vertical or horizontal movement of one end of the frame permits the other end of said frame to move a like amount in a similardirection. Any tendency, however, of the one end of the frame B to move differently from the other end of the frame, either in direction or amount, is instantly resisted. I,

. One of the particular features of this invention is that any force tending to thrust the one end of the screen frame B out of proper alignment is carried in the form of a torsional stress through the aligning shaft 41 to the other end of said screen frame. The advantage of this feature is that such an aligning shaft 41 is able to carry very heavy loads, and yet oscillate back and forth in consonance with the translatory movement of the frame B, without setting up any appreciable inertia or momentum forces which tend to resist the oscillation. It is obvious, however, that the most important forces to be considered are the unbalanced moving forces and that therefore, fairly satisfactory results may be obtained if the aligning shafts 41 are journaled on the screen frame B and the outer ends of the links 52 are pivoted to the base A. l

Another vital feature connected with this construction of Figs. 1-4 is that each side plate 40 of the screen frame'B is provided with an individual restraining shaft 41. The consequence of this feature of the construction is that the frame members which connect the side plates 40 may be of extremely light construction, and yet any wracking of the frame B, taken as a whole, rendered absolutely impossible. It is to be understood that the eccentric shaft 34 takes the brunt of the dead load of the screen frame and its load,

' while the restraining shafts 41 and their appurtenances only take care of any unbalanced condition.

It is obvious from the foregoing that any periodic oscillatory vibrations of the screen frame B about the axis of the eccentric collars 36 are stopped at their very inception, although, in actual practice, a very small amount of distortion of the restraining shafts 41 and their associated parts is desirable for the purpose of cushioning any sudden heavy unbalanced force. It is desirable, however, that this distortion (which would usually be of a resilient nature, even when a shock absorber is used) is not so great as to set up excessively large periodic vibrations of the screen frame B about its axis, i. e. the axis of the Aeccentric collars 36.

` The' location `of the pivot studs 54 is of importance. In the first place, said pivot studs are so located in the present invention that their axes C and D lie in'one straight plane intersecting the axis of the screen frame B. This means that the pressures imposed upon said pivot studs 54 by the links 52 and their associated parts, are balanced as far as the axis of the screen frame is concerned. This means, in practice, that when the screen frame B (including the side plates 4i), screen y cloths 4i, 4I I, bearing housings, alignment tube 38 and all other parts which move directly therewith) has been carefully balanced on its axis, it

is not thrown out of balancewhen the links 52 are connected to said pivot studs 54.

-The location of said pivot studs 54 in a direction lengthwise of the screen frame B is also of importance when the eifect of a sudden unbalanced load force is taken into account. If we consider only the one end of the screen, say for instance the upper or feed end of the screen, we find that a sudden unbalanced load will cause the least shivering of this end of the screen, and of the screen as a whole, if the upper pivot stud 54 be located at point C about one-third inwardly from the upper end of the screen measured from the axis of the eccentric collars 36. This point is, in eilect, the percussion point for the feed end of the screenframe B. The lower pivot stud 54 is similarly located at a pointD at what may be termed the percussion point for the discharge end of the screen frame B. Ordinarily, of course,

levery moving object is considered to have only entity, and has been provided with an individual percussion point C and D to resist in the most effective manner, any unbalanced force imposed upon that particular end of the screen frame.

When the screen frame B is on its down stroke, its speed of movement is greater than the down-` ward Ispeed of theA loose material which is being screened. Hence, the loose material is not a load on the screen frame during the down 'stroke of the screen frame. When, however, the screen frame is on its up stroke, it is resisted by not only the static load of the -loose material but also by the `force of momentum of saidloose material due to the downward movement of said loose material. This may be compensated for in `various ways, but the preferred method of compensation is to "take care of this downward force by having the shaft 34, and the change of loadon the stationary bearings, is negligible. This supplying of adequate weight to the screen frame may be effected by either constructing the screen frame'B and its associated working parts of very heavy material, or it may be effected by providing special momentum weights 55. The latter are preferably secured to the outer faces of the side plates 4|] vof the' screen frame, with the axis of each weight 55 arranged coincident with the axis of its companion pivot stud 54, thereby placing the four weights at four'percussion points of the screen frame. The advantage of having separate weights 55 instead of making the screen frame B itself of heavy material,`is that in the former case 5 the screen frame is relatively light and may be easily installed and the weights 55 supplied later, whereaswhen. the screen frame itself is constructed of very heavy material, the diiflculty of installing it is considerably greater. The present 10 invention, however, includes eitherv one of these methods of opposing the sudden loads imposed by the loose material on the screen cloths 4I, 4H during the upstroke of the screen frame B.

Figs. 5-8

This inexpensive `form of the invention is similar yto the construction of Figs. 1-4 except that only one aligning shaft 41.! is employed. This shaft is journaled on the -base LI in bearings 46.| 20 and is provided with a single pair of crank arms 48.! which extend under the screen frame B.| and are so constructed as to be horizontally ilexi-f ble. Each crank arm is provided with a ball and socket crank arm pivot 5|.l which is located in a 25 vertical longitudinal plane located medially of the screen frame B.I and directly'under companion percussion pointsv E and F situated at the companion ends of screen frame. Each crank arm pivot 5|.I connects its companion crank arm with 30 a companion pivot stud 54.I which latter, in turn,

is connected to the screen frame B.| by a screen frame cross beam 5.6.

In" this construction. it will be noted that the links 52 of Figs. 1-4 have been eliminated. 35 This is because the crank arm 48.I is so long and its angular Iamount of oscillation so small that no appreciable lateral movement of the crank arm pivot 5| .I occurs as the crank arm movesup and down. Longitudinal movement of the crank arm 40 pivot 5I-;I is taken care of by the exible nature of the crank arms 481 In this construction said crank arm pivot 5|.l is located directly in the path of the descending loose material and hence means have been provided to avoid excessive abrasion of this pivot by the provision of a small metal umbrella 51 secured to the cross beam 56 just above said pivot.

are pivoted to the aligning shaft 41.2. In other words, the single aligning shaft 41.2 is journaled 55 on the base A.2 on a plain bearing 46.2, while the hub of the crank arm 48.2 is journaled in a plain, vvertical bearing 58 on said aligning shaft, and the outer end of the crank arm is connected by a plain ball and socket joint 5i.2 with the pivot 60 stud 54.2. Incidentally this construction proves that the present invention does not require anything of a resilient nature.

We claim as our invention:

1. A vibratory screen comprising: a base; a screen frame; means for gyrating said frame relatively to said base in a vertical plane; an aligning shaft-, journaled'on said base; a pair of spaced-apart arms rigidly secured to said aligning shaft and extending horizontally outward therefrom; anda vertical member m'ovably connecting the outer end of each arm with said frame.

2. A vibratory screen comprising: a base; a screen frame; means for positively gyrating said frame relatively to said base in a vertical plane; an aligning shaft journaled on said base; a pair of spaced-apart arms rigidly secured to said aligning shaft; and links connecting the outer end of each arm with the screen frame.

3. A vibratory screen comprising: a base; a screen frame; a horizontal eccentric shaft journaled on said base and extending through said frame substantially midway between the ends thereof; means mounting said frame on the eccentric portion of said shaft for positively gyrating said frame relatively to said base in a vertical plane; an oscillating aligning shaft journaled on said base; a pair of spaced-apart arms rigidly secured to said aligningshaft and arranged on opposite sides of said eccentric shaft; and links Alying in a generally vertical plane and connecting each arm with said screen frame.

4. A vibratory screen comprising: a base; a Screen frame; a horizontal eccentric shaft journaled on said base and extending through said frame substantially midway between the ends thereof; means mounting said frame on the eccentric portion of said shaft for positively gyrating said frame relatively to said base in a Vertical plane; an oscillating aligning shaft journaled on said base; a pair of spaced-apart arms connected with said aligning shaft and arranged on opposite sides of said eccentric shaft; and links each having a universal connection with the outer end of each arm and the screen frame whereby said frame is held at a. predetermined angle but is otherwise unconstrained by said aligning shaft and links.

5. A vibratory screen comprising: a base; a screen frame having vertical side walls; means for gyrating said frame relatively to said base in a vertical plane; aligning shafts journaled on said base at opposite sides of said frame and lying in a plane perpendicular of the plane of movement of said frame; spaced-apart arms projecting laterally from each of said shafts; and means movably connecting the outer ends of said arms to a companion side Wall of said frame.

6. A vibratory screen comprising: a base; a screen frame; means for gyrating said frame relatively to said base in a vertical plane; an align. ing shaft journaled on said base; a pair of spaced-apart arms connectedwithsaidshaft;and means movably connecting the outer ends of said arms with the frame said means lying in a generally vertical plane which is centrally disposed relatively to the screen frame. 5

'1. A vibratory screen comprising: a'base; a horizontal eccentric shaft journaled on said base'; a screen frame journaled on the eccentric portion of said shaft; an alignment shaft journaled on said base and having a pair of arms which base; a screen frame journaled on the eccentric portion of said shaft; a pair of alignment shafts journaled on said base on opposite sides of said frame; a pair of arms projecting laterally outward -from each of said aligning shafts; and

means movably connecting the outer end of each of said arms with said frame.

9. A vibratory screen comprising: a base; a horizontal eccentric shaft journaled on said base; a screen frame journaled on the eccentric'portion of said shaft; an alignment shaft journaled on said base and having a pair of arms which project substantially horizontally; and means movably connecting the outer ends of said arms with the frame and lying in a plane parallel to the plane of movement of said frame.

10. A vibratory screen comprising: a base; a horizontal eccentric shaft journaled on said base; a screen frame journaled upon the eccentric portion of said eccentric shaft; a screen cloth arranged in said screen frame; an alignment shaft journaled on said base perpendicularly of said drive shaft; a pair of parallelarms arranged at opposite ends of said alignment shaft;I and universal meansv connecting the outer ends of said arms with the frame.

11. A vibratory screen comprising: a base; a screen frame; a transverse eccentric shaft journaled on said base substantially midway between the ends of said screen frame; an oscillating aligning shaft extending longitudinally of said screen frame and journaled on said base; arms rigidly secured to said aligning shaft and near the ends of said screen frame; and vertical links each having a universal connection at one end With a corresponding arm and each having a universal connection at its opposite end With'said screen frame. l

'12. A vibratory screen comprising: a base; a screen frame; a transverse eccentric shaft journaled on said base *substantially midway between the ends of said screen frame; an oscillating aligning shaft extending longitudinally of said screen frame and journaled on said base; arms rigidly secured to said aligning shaft and near the ends of said screen frame; and vertical links each having a universal connection at its lower endwith a corresponding arm and each having a universal 'connection at. its upper end with said screen frame.

WALTER H. POPP. EDWARD A. EBERT.

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