US2225444A

US2225444A - Vibrating screen

Info

Publication number: US2225444A
Application number: US310091A
Authority: US
Inventors: Edwin B Gary
Original assignee: Individual
Current assignee: Individual
Priority date: 1939-12-20
Filing date: 1939-12-20
Publication date: 1940-12-17
Anticipated expiration: 1957-12-17

Description

Dec. 17, 1940. E. B.GARY

VIE RATING SCREEN 2 Sheets-Sheet 2 Filed Dec. 20, 1959 NO. I J VIII/I'lli: 7"," 5

Patented Dec. 17, 1940 UNITED STATES PATENT OFFICE 9 Claims.

This application is a continuation in part of my co-pending application Serial No. 295,391, filed September 18, 1939.

The invention relates to a vibrating screen for.

separating and grading materials such as, for example, sand, gravel, crushed stone, coke and ore and more particularly the invention is concerned with improvements in screens of the type characterized by the combination of a stationary frame, a live frame and a single. actuating shaft which. is mounted upon the stationary frame and which carries the live frame, the actuating shaft being located substantially midway between the ends of the live frame at, or in the vicinity of, the center of gravity andbeing operative to gyrate the live frame in a vertical path.

In order to maintain the live frame at the proper screening angle while permitting its positive gyration in the manner described it has heretofore been proposed to employ so-called.

equalizing springs, the latter being carried by the stationary frame and acting against the live frame at opposite. sides of the actuating shaft. Such a construction has the objection, however,

that the springs, being more or less impositive in.

their action, provide What is in effect floating supports and although, to a certain degree, they resist angular movement of the live frame upon.

the actuating shaft they do not positively prevent it, it being obvious that if the live frame is permitted to-rock as it is gyrated the paths traversed by the different sections thereof will vary as .to size and shape and that the action of such sections upon the material beingscreened will, therefore, be non-uniform. Further. ob-

jections to such a construction are that the springs are subject to frequent breakage and.

otherwise lose their effectiveness with continued use.

The principal object of the present invention isto overcome the above objections, this object contemplating the employment of a stabilizing mechanism which is operative to positively control the movement of the live frame insuch a manner, that every part is caused to. traverse a path of the same circular outline and dimensions, thereby to insure a substantially uniform screening action throughout the length of the live frame.

A further object is to provide a screen which is dynamically balanced under all working conditions, and hence which may be operated at such speeds as may be necessary to effect thorough separation of the materials, damp, wet or otherwise, without blinding and without the transmission of objectionable unbalanced impulses o-r. vibrations to the. supporting structure, this object contemplating a screen wherein the stabilizing mechanism is wholly self-sustaining and does not increase the weight, or modify the distribution of the weight, of the live frame.

A still further object is to provide a novel de sign and arrangement of the parts of the screen, whereby compactness is achieved, simplicity and economy in construction are obtained and wearing. of the parts under running conditions is minimized.

The inventionis illustrated in the accompanying drawings. in which:

Figure 1 is a top plan-view of a vibrating. screen embodying the features of the invention.

Figure 2 Ba longitudinal section taken along line 22 of Figural and shows the screen in-- clinedlat a normal working angle.

Figure. 3 is. an enlarged transverse section: takenv along line 3.-3 of Figure 2.

Figure 4 is a similar section taken alongline 4.-4 of the same figure.

Figure 5 is anenlarged detail section taken along line 5:-5 of Figure 2..

Figure 6 is an enlarged detail section of a modified form of connection for the stabilizing. arms;

The stationary, or base, frame andthe live frame of the screen are indicated at I0 and! I, respectively. The former comprises a longitudinal pair, of. spaced channel. members I2 and transverse connectingmembers l3 and may. be. mounted. upon or suspended from any. suitable. supporting structure at the desired angle of inclination. The live frame ll includes side;plates I4 between which an upper screening cloth; l5 of relatively coarse meshand a lower screening. cloth, Hi of relatively fine mesh are stretched, the .said. frame being of the so-calleddoubledecktype and being adapted, thereforato sep mate the material into three grades.

The actuating shaft, indicated'at I1, is adapt ed tosupport substantially the entire weight of the. liveframe. It is journaled in bearingsMIS which are mounted upon the baseframe members: l2; it. carries a pulley na by whichit may be driven; and it extends through a" tubular housing l9 (Figure 3) which carries. the live; frame. The said housing is mountedbetween. the side plates 1"" midway between the endsof the live frame and between the upper and lower screening'decks. Its opposite ends accommodate bearings 26 in which are journaled eccentrics ends with a trunnion 24 (Figure 4).

20a, the latter being formed or provided upon the actuating shaft adjacent its ends. When driven, therefore, the actuating shaft is operative togyrate the live frame through a vertical path, the diameter of which is determined by the throw of the eccentrics. To the end that the inertia of the live frame will not set up moments of force about the eccentrics, the actuating shaft is preferably so located that the centers of the eccentrics lie along a line which passes through the live frame substantially at the center of gravity. Flywheels 2|, which are mounted upon the actuating shaft between the sides of the live frame and the bearings l8, carry radially adjustable weights 22 for counterbalancing the eccentric load represented by the live frame, it being understood that a part of such load may be counterbalanced, if desired, by offsetting the central portion of the shaft in a direction. opposite to that in which the eccentrics 20a are offset. The transmission of unbalanced impulses or vibrations to the bearings l8, and hence to the base frame and supporting structure, is thus prevented.

In order to maintain the live frame at the proper working angle and insure a uniform circular movement throughout. its length, a stabilizing mechanism embodying the features of the invention is employed. The said mechanism, as illustrated, includes elongated arms 23 which are arranged end-to-end in pairs, one of which is located at each side of the live frame between the latter and a longitudinal member of the base frame. Each arm is provided intermediate its The latter is formed with .an annular enlargement 25, carries a bushing 26 of relatively soft rubber or like material and is mounted in a bearing 21 which is carried by the base frame, the bearing having an annular recess in which the enlargement is confined by a cap-piece 21a to prevent axial displacement of the trunnion. The inner ends of the arms, one of which overlies the other, carry studs 28 (Figure 3). The said studs are located on the sides of the arms facing the adjacent longitudinal member of the base frame; they are similar in shape to the trunnions 24; they carry bushings 29 similar to those carried by the trunnions; and they are connected by a link 30. The latter comprises companion sections which embrace the opposite side of the bushings 29 with a conforming fit and which are secured together by nut-andbolt fastening means 3|, it being noted that the studs, and hence the link, occupy a plane which extends substantially at right angles with respect to the length of the arm assembly, The outer ends .of the arms are formed on the sides adjacent the live frame with studs 32 (Figure 5). The latter are connected by rods 33 to trunnions v34 which are carried by the adjacent side plate M of the live frame at opposite sides of, and in equidistant relation with respect to,the actuating shaft, the said rods extending substantially at right angles to the arms while the trunnions are preferably located along a center line which intersects a line passing through the centers of the eccentrics 20a. The studs 32 and the trunnions being taken into consideration and compensated.

In other words, each arm, link and rod assembly is self-sustaining and is carried wholly by the base frame, Hence the said assemblies do not add to the weight of the live frame and do not have to be taken into consideration in the balancing of the live frame.

From the foregoing it will be apparent that the vertical component of the path through which the live frame is caused to travel is provided by rocking of the stabilizing arms upon the trunnions 24. Owing to their connection in the manner described, however, the arms of each pair can only move simultaneously and through the same angular distance. Their outer ends which are connected by the rods 33 to the live frame at oppo- -site sides of the actuating shaft, therefore, can

only have vertical movements which with respect to period, direction and amplitude are the same, it being noted in this connection that the links rock to compensate for the slight divergence of the arcuate paths described by the inner ends of the arms. The live frame is thus restrained so that no part can move vertically at a different time, at a greater speed or through a greater range than the remaining parts. As the arms 23 are actuated in the manner described'the rods 33 rock upon them to provide the horizontal component of the path traversed by the live frame, Every point in the latter, therefore, moves in a circular path of the same diameter. A uniform screening action throughout the length of the live frame and a constant working angle are thereby insured.

It will be noted that the angular distances through which the arms, rods and links of the stabilizing mechanism rock are relatively small as the vertical and horizontal components of the path through which the live frame is gyrated will seldom be greater than three-eighths of an inch. If preferred, therefore, the connection of the inner ends of each pair of stabilizing arms may be effected simply by a pin 38, as illustrated in Figure 6. A rubber bushing 39 which is carried by thepin will yield to compensate for the divergence of the paths traversed by the inner ends of the arms as the latter rock in the manner described, it being appreciated in this connection that such divergence will, owing to the length of the arms and the shortness of the arcs, be slight, for example of the order of one-thousandth of an inch, more or less.

Under ideal operating conditions the live frame is substantially balanced upon the eccentrics 20a of the actuating shaft and there is a minimum load upon the arms 23 as they move with the live frame. 'If, however, owing to non-uniform distribution of the material being screened, or for any other reason, the resultant forces unbalance the live frame so that one end tends to move faster or through a greater distance than the other, such forces are transmitted to the stabilizing arms and tend to rock the latter so that the connected ends of each pair are biased to the same degree but in opposite directions, The unbalancing force acting upon the live frame is thus dissipated without causing angular movement of the latter upon the actuating shaft. In other words any unbalancing forces applied to the live frame merely increase the load upon the arms, rods and links of the stabilizing mechanism. They do not influence in any way the path of movement of the live frame. For example, any force tending to rock the live frame in a clockwise direction upon the actuating shaft tends to rock the armsat the right end of the screen so that their inner ends are biased toward the actuating shaft and to rock the arms at the leftend of the screen so that their inner ends'are biased away from" the actuating shaft. The opposing forces, being equal and in opposite directions, neutralize one another. On the other 5hand, any unbalancingforce tending to rotatethe live frame in a counter-clockwise direction is resisted in alike manneras the inner ends of the arms at the left end of the screen are biased toward-the actuating shaft and the inner ends of the arms at-the right-end of the screen are biased away from it. I

In assembling the screen the bushings carried bythe trunnions 24; those carried by the

studs

28 and 3 2 and those carried by the trunnions 34 areallplaced under a compression high enough to insure a firm, non-slipping-grip betweenthe contacting surfaces of the bushings and the connected parts, The bushings, therefore, in response'to the torsional stresses to which they are subjected during operation of the screen, twist about axes parallel to the axis of the actuating shaft to permit the necessary relative angular movements between the parts of the stabilizing mechanism. Positive control of the path of movetorsion elements will not increase to any appreciable degree the power required to operate the screen as the energy which is stored in thebushings during movements of the connected parts in one direction will be released when the direction of movement of the parts is reversed.

It will be apparent that the stabilizing 40 arm-and-rod assembly at each side of the live frame, being located in a vertical plane and being carried by the base frame, is not only balanced but is wholly self-sustaining. The said assemblies, therefore, do not add 'to the weight, or modify the distribution of the weight, of the live frame. Hence, as the eccentric mounting of the latter is counterbalanced by the weights carried by the flywheels, the only load upon the actuating shaft is static and is the weight represented by the live frame.

The latter, therefore, may be accurately balanced so that it may be operated at high speeds (including speeds at which the downward moveso only loadto which the stabilizing mechanism is subjected is that represented by the non-uniform distribution of the material screened. The

said mechanism may, therefore, be light and com-pact in design, it being noted in this cones nection that the studs at the ends of each of the arms 23-are located on opposite sides of the arm. Hence any force applied to one end of an arm which tends to tip its trunnion in one direction is neutralized by the equal, and similar, force 70 which is applied to the opposite end of the arm. The trunnion, therefore, has no tendency to cant in it's bearing.

Apart from the lightness of the stabilizing mechanism it is to be noted that as each pair 1,1301 arms and the associated connecting rods operatein a vertical plane and: that as all of the axesof the various pivotal connections are parallel to the axis or the actuating shaft, the longitudinal members of the base frame may be arranged--as-= close to the sides of the live frame as the fly 5 wheels will 'permit. This renders the construction compact'and has the further advantage'that whippingof-theshaft'ia minimized.

' I claim as my invention:

l-fA vibrating screen comprising a supportingqo 5 frame,alive frame, said live framehaving sides" between which -a screening element is stretched, a horizontal actuating shaftcarried by the" supporting frame, saidshaft'passing through said sides, having eccentrics upon which the live 15' frame-is mounted and being so located that the centers of the eccentrics li'e along .aline substantially coincident with the center of gravity of'the live frame, means for driving said shaft to thereby gyrate said live frame in a vertical path, 26*" means carried by said shaft for counterbalancing the eccentric mounting of said live frame, stabilizin'g arms arranged lengthwise of said live" frame in end-to-end relation and individuallymounted on said supporting frame for rocking 25- movement in vertical planesyrods arranged substantially at right angles with respect tosaid arms,- said'rods having pivotal connections with" the outer ends of said arms and with said live frame'at opposite sides of saidshaft and meansto connecting the inner ends of said arms so that their angular movements, although in opposite directions, are simultaneous and of substantially the same amplitude, thereby maintaining said live frame in the proper screening position and effecting a substantially'uniform gyratory movement throughout its length despite non-uniform distribution of the load and other forces which tend to cause it to rock in a vertical plane.

2. vibrating screen comprising a supportingA frame, a live frame, a horizontal actuating shaft carried by the supporting frame, said shaft being located substantially midway between the ends of said live frame and having eccentrics upon which the latter is mounted, means for driving 45' said shaft to thereby gyrate said live frame in a vertical'path, stabilizing arms arranged lengthwise of said live frame in end-to-end relation and individually mounted for rocking movement in vertical planes, links arranged substantially at 56 right angles with respect to said arms, said arms and links being pivotally connected to one another and the assembly thus provided having pivotal connections with the supporting frame and with said live frame at opposite sides of said shaft and means connecting the adjacent ends of said arms so that their angular movements, although in opposite directions, are simultaneous and of substantially the same amplitude, thereby maintaining said live frame in the proper screenan ing position and effecting a substantially uniform gyratory movement throughout its length despite non-uniform distribution of the load and other forces which tend to cause it to rock in a vertical plane. 51s

and individually mounted on said supporting 5; 1'

frame for rocking movement in vertical planes, rods arranged substantially at right angles with respect to said arms, said rods having pivotal connections with the outer ends of said arms and with said live frame at opposite sides of said shaft and means connecting the irmer ends of said arms so that their angular movements, although in opposite directions, are simultaneous and of substantially the same amplitude, thereby maintaining said live frame in the proper screening position and effecting a substantially uniform gyratory movement throughout its length despite non-uniform distribution of the load and other forces which tend to cause it to rock in a 'vertical plane.

4. A vibrating screen comprising a supporting frame, a live frame, a horizontal actuating shaft carried by the supporting frame, said shaft having eccentrics upon which the live frame is mounted and being so located that the centers of the eccentrics lie along a line substantially coincident with the center of gravity of the live frame, means for driving said shaft to thereby gyrate said live frame in a. vertical p.ath,stabilizing arms arranged lengthwise of said live frame in end-to-end relation, having'overlapping inner ends, and being individually mounted on said supporting frame for rocking movement in vertical planes, rods arranged substantially at right angles with respect to said arms, said rods having pivotal connections with the outer ends of said arms and with said live frame at opposite sides of said shaft and means connecting the inner ends of said arms so that their angular :movements, although in opposite directions, are simultaneous and of substantially the same amplitude, thereby maintaining said live frame in the proper screening position and effecting a substantially uniform gyratory movement throughout its length despite non-uniform distribution of the load and other forces which tend to cause it to rock in a vertical plane.-

-5. A vibrating, screen comprising a supporting frame, a live frame, a horizontal actuating shaft carried by the supporting frame, said shaft beinglocated substantially midway between the ends ofsaid live frame and having eccentrics upon which the latter is mounted, means for driving said shaft to thereby gyrate said live frame in a vertical path, elongated stabilizing arms arranged lengthwise of said live frame in end-to-end relation and individually mounted substantially midway between their ends upon said supporting frame for rocking movement in vertical planes, rods arranged substantially at right angles with respect to said arms, said rods having pivotal connections with the outer ends of said arms and with said live frame at opposite sides of said shaft and means connecting the inner ends of said arms so that their angular movements, although in opposite directions, are simultaneous and of substantially the same amplitude, thereby maintaining said live frame in the proper screening position and effecting a substantially uniform gyratory movement throughout its length despite non-uniform distribution of the load and other forces which tend to cause it to rock in a vertical plane.

6. A vibrating screen comprising a supporting frame, a live frame, a horizontal actuating shaft carried by the Supporting frame, said shaft'being located substantially midway between the ends of said live frame and having eccentrics upon which the latter is mounted, means for driving said shaft to thereby gyrate said live frame in a vertical path, a pair of stabilizing arms arranged in end-to-end relation at each side of and lengthwise of said live frame, each of said arms being individually mounted intermediate its end. upon said supporting frame for rocking movement in a vertical plane, rods arranged substantially at right angles with respect to said arms, said rods having pivotal connections with the outer ends of said arms and with both sides of said live frame at opposite sides of said shaft and means connecting the inner ends of said pairs of arms so that the angular movements of the arms of each pair, although in opposite directions, are simultaneous and of substantially the same amplitude, thereby maintaining said live frame in the proper screening position and effecting a substantially uniform gyratory movement throughout its length despite non-uniform distribution of the load and other forces which tend to cause it to rock in a vertical plane.

7. A vibrating screen comprising a supporting frame, a live frame, a horizontal actuating shaft carried by the supporting frame, said shaft being located substantially midway between the ends of said live frame and having eccentrics upon which the latter is mounted, means for driving said shaft to thereby gyrate said live frame in a vertical path, stabilizing arms arranged lengthwise of said live frame in end-toend relation and pivotally mounted upon said supporting frame for rocking movement in vertical planes, rods arranged substantially at right angles with respect to said arms, said rods having pivotal connections with the outer ends of said arms and with said live frame at opposite sides of said shaft and means including a pivot pin for connecting the inner ends of said arms so that their angular movements, although in 01)- posite directions, are simultaneous and of substantially the same amplitude, thereby maintaining said live frame in the proper screening position and effecting a substantially uniform gyratory movement throughout its length despite nonuniform distribution of the load and other forces which tend to cause it to rock in a vertical plane,

the axis of said pivot pin being parallel to the axis of said shaft. I 8. A vibrating screen comprising a supporting frame, a live frame, a horizontal actuating shaft carried by the supporting frame, said shaft being located substantially midway between the i ends of said live frame and having eccentrics upon which the latter is mounted, means for driving said shaft to thereby gyrate said live frame in a Vertical path, stabilizing arms arranged lengthwise of said live frame in end to-end relation, being pivotally mounted upon said supporting frame for rocking movement in vertical planes and having overlapping inner ends, rods arranged substantially at right angles with respect to said arms, said rods having pivotal connections with the outer ends of said arms and with said live frame at opposite sides of said shaft and a link connecting the inner ends of said arms, said link having spaced pivot pins located in a plane which extends substantially at right angles with respect to the length of the arm assembly and having axes parallel with the axis of said shaft so that the angular movements of said arms, although in opposite directions, are simultaneous and of substantially the same amplitude, thereby maintaining said live frame in the proper screening'position and effecting a substantially uniform gyratory movement throughout its length despite nonuniform distribution of the load and other forces which tend to cause it to rock in a vertical plane.

9. A vibrating screen comprising a supporting frame, a live frame, a horizontal actuating shaft carried by the supporting frame, said shaft being located substantially midway between the ends of said live frame and having eccentrics upon which the latter is mounted, means for driving said shaft to thereby gyrate said live frame in a vertical path, stabilizing arms arranged lengthwise of said live frame in end-to-end relation and individually mounted for rocking movements in vertical planes, links arranged substantially at right angles with respect to said arms, said arms and links being pivotally connected to one another and the assembly thus provided having pivotal connections with said supporting frame and with said live frame at opposite sides of said shaft, torsion elements of rubber or the like which are held under compression between the parts of said connections and which are adapted to twist about aXes parallel with the axis of said shaft to permit relative angular movement between said parts and means connecting the inner ends of said arms so that their angular movements, although in opposite directions, are simultaneous and of substantially the same amplitude, thereby maintaining the live frame in the proper screening position and effecting a substantially uniform gyratory movement throughout its length despite non-uniform distribution of the load and other forces which tend to cause it to rock in a vertical plane.

EDWIN B. GARY.