US2042072A - Screening apparatus - Google Patents

Description

May 26, 1936.

S. D. ROBINS SCREENING APPARATUS Filed June 21, 1932 5 Sheets-Sheet l y 1936. s. D. ROBINS 2,042,072

SCREENING APPARATUS Filed June 21, 1932 5 Sheets-Sheet 2 May 1936- s. D. ROBINS 2,042,072

SCREENING APPARATUS Filed June 21, 1932 5 Sheets-Sheet 5 y 1936- s. D. ROBINS SCREENING APPARATUS Filed June 21, 1952 5 Sheets-Sheet 4 May 26, 1936. s D, ROBINS 2,042,072

SCREENING APPARATUS Filed June 21, 1932 5 Sheets-Sheet 5 Patented May 26, 1936 SCREENING APPARATUS Samuel Davis Robins, Hewlett, N. Y, assignor to Robins Conveying Belt Company, Passaic, N. 8., a corporation of New Jersey Application June 21, 1932, Serial N... 618,434

15 Claims.

This invention relates to vibratory screens wherein uniform orbital paths of motion in planes at right angles to the screening surface are simultaneously imparted to the latter.

The principal object of the invention is to provide a screen of such construction that uniform paths of motion are imparted to the screening surface throughout its area, and this without limitation of such paths to any specific orbital contour, thus affording provision for the eflicient screening of a wide variety of materials.

Another object of the invention is to provide a screen wherein the angle of inclination of the screening surface can be readily adjusted without affecting the paths of motion of the screen frame.

Another object is to provide a screen wherein the amplitude of vibration of the screening surface can be readily adjusted as desired.

Another object of the invention is the provision of novel means for arching and tensioning the screen cloth.

With these and other objects in view my invention comprises novel features of construction and combinations of parts which will be hereinafter described, the scope of the invention then being expressed in the appended claims.

In the drawings Figure 1 is a side elevation of a screen embodying the preferred form of my invention, the motor support being partly broken away.

Fig. 2 is a transverse vertical section of the apparatus, as on the line 22 of Fig. 1, showing the motor.

Fig. 3 is a perspective view of the main supporting frame, the springs thereon, and the vibrator carried by the springs.

Fig. 4 is a similar view of the motor support and the motor thereon, showing the flexible coupling on the motor shaft.

Fig. 5 is a section through a part of the motor support, showing the adjacent ends of the motor and vibrator shafts, and the flexible coupling therefor.

Fig. 6 is a longitudinal vertical section of the vibrator.

Figs. 7 and 8 are transverse vertical sections of the vibrator, as on the lines 1--'I and 8-8, respectively, of Fig. 6.

Figs. 9 to 14, inclusive, are sections through the tubular vibratory element and the gyratory mass element therein, showing modifications of the contactual surfaces of the respective elements, whereby the orbital path of the vibratory element can be varied.

(Cl. 209-326) l Fig. 15 is a perspective view of the screen cloth supporting frame.

Fig. 16 is a longitudinal section of said frame and its appurtenances, showing the screen frame as mounted in the vibratory live frame. 5

Referring to the drawings, A designates a supporting frame comprising, in the present instance. longitudinally flanged side plates 20, end flanges 2| bolted to the respective plates, and an I-beam 22 connecting said plates in spaced parallel relation.

B designates a live frame comprising two spaced side plates 23 provided with one or a series of screen decks C, in the present instance two.

In the screen cloth mounting herein illustrated each of the screen cloths 24 is supported under tension by and upon .a skeleton frame structure including side rails 25 and end crossbars 26, 21 which are rigidly supported by suitably-disposed angle brackets 28 and bolts 29 on the side plates of the live frame.

One end of the screen cloth is securely clamped against the end bar 26 by means, for example, of an angle bar 30 and screws 3|, and the opposite end of the cloth is similarly secured to the upper edge of a rockable tensioning bar 32 on the outer side of the end bar 21.

In the present instance the tensioning bar is provided on itsinner surface with a longitudinally extending bevelled shoulder 33 which is seated against and fulcrumed on the lower outer edge of the bar 21. The depending portion of the bar is connected by tensioning rods 34 with U- brackets 35 amxed to spaced longitudinal bars 36 on the skeleton frame structure, which rods pass 35 through holes 31 in spaced transverse bars 38 on the structure and are provided at their inner and outer ends with heads 39 and adjusting nuts 40, respectively. Hence by properly manipulating the nuts the tensioning bar can be adjustably 40 tilted to effect the requisite tensioning of the attached screen cloth.

In order to maintain the rigidity of the screening surface and prevent the whipping and crystallizing of the cloth, provision is bad for a slight arching or crowning of the tensioned cloth, and since, particularly in the case of very fine screening, it is important to keep' the arch as fiat as possible to ensure a more even distribution of the bed of material over the screen, the screen surface is subdivided into several low arched sections, thus providing throughout the area of the screen a substantially flat surface made up of a plurality of independently arched portions.

To this end the frame and the spaced longltudinal and transverse bars 36 and 38 are relatively arranged to provide a plurality of rectangular openings the walls of each of which are slightly arched, as at 4|, to aflord longitudinally and transversely extending crowning supports for the adjacent portion of the screen cloth. The cloth is secured, as by screws 42, to the arched supporting bars at their points of intersection, thus subdividing the tensioned screen surface into a plurality of independently arched sections, as previously mentioned. (See Figs. 2, 15 and 16.)

D designates a vibrator including a tubular vibratory element 43 extending transversely of the live frame and projecting at its ends through suitably-disposed openings in the side plates 23. This element is provided adjacent its ends with circumferential flanges 44 which in the present instance are welded thereto, and which flanges are bolted to the respective side plates so that the live frame shall partake of the motion of the vibratory element. The projecting ends of the vibratory element 43 constitute trunnions which are seated in and firmly held by split clamps 45 that are fastened to the upper horizontal members 46 of angularly bent leaf springs, whereof the vertical members 41 rise from and are securely bolted to the end flanges 2| of the adjacent side plates 20 of the base frame.

The vibrator is positioned in the clamps and locked thereby to the springs, thus maintaining the screen in any desired inclination for screening, it being noted that the clamps provide a convenient means for the adjustment of the angle of inclination of the live frame. The springs support this frame with its vibrator in a. stable yet yielding manner; stable so that the frame will stand at whatever angle is chosen, and yieldable so that not only will the frame be permitted to vibrate with freedom, but also so that no serious amount of escaping impulses from the vibrating frame will be transmitted to the base frame and floor supports.

The vibrator as herein shown is located at or relatively close to the center of gravity of the live frame and its appurtenances to insure uniformity, or substantial uniformity within practical limits, of the paths of motion of the various points of the live frame. The purpose of fastening the springs at or close to the center of gravity is to avoid what might be called the spring resistance couple. In operation the vibration of the live frame causes a displacement or flexure of the supporting springs, and since the displacement is caused by the action of the vibrator it follows that if the resultant line of force of the combined springs passes through or relatively close to the vibrator axis and center of gravity axis, no appreciable "spring resistance couple can exist, but if, on the other hand, this line of force passes some distance below or above either of such axes, there is present a spring resistance couple which, while having negligible effects at high operating speeds, tends to disturb the uniformity of the paths of motion at low speeds.

The leaf springs 46, 4lare made of substantially rectangular form as herein shown for the reason that the orbits of motion of all parts of the live frame lie in vertical longitudinal planes, and such orbits represent both vertical and longitudinal components of motion. The horizontal portions of the springs accommodate the vertical components of motion and the vertical portions of the springs accommodate the horizontal components of motion; it being noted that the springs are relatively rigid in transverse directions so that while freedom is afforded for flexure in vertical longitudinal planes, the whole structure is stably prevented by the springs from sidewise movement.

By the described resilient mounting of the live frame and its associated vibrator the operative orbits of motion of the live frame may be varied within wide limits. For example, the path of motion imparted to the frame may be circular or substantially so; it may be a long narrow ellipse, the major axis being inclined at any angle in the vertical longitudinal plane that may be desired; it may be such an ellipse with the major axis constantly rotating in the vertical longitudinal plane, or it may be generally circular with a point or high spot on one side, that is, pear-shaped, with the stem extending up or down or at any angle that may be desired.

The variable motion capacity of the apparatus is an important one in the screening art since the particular motion imparted to the screening surface plays a prominent part in the behavior of the material on the screen surface. For example,

motion at a slight angle to the surface has a powerful propelling action on any loose material resting upon the surface, and therefore such a screen can be set at a very small inclination, and plant head room thereby saved; and in the pearshaped motion a rapid deceleration and accelera tion takes place at the stem of the pear where the direction of the moving point suddenly changes. the practical advantage of such a motion residing in the ability of the screening surface to free itself from adhering cementitious material.

The vibrator herein disclosed is of the general construction described in my co-pending application Serial No. 585,061, (Patent No. 1,901,122, dated March 14, 1933) which construction includesan operating shaft 48 co-axial with the vibratory element 43 and journaled in bearings 49, 50 in the respective end heads 5| and 52 of said element. This shaft extends through and beyond the end head 52 and is flexibly connected with and rotated at high speed from a suitable source of power, as, for example, by means of a flexible hose or coupling 53 between the vibrator shaft 48 and the shaft 54 of an adjacent electric a surface having a rapid rectilinear reciprocating motor 55. This motor may be conveniently supported by a standard 56 aflixed to one of the side supporting plates 20.

On the shaft 48, adjacent the inner sides of the respective end heads, are two counterpart bodies comprising annular members 51 which are coupled to the shaft so as to rotate positively therewith, yet are free to assume any eccentric rela-" tion within limits to the axis of rotation of the shaft, each member thus constituting a "floating" eccentric.

A roller 58 comprising an annular member of any desired mass surrounds the shaft 48 and is slightly smaller in diameter than the interior of the tubular vibratory element 43. This roller is rotatably mounted at its ends on the respective members 51, suitable anti-friction bearings 59 being preferably interposed between the floating eccentrics and the internal, wall of the roller.

The roller 58 is provided at its respective ends with circumferential race members 60 adapted to co-act with the opposing inner surfaces of race members 6| within the ends of the tubular vibratory element 43. The outside diameter of each of the members 60 is smaller than the inner diameter of the co-acting member GI and therefore byvirtue of theslidable or floating mounting of the bodies 51 on the shaft 48 a measurable eccentricity is maintained between the mass roller and the shaft during the rapid rotation of the latter, thus producing a gyration of the roller with consequent generation of centrifugal force thereon.

' Consequently a continual state of rolling contact is maintained between the mass roller and the element 43, and the centrifugal force set up in the roller is transmitted as an orbital vibrating impulse to the-element and the screen frame associated therewith.

The inner surfaces of the contact members 6! are correspondingly tapered, as shown, so that in accordance with different longitudinal adjustments of the roller 58 and its contact members variations of the ratio of the outside diameter of each of the members 68 to the inside diameter of the contiguous member 8| at the point of contact can be readily effected, in order that the amount -of centrifugal impulse of the mass roller at any given speed of rotation of the shaft 48 can be adjusted to vary the amplitude of vibration of the live frame and the screening surface.

For this purpose the driven end of the shaft 48 is slidably mounted in the bearing 50 in the adjacent head 52 of the vibratory element 43, and the bearing 49 for the other end of the shaft is mounted in a casing 62 which is slidably fitted in a cavity in the end head SI of the element 43. An adjusting screw 63 is threaded in the wall of the head 5|, so as to bear centrally against the opposing wall of the casing 82, and hence by properly manipulating the screw 63 the casing and its bearing 49, together with the shaft 48 and its appurtenances, can be adjusted to determine the endwise location of the mass roller 58 and the relative positions of the contact surfaces of the members SI of the roller with respect to the contact surfaces of the members 80 of the element 43, and this while the apparatus is in operation.

The orbital path of the vibratory element 43 can be readily varied to meet particular screening requirements; for example, if the internal contact surface of the race ring 6| of the element 43 be slightly elliptical, as represented in Fig. 9, the mass roller in its active gyratory travel in contact with such surface will impart an elliptical path to the element 43. So also, if, as representedin Fig. 10, the race ring 60. of the mass roller be slightly elliptical, an elliptical path will be imparted thereby to the element 43 during the gyratory travel of the roller.

If the continuity of the internal circular contact surface of the race ring SI of the element 43 be interrupted by a depression, as indicated at 64 in Fig. 11, or by a raised portion, as indicated at 65 in Fig. 12; or if the race ring 60 of the mass roller lie interrupted by a raised portion as at 68 in Fig. 13, or by a depressed or flattened portion as at 61 in Fig. 14, the orbital path of the vibrating element 43 in each case will be influenced by the opposed impulse or impression during the rotation of the roller, and in consequence periodic jarring efiects will be transmitted to the live frame and its appurtenances.

In the constructions illustrated in Figs. 9, 11 and 12, itis apparent that the interruptive portion of the race ring SI of any of the elements 43 can be adjusted to any desired angular position in relation to the axis of the shaft by partially turning the element on its end heads and then securing it at the desired position of adjustment.

It is to be understood that my invention is not limited to the specific constructions herein disorbital paths, a supporting frame, and springs connected to said supporting frame and vibrator at the respective sides of the live frame, said springs each having a substantially horizontal portion and vertical portions extending therefrom and movable in directions substantially at right angles to each other wholly supporting the live frame and vibrator, said springs being constructed and arranged to accommodate the vertical and horizontal components of motion of the live frame by the action of the vibrator.

2. In a screening apparatus, a live frame including a screening surface, a vibrator including a vibratory element having an operating shaft extending transversely across the live frame fixec to and supporting said live frame and having outwardly projecting end portions surrounding the shaft and extending beyond the sides of the frame, supporting springs at the respective sides of the live frame, each spring having a substantially horizontal portion and vertical portions extending therefrom, and means fixedly connecting the projecting end portions of the vibratory element to the horizontal portions of the respective springs.

3. In a screening apparatus, a live frame including a screening surface, a vibrator including a vibratory element having an operating shaft extending transversely across the live frame fixed to and supporting said live frame and having outwardly projecting end portions surrounding the shaft and extending beyond the sides of the frame, supporting springs at the respective sides of the live frame, each spring having a substantially horizontal portion and vertical portions extending therefrom, and clamps for securing the projecting end portions of said vibratory element ing a vibratory element fixed to and supporting i said live frame and having outwardly projecting end portions, an operating shaft journaled in said end portions, leaf springs at the respective sides of the frame, each spring comprising a horizontal portion and vertical end portions, base members to which said vertical end portions are secured, and clamps on the said horizontal portions for securing the projecting end portion-s of said vibratory element to said springs, the said springs forming the sole support for the live frame and the vibrator.

5. In a screening apparatus, a live frame including a. screening surface, a vibrator comprising a vibratory element fixed to and supporting said live frame, said element having its longitudinal axis extending transversely of the frame and relatively close to the center of gravity of the frame, a shaft journaled in and wholly supported by said vibratory element co-axially with the latter, and a mass element operatively mounted on said shaft to rotate therewith and contact with and actuate the vibratory element, and substantially rectangular spring structures for supporting the respective ends of said vibratory element, said structures extending longitudinally of the live frame.

6. In a screening apparatus, a live frame including a screening surface, a vibrator comprising a vibratory element fixed to and supporting 7. In a screening apparatus, a live frame in-' cluding a screening surface, a vibrator comprising a vibratory element fixed to and supporting said live frame with its axis relatively close to the center of gravity of the frame, a shaft journaled in and wholly supported by said vibratory element co-axially with the latter, and a mass element operatively mounted on said shaft to rotate therewith and contact with and actuate the vibratory element, and springs supporting said vibra-.

tor at the respective sides of the frame having a substantially horizontal portion and vertical portions extending therefrom and movable in directions substantially at right angles to each other, said springs forming the sole support for the frame and vibrator and being constructed and arranged to accommodate the vertical and horizontal components of motion of the live frame by the action of the vibrator.

8. In a screening apparatus, a live frame including a screening surface, a vibrator comprising a. vibratory element fixed to and supporting the respective sides of the live frame and having outwardly extending end portions, a shaft journaled in and wholly supported by said vibratory element co-axially with the latter, a mass element operatively mounted on. said shaft to rotate therewith and to contact with and actuate the vibratory element, and supporting springs to which the respective projecting end portions of the vibratory element are fixed, each spring having a substantially horizontal portion and vertical portions extending therefrom and movable in directions substantially at right angles to each other, said springs forming the sole support for the frame and vibrator and being constructed and arranged to accommodate the vertical and horizontal components of motion of the live frame by the action of the vibrator.

9. In a screening apparatus, a live frame including a screening surface, a vibrator comprising a vibratory element fixed to and supporting the respective sides of the live frame and having outwardly extending end portions, a shaft journaled in and wholly supported by said vibratory element co-axially with the latter, a mass element operatively mounted on said shaft to rotate therewith and to contact with and actuate the vibratory element, supporting springs at the respective sides of the .live frame, said springs each having a substantially horizontal portion and vertical portions extending therefrom, and clamps on said horizontal portions of said springs for securing the projecting end portions of said vibratory element to said springs, the said springs forming the sole support for the live frame and the vibrator.

10. In a screening apparatus, a live frame including a screening surface, a vibrator comprising a vibratory element fixed to the respective sides of the live frame and having outwardly extending end portions, a shaft journaled in and wholly supported by said vibratory element coaxially with the latter, and a mass element operatively mounted on said shaft to rotate therewith and to contact with and actuate the vibratory element, leaf springs at the respective sides of the frame, each spring comprising a horizontal portion and vertical end portions, base members to which said vertical end portions are secured, and clamps on the said horizontal portions for the projecting end portions of said vibratory elemen 11. In a screening apparatus, a. supporting frame,a live frame for a screenhaving side plates," atubular element extending through said side plates and connected thereto, a mass element for vibrating the live frame in the tubular element, a spring at each side of the live frame connected to the supporting frame, and means for connecting the tubular element to the springs.

' 12. In a screening apparatus, a supporting frame, a live frame for a screen having side plates, a tubular element extending through said side plates and connected thereto relatively close to the center of gravity of the live frame, a mass element for vibrating the live frame in the tubular element, a spring at each side of the live frame connected to the supporting frame, and means for connecting the tubular element to the springs.

13. In a screening apparatus, a supporting frame, a live frame for a screen having side plates, a tubular element extending through said side plates and connected thereto relatively close to the center of gravity of the live frame, a mass element for vibrating the live frame in the tubular element, a spring at each side of the live frame connected to the supporting frame, and adjustable means for connecting the tubular element to the springs whereby the angle of the live frame may be varied about the axis of the tubular element.

14. In a screening apparatus, a live screen frame, a vibrator having an operating shaft extending transversely of the live screen frame connected to the screen frame and forming the sole support for said screen frame, a spring arranged at each side of the screen frame and having a substantially horizontal portion and vertical portions extending therefrom, a bearing mounted on the horizontal portion of each spring for said shaft, and means for locking the bearings, springs 1 and screen frame against relative movement.

15. In a screening apparatus a live screen frame, a vibrator having a tubular element extending transversely through the screen frame and secured thereto, an operating shaft extending through said tubular element, a bearing for the shaft connected to each end of the tubular element, a spring arranged at each side of the screen frame and having a substantially hori-

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