US2112886A - Screening device - Google Patents

Description

April 1938. J. E. GREENAWALT 2,112,886

SCREENING DEVICE Original Filed March 8. 1935 4 Sheets-Sheet 2 FIGB.

I /v VEN TOR JOHN E GREENAWALT BrA fk A TTORNEY I April 5, 1938. J. E. GREENAWALT 2,112,886

SCREENING DEVICE OriginalFiled March 8, 1935 4 Sheets-Sheet 3 FIG] FIG. IO. 55

I N VEN TOR (JOHN E. GREENA WALT ATTORNEY April 5, 1938. J. E. GREENAWALT SCREENING DEVICE Original Filed March 8, 1935 4 Sheets-Sheet 4 IN VENTOR HN L. GHEENAWALT A TTORNEY Patented Apr. 5, 1938 UNITED STATES PATENT OFFICE Application March 8, 1935, Serial No. 9,977 Renewed August 9, 1937 7 Claims.

My invention has relation to improvements in. screening devices and consists in the novel features of construction more fully set forth in the specification and pointed out in the claims.

The invention is particularly directed to a screening device for separating heterogeneous mixtures of material, such as city refuse which includes garbage, ashes, boxes, rags, papers, etc. While the invention is designed primarily for the screening and separating of such material into graded sizes it will, however, be equally effective on other materials, such as crushed ore, coal, etc., and because of its ability to efiectively handle heterogeneous mixtures it is even more efiective for rapidly and efficiently screening crushed masses of similar material.

The principal object of the invention is to provide a screen that will be subjected to a gyratory motion at its extremities to cause a vigorous vibration or whipping movement of the screen elements which prevents the lodgment between screen elements of irregularly shaped pieces of material and pieces of limp material, such as rags. The motion of the screen is such that should pieces of material being screened fasten themselves to the screen elements they will not long remain so fastened but will in a short time be shaken loose.

A further object of the invention is to provide means for varying the degree of vibration imparted to the screen so that the screening effect may be regulated according to the material being operated on. The vibrating screen is also constructed in such a manner so that the violent movement to which it is subjected is cushioned so that it will not be subjected to excessive wear, and so that it will not be communicated to the building in which the screen is installed.

The vibration and motion of the screen is such that the grading action or screening of the material proceeds continuously without clogging. I find that this is accomplished most efficiently by vibrating the screen elements at a high rate of speed through a small amplitude which causes the material to move down the inclined" screen during the grading operation. Due to the heterogeneous character of the material and moisture content the particles have a tendency to stick together to form clots and some of the fine mate rial that should pass through the screen would be trapped in crumpled or crushed paper and other limp ingredients of the mass. The vibratory motion of the screen is such as to break up such clots and free the fine material from other particles in which it may be trapped, and

at the same time prevent fine, moist material from adhering to the screen elements. The screen motion also prevents the wedging of lumps of material between the screen elements. In short, the construction of the screen together with the motion imparted thereto is such that the material is quickly and effectively spread over the entire screen and the grading proceeds so that the screen is at all times comparativel clean. i

Preferably the upper andlower ends of the screen are not vibrated in unison, but have different vibratory periods or amplitudes so as to accentuate the whipping action of the individual screen elements, thereby introducing a differential of motion between adjacent elements which furthers the screening action and makes it practically impossible for lumps of material to become wedged between adjacent elements. In some cases it may be desirable to have the screen ele-t ments gyrate only at the upper end, and in other cases, to have the elements gyrate at both ends with the gyration at the lower end being through a smaller arc.

These objects, as well as the advantages inherent in the invention, will be better apparent from a detailed description of the same in connection with'the accompanying drawings, in which:

Figure l is a side elevation of my improved screen showing the middle part thereof broken away and the upper bearing support shown in section; Fig. 2 is a front elevation of the screen with the intermediate part broken away; Fig. 3 is a vertical, cross-section taken on a plane indicated by the line 3-3 in Fig. 1; Fig. 4 is a vertical, cross-section taken on the line 4-4 in Fig. 1; Fig. 5 is an enlarged longitudinal, sectional detail taken on the plane indicated by the line 5-5 in Fig. 3; Fig. 6 is an enlarged longitudinal, sectional detail takenon a plane indicated by the line 6-6 in Fig. 4; Fig. '7 is a horizontal section taken on a plane indicated by the line 1-1 in Fig. 1 with parts left in elevation; Fig. 8 is a cross-sectional detail of one of the brackets for supporting a screen element, said section taken on a plane indicated by the line 88 in Fig. 5; Fig. 9 is an enlarged sectional View of a bearing and portion of the upper shaft of a modified form of the invention; Fig. 10 is an enlarged sectional view of a bearing and portion of the lower shaft of a modified form of the invention; Fig. 11 is a longitudinal, medial section through the lower end of a modified form of the screen; and Fig. 12 is a cross-section taken on a plane indicated by the line l2l2 in Fig. 11.

Referring to the drawings, I, I represent concrete foundation members constructed in step shape, on the lower part of which are base castings 2, 2 and on the upper part base castings 2', 2'. The supporting surfaces 3, 3 of the base castings 2, 2' are inclined so as to give the desired inclination to the channel members 4, 4, 4, 4 on which my improved screen S is mounted. The screen comprises screening elements 5, 5, etc., carried by upright arms 6, 6 at the upper end .of the screen and 1, 1 at the lower end thereof, which arms are mounted on supporting shafts 8 and;.9 at the upper and lower screen ends, respectively. The upper shaft 8 is supported in bearings I0, I8 carried by spring suspended plates I I, I of bearing supports I2, I2, and the lower shaft 9 is supported by bearings I3, I3 Fcarriediby spring suspended plates I4, I4 in bearing supports 15,15. The bearing supports |2, I2 are securelyJoolted to the upper ends of channel members 4, '4 andthe bearing supports I5, I5 are securely bolted to the lower ends of said channel members.

The bearing supports I2 and I5 are similarly constructed and a description of'one will serve for all. Each of said supports comprises a boxlike casting having side walls I6, |6 provided with centrally disposed recesses I1, .11 and laterally extending lugs I8, "I8 at the ends of 'said side walls. The side wallsralso haveihorizontally disposed flanges I9, I9 adjacent their lower ledges through each of which is .azbolt 'hole '20 for receiving a'bolt 2| by means .of'which the bearing support is secured to the-channels 4, :4. There are bottom portions 122, :22' formed integrally between the side walls 46, v|6,.said bottom portions being spaced apart so as to .leave the center of thecasting open at the-bottom.

In'the upper surfaceof each bottom portion 22 is an annular depression --23 to=serve as aspring seat, and extending downwardly throughthe bottom' portion and centrally-disposed with respectto the spring seat .is a square passageway 24 to receive the eye125 of :an eye bolt126. The eye bolts 26, 26 each have two superposedcoiled springs 21, 28 disposed on them, and between the springs 2-1, .28 on the eye-bolts the ibearing plate II is mounted. A spring cap-30 is'disposed over the upper end of each spring 26, and nuts -3|, '32 screwed over the threaded extremity 33 :of the 'bolt26 :hold thebearing plate II firmly between the springs '21 and .28. The bearing :plate "I I is provided with openings 34, 34 to accommodate the bolts 26, 26,and:a pair of spring seats 35, 36

areformed around the openings :34 to accommodateboth pairs of springs 21(28 and'hold them securely in place. A spring'seat v31'is bolted to eachpairiof lugs LI8, |8at thaends of the bearing support casting through the opening 38 in which an eye-bolt 39 passes,the eye 40 at the-inner end thereof being :connected byzmeans-of a pin 4| betweenears "42, 42 projecting from the end of bearing plate 'I I. A spring 43 .is disposed over the bolt '39 and held in operative engagement with spring seat31 by a spring cap 44 held in place on the eye-bolt'39 by means of nuts45, 46 screwed on the threaded extremity 41 of the bolt. The connecting of the eye- bolts 39, 39 between the ears 42, 42 permits the necessary pivotal movement to take place between these two parts during the operation of the screw. The bolts 26, 26 are connected to the bottom members 22,22 of the bearing support by pins 48, 48 disposed in the pin holes 49, 49 passing through the bottom members 22, 22 and intersecting with the openings 24, 24 therein. The eye-bolts 26,126 are free to move pivotally on the pins 48, 48 as required during the vibrations of the screen in operation. The bearing plates II, II and I 4, I4 have roller bearings I0, I 8 and I3, I3, respectively, mounted on them and secured in place by bolts 5|. The ends 52, 53 of shaft 8 are mounted in the upper bearings I0, I0 and the ends 54, 55 of shaft 9 are mounted in the lower bearings I3, I3. It will be observed by referring to ,Figs. 3 to 6, inclusive, that bo-ththe upper and lower shaftszland 9 are 10 unbalanced. That is, the shaft 8 has portions 56,

56 just inside the end portions 52 and 53 that are eccentric with respect to the balance of the shaft in that=the center line a: for these portions 56, 56 does not coincide with the center line x of the I.) balance of the shaft. On these eccentric porz tions'56, 56 of the shaft 8 the upper end of the screen S is carried by means of links or arms 6, 6,

on .theends of which bearing boxes 59, 59 are formed for roller bearings 6|, 6|. A cross bar 62 in the form of a pipe is mounted in roller bearings 6|,.6I, said cross bar .62 carrying in juxtaposition a plurality of bracketsz63-extending from one end to the other of the'bar in contacting relation and maintained in position by collars 64, 64

fixed on the cross bar 62 by means of set- screws 65,65 just inside the bearing boxes 59, 59.

The upper ends of the screen elements or bars 15.. are each enveloped by a sleeve 66 and rest on a concave seat61 formed on the upper end of each' bracket-63. A flanget68 extends rearwardly from the bracket 63 and is perforated as are the screen element5 and sleeve66 to receive a bolt 69 which secures the upper end of the bar firmly to the bracket '63. As stated above, the shaft 9 is also unbalanced as the portions 10, 10 are eccentric with respect to the balance of the shaft, as indicated by the center lines y and y.

Bearings boxes 1|, 1| are mounted *on the eccentric portions 10,10 of the shaft 9 and are eachud provided with upwardlypresented flanges '12, 12. The-flanges", 1201 the bearing boxes 1| support a cross'member 13 havingangle pieces 14, 14' at itsen'ds which rest on the flanges 12, 12-andare secured thereto by means of bolts 15, 15. The;1 i5 cross member 13is in the form of a T-ibeamsand carries the lower ends of thescreen elements'5. Sleeves 16 are disposed over the lower ends of said screen elements and a bolt 11'passes throughthe sleeve16, element 5 and outerfiange of the cross:,:0 bar 13. It will be observed that the upper sleeves 66 and'lower sleeves 16 contact with each other so as to effectively space the screen .elementsr5 from each other.

On the extremity 53 of the shaft 8 and theextremity 54 of shaft!) are mounted pulleys P, P, respectively, so that these shafts are driven independently of each other. Thus either shaft may be rotated, the other remaining stationary, or the speed of either shaft may be varied so as to regulate the action of the screen according to the material that is being screened.

In the operation of my improved screening device the rotation of the shafts 8 and 9 will impart a gyratory motion to the links 6,6 and' bearing housings 1|, 1| since, as explained above, these members are mounted on eccentric portions of the shafts. This gyratory motion will of course be imparted to the ends of the cross bar 62 and the ends of cross member 13 communicat- 70 ing the gyrations to these members. Since the screening elements 5 are carried on the members 62 and 13 they will be vigorously vibrated by the gyrations of their supporting members, and owing to their length will also'undergo a certain amount of whipping motion so that no two bars will necessarily vibrate in unison. In other words, while the screening elements all receive their motion from the same actuating members they will move more or less independently and thereby produce a very effective screening action. I have found that this vibrating, whipping motion of the bar 5 is very efiective in preventing limp pieces of material, such as rags, from becoming fastened to the bars, and if such pieces of material should become wrapped around any of the ,bars it will in a short time be again dislodged.

Since each end of the screen is independently actuated the lower end may be vibrated at a high rate of speed with comparatively small amplitude, while the upper end may be oscillated at a comparatively slow speed with relatively large amplitude. Owing to the link support at the upper end of the screen the motion of the lower end will be substantially parallel to the plane of the screen. The character of the motion imparted to the lower end of the screen may be varied by adjusting the tension of the vertical springs 26, 21 and horizontal springs 43 from an elliptical motion with the major axis of the ellipse parallel to the plane of the screen to an elliptical motion with the major axis of the ellipse perpendicular to the plane of the screen, or at any angle between these two extremes. The upper end of the screen will be oscillated in a direction parallel to the plane of the screen with a large amplitude compared to the lower end of the screen so that the material near the upper end of the screen will not merely slide along the screen but will be jogged downwardly. Due to the link connection at the upper end of the screen and the pivoted connection at the lower end, the motion created by the unbalanced shaft 8 at the upper end of the screen will gradually decrease in amplitude downwardly of the screen until it finally disappears at the lower end of the screen.

When the two ends of the screen are actuated at the same time the vibratory motion imparted by the lower shaft will be superimposed upon the jogging or oscillating motion imparted by the upper shaft, and the screen as a whole will undergo a vigorous, irregular whipping motion in combination with the vibration and oscillation. The jogging at the top of the screen will be effective to loosen up clumps of moist material and fine material that may be entrapped in crumpled paper, rags, or similar pieces, and will also quickly spread the material over the entire screen, producing a rapid and regular screening action. The vibratory motion and the whipping action operates effectively to prevent the moist, fine material from sticking to the bars, and coarser lump material from becoming wedged between the bars. The vibratory motion of the small amp-litude will also contribute largely to maintaining the continuous screening action and feeding the material downwardly along the screen. Since this vibratory action is most prominent at the lower end of the screen it will allow the coarser material to lie close to the bars and settle into slots after the finer material has passed through fur' ther up on the screen.

In summing up, the following are some of the conspicuous characteristics of the screen:

1. Possesses a jogging and vibratory action with a superimposed irregular whipping of the bars essential to the grading of a mixture composed of materials differing widely in physical characteristics.

2. The differential of movement between the bars prevents material from becoming wedged, and also prevents limp material, such as rags, from working down the screen without being graded.

3. The jogging action will loosen up adhering material and cause the smaller material to quickly settle down and pass through the screen elements.

4. The variability of the motion at the lower end of the screen by the adjustment of the springs makes it possible to cause the material to move either more rapidly or slowly as it approaches the bottom of .the screen.

The vertical springs 35 and 35 also serve to cushion the vertical thrust produced by the oper-" ation of the screen and the horizontal springs 43, 43 likewise absorb the longitudinal thrust so that the vibrations of the screen will not be imparted to the supporting structure or building containing the same.

In the modification shown in Figs. 9 and 10 the construction of the upper and lower shafts 8i] and Bi is slightly different. Instead of having a shaft formed with eccentric journal portions 56, 56 for the upper shaft and Ill, 10 for the lower shaft, as in the main form, the shafts are now unbalanced with respect to their rotation axes; that is, the entire shaft 89, between the journal portions 82, is eccentric with respect to the end portions of the shaft, and the entire shaft 8| between the journal portions 84 is eccentric with respect to the extremities of the lower shaft. Since the extremities of the respective shafts 8B and 8| are mounted in their respective spring suspended bearings H] and i3 the unbalanced portions of the shafts will cause a violent vibration and impart a vertical reciprocation or gyration to the screen carried on them.

In the modification shown in Figs. 11 and 12 the lower ends of the screen elements or bars 5 are mounted on saddles 85 supported from the supporting plate 86 by upwardly extending webs 8?. The webs 81 are of substantial height so as to elevate the bars considerably above the supporting plate 88 which has terminal flanges 88, by means of which the plate 86 is secured to the bearing housing TI. The bearing plate 86 is curved downwardly to the rear for the purpose of expediting the discharge of fine material passing between the bars 5 and dropping on said plate. Any rags or limp material m that ride down on the bars 5 encounter no obstructions by virtue of the elevated saddles 85 and are free to slide oh the ends of the bars. However, should pieces of material fall between the bars and lodge on the plate 86, the quick vibratory movement to which this plate is subjected will gradually propel such pieces forwardly over the plate as indicated (Fig. 11).

Having described my invention, I claim:

1. A screening device comprising an upper and a lower pair of bearing supports, hearings in said supports, cushioning means interposed between each bearing and its support, a transversely disposed shaft mounted in each pair of bearings, a screen carried by said shafts, said screen comprising a plurality of bars individually mounted, screen supporting journals in spaced relation on each shaft, suitable connecting members between the screen and shafts and swiveled on the journals thereof, and said journals being eccentrio with respect to the rotation axis of their respective shafts.

2. A screening device comprising an upper and a lower pair of bearing supports, bearings in cal said supports, cushioning 'means interposed between each bearing and its support, a transversely disposed shaft mounted in each pair of bearings, a screen carried by said shafts, said screen comprising a plurality of individually supported bars, means for rotating said shafts, and said shafts being unbalanced so as to gyrate the screen supports on rotating the shafts.

3. A screening device comprising an upper and a lower pair of bearing supports,-bearings in said supports, cushioning means interposed between each bearing and its support, a transversely disposed shaft mounted in each pair of bearings, a screen carried by said shafts, said screen comprising a plurality of individually supported bars, means for independently rotating said shafts, and said shafts being unbalanced so as to gyrate the screen supports on rotating the shafts.

4. A screeningdevice comprising an upper and a lower pair of bearing supports, bearings in said supports, cushioning means interposed between each bearing and its support, a transversely disposed shaft mounted in each pair of bearings, a screen carried by said shafts, suitable connecting members between the screen and the shafts, means for rotating said shafts, and said shafts being unbalanced so as to gyrate the screen supports on rotating the shafts, said screen comprising a plurality of juxtaposed bars of relatively small diameter compared to their length so as to undergo a whipping action during the gymtions of the screen supports.

5. A screening device comprising an upper and a lower pair of bearing supports, bearings in said supports, cushioning means interposed between each bearing and its support, a transversely disposed shaft mounted in each pair of bearings, a screen carried by said shafts, screen supporting journals in spaced relation on each shaft, suitshafts.

able'connecting members between the screen (and shaftsand swiveled on the journals thereof, said screen comprising a plurality'of juxtaposed screen elements individually supported by the connecting members at one end of the screen, and said journals being eccentric with respect to the rotation axis of their respective shafts.

6. Ascreening device comprising an upper'and a lowerpair of bearing supports, bearings .insaid supports, cushioning means interposed betweeneach bearing and its support, 'a transversely disposed shaft mounted in each pair of bearings, a screen carried by said shaft, screen supporting journals in spaced relation on each shaft, suitable connecting members between the screen and shafts and swiveled on the journals thereof, said :screencomprising a plurality of juxtaposed screen elements individually supported by the connectingrmembers atthe upper endof the screen and collectively supported bytthe connecting members at the lower end of .the screen, and said journals being eccentric with respect to the rotation axis of their respective shafts.

.7. .A screening device comprising an upper and va'lower pair of bearing supports, bearings in said supports, springs suspending the bearings in a ;manner toabsorb the vertical'thrust thereon, and

JOHN E. GREENAWALT.

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