US1459845A - Screening machine and screen cloth therefor - Google Patents

Description

B. MITCHELLV SCREENING MACHINE AND SCREEN CLOTH THEREFOR Filed Sept. 30 1920 3 Sheets-Shea?, l

z C /Ca i Jun@ 26, E923. L45945 B. A. MITCHELL SCREENING MACHINE AND SCREEN CLOTH THEREFOR Filed Sept. 30 1920 v3 Sheets-Sheet 2 Jun@ Z6, 11923. l

B. A. MHTGHEILL SCREENING MACHINE AND SCREEN CLOTH THEREFOR Filed Sept. 30 1920 3 Shwtcsheeb 5 to the heavy wires on screen cloth for use Patented June 26, 1923.

UNITE-D STATES PATENT QFFICE.

BENJAMIN A. MITCHELL, OFGARFIELD, UTAH.

SCREENING MACHINE AND SCREEN CLOTH THEREFOB.

Application led September 30, 1920. Serial No. 418,843.

To all whom zit may concern.'

Be it known that I, BENJAMIN A. MITCH- ELL, a citizen of the United States, residing at Garlield, in the State of Utah, have invented certain new and useful Improvements in Screening Machines and Screen ,Cloth Therefor, of which the following is a` speciication. v

This invention relates to improvements in in screening machines and to improvements in such machines fox` screening finely divided or crushed materials.

The

principal Vobject of the invention is to provlde an improved screen cloth havingv or heavy wlres interwoven relatively large with the comparatively fine wires which compose the body portion of the screen. Another object of the invention is to provide a woven wire' screen cloth reinforced with heavy wires, in which the dimensions of the meshes of the cloth, transversely to the heavy wires, are substantially uniform throughout the screen. Still another object is to provide a Woven wire screen cloth having relatively large wires of approximately elliptical or oblong cross section interwoven with the fine wires of the screen. Other objects relate to various features of construction and arrangement such as will be more fully pointed out hereinafter.

The nature of the invention will be understood from the following specification taken in connection with the accompanying drawings, in which certain embodiments are illustrated.

In the drawings-` Fig. 1 shows a top plan view of the improved screen cloth;

Fig. 2 shows a sectional view transversely Fig. 3shows a longitudinal sectional view on the line 3 3 of Fig. 4, illustrating one method of connecting the screen cloth to the screening machine;

Fig. 4 shows a top plan view of a screening machine with the improved screen cloth embodied therein;

Fig. 5 4is a perspective view of the machine-illustrated in Fig. 4 looking toward the underside thereof;

Fig. 6 shows-a side elevation of the screening machine with a feeding device shown in vertical section;

Fig. 7 shows an enlarged vertical section throughthe screen cloth transversely t0 the ffound that, by

the line 2-2 of Fig. 1;'

of the vlbrations which may screen cloth; y

The form of screen cloth illustrated particularly in Figs. 1 and 2 comprises a plurality of longitudinal weft wires 15 which are interwoven with a plurality of transversely extending warp wires 16'. The wires l5 and 16 are comparatively small in cross section and the wires 15 have substituted therefor, at predetermined intervals, the comparatively large weft wires 17 which are preferably oblong or approximately elliptical in cross section, as illustrated in Fig. 2. The ne wiresl 15 and 16 are spaced equal distances aparty to form meshes 18, which are substantially rectangular and it has been employing heavy wires 17 of oblong cross section, it is possible t6 maintain the meshes 18 uniform in size throughout .the width of the screen cloth. If the heavy wires'17 were circular in cross section and of a diameter equal to the shorter dimensions of these wlres, as illustrated in Fig. 2, it will be apparent that the meshes 18a on each side of each heavy wire would have dimensions transversely to the heavy wires greater than the corresponding meshes formed by the interwoven fine wires. The use of a heavy wire having an oblong cross section overcomesthis difficulty, due to the fact that the projecting lateral edges of the heavy wires partially fill the meshes so that the openings 18a adjacent the heavy wires can be maintained the same in size as any e set up in the p ,of the other meshes formed by the fine wires v alone.

The screen cloth thus formed is particularly adapted for use in screening meshes for screening orV separating crushed ore, sand, gravel, or other similar materials which are caused to pass over the screen cloth, preferably while it is being vibrated. lhe heavy wires give an increased stiffness to the screen cloth and are adapted to increase the etliciency of the vibratlons therein and, while at the same time, the provision of a uniform size of mesh makes it possible to maintain a uniform ineness "of the screened material.

Th application to a screening machine of screen cloth made in. accordance with this Ainvention. The machine here shown comprises a frame 2O having a centrally located cross frame member 2l united at its ends with upwardly extending arms 22. These memere is illustrated in Figs. 4, 5 and 6 anY heavy wires thereof, showing the character loo4 g ianges 23". has relatively large or bers 22 are flared outwardly at their upper ends and terminate in the end frames 23 of angular cross section having upwardly extending ilanges 23a and inwardly directed The screen cloth shownr at 25 heavy wires 25? interwoven thereinl extending longitudinally thereof, Aand is mounted between the end frame members 23 the screen being secured thereto-by means of pairs of clamping bars 26. These clamping bars are placed on opposite sides ofthe screen cloth Aand are secured together by bolts 27 so that the bars 26 are caused to grip firmly the heavy wires 25a of the screen cloth. The lower 'bar 26 of each '(pair has a number of` longitudinally exten ing bolts 28 welded thereon, or otherwise secured thereto, and these` bolts are adapted to engage the notches 29 which are formed in the end frame members 23. The threaded extremities of the bolts 28 are engaged b nuts 30 so that a tension can be created 1n the screen cloth longitudinally of the heavy wires 25.

The screen frame 20, as illustrated in Fig. 6, is stationarily supported in screening position with the screen cloth preferably in van inclined position. The upper extremities o the end frame members 23 are longitudinally extending pins 32 'adapted to engage the brackets 33 carried by the vertical wall 34. On their lower extremities, the end frame members 23 are provided with cylindrical rejections or bosses `35 which are threade ly engaged by vertically extending adjusting members 36. These adjusting members engage plates 37 secured to the upper edge of a vertical supporting wall 38 and, by regulating the members 36, it is possible to vary the inclination of the screen frame and t e corresponding inclinations of the screen cloth carried thereby. The adjusting members 36 ane secured in adjustedv position by means of lock nuts 39. The material to be screened is delivered from a hopper 40 from which -it passes onto a rotary drum conveyor 41 and an auxiliary hoppler 42 onto the upper e e of the screen clot as illustrated at 43.

The material to be screened' passes downwardly b gravity over the inclined screen cloth, an is. subjected to the action of high fr uencev vlbrations set. up in the screen clot by means of the vibrator 45, which prefers. ly is of the type disclosed in my copending applicatiom `Serial No. 275,321,

utllizing the principle of rotating moments to produce a high frequency harmonic motion or vibration 1n planes transverse to the point substantiallyemidway of the longitu-'y axis of symmetry. f p Y The vibrator 45 is shown as mounted at a dinal frame mein r 21, the vibrator being held inv position by means of the strap 65 which extendsy around its casing and is pro- ,nstance shown is in llarly in Fig. 5. provided with.

is distributed thereby fromthreaded bars 67 are engaged by nuts 68 which may be adjusted to regulate the pressure with which the vibrator is held in position on the frame. The mounting for the vibrator 45 is preferably a single point support under its centre of gravity which in the the central part thereof. This mounti l would preferably comprise a supporting co on the, frame 20 which engages with a coacting member on the 4vibrator casing to rovide a pivotal support which, would ord substantially universal movement though limited of the casing when executing vibration. Compressed air may be used to cool this apparatus. To this end it is shown as provided witI an aperture 72 where air may be introduced and circulated through the frame 20 and thence up into the vibrator casing.

I The vibrations executed by the projecting ends of the vibrator 45 are imparted to the screen cloth by means of transmitting plates 75 which are of the form illustrated particu- These plates are provided `with apertures which are adapted to be closely fitted by the tapered extremities 76 of the vibrator casinand the plates are held in position on the v1 rator casin by means of keys 77 extending transverse y through apertures formed in the projecting end flanges 78. The upper edges of the plates 75 liave lstrips 80 ofwood, or the like, secured -thereto and ada ed to en ge the under side of the screen c oth-25. he upper edge of each plate 75 is preferably somewhat angular in contour, as shown 1n Fig. 5, and the stri s 80 are arranged at corresponding ang es to conform to the inclination of the screen cloth` which is preferably formed 'in two sections haiti different inclinations to the horizontal so t at the finely divided materials passing downwardly over the screen cloth are retarded as the lower edge of the screen is approached. The transmitting plates' 7 5, extending upwardly from the vibrator, are adapted to transmit the circular vibrations from the casing ofthe vibrator 45 to the screen cloth so that high frequency vibrations are set up in thescreen cloth in planes parallel to the paths of travel of the materials'being screened and transversely to the direction 1n which the heavy wires 25a extend. In practice, the vibrator is preferably located in such a direction thatv each particle of the screen cloth wi travel 4teiwardthe upper edge of the scr en when in the upper part of its ath of vibration. The vibrator 45 is preferably so constructed that, in operation the ends'of its-*casing execute vibrations which are substantially out of phase by 180 degrees, so that it beha/Ves sublar having a spherical surface stantially like a double conical pendulum vibrating. The vibrations are not necessarily circles, but they are harmonic vibrations having closed orbits, and a constantly changing direction of motion. With the arrangement described, each particle of the screen cloth is caused to travel in a minute closed path, as illustrated by the arrows 88 in Fig. 7 of the drawin where the longitudinal heavy wires 25u have a plurality of longitudinal fine wires 25b arranged between them. Both the heavy wires 25a and the fine wires 25" are interwoven with the transverse fine wires 25.

Instead of mounting the screen cloth in a frame, as shown in Figs. 4 and 5, the vibrator 90 maybe secured to a xed frame member 91 by means of a strap 92, as shown in Fig. 12, with the free ends of the vibrator projecting on opposite-sides of the frame and carrying the transmitting plates 93 secured thereto in the manner heretofore described. The transmitting plates 93 are engaged by the adjusting bolts 94 which are secured to clamping members 95 attached to the screen cloth 96. The screen cloth' is thus supported by the transmitting plates 93, and the bolts 94 may be adjusted to create a tension in the screen cloth if a tension is` desired.

Although I `have shown and described certain forms of the invention for purposes of illustration, it will be understood that it ma be constructed in various ways without departing from the scope of the appended claims.

I claim:

1. A Wire screen cloth adapted to be vibrated in screening machines comprising a warp and weft of relatively line wires, said ne wires being replaced-at predetermined intervals with relatlvely heavy wires having an oblong cross-section whereby a reinforced screen cloth having substantially uniform mesh throughout is provided.

2. A wire screen cloth adapted to be vi-' brated in screening machines comprising a warp and weft of relatively fine wires, said screen adapted to be supported in a state of tension and having the fine wires extending inthe direction of tension replaced at predetermined intervals with relatively heavy wires having an oblong cross-section.

3.' A wire screen cloth adapted to be vibrated in screening machines comprising a warp and weft of relatively line wires, said screen adapted to be supported from two edges longitudinally displaced and having he fine wires extending longitudinally replaced at predetermined intervals with relatively heavy wires having an oblong crosssection. A

4. A wire screen cloth adapted to be vibrated in screening machines comprising a warp and weft of relatively fine Wires, Said screen cloth having relatively large wires interwoven therein at vals and formed with a cross-section yielding substantially uniform mesh in directions transverse thereto.

5. A wire screen cloth adapted to be vibrated in screening machines comprising a warp and weft of relatively fine wires, said screen cloth having relatively large wires interwoven therein at predetermined intervals formed with approximately elliptical cross-sections. 6. A wire screen cloth adapted `to be vibrated in screening machines comprising a warp and weft of relatively fine wires, said screen cloth having relatively"large wires interwoven therein at predetermined intervals formed with approximately elliptical cross-section having its greater dimension lying in the plane of the screen cloth.

1, wire screen cloth adapted to be vibrated in screening machines comprising a warp and weft of relatively fine wires, said screen adapted to be supported in a state of tension having the fine wire extending in the direction of tension replaced at predetermined intervals with relatively heavy Wires formed with approximately elliptical crosssections and arranged to have their greater dimension lie cloth.

8. In a screening machine, the combinain the plane of the screen y tion with a vibrator, of a screen cloth reinwith interwoven relaadapted to sustain diof the received vibrations,

forced at intervals tively heavy wires rectly the stress said reinforcing altered whereby to produce a cloth of substantially uniform mesh, and means for imparting motion from said vibrator to said screen.

9. In a screening machine, the combination with a vibrator, of a screen cloth reinforced at intervals with interwoven relatively heavy wires adapted to sustain directly the stress of the received vibrations, said reinforcing wires having an'approximately elliptical cross-sectiommeans for retainngsaid screen under tension, and means for imparting motion fromsaid vibrator to said screen.

10. In a screening machine, the combination with a vibrator, of a screen cloth ,reinforced at intervals with 'interwoven relatively heavy wires adapted to sustain directly the stress of the received vibrations, said reinforcing wires having an approximately elliptical cross-section, means for stationarily supporting said screen, means for retaining said screen under tension, and 'means for imparting motion from said vibrator to said screen.

In testimony whereof, my name. f

BENJAMIN A. MITCHELL.

I have subscribed predeterminedy interv wires having a cross-section

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