US2211000A - Screening apparatus - Google Patents

Description

Aug. 13, 1940. H. E. BROWN er AL SCREENING APPARATUS Filed April l, 1936 INVENTORS Patented Aug. 13, 1940 SCREENING APPARATUS Hugh E. Brown, cleveland Heights, and stewart Grant, Cleveland, Ohio, assignors to The W. S. Tyler Company, Cleveland, Ohio, a corporation of Ohio A .Application April 1, 1936, serial No. '72,076

2 Claims.

' The present invention, relating as indicated to screening apparatus, is directed more particularly to apparatus for the screening of bulk materials. j The principal object of the invention is the provision .of a screening apparatus in which" the weight of the screen and the load passing thereover do not rest upon, and therefore do not affect, the vibrating means and thefreedom of movement thereof.r l Other objects of the invention are 'the 1 i provision of a screening-apparatus'and means for electro-magnetically .vibrating the same in which the vibrating means may be initially designed and adjusted during manufacture to the particular screen without the necessity for subsequent if adjustment in the field. Other objects of the inventiqn will appear hereinafter. Y

',To the accomplishment of the foregoing and relatedends, said invention, then,f consists of the means hereinafter fully described and particu- 2 larly pointed out in the claims; the annexed drawing and the following description setting forth in detail certain means of carrying out the invention, such disclosed means illustrating, however, but one ofthe various ways in which the principle of the invention may be used.

. In said annexed drawing:

Fig. 1 is a side elevation of our improved screening apparatus mounted in an inclined position;

` Fig. 2 is an enlarged side elevation of the frame,

screen andvibrating mechanism therefor;

Fig. 3 is an end elevation partially in section showing the resilient. means for mounting the movable screen-,carrying frame; and Fig. 4 is a partial transverse section showing a two-deck screen.

Fig. 5 is an enlarged portionof Fig. 2 showing the electro-magnetic vibrating structure in detall.

In the screening of coarse material ithasalways been found extremely difficult to secure continuous and effective action and to construct a machine capa e of screening various sizes of material and varying loads of material even though adjustments were incorporated in the machine which made it possible to vary the intensity and amplitude of movement imparted to the screen in order to accommodate this movement to the material. This has been true of all types of screening apparatus operated on coarse materials,

but has been particularly true of electro-magnetically operated screening apparatus, in which either the screen or screen-carrying frame was vibrated at an angle to the plane of material passing thereover by'electro-magnetc means. In

this latter construction the load of material on the screen necessarily changed the gap. between the armature and the field of the-electro-magnetic means and this required constant adj-ustments which were secured by resilient means in- 5 corporated in the electro-magnetic means. The adjustment of the resilient means to cause greater or less tension between the armature and field ed by the load on the screen-carrying frame. In

this way we have found that it is possible to initially proportion the electro-magnetic apparatus' to the screen and screen frame and the 20 mounting therefor, adjust or set these during manufacture, and thereby render the apparatus continuously proportioned and adjusted to secure the action required regardless of the size or weight of material passing over the screen. 25

Referring now to Fig. 1 of the drawing, our improved screening apparatus consists of a frame orvbase I mounted in an inclined position upon supports 2 and 3, which in turn may either be supported from overhead or mounted upon the floor 4. Resiliently mounted upon the fixed frame I is a movable frame adapted to carry the screen cloth, as will presently be explained, which consists of spaced parallel angular members I0 provided with exteriorly extending plates or brackets il and secured together by means of transverse members I2. The exteriorly extending brackets II on the screen-carrying frame IU are mounted between coil springs I3 and I4, a pair of which are disposed adjacent either end of the screen-carrying frame, the lower springs being in turn mount- Q ed upon the rigid frame I and the upper springs being mounted between the brackets II and an adjustable washer I4', the position of which may be adjusted and fixed by means of a nut I5 engaged upon a stud I6 extending from the rigid frame through the centers of the coil springs and above the same.

The screen-carrying frame I0 may be provided with one or more decks or screens which may be remably secured therein in various ways. As here shown, the frame is provided with two screens 20 and 2l arranged in spaced parallel relation, each screen being provided with a bent or curled edge portion 22 engaged by a anged edge 55 ment. It will be seen from the description up to this point that` our apparatus includes a rigid sub-frame and a freely, resiliently mounted screen-carrying frame supported thereon by -means of "opposing springs which place the screenfcarrying frame in condition for free floating movement in a plane at right langles to the plane lof the rigid frame. A

'I'he screen-carrying frame I0 is vibrated by an electro-magnetic device consistingfof a coil 30 fixed to the side of the frame'i and a oating armature 3l in the form of a plate with ends projecting beyond the coil 30, wherethey are mounted between opposed pairs of springs 32. A pair of cooperative striking blocksy are mounted on either side of the field, one bl'ocl: 33 being se- `cured to the frame and the other block 3d being secured to the armature. 'We employ preferably four electro-magnetic devices, mounting two on either side of the frame, each being approximately one-fifth or one-fourth of the total.

tionof all parts of the screen surface if the electro-magnets are mounted as stated. The best screening effect is secured when the screen accelerated downward away ,from its load so that the screen and load part company on the downward-motion ofthe Screen, as this -allows the screen to clear itself, jolting out any pieces of material which have stuck in the' mesh of the screen and allowing all of the material on the screen to shift its position before'again being contacted by the screen on the'upwardmovement of the latter. It is also desirable in'securing the best results to-provide rapid upward acceleration of the screen and, to some extent, it is immate-f rial whether the electro-magnetic devices'employed operate to pull the screen away from the,

and the form of the motion given to the screenu dependupon the frequency and type of current supply to the electro-magnet, the. stiffness of the springs effecting the return movement of the armatureand the armature weight. The action ofthe screen will depend upon the'factors named above and-upon the proper proportions of the weight of theA armature, the'vibrator springs and the pull of the electro-magnet, together with the natural period of vibration of the springs, sup-- porting both the screen-carrying frame and the armature, all of which can be properly determined, built and adjusted when the apparatus is manufactured. Therefore no adjustment is necessary, since the load on the. screen merely deiiects the springs I3 and Mfwithout in any way changing the position of the armature or the relation between the armature and the frame.

In operation, the armature is resiliently pulled toward the magnet, all of the armatures being vfirst designed.

simultaneously operated in the same "direction, that is, in the apparatus shown, downward The armatures are pulled downward until the cooperative striking blocks and 34 engage when the screen is given a sharp jar and the armature is then immediately returned to its original posi- .tion by means of the compressed lower springs of the pair ofsprings Y32, when the cycle" isrepeated. The armatures can be provided with weights 35 when the machine is/built, adjusted with vrespect to the otherparts of the structure so as to give .the best results and, -since `these weights are a ypermanent part ofthe electro-magnetic means. `theyf, cannot be tampered with in the field to modify the action for which the mahine was We have found that very satisfactory screen-y. ing results are secured in an apparatus embodying our invention in which the screen-carrying4 frame, plus the screenswith the weight of approximately [1,450 pounds, was supported on springs interposed between that frame and the rigid framewhere the combined resistance of the; interposed Vsprings was approximately 11,500 inch pounds. With such a natural vibration frequency for the suspension of the screen, and with a frequency of 30 cycles per second atwhich the armature operated, `very good results were secured. In this same .construction 'the natural l frequency of the armature, by reason vof the resilient support therefor, was approximately 42 cycles per second, which corresponds relatively closely to the natural frequency of the supporting v springs for the frame of 45 cycles per second.

Other modes of applying the principle'of our invention may be' employed instead ofy the one explained, change being made as regards the mechanism herein disclosed, provided the means.

statedfby any of the following claims or the `equivalent of such stated means be employed.

We thereforeparticularly point out and distinctly claim as our invention:

1. In a'screening apparatus, `the combination of I a base, ascreen frame supported on said base, resilient means interposed betweensaidframe and base, means associated with said resilient means to confine movement of said frame to a plane substantially. at. right angles to the base, a vibrating means comprising an electromagnet fixed to said frame and immovable relative thereto, and an armature iioatingly supported by said frame, opposed resilient means engaging opposite' sides of said armature for providing said iioating support for the armature, said armature being movable in a direction at right anglesto the plane of the screen, under the -iniiuence of said electromagnet, a stop carried by said armature, and a cooperating stop on the frame so positioned that movement of the armature due to said magnet causes engagement of the stops to abruptlyarrest movement of the armature.

2. In a screening apparatus, the combination of a base, a screen frame supported on said base, resilient means mounting saidframe on said base, said means including upper and lower resilient members between which is interposed a portionY of the frame, and a stud on said base connecting the upper and lowerv portions of said'members, means on said stud for varying thevcompression of the resilient means, a vibrating means comprising an electromagnet fixed to said frame and immovable relative thereto, and an armature oatingly supported by said frame, opposed re' silie'nt means engaging, opposite sides of said armature for providing said floating support for the armature, said armature being movable. in a direction at right angles to the plane of the screen, undef the inuence of said electromagnet, a stop carried by said armature, and a cooperating stop on the frame so positioned that movement of the larmature due so said magnet asus-es engagement of the stops to abruptly arrest movement of the armature.

EUGH BROWN. STEWART GRANT.

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