US2014128A - Vibrating screen - Google Patents

Description

Sept. 10, 1935. E. IQDEISTER EIAL 2 Sheets-Sheet l /y/aey gw E E 1751525? E 75525? Filed May 14, 1931 Patented Sept. 10, 1935 UNITE D STAT E S PATENT OF F ICE.

VIBRATING SCREEN Application May 14, 1931, Serial No. 537,287

1 Claim. (Cl. 209-382) This invention pertains to vibrating screens and more: particularlyto means for imparting a sharp vibration tothe screening medium, distinct from its vibratory-movement;

5 In the present conventional vibrating screens considerable difficulty has been encountered in screening fine-material, eitherwet or dry, and also coarser material, where the same is of a sticky or gummy nature. Numerous. attempts have been made-to overcome the'foregoing difficulties, and while these have met with some degree of success, they fail to completely solve the problem, and have also developed other'serious objections,

In-certain" types of screens, the'screening medium receives a hammer-like vibratory movement from an electro-magnetic actuated mechanism connected to the screening medium. This principle failed'forseveral reasons, inthat'it"is expensive, and the strikeractioniis only effectively transmitted to the screen for an exceedingly limited distance.

Also, in devicesxof theforegoing character, it is necessary to subject'the' screening medium to excessive" tension in order'to obtain any appre ciable transmission of" the tapping action, and this is objectionable in that strain' upon the screening medium quickly'fatigues and stretches the'wires; materially reducing the useful'lifeof the screening medium.

Others: have employed a" cam mechanism for producing a hammer-like vibratory'movement' to the screening medium, but this also meets the foregoing objections.

" Still anothermethodcomprises the attachment of a strip to the screening mediumfor. engaging a'rigid member carried by theiframe. However, this has proven objectionable, as excessive amplitude of the vibratory movement would be nec- 40 essary in order to obtain the required impact between the strip and the stationary member.

Furthermore, it will be appreciated that the vibratory strip must be held in control by'the fine screen cloth, and. therefore the wires soon become fatigued, and weakened, and because of the excessivevibratory movement required, soon crystallize:

Otherobje'ctions reside in" the fact that it is commercially impractical to maintain a sufficient tension on the screening medium, so that the strip willuniformly engage the rigid member throughoutits entire length. In otherwords, if the screen cloth is stretched too tight atone end, the tapping action is prevented at that point,

5 whereas if-lefttooloose,- excessive whipping will result. Furthermore, action of the strip can only be controlled or limited through the tension created upon'thescreen cloth, and when the same is properly adjusted; for light or no load,such adjustment'will be incorrect for heavier material 5 loads.

It is, therefore primarily the object of the present invention to overcome the foregoing-objections by the provision of simple, inexpensive, and efiicient meansfor imparting a sharp vibration to 10 the screeningmedium of a'vibrating screen, distinct from its vibratory movement, and uniform- 1y impartinga positive controlledtapping action to the entire screen. surface without damage thereto. 15

Incidental to' the foregoing, a more specific object resides in the provision ofa plurality of hammers or'istrikers actuated-solely through the vibratory movement of the screen, and adapted to engage" vibratory means associated with a screening'medium, thus eliminating the necessity of excessive stretchingand amplified'vibratory movement; together with mutilation and wear of thescreeningm'edium, at the same time providing a sharp; positive tapping action over the entire 25 surface of the screening medium, independent'of load" or 'ten'sion' upon! the screeningmedium.

A still further object resides in so mounting the hammers that in operation they serve to neutraliz'e'theaction of each'other', thus eliminating 30 twisting or'strain' on their support;

.With'the above and other objects in view, which will appear" as thedescription proceeds, the invention residesin the novel construction, combination, andiarran'gement of parts substantially 35 as" hereinafter described and more'particularly defined by'theappended'claim, it being understood that such changes in the precise embodiment of the herein disclosed invention. may be made as come within the scope of the claim. 40

In the accompanyingdrawings is illustrated onecomplete. example of the physical embodiment of th'e'present inventionconstructedaccording to the best mode so far devised-for the 1 practical application of the principlesthereofi 45 In the drawings, Figure lis'a longitudinal section through a conventional'type of vibrating screen'emb'odyin'g one form of 'the present invention;

Figure 2 is a transverse section takenon the 50 line 2"2"ofFigure l;

Figure'3'is a detailed bottom plan view of one o-f'the screen panels with theinventionappli'ed thereto; and

Figure' l'is an'elevation of a'screen panel'ill'ustrating a modified form of the invention attached thereto, parts being broken away and in section to more clearly illustrate the structural details.

Before taking up in detail the description and explanation of the accompanying drawings, it is to be understood that the present invention is applicable to any and all types of vibrating screens, regardless of structure or the manner in which the screens are actuated, the present invention residing in the provision of means for imparting a sharp vibration to the screening medium per se, distinct from its vibratory action.

Furthermore, while the invention has been illustrated as applied to removable screen panels, such as are in common use at the present time, it is understood that the same is just as applicable to any screening medium, irrespective of the manner of attaching the same to the frame.

Merely for the purpose of illustrating one application of the invention, that general type of vibrating screen as disclosed in pending application filed February 24, 1931, Serial No. 517,730, has been shown. However, the invention is applicable to vibrating screens actuated by hammers, unbalanced shafts, eccentrics, or other mechanical means.

Considering the preferred form of the present invention, as illustrated in Figures 1 to 3 inclusive, the numeral I designates a base adapted to be supported upon any suitable foundation at approximately the angle desired. Mounted on the base are the spring seats 2 for reception of the coil springs 3, which in turn support the spring seats l secured to the side frames 5 of the vibrating screen section. Intermediate the ends of the side frames 5, the same are connected by the transverse irons 6, which carry the vibrating mechanism I of the overbalanced type, as disclosed in the aforesaid application, while the ends of the side frames are connected by the transverse angle brace 6'.

Longitudinally secured to the inner faces of the side frame 5 are the supporting angles 8, which in the present instance receive a pair of screen panels 9, the latter being securely clamped on the supporting angles by means of the straps II engaging the sides of the panels and drawn into clamping engagement therewith by means of the bolts I I passing through the side frames 5.

For convenience of manufacture, the screening medium illustrated is formed in two sections or panels. However, as heretofore explained, the same may be constructed in one piece and secured to the side frames in any suitable manner. Each panel 9 comprises a rigid channel frame I2 upon which a screen cloth I3 is secured by means of straps I4 bolted or otherwise secured to the channel frames I2.

In applying the present invention to the type of screen illustrated, one or more longitudinal vibrating strips I5 are provided, which may be secured to the angle irons I6 by welding or other suitable means, and in turn the angle irons I6 are bolted or secured to the channel frames I2 to bring the vibrating strips into engagement with the bottom surface of the screening medium I3, thus serving to normally support the same and eliminate strain thereon, as the result of loading, and avoiding the necessity of tautly fastening the screening medium to the channel frame.

In the preferred form of the invention illustrated, the vibrating strips are shown as attached longitudinally to the screen panels 9. However, it is to be understood that the same may be ap- In the preferred form illustrated, the transverse support I1 is secured to the channel frame of each panel by means of the brackets I8, or other suit-' able provision, and is preferably positioned centrally of the ends of each screen panel in order that the strikers hereinafter referred to may be distributed with relation to the screening element to provide for uniform auxiliary vibration to the screening medium over its entire surface.

Suitably secured to the supports II are a plurality of strikers or hammers I9, each comprising a resilient arm 20 having secured to its outer free end a weighted head 2|, which upon actuation engages the vibrating strips I5. In order to prevent mutilation or wear of the vibrating strips by engagement of the strikers, the strips have welded or secured to the bottom face thereof striker plates 22, although it will be appreciated that these may be eliminated without affecting the principle of the invention. While in the drawings the weighted heads 2I of the strikers are shown normally engaged with the striker plates 22, it is to be understood that a slight clearance may be provided, if desired, for effecting the hammer action of the strikers.

While it is not essential to the operation of the 40 Referring to the modification illustrated in Figure 4 of the drawings, it will be noted that the supports I! have been eliminated, in which structure the hammers or strikers I9 are bolted or secured directly to the vibrating strips, and while such structure will function to produce the desired results, particularly in small-sized screens, the preferred embodiment of the invention as heretofore described presents certain advantages, in that the striking action of the hammers is entirely free, and in no way affected by any whip or yield in the vibrating strips I5, which might occur in the structure shown in Figure 4, particularly in a large-sized screen.

Taking up the operation of the invention, it is believed that the same will be quite apparent to those skilled in the art, in that as vibratory movement is imparted to the main frame of the screen through any suitable vibrating mechanism such as indicated at I, the inertia of the weighted strikers I 9 will cause the same to produce a sharp positive hammer action against the vibrating strips I5, which in turn is transmitted to the screening medium I3 engaged by said strips, it being appreciated that the tapping action of the hammers is entirely distinct from the vibratory movement of the screen. The foregoing sharp tapping action of the strikers effectively eliminates the tendency of fine or sticky material to blind or clog the screening medium, and in view of the distributed position of the strikers, the sharp vibrations are transmitted substantially uniformly over the entire surface of the screening medium.

It will be noted in the preferred form of the invention that the strikers H! are secured to the support I! in opposed relation, and therefore inasmuch as movement is simultaneously imparted to the opposed strikers they serve to neutralize each other and avoid twisting strain on the supports.

The operation of the modified form of the invention illustrated in Figure 4 is for all practical purposes the same as that of the preferred form, in that vibratory movement of the screen will impart action to the hammers l9, due to their inertia, causing the same to impart a tapping action upon the vibrating strips l5, which in turn is transmitted to the screening medium.

In all instances, it will be noted that the present invention is distinguished from other forms and types of auxiliary vibrating mechanisms, in that additional means is not required for actuating the hammers or strikers, they being actuated as the result of the vibratory movement of the screen, resulting from the action of the primary vibrating mechanism.

From the foregoing explanation taken in connection with the accompanying drawings, it will be readily seen that comparatively simple and highly efiicient means has been provided for eliminating blinding of the screening medium in vibratory screens, by either extremely fine or sticky material, the screening medium being freed from the material by the sharp, positive tapping action of the hammers, during the vibratory movement of the screen, and while a specific arrangement of vibrating strips and. hammers has been illustrated and described, it is to be understood that this may be varied in numerous ways, it being the purpose of the invention to so arrange the hammers and vibrating strips as to obtain a substantially equal distribution of the tapping action over the entire surface of the screen.

In addition to the highly novel and efficient operation of the present invention, particular 5 attention is again directed to the advantages resulting from the structural features, in that the necessity of a taut or drum-tight screening me-' dium is eliminated, and in addition thereto the vibrating strips serve to support the screening medium for heavy loads, thus relieving strain thereon and materially increasing the useful life of the screening medium. Also, the tapping mechanism is such that the strikers or auxiliary vibrating means does not act directly upon the screen, thus avoiding damage and mutilation of the same.

While the strikers or hammers I9 have been illustrated and described as comprising weighted resilient arms, it is contemplated that other structures may be employed, it being merely essential that the hammers have free controlled movement with relation to the vibratory movement of the screen.

We claim:

In a vibrating screen including a vertical vibrating frame and a screening medium carried thereby, a vibrating member carried by said frame and engaged with said screening medium,

a support carried by said frame and positioned below said screening medium, and a pair of opposed strikers carried by said support and vertically actuated by vibratory movement of said frame to produce a tapping action on said vibrating member.

EMIL DEISTER.

EMIL EDWARD DEISTER.

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