US1983676A - Method of and apparatus for screening - Google Patents

Description

D33. M. P. REYNOLDS ET AL 1,983,676

METHOD OF AND 'APPARATUS FOR SCREENING Filed Dec.,8, 1931 2 Sheets-Sheet 2 I N VEN TOR 5 War/l3! Each fig vaidhid wiiace cli /9'70 ATTORNE 6;

Patented Dec. 11, 1934 INITED STATES.

METHOD OF AND APPARATUS FOR SCREENING Morley Punshon Reynolds, Cleveland Heights, and Wallace J. Piggott, East Cleveland, Ohio, assignors to The W. 8. Tyler Company, Cleveland, @1110, a corporation of Ohio Application December a, 1931, Serial No. 579,724

2 Claims.

The present invention, relating. as indicated, to

a method of and apparatus for screening materials, is more particularly directed to a new and improved method of screening or classifying both fine and coarse bulk materials and to an apparatus particularly adapted for economic, rapid and accurate separation of this type of material by size. The principal object of the invention is the provision of a method of and apparatus for handling bulk materials which will be extremely eflicient in operation, capable of high tonnage capacity, extremely accurate, capable of operating with a low angle of screen surface, adaptable to give various motions and vibrations to the screen and uniform in its adaptability to various sizes'of material. A further object of the invention is the provision of a method of and apparatus for the purpose described which will be low in initial cost and economical in the foregoing and related ends, said invention, then, consists of the means hereinafter fully described and particularly pointed out in the claims.

' The annexed drawings and the following description set forth in detail certain means and one mode of carrying out the invention, such disclosed means and mode illustrating, however, but one of various ways in which the principle of the invention may be used.

In said annexed drawings:

Fig. 1 is a side view partially in section of a screening apparatus embodying my improved apparatus, and capable of carrying out the'steps of my new and improved method; Fig. 2 is a plan view of such apparatus; Fig. 3 is a transverse sectional view of theapparatus illustrated in Fig.

2, taken on a plane substantially indicated by the line 3-3; Fig. 4 is a side elevational view,

partially in section, of an apparatus similar to Fig. 1, but showing an alternative form of construction; Fig. 5 is a fragmentary sectional view drawn to an, enlarged scale of a modified form of a portion of the apparatus illustrated in the previous figures; and Figs. 6 and 7 are fragmentary part-sectional, part-elevational views showing further modifications.

Screens now in general commercial use fall into a few well defined classes. On'such screens,

the electro-magnetically vibrated woven wire screen is the most efficient and is the most widely used for the screening of all relatively fine materials and is extremely efiicient and economical in operation in this field. For the screening of heavy materials, mechanism employing either 5 5 tensioned woven wire screens which are vibrated use of power, etc. To the accomplishment ofthe and are high in their cost of maintenance, but

are in fairly common use for the classifying of heavy and coarse materials.

' The present invention has been designed to provide a methodand an apparatus for relatively universal use and one which may be employed for screening both fine and coarse materials with a minimum consumption of power and a minimum of upkeep, and with an effective vibration of the screen surface, which is uniform throughout its entire area and suficient in amplitude and intensity to effectively screen the coarse as well as the fine materials.

Referring now to Fig. 1, we have shown a side view, partially in section, of an inclined screen, the apparatus'consisting of a box-like casing l pivotally mounted upon a suitable support 2 and adjustable with respect to-its angle to the horizontal by any suitable means, not shown. With in this casing there is mounted the usual woven wire screen and as so far described, the apparatus employed is relatively standard.

The principal difficulty in the adaptation of the electro-magnetically vibrated screen to coarse materials is in securing a sufiicient amplitude and intensity of vibration, and, while this can be secured, it requires the use of extremely heavy, powerful electro-magnets, the size of which has to be increased out of all proportion to the remainder of the apparatus. A further limitation in the use of electro-magnetic vibrating apparatus heretofore in use has been that, while efiective to secure a suflicient amplitude in the central portion of the screen, this movement of the screensuriace diminishes toward the edges of the screen, which are therefore not in a state or vibration permitting them to efiectively screen material or to prevent clogging and blinding, particularly with certain types of material which it is desired to screen.

Our new and improved screening method consists in passing a layer of screenable bulk material over an inclined woven wire screen which is tensioned to a. vibratory tension throughout its entire screen surface, but which is floated and resilan effective use of the entire area of the screen and thus impart to the screen a relatively rapid,

cure the ready tron of this vibration throughout the screen surface. In Figs 1, 2 and v3, we have shownone form of apparatus which embodies our inventionand which is capable of carrying out thesteps of the method stated -'above.

- nevertheless itis to be understood that any suitable number depending upon the type and size of screen cloth may be employed for the purpose of vibrating such cloth. The electro-magnetic vibrators 5 have their armatures secured to U-shaped brackets 6 which, in turn, are secured to a strip or plate engaged with the woven wire screen 4.

Mounted on the parallel side members 2 and 3 are a series of studs 8 extending at right angles to the longitudinal axis of the frame and the screen, and carrying at their ends hook members 9, abutment portions of which are adapted to be engaged by the rebent hook-shaped strips 10 to which the screen may be secured. The studs 8 at their outer ends carry seat members 11 and nuts 12, and compression springs'13 are interposed between the seat members and the side frame members 2 and 3 to permit of the application of any desired lateral tension to the screen. The studs 8 are not fixed in the frame members 2 and 3, but are movably mounted therein and pass through openings larger than the studs, permitting angular movement by the studs as required.

In order to insure against the passage of unclassified material between the edge of the screen and the inner faces of the side frame members 2 and 3, baille members is are provided which are preferably of suitable resilient material and are supported from such side frame members 2 and 3 by angle brackets 15.

As previously indicated, the number of vibrators employed may be varied to suit the particular requirements of the cloth being operated upon, as well as the material which is to be screened. Three arm-senators may be employed, or any desired number to produce the desired results.

, In Fig. 4 are shown vibrators 5a, mounted at an angle to the screen surface and secured through angle brackets 15 to the screen strip. In this construction the screen is not vibrated in a straight up-and-down plane at right angles to the normal surface of the screen cloth, but in a plane at" acute angles to the normal screen surface, giving the screen a vibration having components both longitudinally and at right-angles to its surface, thus securing a motion of the screen surface which may be employed depending upon the angle and inclination of the vibrators to either hasten the flow over the screen, or to retard such flow.

As the movement of the material .can in this way be hastened, it is possible to. operate the screen at a lower angle than in ordinary types of screening apparatus, which will not only require intense vibration at points most eflective to seless head room for the apparatus, but which will maintain the material in contact with the screen for a greater period, and thus more accurately separate the material by size as it will prevent rapid rolling or bouncing of the material over the screen. In Fig. 6 is illustrated a modified form on con.- struction for engaging and supporting the sides of the screen cloth by the studs which carry the compression springs. As illustrated in this fits ure, the stud-16 is provided with a hook-shaped terminal 1'7 which engages around either one of the wires of the screen cloth, or a slightly larger rod 18 which may be welded to the body of the cloth or woven therein. The studs 16 likewise pass through enlarged apertures 19 provided therefor in the side frame members 2 or 3, and

terminally carry a nut 20 and seat member 21 by means of which the compression of the spring 22 can be regulated and, accordingly, the amount of the tension imparted thereby to the screen may be accurately adjusted.

In Fig. 5 is illustrated a further modification of the means for supporting the screen cloth which may briefly be described as follows: Two screen cloths 23 and 24 respectively, are superimposed' one above the other and the mesh of the former. will preferably be larger than the mesh of the latter, which determines the fineness of the material which will be classified. The upper screen cloth 24 is supported on the lower by means of strips 25 which have certain forms of construction made of suitable resilient material, such as rubber, and for other forms of. construction materials such as asbestos, wood, and the like, may

be employed.

The lower cloth 23 is supported and tensioned by apparatus similar to that employed for the purpose of supportingthe screen cloth in Fig. 3. Hence, like reference characters having prime marks will beemployed for the purpose of designating like parts in this figure, and a further description of this apparatus will not be given.

The upper screen cloth 24 is supported and tensloned by means of a bracket member 26 which has an abutment 2'7 engaging the hook strip along the edge of the cloth and has a heel portion 28 bearing against the inner surface of the side frame member 2. The angle bracket 26, and accordingly the screen cloth 24 supported thereby, is

cloth with a very much heavier and coarser cloth,

and in this way securing a much sharper and more intense vibration of the lighter cloth with-' out the wear which is usually incident to contact between two such woven wire screens. In the past, light screens have frequently been supported by heavier screens, but the relative'movement between the two screens rapidly wears the light screen and necessitates frequent replacement.

In Fig. 'I is illustrated a diflerent form of construction for resiliently supporting the screen cloth, so that the screen-is supported in freely vibratory condition throughout its entire area, such means comprising bracket members, gener-' ally indicated at-8l, an angularly moves about its fulcrum abutment 32 arranged for engagement by the hook strip along the edge of the screen cloth, an upwardly extending portion 33 providing an abutment for securing a packing strip 34.

The bracket, generally indicated at 31, is rigidly secured to a flexible stud 35, which, at its outer end 36, is adjustably rigidly supported in a saddle 37 provided therefor, such saddle being mounted on, and carried by the side frame members 2 or 3.

This modified construction, it will be noted, permits the screen supported and tensioned thereby to freely oscillate or vibrate over its entire area, due to the resilient characteristics of the studs 35 supporting thecloth. Any number of such studs may be employed, depending upon the character of the cloth supported thereby, as well as the characteristics of the material to be treated. The studs 35 pass through enlarged apertures in the side frame members so that the only point at which they are arrested is at their points of support on the saddle 3'2.

The present invention presents many advantages over the prior methods of'screening. Our new method permits the screen surface to be effectively. vibrated throughout its entire area and to be vibrated in such a way as to give an angular impulse to the screen instead of an impulse at right angles to the normal plane of the screen surface. An additional advantage is that the free floating of the edges of the screen permit the entire screen surface to be vibrated and remove the tendencyto cramp the armature and hence, to allow the electro-magnet to assume its full normal stroke, and to impart this strokeun- Y diminished to the screen where the movement is fact that the electro-magnetic method and means of vibration, which is admittedly the most eflective for the screening of fine materials can, by our improved method, be employed for the screen-- ing of both fine and coarse materials with greatly improved results in the screening of coarse materials and with advantages in both tonnage and separation in the screening of fine materials.

Other modes of applying the principle of our invention may be employed instead of the one explained, change being made as regards the means and the steps herein disclosed, provided those stated by any of the following claims or their equivalent be employed.

We therefore particularly point out and distinctly claim as our invention:

1. An apparatus of the character described, the combination of a frame including spaced sidemembers, spaced woven wire screens disposed betweensaid side members, means for fioatingiy supporting one of said screens to maintain the whereby vibration is imparted to the otherthrough said supporting means.

2. An apparatus of the character described, the

combination of a frame including spaced side members; spaced woven wire screens disposed between said side members, the lower of said screens of larger mesh and stronger wires; means for floatingly supporting said. lower screen to maintain the same in freely vibratory condition throughout its entire area; means for supporting the upper screen on the lower; and means for imparting vibration to said lower screen whereby vibration is imparted to the upper screen through said supporting means.

. MORLEY PUNSHON REYNOLDS.

WALLACE J. PIGGOTI.

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