US2390983A - Screen - Google Patents

Description

vK. R. BlXBY Dec. 18, 1945.

SCREEN FiledNov. so, 1942 ATTORNEY.

Patented Dec. 18, 1945 UNITED STATES OFFICE SCREEN Kenneth R. Bixby, Galesburg, "Ill.

.ApplicationlNovember 30, 1942, -Serial.No.-467,,300

'1 Claim.

Thisinvention relates to screens and similar structures, and more particularly to screens for :grading "commodities and like purposes, and to the method of making the same.

It has been -customary heretofore to manufacture screens of this type by punching the necessary openings in a plate f metal. This not only requires the use of expensive punches, which :are subject to breakage -or other injury, but also results in a large waste of meta-l, the wastage being particularly large where relatively large openings are punched in a :metal late of substantial thickness, as in a screen for grading coal. It .is necessary to space the openings substantial distances one from the other to avoid the danger of crao'kingthe intervening portions of the metal in the punching operation, or otherwise weakening the structure, and this wide spacing-decreases the open area, and therefore the capacity of the screen, and also provides the screen with relatively wide flat surfaces over which pieces of the coalor other commodity may move without passing through the-openings. The walls of the openings are substantially perpendicular to the surface of the plate and pieces :of the icommodity are apt to lodge in the openings, thus "clogging the same and interfering with the free movement of the commodity over the surface .of the screen, and when such a screen .is used for gradin a relatively soft commodity, such as fruit or vegetables, t e sharp corners are apt to injure the commodity.

One object of the invention is to provide a screen or the like which :can be manufactured without the use of metal sheetor plate stock; the manufacture of which will require much less metal than is requiredfor the manufacture of a punched screen of a similar size and character; which can be made of a lower grade of metal;

which will substantially eliminate the waste of metal in the manufacture thereof; and which will be 'of a strong rigid -.construction.

A further object ofthe invention is to provide such a screen having relatively narrow spaces between the openings therein and a correspondingly large open area,

A further object of the invention is to provide such a screen in which the walls of the openings are of such a character as to facilitate the entrance of pieces of the commodities into the same, and to materially reduce the tendency of such pieces to lodge in the openings.

A further object of the invention is to provide such a screen which can be reversed when one :side thereof has become worn, toenable the other side to 'be used.

Other objects of the invention may appear as the screen :is described in detail.

Inthe accompanying drawing Fig. v1 is a plan view, :partly broken away, of a screen embodying the invention; Fig. 2 is .a section taken on the l-ine'-2-2 of Fig. 11; Fig. 3 is a partial section taken on the line '33 of Fig. 1,; Fig. 4 is a plan view of a portion of a slightly modified form of the screen; and .Fig. 5 is a section on the line 5-5 of Fig. 4.

in the drawing I have illustrated one embodiment of my invention, together with a slight modification thereof, said embodiment being designed primarily for use in grading coal and other coarse-commodities but it will be understood that the screen may take various forms and may be used. :for various purposes without'departing from the spirit of the invention.

Large screens often comprise a plurality of :sectionsorunits and the term screen as herein used is intended to include either a complete screen or a screen section.

In the preferred form the screen comprises with the other, preferably by welding as shown at 6, to form a rigid self-supporting structure. The ring1ike elements are preferably circular in =cont'our but they may be of any suitable contour, such-as hexagonal or oval, should such contour be desirable, and the term ring is used herein .as including any such ring-like element regardless of its specific contour, The rings may ;be formed in various ways but are preferably formed of rod stock and a convenient method of making the same is to wind the rod into a tight coiland then split the coil lengthwise along one side thereof to divide the same into open rings. The :rod stock of which the rings are formed may be of any suitable cross sectional shape but *a round or substantially round vrod is usually preferable as the rings formed therefrom have :certain definite advantages, as will hereafter appear. In "assembling the rings "to form the screen they are placed side by side-on a supporting surface in sufficient number to form a structure of a length and width greatly in excess of the diameter of the individual rings and are retained in their proper relative positions durin the welding operation by any suitable means, such as pins or other plugs extending from the supporting surface into the ring and so arranged that they will not interfere with the welding operation. In the construction illustrated the rings are arranged in parallel rows with the rings of each row in staggered relation to the rings of the adjacent row or rows, so that each ring of each row, except certain end rings, extends between and i substantially in contact with the parts of two rings in each adjacent row and is substantially in contact with the adjacent rings in the same row, thus spacing the ring openings relatively short distance one from the other and avoidin wide fiat surfaces between the openings. If desired, the spaces at the ends of the shorter intermediate rows may be filled with half rings welded to the adjacent rings, as shown at 1. It is preferable to place the open side of each ring adjacent the closed portion of another 7 ring and to weld the same thereto so that the weld will rigidly connect the ends of the one ring as well as connect the two rings one to the other. 7 The welding of the rings may be effected in any suitable manner, as by arc welding or resistance welding, arc welding having been employed in the screen shown in Figs. 1, 2 and 3. The screen is self-supporting but to facilitate the mounting of the same in working position it is usually provided with a frame extending about the same and connected with the outer series of rings at the edges of the structure. The connection. between the frame and the structure formed of the rings may be of any suitable character and in the arrangement illustrated I have employed a flat rectangular frame 8 to which the outer rings are welded. While the screen is here shown as flat it will be obvious that it may takeother shapes, such as curved or cylindrical.

In Figs. 4 and 5 there is shown a portion of a screen of slightly modified construction, the contacting portions of adjacent rings being embedded one in the other and fused together. This results in decreasing the distances between the centers of adjacent rings and thereby reduces the size of the spaces between the rings and thus increases the aggregate area of the screen openings with relation to the total area of the screen. This type of connection is preferably effected by flash welding, which is a resistance butt welding process wherein the weldin heat is developed by the passage of current in the form of an arc across a short gap between the surfaces to be welded, these surfaces being kept slightly separated until they have flashed off to parallelism and have reached the desired temperature. The electrical circuit is then opened and an upsetting movement takes place to unite the fused parts, The heat and pressure are so controlled that upon each welding operation the welded portions of the rings would be embedded one in the other the same distance so as to maintain the rings in predetermined relative positions to produce a uniform screen. This result may be facilitated, and the construction of the screen expedited, by simultaneously welding each ring to two or more other rings.

As will be apparent from the drawing and the foregoing description my screen requires no metal sheet or plate stock for its construction; the quantity of metal is very much les than would be required for a punched screen, in some cases as much as seventy-five percent less; and there is practically no waste of metal in building the screen. Further, the rings may be made of a. relatively inexpensive grade of steel such as rerolled stock; and punches are not required thus avoiding the use of expensive high grade tool steel. These advantages are of material importance at any time but they are especially important at the present time when metal of any kind is difficult to obtain and plate stock of the kind required for the punched screen and tool steel as required for punches are not to be had without a high priority rating.

The rigid connections between the rings produces a rigid plate-like structure which is self supporting and has ample strength for its intended purpose, that is to support the material being screened without objectionable sagging.

The ring stock being of relatively small thickness or diameter and adjacent rings being in contact or substantially in contact one with the 'other' it follows that the spaces between the openings of adjacent rings are relatively narrow and consequently the open area of the screen is relatively large. The narrow spacing of the ring openings also reduces the size of the triangular openings between adjacent rings and the area of the flat metal surfaces between the openings and thereby reduces the tendency of the pieces of the commodity to slide along such flat surfaces without entering the openings. Ring stock of round or hexagonal cross section provides the openings with flared ends which further reduce the width of the flat surfaces and permit the pieces of the commodity to tilt and more readily enter the openings. Thus practically all pieces of the commodity which are of a size not greater than the diameter Of the openings will pass through the openings and the efliciency of the screen is correspondingly increased. Due to the rounded orbeveled ends of the walls of the openings a piece of the commodity which tends to lodge in an opening canQhave a. limited tilting movement therein and the contact of other pieces of the commodity therewith will work it loose and cause it to pass through the opening. The two sides. of the screen being identical either side may be placed uppermost and when one side is worn away so as to adversely affect the screening operation the screen may be reversed to place the other side uppermost.

While I have shown and described one embodiment of my invention I wish it to be understood that I do not desire to be limited to the details thereof as various modifications may occur to a person skilled in the art.

Having now fully described my invention, what I claim as new and desire to secure by Letters Patent is: V

A commodity separating screen comprising a plurality of preformed rings arranged in edge to edge contact to form a structure of a length and breadth greatly in excess of the diameter of the individual rings, the'contacting portions of adjacent rings being embedded one in the other and fused together to form a rigid platelike structure in which the spaces between the openings in adjacent rings are relatively small.

- KENNETH R. BIXBY.

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