US2001631A - Sieve liner - Google Patents

Description

May 14, 1935. H. B. RICE 2,001,631

SIEVE LINER Filed Sept. 19, 1933 Patented May 14, 1935 SIEVE LINER Harry B. Rice, Houston, Tex., assignor to Vacuum Belting Cloth Cleaner Corporation, Houston, Tex., a corporation of Delaware i Application September 19, 1933, Serial No. 690,140

' 4 Claims.

My invention relates to liners for sieves or.

sifting screens and particularly to liners for devices of this character which are commonly used for sifting or screening fine materials such '5 as flour, talcum powder and tooth paste.

Bolting or sifting screens employed for such purposes, and particularly those which operate- With a vibratory or gyratory motion, are generally provided with screen cloths .of silk or other thin fabric,- stretched upon and secured to an open frame or grate. This supporting frame is usually constructed of wooden strips, bars orsections nailed or otherwise secured together, the area within the frame being divided into compartments by cross bars, strips or partitions. Upon the inner surfaces of the frame so formed and partitioned marginal liners are customarily secured by nails or other suitable fastening means. The sieve liners heretofore known and 1.9-. used have been made of fabric strips or of wooden sections. Liners of either of these types, being of a more or less porous nature, absorb a certain amount of-moistureand cause particles of the substances being screened to adhere to and remain upon them; Particles of the material being sifted become lodged in the angular corners of the liners upon the frame and in the crevices of the joints between adjacent liner sections. These liners are also objectionable because they wear out rapidly and have to be replaced frequently.

Liners formed of'metal strips or plates secured together would be little, if any, more satisfactory than the objectionable wooden or fabric liners.

same angular corners and crevices for catching particles of material, as are present in the Wooden line'rsr The increased weight and cost of the metal frames would also be undesirable. Moreover, unless they were formed of some special expensive metal they would be liable to rust and deposit particles of rust or scale in the screened materials.

These objections and defects areespecially important and-serious in the case of screens ,or sieves used for screening food materials (for example, flour or salt) or toilet or pharmaceutical powders or preparations (for example, talcum powder, tooth powder, tooth paste and soda). In the screening of materials of this general character it is not only important, but vitally essential, that the cleanliness and purity of the screened material be preserved. Caking of particles of the material upon the frame or liner or in corners or crevices, and/or the introduction of such old and stale caked particles or fragments of dirt, rust or other foreign matter, results in an impure and otherwise unsatisfactory screened product.- 7

. The marginal inner liners heretofore provided Such metal liners would have the are otherwise objectionable. They are usually secured in position upon the screen frame. by numerous nails driven through them into the wooden frame. A liner for a single sieve compartment isordinarily formed of four strips or sections, each held in place by from six. to ten nails. In the operation of the screens it is necessary from time to time to remove the liners for cleaning purposes or to replace worn liners.

Each time; this is, done from twenty-four to forty nails must be withdrawn from and re-' inserted into the wooden frame. This results in great damage to the frame, rendering it incapableof having liners attached to it and compelling it to be discarded and replaced whileitis otherwise in satisfactory operative condition.

One of the principal objects of my present invention is the provision of a sieve or screen liner which will present a smooth unbroken sur face to the material on the screen, and which will be free of joints, crevices or recesses in,

which the material might lodge and be retained.

Anotherobject is the provision of a unitary sieve liner of convenient and efficient form which may readily be applied to and removed or composition which is readily adjustable to sieves of different sizes, shapes or dimensions, and which will, by reason of its resiliency, increase the activity and promote the effective functioning of sieve cloth cleaners operatively positioned relative to the sieve A still further object is the provisionfof an integral sieve liner, which may be readily and economically produced of rubber, rubber composition or other suitable preferably resilient moldable material. I

The invention by which these objects are realized comprises a liner shaped, formed and constructed in the manner illustrated in the, accompanying drawing and more fully explained and defined in the following description and claims: a

In the drawing: I Figure l is a perspective view of the preferred form of the liner which constitutes my inven-, tion.

Figure 2 is a top plan view of a sifting screen or sieve comprising a marginal frame and partitions with sieve cloth and cleaner support se- 25; from a screen, with comparatively little, if any,

Figure 4 is a central sectional view of my cloth cleaner shown in Figure 3.

My liner is designed to be applied to a frame B, preferably composed 'of side pieces or strips II and end pieces l2, and supporting a sieve cloth l3 of silk or'other suitable fabric anda sieve cleaner support I4 preferably of reticulated liner. The inner sides, 3 of the liner may. be

beveled, curved or rounded, but are preferably flat plane surfaces with the corners! rounded.

While my liner, is preferably of rectangular form or shape, and is so illustrated, it may be of circular or annular form or of any shape and/or dimensions necessary to adapt it to 7 screen frames of other shapes and dimensions.

The necessity" of producing liners of different dimensions is largely eliminated, however, by the flexibility and elasticity of my liner, any

individualliner being capable of considerable stretching to fit frames of different shapes and sizes.

The adaptability and adjustabilty of my liner are of particular importance and usefulness. The liner is made in one piece, preferably in a mold of suitable construction. It combines the desirable attributes of firmness, resiliencypflexible adjustability and long life. These characteristics are inherent in the liner by reason of the material of which it is formed. The material best suited forv this purpose is soft smooth rubber of non-blooming stock, cured without sulphur, or closely similar rubber composition.

Such" materials are well known, being commonly employed in the various arts for cushioning and shock absorbing purposes.

My invention is not limited to the use of any specific rubber or rubber composition, as any kind of rubber, rubber composition or other suit-' able plastic composition may be employed which is adapted to form a tough wear-resisting and semi-rigid but flexible and resilient rubber-like strip or frame of smooth texture.

My liner is'readily secured in pos'ition'and,

because of its'resiliency, clings or adheres closely to theframe. It may be nailed or otherwise secured to the frame. If .nails are used one or two small nails in each of the rounded and preferably thickened corners will be sufficient. Byvirtue of its flexibility a liner embodying my invention is not restricted in its use to any one frame of certain shape or dimensions. The liner may be, and preferably is, made sufficiently thin to have considerable flexibility and elasticity and anyone or more of its sidesmay consequently be stretched lengthwise in the same manner as an ordinary heavy rubber band. In this way my liner may be stretched to fit sieve frames of various sizes and shapes. It may be used either above or below the screen cloth, or inboth locations, where the particular frame construction permits or renders such use of the liner possible and desirable or useful. The liner is easily and quickly applied and firmly held in, place. It is usually applied and secured to the frame in' stretched condition.

Under certain conditions the natural resiliency of the liner exerts sufficient gripping action to hold it in position when it is compressed and sprung into the frame. Various other modes of securing theliner' in position maybe used.

)If nails are employed, only 'a few small nails in the corners will be needed, no nails or other fastening means between the corners being required. In this respect my liner is a considerable. improvement over the fabric and sectional wooden liners heretofore known and now in use, which require nails entirely around all sides, the total number necessary being several times the number required for my liner. The damage to the wooden sieve frames which results from the repeated driving andwithdrawal of so large a number of nails is obviated or greatly lessened by the use of my one'piece resilient liner. The

application of my liner to a screen frame is much more simple than the matter of securing 'fabric or sectional wooden liners in place.

There is a considerable saving of time and trouble.

My liner also possesses the advantage of completely filling. up the corners of the frame, which the fabric liners now in use cannot accomplish, and of eliminating altogether the existence ,of the angular corners, joints and crevices always present in the wooden liners now in use, which are formed of four sections. One of the points of superiority of my liner, therefore, is that it is clean andsanitary, particularly because it is not porous. permits no particles of material'to cling to it, and affords no recesses for the col lection of particles of dirt or for the hiberna tion of weevils. r I r An additional feature of advantage of my liner, as compar'edwith the known fabric and wooden liners. is its usefulness in association with sieve cloth cleaners.

In order to obtain a satisfactory sifting operation, it is essential that the meshes of the screen cloth be maintained in free and open condition. To this end cleaners of various kinds have been designed to knock or jar the fine screen cloth of vibrating screens-so as to loosen the material from the meshes of the screen and throw it upwardly. The result sought by all such devices is to maintain the mass of material in a constant, dancing motion. The efficiency of such devices dependsin large measure upon their activity, i. e., upon the rapidity and extent of their movement. Among the schemes proposed for accomplishing the desired result, balls or other loose pieces of metal have'been arranged upon a reticulated or screen-like support (similar to the cleaner support, l4 shownj herein), the support being disposed below the screen cloth l3 to be cleaned and so spaced from it that the loose pieces would at frequent intervals strike the screen cloth when the cloth and the lower support werevibrated together.

A form of screen cloth cleaner device which I have invented and found to be more efficient and generally more satisfactory than prior'devices comprises a soft body of rubber or rubber composition in the form of a substantially flat upper surface and having upon its lower'surface an integrally formed rounded'knob, This device is described and claimed in acopending application, Serial No. 652,215, filed January 17. 1933.

In use, one or more of my cleaner devices are placed upon a support ll of wire, fabric orany other suitable material immediately beneath the screen cloth 13 to be cleaned. The screen cloth l3 and support l4 may be secured in fixed relationship in the frame A, which may be vibrated, oscillated, gyrated or otherwise agitated by any suitable mechanism (not shown) in the performance of sifting or screening operations. Both the cleaner device and sieve liner, however, are adapted to be used upon sieves or screens of this general character whether the support I4 is fixed to vibrate with the screen cloth l3 or is separate therefrom and itself either movable or stationary. The screen cloth may be of any suitable character and mesh. The support I4 is preferably reticulated and of relatively coarse mesh, but may be imperforate where the machine in which it is used is of such design as to permit.

In the operation of the sieve or screen illustrated herein, the screen cloth l3 and support M are vibrated or otherwise agitated as a unit. The cloth cleaner devices C rest upon their rounded knobs 22 upon the support l4, their upper surfaces being either in contact with the screen cloth or sufficiently close thereto to contact therewith during the operation of the screen. Agitation of the frame carrying support l4 and screen cloth I3 gives the cleaner devices a slight but eificient bounding or bouncing movement accompanied by constantly varying tilting movements occasioned by the unbalanced condition of the devices upon their rounded knobs 22. The cleaner devices consequently strike the screen cloth I3 at frequent intervals but at different points and varying angles. Sometimes the entire top face of the device strikes flatly against the under side of the screen cloth, on which occasions the recess 24 exerts an action similar to that of a vacuum cup; the device attaches itself momentarily to the cloth and is released by the continued vibration of the screen cloth l3 and support I 4. At other times first one edge of the cleaner and then another is tilted against the screen cloth. This tilting, bounding and cupping action is continuous.

The cleaner is ordinarily sufficiently active and its contacts with the screen cloth sufiiciently violent to afford ample and satisfactory cloth cleaning action. Its eflicie'ncy is increased, however, when a screen cloth cleaner C of this character is used in a screen fitted with the resilient liner A disclosed in my present application. When so used, the cleaner device of resilient material, in the course of its movement upon the vibrating support I4, comes frequently into contact with the liner A, and rebounds therefrom, the rebounding action being amplified by the resiliency of the liner.

These contacts occur at points on the liner between the corners, the cleaner practically never striking the liner at the corners where the nails may be located.

Hence, no matter how badly worn my liner may become, the cleaner device used with it cannot be injured by contact with exposed nail heads. In this respect my resilient liner is superior to the old fabric and wooden liners which are secured by nails throughout their extent. When these old liners begin to wear away through continued use, the nail heads are left exposed along the sides of the frame, between corners where the cleaner repeatedly strikes. The result, of course, is excessive wear of and damage to the cleaner device. The avoidance of this damage by the use of my liner is a distinct benefit, regardless of the type or form of cleaner device which may be associated with it As previously indicated, the cleaner device 0, which is most advantageous in connection with my liner A, comprises a body 2| preferably in the form of a generally fiat rectangular shape, provided on its under side with a rounded supporting knob or button 22 preferably integral with the body 2|. The knob or button may be made entirely of the same rubber, rubber composition or other resilient plastic material of which the body 2| is composed, the whole being formed integrally preferably by moulding. Or the knob may be composed wholly or partially of a rounded metal head, cap or insert 23 seated upon or embedded in the knob 22, in order to provide a relatively hard wear-resisting sur face at the point of most frequent contact with the metal of the support 14. The preferred manner of producing the device is to mold the entire device in one piece with the metal insert 23 incorporated as a part of the integrally formed rounded knob 22.

The body 2| of the cleaner is preferably formed with a recess 24 on its upper side. This recess may vary in size and shape, but for best results should be circular, or substantially circular, and of a diameter and depth sufiicient to effect a cupping or vacuum action upon the screen cloth l3 when the upper surface of the body 2| comes into contact with the cloth.

My cleaner device may be made of different shapes and proportions. Both the cleaner and the linerdescribed herein may be used with sifting or shaking screens of different kinds for various materials as well as flour and the other substances specifically mentioned. My invention is not limited to the dimensions of theliner or of the cleaner, as illustrated, the drawing merely showing the preferred form. of embodiment of each.

I claim:

1. A liner for sieves comprising an integral frame-like body of rubber composition adapted to be secured to the inner surface of a sieve frame, and having relatively thin flexible side and end walls and relatively thick corners rounded on their inner surfaces.

2. A sifting apparatus comprising a frame, a screen cloth secured upon said frame and an integral endless elastic rubber liner secured to the inner surface of said frame adjacent said screen cloth and extending entirely around the margin thereof.

3. A liner for sieves comprising an integral endless body adapted to be secured to the inner surface of a sieve frame, said body having relatively thin elastic portions adapted to be positioned against the walls of said frame and spaced relatively thick portions on said body to fit the corners of said frame.

4. A sifting apparatus comprising a frame, a screen cloth secured upon said frame, and an endless elastic liner extending entirely around the inner surface of said frame adjacent said screen cloth and secured thereto in stretched condition.

HARRY B. RICE.

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