US3456794A - Screeners - Google Patents

Description

S. H. INGRAM Jul 22, 1969 SCREENERS Filed June 2, 1967 INVENTOR. STU/4E7 M INGRAM A TTOR/VEY6.

nited States Patent 3,456,794 SCREENERS Stuart H. Ingram, 1749 Oakdale St. 5., Pasadena, Calif. 91106 Filed June 2, 1967, Ser. No. 643,120 Int. Cl. B07b 1/28 U.S. Cl. 209-316 8 Claims ABSTRACT OF THE DISCLOSURE A screener according to the present disclosure comprises a housing having a chamber through which particles (or pieces) are passed. A plurality of screens, each having a different hole size are disposed within the chamber at an inclined position substantially occluding the horizontal section of the chamber. The uppermost screen has the largest hole size, and each succeeding screen below it has a smaller hole size. An opening is provided through the side of the housing to the chamber adjacent to and above the lowermost edge of each inclined screen, to pass pieces (or particles) retained by the screen to an external hopper. Vibrating means vibrates the housing and screens, and an airflow through the chamber is provided. According to an optional feature, an inclined baffie is positioned above each inclined screen for directing particles to the uppermost portion of such screen.

The present invention relates to screeners, particularly to Screeners for separating or classifying random-shaped material into a plurality of size ranges.

Screeners have heretofore been used for both laboratory and production techniques for separating material such as rock aggregate into a plurality of size ranges and for classifying material such as factory floor sweepings. These screeners have comprised a housing having a chamber disposed therein and a plurality of horizontally disposed screens of varying hole sizes, the uppermost screen having the largest hole size and the lowermost screen having the smallest hole size. The material to be separated or classified, such as rock aggregate or floor sweepings, was placed into the housing above the uppermost screen and the screens were vibrated so that the particles (or pieces) passed through the screens. Large sizes of material were retained on the upper screens, and smaller sizes on the lower screens. After vibrating the screens for a sufficient period of time, the particles became separated into various size ranges and the particles (or pieces) were removed by opening the housing and removing the screens, and removing the particles which rested on the screens.

It is an object of the present invention to provide a screener whereby material may be continuously separated or classified into different size ranges, and particles in the ranges are continuously discharged from the screener. The device can thereby be operated continuously and for the same bulk has a capacity greater than that of conventional devices.

Another object of the present invention is to provide a screener having means for removing dust from within the housing in order that it can be used in a laboratory without excessive dust in the room.

A screener according to the present invention comprises a housing having a chamber therein through which material to be separated or classified is passed. A plurality of screens, each having a different hole size, are disposed within the chamber at an inclined angle to the horizon and substantially occluding the horizontal section of the chamber. The uppermost screen has the one above it, the lowermost screen 19 having the smallest 3,456,794 Patented July 22, 1969 largest hole size and each succeeding screen thereunder has a smaller hole size than the one above it, the lowermost screen having the smallest hole size. An opening is provided through the side of the housing into the chamber adjacent to and above the lower edge of each screen. Vibrating means is provided for vibrating the screens. Material to be separated or classified is in troduced into the chamber above the uppermost screen and is separated or classified into a plurality of size ranges depending upon the hole sizes of the screens, and the particles of each size range are continuously discharged from the chamber through each opening.

An optional and desirable feature of the present invention is the provision of differential pressure means for removing dust from the chamber.

Another optional and desirable feature of the present invention is the provision of adjustable means for .adjusting the slope of the screens.

Another optional and desirable feature of the present invention is the use of round-hole screens.

Another optional and desirable feature of the invention is the provision of ramps adjacent each opening to facilitate delivery of particles separated or classified into separate size ranges to separate hoppers.

A screener according to the present invention is useful for separating rock aggregate into a plurality of size ranges. The rock aggregate so separated is useful for controlled sizes of rock filler in cement, gravel roofing material, and the like. Also, the screener according to this invention is useful for separating various sizes of bodies such as nuts, washers, bolts, and rivets. Further, the screen according to this invention is useful for salvaging and classifying useful parts from industrial floor sweepings, for example where a careless worker has dropped usable parts on the floor which become lost in other waste material already present on the factory floor.

The above and other features of this invention will be fully understood from the following detailed description and the accompanying drawings in which:

FIG. 1 is a side elevation in cutaway cross-section of the presently preferred embodiment of a screener accordin g to the present invention;

FIG. 2 is a top view elevation of a screen for use in the screener illustrated in FIG. 1;

FIG. 3 is a graph comparing the size ranges produced by round-hole and square-hole screens; and

FIG. 4 is a side elevation in cutaway cross-section of means for adjusting the slope of screens for use in the screener illustrated in FIG. 1.

In FIGS. 1 and 2 there is illustrated a screener according to the presently preferred embodiment of this invention. The screener comprises a housing 10 forming a chamber 12 therein. Hopper 14 is provided at the uppermost portion of chamber 12, to permit the introduction of material to be separated into size ranges into. the chamber. 1 j

A plurality of inclined screens 16, 19 are provided within the chamber and substantially occluding the hori-. zontal section of chamber 12. The uppermost screen 16 has the largest hole size (largest mesh) and each succeeding screen thereunder has a smaller hole size than the hole size (smallest mesh). The screens are inclined from the horizontal (as shown in the drawings) and preferably at opposite angles from the preceding screen. Although the screens may be inclined at any suitable slope, it has been found that an angle of inclination of between 15- 30 is suitable for most purposes. A plurality of baflies 2023 are disposed within chamber 12 at an inclined angle above each screen 16-19, bafiles 21-23 being spaced below screens 16-18. Openings 2427 provide a passage between a baffie and a wall of the housing immediately above the uppermost edge of a screen so that particles (or pieces) passed through the screen will be passed to the upper edge of the next, lower screen.

If desired, the screens may be assembled into chamber 12 by sliding the screens into place and attaching them with bolts or other attachment means (not shown). The screens therefore may be removed for cleaning purposes or may be replaced with screens of other desired sizes.

Openings 28-31 are provided through the wall of housing immediately adjacent the lowermost edge of each respective screen 16-19, openings 28 and 30 passing through the opposite wall. Inclined ramps 32-35 are provided at the lower edge of each inclined screen to permit passage of material retained above each screen to suitable hoppers 36-39. Ramps 32-35 are preferably provided with side walls 40-43.

Housing 10 is mounted on springs 44 which in turn are mounted on base 46. Springs 44 permit free movement and vibration of housing 10 and screens 16-19 therein, relative to base 46 which will not vibrate.

Base 46 encloses vacuum pump 47 and vibrator 48. Vacuum pump 47 is provided with a vacuum bag 50 for the collection of dust, debris and aggregate passed by the finest screen 19. The motors of vacuum pump 47 and vibrator 48 are connected to a suitable source of electrical energy through fuse 52, rheostat switch 54 and plug 56. Vibrator 48, which may for example comprise an eccentrically weighted motor, is mechanically connected to housing 19 so as to vibrate the housing and screens when the vibrator is operated.

The inlet portion 58 of vacuum pump 47 is disposed within funnel 60. Funnel 60 extends into the lower portion of chamber 12 adjacent the walls of housing 10 below the lowermost screen 19.

Slide valve 62 is provided in hopper 14 and is adapted to contact baflle so as to control the rate of flow of material from hopper 14 into chamber 12. Slide valve 64 is provided within funnel 60 so as to control the rate of flow of air through chamber 14 into vacuum pump 47.

In operation of the screener illustrated in FIG. 1, material to be divided into size ranges, such as rock aggregate, is introduced into hopper 14 and flows into chamber 12 at a rate determined by the setting of slide valve 62. Rheostat switch 54 is turned to a suitable position to energize vacuum pump 47 to create a differential pressure within the chamber so that air is drawn through the chamber and into inlet 58 of the vacuum pump. At the same time vibrator 48 produces vibration at a desired frequency to vibrate housing 10, screens 16-19 and ramps 32-35. The frequency of vibration and the volume of air drawn through the chamber are adjustable by adjusting the setting of rheostat switch 54. Alternatively, separate rheostats may be provided for independent settings of the vacuum pump and the vibrator.

Rock aggregate in hopper 14 is deflected initially by bafile 20 through opening 24 and to the upper portion of the uppermost screen 16. Rock aggregate smaller than the size of the holes in screen 16 passes through screen 16 and is deflected by baflle 21 through opening to the uppermost portion of screen 17. Rock aggregate which is retained on screen 16 flows through opening 28 and down ramp 32 to hopper 36. Similarly, rock aggregate larger than the holes in screen 17 passes through opening 29 and down ramp 33 to hopper 37; rock aggregate larger than the holes in screen 18 passes through opening and down ramp 34 to hopper 38; rock aggregate larger than the holes in screen 19 passes through opening 31 down ramp to hopper 39, and rock aggregate smaller than the holes in screen 19 is drawn through vacuum pump 47 to vacuum bag 50.

A preferred but optional-feature of this invention resides in the fact that vibrator 48 vibrates not only the screens but also the housing. Thus, the rock aggregate 4 is not only agitated to enable it to pass through the permissible screens, but is also agitated to slide it down the respective screen which retains it and along the respective ramp. By vibrating the entire housing, a continuous discharge of rock aggregate from the various openings into the respective hoppers is assured.

Rock aggregate may be continuously added to hopper 14 so as to permit the continuous separation of aggregate into a plurality of size ranges without having to stop the screener at periodic intervals to remove rock aggregate from the chamber. Thus, the quantity of rock aggregate to be separated by the screener is not limited by the size of chamber 12 or housing 10.

FIG. 4 illustrates an adjustable means whereby the slope of the angle of inclination of the screens may be adjusted to any desirable angle. One edge of screen is pivotally mounted by pivot means 82 to wall 84 of the housing. The opposite edge of screen 80 is supported by ramp 86. A cap screw 88 passes through the screener and ramp and carries bolt 90 to hold the assembly together. Compression spring 92 is placed between the ramp and screen and biases them apart. By axially turning the cap screw or bolt, the distance between the screen and ramp maybe changed, thereby changing the slope of the screen. Pivot means 82 may be removable so that the screen may be removed and replaced with another screen of different size or type by removing cap screw 88 and pivot means 82.

Although any type of screen may be used for screens 16-19, it is a preferred feature of the present invention to utilize a round-hole screen for the separation of rock aggregate into size ranges. In FIG. 3 there is illustrated a graph comparing the size ranges formed by round-hole screens and by square-hole screens. The unshaded columns represent an analysis of size ranges of aggregate separated by round-hole screens, and the shaded columns represent an analysis of size ranges produced by square-hole screens. Five screen sizes are illustrated in the graph of FIG. 3; 0.187 inch, 0.250 inch, 0.312 inch, 0.375 inch and 0.437 inch. These screen sizes separate aggregate into size ranges between the size of the screen, each size range being 0.0625 inch.

' The limits for a size range are determined by the hole size of two screens, one above the other. The upper size limit depends on the hole size of the upper, or larger, screen, while the lower size limit is dependent on the hole size of the lower, or smaller, screen.

Woven screens, having square holes, contain two passing dimensions for each screen. One passing dimension is the wire spacing, i.e., the perpendicular dimension between the wires, or the side of a square hole, and the other passing dimension is that of the diagonal of the square. The smallest size of aggregate passed by a woven screen or square-hole screen is determined by the wire spacing, while the largest size passed is determined by the diagonal across the square. Thus, the largest aggregate capable of being passed by a woven screen is /2 times the wire spacing.

When dividing aggregate into a plurality of size ranges with a woven or square-hole screen, error is introduced, which error may be determined by multiplying the larger screen size of the size range by /2. Thus, for a size range between 0.375 and 0.437 inch, formed with a woven screen, the size range will actually be 0.375 and 0.676 inch, thereby creating a size range of 0.239 inch instead of 0.0625 inch. Similarly, upper limit error is introduced with a square-hole screen for the other size ranges as indicated in the graph in FIG. 3.

Depending upon how particular random-shaped particles of material are situated on a particular square-hole screen, the screen may or may not pass the particles within the error range, that is, above the smallest dimension of the screen yet below the largest dimension of the in one random position, and yet [may be passed by the same screen by the diagonal dimension if situated in another random position.

With a round-hole screen, both the upper and lower limits of the size ranges may be more accurately controlled. The size of the particles to be passed through or trapped by the screen is dependent on only the diametrical size of the hole in the screen. Thus, with a round-hole screen, error in sizing is virtually eliminated.

FIG. 2 illustrates a round-hole screen for use in the screener illustrated in FIG. 1. A suitable plate 72 is pro-- vided at one end of screen 66 to form a ramp for permitting aggregate not passed by screen 66 to flow. Screen 66 is mounted within housing at an inclined angle, such as shown by screens 16-19. Plate 72 forms the respective ramp 32-35. The screens are preferably removable from housing 10, and are slid into place ani mounted 'by suitable mounting means, such as bolts (not shown).

Other types of screens may be used in the screener according to the present invention. For example, corrugated and slit-type screens may be used for separating usable bolts, washers, rivets, or nuts from waste material. Screens having other types of hole configuration may be used for other purposes.

The present invention thus provides a screener for dividing material into a plurality of size ranges dependent upon the sizes of the screens utilized therein. The screener is also useful for classifying material, such as useful parts, from waste material. The screener provides continuous output of particles of the various size ranges and is not limited by the size of the housing or of the chamber. The screener is accurate, efiicient and easily set up and used under normal conditions. It is easily manufactured and assembled. The screener may be constructed such that the screens are removable so that screens of various sizes and types may be interchanged, to permit the screener to be used for a wide variety of purposes. The screens are flat so that they may be compactly stored.

The screener is particularly adaptable for laboratories in the sense that it may be constructed in relatively small sizes as compared to prior screeners and yet is capable of separating relatively large quantities of material as compared to the size of the screener. Since the vibrating housing is mounted above a stationary base on spring supports, no vibration is imparted to the base or to other delicate instruments in the laboratory. Furthermore, the removal of dust from the chamber and retention of the dust in a vacuum bag prevents dust from being discharged to the room to upset delicate instruments.

This invention is not to be limited by the embodiment shown in the drawings and described in the description which is given by way of example and not of limitation, but only in accordance with the scope of the appended claims.

I claim:

1. A screener for separating particles of mixed sizes into a plurality of size ranges, said screener comprising:

a housing having a substantially vertical chamber through which particles may be passed; a plurality of screens each having a different hole size, each screen being disposed within said chamber at an inclined position having a predetermined slope and substantially occluding the horizontal section of said chamber, the uppermost screen having the largest hole size and each succeeding screen having a smaller hole size than the screen above it, the lowermost screen having the smallest hole size; an opening through the side of said housing to said chamber adjacent to and above the lowermost edge of each inclined screen; adjustable means for selectively adjusting the slope of each screen; suction means mounted to said housing below the lowermost screen for providing a flow of air downwardly through said chamber to draw dust and fine particles through all of said screens; and vibrating means for vibrating said screens, whereby when said screens are vibrated by said vibrating means, particles introduced into said chamber above the uppermost screen are agitated so as to permit particles to pass through those screens having a larger hole size than the particles, whereby the particles are separated into a plurality of size ranges, and the particles in each size range pass through respective ones of said openings.

2. A screener according to claim 1 wherein the holes in each screen are substantially round.

3. A screener according to claim 1 wherein the openings associated with each of the inclined screens are successively on opposite sides of the chamber.

4. A screener according to claim 1 further including a ramp mounted to the housing and disposed adjacent to each opening to receive particles therefrom.

5. A screener according to claim 1 further including an inclined baffle above each inclined screen for directing particles to the upper most portion of each inclined screen.

6. A screener according to claim 5 wherein the openings associated with each of the inclined screens are successively on opposite sides of the chamber.

7. A screener according to claim 5 wherein the holes in each screen are substantially round.

8. A screener according to claim 5 further including a ramp mounted to the housing and disposed adjacent to each opening to receive particles therefrom.

References Cited UNITED STATES PATENTS 607,564 7/1898 Gray 209316 887,557 5/1908 Werckle 209316 X 907,348 12/ 1908 Hatfield et a1 2093 18 1,179,842 4/1916 Kirksey 209269 1,426,270 8/ 1922 Fowler 2093 18 TIM R. MILES, Primary Examiner U.S. Cl. X.R.

0%1684 ;;g UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,456,794 Dated July 22, 1969 Inventor(s) Stuart H. Ingram It is certified that error appears in the above-identified patent and that: said Letters Patent are hereby corrected as shown below:

I' Column 3, line 3, "the" should be --one--; Column 3, line 12, after "30" and before "passing" insert --passing through one wall and openings 29 and 31--.

(SEAL) 1 Attest: f WILLIAM E. SO UYIJLR, JR. EdwardM-fl Commissioner of Patents Attesting Officer

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