US3250389A - Line sifter - Google Patents

Description

May 10, 1966 s. R. scRuBY ETAL 3,250,389

LINE SIFTER Filed Jan. 28, 1965 WWM\\N MN l .w n 1 Swa\\ s Nu Nm .h//r\\ wm n I @,(YF. N\ J\ 1.1 n E Ml 'i A JH QM, WM M ma, a ww s i u M x 1r L V INVENTORJ ATTORNEY United States Patent O 3,250,389 LINE SIFTER Stanley R. Scruby and Donald J. Mclver, Houston, Tex., assignors to Systems Engineering and Manufacturing Co., nc., Houston, Tex., a corporation of Delaware Filed Jan. 28, 1955, Ser. No. 428,747 2 Claims. (Cl. 209-250) This invention pertains generally to classifying apparatus and methods and particularly to an improved vibratory sitter and methods utilized therein, and is a continuation in part of my application, Serial No. 207,190, now abandoned, tiled July 3, 1962.

Various types of sifting or classifying apparatus and methods have been developed for handling pulverized or powdered substances such as our. In particular, reciprocating or vibratory sitters of various types have been used extensively in prior art devices. For example, United States Patent 3,021,952, issued on February 20, 1962, to K. R. Powell, United States Patent 3,021,953, issued February 20, 1962, to W. A. Brastad et al. disclose sifters or classifying apparatus wherein a reciprocating or vibratory movement is utilized.

Although many of the prior art devices have proven to be satisfactory in some respects, such prior art devices leave much to be desired in the way of optimum design and performance to assure rapid and effective classifying of solid particles having various sizes. Prior art classifiers have been large since the inputs to the classifiers must be diverted from the in-line path of the incoming material. Also known classiiiers have not been pressure tight thereby requiring terminating and air separating means at the input to the classifier and an air-lock feeder at the output of the classifier whereby the material is introduced into another air stream for distance conveying,

Thus, an object of the present invention is to provide an improved reciprocating, classifying apparatus and to provide improved classifying methods.

Another object of the present invention is to provide apparatus and methods of classifying solid particles Wherein such solid particles are conveyed by the velocity of a source of air under pressure into a pressure tight classifying or vibratory apparatus, the air serving as a conveyor and yet not forcing the solid particles through the sifting screens.

Yet another object of the present invention is to provide improved classifying or vibratory apparatus and methods which are characterized by simplicity, economy, and eifectiveness of operation inasmuch as conventional air separation at the entrance to the classifying apparatus is eliminated as well as recombining mechanism at the discharge of the classifying apparatus.

Still another object of the present invention is to provide improved classifying or vibratory apparatus and methods wherein solid particles are conveyed by the velocity of a source of air under pressure through an input into a pressure tight chamber having an outlet for those particles which have not been screened or sifted in the chamber and another outlet for those particles which have been sifted or screened in the chamber, with only one air source serving as a conveying media into and out of the classifying apparatus.

In the drawing, FIGURE 1 is a partial-sectional, elevational view of apparatus which incorporates the present invention.l

Brietiy stated, the invention provides apparatus an methods for effectively classifying solid particles which have been conveyed by the velocity of a source of air ICC under pressure into a pressure tight chamber. The chamber has a deflection member or baie at the input and screening means' through which particles of a maximum size are sited or screened as the chamber is motivated by means which cause such chamber to vibrate or oscillate. The chamber has two outlets therein, one for removal of particles which were not sifted or screened and one for removal of particles which have been sifted or screened. 0f course a plurality of sifting screensmay be utilized, perhaps with a separate exit for each strata, as desired. The same conveying media which brought material into the chamber is used for removing the unsifted material from the chamber.

Referring now to the drawing in detail, a pressure tight chamber 10 is shown comprised of a plurality of sections- Which may be identified as a bottom 12, top 14, and members 16 and 1S which comprise one end of the chamber. At the opposite end of the chamber are members 20 and 22 which form the other end of the chamber. Side 24 is disposed between the bottom 12 and top 14 and inasmuch as a section view is shown, another side is required to complete the chamber configuration. Although a preferred type of vchamber is shown in the drawing it is to be understood that any suitable conliguration of chamber may be utilized without departing from the spirit of the invention, so long as such chamber is pressure tight. The internal pressure within chamber 10 is substantially uniform throughout. t

Chamber 10 is divided into an upper portion 26 and a lower portion 28 by a screen or a sifting member 30. The screen or sifting member 30 has a plurality of apertures therein. The size of such apertures is dictated by the maximum size of particles to be passed through such apertures into the lower portion 28 of chamber 10. Screen or sifting member 30 is positioned at one end of the chamber 10 at point 32 between members 16 and 18 and the opposite end of the screen member 30 is positioned on member 46 at point 34.

The chamber 10 is coupled to a suitable pipe or duct 36 through a iiexible coupling 38. Flexible coupling 38 is attached to duct section 40 of the chamber 10.I A source of solid particles is fed through pipe 36 into the chamber 10, and deiiected downwardly by baie 41 onto the screen 30. However, it should be noted that inasmuch as it is undesirable, with respect to the sifting of certain commodities, for example, flour, production being in accord with appropriate Federal Regulations, for the air to materially assist the solid particles in passing through screen 30. Said particles pass through said screen by the vibration imparted to member 10 and/ or by gravity ow. Thus the incoming air-particle mixture should be directed in such as manner as to not forcefully impinge on the screen with suicient force to blow said particles through said screen. In this embodiment, baie 41 serves as the directional medium, or force deflector. The solid particles may be of the powdered type developed in various processes during the milling or conveying of flour for example. The solid particles are combined with a source of air under pressure (not shown) so that a combination of air and solid particles are brought into the chamber 10 by the velocity of the lair under pressure. The pressure at which the particle-air combination is passed into the chamber 10 may be varied for particular requirements but a satisfactory velocity has been obtained with a pres sure of about tive pounds per square inch.

Discharge outlets 42 and 44 are used lfor removing the sifted or screened particles and the unsifted particles in a manner to be explained su-bsequently. Curved member 46 acts as `a divider for the discharge outlets 42 and 44.

The chamber 1t? is supported near the end having the discharge outlets by a member 48 coupled through a flexible coupling to member 50. Member 48 may be welded to the chamber 10 by welds 62 and 64. Member 50 may be welded to a platform or base 7G by welds 66 and 68. The flexible coupling which joins member 48 to member 50 may be constructed of any suitable material such as a flexible nylon sheet 52. The flexible coupling should be rigid enough to support the chamber but also flexible enough not to break during vibratory movement of the chamber. Sheet 52 may be coupled at its upper portion t member 48 by bolts similar to bolt 54 which passes through member 48 and sheet 52 and is threadedly coupled to a nut 58. The lower portion of sheet 52 may be coupled to member 50 by bolts similar to bolt 56 which passes through member Si) and sheet 52 and is threadedly coupled to a nut 60.

Disposed `at the end of chamber 1t) opposite the discharge outlets 42 and 44 is a member 84 which is fxedly coupled to the chamber in any suitable manner. Member 84 is coupled to an eccentric 82 which is driven by a shaft 80. Shaft 80 is coupled to a member 78 which is concentric to shaft `bil. Member 78 is coupled through suitable coupling means such as `a belt 76 to a motor 72. Motor 72 has a sheave member 74 coupled thereto on which belt 76 is movably attached. Motor 72 and member 7 8 may be positioned on platform 7 t) by suitable means 73 and 75, respectively.

Thus during operation of the apparatus, motor '72 is driven by a suitable energy source such as electric power. The motor drives the eccentric means to cause oscillation or vibration lof the chamber means. Provision maybe made to vary the motor speed thereby varying the oscillation period of the chamber means. The positioning of flexible sheet 52 prevents the oscillatory movement of chamber 10 from being substantially retarded. As the chamber means is oscillated or vibrated, the selected maximum particle size of the solid particles being fed into the chamber means are passed through the sifter or screen member 32 and into the lower portion 28 of chamber 10. Inasmuch as the solid particles are brought into chamber 10 by the velocity of the air under pressure, the reciprocating movement of chamber 10 causes the same particles to be sifted and'to continue movement toward exits 42, 44. These sifted particles are called throughs and are discharged from discharge outlet 42. The solid particles which `are too large for passing through the sifter or screen member (also called overs) aredischarged through discharge outlet 44 at the end of chamber 10 opposite the inlet 36. Since the chamber is pressure tight, and the pressure substantially uniform throughout member 10, the

t volume of air under pressure serves as a discharge media as Well as an input media thereby eliminating an air separator at the input Iand eliminating mechanism for recombining the particles and air at the output.

The present invention overcomes many of the difficulties encountered previously in sifting apparatus and methods inasmuch as in the present invention the solid particles are combined with air under pressure to provide a combination -of air and solid particles as an input to the chamber means. The chamber means is oscillated or vibrated by oscillating means which includes eccentric means well known in the art. The sifting is accomplished by such vibration, in that the incoming air-particle mixture is deviated from directly owing toward .the screen. If the inlet conduit did directly lead toward the screen, the air, under pressure, would exert significant force on the particles and thereby assist the particles, and associated foreign matter, in passing through the screen. Flexible couplings allow means to drive the chamber means in an oscillating or vibratory manner. Discharge means are provided for the particle-air combination which is passed through the sifting means in the chamber means and for discharging the particle-air combination which did not pass through the sifting means. The same source of air velocity serves as a conveying media for discharging particles as well as introducing particles into the chamber means. Turbulence in the lower portion of the chamber means is maintained at a minimum thereby preventing blow-back of the sifted particles.

Hereinafter follows a brief explanation of the advantages of the air conveyor operation. It has been mentioned that vessel 10 is intended to have substantially uniform pressure throughout. Through duct section 4@ enter the air-particle mixture, having a certain velocity. Directional means, herein shown as baffle 41, is provided for the purpose of assuring that the particle mixture will not be forced by air velocity through the fine mesh, but will pass therethrough by virtue of reciprocation and gravity fiow. inasmuch as the air will still have a force vector direction or velocity after entering the chamber, this velocity will be suicient to again permit the overs and throughsto rejoin the air carrier in either of ducts 42, 44.V By the means of said air-conveyor the overs and throughs, or coarses and iines, may, after sifting, be conveyed to remote points for further operations.

Although a preferred embodiment of the invention has been shown and described, the scope of the invention is defined by the following claims. Although such claims may be presented in indented format to facilitate reading and understanding thereof, such indented format is not intended as a structural or functional limitation of any of the elements or steps recited in the claims.

We claim:

1. Apparatus adapted for separating particles, said apparatus including in combination: Chamber means being pressure tight and having screen means positioned interiorly of said chamber means, said chamber means having uniform pressure therethrough; conduit means coupled to one end of said chamber means permitting a pressurized mixture of air `and solid particles to enter said chamber means; means directing the flow of said pressurizedl mixture into the interior of said chamber in such a manner that said air portion of said pressurized mixture does not materiallyforce said solid particles to pass through said screen means, said directing means being positioned adjacent the juncture of said chamber land said conduit; oscillating means coupled to one end of said chamber means to cause preselected particles to be sifted through said screen means; first and second discharge means coupled to said chamber means, said discharge means being so positioned with respect to said conduit means as to permit pressurized exiting of a mixture of said pressurized air and unsifted particles through one of said discharge means conjointly with pressurized exiting of a mixture of said pressurized air and sifted particles through the lother of said discharge means; said oscillating means includes a platform, a motor mounted on one end of said platform, eccentric means coupled to said motor and to said chamber means, and a flexible coupling at the other end of said chamber means connecting said platform to said =chamber means thereby permitting said chamber means to move in response to rotation of said eccentric means. f

2. A method for continuously providing, sifting and exiting an air-particle mixture to and from `a pressure tight chamber comprising the steps of:

retaining the internal pressure Within said pressure tight chamber substantially constant during operation; causing a pressurized mixture of air and solid particles to be directed into said chamber;

deecting said air-particle mixture from its line of entry into said chamber so` that the force with which said particles strike internal screening means within said chamber is insuicient to cause said particles to pass through said screening means;

mechanically reciprocating said chamber to cause line portions of said particles to pass through said screening means; l

5 6 exiting, under force, coarse portions of said particles References Cited by the Examiner from said chamber through an outlet, 4by means of UNITED STATES PATENTS a current of air which formed a p-ortion of the initial air entering Said Chamber; and '398,692 2/1889 Blttlnger 209-3 18 X exiting, under force, said ne particles from said chani- 5 1,528,983 3/1925 Montgomery 9*250 X =ber through a further outlet, by means of a current 11541399 6/1925 Thomson 9 250 of air which formed a portion of the initial air enter- '310211953 2/1962 Brastad 209-233 X ing said chamber, whereby by virtue of the force P yattributable to said air current, said iine particles HARRY B'THORNONPHma'y Examiner' may be moved a substantial distance from said lo R. HALPER, Assistant Examiner. chamber.

Claims (1)

1. 2. A METHOD FOR CONTINUOUSLY PROVIDING, SIFTING AND EXITING AN AIR-PARTICLE MIXTURE TO AND FROM A PRESSURE TIGHT CHAMBER COMPRISING THE STEPS OF: RETAINING THE INTERNAL PRESSURE WITHIN SAID PRESSURE TIGHT CHAMBER SUBSTANTIALLY CONSTANT DURING OPERATION; CAUSING A PRESSURIZED MIXTURE OF AIR AND SOLID PARTICLES TO BE DIRECTED INTO SAID CHAMBER; DEFLECTING SAID AIR-PARTICLE MIXUTE FROM ITS LINE OF ENTRY INTO SAID CHAMBER SO THAT THE FORCE WITH WHICH SAID PARTICLES STRIKE INTERNAL SCREENING MEANS WITHIN SAID CHAMBER IS INSUFFICIENT TO CAUSE SAID PARTICLES TO PASS THROUGH SAID SCREENING MEANS; MECHANICALLY RECIPROCATING SAID CHAMBER TO CAUSE FINE PORTIONS OF SAID PARTICLES TO PASS THROUGH SAID SCREENING MEANS; EXITING, UNDER FORCE, COARSE PORTIONS OF SAID PARTICLES FROM SAID CHAMBER THROUGH AN OUTLET, BY MEANS OF A CURRENT OF AIR WHICH FORMED A PORTION OF THE INITIAL AIR ENTERING SAID CHAMBER; AND EXITING, UNDER FORCE, SAID FINE PARTICLES FROM SAID CHAMBER THROUGH A FURTHER OUTLET, BY MEANS OF A CURRENT OF AIR WHICH FORMED A PORTION OF THE INITIAL AIR ENTERING SAID CHAMBER, WHEREBY BY VIRTUE OF THE FORCE ATTRIBUTABLE TO SAID AIR CURRENT, SAID FINE PARTICLES MAY BE MOVED A SUBSTANTIAL DISTANCE FROM SAID CHAMBER.

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