US2358970A

US2358970A - Screen

Info

Publication number: US2358970A
Authority: US
Publication date: 1944-09-26
Anticipated expiration: 1961-09-26

Description

Sept. 26, 1944. Y 2,358,970

SCREEN Filed Aug. 10, 1942 2 Sheets-Sheet l 38 a7 0 44 o 40 J5: i. 34 o 42 25 z /5 1o /4' a2 E l E 46 TTiORNEY Sept. 26, 1944. N. A. GRAY 2,358,970

SCREEN Filed Aug. 10, 1942 2 Sheets-Sheet 2 A TTORNEY.

Patente'd 26, 1944 PATENT OFFICE SCREEN Newenham A. Gray, Waus'au, Win, assignor to D. J. Murray Manufacturing 00., Wauaau, Wis a corporation of Wisconsin Application August 10, 1942, Serial No. 454,239

' Claims. ('01. ace-2'13) The present invention relates generally to improvements in the art of classifying various materials by subjecting the mixed materials to pulsation of a fluid medium, and relates more speused with varyin degrees of success. While some of these prior devices have proven quite satisfactory for the purpose of treating a few readily separable mixed materials, most of them are relatively crude and inefiicientin action as well as being complicated in structure. Many of the prior pulsating screen separators could not be readily adjusted to meet varying conditions of operation, without interrupting normal operation of the machines; and in addition, most of these prior mechanisms could not be quickly manipulated to provide for varying demands or capacity.

It is therefore a more specific object of the present invention to provide an improved pulsating screen unit which is simple anddurable in structure; sensitive andhighly efiicient in operation, and flexible in its adaptations.

Another specific object of my invention is to provide an improved classifier for mixed granu- 18.:- or fibrous materials, comprising improved screening and pulsating units which are adapted to most effectively co-operate with each other.

A further specific object of this invention is to provide a new and useful hydraulic screen assemblage and mechanism for producing pulsation of liquid therein, wherein mechanical vibrations from the pulsating device will not undesirably affect the screening action, and in which the position of the screen may be varied without interfering with most eiiective operation of the pulsating unit. 1

Still another specific object of the invention is to provide an improved liquid pulsating device having frequency and amplitude varying means which can be adjusted without adversely aiIecting the operation of mechanism which is propelled or actuated by the pulsations, and which device is'capable of generating and transmitting pulsating waves of uniform rhythm and intensity.

An additional specific object of the present invention is to provide a pulsating material classifier having a minimum number of moving parts, maximum capacity with minimum power consumption, and wherein the cost of bothmanufacture and maintenance are reduced to a mini- Still another additional specific object of this invention is to provide an improved pulsatory classifying unit which may be advantageously utilized either singly or in multiple, for either simultaneous or successive stage separation, and

which will insure uniform and most efiicient results under normal conditions of operation.

These and other objects and advantages of the invention will be apparent from the following detailed description.

A clear conception of the several features constituting my present invention, and of the mode of constructing andof operating pulsating screen installations embodying theimprovements, may

be had by referring to the drawings accompanying and forming a part of this specification wherein like reference characters designate the same or similar parts in the various views.

Fig. 1 is a vertical transverse section through one type of my improved pulsating screen wherein a single pulsator co-operates with four screen sections:

Fig. 2 is a top view of the screen portion of the unit shown in Fig. 1;

Fig. 3 is a rear view of the pulsator portion of the unit shown in Fig. 1;

Fig. 4 is a fragmentary horizontal section through the rear of the screen portion of the unit shown in Figs. 1 and 2;

40 Fig. 5 is a diagram showing units of the type shown in Figs. 1 to 4, inclusive, utilized in multip e:

Fig. 6 is'a vertical transverse section through a modified type of screening unit provided with a somewhat deeper syphon liquid discharge;

Fig. 7 is atop view of a further modified pulsating screen assemblage wherein a pair of pul- 1siators each co-operate with a pair of screen secons; I

Fig. 8 is a rear view of the modified improved screening assemblage of Fig. 'I and Fig. 9 is a vertical transverse section through the assemblage of Figs. '1 and 8.

While the invention has been-shown and de scribed herein as being embodied in several specific types of pulsating screen assemblages especially adapted for the purpose of screening fibrous material in the paper industry, it is not my desire or intent to thereby unnecessarily restrict the scope or utility of the improvement.

Referring specifically to Figs. 1 to inclusive of the drawings, each of the improved screen assemblages shown therein comprises in general a four section screening unit Ill co-operating with a common pulsating unit II, and the two units II), II being interconnected by means of a flexible liquid conducting tube I2, and the assemin Figs. 1 and 3, consists primarily of a cylinder 32 the displacement chamber 33 of which is in open communication with the distributing chamber portion 29 through the flexible connecting tube I2, and a piston or plunger 34 rapidly reciprocable within the cylinder 22 by any suitable prime mover such as an electric motor 35 coblages being adapted for use either individually or in multiple as shown in Fig. 5.

Each screening unit I0 consists of an approximately rectangular casing or screen housing I3 and a series of four interchangeably similar screen sections or plates I4 substantially horizontally disposed within the housing I3 and dividing the same into upper and lower chambers I 5, I6 respectively, and the housing I3 may be provided with adjustable supporting feet I 'I. for effecting proper alinement or variation in inclination of the plates I4. The feed end of each housing I3 is provided with an elongated feed launder I8 which communicates with the upper screening chamber I5 over a feed weir I9, while the opposite overfiow discharge end of each housing I3 is provided with a similarly elongated oversize discharge launder 20 having a rearwardly sloping bottom and communicating with an outlet 2I. The lower pulsating chamber II; which is disposed between the feed and discharge launders I8, 20 beneath the screen decks, also has a rearwardly inclined bottom 22 and is divided by transverse partitions 23 into four segregated pulsating sections which approximately correspond in area to the areas of the liquid pervious portions of the screen plates I4. The front ends of all of these pulsator sections of the chamber I6 are in open communication with an elongated syphon duct 24 extending longitudinally of the screeningunit III and communicating with a collecting launder 25 over a series of vertically adjustable weir plates 26. These weir plates 26 should preferably be independently adjustable, and the overflow launder 25 has an outlet 21 near the feed launder acting with the piston through a crank or eccentric 33, and variable speed mechanism. While the variable speed motion transmitting mechanism may be of any desired type, the mechanism specincally illustrated in Figs. 1 and 3 comprises a rocking lever or beam 31 having one swinging end 38 connected to the plunger 34 by means of a connecting link 39. and its opposite swinging end provided with a slot 40 while its medial portion is rockably suspended from afulcrum pin 4I carried by the cylinder 32, The revolving eccentric 33 is pivotally connected to a pivot block 42 by a connecting rod 43, and this block is adjustable along the slot 40 by means of a bell-crank 44 swingably suspended from the fulcrum pin H and having one arm connected to the block 42 by a link 45, while its other arm coacts with a manually adjustable screw 46 swingably suspended I from the cylinder 32. By turning the screw 46,

I8 and a bottom 28 which is inclined toward this outlet.

The rear ends of all of the pulsator sections of the lower chamber I6 open into a distributing chamber portion 29 which communicates with the corresponding pulsator unit II through the flexible connecting tube I2, and entry of pulsating liquid to the several chamber sections or divisions is preferably controlled by means of adjustable streamlined gates 30 operable with the aid of hand levers 3i. Since a, definite hydraulic relation exists between the depth of the lower chamber I6 and the stroke of the pulsator unit II, and the propagation of pulsating waves is a definite function of the pulsating frequency, the sloping bottom 22 of the housing I3 should be so pitched that the pulsating amplitude is transmitted uniformly to all screen plates I4, and that the pulsating frequency at the screen will be synchronous with the impulses generated in the pulsating unit. The adjustable control gates 30 insure uniformity of flow to each pulsating compartment beneath the screen deck; and in units of large capacity undesirable dissipation of the impulses may be further prevented by forming the chamber portion 29 so as to provide a syphon effect.

the bell-crank 44 may be swung in either direction about the pin 4I, so as to move the block 42 within the slot 40 in either direction and to thereby vary the stroke of the plunger 34 and hence the amplitude at the pulsations transmitted to the screens through the liquid body 41, and this variation in amplitude can obviously be effected either .while the motor 35 is in motion or at rest.

Referring especially to Fig. 6, the modified screening unit I0 shown therein is quite similar in general construction to the unit I0 above described, but the modified unit is provided with a somewhat shallower pulsating chamber I6 and with a considerably deeper liquid discharge syphon section 24 at the end of each of the transverse lower chamber sections or divisions. In this modification, the transverse partitions 23' which are located beneath the screen sections I4,

are also extended forwardly through the deep syphon, thereby in fact providing four independent screening devices extending from the distribution chamber 29 to the'liquid overflow launder 25. The remainder of the screening unit I0 is the same as the unit In.

Referring particularly to Figs. 7 to 9 inclusive, the further modified device shown therein embodies a somewhat different screening unit I0" having a still deeper syphon section 24", and a pair of modified pulsating units II", each of which co-o'perates directly with a pair of the screen sections I4, In this further modifled assemblage of Figs. 7 to 9 inclusive, the housing I3" of the screens may-either be formed integral with the casings 32" of the pulsators,

or connected therewith by meansof flexible only through the several sub-divisions of the Each of the improved pulsating units II S own pulsating chamber I6", but all of these partitions 23" preferably extendthrough the deep syphon section 24" so as toprovide four independent syphons. The pulsator units II" of this further modification also differ from the unit II, in that a flexible bellows 34" is rapidly reciprocable in'each oithe chambers 33" formed in the casing 32", and a common electric. motor '35" or other prime mover-is utilized tosimulta neously. but oppositely expand and. contract the two bellows 34". The stroke of the bellow 34" or the amplitude of pulsation. may be varied by adjusting mechanism similar to that previously explained and co-operating with the lever beam 31", and this modified ibellows plunger structure is relatively light and permits more effective packing or sealing of the chambers l3".

This modified assemblageis also simpler and transmitted from the pulsator unit to the screening unit. The functioning or the machine may also be readily controlled by adjusting the vanes 30 and the stroke of the pulsator piston, and theseadjustments may be made while the units remain in operation and without interfering with such normal operation. 7

From the foregoing detailed descrl'ption it will be apparent that my present invention provides an improved pulsating classifier or screeningvdevice which is extremely simple and compact in construction, and whichismoreover highly efilcient in operation. The improved device can obviously be utilized either singly or in any desired multiple arrangement, so as to eflectively classify various kinds of granular or fibrous materials,

and is especially useful in the treatment of pulp in the paper industry. The bellows type ofplunger reduces the weight or the moving parts to a minimum and. also facilitates packing or sealing of the pulsator against leakage, and this rapidly reciprocate the piston 34 and to thereby pulsate the liquid body 41 which fills the displacement chamber 33, tubular connection i2,

chamber 29, chamber l8, and syphon section a 24, and the liquid level should normally extend slightly above the upper surfaces of the screen sections H." The raw or untreated material should thenbe supplied to the feed launder M from which it will fiow over the weir l9'and' upon the screen decks. During advancement of the material along the screen sections it and through the upper chamber IS, the entrained particles of granular material or fibre will be repeatedly subjected to pulsatory liquid action by the rise and fall of the liquid through the liquid pervious portions of the screens, and the smaller particles or fibres will pass through the screens and will eventually be discharged with the excess liquid through the syphon section 24 and over the adjustable dams or weirs 26 into theliquid discharge launder 25. The larger particles which are unable to pass through the perforations of the screens will constantly advance across the screen sections l4 and will eventually be delivered into the launder 20 from which they will be discharged through the outlet 2|. The material is thus gradually and efiectively separated into fine and oversize constituents, and a number of the improved classifying units may be arranged inparallel as shown in Fig. 5 so that all of the fines may be delivered to a common conveyor through the outlet openings 21 of the launders 25. If so desired, a number of the units may be arranged in series so that the separated materials delivered from each unit may be further treated in succeeding units, and the degree of treatment and the quantity of material handled may thus be varied throughout a considerable range by providing a suitable number of the improved screening devices.

While the relatively 'shallowsyphon section-24 may be entirely suitable for certain classes of material, other materials may require the use of a deeper syphon section 24' as shown in Fig. 6, or a still deeper syphon section 24" as illustrated in Fig. 9. The inclination of the bottom 22 of the lower pulsating chamber should also be varied to suit the particular materials be varied without affecting the-position of the pulsator, and undesirable vibrations will not be type of pulsating unitalso facilitates erection and maintenance and may be manufactured at relatively moderate cost. The immersion of these bellows pulsating plungers within the accepted stock chamber, alsopermitsztransmission o! the pulsations with minimum wave dispersion, and as previously indicated, the fiexible connection i2 may be utilized with the bellows type plunger unit as'well as with the piston type pulsator.

Most efiicient distribution of the pulsations within the screening zone may also be efiected by adjusting the distribution vanes 30, thereby enhancing the flexibility of the improved assemblages, and the adjustable weirs 26 co-operating with the syphon sections 24 and with the sloping bottoms 22 of the lower chamber l8, en-

able most efiicient delivery of the treated stock without undesirably affecting the pulsations through the screen decks. The present improved classifying device is entirely. automatic in operation except for the several adjustments which may however be made without interfering with the normal operation of the machines.

It should be understood that it is not desired to limit this invention to the exact details or construction or to the precise mode of use, herein shown and described, for various modifications within the scope of the claims may occur to persons skilled in the'art.

I claim:

1. In combination, an approximately rectangular casing having pul feed and discharge of independent screen plates disposed in approximately the same plane above said lower chambers and coacting with said casing to provide a continuous upper chamber between said feed and discharge launders, a 'pulsator communicable with the deeper ends of all of said lower chambers and being oper'ableto produce liquid pulsations therein, adjustable gates for varying the fiow of pulsating liquid with respect to said lower chambers, and independently adjustable weirs interposed .at the shallower ends oi. said chambers disposed in series along one side of the casing and their shallower ends disposed in like series along the other side of the casing, said casing also having an elongated duct in open communication with all of said shallower chamber ends and a liquid collecting launder extending along its side adjacent to said duct, a series of independent screen plates disposed in approximately the same plane above said lower chambers and coacting with said casing to provide a continuous upper chamber between said feed and discharge launders, a pulsator communicable with th deeper ends of all of said lower chambers and being operable to produce liquid pulsations therein, means for varying the amplitude of the pulsations produced by said pulsator, pivotally adjustable gates cooperable with said partitions to vary the flow or pulsating liquid with respect to said lower chambers, and independently adjustable weirs interposed at the shallower ends of said chambers between said duct and said liquid collecting launder.

3. In combination, an approximately rectangular casing having pulp feed and discharge launders at its opposite ends and a series of partitions between said launders dividing the intervening space into transverse gradually enlarging similar lower chambers having their deeper ends disposed in series along one side of the casing and their shallower ends disposed in like series along the other side of the casing, said casing also having an elongated duct in open communication with all of said shallower chamber ends and a liquid collecting launder extending along its side adjacent to said duct, a series of independent screen plates disposed in approximately the same plane above said lower chambers and meeting with said casing to provide a continuous upper chamber between said feed and discharge launders, a pulsator communicable with the deeper ends of all of said lower chambers and being operable to produce liquid pulsations therein, a flexible liquid conduit interposed between said pulsator and said casing for permitting variation in the inclination of said plates and said chambers, adjustable gates for varying the flow of pulsating liquid with respect to said lower chambers, and independently adjustable weirs interassaevo posed at the shallower ends or said chambers between said duct and said liquid collecting launder.

4. .In combination, an approximately rectangular casing having pulp feed and dischange launders at its opposite ends and a series of partitions between said launders dividing the intervening space into transverse gradually enlarging similar lower chambers having their deeper ends disposed in series along one side oi the casing and 7 their shallower ends disposed in like series along the other side of the casing, said casing also having an elongated duct the bottom or which is in open communication with the-lowermost portions of all of the adjacent shallower chamber ends and a liquid collecting launder extending along its side adjacent to said duct, 9. series of interchangeably similar independent screen plates disposed above said lower chambers and coasting with said casing to provide a continuous upper chamber between said feed and discharge launders, a pulsator communicable with the deeper ends of all of said lower chambers and being operable to produce liquid pulsations therein, adjustable means for varying the flow of pulsating liquid with respect to said lower chambers, and a flexible liquid conduit interposed between said pulsator and said casing for permitting variation {:3 the inclination of all of said plates and cham- 5. In combination, an approximately rectangular casing having pulp feed and discharge launders at its opposite ends and a series of partitions between said launders dividing the intervening space into transverse gradually enlarging similar lower chambers having their deeper ends disposed in series along one side of the casing and their shallower ends disposed in like series along' the other side of the casing, said casing also having an elongated duct in open communication with all of said shallower chamber ends and a liquid collecting launder extending along its side adjacent to said duct, a series of interchangeably similar screen plates disposed in approximately the same plane above said lower chambers and coacting with said casing to provide a continuous upper chamber between said feed and discharge launders, a pulsator communicable with the deeper ends of all or said lower chambers and being operable to produce liquid pulsations therein, and a series of independently adjustable weirs interposed between said duct and said liquid collecting launder ad