US3780645A

US3780645A - Screw press assembly

Info

Publication number: US3780645A
Application number: US00277248A
Authority: US
Inventors: J Farmer
Original assignee: Ward Foods Inc
Current assignee: Ward Foods Inc
Priority date: 1972-08-02
Filing date: 1972-08-02
Publication date: 1973-12-25
Anticipated expiration: 1990-12-25

Abstract

A screw press assembly for expressing juice from bagasse and other disintegrated juice-containing material, having an upwardly opening hopper feeding a plurality of barrels, through each of which bagasse is driven by a screw extending into the hopper, and means in the inlet of the hopper for preventing accumulation of the material in advance of and distributing it uniformly over the screws. Within the barrels, the screws are so constructed as to produce a relatively low radial force and concentrate the pressure at the barrels'' outlets and that pressure is controlled by axially shiftable, fluid-actuated plugs in the outlets. The barrels have bell-mounted inlets for minimum interference with entry of the material and are perforated throughout their lengths for passing expressed juice and the screws are intergeared for driving all through a drive connected to one.

Description

United States Patent Farmer Dec. 25, 1973 SCREW PRESS ASSEMBLY 453,274 3/1913 France lOO/l46 l4, 100 14 [75] Inventor: John Farmer, Honolulu, Hawan 1 0 605 6/l952 France 6 [73] Assignee: Ward Foods, Inc., New York, N.(.

Primary Examiner-Peter Feldman [22] Filed: 1972 Att0rneyWilmer Mechlin [21] Appl. No.: 277,248

Related U.S. Application Data [63] Continuation-impart of Ser. No. 65,447, Aug. 20, [57] ABSTRACT 1970, abandoned.

'A screw press assembly for expressing juice from ba- [52] U.S. C1. 100/117, 100/147 gasse and other disintegrated juice-containing mate [51 Int. Cl B30b 9/12 rial, having an upwardly opening hopper feeding a plu- [58] Field of Search 100/117, 127, 145, rality of barrels, through each of which bagasse is 100/146, 147, 148, 149, 150 driven by a screw extending into the hopper, and

means in the inlet of the hopper for preventing accu- [56] References Cited mulation of the material in advance of and distributing UNlTED STATES PATENTS it uniformly over the screws. Within the barrels, the 332,718 12/1885 Lafferty 100/145 x i l f mmgucted as to prfiduce relat'vegy 585,800 7 1897 Toulouse et 1 100/147 x Concentrate} 6 Pressure at t F 775327 11/1904 Ketelsen A 100/127 x barrels outlets and that pressure 18 controlled by ax1- 1,152,857 9/1915 Stehlin 100/148 y Shlftable, fluid-actuated p g m the Outlets The 1,855,369 4/1932 Tessandori 100/147 barrels have bell-mounted inlets for minimum interfer- 3,070,005 12/1962 Kemp etal. 100/146 ence with entry of the material and are perforated 3,432,344 3/l969 Farmer 100/147 throughout their lengths for passing expressed juice 34701815 0/1969 Jung 100/146 X and the screws are intergeared for driving all through 1,443,535 l/l923 Holmquist lOO/l45 UX a drive connected to one FOREIGN PATENTS OR APPLICATIONS 727,030 3/1955 Great Britain 100/117 31 Claims, 11 Drawing Figures PATENTED UECZS I975 SHEET20F9 PATENTED DEC 25 I975 SHEEISII9 SCREW PRESS ASSEMBLY This application is a continuation-in-part of my copending application Ser. No. 65,447, filed Aug. 20, 1970, now abandoned.

BACKGROUND OF THE INVENTION Farmer U.S. Pat. No. 3,432,344, issued March 11, 1969, discloses for expressing liquid from disintegrated juice-containing material a multi-barrelled screw press having a common feed hopper and shiftable plugs at the outlets of the barrels for regulating the pressure therein. It has now been discovered that the material entering the feed hopper of a press, such as there disclosed, tends to accumulate in and, when bagasse, to bridge across the hopper above the screws, with consequent impairment of the operation of the press. Also, as pointed out in A. W. French U.S. Pat. No. 3,195,446, issued July 20, 1965, it has generally been considered necessary, in adapting a screw press for extracting liquid from bagasse, to use presses of very heavy construction and high power requirements. It is with these problems, among others, that the present invention is concerned.

SUMMARY OF THE INVENTION The primary object of the present invention is to provide an improved screw press assembly for expressing juice-containing liquid from bagasse and other disintegrated juice-containing material, combining a screw press having a plurality of barrels individually fed by screws from a common feed hopper and a plurality of rotary members in the path of the material in advance of the screws and having radial arms and longitudinal ribs on their shafts for preventing the material from accumulating in the hopper and on their shafts and distributing the material among the screws.

Another object of the invention is to provide an improved screw press for expressingjuice from disintegrated juice-containing materials combining a pluralbarrelled screw press and rotary members in advance of the screws, wherein the barrels are perforated substantially throughout their lengths for passing expressed liquid and the screws within the barrels are so constructed as to concentrate the pressure at plugregulated outlet orifices of the barrels and apply relatively low pressures to the barrels in advance of the orifices, thus enabling the barrels to be of light-weight construction and minimizing the required power.

An additional object of the invention is to provide an improved screw press assembly for expressing juice from disintegrated juice-containing material, wherein the press is plural-barrelled and the barrels have flared inlets onto a common feed hopper for minimum interference with driving of the bagasse into the barrels.

A further object of the invention is to provide an improved screw press assembly for expressing juicecontaining liquid from bagasse which is capable of handling bagasse of high liquid content and combines lightweight construction and high capacity with low power requirements.

In the preferred embodiment, particularly designed for bagasse, the screw press assembly has a common feed hopper feeding bagasse to a plurality of laterally spaced cylindrical barrels having bell-mouthed inlets and foraminous walls. The bottom of the hopper is also foraminous to pass liquid and is convoluted to conform with a close fit to the undersides of the overlying portions of the screws. The shafts of the screws extend through the barrels and the hopper and are journalled therebeyond at both ends and intergeared ahead of the hopper so that all can be driven in desired directions by a drive connected to one of the shafts.

Within the hopper and the inlet of the related barrel, the rib of each screw increases progressively in pitch toward its trailing end and is fixed to a hub keyed to the shaft and formed of cylindrical sections of progressively decreasing diameter toward that end. Inside the barrel the hub of each screw also is formed of abutting sections keyed to the shaft and having forwardly tapered conical lead portions merging with cylindrical trailing portions. A screw flight or rib section is mounted on the trailing portion of each barrel hub section. Each flight preferably has a sharp leading edge and, if desired, any of the flights, and particularly those adjacent the outlet ends of the barrels, may be of increased pitch at their trailing ends.

Fluid-loaded, conical plugs in the outlet ends of the barrels and shiftable relative thereto on stationary slides internally journalling rear ends of the screw shafts, regulate the pressure in the barrels. Due to the shapes of the hub sections and screw flights in the barrels, the pressure, while increased in stages in the barrels, is mainly concentrated at their outlet ends and radial pressure on the barrels is low. Consequent upon that low pressure, the barrels are relatively thin-walled and enabled to have hinged gates at the top for ready access to their interiors. Flat breaker bars fixed to the doors instand in advance of each flight and are inclined in the direction of spiral movement of the bagasse to prevent the latter from turning with the screws but with minimum impedence to its movement.

At the inlet end of the preferred press assembly, a plurality of rotary members rotatably mounted in the inlet of the hopper above and parallel to and driven off the screws, prevent the entering bagasse from bridging across the hopper above the screws, and also on their own shafts, while distributing it uniformly among the screws. At the assemblys outlet end the outlet ends of the barrels have hoods cooperating with paddles adapted to turn downwardly between the slides for preventing the discharged bagasse from building up thereon.

The foregoing and other objects and features of the invention will appear hereinafter in the detailed description, be particularly pointed out in the appended claims, and be illustrated in the accompanying drawings, in which:

FIGURE DESCRIPTION FIG. 1 is a side elevational view of a preferred embodiment of the screw press assembly of the present invention showing the assembly connected for a supply of bagasse to the outlet end of a rinsing hopper;

FIG. 2 is a longitudinal sectional view taken along lines 2-2 of FIG. 1;

FIG. 3 is a fragmentary sectional view on an enlarged scale taken along lines 33 of FIG. 1;

FIG. 4 is a fragmentary transverse sectional view on a further enlarged scale, taken along lines 4-4 of F IG. 1 and showing one of the barrels with the screw removed;

FIG. 5 is a fragmentary transverse sectional view on the scale of FIG. 4, taken along lines 5-5 of FIG. I;

FIGS. 6, 6A and 6B are together a composite longitudinal sectional view on the scale of FIG. 4, taken along lines 6-6 of FIG. 2 with the reduction gear removed;

FIG. 7 is a fragmentary horizontal sectional view on the section and scale of FIG. 3, showing an alternate form of chopper rolls;

FIG. 8 is a fragmentary vertical sectional view taken along lines 8-8 of FIG. 7, and

FIG. 9 is a fragmentary vertical sectional view on an enlarged scale taken along lines 9-9 of FIG. 7.

DETAILED DESCRIPTION Referring now in detail to the drawings in which like reference characters designate like parts, the improved screw press assembly of the present invention, while adapted for use on other disintegrated juice-containing material, in the preferred embodiment, is particularly designed for expressing sugar juice from previously disintegrated sugar cane, commonly known as bagasse, and will be so described as exemplary of the invention.

Designated as 1, the improved screw press assembly is comprised of a screw press 2, preferably sloping upwardly toward its outlet end 3 and mounted on a correspondingly sloping base 4. The screw press 2 has at its inlet end 5 a feed hopper or casing 6 into which is introduced, delivered or fed the bagasse or other disintegrated juice-containing material from which liquid containing juice is to be expressed or extracted. The feed hopper 6 preferably will be upwardly or top opening for receiving bagasse through its upper or top 7. If, as illustrated, the assembly 1 is used for expressing liquid from bagasse previously rinsed with water or other diluent in a downwardly discharging rinsing hopper 8, generally of the type disclosed in Farmer U.S. Pat. No. 3,432,344, the feed hopper 6 conveniently is connected at its upper end 7 to and open upwardly into the rinsing hopper. As the bagasse usually will be introduced or delivered in a sloppy wet condition, the preferred feed hopper 6 has a foraminous or perforated bottom 9 through which excess liquid can drain into an underlying sump 10.

Opening rearwardly into and projecting forwardly from the otherwise closed front end or wall 11 of the feed hopper 6, are a plurality or multiplicity of parallel, radially or laterally spaced and aligned barrels 12, the number of which in a given installation will depend largely on the desired capacity but usually will be a multiple of two, such as the illustrated four. Preferably closely spaced and connected to or opening onto the feed hopper 6 through relatively short bell-mouthed inlets, entrances or inlet or entrance tubes 13, for both facilitating entry of the bagasse from the feed hopper and minimizing blockage by the hoppers otherwise closed rear wall 11, the barrels 12, beyond the inlets, preferably are cylindrical and of uniform inside diameter to their outlet ends 14, although, if desired, these ends may be flared or bell-mouthed. As opposed to the usual heavy construction typified in French U.S. Pat. No. 3,195,446, the barrels 12 and their bell-mouthed inlets 13, for the reasons hereinafter to be pointed out, can be and preferably are of light-weight construction and relatively thin-walled, a wall thickness of as little as inch being suitable for both, in conjunction, over the barrels proper, with axially spaced, annular, external or encircling, reinforcing bands or ribs 15.

For driving bagasse from the common feed. hopper or chamber 6 through the barrels 12 and their inlets 13 and in process expressing therefrom juice or juice- 'containing liquid, there are provided a plurality of screws 16, one for each barrel. In the preferred construction, each screw 16 has a solid central shaft or spindle 17, which extends through both the related barrel and inlet and the common feed hopper 6, and, beyond the barrel and hopper, is journalled at or adjacent opposite ends in suitably housed bearings 18 supported by the base 4. Conveniently keyed or otherwise fixed against relative rotation to each screw shaft 17, within the opposite ends or longitudinal confines of the feed hopper, barrels and inlets, is a hub 19 mounting and having secured thereto the helical blade, rib or vane 20 or the screw. The blade 20 of the screw 16, although extending substantially the combined length of the feed hopper and related barrel, is divided into two main parts, one a continuous leading or hopper part 21 extending from substantially the front end or wall 22 of the feed hopper through the inlet 13 to the barrel 12 and of progressively increasing pitch toward its trailing end and the other an interrupted trailing or barrel part 23 contained in and extending substantially the length of the barrel end formed ofa plurality of axially or longitudinally spaced flights 24, each preferably subtending an arc of less than 360.

The leading or hopper part 25 of the hub 19 of each screw 16 in the hopper 6 and barrel inlet 13, mounting the continuous part 21 of the blade 20, is formed of abutting cylindrical sections 26 of progressively decreasing diameter toward the barrel. The trailing or barrel part 27 of each hub 19 contained in the related barrel also preferably is formed of abutting sections 28. However, these barrel hub sections 28 have forwardly tapering conical or more precisely, frusto-conical, leading portions 29, each merging rearwardly with a cylindrical trailing portion 30. Abutting at the front the rear end of the hopper hub part 25, the barrel hub part 27 extends from substantially the front end of the barrel toward but terminates short of or inside the barrels outlet end 14.

As opposed to those of the hopper part 25, the sections 28 of the barrel part 27 of each hub 29 are of progressively increasing diameter toward the outlet end 10 of the barrel l2 and at each end each conical portion 29 is of the same diameter as the adjoining or contiguous cylindrical section 26 or portion 30. Consequently, the free annular area within the barrel 12 about the hub 19 decreases toward the barrels outlet end 14 in successive but separate or spaced stages, the decreases occurring over the conical portions 29 and the separations being provided by the intervening cylindrical portions 30.

For driving bagasse or other juice-containing material through each barrel 12, one of the flights 24 of the interrupted barrel part 23 of the blade 20 is mounted on or fixed to each of the barrel hub sections 28. In the preferred construction, each flight partly surrounds or encircles and is axially or longitudinally contained by and coextensive with the cylindrical trailing portion 30 of its hub section. As illustrated, each flight 24 should have a sharp forwardly turned leading edge 31 and be of increased pitch over its trailing end portion 32, with the increase relatively slight and purposed to add impetus for driving the bagasse over the following conical portions 29 in the case of the leading and intermediate flights, but sharp and extending substantially over its rear half in the case of the rear or trailing flight to provide maximum driving force in the vicinity of the barrels outlet end 14. With the leading and intermediate flights so formed and the tapers of the conical leading portions 29 also preferably relatively slight or small, on the order of 5 inches in the illustrated embodiment, the increases in pressure within the barrel are correspondingly small except in the vicinity of its outlet end 14.

The division of the blade within each barrel 12 into axially spaced flights 24, each mounted on a cylindrical portion 30 and preceded by a forwardly tapered conical portion 29, not only divides the pressure increase into a plurality of separated stages or steps, but also provides in advance of each flight an interruption or gap for accommoadting means for'inhibiting the tendency of the bagasse being driven through the barrel to rotate with the screw. The preferred inhibiting means is a plurality of flat breaker bars 33 each fixed or secured to and instanding radially from the barrel 12 toward and axially within the conical portion 29 in advance of one of the flights 24 and sharp-edged at the front and inclined in the direction of helical movement of the bagasse. Conveniently, these breaker bars 33 are all mounted on a hinged or otherwise removable gate 34, permitted by the relative low pressure on the barrel in advance of the rear part of the trailing flight 24 to form the top portion of the barrel from the leading portion thereof into the forepart of that flight and normally closing an opening 35 of corresponding dimensions through which access can be had to the interior of the barrel for inspection and any necessary repair or maintenance.

For controlling or regulating the pressure within the barrels l2 and enabling the bagasse driven therethrough to be extruded therefrom in a relatively dry condition, each barrel has in its outlet end 14 an axially shiftable plug 3 defining or bounding with'that end an annular extrusion orifice 37 of variable area depending on the plugs axial position relative to the opening. For fine control of the area of the extrusion orifice 37, the plug 36 is conical and forwardly tapering and fits in a correspondingly inwardly tapered or outwardly flared bevel 38 in the barrels outlet end 14. Sharp-edged at the front, the preferred plug 36 is annular or axially bored and rides or slides on a stationary tabular slide or guide 39 extending into the outer end of the barrel substantially to and of substantially the outside diameter of the trailing or adjoining barrel hub section 28. The slide 39 projects for some distance forwardly from the barrel and, therebeyond, is stationarily mounted on a mounting bracket 40 fixed to and upstanding from the base 4 and connected by a tie bar 41 to a fixed end plate 42 supporting the outer end of the barrel on the base.

rigidly supported, the tubular slide 39 not only slidably mounts the plug 36 on its exterior but receives and journals in its interior the rear end portion of the screw shaft 17 extending beyond the barrel. in this case the end portion of the shaft preferably is journalled in a spaced pair of the end bearings 18, one an outer thrust bearing at its outer end, and the other an inner roller bearing adjacent the outer end of the barrel. By

suitably locking the roller bearing in place and interposing a suitable packing and follower assembly 43 between the inner roller bearing and the adjoining end of the rear or trailing barrel hub section 28, the slide both has its interior sealed against entry of liquid and is enabled to hold the several hub sections against axial movement on the shaft.

For shifting the plug 36 on the slide 39, either with or against the relatively dry bagasse extruded through the orifice 37, a fluid cylinder unit 44 is mounted on the outer side of the mounting bracket 40 beyond and concentric or coaxial with the outer end of the slide 39. The pressure range required in a particular installation will determine whether the cylinder unit 44 should be actuated hydraulically or by air pressure. However, ordinarily, compressed air actuation will suffice and, as illustrated, the unit 44 can have its piston 45 fixed to the mounting bracket 48 with its cylinder 46 extending outwardly therefrom and relatively movable axially under fluid actuation. Thrust rods 47 secured to the cylinder 46 and extending through the mounting bracket 40, are secured forwardly thereof to an annular follower or bearing ring 48 slidably mounted on the slide 39 and acting forwardly against the back of the plug 36 through a connecting sleeve 49 sliding on the slide and fixed at the front to the plug and backed at the rear by the follower.

As mentioned eariler, there preferably are one or more pairs of the barrels 12, each having or containing a drive screw 16 extending forwardly into and substantially the length of the feed hopper 6. The main reason for this preference of an even number of barrels and screws is that it enables the screw press to have one or more pairs of counter-rotating screws with consequent counterbalancing of their torques and reduction in the strength and weight of the structure required for their support. The desired counter-rotation of the screws of each pair suitably is achieved by extending their shafts l7 forwardly beyond the feed hopper 6 into a gear box 50 and, within the latter, fixing to each shaft one of a plurality ofintermeshing gears 51, each sandwiched between or straddled by a pair of bearings mounted in the front and rear walls 52 of the gear box and, collectively, severing as the end bearings 18 journalling the shafts front ends.

The intermeshed gears 51 are driven by a common power source by further forwardly extending the shaft 17 of one of the middle or inboard screws 16 and connecting it by a primary coupling 53 to the output shaft 54 of a gear reducer 55, preferably with the screw shaft split and connected by a secondary shear or shear pin coupling 56 between the main coupling and the gear box, in case of a jam in the screw press. In turn, the gear reducer 55 is connected on its input side to a power source, suitably a steam turbine 57. Although a turbine with its inherent fluid-coupling action needs none, if a non-slip power source is used, it is preferred to connect such a source to the gear reducer 55 through a conventional air or mechanically actuated clutch (not shown), for enabling the press assembly 1 to be stopped at any time without stopping the source or breaking the shear coupling 56.

While the screws of the outer or outboard pair adjacent the sides 58 of the hopper can each turn or rotate either upwardly ordownwardly toward the adjoining side, the former is preferred for optimum feed of bagasse from the common feed hopper 6 into the barrels 12. Accordingly, the shaft of the middle or inboard screw connected to the turbine 57 is arranged to be turned or rotated thereby in a direction that will produce the desired turning direction in the outboard screws. Thus, with the four screws of the illustrated embodiment and the middle gear on the right side of the box the drive gear driven by the power source, the several gears 51 from left to right, as viewed from the rear in FIG. 5, will rotate respectively clockwise, counterclockwise, clockwise and counter-clockwise, and their screws 16 will be right or left-handed, as appropriate, for driving the bagasse into and through the barrels.

lf fed or lead directly to the screws 16 when introduced or discharged into the feed hopper 6, the juicecontaining material will tend to accumulate in the hopper in advance of the screws and interfere with further feeding and bagasse in particular ordinarily will bridge across the feed hopper in advance of or above the screws and thereafter clog the screw press 2 by blocking ingress or access to the screws of further bagasse, This capability or tendency of the entering material is avoided or inhibited in the improved assembly by combining with the screw press clearing and distributing means for preventing the entering material from accumulatingin the hopper in advance of and distributing it among the screws. For bagasse, that means suitably is a plurality of chopper rolls or members 59. Mounted in the feed hopper 6 above or on the inlet or feed side of the screws 16, for rotation about axes parallel to those of the screws, the chopper rolls 59, in number, most suitably will be the same multiple of two as the screws.

Each chopper roll has a shaft 60 extending through and journalled beyond the rear and

front walls

11 and 22 of the feed hopper 6 and, within those walls, has mounted on and keyed or otherwise fixed against relative rotation to the shaft a plurality of projecting choppers 61 Laterally spaced, axially of the shaft 50, and circumferentially spaced or angularly related, the choppers 61 are each formed of a preferably flat, trapezoidal and outwardly tapered arm 62, disposed and extending radially of the shaft, and a tangentially disposed or tangential blade or chopping element 63 fixed to the outer end of'the arm. Each blade 63 preferably is flat and pointed at one end, with its pointed end 64 projecting or extending tangentially beyond the leg in the direction of rotation of the chopper roll 59 of which it is a part. With their shafts 60 suitably laterally aligned, as well as parallel, the chopper rolls 59 each have their choppers 61 axially staggered relative to and radially overlapping or intermeshing with those of any adjoining chopper roll. Chain-and-sprocket or like suitable drives 65 drivably connecting the chopper shafts 60 to screw shafts l7, conveniently between the feed hopper 6 and the gear box 50, enable each chopper roll 59 to be driven by or off a screw 16 and, as illustrated, preferably individually driven by the underlying or adjoining screw. Thus, with the preferred individual drive, each chopper roll 59 will rotate or turn in a direction counter that of its drive screw and also any adjoining chopper roll and the chopper rolls, collectively, will be self-cleaning.

With their intermeshing choppers 61, the chopper rolls 59 not only break up the bagasse introduced into the feed chamber 6 and effectively prevent any bridging thereof, but also serve as a positive feed for feeding the bagasse to and distributing it substantially uniformly among the underlying screws 16. ln turn, the progressive decrease in diameter and increase in pitch toward the barrels 12, respectively of the cylindrical hub sections 26 and continuous hopper parts 21 of the blades in the feed hopper 6, enable the parts of the screws 16 receiving the introduced bagasse directly from the chopper rolls 5? to withdraw the bagasse substantially uniformly over the length of the feed hopper 6 in driving or forcing the bagasse into the barrels. ln this uniform feeding action the parts of the screws in the feed hopper are assisted by convoluting the foraminous bottom of the hopper to conform substantially to the contours of the undersides of the overlying parts of the screws 16 and provide for each screw a close-fitting circularly concave trough 66.

While, in the above-described first form, the radial arms 61 of adjoining chopper rolls 59 intermesh and all of the arms have blades 63 on their outer ends, neither the intermeshing relationship nor the blades are essential for enabling the chopper rolls to perform their intended functions of preventing the bagasse from bridging. in the feed hopper 6 in advance of or above the screws 16 and distributing the bagasse among the screws instead, as in the alternate form shown in FIGS. 7-9, the chopper rolls or rotary members 59 can perform these functions with straight radial arms of such length and so disposed as to sweep the bagasse away from and prevent it from sticking to corners and sides of the feed hopper. For that matter, at the expense of some reduction in the effectiveness of the distribution among the screws, just a pair of chopper rolls at opposite sides of the feed hopper 6 and sweeping the corners and these sides will usually be sufficient to prevent the bagasse from bridging in the feed hopper. The arms 61 must be strong enough to resist bending or breaking when acting on the bagasse and can be of any crosssection suitable for this purpose, such as the lateral elongation normal to their rotative axes employed in both of the illustrated forms.

Although the chopper or agitator arms 61 of either form are effective to prevent the bagasse from bridging on walls of the feed hopper 6, so pronounced is the tendency of bagasse to bridge on any obstruction interrupting its movement that the shafts 60 between the arms are themselves not immune to bridging unless somehow protected. A suggested solution for this problem is shown on some of the chopper rolls illustrated in the drawings of the original US. Pat. application Ser. No. 65,447, but without any explanatory text. The solution, here applied to all of the chopper rolls of both forms, is to interrupt the otherwise smooth shafts 60 not only between the arms 61 but over substantially the entire length of their portions exposed within the feed hopper to the bagasse, by radially projecting ribs or projections 78 extending longitudinally of and integral or rigid with the shafts.

So long as it collectively covers the part exposed to the bagasse, the rib or ribbing '78 for each shaft 60 need not be continuous. Thus, as in both of the illustrated forms of chopper rolls 59, the ribbing 78 for a given shaft may include non-aligned or relatively circumferentially offset sections 79 each extending between an adjoining pair of arms and serving as a longitudinal spacer for those arms as well as to protect the intervening part of the shaft from bridging. In the alternate or second form shown in FIGS. 7-9, th exposed portion of the shaft of each chopper roll'within the feed hopper is a sleeve or sheath 80 sheathing or covering an inner part of the shaft and conveniently constructed of pipe or tubing split in half, with each half 81 mounting a pair of the arms 61 and the connecting or adjoining rib section 79, and the rib sections of the two halves longitudinally overlapping. Additional ribbing, in this case continuous, is provided by radial projecting side flanges 82 on opposite sides and extending the length of each half through which the halves are pinned or otherwise suitably joined together, the construction being completed by keying or otherwise fixing the sheathing 80 against relative movement to the inner or sheathed part of the shaft.

For preventing bagasse from accumulating in the feed hopper between adjoining screws, adjoining troughs 66 preferably are connected by longitudinally extending bars 67. As suited to its position and the directions of rotation of the pair of screws between which it is interposed,each bar 67 preferably presents to the bagasse from the chopper rolls 59 received between the screws a surface that is either sloping or flat. A slopingsurfaced bar thus may be inserted between a pair of screws there turning downwardly toward each other for wiping against one and directing or deflecting bagasse toward the other of the screws, while a flat-surfaced bar is appropriate between a pair of screws there turning upwardly toward each other for substantially blocking further downward progress of the bagasse and also extending a wiping action on the edges of both screws. To facilitate cleaning of both itself and the screws, the foraminous bottom 9 preferably is bolted or otherwise releasably attached or secured to the upper part of the feed hopper 6.

The tendency of bagasse to bridge across the feed hopper 6 above the screws 16 in the absence of the chopper feed 59 is but one of its unique characteristics. Even though previously disintegrated, the bagasse entering the feed hopper 6 has the same components as sugar cane, one, long flexible fibers that under certain conditions can bind together into rope-like masses, and the other, soft pith material that is one of the most absorbent materials known. In addition to these inherent components, the entering bagasse also will contain sand, dirt and trash in amounts that depend on the special growing, harvesting and cane preparation machinery or techniques used on the plantation where the particular sugar cane is grown.

Pith represents about 40 percent of the weight and a much larger percentage of the volume of the bagasse and contains most of the liquid. The pith is easily compressed, but only if its liquid content is free to escape, and also tends to trap sand and abrasive fiber which can cause rapid wear at pressure points. By contrast with the pith, the fiber has high frictional characteristics and in rope-like masses can have a brakeband effect. On the other hand, when the bagasse is compressed, the fiber acts as a filter medium to restrain escape of particles of pith with the liquid and also provides an open structure in the bagasse through which the liquid can move. Although the fiber is long and tough, neither it nor the pith is hydraulic in nature and, given freedom of escape of the liquid content, axial pressure applied to bagasse in a restraining cylinder will not be applied as a radial force to the cylinders wall. It is these unique characteristics of bagasse, heretofore not fully appreciated, that have been availed of collectively in developing the preferred embodiment of the press 2 of the improved screw press assembly 1 of the present invention.

The preferred screw press assembly can handle bagasse received in a sloppy wet condition, with a possible moisture or liquid content in excess of 96 percent when the assembly is connected to the rinsing hopper 8 and the feed hopper 6 is used in a final rinsing stage. Within the feed hopper 6, the bagasse is not radially restrained and the foraminous bottom serves mainly to enable excess liquid to drain by gravity into the underlying sump 10 before the bagasse enters the inlets 13 of the barrels 12. However, the bagasse is under radial restraint when it enters the inlets 13 and the restraint continues until the bagasse has been extended through the orifices 37 at the outlet ends 14 of the barrels 12. The screw press 2 is designed only to press liquid from the bagasse but this objective cannot be achieved without enormous strength in both the inlets and the barrels, unless liquid pressed from the bagasse is free to escape and thus prevented from causing the bagasse to act hydraulically as a liquid medium. It therefore is vital that the inlets and barrels permit ample radial drainage of the expressed liquid throughout their lengths, not

i only to minimize the hydraulic effect in both, but in the case of the inlets, to prevent the then largely liquid bagasse from being forced back into the feed hopper 6 with consequent reduction in the capacity of the press.

Due to the filter action'of the fiber, the inlets and barrels can have drain holes or openings 68 as large as about 7/16 inches diameter without expressing substantial quantities of pith with the liquid and in the preferred embodiment such holes are so closely spaced as to cover over 15 percent of the areas of the inlets and barrels presented to the bagasse. In addition, by being bell-mouthed and covering almost the entire width of the rear wall 11 of the feed hopper 6, the inlets 13 direct or funnel the bagasse into the barrels 12 with minimum obstruction by that wall, while permitting the barrels to be so laterally or radially spaced as to accommodate therebetween both the necessary reinforcing structure and drainage of the expressed liquid into the underlying sump 10.

In the barrels 12 the pressure on the bagasse increases in stages as it passes over the conical hub portions 29, but if, as preferred, the taper or inclination of these portions is only about 5, the pressure increases are relatively small and the radial forces on the barrels correspondingly low. The pressure on the bagasse as it is extruded through the extrusion orifices 37 at the outlet ends 14 of the barrels in the final stage of the pressing, is much higher. But even when the press is used in place of the customary two or three mills for final drying of the bagasse to a moisture content of less than 50 percent, the pressure applied in this final stage ordinarily will not exceed 8,000 lbs. p.s.i. When, instead, the extruded bagasse is to be further processed for juice, as in another rinsing hopper 8 or one or more roll mills, its moisture content will be higher, and the pressure in the final pressing stage will be reduced correspondingly.

With the pressure exerted on the bagasse in the barrels thus concentrated at the outlet orifices 37 and the latter backed on the barrel sides by the end plate 42, the barrels themselves can be relatively thin-walled, a thickness of some inches in the preferred stainless steel plate usually sufficing, and require relatively thin reinforcing bands 15. Accordingly, but contrast with the heavy barrel construction in French Pat. No. 3,195,446, and the correspondingly large spacing between barrels that such construction would require if applied to a plural-barrel press, in the improved press of this invention a barrel spacing of about 5 inches will be more than ample to accommodate both the reinforcing bands and expressed liquid. Too, since requiring only a few pressure stages within the barrels, the illustrated three ordinarily sufficing, the barrels can be and preferably are relatively short, the preferred length being about three feet. In inside diameter, the preferred range of the barrel is 12 inches to l6 inches, with the selection within that range determined by the per barrel capacity desired in a particular installation.

As mentioned earlier, the spaced flights 25 of the screws 16 within the barrels 12 are of increased pitch over their trailing end portions to assist in driving the bagasse through the following succeeding pressure stages and have sharp leading edges, the latter for the purpose of cutting or breaking up any rope-like masses of fiber in the bagasse. The breaker bars 13 also have sharp leading edges for the same purpose and, by being flat and inclined in the direction of helical movement of the bagasse, prevent any fiber masses clinging to those edges from interfering with that movement. As in previous presses, the main function of the breaker bars is to provide the bagasse from turning with the screws 16 and the illustrated bars instand substantially to the adjoining barrel parts 27 of the hubs l9. Normally this optimum length will be unnecessary and the greater friction exerted against the outside of the bagasse by the foraminous barrels than on the inside by the smooth hubsshould suffice to prevent the bagasse from turning or spiralling with the screws and allow the breaker bars to be shortened or even eliminated, with corresponding reduction in the power required to drive the bagasse through the barrels;

Even with the breaker bars 33 of the illustrated length, the power requirements of the press assembly are low. Using barrels of 14% inches l.D. and with the screws turning at around 125 rpm, a four-barrel press can handle over 150 tons per hour of 15 percent fiber cane and reduce the moisture content of the discharged b agasse to less than 55 percent with about 350 h.p., and a six-barrel press of like capacity per barrel and capable of final drying of the bagasse to a moisture content of less than 50 percent, is estimated to require only about 500 hp. Coincidentally, the concentration of the pressures is their barrels at the outlet orifices 37, pratically reduces the maximum strength in either version to that required to withstand the torque of the screws.

With the extrusion orifices 37 annular, the bagasse discharged from the screw press 2 will be extruded in rings about the plugs 36. On discharge, the bagasse is intended to drop by gravity into an underlying chute 69, usually to a conveyor or other suitable carrier (not shown) for transport to storage or for further processing, depending on its moisture content. Since, in reaching the discharge chute 69 some of the discharged bagasse must pass between or by the hubs 36 and their tubular slides 39, the tendency of the bagasse to bridge can cause it to accumulate on and in the spaces between the slides and thus interfere with the operation of the press. The mounting bracket 49 and end plate 42 are so longitudinally or axially spaced relative to the radial or lateral spacing between the slides 39 and the output of the particular press as to provide ample area or space between the slides for accommodating any discharged bagasse that must pass therethrough to the discharge chute 69.

To prevent bridging despite the ample spacing between the slides 39 and'consequent clogging of the discharged bagasse at the outlet of the press 2, provision is made for positively driving the bagasse downwardly between the slides whenever a clogging condition occurs. This preferably is accomplished by mounting on the base 4 beyond the mounting bracket 40 a vertically rotatable paddle wheel having a horizontal powerdriven shaft 71 disposed normal to the slides and journalled in support arms 72 pivoted for vertical swinging to the base. Normally or in operative condition positioned above the slides 39 and outside and adjacent the mounting bracket 40, the shaft 71 conveniently is turned or rotated by a gear reducer 73 swingable with it on the support arms 72 and belt-driven by a stationary motor 74. Fixed to or mounted in axially spaced relation on the shaft 71 is a plurality of suitably doubleended paddles 75 each aligned longitudinally with and swingable downwardly into one of the spaces between the slides. swingable, as needed, into and out of operative position on the support arms 72, the paddle wheel 70 preferably has its paddles 75 individually hooded, as at 76 over the outer part of their path of movement to catch any bagasse that might otherwise be thrown beyond the mounting bracket 40, and the extrusion orifices 49 have a stationary hood 77 mounted about their upper part on the end plate 42 for directing or deflecting the bagasse discharged through that part into the path of the paddles 75. A

From the above detailed description it will be apparent that there has been provided an improved screw press assembly which, as applied to bagasse, is capable of receiving bagasse of any degree of wetness and requiring relatively low power and strength in its plurality of barrels for extruding the bagasse in any desired moisture content up to that of final drying. it should be understood that the described and disclosed embodiment is merely exemplary of the invention and that all modifications are intended to be included that do not depart from the spirit of the invention and the scope of the appended claims.

Having described my invention, I claim:

I. A screw press assembly for expressing juicecontaining liquid from bagasse and other disintegrated juice-containing material, comprising a feed hopper for receiving the material, a plurality of laterally spaced screws in and projecting forwardly from said feed hopper, a barrel receiving each screw beyond and opening rearwardly onto said feed hopper, an extrusion orifice at an outer end of each barrel, a shiftable plug in each orifice for determining the area thereof, and a plurality of rotary members in the path of said material fed to said hopper for preventing said material from accumulating in said hopper in advance of said screws, each of said rotary members including a rotatably mounted shaft, a plurality of arms spaced axially of and projecting radially from said shaft, and rib means on and extending substantially the length of the portion of said shaft exposed to said material for preventing said material from accumulating on said shaft.

2. A screw press assembly according to claim 1, wherein the rib means on each shaft include rib sections extending between adjoining arms on the shaft.

3. A screw press assembly according to claim 2, wherein certain of the rib sections are circumferentially offset relative to each other.

4. A screw press assembly according to claim 1, wherein the feed hopper is upwardly opening, and the rotary members are rotatably mounted in the feed hopper above the screws.

5. A screw press assembly according to claim 4, wherein the rotary members and screws are mounted for rotation about parallel axes.

6. A screw press assembly according to claim 5, including a rotary member for and vertically aligned with each screw, and wherein each rotary member is drivably connected to the screw aligned therewith.

7. A screw press assembly according to claim 6, wherein the rotary members are laterally spaced chopper members, each arm has fixed to an outer end thereof a tangential blade having a leading and projecting tangentially beyond said arm in the direction of rotation thereof, and the arms of each chopper member 10. A screw press assembly according to claim 2,

wherein the portion of each shaft exposed to the material is a sleeve split axially in half and fixed against relative rotation to and covering an inner part of the shaft, and each sleeve half mounts at least a pair of the arms and the rib section therebetween.

11. A screw press assembly according to claim 10, wherein the rib means include radially projecting side flanges on opposite sides and extending the length of each half and each connected to the adjoining flange on the other half for connecting said halves.

12. A screw press assembly according to claim 1, wherein the number of the screws is a multiple of two, the screws have shafts extending and journalled beyond opposite ends of the feed hopper and barrels, the shafts are intergeared forwardly beyond the feed hopper, and one of the shafts projects further forwardly and is drivably connected to powered drive means for thereby driving itself and the other screws 13. A screw press assembly according to claim 1, wherein the number of screws is a multiple of two, each barrel is cylindrical and opens into the feed hopper through a bell-mouthed inlet, the inlets together substantially cover the width of a rear wall of the feed hopper, the barrels and inlets are foraminous over substantially the lengths and circumferences thereof, and a sump underlies the barrels and inlets for receiving liquid expressed radially therethrough.

14. A screw press assembly according to claim 13, wherein each screw includes a shaft projecting and journalled beyond opposite ends of the related barrel and feed hopper, a hub mounted against relative rotation on said shaft and extending substantially the length of the barrel, feed hopper and related inlet, and a helical blade fixed to and substantially coextensive in length with said hub and divided within said barrel into a plurality of axially spaced flights.

15. A screw press assembly according to claim 14, wherein each barrel is internally cylindrical, each hub within the related barrel is divided into axially abutting sections each having a cylindrical trailing portion and a forwardly tapering conical leading portion, and each hub section mounts and substantially axially contains one of said flights on said cylindrical trailing portion thereof.

16. A screw press assembly according to claim 15, wherein each flight increases in pitch over a trailing part thereof.

17. A screw press assembly according to claim 15, whrein each flight has a sharp leading edge.

18. A screw press assembly according to claim 16, wherein each flight has a sharp leading edge.

19. A screw press assembly according to claim 18, including a plurality of axially spaced flat breaker bars fixed to and instanding radially from each barrel between the flights therein, said breaker bars being inclined in the direction of helical movement of bagasse through the barrel and having sharp leading edges.

20. A screw press assembly according to claim 19, wherein each breaker bar immediately following a flight has the leading edge thereof closely adjacent the trailing edge of the flight.

21. A screw press assembly according to claim 19, including a removable foraminous gate normally closing an access opening in an upper part of each barrel and mounting the breaker bars therein.

22. A screw press assembly according to claim 15, wherein the part of each screw blade in the feed hopper and related inlet is continuous and of progressively increasing pitch toward its trailing end, and the hub part of each screw mounting said continuous part of said blade is divided into a plurality of abutting cylindrical sections of progressively decreasing diameter toward the trailing part thereof.

23. A screw press assembly according to claim 19, wherein the feed hopper includes a removable foraminous bottom for draining excess liquid from the bagasse into an underlying sump before feeding thereof into the inlets to the barrels, and said bottom is convoluted to conform to the contour of the undersides of the screws and form for each thereof a close-fitting trough.

24. A screw press assembly according to claim 20, wherein adjoining troughs are connected by longitudinally extending bars, each disposed between a pair of adjoining screws, certain of said bars presenting sloping and other thereof presenting flat surfaces to juicecontaining material received between the screws for respectively directing and blocking further downward movement of the material according to the direction of relative rotation of the adjoining pair.

25. A screw press assembly according to claim 15, including a stationary cylindrical slide concentric with and extending into and projecting rearwardly beyond each barrel, said slide internally receiving and journalling the adjoining end portion of the related screw shaft and externally slidably mounting the related plug.

26. A screw press assembly according to claim 25, wherein the plug is conical and forwardly tapered and internally bounds an annular extrusion orifice in a rear end of the barrel, and including an end plate mounting and backing the rear end of the barrel over the area of said extrusion orifice.

27. A screw press assembly according to claim 26, including a mounting bracket spaced rearwardly from the end plate and mounting the stationary slide, and fluid-actuated means mounted on said mounting plate concentric with and rearwardly beyond the slide and connected to the plug for varying the area of and regulating the force applied at the extrusion orifice by applying a variable force to the plug in opposition to force applied thereto by material extruded through the orifice.

28. A screw press assembly according to claim 27, wherein the slides are laterally spaced, and including a base mounting the assembly, a discharge chute mounted on said base below the slides for receiving material discharged through the extrusion orifices, and means for positively driving discharged material downwardly between the slides.

29. A screw press assembly according to claim 28, wherein the driving means is a vertically rotating paddle wheel having a power-driven shaft positioned in operative condition above the slides and outwardly of the mounting brackets, and a plurality of paddles fixed in axially spaced relation to said shaft and each normally aligning with and turning downwardly into one of the spaces between the slides.

30. A screw press assembly according to claim 29, wherein the paddle wheel is mounted on the base for vertical swinging into and out of operative condition, and each paddle is hooded over an outer part of the path of movement thereof, and including a hood stationarily mounted on the end plate about an upper part of each extrusion orifice for directing material extruded by said part toward the paddles.

31. A screw press assembly according to claim 25, wherein each slide acts forwardly against the hub of the related screw for holding said hub against rearward axial movement on the shaft of said screw.

Claims

1. A screw press assembly for expressing juice-containing liquid from bagasse and other disintegrated juice-containing material, comprising a feed hopper for receiving the material, a plurality of laterally spaced screws in and projecting forwardly from said feed hopper, a barrel receiving each screw beyond and opening rearwardly onto said feed hopper, an extrusion orifice at an outer end of each barrel, a shiftable plug in each orifice for determining the area thereof, and a plurality of rotary members in the path of said material fed to said hopper for preventing said material from accumulating in said hopper in advance of said screws, each of said rotary members including a rotatably mounted shaft, a plurality of arms spaced axially of and projecting radially from said shaft, and rib means on and extending substantially the length of the portion of said shaft exposed to said material for preventing said material from accumulating on said shaft.

7. A screw press assembly according to claim 6, wherein the rotary members are laterally spaced chopper members, each arm has fixed to an outer end thereof a tangential blade having a leading and projecting tangentially beyond said arm in the direction of rotation thereof, and the arms of each chopper member are staggered relative to and intermesh with arms of adjoining chopper members.

8. A screw press assembly according to claim 7, wherein the screws are laterally aligned, the chopper members are aligned laterally with each other and parallel to the screws, and the screws and chopper members correspond in number.

9. A screw press assembly according to claim 8, wherein the number of the screws and the choppers is a multiple of two.

10. A screw press assembly according to claim 2, wherein the portion of each shaft exposed to the material is a sleeve split axially in half and fixed against relative rotation to and covering an inner part of the shaft, and each sleeve half mounts at least a pair of the arms and the rib section therebetween.

12. A screw press assembly according to claim 1, wherein the number of the screws is a multiple of two, the screws have shafts extending and journalled beyond opposite ends of the feed hopper and barrels, the shafts are intergeared forwardly beyond the feed hopper, and one of the shafts projects further forwardly and is drivably connected to powered drive means for thereby driving itself and the other screws.

13. A screw press assembly according to claim 1, wherein the number of screws is a multiple of two, each barrel is cylindrical and opens into the feed hopper through a bell-mouthed inlet, the inlets together substantially cover the width of a rear wall of the feed hopper, the barrels and inlets are foraminous over substantially the lengths and circumferences thereof, and a sump underlies the barrels and inlets for receiving liquid expressed radially therethrough.

24. A screw press assembly according to claim 20, wherein adjoining troughs are connected by longitudinally extending bars, each disposed between a pair of adjoining screws, certain of said bars presenting sloping and other thereof presenting flat surfaces to juice-containing material received between the screws for respectively directing and blocking further downward movement of the material according to the direction of relative rotation of the adjoining pair.