US3140652A - Dewatering press cone adjusting device - Google Patents

Description

July 14, 1964 R. M. WILLIAMS DEWATERING PRESS coma ADJUSTING DEVICE 3 Sheets-Sheet 1 Filed Feb. 2, 1962 g M UI OE m2 r 9 m9 09 A 09 NE 1|. .I ll WO mo- .50 ZEUZE E0 INVENTOR. ,qoy M/LTcWW/u/AMS y 14, 1964 R. M. WILLIAMS 3,140,652

DEWATERING PRESS CONE ADJUSTING DEVICE Filed Feb. 2, 1962 3 Sheets-Sheet 2 SOLENOID BRAKE AGTUATORS FIG.4

INVENTOR.

ROY MIL ro/v W/LLIAMS ATTORNEY y 1964 R; M. WILLIAMS 3,140,652

'DEWATERING PRESS CONE ADJUSTING DEVICE Filed Feb. 2, 1962 3 Sheets-Sheet 5 *1 Ln 2 Q 3 O m m LI. LU a: o.

l 0 34 Z n: mF- USP-- 3 gauge i 30. 0:) mm

INVENTOR.

Roy MILTON W/LL/AMS ATTORNEY 3,140,652 DEWATERING PRESS CONE ADJUSTING DEVICE Roy Milton Williams, Waynesboro, Va., assignor to E. I.

This invention relates generally to apparatus for extracting liquids from compressible masses containing liquids.

More specifically, this invention relates to an improved press apparatus for dewatering pulps, particularly to helical blade or screw type press apparatus having a mechanism for adjusting the clearance between the screw housing and the cone against which the pulp is pressed.

In pressing water and soluble by-products from pulps, such as cellulose or cellulose esters, it is usually desirable to remove as much of the liquid as possible. The final drying of the dewatered pulp by heating is made easier if most of the water is pressed out. Also, in many cases the water contains dissolved impurities, and if a large part of the water is removed by evaporation, these impurities are left in the product.

Presses of the helical blade or screw type have been used widely for such operations as pressing the juices from grapes and other fruits. These presses are used in continuous processes as contrasted to the batch operations of simple presses.

In the operation of a typical helical screw press the wet pulp is fed into one end of the press and is carried forward by a rotating helical blade toward a section of a right circular cone aligned with the axis of the blade and positioned adjacent one end of the blade with its projected vertex toward the helical blade. One of the conventional earlier types of presses is shown in FIG- URE 1 on which the various parts of the press are identified.

In this press the cone 100 is keyed to the shaft 101 so that it rotates with the shaft, but it is free to slide axially along the shaft. It is held in position or moved forward or backward along the shaft by a strong lever 102 with its fulcrum at 103. This lever is operated by turning the screw 104- by means of the hand lever 105. The mechanical pressure against cone 100 is applied by means of a thrust bearing (not shown) in block 106 and in operation this thrust is opposed by the thrust of the pulp being pushed against the cone by the rotating helical blade 107. The shaft 101 exerts an equal thrust against the thrust bearing 108.

In the dewatering of pulps of cellulose acetate and similar materials the thrust against the bearing 108 and against the cone 100 and its thrust bearing may rise to 56,400 lbs. The shaft 101 in a typical press is about 4 inches in diameter and about feet long. The helical blade is usually about 16 inches in diameter. The large thrust causes rapid wear on the thrust bearings with frequent shut downs for repair or replacement. Also the compressive force on the shaft sometimes causes this shaft to curve out of line and press the blade against the perforated housing 109 causing a flow of metal which closes the perforations and also frequently causing the shaft to break. This is especially likely to happen during a bearing failure.

The pulp fed to a press of this type often varies in water content and often in other respects as well. Its feed may sometimes be heavy and sometimes light so that it is necessary, if constant pressure is to be applied to the pulp, to vary the opening between the cone 100 and the end of housing 109 from time to time. If the load of pulp in the system is heavy and the opening between cone and housing is small, the pressure will become too great and damage to bearings and shaft are likely to occur. On

United States Patent 3,140,652 Patented July 14., 1964 'ice the other hand, if the opening between cone and housing 'is large with respect to the amount of pulp in the press,

then the pressure on the pulp is low and it will retain a large amount of water. Therefore, for efficient operation of a press it is necessary to change the clearance between cone and housing from time to time without stopping the press. In the press shown in FIGURE 1 this is done by turning the screw 104 by use of hand lever 105.

Another type of press is shown in FIGURE 2 with housing 209 and bearings (not shown). In this press also the cone 200 is keyed to the shaft 201 and rotates with the shaft, but is free to slide axially along the shaft. In this case the cone 200 is moved forward to backward along the shaft by the threaded nut 210 having radial spokes 211 mounted therein. In normal operation this nut 210 also rotates with the shaft 201 and remains at the same position on the shaft. However, since the shaft 201 rotates at a low speed of about 5 r.p.m., it is possible to turn the nut 210 by striking the spokes 211 with a sledge hammer, driving the nut 210 either forward or backward to decrease or increase the clearance between cone 200 and housing 209.

The press shown schematically in FIGURE 2 has some advantages over that shown in FIGURE 1. The greatest advantage is that practically no thrust is transmitted to the bearings. The thrust is borne by the shaft which is subjected to tension between the nut 210 supporting the cone 200 and the helical blade 207. Bearings in this press will last for long periods and since the shaft is subjected only to tension, there is less tendency for it to bend and damage the housing, or to break.

The disadvantage of this press is that it is inconvenient and somewhat hazardous to change the clearance between cone and helical blade or housing. The spokes must be struck while they are rotating and serious accidents have happened during this somewhat difficult procedure. Furthermore, the adjustment cannot be made quickly since the nut 210 can be turned only a fraction of a revolution with each hammer blow and the press may be damaged before a correction can be made. Because of the hazards and inconvenience of this type of press, the press of FIG- URE 1 replaced the press of FIGURE 2, but was still unsatisfactory as explained above. It was somewhat easier to adjust than the press of FIGURE 2 but the wear and tear on bearings, shaft and housing made its operation uneconomical. There was, therefore, a definite need for an improved dewatering device that would not have the deficiencies of either of these two prior art presses.

The object of the present invention is to provide an improved mechanism for quickly, safely, and accurately adjusting the clearance between a press cone and its housing in a helical blade press while the press is operating. A further object is to develop such a cone adjusting mechanism which will eliminate the tremendous thrust on the shaft bearings in a helical blade press. A still further object is the provision of such a cone adjusting mechanism which will automatically change the cone clearance in response to variations of current through an electrical drive motor.

Further objects and advantages will be apparent from a consideration of the following specification and claims in conjunction with the accompanying drawings in which:

FIGURE 1 is a schematic illustration of one form of prior art helical blade pulp dewatering press,

FIGUREZ is a schematic illustration of another form of prior art helical blade pulp dewatering press,

FIGURE 3 is a partial side elevational view partly in section of a liquid separating press embodying features of the present invention,

FIGURE 4 is an end view of the press of FIGURE 3 with certain parts broken away, and

FIGURE 5 is a block diagram schematic presentation of a system embodying features of this invention for automatically adjusting the cone position in accordance with the electrical load on the press unit electrical drive motor.

The above objects are accomplished in the present 1nvention by the apparatus depicted in FIGURE 3 which comprises a threaded nut 320 on a threaded portion 321 of the shaft 301 of a helical press, two ring gears 322 and 323 each having a brake band 324, a chuck type pair of gears 325 and 326 meshed respectively with the two ring gears 322, 323 and with the threaded nut 320; the struc* ture so arranged that when the brake band 324 on one ring gear 322 is tightened the nut 320 will be rotated in one direction with respect to the shaft 301, and when the brake band 324 on the other ring gear 323 is tightened, the nut 320 will rotate in the opposite direction with respect to the shaft 301, causing the press cone 300 to move in one direction or the other along the shaft.

The improvement in this press apparatus of FIGURES 3 and 4 primarily involves the mechanism for adjusting the cone 300 to vary the clearance between cone 300 and housing 309. The bearings are not shown in these figures of the drawing. In normal operation cone 300, block 330 and nut 320 all rotate with the shaft 301 at about 5 rpm. It will be noted that block 330 is keyed to the shaft, but free to slide along the shaft along with cone 300. Nut 320 is threaded and screwed onto the threaded portion 321 of the shaft 301. The ring gears 322 and 323, rotate freely and independently of block 330 and nut 320 respectively. Brake bands 324 do not rotate. The ring gears 322 and 323 are meshed with gear 325 which is rigidly connected with gear 326 which is meshed with the gears on nut 320, but is not in contact with block 330.

The end of shaft 301 is threaded with beveled threaded portion 321 which matches the threads in nut 320. These threads withstand the full thrust of the press.

In normal operation the helical blade 307 of the press, the cone 300, block 330, nut 320 and ring gears 322 and 323, all rotate together and gears 325 and 326 are rotationally still about their own axes, but revolve bodily around the shaft 301 with the other parts. The shaft 301 rotates in the direction such that the top of the shaft comes toward the viewer. Now if the brake band 324, on the right as viewed in FIGURE 3, is tightened on ring gear 323, the latter will be slowed down or stopped so that it will no longer rotate with the remainder of the assembly. This will cause gears 325 and 326 to rotate about their axes as they continue to revolve around the shaft. The rotation of gear 326 will drive nut 320 to the right as seen in FIGURE 3 so that it rotates faster than shaft 301 and the entire assembly, including cone 300 will move to the right along the shaft and will decrease the clearance between cone 300 and housing 309.

If the other, or left hand in FIGURE 3, is tightened on ring gear 322, then the reverse will happen. As ring gear 322 slows down or stops, gears 325 and 326 will be caused to move to the left in FIGURE 3 and gear 326 will cause nut 320 to rotate slower than shaft 301 and the entire assembly will move to the left increasing the clearance between cone 300 and housing 309. When the assembly moves to the right the nut 320 presses against the thrust washer 331 which contacts block 330 which in turn contacts cone 300. When the control assembly moves to the left, it pulls the cone 300 along with it by means of the pin 332 which is an extension of the axle of the gears 325 and 326. The pin 332 is firmly held in block 330 and the end of pin 332 slides in an annular groove in the nut 320.

The adjustment by means of brake bands 324 as described above may be slow or rapid depending on whether the ring gear involved is merely slowed down or stopped. Thus, the clearance between cone 300 and housing 309 can be varied quickly before trouble develops or before wet pulp is allowed to escape. Or the adjustment can be slow, if desired, but accurately controlled to give the correct desired pressure on the pulp. In one embodiment of this invention the electrical motor driving the shaft ordinarily requires or draws about 20 amperes of current which is continuously shown on an ammeter and registered on a time chart. Variations in the drive motor load as reflected in the reading of the ammeter will indicate a need for changing the clearance between cone and housing. A higher current will show that the pressure against the helical blade 307 is abnormally high calling for more power from the motor. The clearance should be increased to prevent damage to the equipment and possibly to the pulp being processed. If the current is low, the pulp is going through under too low a pressure and will carry too much water and impurities. Accordingly, decreasing the clearance would be desirable.

The operation of brake bands 324 can, if desired and with ordinary skills, be made entirely automatic by the use of solenoids activated by changes in the shaft drive motor current.

It will be obvious that in this press there will be no thrust upon the shaft bearings, hence bearing replacement is no longer a factor in maintenance cost. The shaft is now under only stretch tension, instead of the compression that occurs in the press of FIGURE 1. There is no tendency for the shaft to bend and damage the housing and shaft breakage has been substantially eliminated by apparatus embodying this invention.

The power savings achieved by the elimination of shaft deflection and heavy thrust loads on bearings is converted to useful work resulting in a pressed pulp with an average moisture content 5% lower than that of pulp processed through presses as shown in FIGURE 1. This means a corresponding reduction in the heat required to dry the pulp.

The improved press of this invention also operates more safely than either of the earlier presses.

As an illustrative indication of the advantages and utility of the present invention the following comparison was made.

The press shown in part in FIGURE 3 was used to extract water from a pulp containing 3% cellulose acetate. This press rotating at 5 rpm. continuously reduced the pulp to a product containing 60% cellulose acetate and 40% water. It was found that on the average 5% more water was removed from similar pulp than when operating with the press shown in FIGURE 1. Furthermore, over a period of several months, there was no bearing failure since with the improved apparatus bearing thrust was eliminated. Since no force was acting to deflect the shaft, there was no shaft breakage and no erosion of housing by the helical blades. With the old type of press the holes in the housing were frequently closed by such abrasion and had to be drilled out. In the new equipment a small part of the shaft is subjected to tension and none of it to compression. This is believed to contribute to the improved results. A significant reduction in operating accidents occurred with the press of this invention as compared with the frequent accidents occurring with the conventional press shown in FIGURE 2 where a sledge hammer is used to adjust the press cone.

Various types of automatic controls or actuating devices, as discussed herein, can be incorporated to obtain instantaneous response of the cone adjuster mechanism to changes in the current requirements of the electrical press drive motor.

While a preferred embodiment of this invention has been described in detail, many variations and modifications within the spirit of this invention will occur to those skilled in the art. All such variations and modifications are considered to fall within the scope of the following claims.

What is claimed is:

1. An improved press apparatus for extracting liquid from a compressible mass containing a liquid, said apparatus comprising in combination, a hollow foraminous cylindrical casing having a central axis, a rotating assembly mounted for rotation about the axis of said casing and positioned adjacent one end of said casing, said assembly comprising a first rotating element positioned within said casing and having a material forwarding surface, said element and said material forwarding surface constructed and arranged to positively displace a mass of material positioned within the casing in a given axial direction toward said one end of the casing, said assembly, further comprising a second element mounted for rotation with said assembly positioned adjacent said one end of said casing, said second element constructed and arranged to oppose movement of material displaced toward said end of said casing to compress the same during rotation of said assembly, said second element cooperating with said one end of the casing to form a restricted discharge passageway for exit of the compressed material during rotation of said assembly, said second element mounted for limited axial movement along the casing axis with respect to the casing during rotation of said assembly, said assembly further comprising a planetary gear means directly physically engaged with said second element, and braking means cooperating with said planetary gear means, said braking means actuatable for positively rapidly smoothly selectively adjusting the axial position of said second element with respect to said one end of said casing in an infinitely variable and reversible manner during rotation of said assembly to thus vary the size of the restricted discharge passageway.

2. The improved apparatus of claim 1 in which said assembly further comprises a cam means for causing axial movement of said second element and said planetary gear means comprises a third element rotatably mounted on said assembly, said third element positioned in opera tive engagement with said cam means of said assembly such that rotation of said third element relative to said assembly causes axial movement of said third element relative to said assembly, said third element operatively coupled to said second element to transmit bidirectional axial movement thereto, a first annular bevel gear member freely rotatably mounted on said second element for rotation about an axis coincident with said casing axis, a second opposed annular bevel gear member freely rotatably mounted on said third element for rotation about an axis coincident with said other bevel gear axis, a third annular bevel gear member rigidly connected to said third element and in axial alignment with said other gear members, at least one planetary bevel spur gear member operatively engaged with said first and second bevel gear members for rotation about its own axis perpendicular to the axis of the other bevel gear members and supported in said second element for rotation, therewith and for revolution about the axis of said other bevel gear members, said planetary bevel spur gear provided with another aligned planetary bevel spur gear rigidly attached thereto and in operative engagement with said third annular bevel gear member, said braking means cooperating with said annular bevel gear members for selectively causing relative rotation between said first bevel gear member and the second element and between the second bevel gear and the third element to vary the position of the third and second element axially with respect to the casing.

References Cited in the file of this patent UNITED STATES PATENTS 2,178,714 Anderson Nov. 7, 1939 2,340,009 Meakin Jan. 25, 1944 2,609,744 Rietz Sept. 9, 1952 2,901,967 Ornulf Dahl Sept. 1, 1959 FOREIGN PATENTS 1,227,735 France Mar. 7, 196

Claims (1)

1. AN IMPROVED PRESS APPARATUS FOR EXTRACTING LIQUID FROM A COMPRESSIBLE MASS CONTAINING A LIQUID, SAID APPARATUS COMPRISING IN COMBINATION, A HOLLOW FORAMINOUS CYLINDRICAL CASING HAVING A CENTRAL AXIS, A ROTATING ASSEMBLY MOUNTED FOR ROTATION ABOUT THE AXIS OF SAID CASING AND POSITIONED ADJACENT ONE END OF SAID CASING, SAID ASSEMBLY COMPRISING A FIRST ROTATING ELEMENT POSITIONED WITHIN SAID CASING AND HAVING A MATERIAL FORWARDING SURFACE, SAID ELEMENT AND SAID MATERIAL FORWARDING SURFACE CONSTRUCTED AND ARRANGED TO POSITIVELY DISPLACE A MASS OF MATERIAL POSITIONED WITHIN THE CASING IN A GIVEN AXIAL DIRECTION TOWARD SAID ONE END OF THE CASING, SAID ASSEMBLY, FURTHER COMPRISING A SECOND ELEMENT MOUNTED FOR ROTATION WITH SAID ASSEMBLY POSITIONED ADJACENT SAID ONE END OF SAID CASING, SAID SECOND ELEMENT CONSTRUCTED AND ARRANGED TO OPPOSE MOVEMENT OF MATERIAL DISPLACED TOWARD SAID END OF SAID CASING TO COMPRESS THE SAME DURING ROTATION OF SAID ASSEMBLY, SAID SECOND ELEMENT COOPERATING WITH SAID ONE END OF THE CASING TO FORM A RESTRICTED DISCHARGE PASSAGEWAY FOR EXIT OF THE COMPRESSED MATERIAL DURING ROTATION OF SAID ASSEMBLY, SAID SECOND ELEMENT MOUNTED FOR LIMITED AXIAL MOVEMENT ALONG THE CASING AXIS WITH RESPECT TO THE CASING DURING ROTATION OF SAID ASSEMBLY, SAID ASSEMBLY FURTHER COMPRISING A PLANETARY GEAR MEANS DIRECTLY PHYSICALLY ENGAGED WITH SAID SECOND ELEMENT, AND BRAKING MEANS COOPERATING WITH SAID PLANETARY GEAR MEANS, SAID BRAKING MEANS ACTUATABLE FOR POSITIVELY RAPIDLY SMOOTHLY SELECTIVELY ADJUSTING THE AXIAL POSITION OF SAID SECOND ELEMENT WITH RESPECT TO SAID ONE END OF SAID CASING IN AN INFINITELY VARIABLE AND REVERSIBLE MANNER DURING ROTATION OF SAID ASSEMBLY TO THUS VARY THE SIZE OF THE RESTRICTED DISCHARGE PASSAGEWAY.

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