Patent Publication Number: US-3880711-A

Title: Vacuum cylinder assembly having angled, tear-shaped, sieve supporting foils

Description:
United States Patent 1 Hayes, Jr.  
 [451 Apr. 29, 1975 VACUUM CYLINDER ASSEMBLY HAVING ANGLED. TEAR-SI-IAPED, SIEVE SUPPORTING FOILS [76] Inventor: Millard F. Hayes, Jr., PO. Box 294,  
 Warrensburg, NY. 12885 [22] Filed: Sept. 12, I973 [2]] Appl. No.: 396,868  
 [521 U.S. Cl. 162/357; 162/352; 162/372 [51] Int. Cl D2 1/60; D2lf 3/10 [58] Field of Search l62/357. 317, 368, 369. 162/372, 352, 374  
 [56] References Cited UNITED STATES PATENTS 1988.402 l/l935 Thomas 162/357 3,272,692 9/1966 Hayes et al. 162/357 X Primary E.\&#39;umI&#39;m&#39;rS. Leon Bashore Aszrislan! E.\&#39;amincr-Richard V. Fisher Attorney, Agent, or Firm-Ross, Ross &amp; Flavin [57] ABSTRACT A vacuum cylinder assembly includes a continuous outer subassembly including a circular sieve supported on a plurality of spaced circumferentially-arranged ring-mounted supporting foils, a stationary inner subassembly concentrically sleeved within the outer sub assembly and including a hollow cylinder having an arcuate through slot extending transversely through substantially the entire width of the outer subassembly and peripherally through a substantially 90 angle, an outwardly projecting walled passageway fixed to the cylinder circumadjacent the slot and extending as a mouth from the cylinder periphery to adjacent the foils of the outer subassembly, wall elements for dividing the passageway in gridlike manner into a plurality of sub-passageways, the outer subassembly being ro tatably driven relative to the inner subassembly for the confrontation of an ever-changing portion of the peripheral area of the sieve with the mouth of the passageway, and a suction device within the hollow of the cylinder for exerting an extracting effort upon the sieve, the subassemblies being cooperantly disposed to draw effluent through the sieve into the hollow of the cylinder via the passageway. The supporting foils are each generally tear-shaped in cross-section having a leading side, in the direction of roll rotation, which is angled slightly inwardly so as to generate an inward pumping action, and having a top trailing angle with a downwardly sloping configuration serving to cause a slight vacuum for contributing to higher drainage.  
 3 Claims, 4 Drawing Figures VACUUM CYLINDER ASSEMBLY HAVING ANGLED, TEAR-SHAPED, SIEVE SUPPORTTNG FOILS This invention relates to a vacuum cylinder assembly for apparatus used in papermaking and more particularly to the cylinder construction and function.  
  The invention is used as a cylinder mold upon the periphery of which a web is formed. Conventionally, such a mold includes a cylindrical wire mesh or cloth or face supported by a pair of spaced end spiders and a plurality of intermediate spiders therebetween, which spiders mount arcuately-spaced supporting rods, there being a winding wire continuously wound upon the supporting rods to form a support for the face. The face may either be of a single layer of wire mesh or a pair of layers of differing mesh, the outermost being of fine mesh and the innermost being ofa more coarse mesh. Operationally, stock, in the form of fibers entrained in water, is delivered from exteriorly of the mold or roll at a speed generally corresponding to the mold peripheral speed and onto the face. The majority of the fibers are held upon the face and define the web which subsequently becomes the paper sheet.  
  Alternatively, cylinder molds have sometimes employed a perforated solid casting with a cooperant mesh face comprising the roll peripheral surface, all so that the need for supporting spiders and winding rods is eliminated. Suction boxes are conventionally employed within the casting to supply the vacuum to the inner surface of that quadrant approaching a coacting couch roll. Or suction may be applied to one quadrant (which may be under water or covered by the forming web) while another adjacent sealed off quadrant may be exposed to air. But these mold types all suffer the general disadvantage that the mold is submerged in part in a slurry of the fiber-carrying water and hence is subject to turbulence so as to interfere disastrously with web formation, and the further disadvantage stemming from increased damaging effects of the centrifugal force resultant from the size of the charges of effluent spouting through the casting perforations, which charges involve forces considerably higher than any involved with the usually small droplets passing through the conventional wire cloth. The solid shell provides what can only be defined as a hard deck beneath thg face or clothing. This invention distinguishes therefrom by providing a soft deck.  
  The disadvantages of immersion and generated centrifugal forces were offset in part by the application of suction internally of the face so as thereby to build up mold wherein the stock is delivered to a quadrant of the cylinder through an adjacently-disposed channel or -throat, which channel or throat is of a graduallydecreasing size to give the accelerating effect and incorporates appropriate sealing means for restricting the face area. The speed of stock flow, as it approaches the face, is accelerated so that its velocity is approximately the same as the cylinder peripheral speed when the stock is spouted. To achieve this, the stock is directed substantially tangentially of the roll via the channel or throat.  
  Further illustratively, the invention is applicable for use in such as suction rolls employed at various points in papermaking apparatus. As an example, it may be employed as a suction couch or breast roll, by means of which the formed web may be transferred, following passage along the forming wire, to the felt, whereat the supplied suction further removes water from the web and further pulls the fibers together so that web transfer can be effected at high speed.  
  Conceivably, the cylinder hereof can be trunnion mounted, with a topmost-arranged headbox and supporting end seals and catch pan and vacuum breaker beneath the couch or pick up area.  
  The invention avoids the prior art disadvantages attendant to the drawing of a vacuum on a roll. It does it with the mesh face design cooperant with a vacuum upon a portion of the face circumference via a plurality of so-called air/water sheds in communication with a hollow central core.  
  The air/water sheds and central core are each stationary and a pair of spaced opposite circumferential end rings and a plurality of axially-spaced intermediate rings therebetween define means upon which a plurality of transversely-extending foils may be mounted, on the outer notched edges of which foils a winding wire is wound and upon which winding wire a wire mesh face is mounted, with the rings, foils, winding wire and face being rotatable unisonly as an outer subassembly relative to the central core and its dividing walls and water sheds or vanes which cooperantly define the water collectors and which function as the inner subassembly.  
  The two subassemblies, one rotatable relative to the other, serve to delineate a squirrel cage construction with the wire mesh of the face being wound upon what is defined as an open or soft deck rather than being wound upon a perforated shell, there being considerable spacing between the face or cloth and the area where the excess effluent is captured. The tendency to take water upwardly to the forming area is negated as the central core is non-rotatable and effluent captured therewithin is curbed of any tendency it might exhibit of trying to move outwardly through the cloth.  
  The stationary central core is provided with an elongated arcuate slot extending from its outer peripheral surface through to its interior chamber throughout most of the side-to-side roll width and through an angle slightly in excess of to define a so-called open core quadrant which is stationarily disposed relative to the upper ascending quadrant of the assembly when operational.  
  The total area of the core slot is divided into a plurality of smaller areas by means of a series of spaced obliquely-disposed dividing walls extending transversely of the core coextensive with and slightly in excess of the transverse width of the core slot so as thereby to be secured to the respective of oppositelydisposed dividing wall rings fixed upon and extending radially outwardly of the core adjacent the opposite sides of the slot.  
  The total area of the core slot, so divided into smaller areas each disposed in an axis transversely of the assembly, is further subdivided into a plurality of water collecting areas as defined by the spaces between adjacent pairs of circumferential intermediate rings of the outer rotatable subassembly, which rings rotate past the core slot, and adjacent pairs of corresponding arcuate water sheds or vanes straddling the core slot, there being one such water shed or vane disposed radially inwardly of each circumferential intermediate ring.  
  The transverse dividing walls and the arcuate sections of water sheds cooperate with the adjacent portions of the intermediate rings as they move through the quadrant represented by the core slot to define a plurality of closely adjacent air/water collectors through which air and effluent may pass from roll periphery to core interior.  
 In the drawings:  
  FIG. 1 is a fragmentary view in cross section of the cylinder construction;  
 FIG. 2 is a view in section along line 2-2 of FIG. 1;  
  FIG. 3 is an enlarged view in section along line 3.3 of FIG. 2; and  
  FlG.4 is an enlarged view in section along line 44 of FIG. 1.  
  The cylinder assembly includes an outermost face or cloth in the form of a mesh of small diameter closely spaced wires defining openings through which the effluent can pass, such face being normally of between 50 and 80 mesh (wires per inch) to form a porous cylindrical covering for the cylinder or roll for the support of a mat of paper fibers as laid down thereupon and travelling in the direction of roll rotation. The mesh is supported, directly or with an intermediate coarser mesh, by a winding wire 12 wrapped circumferentially around the cylinder and upon a plurality of spaced, transversely disposed supporting foils 14 which are in turn supported by a pair of spaced end rings 16 and 16, with the supporting foils having opposite ends each fixed to the adjacent end ring 16 and being additionally fixed to each of a plurality of axially-spaced intermediate rings 18.  
  The end rings are each suitably bolted as at 20 to an adjacently-disposed annular end head 22.  
  In the case of conventional cylinders, the apparatus additionally will include a shaft upon which spiders are mounted, which shaft is rotated with the spiders and the face.  
  contrariwise, in this invention, rather than rotating the shaft with the rings and face, the rings are themselves rotatably mounted upon a central stationary hollow cylindrical core 30.  
  At each end of core 30, one of the end heads 22 is sleeved thereover, each such end head having a right angular radially-disposed upstanding portion 32 confronting and suitably bolted to the outboard face of the adjacent end ring and being further supported relative to the core or its extensions as by a plurality of bearings 33 circumferentially-arranged about the end head outer periphery and suitably seated relative thereto by means of an outer annular enclosing collar 34 unitary with a cylinder support stand 36.  
  The wall of core is provided with an enlongated arcuate through slot extending throughout most of the side-to-side cylinder width and through an angle slightly in excess of 90 to define a so-called open core quadrant which is stationarily disposed relative to the upper ascending quadrant of the assembly.  
  Overlying the core slot and extending between the end walls thereof are a plurality of spaced arcuate triangular-shaped water sheds or vanes 60, there being one such water shed disposed radially inwardly so as to be aligned with a respective intermediate ring 18 radially outwardly thereof, the angular disposition of the walls of the water sheds providing roofs along which the effluent water passing into the cylinder through the face and between the foils and rings is deflected.  
  The total area covered by core slot 40 will be seen to be divided into three equi-spaced smaller areas of identical dimensions by a series of spaced obliquelydisposed dividing walls 42, 44, 46 and 48 which extend transversely of and somewhat co-extensive with the core slot, they each being rigidly fixed at their respective ends to an adjacent circumferentially arranged dividing wall ring secured to and extending radially outwardly of the core immediately adjacent a respective side of core slot 40.  
  The dividing walls each extend outwardly toward but are slightly spaced from the circumferential arrangement of supporting foils l4 and each such wall is provided at its outboard end with a flattened wiper 52 suitably secured thereto as by bolting 54. The outermost portion of each wiper is suitably notched as at 56 for accommodating the through passage of the respective intermediate ring as the outer assembly is rotated relative to the inner assembly.  
  It will be noted that supporting foils 14 are each generally tear shaped in cross section with its leading side, in the direction of rotation b, being angled slightly inwardly so as to generate an inward pumping action, and with the top trailing angle having a downwardly sloping configuration serving to cause a slight vacuum which contributes to higher drainage.  
  The advantage of this supporting foil over the typical round rods of prior art structures, they being usually /ainches in diameter, is that, as the cylinder rotates at high peripheral speed, any white water moving past or through the wire cloth likely falls on the rods. When the water hits the leading side of the round rod, above its horizontal centerline, the forces due to velocity tend to throw the water tangentially or even upwardly. Contrariwise, with the foil hereof, the objectionable surface has been reduced by minimizing it to something in the order of a l/l6inches radius. Too, the straight sided leading surface has been angled in such manner as to create the inward bumping action, much as a silent vane fan. Additionally, the top back surface is shaped as a foil so as to create a vacuum which allows the water to drop backwardly and downwardly without resistance.  
  The arcuate portion or quadrant of the roll periphery delineated by and between dividing walls 42 and 48 is thus divided into three parts. The first part is that to which the stock is directly applied via the channel or throat and in which initial drainage ensues; the second part is the portion directly in advance of the stock entrance segment and in which secondary drainage ensues; and the third part is a portion in advance of the second segment and which is exposed only to air.  
  Substantially the entire axial extent of the face is served by the openings defined by the air/water sheds.  
  The cylinder machine may function with a vat, not shown, within which the cylinder will be rotatably mounted, and to which the stock will be supplied for formation of the web on face 10, with the opposite ends of the cylinder being sealed against leakage with respect to the vat as by a retaining cover enclosing a seal between each end spider and core.  
  The end portions of core 30 may each be connected to a connector having discharge openings connected to appropriate piping. One set of openings may be each connected to the suction side of an air pump or fan capable of supplying enough of a negative pressure by pumping air therefrom that an added head in the order of, say l0 or inches of water may be provided across the face thereby adding to an hydraulic head of say 6 to 7 inches of water as normally employed in a cylinder mold machine, to encourage both water and air to pass through the cylinder face and into the air/water sheds. The air and water then pass into the central chamber of the core and is then directed outwardly into an ap propriate white water collector by suitable discharge means. The air of course will flow to the suction side of the pump through its provided openings.  
  Additional concentrated stock may be added to the white water discharged into the white water collector so that the combination of white water discharge and added stock will bring the discharge of the collector back to a proper stock consistency for vat resupply.  
  A pump may be provided to supply the appropriate hydraulic head to force the stock into the throat adjacent the cylinder.  
  As is conventional, the formed web may be transferred to a felt which contacts and drives a couch roll of conventional design. Since the felt is in contact with the cylinder, the cylinder is driven in the same direction as the felt to cause web transfer from face to felt.  
  These components are not further shown or described because they are of conventional and well known form and purpose. It will be evident, however, that the stock is delivered to a portion of the periphery of the face which is of less circumferential extent than the distance between the water collector wall portions. As a result, only moisture from the formed web and air is drawn through the face from the portion of that web. This tends to consolidate the fibers, as well as to reduce the moisture content, so that the web may more easily be transferred at high speed to the felt.  
  Though the cylinder may be driven by the felt and couch roll, it will be evident that the cylinder could be directly driven, as for instance by providing it with a flange upon which a gear could be mounted, that gear being driven through conventional motive means.  
 I claim:  
  1. In a vacuum cylinder assembly, the combination of: a continuous outer subassembly including a circular sieve supported on a plurality of spaced circumferentially-arranged ring-mounted supporting foils,  
 a stationary inner subassembly concentrically sleeved within the outer subassembly and including a hollow cylinder having an arcuate through slot extending transversely through substantially the entire width of the outer subassembly and peripherally through a substantially 90 angle,  
 an outwardly projecting walled passageway fixed to the cylinder circumadjacent the slot and extending as a mouth from the cylinder periphery to adjacent the foils of the outer subassembly, the outer subassembly being rotatable relative to the inner subassembly for the confrontation of an ever-changing portion of the peripheral area of the sieve with the mouth of the passageway, and  
 the subassemblies being cooperantly disposed to draw effluent through the sieve into the hollow of the cylinder via the passageway, the supporting foils each being generally tear shaped in cross section having a leading side, in the direction of roll rotation which is angled slightly inwardly so as to generate an inward pumping action, and having a top trailing angle with a downwardly sloping configuration serving to cause a slight vacuum for contributing to higher drainage.  
  2. Apparatus including a suction roll, for use in paper manufacture, and comprising: a stationary hollow core. a pair of end rings and a plurality of axially spaced intermediate ringsmounted circumferentially about the core.  
 a plurality of transversely arranged spaced supporting foils carried by the rings,  
 a winding wire wound about the supporting foils,  
 a wire mesh face mounted upon the winding wire,  
 the rings and supporting foils and winding wire and wire mesh face defining a subassembly rotatable relative to the core, a pair of end heads disposed adjacent the opposite ends of the rotatable subassembly and mounting the respective adjacent end ring of the pair,  
 bearing means for the journalling of the end heads relative to the core,  
 thecore having an elongated slot extending through the core wall between the end heads in a side-toside direction, through a substantially angle in an end-to-end direction, a plurality of spaced dividing walls extending outwardly from and transversely of the core slot,  
 a plurality of spaced arcuate water sheds disposed over the core slot in directions at right angles to the dividing walls for defining cooperantly with the dividing walls, a plurality of air and water collectors each extending from adjacent the inner surface of the face to a respective portion of the core slot leading into the hollow of the core, the supporting foils each being generally tear shaped in cross section having a leading side, in the direction of roll rotation which is angled slightly inwardly so as to generate an inward pumping action, and having a top trailing angle with a downwardly sloping configuration serving to cause a slight vacuum for contributing to higher drainage.  
 3. Apparatus including a suction roll, for use in paper manufacture, and which comprises:  
 an elongated stationary core having a central chamber and forming an axis for the roll,  
 a pair of end rings and a plurality of axially spaced intermediate rings mounted circumferentially about the core,  
 a plurality of transversely arranged spaced supporting foils carried by the rings,  
 a winding wire wound about the supporting foils,  
 a wire mesh face mounted upon the winding wire,  
 the rings and supporting foils and winding wire and wire mesh face defining a rotatable subassembly being rotatable relative to the core,  
 a pair of end heads disposed adjacent the opposite ends of the rotatable subassembly and mounting the respective adjacent end ring of the pair,  
 bearing means for the journalling of the end heads relative to the core,  
 the core having an elongated slot extending through the core wall between the end heads in a side-toside direction and through a substantially 90 angle in an end-to-end direction into the core interior.  
 a plurality of spaced dividing walls extending outcore central chamber, the supporting foils each wardly from and transversely of the core slot. being generally tear shaped in cross section having a plurality of spaced arcuate water sheds disposed a leading side, in the direction of roll rotation over the core slot in directions at right angles to the &#39;which is angled slightly inwardly so as to generate dividing walls for defining cooperantly with the dian inward pumping action, and having a top trailing viding walls, angle with a downwardly sloping configuration a plurality of air and water collectors each extending serving to cause a slight vacuum for contributing to from adjacent the inner surface of the face to a rehigher drainage.  
 spective portion of the core slot leading into the