Abstract:
Bowed spreader apparatus for laterally stretching, or stressing, a web of material carried in a selected direction along a conveyor path includes an elongate stationary spreader bar extending laterally of the path. The spreader bar has a web support face which is convexly curved both about the longitudinal axis of the bar and along the longitudinal axis. The bar includes a formed elongate support body having a degree of flexibility allowing the body to be bent in a bowed configuration. A face surface of the body is formed in a convex curve about the longitudinal axis of the body and a plurality of hardened elements are individually secured to and cover the face surface of the support body. An underlying interchangeable profiling support having a convexly curved upper surface forms the spreader bar into a selected bowed configuration.

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates generally to apparatus for laterally stressing, or stretching, a web of material carried in a selected direction along a conveyor path. More specifically, it relates to a stationary bowed spreader bar over which the web of material is carried. 
     SUMMARY OF THE INVENTION 
     In the manufacturing of paper and other flexible sheet materials, a web of such material may be carried in a selected direction along a conveyor path and is guided along such path by rollers. The material may be carried on a conveyor belt which may be made of metal wire, woven plastic, or other web carrying materials. 
     As the conveyor and web are carried through the process it may be necessary or desirable to provide a lateral stressing, or stretching, of the material either to remove wrinkles or other deviations, or to align the materials within the conveyor. 
     In the past various spreader rolls, or bowed rolls, have been used. These prior rolls have an outwardly bowed, or curved shape, and rotate about a fixed axle. Various operational problems occur with such devices, such as lubrication and flexural failures. 
     A general object of the present invention is to provide apparatus including a substantially stationary bowed spreader over which a web of material may be carried along a selected direction in a conveyor path, with the apparatus laterally stressing, or stretching, the web and overcoming many of the problems that have occurred in prior roller devices. 
     Another object of the present invention is to provide spreader apparatus which includes an elongate stationary spreader bar supported adjacent and extending substantially laterally of the conveyor path, the bar having a web support face which is convexly curved both about the longitudinal axis of the bar and along the longitudinal axis of the bar such that a web of a material carried thereover under tension is urged to spread, or stretch, laterally. 
     A further object of the invention is to provide such apparatus in which the spreader bar comprises a formed elongate support body having a degree of flexibility allowing the body to be bent into a bowed curve along its longitudinal axis and a plurality of hardened elements individually secured to and covering the face surface of the support body to form a web carrying face for the spreader bar. 
     A still further object of the invention is to provide such apparatus with a profiling support interposed between the base and support body to bend the support body into a desired bowed configuration. More specifically, the profiling support has a side which engages the carrier bar and is configured to bend the bar into a desired bowed configuration. Interchangeable profiling supports may be used to provide different bowed configurations for the bar. 
     Yet another object is to provide such apparatus in which the hardened elements are disposed in multiple rows and columns extending across the face surface of the support body with the hardened elements being secured at their rear faces to the support body and with front faces thereof forming the web carrying surface. Edge margins of an element are contiguous but unjoined to edge margins of adjacent elements, to permit bending of the carrier bar to varying bowed configurations. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other objects and advantages of the present invention will be apparent from the following detailed description of a preferred embodiment and from the attached drawings wherein: 
     FIG. 1 is a top plan view of spreader apparatus according to an embodiment of the invention; 
     FIG. 2 is an enlarged side elevation view taken generally along the line  2 — 2  in FIG. 1; 
     FIG. 3 is an enlarged top plan view of the left end portion of the spreader apparatus shown in FIG. 1; and 
     FIG. 4 is an enlarged cross sectional view taken generally along the lines  4 — 4  in FIG.  3 . 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENT 
     Referring first to FIGS. 1 and 2, apparatus according to the present invention is indicated generally at  10 . It includes a bowed spreader bar, or spreader bar assembly,  12 , disposed in a conveyor line between a pair of upstream and downstream rollers  14 ,  16 . Shown generally in dashed outline is a conveyor belt, wire, or fabric  20 , used in papermaking to carry a web of material under each of rollers  14 ,  16  and across the upper web-carrying face  12   a  of spreader bar  12 . Rollers  14 ,  16  rotate clockwise as illustrated in FIG.  2  and the web, belt, wire, or fabric,  20  is carried along a conveyor path in the direction of arrows  22 . As illustrated in FIG. 1, the web or conveyor belt  20  has a width W 1  as measured laterally of the direction of the path along which it travels. 
     A pair of support columns  26 ,  28  are disposed laterally to opposite sides of the path for conveyor  20 . Spreader bar assembly  12  is disposed between and supported on support columns  26 ,  28  as will be described below. 
     In the illustrated embodiment of the invention, an elongate substantially rigid tubular cylinder  30  having circular end plates  32 ,  34  secured thereon extends laterally of the conveyor path between support columns  26 ,  28 . A pair of pivot shafts  36 ,  38  are secured to end plates  32 ,  34 , respectively, and extend outwardly therefrom as illustrated in FIG.  1 . Pivot shafts  36 ,  38  are received in clamp couplings  40 ,  42 . Each of the clamp couplings surrounds the periphery of its associated pivot shaft and has securing bolts associated therewith. When the bolts are loosened the pivot shafts and cylinder  30  coupled thereto may be rotated about pivot axis  44 . 
     As seen in FIGS. 2 and 4, at least a portion of a quadrant of cylinder  30  has been removed and an elongate, somewhat L-shaped, support base  50  has been secured thereto, as by welding. The support base includes an elongate base bar  52  and an elongate backing bar  54 . These extend substantially the full length of cylinder  30  and provide a substantially rigid support base for the spreader bar  12 . 
     Resting against both of base bar  52  and backing bar  54  is an elongate profiling support  56 . The profiling support is a substantially rigid member which extends substantially the full length of cylinder  30  and has a planar underside, or inner side,  56   a  which rests flush against base bar  52 . The upper, or outer, face, or surface,  56   b  of the profiling support is formed in a curved, or bowed, configuration. This upper, or outer, face is formed in a convex curve extending from its opposite ends toward its center, with the least elevation, or distance, from base bar  52  being at opposite ends of the base bar and its greatest upper surface elevation, or distance, being at the center. The profiling support  56  is secured to base bar  52 , as by the use of bolts  58 . 
     The spreader bar  12  comprises a formed elongate support body  62  having the cross sectional configuration illustrated generally in the cross hatched portion of FIG.  4 . As is seen, it has a substantially flat back side  62   a  which rests against backing bar  54 , a substantially flat bottom surface  62   b  which rests against the upper face  56   b  of profiling support  56 , and a convexly curved outer face surface  62   c . Face surface  62   c  is formed in a convex curve which extends about the longitudinal axis of support body  62 . Further, a plurality of elongate grooves  66  extending longitudinally of body  62  are formed in outer surface  62   c.    
     Body  62  is formed of a plastic material, which may be a fiber reinforced plastic material, which is capable of being flexed into a bow shaped configuration. Explaining further, the support body  62  initially is formed as a substantially straight element with no bowing along its longitudinal axis. The support body has a length L 1  corresponding substantially to the length of cylinder  30 , such that it fits within the space between end plates  32 ,  34  and extends transversely of the conveyor path. The support body also has a width W 2  measured in the direction of path  22 . 
     A plurality of hardened elements  70  are secured to the outer face surface of support body  62  to form a web carrying face for the spreader bar. The hardened elements  70  are ceramic tiles which, when viewed as in FIG. 3, have a substantially rectangular configuration. The tiles each have a front face  70   a  which, when assembled as illustrated, face outwardly to form a web carrying face surface for the spreader bar. Each tile has a rear face  70   b  opposite the front face which comprises a tongue portion which extends from the rear face and is received in a groove  66  in the face surface of support body  62 . An adhesive in groove  66  bonds these rear surfaces of the tiles and their tongue portion  70   b  to support body  62 . Each tile also has surrounding edge margins  70   c  extending between their front and rear faces and defining the substantially rectangular configuration for the illustrated tiles. 
     The tiles are individually secured to the outer face  62   c  of support body  62  in such a manner that they substantially cover the convex outer face of the support body. The edge margins of the individual tile elements are contiguous but unjoined to edge margins of adjacent tiles on the face. As is best seen in FIG. 3, the tiles are secured to the outer face of support body  62  in multiple rows and columns. In the embodiment illustrated, each column holds 8 tiles, and each row holds on the order of 35 tiles. The number of tiles shown in each column and row is merely exemplary. It has been found that the apparatus works well when the support body has a length L 1  which is at least as great and maybe slightly greater than width W 1  for the conveyor to be carried thereover, and each tile element has a first side-to-side dimension, or length, L 2  in the direction of the length of the support body which is less than 10% of the length L 1  of the support body. The side-to-side dimension, or width, W 3  of a tile  70  as measured in the direction of the width of the support body, in the illustrated embodiment, is between 10-25% of width W 2  of the support body. However width W 2  may be less than or greater than this range. The primary purpose of having multiple individually secured tile elements, each of which is only a minor portion of the length of the support body, is to permit bowing of the support body, while maintaining substantial covering by the tile elements over the web carrying face of the spreader bar. 
     The support body is secured to base  50  and profiling bar  56  as best illustrated in FIGS. 3 and 4. Support body  62  has notches  74  formed at its opposite ends as best illustrated in FIG.  4 . An angle bar  76  is engaged in notch  74  and is secured to support base  50  by bolts  78 . In this way, opposite end portions of support body  62  are held in place relative to base  50 . 
     As previously mentioned, upper surface  56   b  of profiling support  56  has been machined into a convexly curved configuration conforming to the bowed configuration which it is desired that spreader bar  12  assume in the apparatus. Profiling support  56  is interposed between bottom surface  62   b  of support body  62  and base bar  52 , such that it is in contact with bottom surface  62   b  of support body  62  throughout substantially the length of the spreader bar. Due to the flexibility of support body  62 , it is forced into a bowed configuration along its longitudinal axis as best illustrated in FIGS. 1 and 3. Since the multiple tiles  70  are not joined to each other along their contiguous edge margins they permit such bending of support body  62 . The spreader bar thus has an outer surface extending substantially across the width of the traveling web which has an outer face surface formed in a convex curve which is curved about the longitudinal axis of the spreader bar and a convex bowed configuration which is curved along the longitudinal axis over which the conveyor web may extend. The spreader bar is bowed generally in the direction of movement  22  of the material to be conveyed thereover. 
     As is best seen in FIGS. 3 and 4, a plurality of elongate clamp members  82  secure body  62  to profiling support  56  and to base  50  through bolts  84 . As seen in FIG. 4, support body  62  has a somewhat dovetail shaped portion  62   d  engaged by clamp  82  to draw the bottom  62   b  tightly against the top surface of profiling support  56 . 
     It should be understood that multiple profiling supports machined to different curved configurations may be interchanged with the profiling support  56  illustrated to produce a different bowed configuration for spreader bar  12 . With the bolt and clamp structure described it is a simple matter to remove the support body  62 , and one profiling support  56 , substitute a second profiling support of a different curved configuration, and then replace the support body. A second profiling support of slightly different curvature is indicated schematically by dashed line  56   c  in FIG.  3 . 
     The spreader bar  12  is illustrated in a first position in FIGS. 2 and 4. As previously noted, clamps  40 ,  42  may be released and the spreader bar apparatus rotated about pivot axis  44  (within an arc indicated generally at  88  in FIG. 2) to vary the orientation of the bar relative to the path of a web to be carried thereover. 
     As seen in FIGS. 1 and 2 an elongate sprayer tube  96  is secured to cylinder  30  and has a plurality of nozzles  98  arrayed at spaced intervals therealong. Water, or other liquid as desired, may be fed under pressure into the tube  96  and sprayed outwardly through nozzles  98  onto the under side of web  20  prior to the web engaging spreader bar  12 . 
     As a web of material is carried along path  22  it moves over the spreader bar under tension. As it moves over the spreader bar the bowed configuration of the bar extending generally in the direction of the path of travel of the conveyor web causes the conveyor and a web of material carried thereon to be stressed, or stretched, laterally in the directions of arrows  94   a ,  94   b , prior to engaging roll  16 . 
     While a preferred embodiment of the invention has been described herein, it should be apparent to those skilled in the art that variations and modifications are possible without departing from the spirit of the invention.