Patent Publication Number: US-3875682-A

Title: Sheet stabilizer for dryer

Description:
United States Patent Justus et al. Apr. 8, 1975 [54] SHEET STABILIZER FOR DRYER 3.4l 1.684 I l/l968 Tison et al. 226/l95 3.5 )7 70 4 2 [75] Inventors: Edgar .l. Justus; Elmer E. Crist, o9 5H9 Hemmer 3 ll 0 both of Below WIS. Primary Examiner-Kenneth W. Sprague gn z Beloil rpora n. m Assismnt Examiner-James C. Yeung Almrnev A em or Firm-Hill Gross Sim son Van 22 Fld: M .16.!973 P 1 ar Santen. Steadman. Chiara &amp; Simpson [2|] Appl. No.: 341,963  
  [57] ABSTRACT 7 [52] U.S. Cl. 34/118, 34/l20, 2-6/195 A dryer for evaporating mositure from a traveling [5 [1 Int. Cl. F26b 11/02 [58] Field of Search 34/1 104 paper web havmg dryer drums arranged in upper and &#34;f lower tiers with the web traveling in a serpentine path 226/195 242/752 26/63 68 up and down over the drums and edge rolls positioned [56} Reterences Cited at each edge of the web agalns t the uprunning span thereof dr1ven at a speed approxlmately 75 per cent of UNITED STATES PATENTS the speed of web travel and slightly deflecting the l.0l7 349 2/19l2 Tracy 34/118 web, preventing flutter of the edges at the higher web 1.170.309 2/1916 Meyers 34/[18 speeds. 2,067755 l/l937 Dyer, Jr 34/48 2.348.!62 5/l944 Warner 26/65 9 Claims, 2 Drawing Figures SHEET STABILIZER FOR DRYER BACKGROUND OF THE INVENTION The present invention relates to improvements in dryers and more particularly to dryers of the type used in a paper making machine having a series of rotating dryer drums over which the web is wrapped for heating the web and evaporating moisture therefrom.  
  In such dryer drums. with the increase of speed of paper making machines, one of the difficulties encountered has been flutter of the web. The flutter at times tends to be progressive and will tend to tear the sheet or at least cause uneven contact or stretching of the sheet so that nonuniform contact between the web and drum occurs resulting in nonuniform drying across the sheet. If the sheet arrives at the calender being dried nonuniformly so that excess moisture remains at certain areas across the width of the sheet, calendering will be nonuniform, and the final web wound on the take-up roll will be nonuniform making unusable, or at least a very low quality of paper.  
  The fluttering which occurs at the web edge can occur at different locations along the dryer, but will occur at any place in the web span as it travels from one drum to the other. Conventionally, the drums are arranged in tiers with the web traveling in an S shaped serpentine path between the upper and lower tiers of the dryer. The fluttering can be progressive across the sheet generally starting at the edge and is particularly disadvantageous in causing stretching of the sheet particularly if it occurs at a number of locations and a number of spans between dryer drums. As the web enters the dryer section, the moisture content decreases so that the actual weight of the web changes and fluttering can occur at various positions. Efforts to reduce this flutter have met with varying degrees of success, but have not been wholly capable of providing a simple effective means of eliminating the flutter particularly at high speeds.  
  It is accordingly an object of the present invention to provide an improved mechanism for use in a paper machine dryer section which functions to eliminate web flutter between dryer drums.  
  A still further object of the invention is to provide an improved mechanism for eliminating flutter in a paper machine dryer section between dryer drums and accomplishing the elimination of the flutter by a simple construction which does not require substantial space and can be readily installed in existing dryers.  
  While features of the invention are capable of being used to advantage in various types of machines, they are particularly useful in the environment of dryers for a paper making machine and will be described in connection with this use.  
  Other objects and advantages will become more apparent, as will equivalent structures which are intended to be covered herein, in the teaching of the principles of the invention in connection with the disclosure of the preferred embodiment in the specification, claims and drawings, in which:  
 DESCRIPTION OF THE DRAWINGS FIG. I is a front elevational view of a paper dryer constructed and operating in accordance with the principles of the present invention; and  
  FIG. 2 is a fragmentary vertical sectional view taken substantially along line IIII of FIG. 1.  
 DESCRIPTION As shown in FIG. I, a dryer section ofa paper making machine is supported on front and back frames with the front frame shown as having vertical posts 10 and II with a laterally extending beam 12 therebetween The framework at the back of the machine will be somewhat similarly constructed and need not be shown in detail. Extending between the front and back frames of the machine will be a plurality of sequentially arranged dryer drums.  
  The drawings show first, second and third drums I3, 14 and 15. The drums will be usually arranged in tiers with the drum 14 being in the upper tier and the drums l3 and 15 being in the lower tier. The upper tier of drums will be at the same horizontal elevation, and the lower tier of drums will be at the same horizontal elevation with the number of drums provided being sufficient to heat the web and evaporate the moisture therefrom which is left in the web after passing through the press section of the machine. Such machines will conventionally have or more drums. The drums will be heated usually by steam to be at a controlled temperature which is kept uniform throughout the length of the drum. The length of the drum will vary in accordance with the designed width of the paper making machine and conventionally will be approximately 24 feet to 36 feet long.  
  The web W is wrapped in serpentine fashion over the drums so as to travel in a generally S shaped path. As illustrated, the web is first wrapped over the lower drum 13 and then passes up in an upwardly extending run W-U and is wrapped over the upper drum l4 and then extends in a downward run W-D.  
  Positioned at the edges of the web W in the upwardly extending run W-U are guide means in the form of edge rolls positioned at each edge of the web. Because the rolls are of similar construction, only the roll 16 at the front edge of the machine need be shown and described in detail. The edge rolls are of limited length and do not extend completely across the machine, but extend only a short distance inwardly to contact the edge ofthe web and to deflect it a short distance D from its normal path of travel. The edge rolls can be positioned on either side of the web, but preferably on the same side as the lower roll which the web has just left. It has been discovered that by merely positioning a short roll at the edge of the web, the problems created by web flutter are avoided in that the fluttering which seems to originate at the edge of the web does not begin. Also, it is at the edge of the web that the fluttering usually results in paper web stretch to cause nonuniform drying, and this is avoided by the edge rolls. By not extending the edge rolls completely across the web, fluttering is avoided and yet unnecessary contact with the full width of the web has been eliminated. If a full width roll were used, unnecessary air flow currents would be induced and difficulties would be encountered in maintaining a roll of such a long width straight and downward bowing in such a roll would tend to have a nonequal effect on the web across its width, tending to cause wrinkling.  
  The roll is driven in rotation in a direction the same as the web travel, and it has been found that by driving the roll at a speed slower than the web travel, the tendency of the edge roll to eliminate flutter is enhanced.  
 A rotational speed of preferably 75 per cent of the speed of web travel is used and variations from 50 to I per cent of the speed of web travel also may be employed. A sliding guide may also be employed. but substantial improvement is achieved by using a rotating roll.  
  The edge rolls are supported on brackets such as shown by the bracket 17 mounted by a plate 18 to the beam l2. The plate is so constructed so as to permit lateral adjustment of the position of the edge roll and this may be accomplished by elongate slots in the plate, so that it may be adjusted by loosening tightening nuts. not shown, and shifting the plate to obtain a desired web deflection D. Preferably, the deflection D for each edge of the web is chosen to be the same.  
  Secured to the bracket [7 is an angle bracket 19 which supports the roll in cantilever fashion with the lower end of the bracket 19 shown at in FIG. 2. The roll I6 may be driven by separate motors, or may be driven by sheaves carrying belts which pass over similar edge rolls. The roll in FIG. 2 is shown equipped to be driven by a sheave 23 or by a motor 24. If the roll is to be usually driven by a sheave, the motor 24 may be re placed by a supporting bearing. Conversely, if a motor drive is usually to be used, the sheave 23 may be omitted.  
  The roll I6 comprises a tubular roll shell 16a with radial bearing plates 16d and lfie rotatably mounted on a trunnion 21. The trunnion 21 is driven in rotation by the motor 24 or by the sheave 23 which is locked to the trunnion 2|. The roll is held on the trunnion shaft by a nut 22 threaded on the end holding the plate l3e in place.  
  At the end of the roll, it is rounded in a curved shaped cone end shell 16b which is held by a screw 166 to the roll shell 16a. The roll shell 16a and the end shell 16b are polished for smooth nonabrasive contact with the web. A coating of teflon may be contained on the outer surface of the roll and end cone.  
  The length of the end roll is short relative to the width of the paper web, and a roll length of 6 inches to 4 feet may be employed. Similarly, the diameter of the roll is small relative to the dryer drums, and a diameter of 3 inches to 2 feet is satisfactory.  
  In addition to being positionably adjustable in a lateral direction to vary the deflection D, the roll may be vertically adjustable by the bracket 19 being vertically adjustable in its support I7. Where a motor drive is used, a variable speed motor is employed to control the rotational speed of the roll to approximately 75 per cent of the web speed. Where a sheave drive is used, the main driving motor driving the belt will also be variably controlled in speed.  
  While the edge rolls may be employed in all of the open draws, it has been found that by using them only in the uprunning draws, edge flutter is avoided. The rolls are simple in construction and easily manufactured and may be used on existing paper equipment as speeds of operation are increased.  
 I claim as my invention:  
  1. In a dryer for evaporating moisture from a traveling fibrous web, the combination comprising:  
 a plurality of heated dryer drums positioned in the upper and lower tiers for having a traveling web sequentially passed between the upper and lower tiers to wrap the drums for heating the web and evaporating moisture therefrom;  
 edge rolls each having an axis parallel to the drums and parallel to the web and at right angles to the direction of web travel, said rolls positioned between the upper and lower tiers at each edge of the web extending only a short distance inwardly from the web edge defiectingly supporting the web edge to reduce the tendency of the sheet to flutter at high er web travel speeds;  
 bearing means supporting said rolls;  
 and fixed supports for said bearing means fixedly locating said bearing means and fixing the position of said axes of said edge rolls.  
  2. In a dryer for evaporating moisture from a traveling fibrous web, the combination constructed in accor dance with claim I:  
 wherein the edge rolls are driven at a surface speed lower than the speed of travel of the web.  
  3. In a dryer for evaporating moisture from a traveling fibrous web. the combination constructed in accordance with claim I:  
 wherein said drums are positioned with a second drum at a higher elevation than the first drum and the edge rolls are located in the span between the first and second drum and wherein a third drum is located at a lower elevation than the second drum and the web span between the second and third drum is free from contact with any edge rolls.  
  4. In a dryer for evaporating moisture from a traveling fibrous web, the combination constructed in accordance with claim 1:  
 wherein said edge rolls have a generally rounded nose end inwardly from the edge of the web.  
  5. In a dryer for evaporating moisture from a traveling fibrous web, the combination constructed in accordance with claim 1: wherein the edge rolls have a length of no greater than 4 feet.  
  6. In a dryer for evaporating moisture from a traveling fibrous web, the combination constructed in accordance with claim 1:  
 wherein the edge rolls have a diameter in the range of 3 inches to 2 feet.  
  7. In a dryer for evaporating moisture from a traveling fibrous web, the combination constructed in accordance with claim I:  
 wherein the guide means are provided with means for adjusting their position relative to the plane of the sheet so that the distance the sheet is deflected from its normal path of travel between drums can be controlled. 8. In a dryer for evaporating moisture from a traveling fibrous web, the combination comprising:  
  a plurality of parallel heated drums positioned so that a web sequentially wraps the drums to be heated and to evaporate moisture therefrom; and guide means at each edge of the web in the web span between drums engaging the web at the edge and extending inwardly only a short distance from the web edge preventing web flutter at higher web speeds, said guide means being in the form of a roll at each edge of the web and the roll being driven at a speed ranging from 50 per cent to per cent of the web speed. 9. In a dryer for evaporating moisture from a traveling fibrous web, the combination comprising:  
 speeds.  
 said guide means being in the form of rolls at each edge of the web and the rolls being driven at a speed substantially per cent of the speed of web travel.