Abstract:
The present invention relates to a singlefacer or doublebacker belt having a endless spiral-link base structure. The base structure includes a top surface and a bottom surface, and further includes a plurality of side-by-side metal spirals, each spiral defining an internal space, wherein the spirals are interconnected by a series of parallel pintles extending through the internal spaces of adjacent spirals.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to corrugated paper board manufacture and to the belts required by the machines used to manufacture that variety of paper board. More specifically, the present invention relates to the belts that may be used on the singlefacer and/or doublebacker sections of a corrugated board production line.  
         [0003]     2. Description of the Prior Art  
         [0004]     In the manufacture of corrugated paper board, a so-called core paper is heated by steam, which makes it more pliable, and is then fed into a nip formed between a pair of toothed rollers whose teeth mesh, thereby corrugating the core paper in a uniform, undulating pattern. Starch paste is subsequently applied to the crests of the corrugated core paper, which is then mated to a liner paper in a press nip. There, the corrugated core paper and liner paper are bonded together to form a completed sheet, which can then be further processed as desired.  
         [0005]     In one machine used for this purpose in the prior art, the press nip is formed by one of the toothed or corrugating rolls and a pressure roll. In another machine of a more recent design, the press nip is extended in the running direction through the use of a belt instead of a pressure roll. The belt holds the corrugated core paper and liner paper together against the corrugating roll for a significant portion of its circumference.  
         [0006]     The belt experiences severe operating conditions. Because heat is used to vaporize moisture in the core paper, the belt operates in a high-temperature environment. Further, the belt continually runs, albeit with the corrugated board sheet between, against the teeth on the corrugating roll to develop the required bonding pressure between the core paper and the liner paper. Moreover, the belt must be flexible yet have lengthwise strength and widthwise rigidity sufficient to withstand wrinkling, which may cause the belt to drift undesirably from side to side.  
         [0007]     Some prior art singlefacer belts are constructed of a woven base fabric, usually of synthetic yarns, and a surface of fiber applied by needling. In addition, some belts may be just the woven structure with no needled batt fiber. Either type of belt can have a coating or a resin impregnation for added abrasion resistance or to enhance other belt characteristics. Note that a woven metal fabric with brazed or similar seam is also common. While the synthetic construction provides advantages in some applications and with certain belt configurations, this construction may result in low wear resistance, poor strength, limited heat conduction, and the probability of separation of the base from the cover. As to belts of metal construction, oftentimes there is inherent weakness in the seam.  
         [0008]     Also as to doublebacker belts, they are typically constructed of synthetic yarns, woven and sometimes subsequently needlepunched, and also synthetic monofilament yarns made into spiral-link fabrics. Again, while such belts provide advantages in some applications and with certain belt configurations, they may suffer from low wear resistance, insufficient permeability, poor seam strength, and the probability of seam marking. Similarly with synthetic spiral-link fabrics, they may result in low wear resistance, inferior strength, and a less than desirable weight per unit area.  
         [0009]     While the foregoing have attendant advantages as aforenoted, further improvements and/or alternative forms, are always desirable. Accordingly, the present invention provides an improvement and/or solution to the problems inherent in the use of a belt of the foregoing varieties.  
       SUMMARY OF THE INVENTION  
       [0010]     It is the object of the present invention to provide an improved belt for use in the manufacture of corrugated paper board.  
         [0011]     It is a further object of the present invention to provide a belt with improved strength, wear resistance, and heat conduction.  
         [0012]     It is a further object of the present invention to provide a belt that demonstrates improved wear resistance, permeability, and seam strength.  
         [0013]     These and other objects and advantages are provided by the present invention. In this regard, the present invention is directed towards a singlefacer belt having an endless base structure with a top surface and a bottom surface. The base structure is formed by a plurality of side-by-side metal spirals. Each spiral defines an internal space, and the spirals are interconnected by a series of parallel metal pintles extending through the internal spaces of adjacent spirals.  
         [0014]     The present invention is also directed towards a doublebacker belt having an endless base structure with a top surface and a bottom surface. The base structure is formed by a plurality of side-by-side metal spirals. Each spiral defines an internal space, and the spirals are interconnected by a series of parallel pintles extending through the internal spaces of adjacent spirals.  
         [0015]     The various features of novelty which characterize the invention are pointed out in particularity in the claims annexed to and forming a part of this disclosure. 
     
    
     BRIEF DESCRIPTION OF THE FIGURES  
       [0016]     For a more complete understanding of the invention, reference is made to the following description and accompanying drawings, in which:  
         [0017]      FIG. 1  shows a typical belted singlefacer corrugated board production line;  
         [0018]      FIG. 2  is a plan view of a section of the metal spiral-link base structure for the singlefacer or doublebacker belt according to the present invention;  
         [0019]      FIG. 3  is a cross sectional view of the metal spiral-link base structure shown in  FIG. 2 , according to the present invention; and  
         [0020]      FIGS. 4A and 4B  show doublebacker corrugated board machines utilizing the belts of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0021]     Turning now to these figures,  FIG. 1  is a schematic view of a typical belted singlefacer section  10  of a corrugated board production line. A core paper  12 , previously exposed to steam which makes it more pliable, is fed continuously between a pair of cooperating rolls  14 ,  16 . The rolls  14 ,  16  have uniformly spaced, peripheral teeth  18 ,  20 , which mesh as the rolls  14 ,  16  rotate about their respective, parallel axes  22 ,  24 . The meshing teeth  18 ,  20  produce corrugations  26  in the core paper  12 .  
         [0022]     A coating mechanism  28  applies a starch paste  30  to the crests  32  of the corrugations  26  in the core paper  12 .  
         [0023]     The corrugated core paper  12  is continuously applied to a liner paper  34  at point  36 , where a belt  40 , which is trained around a pair of spaced rollers  42 ,  44 , passes around roller  42 . The spaced rollers  42 ,  44  are so disposed that belt  40  bears against roll  16 , and both may form nips with roll  16 , so that the belt  40 , trained thereabout, bears against roll  16  for the entire interval between spaced rollers  42 ,  44  forming an extended nip between roll  16  and belt  40 . Heat is applied to the corrugated core paper  12  and liner paper  34  through at least one of the rollers  42 ,  44 , belt  40  and roll  16 . The heat vaporizes water absorbed by the corrugated core paper  12  when the corrugated core paper  12  was exposed to steam and dries the starch paste  30 .  
         [0024]     The rollers  42 ,  44  are situated so that the teeth  20  on roll  16  bear against the outside surface of the belt  40  over a substantial circumferential extent as the system operates. The teeth  20  maintain the proper registration of the corrugated core paper  12  as it is advanced. At the same time, the roll  16  firmly presses the side of the core paper  12  with the paste thereon against the liner paper  34  to effect bonding there between. The corrugated core paper  12  with the liner paper  34  attached thereto exits as a singleface product  46  from between the roll  16  and the roller  44 .  
         [0025]     In one embodiment, the belt of the present invention may be a singlefacer belt used on, for example, the above described corrugator board machine. In this connection,  FIG. 2  is a plan view illustrating a portion of a metal spiral-link base  1  which forms part of the belt according to the present invention. As can be seen, the metal spiral-link base  1  is constituted of oppositely oriented axially extending spirals  2 ,  4 . In  FIG. 2 , spirals  2  are oriented in one direction, for example, with their upper portions being inclined leftwardly, while spirals  4  are oriented oppositely, for instance, with their upper portions inclined to the right between spirals  2 .  
         [0026]     The metal spirals  2  and  4  extend along parallel longitudinal axes. Referring now to  FIG. 3 , the spirals  2  and  4  define longitudinally extending internal passages  6 ,  8 , respectively. As can be seen, spirals  2  and  4  are arranged to overlap each other, so that the end portions of internal spaces  6 ,  8  overlap. In this connection, pintles  3  extend through the overlapping portions of the spiral internal spaces  6 ,  8 , to connect spirals  2  and  4  into a continuous material.  
         [0027]     The helical spiral-link base  1  of the belt may be produced from a variety of metal materials. While stainless steel is most common, other metals suitable for the purpose can be used, especially if certain properties are desired. Also, while the metal material which forms the spirals  2 ,  4  can be round in cross section, flat spirals or other shapes suitable for the purpose can be utilized. In addition, the spirals  2 ,  4  can be interlaced or non-interlaced, and the spacing between the turns of a respective spiral can be wider or narrower as desired. Finally, it is noted that filler means, for example, a plurality of flat bars (not shown) or other elements suitable for the purpose, can be disposed within the spirals  2 ,  4  with a view to varying the permeability or surface condition of the inventive belt.  
         [0028]     As described above, the use of the metal spiral-link base  1  to form a belt enables the present invention to provide improved operation and other advantages. For example, the singlefacer belt of the invention offers better wear resistance, greater strength and better heat conduction than prior synthetic belts, as well as stronger seams than prior art woven metal fabrics having brazed or similar seams.  
         [0029]     In a second embodiment, the inventive belt with metal spiral-link base  1  can be a doublebacker belt used on the doublebacker section shown in  FIGS. 4A and 4B . The corrugator machine  50  in  FIG. 4A  has an upper belt  52  and a lower belt  54  which together pull a corrugated paper product  56  therethrough. Corrugated paper product  56  includes a corrugated layer  58  and an uncorrugated layer  60 , which are joined to one another in the machine  50  by means of a suitable adhesive. Layers  58  and  60  are brought together at one end of the machine  50  and are pulled by belt  52  across a series of hot plates  62  to dry and/or to cure the adhesive which bonds the paper layers together.  
         [0030]     After passing over hot plates  62 , the upper and lower belts  52 ,  54  together pull the corrugated paper product  56  between them, maintaining the speed of the operation and cooling the paper product  56 . Weighted rollers  66  apply pressure from within the endless loops formed by belt  52  and belt  54  toward one another, so that corrugated paper product  56  may be held therebetween firmly. Upon exit from between the upper and lower belts  52 ,  54 , the corrugated paper product  56  is cut and/or stacked as required.  
         [0031]      FIG. 4B  shows a doublebacker section in which the upper belt  52  is replaced with a much shorter belt  72 . In this case, the upper belt  72  does not pass across the hot plates  62 . Instead, the upper belt  72  is disposed opposite the lower belt  54  downstream from hot plates  62  in what may be referred to as cooling, or pulling, zone  74 .  
         [0032]     In this variety of corrugator machine  70 , weighted steel shoes push the corrugated paper product  56  against the hot plates  62 . In this case, the upper and lower belts  72 ,  54  disposed downstream from hot plates  62  pull the corrugated paper product  56  through the machine  70 . As before, weighted rollers  66  apply pressure from within the endless loops formed by belt  72  and belt  54  toward one another, so that corrugated paper product  56  is firmly held therebetween. Again, upon exit from between belts  52 ,  54 , the corrugated paper product  56  is cut and/or stacked.  
         [0033]     Accordingly, when used on the above described corrugator machines, the doublebacker belt of the present invention exhibits better wear resistance, improved permeability and greater resistance to seam marking than prior woven synthetic belts, as well as better wear resistance, greater strength and improved weight per unit area as compared with prior synthetic spiral-link fabrics.  
         [0034]     It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efficiently attained and, because certain changes may be made in carrying out the above method and in the construction(s) set forth without departing from the spirit and scope of the invention, it is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.