Patent Publication Number: US-4546698-A

Title: Mill roll with increased juice flow capacity

Description:
BACKGROUND OF THE INVENTION 
     A conventional sugar cane mill includes a top roll and at least one bottom roll associated therewith so that a sugar cane blanket is milled between them to squeeze the juice from the blanket. A substantial amount of the juice squeezed from the cane tends to become trapped in the blanket and reabsorbed after the blanket passes between the top and bottom rolls. This led to the invention described and claimed in my prior U.S. Pat. No. 3,969,802 wherein at least one of the rolls is formed with a plurality of holes opening from circumferentially extending grooves into a plurality of axial channels within the body of the roll, so that juice squeezed from the cane blanket flows through the holes and then axially out through the channels. Mill rolls constructed in accordance with that invention have enjoyed considerable commercial success, but limitations on the number of holes and axial channels restrict the amount of juices that can be accommodated. 
     OBJECTS OF THE INVENTION 
     It is an object of this invention to provide a mill roll with perforations opening from the surface into lateral flow passages, all of increased flow capacity. 
     It is a further object of this invention to provide a mill roll having lateral flow passages of substantial flow area with considerable crushing structural strength. 
     Other objects and advantages of this invention will become apparent from the description to follow, particularly when read in conjunction with the accompanying drawings. 
     SUMMARY OF THE INVENTION 
     In carrying out this invention, I have modified the mill roll disclosed in my aforesaid prior U.S. Pat. No. 3,969,802 so that the lateral juice flow passages are disposed spirally, rather than axially, whereby the beam loading imposed by the cane blanket crushed between the rolls at the line of maximum compression between them is not taken along the full length of a channel as in the aforesaid patent. This enables the provision of wider or more numerous channels providing greater flow capacity, which in turn, can accommodate more radial holes opening from the surface of the roll into the circumferential grooves. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     In the drawings: 
     FIG. 1 is a top view in perspective of a three roll mill incorporating this invention; and 
     FIG. 2 is a view in perspective of a mill roll constructed in accordance with this invention. 
    
    
     DESCRIPTION OF A PREFERRED EMBODIMENT 
     Referring now to FIG. 1 with greater particularity, a typical sugar cane mill 10 may include a top roll 12 and two bottom rolls 14 and 16, which rotate as indicated by the arrows so that sugar cane or bagasse is fed into the mill at 18 to pass between the top roll 12 and right bottom roll 14, where the sugar cane blanket is crushed between them to squeeze juice out and into a suitable receptacle 20 for processing. The cane blanket then passes across a trash plate 22 to enter between the rolls 12 and 16 where additional juices are extracted. 
     In accordance with my prior invention, one or more of the rolls may be provided with a plurality of circumferential, Vee grooves 24 across the surface thereof and holes 26 at the bottoms of the grooves open into axial passageways 28 that extend the length of the roll so that additional juices squeezed from the cane blanket flow into the holes 26 and along the longitudinal passageways 28 to exit at the ends of the rolls, greatly increasing the extraction of juices from sugar cane, or liquids from pulp in any event. 
     Generally, one of the rolls, usually the top roll 12 in a three mill roll as shown, is provided with flanges 30 at the ends which extend over the ends of the bottom rolls 14 and 16 in the areas of maximum pulp compression to prevent extrusion of the bagasse from the sides of the mill 10. In some cases, stationary plates on the machine function as the flanges. Unfortunately, in whatever form, the flanges 30 also tend to block the ends of the longitudinal passageways to limit the capacity of the longitudinal juice ducts 28 when same are provided in the bottom rolls. 
     As shown in FIG. 2, this disadvantage is overcome in the present invention by forming the end to end passageways 28 of spiral configuration. When the bagasse is being squeezed between the bottom roll 14 and the top roll 12 in the area of maximum compression along the dashed line A in FIG. 2, the juice that is squeezed into holes 26 at that level follows the spiral configuration of the flow passage to exit at approximately point B, well clear of the restraining flange of the upper roll 30. This spiral configuration of the passageways has been tested and found highly effective with passageways that curve from one end of the roll 14 to the other. 
     An additional advantage of the spiral configuration will become apparent from FIG. 2. As the roll passes through the line of maximum compression A the metal of the roll 14 radially outward of the passageways 28 is supported along its length by the columns of metal 29 between the passageways, so that there is a plurality of short columns along the length of the roll and no unsupported metal from end to end, as in the case of axially disposed flow passages. This minimizes the chances of fracture, and enables the application of higher compression pressures between rolls, as well as the provision of wider channels. Of course, wider channels 28 can accommodate a larger number of holes or perforations 26, further to increase flow capacity. 
     In the event a roll does become worn after extended use, it may be machined down to the tops of the spiral columns 29, and a sleeve with the circumferential Vee grooves 24 and perforations 26 secured in place over it. 
     While this invention has been described in conjunction with a preferred embodiment thereof, it is obvious that modifications and changes therein may be made by those skilled in the art to which it pertains, without departing from the spirit and scope of this invention as defined by the claims appended hereto.