Belt and drum-type press with supplemental nip loading means

A drum and belt-type press for compressing a moving web or mat which comprises:

• (a) a supporting frame for a drum, belt tensioning rolls, and belt tensioning means;
• (b) a pair of spaced apart first and second shaft mounted cylindrical belt tensioning rolls having essentially parallel axes of rotation;
• (c) a central drum adjacent said tensioning rolls, said drum having an axis of rotation essentially parallel to the axis of rotation of the rolls;
• (d) an endless flexible belt having an inner generally U-shaped course and an outer generally U-shaped course, the inner and outer courses meeting in loops which wrap around the tensioning rolls,
• the tensioning rolls each being contained within the body of the belt and the drum being outside the body of the belt, the inner course of the belt being wrapped around more than half the circumference of the central drum,
• the tensioning rolls and drum being sized so that the inner and outer courses of the belt are spaced apart,
• each tensioning roll and any other rolls within the belt making nip contact with the drum through the interposed belt so that the total compressive forces of the belt and nips on the central drum are balanced and the summation of forces about the drum axis is essentially zero;
• (e) drive means for moving the belt through its endless path, so that a web or mat may be compressed by interposing it between the moving belt and drum;
• (f) tensioning means acting on the tensioning rolls to translate them relatively toward or away from each other to control belt tension while maintaining nip contact;
• (g) the tensioning rolls being mounted on the supporting frame, the drum being free floating with respect to the tensioning rolls for relative radial movement in response to tensioning adjustments, and the press is structured to maintain nip contacts without transmitting significant belt tensioning forces to the supporting frame or significant axial bending moment to the drum;
• (h) at least one shaft mounted idler nip roll enclosed within the flexible belt body between the first and second tensioning rolls, the idler nip roll or rolls being radially movable by the outer course of the belt and forming nips with the central drum through the interposing belt when said belt is in tension, the belt, idler nip rolls, and tensioning rolls all being in a balanced force relationship with the drum;
• and
• (i) one or more of said idler nip roll or rolls having supplemental force means acting on its support shaft to create a nip force of the idler nip roll with the drum, independent of the nip force created by the tension of the endless belt, the press is structured and arranged so that the net resultant force of all idler nip forces from all sources passes between the centers of rotation of the first and second tensioning rolls, pivotally connected support bars providing support from the first and second belt tensioning roll shafts to the supplemental force means, said support bars being aligned on drum radial lines through said first and second tensioning roll centers of rotation, the orientation of said support bars serving to avoid any material impact of supplemental nip roll loading on said belt tensioning means.

A drum and belt-type press for compressing a moving web or mat which comprises:

• (a) a supporting frame for a pair of nip rolls and a belt tensioning means;
• (b) first and second fixed spaced apart shaft mounted rotatable nip rolls mounted on the frame to form an assembly, said rolls having parallel axes of rotation;
• (c) a central drum adjacent the nip rolls, the drum having an axis of rotation essentially parallel to the nip rolls;
• (d) at least one shaft mounted idler roll having limited freedom of movement generally radial to the drum also located adjacent the drum;
• (e) an endless flexible belt having an inner generally U-shaped course and outer generally U-shaped course, the inner and outer courses meeting in loops, one loop containing the first fixed nip roll and the other loop containing the second fixed nip roll,
• the fixed nip rolls and said movable idler nip roll or rolls being located within the body of the belt, the inner course of the belt being wrapped around more than one half of the circumference of the drum so that all the nip rolls make nip contact with the drum through the interposed belt,
• the drum, fixed nip rolls and idler nip rolls being sized to hold the inner and outer courses of the belt in spaced apart relationship;
• (f) at least one moveable belt tensioning roll mounted to act against the belt to control belt tension, said tensioning roll or rolls not making nip contact with the drum;
• (g) tension control means to adjust the tensioning rolls;
• (h) means for rotating the belt through its endless path to compress a web or mat interposed between the moving belt and drum,
• the drum being free to move radially to the fixed nip rolls or the nip roll and frame assembly being free to move to the drum so that the nip rolls act through the belt against the drum with a force controlled by belt tension;
• and
• (i) supplemental force means acting on the support shaft of one or more of the idler nip rolls to create a nip force of the idler nip roll or rolls with the drum, independent of the nip force created by the endless tension belt,
• pivotally connected support bars connected to the supporting frame for the first and second fixed spaced apart nip rolls to provide support for the supplemental force means,
• the press being structured and arranged so that the next resultant force on the drum resulting from all idler nip roll nip forces passes between the centers of rotation of the first and second fixed spaced apart nip rolls.

A drum and belt-type press for compressing a moving web or mat which comprises:

• (a) a supporting frame;
• (b) first and second spaced apart rotatable nip rolls movably mounted on the frame, said rolls having parallel axes of rotation, the first roll positioned as a belt entry nip roll and the second roll positioned as a belt exit nip roll;
• (c) a central drum adjacent the first and second nip rolls, said drum being shaft mounted in the frame in a fixed location and having an axis of rotation essentially parallel to said nip rolls and located so that the movably mounted first and second nip rolls may freely nip with the central drum;
• (d) at least one idler nip roll having limited freedom of movement generally radial to the drum also being located adjacent the drum;
• (e) an endless flexible belt having an inner generally U-shaped course and an outer generally U-shaped course, the inner and outer courses meeting in loops, one loop containing the first nip roll and the other loop containing the second nip roll, the inner course of the belt being wrapped around more than one half of the circumference of the drum, said first and second nip rolls being located within the body of the belt, said idler nip roll or rolls also being located within the body of the belt between the first and second nip rolls, all of the nip rolls making nip contact with the drum through the interposed inner course of the belt;
• (f) at least one belt guide roll being located within the body of the belt to support the outer course of the belt, said guide roll or rolls not making nip contact with the drum, the location and sizes of the guide roll or rolls and the nip rolls acting to maintain clearance between the outer course of the belt and the inner course of the belt;
• (g) tensioning means to control belt tension;
• (h) supplemental loading means for one or more of said idler nip roll or rolls, to create a desired nip force for said idler nip roll or rolls acting upon the drum, independent of belt tension, the location of all said idler nip rolls and the nature of the forces they exert on the drum being such and the press being constructed and arranged such that the net resultant force of all idler nip roll forces upon the drum is directed between the centers of rotation of the first and second idler nip rolls, said first and second nip rolls being shaft mounted and the loading means of at least one of said idler nip roll or rolls being supported from the shafts of said first and second nip rolls;
• and
• (i) driving means for rotating the belt through its endless path so as to compress a web or mat interposed between the moving belt and drum.