Belt dewrinkling and alignment method and apparatus

A device for aligning and dewrinkling an endless belt of thin filter medium trained to travel across a drainage surface of filtration machine, which belt of filter medium does not have a bead on either of its edges, comprising:

• a. mounting means which affix the aligning and dewrinkling device rigidly to a filtration machine adjacent an edge of the traveling endless belt of filter medium;
• b. a first arm member rigidly connected to said mounting means;
• c. a first cylindrical roller and means affixing the same to said first arm member for rotation about the central axis of said first cylindrical roller;
• d. a second arm member and pivot means connecting said second arm member to said first arm member for rocking movement relative to said first arm member;
• e. a second cylindrical roller and means affixing the same to said second arm member for rotation about the central axis of said second cylindrical roller, said second cylindrical roller being mounted to said second arm member to extend above the adjacent edge of the belt of filter medium in a direction generally parallel to the plane of the belt of filter medium to define a long nip line with said first cylindrical roller along which the filter medium is gripped;
• f. biasing means connected between the ends of said first and second arm members opposite the ends to which said first and second cylindrical rollers are affixed to urge said opposite ends away from one another and, hence, to pinch said first and second cylindrical rollers together;
• and
• g. selectively actuatable pressure means mounted between the ends of said first and second arm members opposite the ends to which said first and second cylindrical rollers are affixed for selectively forcing said opposite ends away from one another.

In combination with a filtration machine having an endless belt of thin filter medium trained to travel across a drainage surface, which belt of filter medium does not have a bead on either of its edges, a pair of devices for aligning and dewrinkling the belt of filter medium across the drainage surface, each of said aligning and dewrinkling devices of said pair comprising:

• a. mounting means which affix the aligning and dewrinkling device rigidly to the filtration machine adjacent an edge of the traveling endless belt of filter medium;
• b. a first arm member rigidly connected to said mounting means;
• c. a first cylindrical roller and means affixing the same to said first arm member for rotation about the central axis of said first cylindrical roller, said first cylindrical roller being mounted to said first arm member to extend beneath the adjacent edge of the belt of filter medium in a direction generally parallel to the plane of the belt of filter medium;
• d. a second arm member and pivot means which connects said second arm member to said first arm member for rocking movement;
• e. a second cylindrical roller and means affixing the same to said second arm member for rotation about the central axis of said second cylindrical roller, said second cylindrical roller being mounted to said second arm member to extend above the adjacent edge of the belt of filter medium in a direction generally parallel to the plane of the belt of filter medium to define a long nip line with said first cylindrical roller along which the filter medium is gripped;
• and
• f. selectively actuatable pressure means mounted between the ends of said first and second arm members opposite the ends to which said first and second cylindrical rollers are affixed for selectively forcing said opposite ends away from one another and, hence, to urge said second arm member to rock so as to pinch said first and second cylindrical rollers together.

A method for aligning and dewrinkling an endless belt of filter medium trained to travel across a drainage surface, which belt of filter medium does not have a bead formed on either of its edges, comprising the following steps:

• a. on each side of the belt of filter medium, gripping the belt from above and below with two generally parallel cylindrical rollers where the longitudinal axes of the rollers are at an angle with respect to the direction of travel of the belt and where the cylindrical rollers are connected for rotation to first and second arm members, respectively, which are connected at a fulcrum point for rocking movement one toward the other;
• b. sensing the lateral position of the belt of filter medium with two sensors fixed adjacent the two opposite edges of the belt;
• and
• c. forcing the two arm members to pivot to force the rollers toward one another to grip the belt of filter medium according to the lateral position of the filter medium belt determined by said sensor means.