Sheet supply device and sheet supply method

A sheet supply device for supplying a sheet from a first roll and a second roll around which the sheet is wound, the sheet supply device comprising:

• a first support shaft that supports the first roll at a center position thereof;
• a second support shaft that supports the second roll at a center position thereof;
• a joining mechanism that joins the sheet of the second roll to the sheet of the first roll;
• and
• a controller that controls driving of the joining mechanism such that the sheet of the first roll is joined to the sheet of the second roll when a remaining quantity of the sheet of the first roll is equal to or less than a preset remaining quantity in a state in which the sheet of the first roll is supplied,
• wherein the joining mechanism includes a second shaft drive source that rotatably drives the second support shaft, a pressing roller that is provided so as to be relatively displaceable with respect to the second support shaft in a direction orthogonal to the second support shaft, and a servomotor that drives the pressing roller so as to press the sheet of the first roll against an outer peripheral surface of the second roll, and
• the controller includes a shaft control unit that controls driving of the second shaft drive source such that the second roll is rotated, and a motor control unit that presses the pressing roller against the outer peripheral surface of the second roll via the sheet of the first roll by performing torque control on the servomotor in a state in which the pressing roller is positioned in an area from a control switching position to the outer peripheral surface of the second roll together with performing position control on the servomotor in a state in which the pressing roller is positioned in an area farther away from the second roll than the control switching position that is away from the outer peripheral surface of the second roll by a preset distance while the second roll is rotated by the shaft control unit
• wherein the controller switches control of the servomotor from the position control to the torque control in a state in which driving of the servomotor is maintained when the pressing roller approaches the second roll beyond the control switching position from the area farther away from the second roll than the control switching position.

A sheet supply method for supplying a sheet from a first roll and a second roll around which the sheet is wound, the sheet supply method comprising:

• a first supply step of supplying the sheet of the first roll supported at a center position by a first support shaft;
• and
• a joining step of joining the sheet of the second roll to the sheet of the first roll using a joining mechanism that joins the sheet of the second roll to the sheet of the first roll when a remaining quantity of the sheet of the first roll is equal to or less than a preset remaining quantity in a state in which the sheet of the first roll is supplied,
• wherein the joining mechanism includes a second shaft drive source that rotatably drives the second support shaft, a moving unit carrying a pressing roller, a unit drive mechanism having a servomotor for driving the moving unit so as to relatively move with respect to the second support shaft in a direction orthogonal to the second support shaft, and wherein the servomotor drives the moving unit carrying the pressing roller so that the pressing roller presses the first roll against an outer peripheral surface of the second roll, and
• in the joining step, the pressing roller is pressed against the outer peripheral surface of the second roll via the sheet of the first roll by performing torque control on the servomotor in a state in which the pressing roller is positioned in an area from the control switching position to the outer peripheral surface of the second roll together with performing position control on the servomotor in a state in which the pressing roller is positioned in an area farther away from the second roll than a control switching position that is away from the outer peripheral surface of the second roll by a preset distance while the second roll is rotated by the second shaft drive source.