Sheet supply method and sheet supply device

Abstract

A sheet supply method includes an unwinding step of supplying a sheet to a downstream location at a predetermined conveyance speed and a joining step of joining the sheet from a first roll to the sheet of a second roll and cutting the sheet from the first roll at an upstream position of a joining section. In the joining step, the running speed of the sheet run from the first roll is made lower than the predetermined conveyance speed in the unwinding step, and different from a supply speed of the sheet from a supply part in the joining step. An accumulating mechanism decelerates or accelerates the sheet running to counterbalance an excess or a deficiency of the sheet which is caused by a speed difference between the running speed and the supply speed.

1 . A sheet supply method for sequentially unwinding a sheet from a first roll of sheet and a second roll of sheet for sheet supply by using a sheet supply apparatus including: a first support shaft which rotatably supports the first roll of sheet at a center position thereof; a second support shaft which rotatably supports the second roll of sheet at a center position thereof: a joining mechanism which joins the sheet of the second roll and the sheet of the first roll to each other; a supply part which supplies the sheet run from the first roll or the second roll to a downstream location; and an accumulating mechanism which is provided between the first support shaft and the supply part, and accumulates a predetermined length of sheet by receiving an upstream portion of the sheet, the sheet supply method comprising:
 an unwinding step of controlling the first support shaft to supply the sheet from the supply part to the downstream location at a predetermined conveyance speed set for an apparatus in the downstream location; and   a joining step of controlling the first support shaft, the second support shaft, and the joining mechanism to join the sheet from the first roll to the sheet of the second roll by pressing an intermediate portion of the sheet run from the first roll onto an outer peripheral surface of the second roll in a condition where a running speed of the sheet from the first roll coincides with a moving speed of the outer peripheral surface of the second roll, and to cut the sheet from the first roll at an upstream position of a joining section where the sheet from the first roll has been joined to the sheet of the second roll, wherein   in the joining step, the first support shaft is controlled to make the running speed of the sheet run from the first roll lower than the predetermined conveyance speed in the unwinding step, and different from a supply speed of the sheet from the supply part in the joining step, thereby causing the accumulating mechanism to decelerate or accelerate the sheet running to counterbalance an excess or a deficiency of the sheet which is caused by a speed difference between the running speed of the sheet from the first roll and the supply speed of the sheet from the supply part.   
     
     
         2 . A sheet supply method according to  claim 1 , wherein
 in a case where the sheet supply from the supply part to the downstream location is suspended in the joining step, the first support shaft, the second support shaft, and the joining mechanism are controlled so that the intermediate portion of the sheet run from the first roll is pressed onto the outer peripheral surface of the second roll in the condition where the running speed of the sheet from the first roll coincides with the moving speed of the outer peripheral surface of the second roll, thereby causing the accumulating mechanism to receive and accumulate the excess of the sheet which is caused by the speed difference between the running speed of the sheet run from the first roll and the supply speed of the sheet from the supply part.   
     
     
         3 . A sheet supply method according to  claim 1 , wherein
 in the joining step, prior to the sheet joining, the first support shaft is controlled to wind up the sheet onto the first roll until an accumulated length of the sheet in the accumulating mechanism comes to a minimum in advance.   
     
     
         4 . A sheet supply method according to  claim 1 , wherein
 in the joining step, the first support shaft, the second support shaft, and the joining mechanism are controlled so that the intermediate portion of the sheet of the first roll is pressed onto the outer peripheral surface of the second roll in a condition where the unwinding of the sheet from the first roll is suspended and rotation of the second roll is stopped, and the first roll and the second roll rotate thereafter.   
     
     
         5 . A sheet supply apparatus for sequentially unwinding a sheet from a first roll of sheet and a second roll of sheet for sheet supply, the sheet supply apparatus comprising:
 a first support shaft which rotatably supports the first roll at a center position thereof;   a second support shaft which rotatably supports the second roll at a center position thereof;   a joining mechanism which joins the sheet of the second roll and the sheet of the first roll to each other, and includes a cutter for cutting the sheet run from the first roll at an upstream position of a joining section where the sheets have been joined to each other after the sheet joining;   a supply part which supplies the sheet run from the first roll or the second roll to a downstream location of the sheet supply apparatus;   a controller which controls the first support shaft to supply the sheet from the supply part to the downstream location at a predetermined conveyance speed set for an apparatus in the downstream location in an ordinary operation where the sheet is supplied from the sheet supply apparatus to the downstream location, and controls the first support shaft, the second support shaft, and the joining mechanism to press an intermediate portion of the sheet run from the first roll onto an outer peripheral surface of the second roll in a condition where a running speed of the sheet from the first roll coincides with a moving speed of the outer peripheral surface of the second roll for the sheet joining; and   an accumulating mechanism which is provided between the first support shaft and the supply part, and accumulates a predetermined length of sheet by receiving an upstream portion of the sheet, wherein   the controller controls the first support shaft to make the running speed of the sheet from the first roll lower than the predetermined conveyance speed for the sheet joining, and different from a supply speed of the sheet from the supply part for the sheet joining, thereby causing the accumulating mechanism to decelerate or accelerate the sheet running to counterbalance an excess or a deficiency of the sheet which is caused by a speed difference between the running speed of the sheet from the first roll and the supply speed of the sheet from the supply part.   
     
     
         6 . A sheet supply apparatus according to  claim 5 , wherein
 in a case where the sheet supply from the supply part to the downstream location is suspended, the controller controls the first support shaft, the second support shaft, and the joining mechanism to press the intermediate portion of the sheet run from the first roll onto the outer peripheral surface of the second roll in the condition where the running speed of the sheet from the first roll coincides with the moving speed of the outer peripheral surface of the second roll.   
     
     
         7 . A sheet supply method according to  claim 2 , wherein
 in the joining step, prior to the sheet joining, the first support shaft is controlled to wind up the sheet onto the first roll until an accumulated length of the sheet in the accumulating mechanism comes to a minimum in advance.   
     
     
         8 . A sheet supply method according to  claim 2 , wherein
 in the joining step, the first support shaft, the second support shaft, and the joining mechanism are controlled so that the intermediate portion of the sheet of the first roll is pressed onto the outer peripheral surface of the second roll in a condition where the unwinding of the sheet from the first roll is suspended and rotation of the second roll is stopped, and the first roll and the second roll rotate thereafter.   
     
     
         9 . A sheet supply method according to  claim 3 , wherein
 in the joining step, the first support shaft, the second support shaft, and the joining mechanism are controlled so that the intermediate portion of the sheet of the first roll is pressed onto the outer peripheral surface of the second roll in a condition where the unwinding of the sheet from the first roll is suspended and rotation of the second roll is stopped, and the first roll and the second roll rotate thereafter.