Suction roll for conveying a flexible strip

A suction roll for applying suction to a flexible strip wound around its circumference and conveying the strip in one direction, said suction roll comprising:

• a roll body which has inside a plurality of suction holes extending in a direction of an axis of the roll body such that the suction holes are distributed within the roll body about said axis, and the roll body has a large number of pores connecting each suction hole with a circumferential surface of the roll body;
• a shaft which protrudes from the roll body at one side, one end of each suction hole reaching a circumferential surface of the shaft;
• a negative pressure chamber formed around the shaft;
• and
• means for opening and closing the suction holes, the opening/closing means operating in accordance with rotation of the roll body to connect suction holes which communicate with pores in contact with the strip with the negative pressure chamber, and to cut off suction holes which communicate with pores out of contact with the strip from the negative pressure chamber.