Velocity-changing apparatus for web

A method for processing a continuous web for composing a disposable worn article comprising the steps of:

• feeding the continuous web at a feed velocity to a rotating drum from a movable member, the rotating drum having a circumferential surface and a circumferential velocity;
• transporting the continuous web by the rotating drum at a transport velocity, the continuous web contacting and winding around at least a portion of the circumferential surface of the rotating drum, wherein the transport velocity is generally equal to the circumferential velocity of the rotating drum;
• changing the circumferential velocity of the rotating drum periodically at least once per rotation of the drum;
• moving the movable member according to the change of the circumferential velocity of the drum to feed the continuous web to the rotating drum so that the feed velocity is generally equal to the transport velocity of the continuous web as it is being transported by the rotating drum;
• and
• welding the continuous web with a welder on the rotating drum when the transport velocity is lower than an average circumferential velocity of the drum, wherein in the step of welding the continuous web, an ultrasonic welding is carried out onto the continuous web with an ultrasonic energy applied onto the continuous web, and
• further comprising a step of cutting the continuous web with a cutter on the rotating drum to form at least one cut-off web when the transport velocity is lower than the average circumferential velocity of the drum, wherein the step of cutting the continuous web is carried out when the step of welding the continuous web is carried out.