Method and structure for separating the web material in a winding machine

A structure for separating a web material in a winding machine comprising an upper winding roller, at least one guide plate, a lower winding roller, and a rider roller, wherein the guide plate is arranged at a location close to and below the upper winding roller and forms a channel with the upper winding roller, the upper winding roller, the lower winding roller, and the rider roller forming therebetween a winding nip, a web material being fed into and passing through the channel to form a paper roll in the winding nip by being wound around a first core, a separation mechanism being arranged at a location close to and below the upper winding roller, the separation mechanism comprising:

• a pivot shaft having an outer circumferential surface;
• at least one pinch arm coupled to the outer circumferential surface of the pivot shaft, the pinch arm having a connecting end and a web engagement end, the connecting end being fixedly mounted to the outer circumferential surface of the pivot shaft, the web engagement end extending outward from the outer circumferential surface of the pivot shaft and forming at least one suction opening;
• a driving mechanism connected to the pivot shaft to drive the pinch arm to rotate about the pivot shaft to position the web engagement end of the pinch arm periodically at an engagement position opposing the upper winding roller, the web engagement end of the pinch arm at the engagement position engaging the web material without bearing against the upper winding roller, the web engagement end at the engagement position maintaining a predetermined spacing from the upper winding roller, such that the pinch arm does not contact the upper winding roller;
• a suction channel formed inside the pivot shaft and communicating with the suction opening of the web engagement end through a passage;
• and
• an evacuation device connected to the pivot shaft and communicating with the suction channel to form a vacuum suction force at the suction opening of the web engagement end of the pinch arm;
• wherein when the pinch arm is driven by the driving mechanism to position the web engagement end of the pinch arm at the engagement position, the suction opening of the web engagement end of the pinch arm sucks and holds the web material disposed in the channel against the web engagement end, whereby the web material is subjected to a pulling force induced by the paper roll formed in the winding nip to tear and separate at a location between the engagement position and a position of the paper roll of the first core;
• and,
• wherein the pinch arm is rotatable in a direction opposite to the predetermined rotation direction of the upper winding roller.