Paper web threading apparatus and method for threading a paper web through a papermaking machine

摘要

A paper web threading apparatus is provided for a papermaking machine. The threading apparatus includes a transfer sheave assembly mounted on an end of a middle rotating drum disposed between an upstream drum and a downstream drum. The transfer sheave assembly includes a first sheave that is fixed to the middle drum and rotates with the middle drum and a second sheave that rotates freely and independently of the middle drum. An upstream pair of endless ropes is provided that wrap partially around the sheave of the upstream drum before wrapping partially around one of the sheaves of the transfer sheave assembly. A pair of downstream endless ropes is also provided that wrap partially around the other of the sheaves of the transfer sheave assembly as well as the sheave mounted to the downstream drum. The upstream ropes maintain an adjacent position with respect to each other until they depart from the transfer sheave assembly. The downstream ropes maintain a diverged positional relationship with respect to each other until they engage the transfer sheave assembly and form a nip point. Thus, the upstream pair of endless ropes maintain a closely adjacent positional relationship until they pass the nip point. As a result, the tail or leading edge of a paper web can be effectively transferred from the upstream pair of endless ropes to the downstream pair of endless ropes.