Yarn positioning mechanism of an automatic traveling package doffer

摘要

An automatic package doffer of a textile winding machine includes a yarn engaging device and a travel limiting device. The yarn engaging device includes a pivot housing and a movably hinged yarn lifter head and is seated on a pivot and bearing shaft in a partially rotatable and axially displaceable disposition. A yarn catcher plate, clamping shears, and a yarn guide plate are disposed on the yarn lifter head. The yarn engaging device also includes a stop element for engaging the housing of a respective winding station for stopping movement of the yarn engaging device at a first predefined position with respect to the winding station housing. The travel limiting device includes a clamp assembly that is clampable to the yarn engaging device when at the first predefined position and guide rails attached to the doffer upon which the clamp assembly is slidably disposed. A pneumatic cylinder selectively causes the clamp assembly to clamp onto a braking tube that is part of the yarn engaging device. Another stop element disposed on the doffer limits travel of the clamp assembly and the clamped yarn engaging device at a second predefined position whereat a yarn supply is positioned against an empty tube. Thus, it possible to repeatedly place a yarn end of a supply yarn against an empty tube held in the winding frame at a precise and accurate position without elaborate adjusting steps being required at the winding station or on the doffer.