Stacking method and apparatus

Abstract

A self-adaptive stacker comprising infeed and stacking sections whose movement is coordinated to provide interception of the signature stream. A microprocessor utilizes a signal, representative of the infeed conveyor speed, together with a signal from a signature counter, to track the movement of each signature and thereby its arrival at the intercept position. Low armature inertia motors drive the three axes, (stacking section, the turntable, and the ejectors) to provide rapid starting, acceleration, deceleration, and stopping at selected positions. These motors are controlled to interact in real-time in order to adapt the three axes to the rate of the incoming signatures. The movement of the signature carriers is altered, when necessary, due to speed changes of the signature stream. A sensor located at the intercept ready position detects the passage of a signature carrier to initiate acceleration of the signature carrier by an amount which is a function principally of signature thickness, velocity, and separation distance to control the amount of acceleration required to move the carrier beneath the first signature of the next stack to be formed. A turntable section forms compensated bundles by rotating a platform. A pusher assembly is mounted beneath the rotatable turntable platform and includes pusher bars arranged by linkage members to move precisely along the path of the drive chain to enhance monitoring, control and movement of the push rods. A sensor senses the passage of a push rod to detect the initial movement and subsequent thereto the arrival of a push rod to the home position.