| 摘要 |
A stacker having platforms movable along a path by chains. Cam followers on the platforms engage a cam surface which controls the platform path. The chains are driven by a motor in a closed-loop system which monitors the platforms and controls their speed. The closed-loop system first decelerates the platforms and thereafter stops one platform in the intercept-ready position. The platform cam follower enters a claw which moves the end of the platform through the stream to collect signatures when the downstream platform reaches a predetermined count and deposits the stack on a turntable. A piston assembly rotates the turntable one-half turn after each deposit. Different pressure values are selectively applied to the piston assembly to slow the turntable before it is halted. A rotatable motor coaxial with the turntable axis drives the pushers through drive chains maintained under tension by gas springs which impose opposing forces upon these chains to maintain chain tension regardless of the direction the chains are driven. Jets on the surface of the turntable selectively emit air when a signature is deposited thereon to facilitate removal of a batch. A microprocessor-based controller continuously monitors and periodically adjusts the drop delay and stacking speed of the chains and the stacking platforms to allow the platforms to collect signatures at the lowest speed commensurate with stack size, to form neat stacks, the latter operation being accomplished by either a table look-up or an on-line calculation technique.
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