Twist tying machine

Abstract

A ring encircles produce placed on a work table. Tie ribbon is fed by pressure rollers around the inner periphery of the ring to form a complete loop. A first gripper clamps and retains the free end of the ribbon against a second gripper. The pressure rollers operate in reverse retracting excess ribbon about the produce. A friction clutch, operative only for reverse ribbon feeding, allows for ribbon slippage as the ribbon tightens around the produce. Then the second gripper clamps the other end of the ribbon against a twister head and a twister mechanism rotates the clamped ends of the ribbon about a common axis twisting the ribbon ends together. Shearing edges sever the engaged ribbon from a ribbon supply during twisting. The grippers and twister mechanism are at ends of the concentric support rods and tubes, and the grippers in clamping move along the rotational axis of the twister mechanism. Axial gripper motion is provided by cylinder valves having pistons concentric with and supported by the gripper support rod or tube and acting, respectively at the ends of the gripper supports away from the tie ribbon. Rack and pinion mechanisms provide rotation of the twister mechanism and forward and reverse feeding of the ribbon. All components are pneumatically driven. The design accommodates normal wear and temperature variations without adjustment.