Helical flexure used in self-aligning, long-life die cutter

Abssac has utilised its helical flexure technology in a die punch design to enable a manufacturer of cellophane packaging machines to eliminate the need for in-service adjustments and to extend die life when used on high-volume production runs.

In the original design the die cutter was attached to a solid shaft holder, which had to be adjusted continually to keep the cutting edge perpendicular to the roller. The machine operated 24 hours a day, at the rate of 180 packages per minute. Under these conditions, the normal life obtained from the die cutter was one month, after which it had to be replaced.

The performance capability of a helical flexure is determined by six major characteristics: flexure outside diameter, inside diameter, coil thickness, material, number of coils, and number of starts. By altering these characteristics, torque capacity, angular and parallel misalignment capabilities, torsional and lateral bending rates of flexured u-joints can be modified to suit specific application requirements.

For the die cutter project, Abssac undertook a short design study and concluded that using a shaft manufactured from 17-4pH (a heat-treated stainless steel) and the correct flexure design would ensure load and cutting edge perpendicularity. The end result was, in effect, a shock-absorbing yet load-bearing assembly that extended the die cutter life from one month to 10-12 months.

Chris Cattle, technical sales manager at Abssac, states, "The flexure product is quite unique and allows the design engineer to amalgamate multiple designs into a single-piece design. It is one of the few products that really does allow the engineer to dream."

Follow the link for more information about specialist helical flexures.