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Target Design Conciliation & Application Review

If we could eliminate the gearhead and the bellows coupling a large step would be taken in reducing the cost of the machine. If we could decrease the backlash, increase the stiffness, and improve the inertia matches we would end up with a good relationship between load and motor reaction, and allow us to increase the gains of our controller of for better overall performance of the machine.

Design Implementation

To meet the challenge outlined above the Danaher Cartridge Direct Drive Rotary (CDDR) motor was chosen. Among the many benefits of the CDDR is zero backlash, and a very stiff mechanical connection to the load, thus eliminating problems associated with couplings and gearboxes. Since the CDDR motor is directly connected to the machine inertial matching is not required as it is on a conventional rotary motor. With direct drive, inertia miss matches of 250 to 1 is common, and miss matches of 800 to 1 have been implemented.

Overall Success

The CDDR enabled the manufacturer to achieve the following:

The direct connection to the anvil cylinder will eliminate backlash and torsion between the two. This gives you in practical terms a high inertia motor driving a lower inertia knife cylinder. They expect to at least quadruple their gain settings in their controller.

Assembly of the machine will be easier with fewer parts

The noise being generated by the gearbox will be gone, quieting down the machine

Cost reduction: one CDDR against a servo, gearbox and couplingClick here for link to motor sizing software tool used to develop this application

Application Profile

Industry – In line and Offline Finishing Equipment for the Graphic arts industry.

Machine Type – Rotary cutter for a digital printing machine.

Application Challenge – Lower the cost and maximize the performance of an existing product line. The existing machine had a base with a servo driven anvil cylinder on which different knife cylinder units can be mounted. Every knife cylinder had a fixed cutoff size and is gear driven from the anvil cylinder. Because of cost the knife cylinder is not servo driven.