Drum

See also Commands | NVS Parameters | Parts | Procedures | Troubleshooting

Description | Theory of Operation

Description

The drum holds the plate during imaging.

Diameter:

• 5080 engine: 432 mm (17")
• 5880 engine: 496 mm (19.5")

Length between flanges: 2122 mm (83.5")

Weight:

• 5080 engine: 380 lb
• 5880 engine: 445 lb

The main components are:

• Drum tube and two end bells.
  Each piece is cast Almag 35 Aluminum.
• Drum drive assembly (includes drum motor and timing belt)

Theory of operation

Servo loop

The servo loop controls the drum speed. The encoder senses the position and speed and sends the signals to the digital controller on the MPE. The output from the controller is sent out to the MDA which converts the requested drive information into drive current for the motor. The programmed speed and the PID coefficients are stored in the DRUM NVS module.

There are five different sets of PID coefficients for the servo:

• Run mode
  Used during plotting.
• Velocity mode
  Used to lock the drum to a set speed during a spin command.
• Position mode
  Used to hold the drum in a given position.
• Soft mode
  Used to hold the drum lightly when the drum is moving the drum slowly against possible mechanical resistance, e.g., when loading a plate).
• Hall mode
  Used when using feedback from the Hall effect switches in the motor.