Drum

Commands | Description | NVS Parameters | Procedures | Theory of Operation

Commands

drum

Description

Holds the plate during imaging. Made of cast Almag 35 Aluminum.

Diameter 286.3mm (+ or - 0.1mm)
Length: 47" at full diameter
Rotating speed 0-166 rpm (up to and including S66)

Note: The drum, encoder disk, and frame are carefully matched and measured for mechanical accuracy. These measurements are part of the geometric correction values used by the recorder to ensure image accuracy and repeatability. Any adjustments made to the mechanical alignment of the drum mounting or encoder disk mounting requires a full geometric accuracy test and recalibration. Avoid changes to the mechanical setup of the drum, if possible. Change the mechanical setup only after consulting Creo engineering personnel.

NVS Parameters

drum module

Procedures

Adjusting the drum drive motor belt tension
Replacing the drum drive motor belt
Cleaning the drum and carriage drive pulley
Cleaning the drum

Theory of Operation

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 four different sets of PID coefficients for the servo:

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 slowly against possible mechanical resistance, e.g., when loading a plate.

Hall mode
Used to run the drum from tach pulses from the Hall effect switches in the drum motor without getting feedback from the tach encoder.

See also Main drum drive amplifer.