Control system for can coating

摘要

A can coating machine control system includes a coating control signal that functions as a go/no-go signal based on a plurality of monitored conditions such as can in position, vacuum pressure, gun in position, guard in position and speed condition. Local pressure regulation of the coating material in the spray gun is provided along with optional control of the material temperature. Local pressure regulation allows for optional spray weight control based on a wrap number derived from speed and gun spray durations. A CAN to CAN network buffer is provided as well for primary network isolation. A gun control circuit may be used to select specific gun drive signals and to adjust gun drive signals based on real-time feedback of the actual spray duration.

主权项

1. A method for controlling an actual spray duration time of a coating gun that sprays coating material onto a surface of a container during a coating operation, comprising the steps of:
detecting rotational speed of the container to determine the number of revolutions of the a can during a time period, generating a trigger signal to the coating gun during the coating operation based on said detected rotational speed, said trigger signal having a trigger signal duration to turn the coating gun on to spray coating material from the coating gun onto the surface of a container and to turn the gun off to terminate the spraying of coating material from the coating gun; detecting changes in the pressure of the coating material supplied to the coating gun during the coating operation; generating a pressure signal that is a function of said detected pressure changes detected during the coating operation; determining an actual spray duration based on said detected pressure changes during the coating operation; comparing said actual spray duration with said trigger signal duration and if said actual spray duration is longer than said trigger signal duration then decreasing said trigger signal duration of a subsequent coating operation, and if said actual spray duration is shorter than said trigger signal duration then increasing said trigger signal duration of a subsequent coating operation.