Thermal Spray Control System

Transcription

1 Thermal Spray Control System By Anila Jahangiri, Project Scientist V I Engineering, Inc. Richard Allor, Research Engineer Ford Motor Company Category: Automotive National Instruments Products Used: BridgeVIEW 2.1 PCI-MIO-16XE-10 DAQ Board SCXI Slot Chassis SCXI Channel Isolated Analog Input (2) SCXI 1328 Iso-thermal terminal block (2) The existing system: Ford Motor company was using a Mitsubishi PLC based system which controlled and monitored various parameters of four mounted arc-spray guns on a 6-axis ABB robot. This system also controlled the movement of the robot through a robot controller and the movement of the turntable used for fabrication of metal forming dies. The operator would use a touch terminal type interface to enter the desired values for the various gun parameters, subroutine type for the robot-controller and turn table direction/speed. At the end of the desired time limit for that process, if another spray-process was desired the operator would have to enter another set of configuration parameters through the touch terminal. The thermal spray process at Ford is usually a chain of steps with the parameter s value changing from step to step. Such type of a process required the presence of an operator to be on site during the complete spray process and continually updating the touch terminal with new parameter values at the end of each event. For processes lasting for a number of hours and consisting of a number of events, this process could be very cumbersome. The challenge: Ford Motor Company desired an automated Human Machine Interface (HMI)/Supervisory Control & Data Automation applications (SCADA) based system where an operator could execute a pre-defined set of timed events (a schedule) through the PLC. The HMI/SCADA

2 application would replace the touch terminal interface through a scheduled editor. The schedule would determine when to turn ON or OFF a particular gun. It would also set the desired amperage, voltage, gas type and gas pressure for all four guns. The schedule would regulate what direction the turntable might have or what subroutine to execute through the robot controller. During the execution of a schedule, the operator would have the ability to change the parameters to a value other than what it was originally set to. The system would also monitor, record and plot temperatures from infra red sensors sensing surface temperatures of spray deposits. These temperatures along with the gun parameters would be recorded to file for later analysis. The system would also have the capability to monitor errors communicated from the PLC to the PC. During an error situation the operator would have the capability to acknowledge and clear errors without stopping the spray process. The Solution: Using National Instruments BridgeVIEW software with the OPC lookout Driver and a standard PLC programming cable connected between the PC s serial port and the PLC s CPU port, VIE has created a fully automated Thermal Spray Control System. This system can be used to create and then execute a sequence of spray events through the PLC. Using the National Instruments PCI DAQ board and SCXI modules, this system can also acquire temperatures from IR sensors and/or thermocouples. Introduction: Ford Motor Company is a leading automotive company based in Dearborn, Michigan who contracted V I Engineering Inc, a Premier National Instruments Alliance Member, to develop an automated PLC-based system for thermal spray control. The system is used to control and monitor various parameters of arc spray guns and the movements of the robot on which they are mounted. The system further monitors temperatures from the surfaces of the manufactured tools. Thermal Spray Control System: Figure 1 is a picture of the Spray Forming Chamber that is used for manufacturing tools. Figure 2 shows the main screen for the Thermal Spray Control System. Clicking on the Edit Schedule button on the main screen will take the operator to the Schedule Editor screen (Figure 3). A schedule is composed of 17 columns for timing and gun information and added information for turntable direction, turntable speed and robot subroutine. The operator may enter values for the desired gun amperage, voltage, gas pressure and gas type for various steps and save this information to an ASCII-based schedule file. After creating a schedule, the operator may then exit to the main screen and run the schedule. The run cycle is composed of loading data from consecutive steps in the schedule into the controls for the gun parameters. Each step runs for the time duration of that step. In between two step changes, the control values for the gun parameters and the gun ON/OFF controls are operator selectable. During a run cycle, a gun will be turned OFF if either of the voltage,

3 amperage or pressure for that step for a gun is zero or if the gas type is None. At the end of a schedule, the guns will be turned OFF and the robot moved back to it stationary position. The operator is informed that the schedule has been completed. During a run cycle, if there is ever an alarm condition, the operator will be notified. The operator may go to an acknowledge error screen (not shown) and acknowledge and clear the errors. By going to the view plot screen (Figure 4), an operator may view the amperage, voltage and pressure for the four guns or he/she may view the IR sensor temperatures. Summary: Using National Instruments BridgeVIEW software, VI Engineering has designed an automated manner to run the thermal spray process with minimal operator intervention. The operator may create and execute a process schedule of any complexity level without the need to be at the site during the process. In addition, the system provides the operator with easy to use alarm monitoring/error acknowledging/data monitoring interfaces and the ability to save data for possible future analysis. One of the future additions to the new Thermal Spray Control System will be a closed loop control of the guns amperage based upon the temperatures measured from the IR sensors. Considering the fact that BridgeVIEW uses the powerful graphical programming language G, VI Engineering will be able to add the closed-loop control functionality to the system at minimal cost to the client.

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