The engineering team from a local articulated truck manufacturer has recently made the decision to upgrade and automate an existing paint booth that is used to a paint the rear axle bearing components, with the aim of significantly improving the process.
The senior management team from your organisation have been succesfull in winning the contract to design and install a PLC control system for the paint booth and you have been tasked with that part of the project, the process will require the use of temperature sensors and heating elements to ensure that the parts are cured at the right temperature.
The management team are also still in the process of producing a proposal for futher upgrades to the customers existing process. The management team have asked that you produce a proposal that will provide an evaulation of the potential for upgrades to a customers machine and the benefits to the organisation.
Task 1 – System Control, (LO4)
The system shown below in figures 1 and 2 is to be controlled by the PLC. The PLC will perform the following functions, if and only if the ready signal is received from the microcontroller. You are required to design and write a program for the paint booth process.
Rules of Operation
Step 1 – Upon activation of the system ready push Button, the system will be ready to use – only if the conveyor, extraction and ovens are switched off. This will be also be indicated by a the red “System ready” light. The system must have an emergency stop to shut down the full system.
Note: Emergency stop should stop the full system from working until reset.
Step 2 – When the “system ready” light is on, the extraction fans are activated using a push button located on the control panel. The extraction fans must be running constantly and must remain running for a minimum of 5 minutes after the paint booth is switched off in order to remove paint fumes.
Step 3 – After the extraction fans have been running for 5 minutes, the oven heating elements will be automatically switched on.
Step 4 – The conveyor will only start when all of the above conditions have been met, a part is detected by proxy sensor 1 and the heating elements have been on for 5 minutes. The conveyor will only stop after a 5-minute delay allowing parts to be cleared from the conveyor belt.
Step 5 – The Stop button on the control panel will turn off the full system after a 5-second cycle down delay. In order to reduce inventory, the paint booth should automatically cycle down once a pre-determined number off parts have been completed.
Step 6 – All outputs must have a corresponding indicator light on the control panel that is used to inform the operator what is running.
Step 7 – All parts must be counted in and out of the paint booth.
PLC Design Notes (20 Marks)
Your company has been asked to submit a comprehensive a set of design notes for the PLC program based on the required functionality described above. This is part of the tender process and will help the engineering team at the articulated truck company make the decision on which OEM to award the contract to. This should include:
• Any presumptions you have had to make
• Flowchart or Sequential Function Chart
• I/O list
• Variable list
• System Block diagrams and Electrical connection diagrams