MES in vehicle manufacturing - Torque Error Proofing

In vehicle assembly and engine assembly, bolts are used quite a lot to attach 2 parts together.

This article will use an example of engine assembly, to introduce how bolt torque operations are integrated into Error Proofing system.

Before torque operations happen, there’re lots of work need to be done as pre-conditions:

1)       Quality department calibrate torque value of each torque gun.

2)       Process engineers configure torque parameters, such as: station, torque gun number, click number, torque angle, program code.

Torque operation system consists of: torque gun, torque controller, PLC, torque server. Torque gun is the executor; controller is the logic controller of torque gun, and it’s also communication layer between torque gun and PLC; PLC transfers control command and program code; torque server is used to store historical torque values, and can also generate torque curve for analysis.

Diagram 2.9-1 shows key process of a typical torque error proofing:

1)       Engine identification: when engine comes to torque station, PLC reads engine serial number from RFID Tag, and sends it to MES via OPC.

2)       Error proofing request: MES queries torque process of this type of the engine, and get related data such as torque gun number, click number, torque angle, program code, and then send these data to PLC via OPC. Then PLC send torque command to torque controller.

3)       Error proofing result: worker will execute torque operations based on working instruction, robot will work based on torque command; while one click of a gun is validated, then controller will regard it as a valid click, and update it to PLC; while a gun reached its requested click number, then PLC will regard error proofing of this gun is passed; when all guns passed error proofing, then PLC will regard the error proofing of this engine in this station is successful.

4)       Torque data record: torque controller will upload all torque process data to torque server, which can generate torque curve for analysis. And controller will also send the final torque result and torque values to MES via PLC and OPC, the data will be linked to engine number, as part of traceability.

Diagram2.9-1: torque error proofing

 

This article introduced one method of torque error proofing, there’s another method which is also quite often used: to configure click number and angle as torque profile inside torque controller, so MES only needs to configure and transfer torque profile to controller via PLC.