automatic torque wrench

[BenPLC 0]

I'm trying to introduce automatic torque systems into the plant I'm working at: One of our processes in production assembly is torquing a male threaded fitting into a female fitting at a customer specified torque value(39Nm). We are currently screwing the male fitting into the female fitting by hand as much as possible --15 hand turns (approx.) Then, we use a torque wrench to finish it to spec. The goal for the new system, is to srew the parts together and torque them all in one step. I'm sure there is something on the market already, but . . .what I'd like to do is: Using a DC driver 18V or 24V, drive the nut onto the male fitting (via socket) When the driver stops or 'bottoms out', I'd like to translate the current spike (?mA) into a readable form in the PLC. After this value (assuming I succesfully translated the analog signal into a digital signal) is sustained for a given time period (? seconds), I'd like to send a PLC output (green lamp turns ON, and holding fixture unlocks) I'm using the FX series PLC brick unit. I am new at the analog signal processing. So, the analog factor will be my biggest obstacle. Does anyone know how this could be done? I'd be grateful for any advice during my attempt at this thanks -Ben

[panic mode 246]

don't mean to throw you off but did you consider ready made nutrunners? there are plenty to choose from and you get no headacke about prooving and approving it. all you need is interface with plc and that is few digital I/O. http://www.atlascopco.com/tools

[bob1371 0]

We use a couple different nutrunners. Stanley http://www.stanleyassembly.com/products/Th...Nutrunners.aspx GSE Tech-Motive http://www.gsetechmotive.com/ All of these but one stanley we use the controller and just send discrete signals to/from PLC. On the one stanley we have the analog signal from the transducer going to analog plc card. Price wise this is a good choice. Bob

[hungvu 0]

We use a small proximity switch at the end of a torque screwdriver. During the screw-in time, the proximity switch use to count how many revolution the screw has turned (for set the minimum revolution required...). When the torque has reached, the screwdriver still running but the proximity switch is stop pulsing signal, this is the time to set the torque is OK signal. Y0 = turn the "Torque Screwdiver" X0 = proximity switch X0 on THEN counter C0 K20 IF Y0 on AND X0 stop COUNT (do not change STATE in 0.5 second) THEN output TORQUE OK and RESET C0