Servo Driven Folding machine.

[Carples 0]

Ok guys not sure this belongs on this forum but if a PLC was to go on machine it would be a mitsubishi. I recieved a second hand folding machine from one of our USA plants, it is a much better unit than the one we currently use, but it was an incompleted project that as far as I know does not work but was close to completion. Firstly how the Folder Works. The folding machine is feed a continous piece of paper "the Web", generaly 4000-6000m long. This web is printed with an image that repeats every 350mm "the Repeat", it is also perferated at preset spacing i.e. lines of holes across the web, and slit along the length i.e. line of holes along the web. The Folding machine has some rotating spirals, cams and a moving guide shute, all thes parts are mechaicaly linked. On my current unit they are driven by a vairable gear box from line shaft. The fold sequence As the paper is feed into the machine the guide shute recipricates its speed and amplitude is governed by the size of the fold length As the shute changes direction it causes a bend in the web and it buldes in the original direction of travel The cam comes around and squashes the buldge forcing the perferations to buckel (provided its in the right place) The sprial leading edge passes over the fold and captures it giving a base for the next buldge to form on generaly there are 4-5 captured folds before the web drops out of the machin in folded form Streached out a bit and layed on its side it would look like this /\/\/\/\/\/\/\/\/\/\/\ OK so my new machine has a servo drive rather than a variable speed gear box. This on its own is an easy enough system, work out the speed ration from paper drive rollers to folding speed, feed this into servo amplifier, and off you go. But.. The print and perforations can move, or tension in the web changes, this causes a change in the relarive positions of the repeat to the machine. The Registration system - PC104 black box (please oh please don't screw up) type affair. This system tracks the web and machine position and adjusts the machine accordingly to match the paper. This system uses a TDC sensor for the repeat position of the machine (Printing machine, Perferator, or Folder), a 7 segment mark on the paper, and an encoder, to determine the position, then generates a pulse output desgined to drive a stepper motor to correct any discrepency.(.0005 inch increments) Now to my question What is the best way to control the servo given that it must track the machine speed with a given ratio (electronic gear box) and make minute changes to its position ???? I think the native functions in the servo amp will not be flexible enough. Was thinking a FX positioning module but I have not used them before. Can I -- - Take the Encoder Pulse train from the drive rollers into the positioning module scale it to suit my fold length then output it to amp - Half or double the output frequency for say 6 pulses then drop back to scaled value to make my registration correction steps - Do it all really fast - machine speed 150m/min expected accuracy 0.1mm (5-10 corrections a sec) Well this post has grow out of control, hopefuly it makes sense Edited 16 Apr 2008 by Carples

[panic mode 246]

if i understand correctly questions are if the servo can perform in this application. servos can move fast but don't expect miracles. to properly answer this you need to get pencil and paper out (or equivalent) and get some things straight (such as servo axis feedback resolution, user unit setup in the drive, motor rated speed, move distance, move time, load and load inertia for example).

[Peter Nachtwey 15]

I understand. A picture of the cam motion profile would be handy but you probably haven't got that far yet.. Edited 17 Apr 2008 by Peter Nachtwey