GregV (Customer) asked a question.
I have a VFFS continuous motion packaging machine I’ve been upgrading. I am using the Pac 3000 and Sure Servo amps and motors. There are three servos drives, two for the film pull belts (right and left) and one for the jaws. At the moment all the drives are driven by a 0-10V signal. One belt servo and the Jaw servo feedback to a HSI module. The Jaw is scalded to 10 pulses per degree of travel. (360 degrees total). The pull belt is scaled to 3090 pulses per inch of film. The Jaws are closed for 116 degrees and the film travels 4 inches through that part of the process.
I’m having issues synchronizing the film through the jaws.
My question is would it be better to have the pull belts driven off a HSO module that ties into the HSI form the jaws?
Is there a better way of setting this up?
Thanks in advance!
I sent this to our Productivity development team to see if they may have a recommendation for you. I will update this thread once I hear back from them.
First, as we know, there is not a true electronic gear nor mapped profile function currently in the Productivity Series controllers. We know and are aware that these are very important functions to have in a controller for true axis synchronization.
I do not have a direct answer to your question and I can’t think of an easy solution but instead will lay out some of the things I would try to get synchronized motion from a controller that doesn’t have native synchronization capability.
Synchronized speed of the film and jaw through the crimping and cutting stage ( aka the 116 degree period ) and Continuous Error Adjustment to keep the film in register with the jaw are likely 2 critical components to make this run successfully.
SureServo Encoder Output to Control Jaw Position/Velocity
I would look at the possibility of using the encoder out of one of the SureServo film drives (assuming that both film drives run the same speed) to control the speed of the jaw. What this will do is give a solid, linear relationship of the two axes: this is true synchronization. Review parameters P1-44, P-145, P2-160, 161, and 162 in the SureServo manual. If I understand it right, the crimping portion (116 degrees) would be 116*10 = 1160 pulses for the jaw while the film is 4*3090=12,360 pulses. The rest of the cycle travel may have to run at a different relationship based on product length but the same idea where 244 deg * 10 = 2440 pulses and product length of the bag in inches * 3090. There are 4 numerator settings that can be set to these two ratios so they can be selected on the fly via an input signal on the SureServo.
Since you have these axis tied to an HSI, use the PLS instruction tied to an HSI output to control the input mentioned above as to when to run the crimping portion and when to run the return to start portion of the move. Reset the HSI position each cycle (to prevent drift ) by using an input on the HSI and perhaps a sensor on the jaw or something similar. Review the HSI help file to see how to do reset the position on the fly.
You can also use the REG instruction to help determine error by getting registration events for the JAW and the film registration mark (with relation to the jaw position).
I hope this helps