Tuning a Van Dorn

[jnewmanco1]

Are there any Van Dorn HT Series experts out there that could give me a brief, or lengthy, explanation of the tuning functions on one of these machines. I think a lot of my problems could be solved if these things were just tuned properly. Alas there is nobody here anymore that knows how to do it. I would be more than happy to learn, especially if it made my life easier.

What exactly is it that I am tuning anyway? An hydraulic valve or something that controls the valve? What is Gain, Rate, and Reset and how does that affect my machine's performance? How do I properly set these parameters so that the machine actually does what I am asking it to do instead of bouncing around like crazy trying to do what I ask it to do when it simply cannot do it based on these settings being screwed with one too many times? I know these are very popular and widely used machines so surely someone out there can give me some advice or instruction.

I would so very much appreciate anyone's help in this area.
Thank you.
James

[ArikB]

lol good luck. I asked a Van Dorn rep that same question and didnt get much in the way of intelligible answers.

We lock in our processes which kindve limits the amount of processing our technicians are allowed to do unnoticed. Our operators audit the process every 4 hours and position changes to shot size or xfer are immediately picked up. Being the crafty crew that process techs tend to be, some of our guys have started using those three mystery settings to get away with changes they probably shouldn't have.

The fact that changing them affects the outputs means that they have some function but, honestly I've never heard a good answer as to what that may be.

I'm still hoping I catch that engineer that decided that a rigid hyd line running right in front of the ejector plate bolt holes would be a great design. It's not bad when your ejector pattern is side to side but top and bottom will frustrate the most patient of people.

[jnewmanco1]

Well thanks for responding Arik, even though it was not particularly what I was hoping to hear. I'm told that these settings are very important as far as valve response goes but cannot find anyone that knows how to properly set them. I definitely see differences in the way the machine reacts when changing these numbers but there must be a scientific way of utilizing these settings to get the best performance without just punching in numbers and hoping you happen to land on something that sort of looks right.

I also thought these were very widely used machines and that there would be a ton of experienced users on the forum that could answer what I was sure was a simple question. I guess maybe most people have moved on to newer and better equipment. I wish we could. Anyway, thanks again. I guess I will try the Van Dorn rep and see if he can give me an intelligible response.

[Airwinghma]

Ok jnewmanco1, here we go.
Servo valves and servo-proportional valves are operated by transforming a changing analogue or digital input signal into a smooth set of movements in a hydraulic cylinder. They are electrically operated valves that control how hydraulic fluid is ported to an actuator. An electric command signal (flow rate set point) is applied to the integrated position controller which drives the pilot stage. The thereby deflected nozzle flapper system produces a pressure difference across the drive areas of the spool and effects its movement. The position transducer (LVDT) which is excited via an oscillator measures the position of the spool (actual value, position voltage). This signal is then demodulated and fed back to the controller where it is compared with the command signal. The controller drives the pilot stage until the error between command signal and feedback signal will be zero. Thus the position of the spool is proportional to the electric command signal.

Basically a valve is tuned to react to the voltage or milliamps applied to it, the valve shifts per the amount applied and allows a specific volume/pressure out. On your Van Dorn HT go to the user calibration #1 screen and on the top left side is your valve settings. The valves are as follows: 0 (CN) is for the clamp, 1 (XH) is for the injection unit and 4 (G) is for the system. The span voltage is for your max pressure setting, zero volts is your min setting, the ramp time changes how the valve reacts to changes between stages. The Van Dorn Manual has specifics on how to calibrate them in section 9, machine set-up procedure.


Hope this helps if you are still looking for answers

Scott