Using Hydraulic Systems for precise postioning
Using Hydraulic Systems for precise postioning
(OP)
Hi All,
First time poster, long time lurker.
I have an application where I need to have a high force generating motion control system, and after a bit of research I've landed on using hydraulics for the application. I've had some design experience with fluid power, albeit mostly in a university setting classroom/lab.
The application is moving a platen up to a fixed plate for a pressing application. The fixed plate will have a load cell which is used as feedback for whether more force needs to be applied, or less. I need to generate around 24,000 pounds of force, with positional control of at least .005" or better over a 8" stroke. I looked at using a hydraulic cylinder, but the size required would be greater than a 4" bore. This lead me to look at hydraulic motors. It looks as though I could attach the motor to a leadscrew, and the leadscrew would be connected to the platen. Ok, so now I potentially have a hydraulic power source selected....
Now onto the control of the hydraulic motor, this is where I am in unfamiliar territory. I've seen that electro-hydraulic servo valves can be used in conjunction with a feedback mechanism (LVDT, MDT/LDT) and a motion controller. Is it really this simple to get high accuracy for my application? Am I overlooking a less complex alternative?
Thanks in advance!
EDIT: I should add that after the pressing of the part occurs, the platen needs to return to it's original position within .005" or better.
EDIT #2: I'm seeing that a leadscrew is not a very suitable choice as the life span would be very short. Assuming this, a hydraulic cylinder may be a better choice. Are my positioning requirements feasible with motion control of a hydraulic cylinder?
First time poster, long time lurker.
I have an application where I need to have a high force generating motion control system, and after a bit of research I've landed on using hydraulics for the application. I've had some design experience with fluid power, albeit mostly in a university setting classroom/lab.
The application is moving a platen up to a fixed plate for a pressing application. The fixed plate will have a load cell which is used as feedback for whether more force needs to be applied, or less. I need to generate around 24,000 pounds of force, with positional control of at least .005" or better over a 8" stroke. I looked at using a hydraulic cylinder, but the size required would be greater than a 4" bore. This lead me to look at hydraulic motors. It looks as though I could attach the motor to a leadscrew, and the leadscrew would be connected to the platen. Ok, so now I potentially have a hydraulic power source selected....
Now onto the control of the hydraulic motor, this is where I am in unfamiliar territory. I've seen that electro-hydraulic servo valves can be used in conjunction with a feedback mechanism (LVDT, MDT/LDT) and a motion controller. Is it really this simple to get high accuracy for my application? Am I overlooking a less complex alternative?
Thanks in advance!
EDIT: I should add that after the pressing of the part occurs, the platen needs to return to it's original position within .005" or better.
EDIT #2: I'm seeing that a leadscrew is not a very suitable choice as the life span would be very short. Assuming this, a hydraulic cylinder may be a better choice. Are my positioning requirements feasible with motion control of a hydraulic cylinder?





RE: Using Hydraulic Systems for precise postioning
On the other hand, I have used linear actuators for this purpose.
I just did a quick search and the first hit I got seems like it might be suitable for your application.
Here is the link: http://www.edriveactuators.com/catalogs/eliminator...
From a quick skim over the catalog, it looks like you can get a force of 25,000 lbs from a "stock" unit.
Stock accuracy is .002 in/ft with an option for .0005 in/ft.
Stock backlash is .003 with zero backlash an option.
Repeatable position accuracy is .0005
The B10 life at 24,000 lbs looks like 8 million inches
Hope this helps ..... Mike
RE: Using Hydraulic Systems for precise postioning
Thanks for the input!
RE: Using Hydraulic Systems for precise postioning
Do a search for my company and add the word press. You will see we have lots of experience in pressure force control. This application should be easy.
Peter Nachtwey
Delta Computer Systems
http://www.deltamotion.com
RE: Using Hydraulic Systems for precise postioning
RE: Using Hydraulic Systems for precise postioning
zipfactor should tell use what his application is. I/we have lots of experience in many different industries with position/force control or limit.
One thing the OP should be aware of is that one can control force or control position but both can't be controlled at the same time. However, one can limit position or force at the same time.
Peter Nachtwey
Delta Computer Systems
http://www.deltamotion.com
RE: Using Hydraulic Systems for precise postioning
The application is pressing composite layers together for an automotive company. I would say that position control is the priority for the hydraulic system, and force could be managed by the load cell. Does this arrangement sound feasible?
Thanks again!
RE: Using Hydraulic Systems for precise postioning
RE: Using Hydraulic Systems for precise postioning
The hydraulic system and controller can probably be bought for 10K. The programming and installation would probably cost more unless you are going to do it.
Your system seems feasible but why not tell us what you are trying to do. We have been in business controlling hydraulic systems for decades and about 100K axes of control. There is little we haven't seen before.
Peter Nachtwey
Delta Computer Systems
http://www.deltamotion.com
RE: Using Hydraulic Systems for precise postioning
If you know your cylinder sizes and the required force and speeds you can work back from these to calculate your power requirements. Rule of thumb I allow ~ $1000/Kw to build the required power unit on a one off installation.