PLC for press brake

[DynMetalworks]

I have a old press brake that I want to retrofit a PLC to with a linear encoder on the Y axis and a stepper motor on X axis.

Y Axis: I would have a home switch at the top of the travel that I could jog the ram up to then zero the encoder on the PLC. I could then enter in the PLC at what distance I want it to output a signal to activate a solenoid to change the hydraulics from fast to slow. Then another distance that it sends a signal to active a solenoid to stop the ram movement.

X Axis: I enter in a dimension and it moves the stepper motor to that distance. This part seems pretty easy once I know my steps and lead screw ratio.

I'm not sure what PLC would work for this? I've attached a picture from a manufacture who has a PLC on their shop press brake that controls the Y axis. This is exactly what I'm wanting with the addition of the X axis.

 

[JeffKiper]

Just about any PLC can do this. Its all about time vs money. You can get an AB or Automation Direct. What HMI are you going to use? How much programming experience do you have?

Im not yrying to be the negative one just asking some basic questions so we can gauge where to send you for more information. Have you thought about having an integrator doing it for you?

 

[DynMetalworks]

Jeff,

Thanks for the reply. I have quite a bit of experience with cnc plasma controllers. I've worked with Mach3/4, Ethernet smooth steppers, and clearpath servos. My experience with this make the X axis (back gauge) part pretty easy.

I have no experience with PLC's, programming them, or linear encoders (I have installed linear scale DROs). I had wanted to get a PLC with a built in HMI.

 

[JeffKiper]

I have never seen and mach # cnc on a press brake. You can program multiple moves into the PLC. With that bwing said its a steep learning curve with anyone to help mentor you. You have to write the code from scratch.

Are you wanting to replace the existing controls on the press brake or just add these to it?

I'm personally against using a PLC HMI combo. If 1 unit fails you have to replace all of it. If an i put card fails you just replace that card and not the entire PLC.

 

[cardosocea]

Don't forget the cost of the software to program the PLC. That's what's going to make a difference in which way you're going to go.

For the encoder, do use an appropriate input card to count steps.

In your logic, I wouldn't zero the step count every time the top switch is made either. I'd have the zeroing/homing function programmed for an engineer/administrator to operate. Additionally, you can place two position switches at the extremities and knowing the distance between them, calculate your pulses per inch figure.

The reason I wouldn't reset the encoder counts every time is that it will mask encoder issues. I'd instead have an alarm raised if the counts whenever that switch is made are outside a certain interval (say 5 each way), this tells you something's been slipping and your position may not be as good as you think it is.

 

[Liam Moran]

I am currently doing exactly this on an old Haco machine I have in my workshop. The linear encoders I am using are OPCON model MPS. These are specifically designed for Press Brake Y axis control.

 

[Liam Moran]

My machine has 2 cylinders on the Y axis, with proportional control on each side. I am using a Siemens S7 1200 PLC which will take the control signals for Y1 and Y2 from 2 of the MPS units above. The Hydraulic valves are Hoerbiger proportional units, 1 for each Y1 and Y2, which are driven by WEST PAM-199-P amplifiers, driven by -10v to +10v analog outputs.
The interface is a HMI from Weintek MT8071iE. I will have a system for recipies for different material thicknesses and bend angles, with control of the X axis for multi bend control.

 

[DynMetalworks]

I appreciate the replies. I do want to replace the current controls. I want to keep the new system very basic/simple. This shop press has a PLC for the cylinder stroke http://www.edwardsironworkers.com/p-548-60-ton-shop-press-with-plc.aspx#sthash.1fkguTKT.dpbs

Something simple like that is all I want. I do not need to have store or program bends. Just simple input a dimension such as 2 inches and when the scale get to 2" it stops.

 

[JeffKiper]

You can do this several different ways. Its all about the programming. Just about anything you buy will have enough memory and capacity to handle multiple bend dimensions.

How have you been liking the Edwards quality? I was looking at an iron worker.

 

[DynMetalworks]

I do not own the edwards, I just knew it had a PLC from shopping them a while back.

 

[JeffKiper]

I should have explained it a little better. Just about anything you buy will have the capacity if YOU PROGRAM it to do multiple bends.

 

[atc222]

Don’t forget about any safety related items. Basically, the minute you start modifying older machinery, you become responsible for upgrading safety systems. Of course, if it’s in your garage…

Cheers