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Author Topic: Punch press cylinder as Z axis  (Read 315 times)

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Punch press cylinder as Z axis
« on: January 23, 2020, 10:29:50 AM »
Good day for everyone,

I'm working in a retrofit project for a CNC punch press machine, I replaced the old electronic Palvision control system by a CSMIO/IP-S board, so my next step is to control the proportional valve for the 20 ton hydraulic cylinder. The speed of the proportional cylinder is controlled by a +/- 10V analog signal and it provides a 0-10V feedback signal to know the position.
So I was thinking in using a macro that would be called to perform every punch, but thinking further in the Gcode programming, it would be very useful to use the Canned cycles G81 to make programming easier as it only requires X and Y coordinates per line for machine to moves and "drill" (in case of a mill), and here comes the question, is there any way a script can recognize if G81 is activated and perform a punch in every line? or should I make an script to "link" the internal parameters of speed and position of Z axis to control the analog signal of the Ram?

I would appreciate if someone have a clue of how to perform this action.

Best regards.

Offline BR549

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Re: Punch press cylinder as Z axis
« Reply #1 on: January 23, 2020, 11:07:47 AM »
Replace teh 0-10v feedback with a linear encoder. Add a S/D->10v analog convertor to drive teh propotional valve and run teh axis as a normal cnc z axis.

Are your X and Y axis +- 10v analog or step direction ??

(;-) TP
Re: Punch press cylinder as Z axis
« Reply #2 on: January 23, 2020, 11:41:23 AM »
thanks for your reply.

I'm using an step/dir control card, and I couldn't find in the market an standard card to convert the step/dir signal to an analog signal.
At this point I can make the Ram go up or down with the analog output of my controller card and finding a solution with software would be very helpful.

Offline BR549

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Re: Punch press cylinder as Z axis
« Reply #3 on: January 23, 2020, 11:50:42 AM »
I dought you will find a software solution to be able to run generic Gcode. So your machine uses Step Direction drives for X and Y ? That would be unusual for such a machine. Most use analog servo drives.

(;-) TP

Offline MN300

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Re: Punch press cylinder as Z axis
« Reply #4 on: January 25, 2020, 12:14:36 PM »
This board converts step and direction to analog.

https://jtechphotonics.com/?product=dacpwm-converter-board
https://www.youtube.com/watch?v=Jqj29GKFXdo&feature=youtu.be

You will need to provide the electronics to compare the voltage from this board to the position feedback. The difference will be sent to the proportional valve. Some filtering may be required for smooth operation. A DC motor control could probably be adapted to this use.

The speed of the cylinder would be controlled by the axis feed speed. You could profile the punch speed to approach the workpiece rapidly and slow before contacting it.

The built in relay can be used to disable the valve when not in use. Otherwise if the cylinder is homed to the end of travel the valve may remain open. This would happen if the cylinder position stops changing and can't match the commanded position. A system using a linear encoder would lose steps in this case.
Re: Punch press cylinder as Z axis
« Reply #5 on: January 25, 2020, 10:17:03 PM »
well, I have no money and time to invest in convertion boards, I could managed to convert the Z axis speed into a register value but at this point I noticed the CSMIO analog output registers are not editable, so now I'm even more lost on this.