Re: [CAD_CAM_EDM_DRO] CNC Mill?

I was a Fagor reseller for several years and retrofitted several machine with
8000 series control. Machines ranged from Bridgeport size mills to a 52' planer
mill with a 110' bed nd two 50HP Spindles. Controls are easy to install, well
documented and extremely reliable.


First programs can be easily loaded up and down through the RS-232 port using
Fagor's DNC Software. Early controls are picky about the header characters of
the file but it works, biggest limitations on the 8020/8024/8025 is file size
since as I remember this is an 8-bit control. We would hit a stone wall on some
machines we modified to drill tube sheets somewhere around 3500 holes and
usually move to the 16-bit 8050 series controls. Fagor did have Drip-feed option
but it had problems of its own.

As to the z axis creeping down, normaly these were closed loop machine with the
in-position and following error values set via parameters stored in the control.
In this case as soon as the machine drifted to the limit of the in-position
parameter the control will atttempt to drive it back with in bounds by powering
the servos (+/-10V), if the machine could not regain control and restore
position it will e-stop locking all axis by dropping the Control OK signal which
is normally connected to the Servo Drive Enable Input. This will take the all
drives off line and motion will stop on the machine at a rate depending on how
the servos are configured. On a machine with a heavy Z-Axis however the
ball-screw will freewheel and the axis will literally fall from the sky if the
drive is suddenly taken off line. To prevent this we add a relay controlling a
Brake on the Servo Motor or Ball Screw if there as a reduction between the motor
and screw that is controlled by the Drive Ok Signal which normally connects to
an input on the control and will go low when the Drive Enable signal is
dropped. 


I beleive however there was an option to run an axis open without encoder
feedback, we never used it. This was used for position axes like column cross
travel on Horizontal Boring Mills where the axis was positioned clamped and left
in place during machining operation. If this is the case and the machine z-axis
parameter is set to open it ignore position errors and on an axis with an
unbalanced servo drive it will likely drift until it hits an end stop.


This was 15 years ago and details are fuzy but I do have the documentation still
somewhere.

nitewatchman



________________________________
From: "Armilite@..." <Armilite@...>
To: CAD_CAM_EDM_DRO@yahoogroups.com
Sent: Tue, October 4, 2011 8:10:42 AM
Subject: [CAD_CAM_EDM_DRO] CNC Mill?

 
Hello:

I'm looking at this CNC mill online. Any Idea what may be the problem with
the Z axis?


"Fagor 8025M control probably 2000 model, mill was a 83-3000 converted
to ball screws , servo motor pic, holds 24 tools in the ATC, moog brand
tool holders, I have about 20-30 tools for the Moog CNC Mill. There is a
port for down loading programs into the Fagor control. There are no handles
for manual use, jog with pendant and control also has jog functions. I have
several manuals for the machine. programming etc"

Problems with the z axis creeping down now until it reaches its stop
switch. Ron

Rich

(photo's)


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