Bridgeport 760/20 spindle orientation problem

hi everyone..
I am having problem with Bridgeport VMC 760/20 heidenhain 2500 control with Siemens drive. it has a Siemens drive. When we command the machine for spindle orientation M19 the spindle starts rotating on a small speed and doesn't orient. it keeps on rotating for 2-3 min and then alarm comes,' spindle not oriented' and meanwhile spindle keeps on rotating on very low speed less than 20 rpm i think.
if after rotating spindle let's say on 1000 rpm we give M19 or tool change command spindle just try to stop and then again starts rotating at low speed and doesn't orient at all.
Main thing to note is, sometimes when we just switch on the machine, it orients. but again if we try then same condition comes.
I have checked all the parameters 1 by 1.
I have checked spindle position value in MP 4210.XX.
I have checked spindle orientation speed for spindle orientation in MP 3520.1 and it is 100.
i have checked speed orientation ramp slop value MP 3410.1 it is 1
Any help regarding this shall be appreciated....

I have replaced the spindle external encoder and encoder cable. but the problem is same. there is no heidenhain service person in india...

does this machine have a umbrella type atc or a swing arm. there is some times a prox switch that needs to be made it is usally found on the rotating part of the spindle by the belt. these are used on machines with gear boxes the control is looking for a input from this prox switch.
Just a thought

hi Machineblues... thanks for the reply
its a swing type tool changer and there is no proximity on the spindle for orientation, there is only external rotary encoder...... and its Heidenhain 2500B control.

there is no tool change arm. the tool changer itself swings to spindle for tool change with a pneumatic cylinder......
wat i have chacked with the m/c plc step sequence program there is one input I1 which misses sometimes. and same time spindle doesn't orient. if we put dwell time for 5 seconds before tool change then it works for 15-20 times and then again problem comes. but if we give direct tool change than it never takes orientation.
can anyone or machine blues tell me how to check this input coz i don't have machine manual for the machine. and in electrical drawing there is no ref of input and outputs,

I am a machine repair tech in the USA. I do not have the electrical drawings either and also not formilar with this control. But there is a number of things that need to happen for a tool change to work correctly.

1.head to tool change height
2.orient spindle
3 bring tool changer to spindle
4 unlock drawbar
5 head up or lower ATC
6 rotate to tool called
7 insert tool in spindle
8 lock drawbar
9 ATC home

There is a amount of time for each thing that needs to happen. It might be doing the next before the time runs out.

There is a switch for the ATC in"under spindle" and there is also one when home "when the ATC is all the way to the left"

There is a prox switch when drawbar locked. Also when unlocked.

This ATC sounds as if it is a umbrella type. If there is no arm that swings between the ATC and the spindle. This also has to put the tool in the correct ATC position. Does not have "random tool pots"

The prox switches are sometimes on the cylinders themselves.

the problem might be somthing that comes before the orient.

I would look for a switch of some sort that tells that the head is at tool change height. (If the ATC lowers there is a switch for up and down also)


(I would try to orient spindle by it's self "not in a tool change") In MDI mode
if this works there is not a problem with the encoder on the spindle.
"This is to rule-out the orient/spindle encoder"
For most controls it would be M19

Sorry if I gave to much info.
This is how I need to look at it to find the problem.

Does the spindle stop perfectly every time you give a M5 command?

Quote:

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Originally Posted by Harmeet

I have replaced the spindle external encoder and encoder cable. but the problem is same.

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Since you have replaced the orientation encoder and cable, problem is probably on the spindle itself. When you failed on an orientation M19 command, immediately check if spindle stop perfectly by M5 command. If it fails again, there's a problem with your siemens spindle drive.

hi everyone...
thanks for the reply.....
i am also a machine tech but hadn't worked on heidenhain control....
i have checked each and every thing already and found nothing problem...
and when we give M05 its stops perfectly and it has a M25 code by which Z-Axis goes to tool change position and still if u command there M19 it won't orient....
As i have checked the spindle doesn't orient when it has M03 in its memory......
so i have changed the machine ladder so that every time either we command M19 or it comes through tool change cycle M06, it cancels the M03 or M04 if its in the memory, everytime....
As i already told u if i turn off the machine and turn on again, it takes the M19 for the first time coz we haven't command anyting...
even i tried to put M05 command in the program evertime tool changed command M06 comes, it works for the 4-5 cycle and then again it doesn't orient....
so i changed the ladder and now it is working fine from 2-3 days.....
Thanks for the reply and help.......