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How to edit postprocessor for C axis limit rotation ?

Dear all

 

I have some problem . My machine is 5 axis machine .It have head-head rotation . but C axis ( rotation axis) It has range 0- 360 . It can not rotate unlimit . It has go to 0 before machining next area . How to add  code to lift spindle on Z axis to rotation for safety and go down to area for machining.  

9 REPLIES

Re: How to edit postprocessor for C axis limit rotation ?

[ Edited ]

To handle the case where the rotary axis limit is reached & you have to reposition, do the following in post builder:

Machine tool tab -> click on "4th axis" -> click on "configure" (in "Rotary axis" section of dialog) -> change the "axis limit violation handling" option

- initially, try setting to "retract / Re-engage", post, and look at the output changes

- otherwise select "user defined" and create a custom command & tcl code to do what you want

 

 

To handle the general case, where ANY time the rotay axis moves you want to "up in Z, then rotate, then go down in Z" you'll have to add a custom command to actually

- check if rotary axis is moving (mom_out_angle_pos() and mom_prev_out_angle_pos(); if *prev* doesn't exist, set to 0 )

- move "up" in Z

- reset all variables to new position in Z (mom_pos(), mom_prev_pos(), mom_last_pos(), possibly others)

- rotate axis

- reset mom_pos() to desired position & rapid (or linear) move back down.

 

If you want to do something else, please clarify what you want

 

Ken Akerboom Sr CAx Systems Engr, Moog, Inc.
Production: NX10.0.3.5 MP5 + patch/TC11.2
I'd rather be e-steemed than e-diseaseled


Re: How to edit postprocessor for C axis limit rotation ?

Dear Ken Akerboom

 

Thank you very much for your respond. I have choose etract / Re-engage . But I look at G code It not up in Z . What is mean of  choose etract / Re-engage ?  I want to up Z when  C axis is limit . How to add custom command to do it ?  

 

Thank you very much

Re: How to edit postprocessor for C axis limit rotation ?

[ Edited ]

I don't have any experience with that setting - but in the post it only sets a "kin" variable - meaning that it leaves any action up to NX. My expectation is that if a clearance plane exists - NX will go there and then update mom_pos(3) and mom_pos(4) to alternate values (post is not involved in the decision.) The other option "User Defined" will allow you to create your own action (when clicking Handler.) With this option - the post is updated to include your code in the event that I presume is called by NX with overtravels - it is called "PB_user_def_axis_limit_action".

 

The ideal prewind/rewind scenario would be to look at the motion that a tool runs (as a whole) in a second pass. To split this motion up in feed sequences to see the range the rotary travels (maybe plus or negative) and at rapid clear locations - go back to prewind for the coming motion. Any mid cut rewinds would probably not be desirable. The approach to the motion in the operation could be a factor as well. I have never coded this in postbuilder - I think it would be difficult. I have worked on a c/l post that did it. With NX and a postbuilder post - I would probably use the Rotate UDE a lot to influence the starting position of operations.

NX10.03
Windows 7 Pro

Re: How to edit postprocessor for C axis limit rotation ?

What past versions of PB did (not sure if they changed in PB10)

If you get to a rotary axis limit, the post rapided the tool 10", repositioned the rotary axes, then rapid own 9" then feed the last 1".  Not sure what distances are used in metric posts.

 

I'm not sure of the rules when this gets triggered.  It *might* only be used when (in 5 axis case) the machine can't get to the next point using the "nearest" soultion (due to axis limits) but the "alternate" solution IS valid, so it lifts/rotates to alternate solution/re-engages

 

The variables used are:

set mom_kin_retract_type                "DISTANCE"
set mom_kin_retract_distance            10.0
set mom_kin_reengage_distance           .20

and the proc is

#=============================================================
proc ROTARY_AXIS_RETRACT {  } {
#=============================================================
# called by PB_CMD_kin_befor_motion

 

 

Ken Akerboom Sr CAx Systems Engr, Moog, Inc.
Production: NX10.0.3.5 MP5 + patch/TC11.2
I'd rather be e-steemed than e-diseaseled


Re: How to edit postprocessor for C axis limit rotation ?

[ Edited ]

That code may be added in some version of postbuilder but with PB8.5 - selecting "Retract / Re-Engage" only updated the kin variable (verified by compare of tcl) - no code is added (from having "Warning" set.) So - I assume NX would do the retract motion (or that was the intention.) Those variables may be used by NX though (I suspect.) But - the tcl does not have these variables after setting this switch in PB - and they are not in ugpost_base.tcl. I do see that PB_kin_before_motion would try to call that routine though (producing an error with this template.) So - with the right template there is probably a routine ROTARY_AXIS_RETRACT. This was starting the post with "Generic" control and head/head metric.

 

NX10.03
Windows 7 Pro

Re: How to edit postprocessor for C axis limit rotation ?

Dear all 

I am using post builder NX9.0 . I try to  selecting Retract / Re-Engage and post . But G code is same select warining( It not Retract / Re-Engage when axis is limit )   . and I can not find ROTARY_AXIS_RETRACT.   How to modify post builder for using  Retract / Re-Engage when axis is limit ?

 

Thank you very much

Re: How to edit postprocessor for C axis limit rotation ?

[ Edited ]

I don't know how your post was started out ("Controller" option) - but I just started (PB9.0.3.1) a 5 axis dual rotary heads MM post with controller library "Siemens - Sinumerik_840D" and set "Axis Limit Violation Handling" to "Retract / Re-Engage" and the routine is in the TCL. So - you could create a new post and get the logic.

NX10.03
Windows 7 Pro

Re: How to edit postprocessor for C axis limit rotation ?

Dear Study

I create new post processor that you recommand. But my G code is not have retract when axis is limit . Please show your G code that have retract . I do not know I can not get retract move.

Thank you

Re: How to edit postprocessor for C axis limit rotation ?

My comment was more on whether the code Ken mentioned would come out with a particular setting when starting up the post. At some point I wills tart a post again and trace through the logic (look at the tcl to see what they are doing.) I would have to test. Maybe someone from siemens can comment.

NX10.03
Windows 7 Pro

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