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How to change the kinematics of a five axis post by using Righ Angle Head variables ?

Creator
Creator

Right Angle Head variables are like;

global mom_head_gauge_point
global mom_head_spindle_axis

They can be use in a 5 Axis Post Builder on "Start Of Path" within a custom command.

For example I use these two variables like under. But they are not work properly every time with every kinematic model.

"...
set mom_head_spindle_axis(0) 1.0
set mom_head_spindle_axis(1) 0.0
set mom_head_spindle_axis(2) 0.0
MOM_reload_variable -a mom_head_spindle_axis

set mom_head_gauge_point(0) "100.0"
set mom_head_gauge_point(1) "0.0"
set mom_head_gauge_point(2) "0.0"
MOM_reload_variable -a mom_head_gauge_point
MOM_reload_kinematics
MOM_update_kinematics
..."

 

****************************************************************************
What strange is that if I define a HEAD above the same Operation with the same variable values under without using them in the POST,
Than they can change the output.

Machine_Tool_Tree.JPG

 HEAD.JPG

****************************************************************************

 

 

So, my question is why they are not work properly every time I use them in the Post, without using them in NX ?

 

 

Mehmet KAHYAOGLU
CNC Programming Engineer
Address :Tusas Engine Industries Inc.
Cevre Yolu No:356, PK:162
26003, Eskisehir, Turkey

16 REPLIES

Re: How to change the kinematics of a five axis post by using Righ Angle Head variables ?

Esteemed Contributor
Esteemed Contributor

Possibly because they are meant to be "output" (not input)

Note the docs for MOM_reload_variable do NOT mention that the mom_head_* variables are supported.

 

What is the problem with defining the head objects in NX, and use them there?

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 change the kinematics of a five axis post by using Righ Angle Head variables ?

Esteemed Contributor
Esteemed Contributor

And out of curiosity....

What does MOM_update_kinematics do?
I can't seem to find it in the docs...Is it something you wrote?

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 change the kinematics of a five axis post by using Righ Angle Head variables ?

Creator
Creator

It is a "Shotpeen CNC Machine Post Processor" preparing Problem.

shot-2.JPG

 

Shotpeen Machine has too many Nozzle types, but there is no tool probe in the machine.

So I want cnc programmer only select the tool from library by using the tool name for the Nozzle type and to use a UDE for extra "air distance"(for update the operation) and  post will output right. Otherwise it is not error proof. The programmer may insert a wrong number to HEAD object (by the way it is not visual) & will not easily change the output by using air distance. Otherwise programmer will offset all the lines from the beginning. And it is not going to be userfriendly.

You may say that the programmer can change air distance value to add or subtract from the HEAD object. But it will be a difficult and complicated procedure after he goes back while updating the program.

shot-4.JPG

 

shot-7.JPG

This is not always work properly.

 

Is it possible to change these HEAD variables to be mention for "INPUT", in the later version of NX  ?

 

Or is there any different way to do what I want ?

 

Thanks in advanced,

Best Regards

 

Mehmet KAHYAOGLU
CNC Programming Engineer
Address :Tusas Engine Industries Inc.
Cevre Yolu No:356, PK:162
26003, Eskisehir, Turkey

Re: How to change the kinematics of a five axis post by using Righ Angle Head variables ?

Creator
Creator
Sorry I am new here and I pressed the button "eccept as Solution".

By the way,

I did not write the MOM_update _kinematics.
It is in the MOM VARIABLE BROWSER and it says;
Maps the following legacy kinematics variables to the current kinematics variables, and is required after specifying them: mom_kin_4th_axis_center_offset, mom_kin_5th_axis_center_offset, mom_kin_pivot_gauge_offset

. I know it may not work for the HEAD variables but I used all ways to do what I wanted to do. That was the reason. It was just to try.

Re: How to change the kinematics of a five axis post by using Righ Angle Head variables ?

Esteemed Contributor
Esteemed Contributor

Interesting problem!

 

Some thoughts I had (not sure if any will satisfy your needs, but trying to suggest things that might work within NX)...

Are you tied to using the tool library? 

Could you pull tools from a template part?

Because you could set up the tools in a template part as children of a "head" object, and then use "load with parent"/"create if parent is created" setting to select the tool but then load the head as well as the tool?

 

Then use "something" ("Z offset" or tracking points or ?) to modify the air gap?

Another option is to model the actual tool as the "holder" object, then the air gap would be represented by a .01" (or whatever) dia x "air gap desired" length tool?

 

Not sure about these issues:

1) Can library tools pull a head in?

2) If library tool is in template part, is it stll a library tool when pulled into an actual part?

    (i.e. will graphical representation still work?)

3) Can heads be defined as devices, so NX will use the graphical tool representation for both the (device library) head and (tool library) holder/tool?

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 change the kinematics of a five axis post by using Righ Angle Head variables ?

Phenom
Phenom

One option would be to do the math yourself in MOM_before_motion. In this routine you can use the mom_mcs_goto locations and calculate the effect of kinematics to load mom_pos locations for post. This also helps with timing - as kinematic update can require some advance notice (to cam generator) to get the right effect.

NX10.03
Windows 7 Pro

Re: How to change the kinematics of a five axis post by using Righ Angle Head variables ?

Creator
Creator

Ok Ken_A I will try all your advices. But I have to undertand exactly what you mean.

 

I will setup a template part for the tools as you told me. And going to try to pull them. ("Because you could set up the tools in a template part as children of a "head" object, and then use "load with parent"/"create if parent is created" setting to select the tool but then load the head as well as the tool?")

 

And it make sense to me using the "Z offset" or "Tracking Point" to modify the air gap. I should have to try if it works for to extend the HEAD z (height) or to extend for the "L" (length). What do you think ?

 

On the other hand, how can I model the actual tool as the "holder" object ?

Do you mean "holder" object ;

obj.JPGthis ?

If you mean that one , than how can I represent air gap here ?

 

And how to define HEADs as a device in (device library) ?

Re: How to change the kinematics of a five axis post by using Righ Angle Head variables ?

Creator
Creator

Hi Study,

 

Your advice is a master solution but it is a master mathematician's choise. Doesn't it ?

 

I am not a mathematician but I was tried to find out a way about calculating the kinematic model of the machine.

 

I had researched lots of documents attaced if you like to see but, they seemed to me very complicated math problems. 

 

In other words if you can show me the way how to calculate different kind of machine's kinematic solutions, than it is my pleasure to learn it.

 

And also other question is "MOM_before_motion" .

I can only find "MOM_before_motion" if I open the .tcl file with WordPad.

And I find out under but I do not know how to modify it with math calculations;

#=============================================================
proc MOM_before_motion { } {
#=============================================================
global mom_motion_event mom_motion_type

FEEDRATE_SET


switch $mom_motion_type {
ENGAGE { PB_engage_move }
APPROACH { PB_approach_move }
FIRSTCUT { catch {PB_first_cut} }
RETRACT { PB_retract_move }
RETURN { catch {PB_return_move} }
default {}
}

if { [llength [info commands PB_CMD_kin_before_motion] ] } { PB_CMD_kin_before_motion }
if { [llength [info commands PB_CMD_before_motion] ] } { PB_CMD_before_motion }
}

 

If you suggest me to have a look at the "sim_math.tcl" or "ugpost_base_math.tcl" documents than I did it. Is there any explain document for these procedures ?

 

Best Regards,

Mehmet Kahyaoglu

Re: How to change the kinematics of a five axis post by using Righ Angle Head variables ?

Phenom
Phenom

I do have code for transformations - but it is owned by the company I am working for so I shouldn't share it. Generally - 3d transformations are done with 3x3 (or 4x4 with translation) matrices. You will transform the matrix by spinning around axes - then evaluate points through the matrix. The math for transforming the matrix is included in the math libraries that are delivered. The routine "MTX3_xform_csys" is found in "pb_sim.tcl" and will handle rotating the matrix around the axes. The routine "MTX3_vec_multiply" found in "ugpost_base.tcl" can be used to evaluate points through a matrix. As far as "overriding" the "MOM_before_motion" - use the "rename" feature to take the current proc and add your own code to it. I am way behind right now or I would give some code examples.

NX10.03
Windows 7 Pro

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