6 axis config.

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05 Sep 2012 14:23 #23919 by mario_rl
6 axis config. was created by mario_rl
Hi everybody,

I want to study a special lathe case, in order to know if it's possible to get LinuxCNC working in a very particular machine. The lathe have 4 milling heads, moving in 4 different-independent routes, since it's designed to machining truck shafts (both sides of the shaft at one time). 2 heads root up material from one side of the shaft, and 2 heads on the other side. The actual system works by reading a "copier" plate by two cams, for every side of the shaft who is milled (so there is two copier plates, one for each side of the shaft, and two cams for each copier=4 cams). Every cam is connected to a array of microswitches. And the microswitches drive a system of clutches, so that for a fixed feed velocity (x), every clutch control its (z) coordinate. So I have to control 4 (z) coordinates at a time, z1 to z4; z1 and z2 share the same (x1) movement, as they are in the same "cart", in one side of the truck shaft who is milled. And in the other side of the shaft (x2) is shared by z3 and z4. There is a PLC for translating the info from cams into clutch activations and other aux machine movements, lubrication, etc.

Also (yes, I'm afraid there's more) in two of the four milling heads, there are two milling tips, so there are 6 tips total, so that only one of the two tips in the head works at a the same time. I'ts like a tool changue.

I think it's a VERY complex configuration, and I need to decide between program every movement in the actual PLC memory (by change the actual processor by a powerful one), or leave the plc for m-codes and implement the clutch control by LinuxCNC . But I didn't ever see LinuxCNC moving more than one tool at a time. One thing is clear, I need to mount 6 encoders, in order to take off the copier plates and de cams and give a feedback signal to the trajectory generators.

I've seen and perform some tutorials on my own PC, palying with LinuxCNC pulse generators, the embeeded scope for signals, etc. And it works great. But one thing is "the theory" and other quite diferent is "the xperience".

very thanks to all. (sorry for my baaaad english)

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05 Sep 2012 14:30 #23920 by andypugh
Replied by andypugh on topic Re:6 axis config.
mario_rl wrote:

The lathe have 4 milling heads, moving in 4 different-independent routes,


The first question would be how you would represent the head movements in G-code.
If you can write the G-code then I think LinuxCNC can control it.

Would you plan on replacing the cams with a more easily programmed system?

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05 Sep 2012 14:47 #23922 by mario_rl
Replied by mario_rl on topic Re:6 axis config.
<<The first question would be how you would represent the head movements in G-code.
If you can write the G-code then I think LinuxCNC can control it. >>

You are totally rigth. I don't know if there are controls capable to execute more than a g-code file at a time in the market.
If exist, actually it's like four independent controls sharing the operator inteface.

<<Would you plan on replacing the cams with a more easily programmed system? >>

Yes. I'm afraid LinuxCNC is not the way, and it's a pity because I have really wanted to use it for the first time.

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05 Sep 2012 14:52 #23923 by andypugh
Replied by andypugh on topic Re:6 axis config.
mario_rl wrote:

You are totally rigth. I don't know if there are controls capable to execute more than a g-code file at a time in the market.

LinuxCNC can control 9 axes, but they have to be called XYZABCUVW

Normally XYZ and UVW are linear axes, with X and U parallel, Y and V parallel and Z and W parallel.
ABC are typically rotary axes with A having an axis along X, and so on.

None of this is written in stone, though.

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05 Sep 2012 16:10 #23926 by mario_rl
Replied by mario_rl on topic Re:6 axis config.
ok, but I'm afraid that all XYZABCUVW axes depends on the same g-code file. I'm not a G-code programmer, so I don't know if it is possibe to program simultaneous movements, or in other words, two tools (more than one) making diferent routes at the same time. I think there is necessary some kind of "parallel processing" for every machining head. May I be mistaked if say that, to do this work, the control needs to execute, for example, four G-01 commands at the same time?. Here you are some pictures.

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05 Sep 2012 16:17 #23928 by mario_rl
Replied by mario_rl on topic Re:6 axis config.
Sorry, I can't attach a file larger than 500kb, but every picture has almost 2,5mB. Is there one way?

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05 Sep 2012 16:35 #23929 by bigalex
Replied by bigalex on topic Re:6 axis config.
Hello mario_rl

for sure on the market you can find multi process cncs capable to run more than one g-code at a time (parallel elaboration) Siemens is one of them.
As usual it's a matter of money but the technology is available.

:blink: bigalex

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05 Sep 2012 16:43 #23930 by andypugh
Replied by andypugh on topic Re:6 axis config.
mario_rl wrote:

if it is possibe to program simultaneous movements, or in other words, two tools (more than one) making diferent routes at the same time..


It isn't easy.

I think it could be done with a filter.

Consider a requirement to move X from 0 to 10, and at the same time move U from 0 to 5 at the same speed.

G01 X10 U5 would move U at half the speed. But

G01 X5 U5
G01 X10 would have the same net effect

ie, by splitting the combined moves at every point where an axis needs to start or stop, I think it can be done.

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05 Sep 2012 16:44 #23931 by mario_rl
Replied by mario_rl on topic Re:6 axis config.
Ok, i know many platforms for multi axis, but no one that can execute several g-codes at a time. Of course siemens is not cheap as CNClinux. I think that generate the four routes by plc/pc programmig can be quite cheaper, but not a standard solution.

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05 Sep 2012 16:47 #23933 by bigalex
Replied by bigalex on topic Re:6 axis config.
mario_rl you can give a look here

www.cnc4you.siemens.com/cms/website.php?.../systemplatforms.htm

I'm talking about 840D system.

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