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SINUMERIK CNC automation systems

840D tool change

Thread Starter: OvidiuNastac   Started: 3/24/2009 3:46 PM   Replies: 5

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  3/24/2009, 3:46 PM
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Hi everyone
Recently I have encountered a strange issue on a milling machine with 840D Powerline, ShopMill and Tool Management that I retrofitted last year. The problem is: in Auto (only) when I execute a program with only two tool, that change one with other (the magazine is not moving). After first correct tool change, at the second tool change the program is stopping and I receive the message “Wait for TC acknowledgment”. I checked in PLC and the acknowledgment for magazine positioning (even if the magazine does not really move) is OK. I observed that the stop is before M06 command (cycle for tool change in which the spindle must be positioned……). Have anybody encountered such problem?
Nit
PS If I put a T0 before the second tool change (for mouving the magazine in an other position), the tool change is performed.



=== Edited by Nit @ 3/24/2009 4:28 PM [GMT ] ===


=== Edited by Nit @ 3/24/2009 4:27 PM [GMT ] ===


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  3/25/2009, 12:09 AM
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HI,

I've have had various hang ups with the tool management software.

Similar to yours waiting for an acknowledgement from plc but no command to plc issued.

The only solution is to find what works by trial and error in the problem area and then program it into the plc, your tool change cycle or both.


Its only a problem when there is no time and no money
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  3/25/2009, 5:35 PM
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Could it be this?

Traverse axes while tool is being changed

After the tool change command M06 the axes can continue travel without having to

wait for the tool change acknowledgement and, e.g., execute traversing blocks

without tool compensation. Travel only stops in a block with an compensation selected

(D no.) until the tool change is signaled by the PLC.

Requirement: MD 20270: CUTTING_EDGE_DEFAULT= 0 or = --2

Example: Traversing blocks between tool change and cutting edge selection

N10 T=“Drill18” ; Tool change preparation

N15 M06 ; Tool changeN20 D0

; Compensation deselection

N25 G00 X100 Z200 ; Traverse machine axesN30 Y150 M79

; Traverse machine axesN35 G01 D1 X10 ;

;

;

;

Activating the tool compensation.

Check whether tool has been changed. preprocessing

stop until tool change preparations are completed.

Main run waits until tool change is acknowledged

from PLC

The preprocessing stop is maintained until the tool change preparations have been

completed. The main run waits at N35 (D1) until the tool change has been executed

and acknowledged.

HTH,
SteveA

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  3/26/2009, 3:23 PM
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Hi

I don’t think that is a matter of tool compensation, because the program is something like that:

.

.

N4 G0 X100 Y 200
N 5 T=”MILL 50”

N6 M06

.

.

N 100 T=”Drill 20”

N105 M06

.

.

N 200 M02

At first tool change, everything is OK. At the second tool change, (because they rerun the program the magazine is not moving) the pointer on the screen passes over N100 and stops at N105 with “Waiting for TC acknowledgment”. In the PLC I’ve checked and it’s seems that both signals for prepare change and perform change (DB72.DBX 4.2 and DB72.DBX4.1) is coming at the same time. I checked the PLC acknowledgment for tool preparation and it’s OK, but I think that the NC wait another kind of acknowledgment since it sanded both signals. More, in the tool change cycle in the NC, I have more movement commands before the effective tool change but they are not executed because the NC stops before M06. Is the very first time when I encountered this kind of problem since the machine is running and they made many other programs on the machine and everything was OK.

By the way: I put a T0 and M06 before N5 and the tool change was performed afterwards.

Anyway thank you for your replay

Nit

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  3/26/2009, 5:41 PM
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It's not clear from the sample whether the M6 calls a subroutine or not.  If there is still a D word active, block execution will stop at the M6 until the tool acknowledgement.  Since it works with T0, which has no active D word, that seems like it might be related.

Even with a D0 programmed in the M6 subroutine, you have to set the MD parameter for cutting edge default to -2 for it to work.

SteveA

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  3/28/2009, 7:52 AM
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Yesterday, I managed to dig up dipper. First of all I want to tell you that the tool change is made partially in the NC (M06 call a subroutine in which I made all the necessary movements: spindle positioning, movement on Y and Z axis necessary for tool change when spindle is the change position DB72, loop for Block search active…) and partially in the PLC (magazine movement, effective tool change, movements necessary for tool change for the magazine  as change position DB71 and acknowledgements). I tried to change MD20700 first in 0, but the result was even worse. The tool change wasn’t completed and still the machine continuing the movement in the program. After that I changed MD 20700 in -2 but no result. After a wile I understood what it’s happening. When the NC call the M06 subroutine, due to D0 it call a REPOSA subroutine and in the same time generate a Block search command (???)  (only in NC) which bypass the normal tool change from the subroutine, and reach in a point in which due to the fact that the spindle is still rotating (M5 and SPOSA was bypassed), the PLC program stop. So I think that now I must program in the PLC the same movements as in subroutine (partially  I done for the manually load/unload command).

Anyway I think that now I can solve the problem, and I want to thank you for your ideas.

Nit

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