Producing parts made from thin-walled piping material

Tip and Trick – 2011-09-07

TB-DECO (V6)

Description :

The standard macros of TB-DECO used at the time of the initialisation programme and when feeding a new bar always direct the cutting tool past the bar centre at the end of the cut (to a negative X position depending on the Lx value of the tool geometry).

With regard to machining pipe material, when using an angled part off insert tool, it is imperative that the cut be stopped as soon as the internal diameter of the pipe is reached (position 1).

If this is not the case, then, if the part off tool stops its run past the theoretical centre of the bar (position 2), the insert will no longer be able to rest against the pipe wall, which could cause problems with length when feeding the next part.

Tip : One can get around this problem by juggling the cutting tool geometry and by inserting a series of small arithmetical calculations in one operation of the END_BAR.PGM program which manages deburring of the ejected part.

1. Geometry of the cutting tool:

IIt is sufficient to input a negative value in the Lx field, so as to prevent the tool tip from stopping its run past the centre of the part at the end of the cut.

For example Lx= -26.5.

2. Modification of operation 1:1 of the END_BAR.PGM program:

In the standard ISO code for this operation, the lines shown below have to be added before and after the G913 line, whilst adhering to the wording.

ISO code of operation 1:1 :

(MACRO DEBURRING EJECTED PART, TAILSTOCK RETURN, M60)
G900
G901
[@Move #1032 #3030 recopies the value of Lx in
#1032
[@Move DX #3001
[@Move DX #3030
[@Key - subtracts the Lx value from the
ø bar
[@Move #3001 DX
[@Move #3030 0 set de Lx à 0
G913
[@Move #3030 #1032 restores the initial Lx value
de Lx
[@Move DX #3001
[@Move DX #3030
[@Key + restores the initial value of the
Ø bar
[@Move #3001 DX

We would suggest that those persons requiring further details on extended programming should refer to the programming instruction, Chapter 6.6

For example :

let us take a pipe bar with an ext. dia. of 30.3 and an internal diameter of 28.

So that the cutting tool stops immediately on reaching the internal diameter, a negative Lx should be inserted in the geometry of said cutting tool. Its value is determined as follows:Lx = Ø at which cutting is to stop. In this case, Ø 26.5 mm
Modify the 1:1 operation of the END_BAR.PGM program as described above.