Alignment control for a water-jet cutting system

1. A device for checking the alignment of a water jet in a water-jet cutting system which comprises a pressurized water inflow, a nozzle for forming the water jet, said nozzle opening into an abrasive powder intake chamber, and a focusing tube mounted on the outlet of this chamber, this focusing tube having an internal cylindrical channel of constant diameter for passage of the water jet, which device includes means for positioning an annular element on the outlet of the focusing tube, at a certain distance from this outlet and aligned with respect to the axis of the focusing tube, this annular element having an internal diameter equal to that of the internal channel of the focusing tube.

2. The device as claimed in claim 1 , wherein the annular element is formed by the downstream end of a cylindrical tubular end-piece fixed, for example screwed or fitted, to the downstream end of the focusing tube.

3. The device as claimed in claim 2 , wherein this tubular end-piece includes an internal cylindrical channel for passage of the water jet, this channel having a diameter greater than that of the internal channel of the focusing tube.

4. The device as claimed in claim 3 , wherein the internal channel of the end-piece terminates at its downstream end in an internal shoulder forming the tubular element.

5. The device as claimed in claim 3 or 4 , wherein the tubular end-piece includes at least one window formed in its cylindrical wall near its downstream end.

6. The device as claimed in one of claims 1 to 4 , which also includes means for reducing the water feed pressure and means for reducing the water feed flow rate, used for checking the alignment of the water jet.

7. A method for checking the alignment of the jet in a water-jet coupling system of the type described in one of the preceding claims, which method consists:

in fixing to the outlet of the focusing tube a cylindrical tubular end-piece having, at its downstream end, an annular element centered on the axis of the tube and having an internal diameter equal to that of the tube;

in supplying the cutting system with water at a reduced pressure and with a reduced flow rate, without addition of abrasive powder, in order to obtain a coherent and substantially non-divergent water jet at the outlet of the tube; and

in observing any water rebound on the annular element in the event of a misalignment of the water jet.

8. The method as claimed in claim 7 , wherein, when the system is fed at a pressure of about 2500 bar for cutting and with a flow rate of about 4.7 liters per minute, the feed pressure is reduced to about 700 bar and the flow rate to about 0.22 liters per minute in order to check the alignment of the jet.