Gas nozzle having a displaceable valve sleeve
This disclosure describes laser machining head gas nozzles that have an exit opening for passage of a laser beam onto a workpiece; an annular gap surrounding the exit opening; and a sleeve disposed and guided displaceably within the annular gap for axial displacement between a rearward and a forward position. The sleeve projects beyond the exit opening at least in the forward position, and the sleeve is tiltably mounted in the annular gap.
1. A gas nozzle for a laser machining head, the gas nozzle comprising:
an inner nozzle having a nozzle bore comprising an exit opening for passage of a laser beam onto a workpiece;
an annular gap surrounding the inner nozzle and the exit opening; and
a sleeve disposed and guided displaceably within the annular gap for axial displacement between a rearward and a forward position,
wherein the sleeve projects beyond the exit opening at least in the forward position, and
wherein the sleeve is tiltably mounted in the annular gap such that a clearance is formed between the sleeve and an external wall of the annular gap to allow the sleeve to be freely tiltable in the annular gap, and
wherein the sleeve is held within the annular gap by protrusions on an outer surface of the inner nozzle.
2. The gas nozzle of claim 1 , wherein (i) an external wall of the annular gap tapers in a conical manner in a forward direction or (ii) a sleeve wall on an external side tapers in a conical manner in a rearwards direction, or both (i) and (ii) to enable tilting of the sleeve in the annular gap.
3. The gas nozzle of claim 1 , wherein the exit opening of the inner nozzle directs a core gas flow onto the workpiece.
4. The gas nozzle of claim 3 , wherein the annular gap is formed in an outer nozzle for directing an annular gas flow onto the workpiece and the sleeve in the rearward and forward positions opens a nozzle cross-sectional area of the outer nozzle to a different degree.
5. The gas nozzle of claim 4 , wherein the inner nozzle and the outer nozzle are formed in a nozzle body, and the nozzle bore of the inner nozzle and the annular gap of the outer nozzle are interconnected by at least one connection opening.
6. The gas nozzle of claim 5 , wherein in the rearward position of the sleeve, an annular space, which is connected to the environment by a guide gap between the nozzle body and the sleeve, remains between a rear end face of the sleeve and the nozzle body, and the at least one connection opening extends from the nozzle bore into the annular space.
7. The gas nozzle of claim 1 , wherein a surface part of the sleeve on which a gas pressure acts in a forward direction is larger than a surface part of the sleeve on which the gas pressure acts in a reverse direction.
8. The gas nozzle of claim 1 , wherein an internal wall of the annular gap is formed by the outer surface of the inner nozzle.
9. The gas nozzle of claim 1 , wherein the sleeve is displaceably guided on an external wall of the annular gap.
10. The gas nozzle of claim 1 , wherein a front end face of the sleeve has a run-up slant on an internal or an external side of the front end face, or on both an internal and an external side of the front end face.
11. The gas nozzle of claim 1 , wherein the sleeve comprises a ceramic material, a temperature-resistant and electrically non-conducting material, or a plastic that is temperature resistant up to at least 100° C.
12. The gas nozzle of claim 1 , wherein the sleeve is mounted in the annular gap such that a lateral clearance is formed between the sleeve and a wall of the annular gap so as to allow the sleeve to be freely tiltable by +/−5° in the annular gap.
13. The gas nozzle of claim 1 , wherein the outer surface of the inner nozzle is conical.