Laser nozzle, nozzle holder, nozzle coupling and machine tool

The invention relates to a laser nozzle, a nozzle holder, a nozzle coupling and a machine tool.

In particular, the invention relates to a laser nozzle according to claim 1, a nozzle holder according to claim 6, a nozzle coupling according to claim 11 and a machine tool according to claim 16.

A machine tool is used to manufacture and process workpieces using tools. As machine tools, for example, laser processing machines, in particular laser cutting machines are considered here. In addition, laser processing machines can also be used for engraving, structuring, welding, heat treating as well as, for example, surface layer hardening and coating, as well as for volume-building processes such as rapid prototyping or selective sintering.

For laser processing machines, a laser nozzle for guiding the laser beam is provided on the workpiece. The laser nozzle can be replaced and is therefore attached to the machine tool via a nozzle holder. The laser nozzle and the nozzle holder form a nozzle coupling.

For laser processing machines, precise alignment of the laser nozzle or the nozzle coupling is important for good and reproducible processing quality. In certain cases, in particular in the event of laser nozzles with a small beam exit opening, a cutting process-stable connection between the laser nozzle and the nozzle holder can sometimes not be guaranteed. Due to internal disturbances such as a pulsating cutting gas pressure or a thermo-mechanical interaction on a sealing ring and external disturbances such as a cleaning operation on the laser nozzle, mechanical impacts or vibrations, the laser nozzle can become off-centre with respect to the laser beam axis, thus resulting in an

unsatisfactory cutting result or even a break in the beam.

EP 2 110 198 A2 discloses a nozzle coupling for a laser processing machine having locking bolts which engage in slots and having a sealing ring. US 6 025 571 discloses a nozzle coupling having a screw connection.

JPH0452092 A discloses a nozzle which is elastically mounted in order to limit the damage in the event of a collision.

The object of the invention is to avoid the disadvantages of the prior art and to provide an improved laser nozzle. Alternative objects include providing an improved nozzle holder, an improved nozzle coupling or an improved machine tool.

This object is achieved by a laser nozzle according to claim 1, a nozzle holder according to claim 6, a nozzle coupling according to claim 11 and a machine tool according to claim 16.

The laser nozzle according to the invention, configured for a laser processing machine, comprises an outer contour configured for insertion into an inner contour of a nozzle holder, wherein the outer contour has a conical region and a locking groove configured for force- fitting engagement of a locking bolt of the nozzle holder.

The laser nozzle according to the invention has the advantage of improved process stability through a low-play fit of the nozzle, which is achieved by the combination of the conical region and the force-fitting locking groove. Furthermore, a better centring accuracy is achieved. In addition, the proposed solution is cost-effective.

It can be provided that the outer contour, in particular the conical region and the locking groove, are rotationally symmetrical with respect to a nozzle axis. This simplifies the manufacture and facilitates the insertion or introduction of the laser nozzle into a holder.

The locking groove may accordingly be an annular groove. A plurality of grooves or recesses, which are distributed over the circumference of the outer contour, can also be provided. Then, for example, a bolt can be provided as a locking element for each groove or recess.

It can further be provided that the conical region is arranged in an insertion direction of the laser nozzle in front of the locking groove. In this way, the conical region can be easily and reliably positioned in a clamp. The locking groove may be directly adjacent to the conical region or may be formed therein. It can be provided that the locking groove has a front contact surface in an insertion direction of the laser nozzle contact surface for the locking bolt. This optimizes a force- fitting connection between the locking groove or the laser nozzle and a locking bolt or a nozzle holder. Due to the defined contact of the locking bolt to a surface, the pressure can be accurately and reproducibly set.

It can also be provided that the front contact surface of the locking groove is inclined relative to the nozzle axis at an angle of 25°-35°, in particular 28° to 32°. By means of this angle, a particularly good force-fitting connection can be achieved.

The nozzle holder according to the invention, configured for a laser processing machine, having an inner contour configured for receiving a laser nozzle, provides that the inner contour has a conical region and at least one locking bolt guided in a bolt guide configured for force- fitting engagement in a locking groove of the laser nozzle. The same advantages and modifications apply as described above.

It may further be provided that the at least one locking bolt is radially inwardly

pretensioned with at least one spring. A spring can be provided, which preferably acts counter to the insertion direction on all locking bolts. The pretension by means of a spring in the direction of the locking groove allows a simple and reliable attachment mechanism.

It can be provided that a spring force of the at least one spring is formed perpendicular to an insertion direction of the nozzle holder. In this way, one or preferably a plurality of springs, most preferably one spring per locking bolt, may be provided. The spring force acting perpendicular to the insertion direction, that is in the radial direction, or the alignment of the spring(s) allows a direct force action exactly in the direction of movement of the locking bolt. So the flow of force can be simplified.

It may further be provided that the at least one locking bolt is radially inwardly

pretensioned by means of at least one elastomer element. The elastomer element, for example in the form of a ring, can reliably pretension the locking bolt or bolts in the direction of the locking groove with a simple construction.

It can be provided that the bolt guide is inclined at an angle of 45° to 50°, in particular 47°, to the axis of the nozzle holder. By means of this angle, a particularly good force-fitting connection can be achieved. The nozzle coupling according to the invention for a laser processing machine comprises a laser nozzle as described above and a nozzle holder as described above. The nozzle coupling according to the invention proposes a targeted, pairwise interaction between the external geometry of the cutting nozzle and the internal geometry of the nozzle holder in

combination with a locking mechanism, in order to ensure a cutting process-stable connection between the cutting nozzle and the nozzle holder. The same advantages and modifications apply as described above.

It can be provided that the conical region and the locking groove are designed such that when the laser nozzle is inserted and locked, the two conical regions are engaged. Through the engagement, the nozzle is easily and reliably fixed so that a good processing quality is guaranteed.

It can further be provided that the two conical regions form a seal when the laser nozzle is inserted and locked. This saves a sealing ring and thus simplifies the design of the coupling. By eliminating an elastic element, namely the sealing ring, a low-play and more process- stable centring can be achieved. In addition, the reliability is increased because the nozzles no longer stick to a sealing ring during ejection. The conical surfaces preferably have a low roughness, so that a seal is ensured. The roughness may be coordinated to a used fluid, such as a cutting gas.

It can be provided that the conical regions and the locking groove are formed such that, upon introduction of the laser nozzle into the nozzle holder, the at least one locking bolt is initially movable away from the outer contour and then into the locking groove and that the locking bolt located in the locking groove presses the two conical regions together.

Accordingly, the laser nozzle can be moved by a force in the insertion direction, for insertion, or counter to the insertion direction, for removal. The locking takes place automatically, i.e. without further active actuation.

It can also be provided that a front region of the bolt guide in the insertion direction locks with the front contact surface of the locking groove to form a differential angle of 15° to 25° when the laser nozzle is inserted and locked. The differential angle is formed between the region and the contact surface or between the two angles a and b. By means of this angle or these two angles, a particularly good force-fitting connection can be achieved.

The machine tool according to the invention, in particular a laser processing machine, having a laser for machining a workpiece, provides that at least one nozzle coupling is provided according to one of the preceding claims, wherein the nozzle coupling has a laser nozzle configured for the passage of a laser beam. The same advantages and modifications apply as described above. During operation of the laser processing machine, the nozzle coupling allows a stable beam guidance and thus good cutting results. When setting up the laser processing machine, the nozzle coupling allows a quick and reliable change of the nozzle.

Further preferred embodiments of the invention will become apparent from the other features mentioned in the dependent claims.

The various embodiments of the invention mentioned in this application are, unless otherwise stated in the individual case, advantageously combinable with each other.

The invention will be explained below in exemplary embodiments with reference to the accompanying drawings. The drawing shows:

Figure 1 a sectional view of a laser nozzle;

Figure 2 a sectional view of a nozzle holder;

Figure 3 a sectional view of a nozzle coupling consisting of the laser nozzle and the nozzle holder;

Figure 4 a detailed representation of Figure 3 with regard to the force-fitting

connection of the nozzle coupling; and

Figure 5 a schematic perspective view of a machine tool.

Figure 1 shows a schematic sectional view of a laser nozzle 100. The laser nozzle 100 here has a circular or oval cross section, in principle, however, other cross sections such as square pipe sections are possible. The laser nozzle 100 is also rotationally symmetrical about a central axis A.

The laser nozzle 100 has a main body 102 having an outer contour 104 and an inner space 106. The inner space 106 ends, in the direction of a workpiece, in a nozzle opening 108. A laser beam and optionally a fluid, such as a cutting gas, is guided through the inner space 106 and the nozzle opening 108. For receiving and attaching the laser nozzle 100 in a nozzle holder, a conical region 110 and a locking groove 112 are arranged on the outer contour 104. Ideally, the conical region 110 and the locking groove 112 are part of the outer contour 104, i.e. are formed directly therein. In an insertion direction E, which runs parallel to the central axis A, the laser nozzle 100 can be introduced into a nozzle holder. The insertion direction E runs opposite to the beam guidance in the laser nozzle 100.

The conical region 110 is arranged at the front in the insertion direction E, that is to say at the end 114 of the laser nozzle 100 away from a workpiece. In the representation of Figure 1, the conical region 110 is arranged at the top. The locking groove 112 is arranged further back than the conical region 110 in the insertion direction E. In other words, the locking groove 112 is arranged between the conical region 110 and the nozzle opening 108. In this example, both the conical region 110 and the locking groove 112 are circumferential and rotationally symmetrical.

The conical region 110 extends to the second end 114 of the laser nozzle 100 and tapers in this direction. Tapered means that the diameter of the conical region 110 at the second end 114 is smaller than in the region behind this.

The locking groove 112 has a contact surface 116 in the direction of the second end 114, whereby the locking groove 112 or the contact surface 116 is configured for the force-fitting engagement of a locking bolt of a nozzle holder or of a machine tool. The contact surface 116 of the locking groove 112 is inclined relative to the nozzle axis A at an angle a of 25°- 35°, in particular 28° to 32°, here 30°. By virtue of this construction, a locking bolt acting on the contact surface 116 can press the laser nozzle 100 with its conical region 110 into a nozzle holder and fix it there.

Figure 2 shows a schematic sectional view of a nozzle holder 200 which is configured to receive the laser nozzle 100 shown in Figure 1. The nozzle holder 200 has a main body 202 having an inner contour 204. The inner contour 204 at least partially forms the boundary of an inner space 206. The inner space 206 serves to receive the laser nozzle 100 and possibly for the passage of a laser beam and optionally a cutting gas. At an end facing the workpiece or at the front in the insertion direction E, the inner space opens into a collar 208 in order to facilitate reception of the laser nozzle 100. In the inner contour 204 or as part of the inner contour 204, a conical region 210 is formed. This conical region 210 is formed to complement the conical region 110 of the laser nozzle 100. In the insertion direction E in front of the conical region 110, a plurality of locking bolts 212 is arranged, one of which is shown here by way of example. The locking bolts 212 are movably-mounted, cylindrical bolts. These are displaceable between a locking position and an unlocking position. In the locking position shown here, at least part of the locking bolt 212 projects beyond the inner contour 204 into the inner space 206. In this locking position, the locking bolts 212 hold the nozzle 100 in the nozzle holder 200. In the unlocking position, the locking bolts 212 are located within the main body 202 and thus do not project beyond the inner contour 204 into the inner space 206.

Outside of the nozzle holder 200, a sleeve 214 is arranged, which can be engaged with the locking bolts 212. In addition, the locking bolts 212 are pressed by means of a spring 216 in the direction of the locking position. An intermediate member 218 can provide a uniform force transmission between the spring 216 and the locking bolts 212.

The locking bolt or bolts 212 are arranged in a bolt guide 220, from which the locking bolts 212 can partially penetrate into the locking groove of the laser nozzle. The bolt guide 220 is inclined at an angle b in relation to the axis A' of the nozzle holder 200. The angle b is 45° to 50°, preferably 47°.

Figure 3 shows a schematic sectional view of a nozzle coupling 300, comprising the laser nozzle 100 and the nozzle holder 200. In Figure 3, the nozzle coupling 300 is shown in the coupled state, that is to say that the laser nozzle 100 is fixed in the nozzle holder 200.

The conical regions 110 and 210 as well as the locking groove 112 and the locking bolts 212 are designed such that when the laser nozzle 100 is inserted into the nozzle holder 200, the at least one locking bolt 212 is initially movable away from the outer contour 104 and then into the locking groove 112. In the locking position, the locking bolt 212, which is partially located in the locking groove 112, presses the two conical regions 110, 210 against one another, preferably in a sealing manner. In this case, the locking bolt 212 is only in force- fitting contact with the contact surface 116.

To remove the laser nozzle 100 from the nozzle holder 200, the sleeve 214 is pushed upward, whereby the spring 216 is relaxed. Then, the laser nozzle 100 can be removed by pulling counter to the insertion direction E. Figure 4 shows a schematic perspective view of a region of the nozzle coupling in which a locking bolt engages in the locking groove. The angular relationships between the bolt guide 220 and the front contact surface 116 of the locking groove will be described with reference to figure 4.

A front region of the bolt guide 220 in the insertion direction E locks with the front contact surface 116 of the locking groove 112 to form a differential angle d when the laser nozzle 100 is inserted and locked. The differential angle d can be calculated as the difference of the angle b minus the angle a. Angle b is 45° to 50°, preferably 47°. Angle a is 25°-35°, in particular 28° to 32°, here 30°. Accordingly, the differential angle d is 15° to 25°, preferably 17°.

Figure 5 shows a schematic perspective view of a machine tool 500, such as a laser processing machine, in particular a laser cutting machine having a laser cutting head 502. The laser cutting head 502 comprises the nozzle coupling 300. The laser cutting head 502 is arranged on a movable bridge 504, so that it can be moved in at least the x and y directions. A laser source 506 generates laser light and supplies it to the laser cutting head 502 via an optical fibre 508. A workpiece 510, for example a sheet, is cut by the laser beam.

The laser nozzle 100, nozzle holder 200, nozzle coupling 300 or machine tool 500 shown here permits a simple and stable positioning and fixing of the laser nozzle 100, whereby the processing quality is improved.