CN220547776U

CN220547776U - Nozzle for use in a laser machining apparatus and laser machining apparatus

Info

Publication number: CN220547776U
Application number: CN202321122239.7U
Authority: CN
Inventors: M·贝亚; D·莫克; 庞浩; J·多马施克; T·凯泽; M·胡贝尔
Original assignee: Trumpf European Ag
Current assignee: Trumpf European Ag
Priority date: 2022-05-13
Filing date: 2023-05-11
Publication date: 2024-03-01
Anticipated expiration: 2033-05-11
Also published as: WO2023217611A1; DE102022112050A1; CN117047298A

Abstract

There is provided a nozzle for use in a laser machining apparatus, the nozzle comprising: a base body with a passage opening extending through the base body from a first end to a second end along a nozzle longitudinal axis; the passage opening has a first diameter in the region of the first end; the via opening forms a parallel walled reflection section on the inside of the base body in the region of the second end, the parallel walled reflection section having a length of at least 2mm, the via opening having a smallest second diameter in the reflection section that is smaller than the first diameter; the base body has a coupling section at a first end; adjacent to the coupling section, the base body has a step on its outer circumference, which extends in the radial direction around the passage opening and which forms a circumferential cooling surface oriented substantially perpendicular to the nozzle longitudinal axis. A laser processing apparatus including the nozzle is also provided.

Description

Nozzle for use in a laser machining apparatus and laser machining apparatus

Technical Field

The present utility model relates to the field of laser processing. In particular, the present utility model relates to a nozzle for use in a laser processing apparatus, to a laser processing apparatus comprising the nozzle, and to a laser processing method using the nozzle.

Background

There are laser cutting processes in which it is advantageous for the focal point of the laser beam to be located within the cutting nozzle. If a cutting nozzle with a converging inner contour is used in such a case, it may occur that the edge region of the laser beam is reflected or absorbed inside the nozzle in the region of the nozzle mouth. Such a situation is schematically shown in fig. 2a and 2 b. On the one hand, the reflection may cause a change in the divergence of the laser beam in the edge region, which may have an adverse effect on the cutting process. On the other hand, the cutting nozzle may be heated detrimentally by the absorbed laser radiation.

DE 40 16 A1 discloses a nozzle for a laser cutting process, in which the focal point of a laser beam is arranged in the nozzle. The cutting nozzle has two characteristic areas on the inside: a converging region and a parallel walled or diverging mouth region joined in the direction of beam propagation through which the laser beam passes with the cutting gas before exiting the nozzle. The nozzle allows the focused laser beam to reflect on the inner wall of the nozzle in the mouth region of the nozzle.

The object of the present utility model is to further improve the prior art. In particular, it is intended to provide a nozzle for laser processing with a high focal point position, which ensures a high process quality in laser processing and in particular in laser cutting.

Disclosure of Invention

In order to solve the task underlying the present utility model, a nozzle for a laser processing apparatus is provided. The laser processing device may preferably be a laser cutting device, wherein the laser beam is focused in the laser cutting head by means of a focusing optical unit and is directed together with the cutting gas beam towards the workpiece to be cut via a nozzle, which may be mounted on the laser cutting head.

The nozzle includes a base with a passage opening extending therethrough along a nozzle longitudinal axis from a first end to a second end of the base. The base body may preferably have a rotationally symmetrical shape with respect to the nozzle longitudinal axis. The nozzle channel may preferably have a circular cross-section.

The passage opening has a first diameter in the region of the first end. Furthermore, the passage opening forms a parallel-walled reflection section on the inside of the base body in the region of the second end, which parallel-walled reflection section has a length (in the direction of the nozzle longitudinal axis) of at least 2mm. The via opening has a smallest second diameter in the reflective section, which is smaller than the first diameter. The term "parallel walled" includes that the reflective section (or the inner wall of the substrate in the reflective section) is slightly inclined at a small angle, e.g. at most 2.5 deg., with respect to the longitudinal axis of the nozzle.

The base body has a coupling section at a first end thereof. In the coupling section, the base body is designed for coupling to a nozzle holder of a laser processing head, in particular a laser cutting head. For this purpose, the base body may preferably have a thread in the coupling section. Adjacent to the coupling section, the base body has a step on its outer circumference, which extends in the radial direction around the passage opening and which forms a circumferential cooling surface oriented substantially perpendicular to the nozzle longitudinal axis.

The nozzle is generally formed such that the edge region of the laser beam (whose focal point is located within the nozzle, precisely upstream of the reflection section in the direction of beam propagation) can reflect on the inner wall of the nozzle base body when passing through the reflection section. In this way, the absorption of laser radiation and thus the heating of the nozzle can be reduced compared to a conical nozzle inner profile. The length of the reflective section is large enough to achieve these advantageous effects. This advantageously improves the reflection properties of the nozzle in this region if the passage opening in the reflection section has a circular cross section. In other words, the base body may preferably have a cylindrical (possibly slightly conical) inner contour in the reflection section.

The nozzle according to the utility model allows cutting with a relatively large beam diameter in the nozzle, whereby a high cutting speed can be achieved with good cutting edge quality, especially when cutting in a high power range (e.g. at a laser power of not less than 6 kW), especially when flame cutting a metal workpiece (especially made of structural steel, less often also made of nonferrous metal) with oxygen as cutting gas. In particular, the beam diameter within the nozzle can be chosen to be only slightly smaller than the diameter of the passage opening in the reflection section.

Although the internal profile of the nozzle is optimized compared to a nozzle with a conical nozzle opening, heating of the nozzle cannot be completely avoided when laser radiation is incident in the reflective region. For this reason, a suitable cooling solution is required in order to ensure a high shape stability of the nozzle in laser processing and/or in order to avoid, for example, tempering of the substrate in the reflective region, which tempering may adversely affect the absorption properties. In order to improve cooling, the nozzle according to the utility model has a cooling surface. The cooling surface is used for radiating heat to the surrounding environment or the cooling medium. In operation of the nozzle, the cooling surface is directly adjacent to the preferably actively cooled nozzle holder of the laser processing head. In this way, heat may be dissipated more efficiently and the nozzle may be efficiently included in the active cooling of the laser processing head.

In general, in laser processing using the nozzle according to the utility model, in particular in laser cutting with high laser power and high focal position, an improved process quality can be achieved compared to the prior art.

Preferably, the second diameter of the passage opening is at least 1.4mm, preferably at least 1.6mm.

The length of the reflective section of the via opening may be at most 10mm, preferably at most 7.5mm. It has been found that too long a length of the reflective section has a detrimental effect on the machining process, in particular in the case of laser cutting, in particular when penetrating the material to be cut. According to a preferred variant, the length of the reflecting section may be between 2mm and 5mm. Too long parallel-walled reflecting segments may have a disturbing effect if the machining process is observed through the nozzle by means of a camera.

The cooling surface of the substrate may preferably have a width of at least 4mm. For example, the cooling surface of the base body may have a width of approximately 5mm, which corresponds in particular to the difference between the inner diameter and the outer diameter of the cooling surface. The cooling effect can be improved by increasing the size of the cooling surface.

The base of the nozzle may preferably have a thickness (or wall thickness) of at least 2mm, preferably at least 3mm, in the region between the cooling surface and the second end of the base. By implementing the nozzle solid with a nozzle wall of minimum thickness formed by the base body, a sufficient heat dissipation from the second end to the cooling surface and to the coupling section can be ensured. In the coupling section, that is to say between the cooling surface and the first end of the base body, the base body can have a smaller thickness or wall thickness, since in operation of the nozzle the coupling section is in direct mechanical contact with the nozzle holder, to which heat is dissipated.

The base body preferably has a thread in the coupling section. Threads may be used to connect the nozzle to the nozzle holder of the laser processing head. Furthermore, at the transition between the coupling section and the circumferential step, the base body can have a bevel, which forms a stop surface when the nozzle is screwed into the nozzle holder. The bevel or stop ramp is preferably dimensioned such that a gap remains between the cooling surface and the nozzle holder when the nozzle is screwed into the nozzle holder. This gap serves to avoid stresses due to differential thermal expansion. Furthermore, the bevel may be used to center the nozzle when screwing the nozzle into the nozzle holder of the processing head.

The base of the nozzle may preferably be made of a material having a high thermal conductivity (e.g. at least 300W/mK, preferably at least 350W/mK, e.g. about 355W/mK). In this way, the heat dissipation of the nozzle can be improved. Furthermore, the base body may preferably be made of an electrically conductive material for a distance sensor system for implementing the laser processing method. In particular, the substrate may be composed of copper or copper alloy. The base body is also preferably integrally formed.

The substrate may have a surface roughness of at most Rz 10, preferably at most Rz8, for example Rz 6 or less on its inner surface in the region of the reflection section. The reduction in surface roughness results in an improvement in the reflective properties of the nozzle in this region. The improved reflection properties in the reflection region allow a further reduction in the heating of the nozzle during operation. The surface of the substrate may preferably be polished in the region of the reflection section. Alternatively or additionally, the substrate may have a highly reflective surface coating, for example a nickel-based coating, in the region of the reflective section. The nickel plating can, for example, counteract degradation of the reflection properties of the substrate in the region of the reflection section (for example, due to the formation of tempering colors) during operation of the nozzle.

The base body may have an outer contour which may be divided into further sections after the coupling sections from the first end. After the coupling section, the base body can accordingly have a joining section which extends from the step in the direction of the second end, wherein the base body has its maximum outer diameter in the joining section and/or wherein the base body has a polygonal cross section or a polygonal outer contour in the joining section. The engagement section can preferably be formed such that it can be gripped by means of a gripping tool, for example a wrench, and introduced into a socket (Fassung) of the nozzle holder, in particular screwed therein. This can be done automatically, for example by means of a nozzle changer, as described for example in EP 2 589 458 B1 of the applicant. The base body preferably has 6 flat joining surfaces along its outer circumference in the joining section, wherein two joining surfaces adjacent in the circumferential direction are arranged at an angle of 60 ° to each other. The distance between two opposing engagement surfaces is preferably between 23mm and 25mm, in particular between 23.9mm and 24 mm.

Further in the direction of the second end, the base body of the nozzle may have a bearing section, in which the outer diameter of the base body preferably tapers. In other words, the base body has a conically tapering shape in the bearing section in the direction of the second end. The support section can be divided in multiple stages into regions having different taper angles, wherein the taper angle preferably decreases in the direction of the second end relative to the nozzle longitudinal axis. The conically tapering circumferential surface in the support section of the base body can be used, for example, in a nozzle changer as a stop surface for the nozzle receptacle.

The support section may engage a parallel walled transition section, preferably a cylindrical transition section, in the direction of the second end of the base body. The transition section may preferably have a length which is at least as long as the length of the reflection section of the passage opening, wherein the diameter of the base body in the transition section may be at least 8mm, preferably at least 10mm.

The transition section may preferably be joined by a mouth section, wherein the diameter of the base body narrows from the transition section towards the second end of the base body. In other words, the mouth section forms a bevel at the second end of the base body. The base body preferably has a minimum outer diameter at its second end. The (smallest) outer diameter at the second end of the substrate (i.e. the outer diameter adjacent the nozzle end face) is preferably at least 1mm, more preferably at least 3mm larger than the inner diameter of the substrate in the reflective region. The angle of the bevel forming the mouth section is at least 30 ° and preferably between 40 ° and 60 ° with respect to the nozzle longitudinal axis, or at most 60 ° and preferably between 30 ° and 50 ° with respect to the nozzle end face. In this way, the minimum wall thickness required for the substrate can be maintained. One advantage of the bevel is that: in operation, the nozzle can slide better over irregularities on the workpiece surface or over the workpiece portions that are cut away, slightly inclined in the remaining grid.

The cumulative length of the transition section and the mouth section of the base along the nozzle longitudinal axis may be at least 8mm, preferably between 8mm and 11 mm.

In general, the substrate may have a length of between 24mm and 27mm, preferably about 25.5 mm. Furthermore, for the outer contour of the base body, it is preferable that: the outer diameter of the base body in a region extending over at least 15mm and at most 20mm in the direction of the nozzle longitudinal axis from the second end of the base body is preferably not more than 18mm in order to enable a compact construction of the nozzle and to keep the interference profile of the nozzle adjoining the nozzle outlet opening (interference with the inclined portion at the time of laser cutting) to a minimum.

The preferred boundary conditions for the outer diameter of the nozzle base ensure that the wall thickness of the nozzle in the region of the cylindrical nozzle channel is sufficiently large in order to be able to dissipate heat along the nozzle wall in the direction of the coupling section and the cooling surface.

The base of the nozzle may have an internal profile formed by the passage opening, which internal profile comprises, in addition to the reflective section at the second end of the base, a funnel-shaped converging section leading to the reflective section. The base body may have a maximum inner diameter at an end of the converging section remote from the reflecting section. Furthermore, the inner surface of the base body may have a preferably constant inclination angle in the converging section of at most 25 °, preferably at most 20 °, with respect to the nozzle longitudinal axis, so as not to jeopardize the minimum wall thickness required for the base body. Finally, the converging region may have a length that is greater than the length of the reflecting section. In this way, a uniform flow of cutting gas through the nozzle can be achieved when used in a laser cutting apparatus. In general, the convergence region may have a length corresponding to the difference between the length of the base body and the length of the reflection section at most.

In addition to the converging and reflecting sections, the inner profile of the base body may also have parallel walled connecting sections extending from the first end of the base body to the start of the converging section.

In principle, it may be preferable for the base body of the nozzle to have a circular cross section on the outside, at least in the transition section and the mouth section, and on the inside, at least in the reflection section. In this way, the wall thickness of the base body can be maximized in critical areas of the reflection section, in which the base body heats up particularly strongly in operation in the high focal position, while the nozzle has the smallest possible outer diameter.

To further improve the heat dissipation, the nozzle may further comprise a heat conducting element, which is composed of a flexible/yielding material and may be mounted on the cooling surface of the substrate. In the context of the present utility model, a flexed material is understood to be a material having an elastic modulus between 400MPa and 1100 MPa. In operation of the nozzle, the heat-conducting element can therefore be arranged in a gap between the cooling surface of the nozzle and a surface of the nozzle holder opposite the cooling surface. The heat conducting element improves the heat dissipation from the nozzle via the cooling surface to the (preferably actively cooled) nozzle holder without significantly affecting the movement play ensured by the gap between the cooling surface and the nozzle holder. The heat conducting element may for example be constituted by graphite. The heat-conducting element can be glued to the cooling surface or clamped at the coupling section or at the transition between the coupling section and the cooling surface. The heat conducting element may preferably be formed in a ring shape or e.g. C-shape and has a width at most corresponding to the cooling surface. The thickness of the heat conducting element may preferably be chosen such that, when the nozzle is fastened to the nozzle holder, in particular screwed therein, the thickness of the heat conducting element is slightly greater than the thickness of the gap formed between the cooling surface and the surface of the nozzle holder opposite the cooling surface (for example about 1 mm).

Additionally or alternatively, the base of the nozzle may have at least two cooling channels, which are preferably arranged at equal intervals around the longitudinal axis of the nozzle along the periphery of the base. In this case, each of the cooling channels can extend from the cooling surface of the step through the joining section and lead to the support section of the base body. In operation of the nozzle, the cooling channel may be loaded with a cooling liquid, in particular water, by a nozzle holder, to which the nozzle may be fastened. The cooling liquid can be guided under pressure through the cooling channel and directed at the surface of the workpiece to be machined, for example to be cut. This produces a spray that cools the workpiece during processing. Thus, both the nozzle and the workpiece may be actively cooled during processing.

In order to solve the task underlying the present utility model, a laser processing device for processing a workpiece by means of a laser beam is also provided. The laser processing device may in particular be a laser cutting device. The laser machining apparatus comprises at least one laser beam source for generating a machining laser beam. Furthermore, the laser processing device comprises at least one laser processing head with a laser processing optical unit, a nozzle holder and a nozzle according to one of the variants described above. In operation of the laser processing device, the laser processing beam can be focused by means of the laser processing optical unit and can be directed through the nozzle holder and the nozzle towards the workpiece to be processed.

The nozzle holder preferably comprises cooling means. The cooling means may for example comprise a channel system through which a cooling fluid (e.g. a cooling liquid or a cooling gas) may be led in order to remove heat from the nozzle holder and in this way actively cool the nozzle holder.

In order to solve the task on which the utility model is based, a method for laser machining a workpiece by means of a laser machining device having a nozzle according to one of the variants described above is also provided. According to the method, a laser beam is directed through a base body of a nozzle toward a workpiece to be processed, wherein a focal point of the laser beam is located within the base body and above a reflection section, such that a portion of the divergent laser beam is reflected within the reflection section on an inner wall of the base body.

In the case of precisely parallel-walled reflecting segments, the divergence angle of the laser beam in the reflecting segment, which can be incident on the inner surface of the nozzle base body, is preferably at most 3 °. In particular, the divergence angle of the laser beam (relative to the nozzle longitudinal axis) may be between 1.5 ° and 2.75 °.

The laser processing method is preferably a flame cutting method, and the workpiece is preferably a workpiece composed of structural steel in the form of a plate or a tube. The flame cutting method is characterized by using oxygen or an oxygen-containing gas as a cutting gas, which causes an exothermic reaction with a material to be cut during cutting, and in this way improves cutting performance.

In the laser processing method, an (possibly cumulative) input power of at least 6kW of the laser processing beam is preferably used. As the laser power increases, the risk of critical heating of the nozzle increases. Thus, as the laser power increases, the need for an appropriate cooling scheme for the nozzle provided by the present utility model increases.

In the case of the application of the method according to the utility model as a flame cutting process, the focal diameter of the laser beam in the nozzle may preferably be between 170 μm and 1100 μm. Furthermore, as laser processing beam, a solid-state laser beam can be preferably used, which is guided from a laser beam source to a laser processing head by means of an optical fiber (so-called transmission fiber). The optical imaging of the end of the optical fiber on the surface of the workpiece to be processed can be performed at a magnification of 1.8 to 3 times under the control of the processing optical unit in the laser processing head. In the case of laser flame cutting, in particular oxygen at a pressure of between 0.4 bar and 1.2 bar can be used as process gas.

The utility model enables laser processing, in particular cutting, to be carried out with a larger beam diameter in the nozzle. In the case of laser cutting, in particular in the case of laser flame cutting using oxygen as process gas, in this way a higher laser power of at least 6kW can be used and thus a higher cutting speed can be achieved, while the quality of the cut edges is good.

Drawings

The following description of the preferred exemplary embodiments serves to explain the present utility model in more detail in conjunction with the figures,

in the drawings:

FIG. 1 shows a laser processing head suitable for receiving a nozzle according to the present utility model;

fig. 2a to 2b schematically show reflections on the inner wall of a nozzle according to the prior art;

FIG. 3 schematically illustrates reflection on the inner wall of a nozzle according to the utility model;

fig. 4a to 4c show different views of a nozzle according to the utility model;

fig. 5a to 5b show different nozzles according to the utility model in cross-section;

fig. 6a to 6c show further nozzles according to the utility model in cross-section; and

fig. 7 shows a laser processing apparatus suitable for use with a nozzle according to the present utility model.

For simplicity, functionally identical or functionally similar features are provided with the same reference numerals in the figures.

Detailed Description

Fig. 1 shows a laser processing head 10 for a beam processing apparatus, such as a laser cutting apparatus. The processing head 10 has a nozzle 12 for a processing beam (here a laser beam) and a process gas (here a cutting gas). During operation of the processing head 10, a laser beam and process gas are emitted from the nozzle 12 in a beam emission direction 14. Furthermore, the processing head 10 has a plurality of optical elements (not visible here), for example one or more protective glass elements and a focusing lens 18.

The processing head 10 also has a nozzle holder 20 with cooling elements. To cool the processing head 10, a cooling gas (e.g., compressed air or nitrogen) is directed through the cooling elements of the nozzle holder. For introducing cooling gas into the cooling element 20, a cooling gas connection 22 is provided. Process gas is introduced into the process head 10 through a separate process gas connection 24. The cooling gas and the process gas are also guided separately from one another within the processing head 10 so that they do not mix.

Fig. 2a and 2b schematically illustrate aspects of laser cutting with a high focus position using a conventional converging nozzle 12. Due to the high focal position, the laser beam has diverged within the nozzle 12 such that an edge region of the laser beam (shown here by way of example by line B) may be incident on the inner surface of the nozzle. Due to the large angle of illumination relative to the converging nozzle inner surface, a relatively large portion of the glancing laser radiation may be absorbed in the nozzle, which results in heating of the nozzle. The reflected laser radiation widens the laser beam strongly when it exits the nozzle, which can interfere with the cutting process. For example, the edge regions of the laser beam can be deflected by reflection at the nozzle mouth, so that they miss the cutting gap and are coupled into the workpiece 68 to be cut beside the cutting gap (see fig. 2 a), or are coupled into the workpiece 68 at a large angle in the upper region of the cutting gap (see fig. 2 b). Both of these situations have an adverse effect on the cutting process.

In contrast, fig. 3 schematically shows the situation during laser beam cutting with a high focus position using the nozzle 12 according to the utility model. The glancing edge region B of the divergent laser beam is reflected into the cutting gap due to the parallel walled reflection section of the passage opening at the lower end of the nozzle 12. Due to the small angle of incidence on the inner wall of the nozzle, the fraction of laser radiation absorbed in the nozzle is also reduced and thus the overheating of the nozzle is counteracted.

In fig. 4a to 4c, the nozzle 12 according to the utility model is shown in a number of external views. The construction of the illustrated nozzle 12 is described in more detail below in connection with fig. 5a and 5 b. Fig. 5a and 5b show two different variants of the nozzle 12 according to the utility model. In both cases, the nozzle 12 has a base 120 with a passage opening 121. The nozzle 12 according to fig. 5a and 5b differs only in the configuration of the passage opening 121. The outer shape of the nozzle 12 corresponds to the illustrations according to fig. 4a to 4c, respectively.

The base 120 of the nozzle 12 extends rotationally symmetrically about the nozzle longitudinal axis 12x and has an upper first end 120-a and a lower second end 120-z. From the first end 120-a, the outer profile of the substrate 120 may be divided into a plurality of sections. At the first end 120-a, the base 120 has a coupling section 120-1. Preferably, threads 122 are formed in the coupling section 120-1, with which the nozzle 12 or its base 120 can be screwed into complementary threads of a nozzle holder. In engagement with the coupling section 120-1, the diameter of the base 120 suddenly increases in the form of a circumferential step that introduces the engagement section 120-2. On the engagement section 120-2, a plurality of flats may be arranged, which flats are designed for engaging a tool for screwing in or unscrewing the nozzle 12. The joint surface can be seen in fig. 4a to 4 c. A cooling surface 123 is formed on the upper side of the step, through which heat can be dissipated from the base body 120 to the surroundings in the direction of the nozzle holder during operation of the nozzle 12. At the transition between the coupling section 120-1 and the cooling surface, a ramp 124 or ramp 124 is formed, which serves as a stop and centering aid when screwing the nozzle 12 into the nozzle holder.

The engagement section 120-2 engages the conically tapered support section 120-3. On the inclined bearing surface of this section (which may have a plurality of subregions with different taper angles), the nozzle 12 can be supported in a nozzle box when not mounted on the laser processing head. Below the support section 120-3, a parallel-walled transition section 120-4 is joined, which transitions at the second end of the base body 120 into a mouth section 120-5 which tapers conically again.

On the inside, the base body 120 can likewise be divided into sections which are predefined by the shape of the passage opening 121. At the second end 120-z of the lower portion, a parallel wall reflection section 121-3 is formed. Further above the base 120, the passage opening 121 forms a funnel-shaped converging section 121-2 which opens into a reflecting section 121-3. The converging section 121-2 may in principle extend from the first end 120-a of the substrate 120 to the reflecting section 121-3 (see fig. 6 c). However, as shown in fig. 5a and 5b, a parallel wall connecting section 121-1 may be additionally provided, which extends between the first end of the base 120 and the converging section 121-2.

The passage opening 121 has an inlet diameter 121-4 at the first end 120-a of the base body 120 and an outlet diameter 121-5 at the second end 120-z of the base body 120, wherein the outlet diameter 121-5 corresponds to the diameter of the passage opening 121 in the reflective section 121-3. The diameter 121-5 may preferably be at least 1.4mm (e.g., between 1.6mm and 3 mm) and the length of the reflective section 121-3 is at least 2mm. For example, the diameter 121-5 may be between 1.5mm and 1.6mm, with the length of the reflective section being about 3.5mm. If the inner wall of the base body 120 in the reflection region 121-3 has a slight angle with respect to the nozzle longitudinal axis 12x, the smallest inner diameter of the base body 120 can decisively be the diameter 121-5 in the reflection section 121-3.

The substrate 120 may have a total length L of 23mm to 27mm, in particular about 25.5 mm. In the transition section 120-4, the substrate 120 may have an outer diameter 120-8 of at least 8mm, preferably at least 10mm. Furthermore, up to a distance of at least 15mm and at most 20mm from the second end 120-z, the substrate 120 may have a thickness of at most 18 mm. In the mouth region 120-5, the substrate 120 may have a cone angle of at least 30 ° and at most 50 ° relative to the nozzle end face at the second end 120-z of the substrate 120. The nozzle end face may be oriented substantially perpendicular to the nozzle longitudinal axis 12x and have an outer diameter 120-7 that is at least 1mm, preferably at least 3mm, greater than the (inner) diameter 121-5 of the nozzle in the reflective region 121-3. The converging region 121-2 inside the nozzle may preferably have a cone angle of at most 50 °, preferably at most 40 °, and a length of at least 4mm, preferably at least 6mm, more preferably at least 8 mm. In the support section 120-3, the outer surface of the base body 120 may have an inclination of, for example, 50 ° with respect to the nozzle longitudinal axis 12x in a first sub-region adjoining the engagement section 120-2. In a second sub-region of the support section 120-3 adjoining the transition section 120-4, the outer surface of the substrate may be inclined at 33.55 ° relative to the nozzle longitudinal axis 12 x.

In fig. 6a to 6c, further nozzles 12 according to the utility model are shown in each case in cross-section. The nozzle 12 according to fig. 6a has a heat-conducting element 125a which has the shape of a ring and is glued to the cooling surface 123 of the base body 120. The nozzle 12 according to fig. 6b likewise has a heat-conducting element 125b, which is firmly clamped to the base body 120 directly above the cooling surface 123. The heat conducting element may be made of graphite, for example, and serves to improve the heat dissipation from the cooling surface 123 to the contact surface of the nozzle holder during operation of the nozzle 12. The nozzle 12 according to fig. 6c has at least two cooling channels 126. During operation of the nozzle, the cooling channel 126 can be acted upon with a cooling fluid, in particular water, and the nozzle 12 and additionally the workpiece to be machined, through which the cooling fluid is directed, are actively cooled.

Fig. 7 shows a beam processing device 62 here in the form of a laser cutting device. As shown in FIG. 7The laser cutting device 62 is shown, for example, with CO ₂ The laser acts as a beam source 64. Alternatively, the beam source may be a solid state laser or a diode laser, for example. The laser cutting apparatus 62 further comprises a displaceable processing head 10 (see fig. 1) and a (stationary) workpiece holder 66 on which a workpiece 68 is arranged. The beam source 64 generates a laser beam 70 that is directed from the beam source 64 to the processing head 10. The laser beam 70 is directed towards the workpiece 68 by means of a focusing optical unit arranged in the processing head 10.

The laser cutting device 62 is connected to a gas supply 72. The gas supply 72 provides, on the one hand, a process gas, here a cutting gas. The process gas may be, for example, nitrogen or oxygen. In particular in the case of a flame cutting process, the process gas (in this case oxygen) may be supplied to the nozzle 12 of the processing head 10 at an overpressure of between about 0.4 bar and 1.2 bar.

The gas supply device 72 on the other hand supplies the cooling element 20 with cooling gas. The cooling gas may be, for example, nitrogen or compressed air.

The laser cutting apparatus 62 also has a machine controller 74 that is programmed to move the processing head 10 relative to the workpiece 68 (which is stationary, for example, here) in a manner corresponding to the cutting profile. The machine controller 74 also controls the power of the beam source 64, for example, for performing a flame cutting process.

Claims

1. A nozzle for use in a laser machining apparatus, the nozzle (12) comprising:

a base body (120) with a passage opening (121) extending through the base body (120) from a first end (120-a) of the base body (120) to a second end (120-z) of the base body along a nozzle longitudinal axis (12 x);

wherein the passage opening (121) has a first diameter (121-4) in the region of the first end (120-a);

wherein the via opening (121) forms a parallel walled reflection section (121-3) on the inside of the base body (120) in the region of the second end (120-z), the parallel walled reflection section having a length of at least 2mm, wherein the via opening (121) has a smallest second diameter (121-5) in the reflection section (121-3) that is smaller than the first diameter (121-4);

wherein the base body (120) has a coupling section (120-1) at the first end (120-a); and is also provided with

Wherein, adjacent to the coupling section (120-1), the base body (120) has a step on its outer circumference, which extends in a radial direction around the passage opening (121), and which forms a circumferential cooling surface (123) oriented perpendicularly to the nozzle longitudinal axis (12 x).

2. The nozzle according to claim 1,

characterized in that the second diameter (121-5) is at least 1.4mm.

3. The nozzle according to claim 1 or 2,

characterized in that the length of the reflecting section (121-3) is at most 10mm.

4. The nozzle according to claim 1 or 2,

characterized in that the cooling surface (123) has a width of at least 4mm.

5. The nozzle according to claim 1 or 2,

characterized in that the base body (120) has a thickness of at least 2mm in the region between the cooling surface (123) and the second end (120-z).

6. The nozzle according to claim 1 or 2,

characterized in that the base body (120) has a thread in the coupling section (120-1); and is also provided with

Wherein the base body (120) has a bevel (124) at the transition between the coupling section (120-1) and the step, which bevel forms a stop surface when the nozzle (12) is screwed into the nozzle holder (20) of the laser processing head (10).

7. The nozzle according to claim 1 or 2,

characterized in that the base body (120) is made of a material having a high thermal conductivity.

8. The nozzle according to claim 1 or 2,

characterized in that the base body (120) has a surface roughness of at most Rz 10 on its inner surface in the region of the reflection section (121-3).

9. The nozzle according to claim 1 or 2,

characterized in that the base body (120) has an outer contour which can be divided, starting from the first end (120-a) after the coupling section (120-1), into the following sections:

-a joining section (120-2) extending from the step in the direction of the second end (120-z), wherein the base body (120) has its largest outer diameter in the joining section (120-2) and/or the base body (120) has a polygonal cross section in the joining section (120-2);

-a support section (120-3) in which the outer diameter of the base body (120) narrows;

-a parallel walled transition section (120-4), wherein the length of the transition section (120-4) is at least as long as the length of the reflection section (121-3) of the passage opening (121), and wherein the diameter of the base body (120) in the transition section (120-4) is at least 8mm; and

-a mouth section (120-5) in which the diameter of the base body (120) narrows from the transition section (120-4) towards a second end (120-z) of the base body (120).

10. The nozzle according to claim 1 or 2,

characterized in that the base body (120) has an inner contour formed by the passage opening (121), which inner contour comprises, in addition to a reflection section (121-3) at the second end (120-z) of the base body (120), a funnel-shaped converging section (121-2) opening into the reflection section (121-3);

wherein the base body (120) has a maximum inner diameter at an end of the converging section (121-2) remote from the reflecting section (121-3);

wherein the inner surface of the base body (120) has an inclination angle of at most 50 ° in the converging section (121-2) with respect to the nozzle longitudinal axis (12 x); and/or

Wherein the converging section (121-2) has a length that is greater than the length of the reflecting section (121-3).

11. The nozzle according to claim 1 or 2, the nozzle (12) further comprising:

-a heat conducting element (125 a,125 b) made of a flexible material and mountable on a cooling surface (123) of the base body (120).

12. The nozzle according to claim 9,

characterized in that the base body (120) also has at least two cooling channels (126) arranged around the nozzle longitudinal axis (12 x) along the periphery of the base body (120);

wherein each of the cooling channels (126) extends from a cooling surface (123) of the step through the joint section (120-2) and leads to the support section (120-3).

13. The nozzle according to claim 2,

characterized in that the second diameter (121-5) is at least 1.6mm.

14. A nozzle according to claim 3,

characterized in that the length of the reflecting section (121-3) is at most 7.5mm.

15. The nozzle according to claim 5,

characterized in that said thickness is at least 3mm.

16. The nozzle according to claim 7,

characterized in that the substrate (120) is made of copper or a copper alloy.

17. The nozzle according to claim 8,

characterized in that the base body (120) has a surface roughness of at most Rz8 on its inner surface in the region of the reflection section (121-3).

18. The nozzle according to claim 8,

characterized in that the base body (120) has a surface roughness of at most Rz 6 on its inner surface in the region of the reflection section (121-3).

19. The nozzle according to claim 9,

characterized in that in the support section, the outer diameter of the base body (120) tapers.

20. The nozzle according to claim 9,

characterized in that the transition section (120-4) is cylindrical.

21. The nozzle according to claim 9,

characterized in that the diameter of the base body (120) in the transition section (120-4) is at least 10mm.

22. The nozzle according to claim 10,

characterized in that the angle of inclination is at most 40 °.

23. The nozzle according to claim 10,

characterized in that the tilt angle is constant.

24. The nozzle according to claim 12,

characterized in that the at least two cooling channels are arranged at equal intervals around the nozzle longitudinal axis (12 x) along the circumference of the base body (120).

25. A laser machining device for machining a workpiece (68) by means of a laser beam (B), characterized in that the laser machining device (62) comprises:

at least one laser beam source (64) for generating a laser beam (B);

at least one laser processing head (10) having a laser processing optical unit, a nozzle holder (20) and a nozzle (12) according to one of the preceding claims 1 to 24;

wherein the laser beam (B) can be focused by means of the laser processing optical unit and can be directed through the nozzle holder (20) and the nozzle (12) towards a workpiece (68) to be processed.

26. The laser processing apparatus according to claim 25,

characterized in that the nozzle holder (20) comprises cooling means.