Laser processing head

Abstract

Laser processing head for a machine (1) for processing workpieces and / or for producing shaped bodies by selectively solidifying material powder into contiguous areas using a laser beam, comprising an optical module (2) and a focusing module (13), wherein the focusing module (13) comprises: a cylindrical support housing which is arranged in a correspondingly shaped cylindrical recess in the optical module (2); a focusing optic (14); and Fastening means (16) for detachably attaching the focusing module (13) to the optical module (2), wherein the fastening means (16) are two clamping bolts arranged on an upper edge of the focusing module (13); wherein the optical module (2) has receptacles (11) with a hydraulic, pneumatic or spring-loaded mechanism for clamping the clamping bolts which are arranged at an upper edge of the cylindrical recess; wherein the mechanism for automatic opening and closing is configured to allow automatic changing of the focusing module (13).

Description

[0001] The present invention relates to a laser processing head for a machine for processing workpieces and / or for producing shaped bodies by selectively solidifying material powder into contiguous areas using a laser beam. The term laser machine tool, or simply machine, is used hereinafter to refer collectively to the various types of machines for processing / manufacturing / producing a workpiece or a shaped body with a laser beam.

[0002] Using selective laser melting, laser sintering, or laser cladding, shaped objects such as machine parts, tools, prostheses, jewelry, etc., can be manufactured or processed according to geometric description data of the respective shaped objects, for example, by layer-by-layer construction from a metallic or ceramic material powder or a plastic powder. In the manufacturing process, the material powder is heated by a focused laser beam in a predefined area corresponding to a selected cross-sectional region of the shaped object model, so that the material powder is melted in the irradiated areas to form cohesive, solidified sections. A protective gas can prevent oxidation during the build-up process. After cooling, a material layer is formed that can be mechanically processed.

[0003] For the state of the art in the field of selective laser melting, reference is made, for example, to DE 10 2015 222 689 A1. Furthermore, a laser machine tool of the type mentioned above is known, for example, from EP 2 052 845 A2. A machine tool for cladding is described, for example, in German patent application DE 10 2013 224 649 A1. German patent application DE 196 30 147 A1 describes a connection head for processing a workpiece using a laser beam, which has an automatic focusing lens changing mechanism designed as a turret.

[0004] The article “Laser Unit Makes Cladding Possible on Machining Centers” by Nowotny et al. in “MM Das Industriemagazin”, 17 / 2009, page 42 ff., describes a laser processing optic that is inserted into the milling spindle of a CNC machine via a steep taper. Welding material (material powder) is fed into the laser focal point through a powder nozzle. The workpiece can then be milled in the same machine.

[0005] Patent application US 2017 / 0136578A1 describes a generic machine for the layer-by-layer construction of a three-dimensional shaped body by melting a material powder. The material powder is guided to a working point by means of a powder nozzle attached to a laser processing head, where it is melted by a laser beam passing through the powder nozzle. The machine includes a powder nozzle exchange unit that replaces the powder nozzle attached to the laser processing head.

[0006] European patent application EP 2 062 679 A1 discloses a processing head for a laser processing machine, comprising a stationary part in the form of a laterally open housing that encloses a space for an interchangeable module. This module can be separated as a whole from the stationary part of the processing head without having to disassemble the stationary part into individual components. The interchangeable module includes a focusing optic that is movable coaxially to the laser beam and a measuring device for determining the position of the focusing optic.

[0007] Further generic laser processing heads or optics or optical arrangements for laser processing heads are disclosed, for example, in the following patent documents or utility models: US 2011 / 0 056 921 A1, DE 20 2009 012 924 U1, US 2014 / 0 285 900 A1, DE 10 2008 048 323 B3, DE 10 2014 210 838 A1, DE 100 40 921 A1, DE 10 2016 006 395 A1 and DE 10 2009 046 485 A1.

[0008] For example, US patent 2011 / 0 056 921 A1 discloses a laser processing head for a laser processing machine for processing a workpiece using a laser beam, comprising a focusing optic that focuses the laser beam; and a drive device for moving and / or adjusting the focusing optic, which is designed as a fluidic drive. At the point of impact of the laser beam, a gaseous stream can be introduced into an area adjacent to the focusing optic. The respective outlet opening is arranged at a predetermined distance from the focusing optic, so that the spatial arrangement of the outlet opening relative to the focusing optic cannot be changed when the focusing optic is moved or shifted.

[0009] Furthermore, US Patent 5,961,862 A discloses a deposition head as part of a laser machine tool. The deposition head delivers the laser beam and the powder to a deposition zone formed at the tip of the deposition head. A controller consisting of a digital computer directs the movement of the deposition zone along the toolpath and provides control signals to adjust the device functions, such as the speed at which the deposition head moves along the toolpath.

[0010] DE 199 44 484 C1 discloses an interchangeable device with two magazine positions, each equipped with a holding device for attaching a lens holder fitted with a focusing lens and an actuating device that interacts with a fixing device for the lens holder provided by the laser processing head. A further actuating device interacts with a second fastening device provided by the laser processing head for another functional element, for example a cutting nozzle, which is received from the same magazine position as the lens holder.

[0011] From DE 10 2015 218 030 A1, a coupling system for use on a spindle device of a machine tool is known. In this system, fastening bolts are used as plug-in connection elements, which can be fastened in corresponding plug-in connection elements designed as receptacles.

[0012] A laser machine tool is typically operated with a laser that provides a laser beam with an output power of several hundred to several thousand watts, usually operating in continuous wave (CW) mode. The energy transfer from the laser beam to the material powder is particularly crucial for the machining process. This transfer is influenced both by the absorption capacity of the material powder and by the intensity of the laser beam. Therefore, in addition to the absolute laser power, the beam diameter determines the melting process. The beam diameter of the laser beam is typically determined by the focal length of a focusing lens and by the beam diameter of the collimated laser beam in front of the focusing lens. The beam diameter of the collimated laser beam can be specifically determined by the focal length of a collimating lens.Thus, the beam diameter of the focused laser beam, or the waist of a Gaussian laser beam, can be adjusted by appropriately selecting the collimating lens, without changing the focal length of the focusing lens.

[0013] According to the prior art, essentially two types of machines for processing workpieces and / or producing shaped parts by selectively solidifying material powder into contiguous areas using a laser beam, in particular by selective laser melting or selective laser sintering, are known. The machine types differ, among other things, in the way the material powder is supplied. In a first machine type, a powder bed is built up layer by layer. In a second machine type, the material powder is supplied at the processing location by means of a powder nozzle. The present invention relates in particular to machines in which the laser beam is supplied by means of a laser processing head.

[0014] The mechanical setup for moving the laser processing head and / or the workpiece can be similar to that of a conventional five-axis machining center, except that the laser processing head replaces a mechanical tool. For several years now, machine tools have also been available that allow both laser processing and machining, for example with a milling tool. In such hybrid machining centers, the laser processing head can, for example, be attached to the tool spindle mount.

[0015] The laser processing head can include a variety of optical components for manipulating the laser beam, such as collimating, focusing, positioning, monitoring, switching, and / or modulating the laser beam's power. It has proven advantageous to combine as many components as possible into a pre-assembled, replaceable optical module that can be detachably attached to the machine using suitable means. This simplifies and accelerates the maintenance of a laser machine tool, allowing for more efficient machine operation by reducing downtime. The powder nozzle is typically attached to the laser processing head.

[0016] The present invention is based on the objective of providing a laser processing head, improved compared to the prior art, for a machine for processing workpieces and / or for producing shaped bodies by selectively solidifying material powder into contiguous areas using a laser beam. This objective is achieved by the laser processing head according to claim 1.

[0017] The laser processing head comprises an optical module and a focusing module with a cylindrical carrier housing, which is arranged in a correspondingly shaped cylindrical recess in the optical module.

[0018] In particular, the focusing lens module and focusing lens can be automatically changed during a processing operation, allowing the diameter of the laser beam at the working point, and consequently the intensity of the laser beam at the working point, to be automatically adjusted during the process. Because the focusing lens module features a detachable mounting mechanism, changing the focusing lens can be integrated into the processing operation without requiring any manual steps. The working point of the laser beam typically corresponds to the focal point of the laser beam focused by the focusing lens.

[0019] The laser processing head includes, in particular, a detachably mounted optical module in or on which the optical components for collimating and focusing the laser beam are arranged or can be attached. The focusing lens module can be attached to the optical module. A collimating lens arranged in the optical module serves to collimate a laser beam coupled divergently into the optical module. For example, the laser beam can be coupled into the optical module by means of an optical fiber. The optical module can therefore include means for connecting an optical fiber, in particular a fiber coupler. Since an optical fiber can transmit laser light over many meters, it is possible to place the laser in a protected location remote from the process chamber. The distance between the collimating lens and the end of the optical fiber corresponds approximately to the focal length of the collimating lens.The collimated laser beam can be focused to a focal point by the focusing lens module attached to the optical module using a focusing lens. The laser beam thus exits the optical module as a focused beam.

[0020] Optical components of laser machine tools can be subject to increased wear due to the relatively high laser power. Furthermore, particularly in hybrid machines capable of both laser processing and machining, optical components can become contaminated by coolant, dust, chips, and other particles. Material powder can also contribute to contamination. Dirt particles deposited on an optical component can lead to significant heat buildup, especially at high laser power, and thus damage the component. Therefore, it is desirable for optical components to be replaceable quickly and easily in case of damage or contamination. This is achieved, in part, by allowing the entire optical module to be detachably mounted as a pre-assembled unit on an actuator axis, thus facilitating easy replacement.On the other hand, interchangeable optical components allow for quick changes without removing the entire optical module. For example, the collimation lens changer enables a quick, automatic change of the collimation lens without requiring the replacement of the entire collimation changer or optical module.

[0021] The optical components arranged in or on the optical module can each be detachably mounted in or on the housing of the optical module. This allows for automatic replacement of the optical components during machine operation. Conversely, an optical module requiring maintenance can be restored to operational condition by replacing individual optical components. For example, the collimation changer can be detachably mounted in the housing of the optical module as a replaceable module and thus be exchanged during maintenance of the optical module.

[0022] Advantageous training and further education programs, which can be used individually or in combination, are the subject of dependent claims.

[0023] The focusing lens module can be connected to the optical module via at least two clamping bolts. The optical module has corresponding receptacles for these clamping bolts. These receptacles are designed as hydraulically or pneumatically actuated, or spring-loaded, clamping mechanisms.

[0024] By providing means for attaching an automatically interchangeable focusing lens module, the focusing lens can be changed automatically. This lens can then be exchanged fully automatically during the manufacturing or machining process, similar to a tool in a machining center. The automated exchange of the focusing and collimating lenses allows the beam diameter of the laser beam at focus to be adjusted within a wide range, depending on the requirements. The clamping bolts allow for quick and secure attachment of the focusing lens module to the optical module. Furthermore, the clamping bolts ensure that the focusing lens module can be attached to the optical module with high positional accuracy.

[0025] The focusing lens module comprises a cylindrical carrier housing with a circular cross-section, made, for example, of a metal or a metal alloy. The focusing lens is arranged within the carrier housing. Preferably, the focusing lens can be detachably mounted in the carrier housing of the focusing lens module, allowing for replacement of the focusing lens. For example, the carrier housing can have an internal thread. The focusing lens and / or the at least one protective glass can be attached to the carrier housing using suitable rings with an external thread.

[0026] The focal length of the focusing lens can be, for example, several hundred millimeters, in particular 100 mm, 200 mm, or 300 mm, or any focal length between 100 mm and 500 mm. The focusing lens can be a conventional converging lens. The focusing lens module preferably includes means for measuring the temperature of the focusing lens. It is further preferred that the focusing lens module includes means for cooling the focusing lens.

[0027] The focusing lens is preferably positioned axially within the housing, depending on its focal length. This ensures that the distance of the focal point from the laser processing head remains constant, regardless of the focusing lens used. This has the advantage that the laser processing head can always be guided at the same distance from the workpiece. Therefore, the machine control system does not need to perform any distance correction after changing the focusing lens focal length.

[0028] The focusing lens module can include at least one protective glass to protect the focusing lens from contamination. The protective glass can also protect the focusing lens from mechanical damage. The protective glass is preferably detachably mounted in the carrier housing of the focusing lens module. If it becomes contaminated, the protective glass can be replaced. Preferably, a protective glass is arranged axially on both sides of the focusing lens within the carrier housing of the focusing lens module, so that the focusing lens is protected from contamination and mechanical damage from both sides.

[0029] The focusing lens module can include means for measuring the temperature of at least one protective glass and / or the focusing lens. This allows contamination of a protective glass or the focusing lens to be detected, for example, by a temperature increase. At least one thermocouple can be used as the means for measuring the temperature. The focusing lens module can have at least one interface for transmitting a temperature measurement signal from the focusing lens module to the machine. This interface can preferably be connected to a corresponding interface on the laser processing head or the optical module. The interfaces are preferably designed to connect automatically when the focusing lens module is attached. For example, a simple electrical contact or a plug connector can be used as the interface. Brief description of the characters

[0030] Further advantageous embodiments are described in more detail below with reference to an exemplary embodiment shown in the drawings, to which, however, the invention is not limited.

[0031] They show schematically: Fig. 1: a machine tool with an optical module for manufacturing or processing a shaped body or workpiece using laser radiation. Fig. 2: A perspective sectional view of an exemplary embodiment of an optical module. Fig. 3: another perspective sectional view of the in Fig. 2 shown embodiment of the optical module. Fig. 4: A perspective view of an embodiment of a machine tool for manufacturing or machining a shaped body or workpiece using laser radiation. Fig.5: A perspective view of a tool changer for a machine tool for manufacturing or machining a shaped body or workpiece using laser radiation. Fig. 6: (A) a partially cutaway perspective view and (B) a perspective view of an interchangeable powder nozzle. Fig. 7 An illustration of the operating principle of laser cladding. Fig. 8 (A) a perspective view of an interchangeable focusing lens module according to the invention, (B) and (C) sectional views of the interchangeable focusing lens module with different focal lengths of the focusing lens. Detailed description of the invention using an exemplary embodiment

[0032] In the following description of a preferred embodiment of the present invention, the same reference numerals denote identical or comparable components.

[0033] Fig.Figure 1 shows a schematic representation of a machine 1 for machining a workpiece 20 and / or for producing a shaped body 20 by selectively solidifying material powder into contiguous areas using laser radiation. The machine 1 has a machine frame 21 to which a workpiece table 20 and an optical module 2 are attached, respectively, via intermediate positioning axes 18 and 19. The positioning axes 18 and 19 can each have several translational (X, Y, Z) or rotational (φ, λ, θ) axes, which are adjustable according to a machine control. The design can be such, for example, that the optical module 2 is attached to the machine frame 21 via one, two, or three translational positioning axes 18 (X and / or Y and / or Z), while the workpiece table 20 is attached to the machine frame 21 via one, two, or three rotational positioning axes 19.Such a laser machine tool 1 typically has a (not shown) enclosed cabin in which, for example, a protective gas atmosphere can be created, and which shields the working area from contamination.

[0034] A workpiece can be detachably attached to the workpiece table 20 for machining. Alternatively, a shaped body can be built up layer by layer on the workpiece table 20 by selectively solidifying material powder.

[0035] Machine 1, for example, could be a five-axis laser machine tool for producing shaped parts by selectively solidifying material powder into contiguous areas using laser radiation. The optical module 2 is detachably attached to the positioning axes 18, allowing for quick and easy replacement when necessary, for example, for maintenance. In such a five-axis laser machine tool, the optical module 2 is attached to the machine frame 21 via three translational positioning axes 18 (X, Y, and Z), and the workpiece table 20 is arranged on the machine frame via two rotary axes.

[0036] An exemplary representation of a five-axis laser machine tool 1 for producing shaped bodies by selectively solidifying material powder into contiguous areas using laser radiation is shown in Fig. 4 shown. The illustrated embodiment essentially corresponds to the one in Fig.Figure 1 schematically depicts machine 1. The workpiece table 20 and the optical module 2 are arranged in a process chamber 22, which can be sealed gas-tight essentially by a process chamber door 23. A display 24 located outside the process chamber 22 serves as an interface between the user and the machine control. Measured values ​​and / or warning messages and / or control applications can be displayed on this display 24.

[0037] The machine tool 1 includes a tool changer 25, which can be moved laterally into the process chamber 22 by means of positioning axes 25a, 25b. A detailed view of the tool changer 25 is shown in Fig. Figure 5 shows that a variety of focusing lens modules 13 and a variety of powder nozzles 15 can be arranged on the tool changer 25. The tool changer 25 is shown in Figure 5. Fig.The tool changer 25 shown in Figure 5 has three storage positions for powder nozzles 15 with different axial lengths. The tool changer 25 also has a storage area for at least two focusing lens modules 13 with focusing lenses 14 of different focal lengths. The focusing lens modules 13 and the powder nozzles 15 can be moved into the process chamber 22 by means of two positioning axes 25a and 25b, respectively, so that they can be attached to the optical module 2. A method for changing the powder nozzles 15 and the focusing lens modules 13 is described below.

[0038] The tool changer 25 can be moved by means of the positioning axes 25a, 25b into a tool chamber that can be separated from the process chamber 22 by means of a movable partition. In the tool chamber, the focusing lens modules 13 and the powder nozzles 15 are protected from contamination, for example by material powder or welding fumes, when machining of the workpiece is carried out in the process chamber 22.

[0039] In Fig.Figure 2 shows an optical module 2, which is detachably mounted on an adjustment axis 18. The adjustment axis 18 is, for example, a translation axis movable in the Z-direction, which can be arranged on two further translation axes movable in the X- and Y-directions, so that the optical module 2 can be moved in all three spatial directions. The optical module 2 is mounted on the adjustment axis 18 such that the laser beam exits the optical module 2 vertically downwards (parallel to the direction of gravity, i.e., in the Z-direction). By moving the adjustment axes 18, a focus of the focused laser beam can thus be moved in three dimensions in space to process a workpiece or to build up a shaped object layer by layer. In this way, a shaped object can be built up layer by layer, similar to a 3D printer, by fusing material powder.

[0040] The optical module 2 has a housing 8 in which a multitude of optical components are arranged. The housing 8 serves both as a mechanical platform for arranging the optical components and as a means of protecting them from mechanical influences. A protective gas atmosphere can be created within the housing 8. For example, overpressure can prevent the ingress of particles and dirt into the housing.

[0041] A fiber coupler 10 is arranged at the top of the housing 8, through which a laser beam from an optical fiber can be coupled. By using an optical fiber, laser light from a laser beam source can be reliably guided to the optical module 2. The flexible optical fiber allows the optical module 2, and thus the laser beam, to be moved without having to move the laser beam source itself. Furthermore, an optical fiber can deliver a laser beam with a particularly uniform beam profile.

[0042] A high-power solid-state laser can be used as a laser beam source. This includes, for example, doped YAG lasers. In particular, a ytterbium-doped YAG disk laser with a wavelength of 1030 nm can serve as a laser beam source. Alternatively, a neodymium-doped YAG laser with a wavelength of 1064 nm can be used as a beam source. Solid-state lasers can provide laser beams with power levels ranging from a few watts to several thousand watts. This allows for sufficient laser power to be provided for various processing and manufacturing applications.

[0043] Directly below the fiber coupler 10, the collimation lens changer 3 is arranged in the housing 8 of the optical module 2. A collimation lens 4 with a first focal length of, for example, 80 mm is arranged in the collimation lens changer 3 such that the laser beam exiting the fiber is collimated to a diameter of approximately 36 mm. The collimation lens changer 3 can include further collimation lenses 4 with focal lengths of, for example, 50 mm, 60 mm, and / or 100 mm or more. This allows collimated laser beams with diameters between approximately 10 mm and 100 mm to be provided. Suitable types of converging lenses can be used as collimation lenses 4. The material, coating, and other lens properties can be selected depending on the laser wavelength and laser power used.

[0044] The collimated laser beam is directed by two deflecting mirrors 6, 7 arranged in the optical module 2 onto a focusing lens 14, which focuses the laser beam. The position or orientation of the deflecting mirrors 6, 7 is preferably adjustable, so that the beam path of the laser beam can be automatically adjusted. The correct adjustment of the laser beam can be monitored, for example, by the camera 9. In particular, the deflecting mirrors 6, 7 can be adjustable via the machine control system. For this purpose, the deflecting mirrors 6, 7 can each be arranged on adjustable holders that can be controlled by the machine control system via control signals. The optical module 2 can have suitable interfaces for detachably connecting signal lines for the machine control system.

[0045] The focal length of the focusing lens 14 can, for example, be between 50 mm and 500 mm. The focusing lens 14 is arranged in an automatically interchangeable focusing lens module 13, which can be attached to the optical module 2 via a mounting mechanism 11, 16. Thus, by changing the focusing lens module 13, the focal length of the focusing lens 14 can also be changed fully automatically.

[0046] Seven exemplary combinations of lens focal lengths for the collimating lens 4 and the focusing lens 14 are shown in Table 1. Table 1 also lists exemplary resulting values ​​for the diameters of the collimated laser beam and the focused laser beam for a fiber core diameter of 600 µm. The smaller the beam diameter, the higher the laser intensity. A small beam diameter of the focused laser beam results in a high laser beam intensity, so that a melting process generally takes less time, since more energy can be transferred to a smaller area. On the other hand, smaller structures can be produced with a smaller beam diameter at the focal point of the laser beam. A smaller beam diameter at the focal point can be achieved with the same focal length of the focusing lens by using a larger beam diameter of the collimated laser beam in front of the focusing lens.A larger beam diameter of the collimated laser beam has the advantage that the optical elements in optical module 2 are exposed to a lower laser intensity. This reduces the likelihood of damage to the optical elements, as they are, for example, heated less. Table 1: Seven exemplary combinations of collimating lens focal length and focusing lens focal length: Size Unit Example 1 Example 2 Example 3 Example 4 Example 5 Example 8 Example 7 Performance W 4000 4000 4000 4000 4000 4000 4000 Focal length of the collimation lens mm 50 60 80 100 60 80 100 Diameter of the collimated beam mm 5a 25b 36 45 25b 36 45 Focal length of the focusing lens mm 300 300 300 300 200 200 200 Diameter of the focused beam mm 3,6 3 2,3 1,8 2 1,5 1,2

[0047] An exemplary embodiment of the focusing lens module 13 is shown in Fig. 8A to C are shown. Fig. Figure 8A shows a perspective view of a focusing lens module 13 with a substantially cylindrical support housing, preferably made of a metal with the lowest possible coefficient of thermal expansion. As shown in the examples in Table 1, Fig. 8B a focusing lens module 13 with a focusing lens 14 having a focal length of 200 mm, and Fig.8C comprises a focusing lens module 13 with a focusing lens 14 having a focal length of 300 mm. The focusing lenses 14 of different focal lengths are arranged in the various focusing lens modules 13 such that the resulting focal point of the laser is always located at the same position.

[0048] Fastening means, for example two clamping bolts 16, are arranged at an upper edge of the focusing lens module 13. The fastening means 16 also serve to ensure the highest possible positioning accuracy of less than 1 mm. This is particularly important for the precise guidance of the laser beam through the powder nozzle and to the correct operating point. Should deviations nevertheless occur, these can be detected by the camera 9 and corrected by the deflecting mirrors 6, 7. The focusing lens module 13 has at least one protective glass 14a to protect the focusing lens 14 from contamination or damage. Preferably, as shown in the sectional drawings of the Fig. 8B and C show a protective glass 14a arranged on both sides of the focusing lens 14 in the focusing lens module 13 to protect the focusing lens 14 from contamination or mechanical impact from both sides.

[0049] The temperature of at least one protective glass 14a can be monitored by a sensor 13a. Fig. In 8B and C, only the temperature of the upper protective glass 14a, which is first struck by the laser beam, is monitored by a sensor 13a. A temperature-dependent resistor (NTC resistor) or a thermocouple can be used as the sensor. The thermocouple can, in particular, be a wire made of a platinum alloy. Similarly, the temperature of other optical components in the optical module 2, in particular the collimating lenses 4, the protective glasses of the collimating lenses 4, the deflecting mirrors 6, 7, and / or the focusing lens 14, can also be monitored.

[0050] An analog measurement signal generated by the temperature sensor 14a is transmitted via interfaces 13b on the focusing lens module 13 to signal lines in the optical module 2. From there, the measurement signal is output to a machine control unit and converted into a temperature value, so that the temperature of an optical component of the optical module 2 can be displayed in degrees Celsius. The measured temperature values ​​can be shown, for example, on the display 24. A temperature threshold can be stored in the machine control unit for each optical component. If the measured temperature of an optical component exceeds the stored threshold, a warning signal can be generated. The warning signal can be issued, for example, as a warning to a user. The warning can be displayed visually, for example, on the display 24 or by means of a warning light.Additionally or alternatively, the laser can be switched off to prevent damage to the optical component.

[0051] The interfaces 13b can also be used to signal to the machine control system that a focusing lens module 13 has been successfully attached. Similarly, the machine control system can detect that the focusing lens module 13 has been successfully detached and placed down when a signal transmitted via the interfaces 13b is interrupted.

[0052] An interchangeable powder nozzle 15 can be attached below the focusing lens module 13, which can be mounted on the optical module 2. An exemplary embodiment of the powder nozzle 15 is shown in Fig. 6A and Fig.Figure 6B illustrates this. Like the focusing lens module 13, the powder nozzle 15 has fastening means 16 that can be attached to the optical module 2 by means of corresponding receptacles 12. For example, several clamping bolts can be arranged on the powder nozzle 15 as fastening means 16. Such clamping bolts are also used in a similar manner for fastening tools in conventional machine tools. The receptacles 12 on the optical module 2 can clamp these clamping bolts for fastening the powder nozzle 15 via a hydraulic, pneumatic, or spring-loaded mechanism, so that the powder nozzle 15 is detachably attached to the optical module 2, whereby the same position of the powder nozzle 15 can always be achieved within a defined tolerance.

[0053] The in Fig. 2 and Fig.The powder nozzle 15 shown in Figure 6 has a flange 15a at its upper end, facing the optical module 2, on which the fastening means 16, for example two clamping bolts, are arranged. A substantially cylindrical central section of the powder nozzle 15 is arranged on the flange 15a. A substantially conical powder nozzle tip 15b is arranged at the lower end of the central section.

[0054] The flange 15a of the powder nozzle 15 is equipped with connections 15f and 15g, respectively, for supplying a coolant or material powder. The coolant connections 15f can, for example, be designed as quick-release couplings that automatically connect to the corresponding lines on the optical module 2 when the powder nozzle 15 is attached. The material powder inlets 15g can be simple openings with a sealing ring. When the powder nozzle 15 is attached to the optical module 2, the inlets with the sealing rings are pressed against corresponding outlets on the optical module, creating a gas-tight connection.

[0055] The inlets 15g for material powder are each connected to channels 15d for the material powder, which run through the powder nozzle 15 to the tip 15b of the powder nozzle 15. An annular gap 15c is formed in the tip 15b of the powder nozzle 15, the width of which can taper in the direction of flow to create a nozzle effect. The transition between the material powder channels 15d and the annular gap 15c is shaped such that a uniform distribution of the material powder is achieved. The flow of the material powder can therefore have the form of a cone aligned coaxially with the focal point of the laser beam, as illustrated in the figure. Fig. 7 indicated.

[0056] The powder nozzle tip 15b can be detachably attached to the powder nozzle 15, allowing it to be replaced, for example, if damaged or deformed by heat. In a multi-part design of the powder nozzle 15, the powder nozzle tip 15b can also be made of a different, more heat-resistant and / or harder material than the rest of the powder nozzle 15. Differently sized powder nozzle tips 15b can be used, for example, for different laser beam diameters. Accordingly, different powder nozzles 15 with differently sized powder nozzle tips 15b can be kept in the machine 1, so that the entire powder nozzle 15 can be replaced if necessary. The diameter of the lower opening of the powder nozzle tip 15b, facing the workpiece, can be, for example, 1 mm, 2 mm, or 3 to 4 mm.

[0057] The powder nozzle 15 has at least two couplings 15f for coolant, which are preferably designed as quick-release couplings. One coupling 15f serves as a connection for the coolant supply from the optical module 2, the other coupling 15f serves as a connection for the coolant return to the optical module 2. The coolant connections 15f are in flow communication with coolant channels 15e in the powder nozzle 15, which are shown in the partially cutaway view of the Fig. Figure 6A illustrates this. The coolant channels 15e can, for example, be arranged in a ring around the laser beam aperture to ensure uniform cooling of the powder nozzle 15.

[0058] Inside the flange 15a, a substantially cylindrical recess is formed for the focusing lens module 13. When the focusing lens module 13 and the powder nozzle 15 are attached to the optical module 2, the lower end of the focusing lens module 13 is located within the recess in the powder nozzle 15. The focusing lens module 13 and the powder nozzle 15 are thus arranged coaxially with each other and with the laser beam on the optical module 2.

[0059] The powder nozzle 15 has a very complex shape due to the numerous channels for coolant 15e and channels for material powder 15d, as well as its axially tapered opening towards the laser focal point. Such a complex shape can be produced, for example, by a laser cladding process in a machine 1 according to the invention. In order to carry out the manufacturing process of the powder nozzle 15 by laser cladding in the shortest possible time and with the greatest possible material savings, the essentially cylindrical central section of the powder nozzle 15 can, for example, be constructed with the thinnest possible wall thickness. To increase the mechanical strength of the powder nozzle 15, the wall can be reinforced by lamellae 15l. Similarly, the transition between the flange 15a and the central section of the powder nozzle 15 can be manufactured in a material-saving manner, for example, by using a profile as shown in Fig.The honeycomb structure shown in Figure 6B uses 15w, which offers high mechanical strength with low material consumption.

[0060] The flange 15a and the central section of the powder nozzle 15 can, for example, be made of aluminum. The diameter of the flange 15a can be approximately 150 mm to 170 mm, preferably 160 mm. The length of the powder nozzle 15 can be approximately 125 mm to 145 mm, preferably 135 mm. The diameter of the central section of the powder nozzle can be approximately 60 mm to 70 mm, preferably 67 mm. Preferably, the powder nozzle 15 can also be designed to be even more compact in order to reduce the risk of collisions with the workpiece.

[0061] Replacing the powder nozzle 15 can be carried out, for example, as described below. The partition between the process chamber 22 and the tool chamber located to the side of it is slid open. Using the positioning axis 25b, the lower part of the tool changer 25 with the powder nozzles 15 is moved into the process chamber 22. The positioning axes 18 move the optical module 2 to the position where the tool changer 25 with the multiple powder nozzles 15 is located. Unlike in [previous description], to place a powder nozzle 15 attached to the optical module 2, [further steps are required]. Fig. 4 and Fig. Figure 5 shows that a storage position of the tool changer 25 must be free. By opening the receptacles 12 on the optical module 2, the fastening means 16 of the powder nozzle 15 are released, so that the powder nozzle 15 is detached from the optical module 2 and can be placed in a free storage position of the tool changer 25.

[0062] The optical module 2 is then moved to a different position on the tool changer 25, where another powder nozzle 15, having a larger or smaller axial dimension, is located. The optical module 2 is then moved by means of the positioning axes 18 so that the fastening means 16 of the additional powder nozzle 15 engage in the receptacles 12 on the optical module 2. By closing the receptacles 12, the powder nozzle 15 can be attached to the optical module 2 and removed from the tool changer 25.

[0063] Automatic powder nozzle changing 15 is particularly useful when the focal length of the laser beam is changed by replacing the focusing lens 14. Since the powder nozzle 15 is intended to direct the material powder to the focal point of the laser beam, its axial length must be selected according to the laser beam's focal length. As listed in Table 1, the focal length of the focusing lens 14 can be, for example, 200 mm or 300 mm. Accordingly, the tool changer 25 of the machine 1 can be equipped with corresponding powder nozzles 15 that direct material powder to a focal point located, for example, 200 mm or 300 mm away from the focusing lens 14.

[0064] A material powder can be supplied to the operating point of the machine 1, i.e., in the immediate vicinity of the focal point of the laser beam, via the powder nozzle 15. For this purpose, the powder nozzle 15 has one or more channels through which the material powder is guided. When the powder nozzle 15 is attached to the optical module 2, a connection is established between the channels for the material powder and corresponding lines in the optical module 2. The powder nozzle 15 and the optical module 2 each have suitable interfaces for connecting the channels and the lines. Furthermore, the powder nozzle 15 has one or more cooling channels in which a fluid coolant, in particular water, can circulate to cool the powder nozzle 15. The optical module 2 has corresponding lines for supplying and removing the coolant, as well as interfaces for connecting the lines to the cooling channels of the powder nozzle 15.

[0065] Furthermore, the powder nozzle 15 can supply a protective gas to the operating point of the machine 1, so that undesirable reactions during the melting of the material powder at the focal point of the laser beam can be largely suppressed. The protective gas serves primarily to displace oxygen from the air. Inert gases such as argon can be used as protective gases. The optical module 2 has corresponding lines for supplying the protective gas. The protective gas can also be supplied together with the material powder as a carrier gas. Thus, the protective gas serves both to prevent a reaction with atmospheric oxygen and to convey the material powder.

[0066] During the automatic exchange of the powder nozzle 15, the cooling lines of the optical module 2 are automatically connected or disconnected from the cooling channels of the powder nozzle 15 via the corresponding interfaces. Similarly, the lines for material powder in the optical module 2 are also automatically connected or disconnected from the material powder channels in the powder nozzle 15 via the corresponding interfaces. The interfaces for the lines and channels can be designed to be detachable and, for example, controlled hydraulically or pneumatically.

[0067] An automatic change of the focusing lens module 13 can be performed in a similar manner to the automatic change of the powder nozzle 15. In this process, the upper part of the tool changer 25, including the focusing lens modules 13, is moved into the process chamber 22 by means of the positioning axis 25a. However, to change the focusing lens module 13, a powder nozzle 15 attached to the optical module 2 must first be detached. This is done as described above by placing the powder nozzle 15 in a free storage position of the tool changer 25. The positioning axes 18 then move the optical module 2 to a position where the tool changer 25, with its multiple focusing lens modules 13, is located. The focusing lens module 13, which is attached to the optical module 2, can be released by opening the receptacles 11 on the optical module 2, so that the focusing lens module 13 can be detached from the optical module 2 and placed at a free storage position of the tool changer 25.Subsequently, another focusing lens module 13 can be attached to the optical module 2. For this purpose, the optical module 2 is moved so that the fastening elements 16 of the focusing lens module 13 engage in the receptacles 11 on the optical module 2. The receptacles 11 on the optical module 2 can then clamp the fastening elements 16, for example, via a hydraulic, pneumatic, or spring-loaded mechanism, to secure the focusing lens module 13 to the optical module 2. The tool changer 25 can then be moved back into the detachable tool chamber, and machining of the workpiece can be started or continued.

[0068] The required travel distances of the positioning axes 18, 25a, and 25b can be stored in a memory of the machine control, enabling fully automatic exchange of the focusing lens module 13 or the powder nozzle 15. This exchange can therefore be integrated into a machining process. As a result, a suitable combination of focusing lens 14 and powder nozzle 15 can be attached to the optical module 2 for each machining operation.

[0069] The first deflecting mirror 6 has means for cooling and monitoring its temperature. The second deflecting mirror 7 is a dichroic mirror, which also has means for cooling and monitoring its temperature. For the wavelength of the laser beam, which lies, for example, in the infrared spectral range, the dichroic mirror 7 is reflective. For visible light, however, the dichroic mirror can be transparent. A camera 9 for monitoring the manufacturing process can be positioned behind the dichroic mirror 7. The camera 9 is positioned with its view along the laser beam through the dichroic mirror and, via the focusing lens 14, onto the focal point of the laser beam. Thus, the camera 9 can be used to monitor the working point on the workpiece or the molded part to be manufactured.

[0070] The optical module 2 has interfaces for receiving control signals from a machine control system. These control signals can, for example, cause the collimation lens changer 3 to perform a collimation lens change. Furthermore, the measured temperatures of the collimation lenses 4, the deflecting mirrors 6, 7, or the other optical components can be transmitted to the machine control system via these interfaces.

[0071] The operating principle of laser cladding is explained using the following examples: Fig. 7 illustrated. Fig.Figure 7 shows the tip 30 of a powder nozzle 15 near a workpiece W to be processed. A focused laser beam L is coaxial with the powder nozzle 15 and is focused on a working point on the workpiece W. The material powder P is guided coaxially to the laser beam L through the powder nozzle 15 to the focal point of the laser beam L on the workpiece W. A shielding or carrier gas G also flows through the powder nozzle 15 and transports the material powder P. The shielding gas G, for example argon, also serves to prevent unwanted reactions of the heated material powder P or the workpiece W with atmospheric oxygen.

[0072] The features disclosed in the foregoing description, the claims and the drawings may be important for the realization of the invention in its various embodiments, both individually and in any combination. Reference symbol list 1 laser machine tool 2 Optical module 3 collimation lens changers 4 Collimation lens 6 first deflecting mirror 7. Second deflecting mirror (dichroic mirror) 8 cases 9 Camera 10 fiber optic couplers 11 Interface for focusing lens 12 Interface for powder nozzle 13 Focusing lens module 13a Thermocouple 13b Thermocouple interface 14 Focusing lens 14a Protective glass 15 powder nozzle 15a Powder nozzle flange 15b Powder nozzle tip 15c annular gap 15d Material powder channel 15e Cooling channel 15f Coolant coupling 15g material powder inlet 15l slats 15w honeycomb structure 16 clamping bolts 17. Laser beam path 18 axes of adjustment of the tool 19 axes of the workpiece table 20 Workpiece table 21 machine frames 22nd Tribunal 23 Process room door 24" Display 25 tool changers 25a Positioning axis of the focusing lens changer 25b Adjustment axis of the powder nozzle changer L laser beam W workpiece P workpiece powder G Shielding gas and / or carrier gas

Claims

[1] Laser processing head for a machine (1) for processing workpieces and / or for producing shaped bodies by locally solidifying material powder into coherent regions by means of a laser beam, comprising an optical module (2) and a focusing module (13), wherein the focusing module (13) comprises: a cylindrical support housing arranged in a correspondingly shaped cylindrical recess in the optical module (2); a focusing optic (14); and Fastening means (16) for detachably fastening the focusing module (13) to the optics module (2), wherein the fastening means (16) are two clamping bolts arranged on an upper edge of the focusing module (13); wherein the optical module (2) has receptacles (11) with a hydraulic, pneumatic or spring-loaded mechanism for clamping the clamping bolts, which are arranged on an upper edge of the cylindrical recess; wherein the mechanism is configured to open and close automatically to enable automatic changing of the focusing module (13). [2] Laser processing head according to claim 1, wherein the focusing module (13) comprises means for cooling the focusing optics (14). [3] Laser processing head according to one of the preceding claims, wherein the focusing module (13) comprises means for measuring the temperature of the focusing optics (14). [4] Laser processing head according to one of the preceding claims, wherein the focusing module (13) has at least one protective glass (14a) for protecting the focusing optics (14) from contamination. [5] Laser processing head (2) according to claim 4, wherein the focusing module (13) comprises means (13a) for measuring the temperature of the at least one protective glass (14a). [6] Laser processing head (2) according to claim 3 and / or 5, wherein the focusing module (13) has at least one interface (13b) for transmitting a measured temperature signal from the means (13a) for measuring the temperature of the focusing optics (14) and / or the at least one protective glass (14a) to the machine (1). [7] Laser processing head according to one of the preceding claims, wherein the focusing optics (14) are positioned in the carrier housing in the axial direction depending on their focal length. [8] Laser processing head according to one of the preceding claims, wherein the focusing optics (14) are detachably fastened in the focusing module (13). [9] Machine (1) for machining workpieces and / or for producing shaped bodies by locally solidifying material powder into coherent areas by means of a laser beam, characterized by that the machine has a laser processing head according to at least one of claims 1 to 8.

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