Laser processing head and laser cutting machine

Abstract

A laser processing head (20) for directing a laser beam (LB), wherein the laser processing head (20) comprises the following: - a housing (60) having an interior for the passage of a laser beam (LB) along an optical axis (A) from an inlet (61a) to an outlet (61b); - at least one reflector (70 or 74) arranged inside the housing (60) and reflecting the laser beam (20) along the optical axis (A) between the inlet (61a) and the outlet (61b); - a lens element (80) arranged inside the housing (60), wherein the lens element (80) is movable along the optical axis (A) and is configured to adjust a focal length of the laser beam (LB); - one or more collection areas (110a-c) arranged and configured inside to collect contamination directed by a purge gas; - one or more nozzles (106a-d) configured to direct the purge gas over one or more of the at least one reflector (70 or 74) and the lens element (80), wherein the one or more nozzles (106a-d) comprise a first of the one or more nozzles (106a-d) arranged adjacent to an end of the lens element (80) and configured to direct the purge gas over a first side of the lens element (80); and wherein the one or more collecting areas (110a-c) comprise a first of the one or more collecting areas (110a-c) arranged inside adjacent to the lens element (80) and downstream of the first nozzle.

Description

Field of the invention

[0001] The subject matter of the present invention relates to a laser processing head and a laser cutting machine comprising such a laser processing head. Brief description of the state of the art

[0002] A laser processing head, such as one used for cutting or material processing, can deliver a high-power laser beam of 10 kW or even up to 30 kW. Depending on the operating conditions, the high-power head can be exposed to contaminants that can damage the lenses and other optics within the head, impairing its performance. For example, assembly and repairs to the laser processing head can introduce contaminants into the head. Furthermore, emissions can occur during welding and cutting of workpieces, depositing contaminants on the optical surfaces. Contaminants not only limit the performance of the optical systems but can also damage or even destroy the laser optics.

[0003] Internal and external contamination is probably the most serious source of potential optics failure. All assembly processes carry the risk of contamination, so a solution must be found to reduce its impact and damage. Current state-of-the-art technology aims to reduce the number of components required to assemble a machining head, the number of screw connections that can generate contamination, and to assemble the optics for the machining head in clean rooms. However, the formation of contamination cannot be completely avoided.

[0004] The published German patent application DE 10 2016 117 040 A1 discloses a laser processing system comprising a laser oscillator configured to oscillate a laser beam; a laser beam path that guides the laser beam from the laser oscillator to an object to be processed; an impure gas adsorbent for adsorbing an impure gas that influences propagation of the laser beam; and an exposure function part configured to expose the impure gas adsorbent in the laser beam path.

[0005] Published Japanese Patent Application JP 2021-70055 A discloses a laser processing apparatus with high usability that ensures processing quality, extends the service life of an air supply mechanism for removing dust adhering to an optical component by reducing the risk of failure, and immediately stops the processing operation when processing quality cannot be maintained due to dust adhering to an optical component and then automatically resumes the processing operation. A laser processing apparatus according to this document includes a light detector for receiving and converting a portion of a laser beam passing through at least one of the optical components into an electrical signal; a nozzle for blowing gas against the at least one optical component; and a gas supply mechanism for supplying gas to the nozzle.A control unit performs control to stop the processing operation when an electrical signal from the light detector is less than a threshold value, to blow gas from the nozzle against the at least one optical component, and to resume the processing operation after completion of the blowing when an electrical signal from the light detector exceeds the threshold value.

[0006] The published German patent application DE 10 2016 117 039 A1 discloses a laser processing system comprising a laser oscillator configured to oscillate a laser beam; a laser beam path that guides the laser beam from the laser oscillator to an object to be processed; an oxygen sensor for detecting oxygen and an impurity gas sensor for detecting an impurity gas that affects the propagation of the laser beam, which are installed in the laser beam path; and an impurity gas sensor output value correction unit configured to correct an output value of the impurity gas sensor based on an output value of the oxygen sensor.

[0007] Published Japanese patent application JP 2005-81399 A discloses that, in the event that a condenser in a laser processing head burns out during laser processing, the smoke generated during the burnout in the laser processing head on the laser input side of the condenser is detected by a lens burn detector. In response to the lens burn detection signal, the emission of the laser beam passing through the condenser is interrupted by a laser shutoff device, a cooling unit for cooling the condenser is stopped, and then the smoke inside the laser processing head on the laser input side is exhausted by a gas exhaust unit.

[0008] The subject matter of the present disclosure is directed to overcoming or at least reducing the effects of one or more of the problems set forth above. Brief description of the invention

[0009] A laser processing head disclosed herein is used to direct a laser beam. The head includes a housing having an interior for passing a laser beam along an optical axis from an inlet to an outlet; at least one reflector disposed inside the housing and reflecting the laser beam along the optical axis between the inlet and the outlet; a lens element disposed inside the housing, the lens element being movable along the optical axis and configured to adjust a focal length of the laser beam; one or more collection regions disposed inside and configured to collect contaminants directed by a purge gas;one or more nozzles configured to direct the purge gas over one or more of the at least one reflector and the lens element, wherein the one or more nozzles comprise a first of the one or more nozzles disposed adjacent to an end of the lens element and configured to direct the purge gas over a first side of the lens element; and wherein the one or more collection regions comprise a first of the one or more collection regions disposed internally adjacent the lens element and downstream of the first nozzle.

[0010] Furthermore, a laser processing head for directing a laser beam is disclosed, comprising: a housing having an interior for the passage of a laser beam along an optical axis from an inlet to an outlet; a first reflector disposed inside the housing and reflecting the laser beam along the optical axis from the inlet; a second reflector disposed inside the housing and reflecting the laser beam from the first reflector along the optical axis toward the outlet; a lens element disposed inside the housing between the first and second reflectors, the lens element being movable along the optical axis and configured to adjust a focal length of the laser beam; one or more nozzles configured to direct purge gas over one or more of the first reflector, the second reflector, and the lens element;and one or more collection regions disposed within and configured to collect contamination directed by the purge gas; at least one of: (i) a source disposed in communication with the one or more nozzles and configured to direct the purge gas to the one or more nozzles, and (ii) an outlet disposed in communication with the housing and configured to draw the purge gas from the housing; and a control unit configured to operate at least one of the source and the outlet, wherein at least one of the first and second reflectors is movable within the housing; and wherein the control unit is configured to move at least one of: (a) the lens element and (b) the at least one of the first and second reflectors with respect to the operation of the at least one of the source and the outlet.

[0011] A laser cutting machine disclosed herein is used with a laser source to cut a workpiece. The machine comprises a laser processing head that receives laser radiation from the laser source, the laser processing head including at least one housing having an interior for the passage of laser radiation along an optical axis from an inlet to an outlet. The machine further comprises at least one reflector disposed inside the housing and reflecting the laser radiation along the optical axis between the inlet and the outlet; a lens element disposed inside the housing, the lens element being movable along the optical axis and configured to adjust a focal length of the laser radiation beyond the outlet; one or more nozzles configured to direct purge gas over one or more of the at least one reflector and the lens element;and one or more collection areas disposed internally and configured to collect contamination directed by the purge gas; and an actuator supporting the laser processing head and configured to manipulate the laser processing head with respect to the workpiece; at least one of: (i) a source disposed in communication with the one or more nozzles and configured to direct the purge gas to the one or more nozzles, and (ii) a drain disposed in communication with the housing and configured to draw the purge gas from the housing; and a control unit configured to operate at least one of the source and the drain, wherein at least one of the first and second reflectors is movable within the housing;and wherein the control unit is configured to move at least one of: (a) the lens element and (b) the at least one of the first and second reflectors relative to the operation of at least one of the source and the drain.;

[0012] The foregoing summary is not intended to summarize every possible embodiment or aspect of the present disclosure. Short description of the characters Fig. 1 illustrates a laser delivery system according to the present disclosure. Fig. 2 illustrates a perspective view of an example of a laser processing head according to the present disclosure. Fig. 3 illustrates a laser processing head of the present disclosure in more detail. Fig. 4 illustrates another laser processing head of the present disclosure in more detail. Detailed description of the invention

[0013] The technical problem of the invention is solved by the features of the independent claims. Further embodiments are specified in the dependent claims.

[0014] Fig. Figure 1 illustrates a laser delivery system 10 according to the present disclosure. A laser source 12 generates high-power laser light that propagates along a fiber optic cable 14 to a laser processing head 20. The laser source 12 can be any suitable multimode or single-mode laser, depending on the required laser power.

[0015] The laser processing head 20 can be moved relative to a workpiece WP and / or the workpiece WP can be moved relative thereto. For example, the laser processing head 20 can be moved by a gantry system, a robotic arm, or other device 16 used in the art. Internally, the laser processing head 20 includes optics to focus the laser energy in a laser beam LB onto the workpiece WP, and the laser processing head 20 can be used for cutting, soldering, welding, additive manufacturing, or other laser processes. A control unit 30 can be used to control the operation of components of the system 10, such as in a manner discussed below.

[0016] In a particular implementation, the laser delivery system 10 can be used for a flatbed laser cutting machine. Generally, the workpiece WP is supported on a flatbed of the machine, and the laser processing head 20 is manipulated above the workpiece WP by a gantry system 16 to perform two-dimensional cuts, trims, or holes in the workpiece WP. Typically, the head 20 is manipulated primarily in a horizontal plane above the workpiece and can be raised and lowered to move away from the workpiece. Of course, the system 10 can also be used in other implementations, such as bevel cutting, or mounted on an industrial robot.

[0017] Fig. Figure 2 illustrates a laser processing head 50 according to the present disclosure. The laser processing head 50 includes a housing 60 for internal optics 55. A feed fiber 24, for example, from a fiber optic cable connected to a cable receptacle 22, guides the laser light into the interior 62 of the head 60. Cover slides 64, 66 arranged in the housing 60 can protect the internal optics 55 from contamination, thus creating a clean room in the interior 62 in which a first reflector 70, a lens element 80, and a second reflector 74 are arranged.

[0018] During operation, the laser input (e.g., the high-power laser feed fiber 24 from the cable receptacle 22) in the head 60 emits a high-power laser beam LB inside the housing 62. The laser beam LB passes through the top cover slide 64 and is reflected by the first reflector 70. The reflected laser beam then passes through the lens element 80, which converges the laser light. The second reflector 74 then reflects the converged light of the laser beam to the focal point FB for impingement on a workpiece WP, so that the focused laser beam LB emitted from the housing 60 can fulfill the purposes of the laser process, such as welding, additive manufacturing, cutting, etc. Both the first reflector 70 and the second reflector 74 can be partially transmissive, allowing process observations to be made. Both reflectors 70, 74 can also be used to monitor the laser or the internal condition of the head.Additionally or alternatively, the reflectors 70 and / or 74 can be tilted to change the lateral arrangement of the focal point FP on the workpiece WP.

[0019] In general, the housing 60 may include an array of modules 63a-c that are assembled to form the housing 60. Multiple modules are interchangeable and can be secured together using various mounting hardware such as mounting screws, precision threaded holes, flanges, etc. Each of the modules 63a-c defines an internal passage for transmitting the laser beam LB from the delivery fiber 24 along an optical axis of the head 50 to the process zone.

[0020] Preferably, the head 50 has reduced complexity and has few optical surfaces. A conventional laser processing head, such as that used for a cutting head, typically has many optical elements that are expensive and require maintenance, and the conventional head can be very sensitive to contamination due to the many optical surfaces used. As can be seen, the optics 55 of the disclosed laser processing head 50 uses few optical components 70, 74, 80.

[0021] In addition, the head 50 includes only a few modules 63a-c that can be connected together to form the housing 60. These modules can include an input module 63a for the cable receptacle 22 and the feed fiber 24; an optics module 63b containing the lens element 80, an actuator or drive 86, reflectors or mirrors 70, 74, etc.; and an output module 63b. Alternatively, the reflectors 70 and 74 can also be integral with the input module 63a and the output module 63c, respectively. Extension points 52, 54 behind the reflectors 70 and 74 can be used for process monitoring and cooling.Other possible modules for the head 20 may include any number of interface or adapter modules (not shown), a process monitoring module (not shown) to which vision sensors may be attached, a cover slide module (not shown) having the replaceable cover slides 64, 66, and the like, although features for all of these may be combined with the other modules 63a-c.

[0022] The laser processing head 50 provides minimal Z-axis displacement of the focal point FP for very high laser powers (> 20 kW). The working distance of the head 50 is preferably large so that a large distance SO can be maintained between the process cover slider 66 and the laser process on the workpiece WP to minimize contamination. In an exemplary implementation, the laser processing head 50 may have a focal length of approximately 300 mm, a numerical aperture of approximately 150 mrad, and a magnification M of greater than 1.5. The Z-axis displacement (Delta Z) for the focal point FP may be greater than 40 mm and even greater than 60 mm.

[0023] Overall, the laser processing head 50 is resistant to contamination. As discussed in more detail below, the head 50 further includes a cross-jet assembly (not shown) for providing cross-jets of gas to manage contamination within the housing 62. Additionally, the head 50 includes a primary lens element 80, apart from the interchangeable optics of the cover slides 64, 66. Generally, the lens element 80 may include only one lens, but the element 80 may include a group of two or more lenses, as appropriate. In any event, a single, sole, or single-lens element 80 is provided within the head 50, as opposed to multiple elements for collimating, focusing, and the like.

[0024] The optical axis A of the lens element 80 is aligned horizontally in an orientation suitable for a 2D flatbed cutting machine. The head 50 can also be tilted to enable bevel cutting. As shown here, the cable receptacle 22 can extend vertically on the housing 60 for vertical connection to a laser cable (14). To guide the laser beam LB from the feed fiber 24 through the lens element 80 and to the workpiece WP, the head 50 has two reflectors 70, 74. One reflector 70 or 74 can be used for lateral adjustment of the focus position, and both reflectors 70, 74 can be used for process monitor connections at the extension points 52, 54. In an alternative configuration, the cable receptacle 22 extends horizontally on the housing 60 to be connected horizontally to a laser cable (14) so ​​that only one reflector 74 is required to direct the laser beam LB for flatbed cutting.

[0025] The single lens element 80 is preferably made of either fused silica or a high-performance compatible material with high thermal conductivity, such as ZnS or sapphire, which has advantages in terms of contamination resistance. The lens element 80 is movable along the optical axis A to create a Z-movement of the focal point FP. Due to the horizontal orientation of the lens element 80, contamination tends to fall downward due to gravity. Components 84, 86 that can generate particles, such as actuators, drives, joints, bearings, and the like, are located below the lens element 80 or are arranged on the underside of the lens element 80. The components 84, 86 can also be separated from the optical clean space in the head 50 using sealing features (not shown).

[0026] With the understanding of the laser processing head 50 with its internal optics 55 in the housing 60, the discussion now turns to further details of the present disclosure.

[0027] As in Fig. 3, a laser processing head 50 for directing the laser beam LB is shown in more detail. As schematically shown, the head 50 includes a housing 60, a first reflector 70, a lens element 80, and a second reflector 74. The housing 60 has an interior space 62 for the passage of the laser beam LB along an optical axis A from an inlet 61a to an outlet 61b of the housing 60. In general, the inlet 61a may accommodate a laser source (22, 24: Fig. 2) and a cover slider (64: Fig. 2) to separate a clean room for the optics 55 from any connections or the like. Likewise, the outlet 61b includes a cover slide (66: Fig. 2) to separate the optics 55 from the processing area of ​​the laser beam LB on the workpiece.

[0028] The first reflector 70 is arranged inside the interior 62 of the housing 60 and deflects the laser beam LB from the inlet 61a to the lens element 80. As shown, the optical axis A is deflected or rotated by the first reflector 70 from a longitudinal (vertical) direction in the Z-axis to a lateral (horizontal) direction in the XY plane. The second reflector 74, in turn, deflects the laser beam LB from the lateral direction to the longitudinal (vertical) direction toward the outlet 61b. The lens element 80 arranged between the reflectors 70, 74 can be moved along the lateral direction to change the magnification of the head 50, which adjusts a focal length of the laser beam LB beyond the outlet 61b, as mentioned above.In general, and as illustrated, the lens element 80 may include a lens 82 (or a group of lenses) disposed within a mount or mechanical structure 84 that may be moved by one or more actuators or drives 86.

[0029] A cross-jet assembly 100 is disposed on the head 50 to direct purge gas toward the internal optics 55 of the head 50 and remove contaminants that may interfere with operation. The cross-jet assembly 100 includes a gas source 102, which may include a compressor, a pump, a gas source, a filter, etc. One or more nozzles 106a-d, connected to one or more supply lines 104, are configured to direct purge gas over one or more of the first reflector 70, the second reflector 74, and the lens element 80 within the interior 62 of the housing 60. Generally, the gas source 102 may be spaced apart from the housing 60, and the supply lines 104 may extend outside and / or inside the housing 60.Likewise, the nozzles 106a-d can be arranged on the outside and / or on the inside of the housing 60, but the nozzles 106a-d are directed with their outlets for the gas in the interior 62 towards the optical components 70, 74, 80.

[0030] To collect the contaminants, one or more collection areas 110a-c are disposed within the interior 62 opposite the one or more nozzles 106a-d. As discussed below, these collection areas 110a-c may have filters 112a-c, ports 116, membranes, or check valves associated with them to prevent contaminated air from flowing back through the membranes / filters during temperature / pressure equalization.

[0031] The purge gas removes particles and other contaminants from the surfaces of these components 70, 74, 80 by flushing them away from the surfaces. It is understood that contaminants may enter the housing 60 during assembly or repair and become dislodged due to vibration and movement. An internal moving component within the housing 60 may also generate contamination. Due to the high power of the laser beam LB, the contamination may be detrimental to the head 50 and its operation, so the assembly 100 is used to mitigate its impact.

[0032] As described in the detailed configuration of Fig. 3, a first nozzle 106a is disposed adjacent one end of the first reflector 70 and configured to direct the purge gas over the first reflector 70. A collection region 110a is disposed within the interior 62 adjacent an opposite end of this first reflector 70 to collect any contaminants. In other words, the collection region 110a is located downstream of the first nozzle 106a to collect any contaminants swept away by the first reflector 70. A second nozzle 106b is disposed adjacent one end of the second reflector 74 and configured to direct the purge gas over the second reflector 74 so that a second collection region 110b within the interior 62 adjacent an opposite end of the second reflector 74 can collect any contaminants.In other words, the second collection region 110b is located downstream of the second nozzle 106a to collect any contaminants swept away by the second reflector 74. A set of nozzles 106c-d is disposed adjacent to one end of the lens element 80 and configured to direct the purge gas over the opposite surfaces or sides of the lens 82. A collection region 110c, located within the interior 62 adjacent to an opposite end of the lens element 80, can collect any contaminants. In other words, the collection region 110c is located downstream of the nozzle 106c-d to collect any contaminants swept away by the lens element 80.

[0033] Depending on the implementation, more or fewer nozzles 106a-d and collection areas 110a-c can be used. Likewise, the collection areas 110a-c can be arranged arbitrarily. For example, the collection area 110b can be Fig. 3 may include a plurality of opposing regions around the interior of the housing 62, or the collection region 110b may be an annular region disposed around the inner periphery of the interior of the housing 62.

[0034] The gas source 102 and the nozzles 106a-d can provide specific flow rates and pressures to effectively flush contaminants away from the optics 55. The nozzles 106a-d can take any number of forms. For example, the nozzles 106a-d can include jet nozzles. The nozzles 106a-d can include Laval nozzles, Laval fan nozzles, or convergent-divergent nozzles to provide uniform flushing of larger areas and a consistent flow of the purge gas over the surfaces of the optics 55. Because certain nozzles can generate significant noise when passing large volumes of purge gas through the head 50, the nozzles 106a-d can include noise isolation features. Additionally, the nozzles 106a-d can include needle valves or other elements to control the flow rate per nozzle 106a-d. The nozzles 106a-d control the distribution and shaping of the purge gas flowing past the optics.The outlet ports 116 could also include valves and flow control elements. In addition, baffles, cross-sectional areas, and other features can be incorporated into the interior 62 of the housing 60 to control the distribution and shaping of the purge gas.

[0035] The collection regions 110a-c may include particulate filters 112a-c configured to allow the purge gas to pass through, but configured to trap contaminants at or near the collection regions 110a-c. The filters 112a-c may include a metal wire mesh filter, and the filters 112a-c may be replaceable. Furthermore, at least one opening 116 in the housing 110 may communicate with the interior 62. As illustrated, each of the collection regions 110a-c may have at least one port 116 associated with the region. The at least one port 116 may be an open port that allows both gas and contaminants to exit the interior of the housing 62. Furthermore, the opening 116 may include a membrane configured to allow the purge gas to exit the interior 62 after the gas has purged the optical elements 70, 74, 80.The membrane of the at least one outlet opening 116 allows gas to leave the optics 55, but prevents the ingress of contaminated air.

[0036] To assist in passing the purge gas through the filters 112a-c and capturing the contaminant, the openings 116 communicating with the interior 62 may be subjected to a negative pressure. For example, an active suction system (e.g., a pump) or a drain 118 may draw the purge gas from the housing 62. As also illustrated, one or more traps 114 (e.g., scoops, walls, barriers, passageways, screens, etc.) may be disposed across the collection areas 110a-c within the interior 62 to capture the contaminants swept away by the purge gas into the area 110c.

[0037] As in Fig. 3, the head 50 can generally be used and manipulated in an "upright" position, meaning that the source of the laser beam LB at the inlet 61a is vertically aligned somewhere above the workpiece beyond the outlet 61b. The laser beam LB is therefore directed downward in the vertical direction (along the Z-axis). Although this may not always be the case, this upright orientation is preferred for the head 50, as gravity can naturally help prevent splashes, debris, and the like from the laser process from affecting the head 50, contaminating the optics 55, etc.

[0038] For this reason, the nozzles 106a-d are preferably arranged toward the "top" or "upper" end of the housing 60 so that they inject the gas vertically downward over the optical components 70, 74, 80 into the collection areas 110a-c, which are arranged toward the "bottom" or "lower" end of the housing 60. This allows gravity to assist the purging process to remove contaminants from the optical components 70, 74, 80. In one implementation, the reflectors 70, 74 and associated mechanics are integral parts of the input / output modules (63a and 63c; Fig. 2) and the module (63b; Fig. 2), which includes the lens element 80 and the lens actuator system (84, 86), can be rotated about the optical axis A to adapt its orientation to other head orientations.

[0039] As previously mentioned, the lens element 80 is movable within the interior 62. Preferably, a mechanical structure or support 84 and an actuator or drive 86 are provided for moving the lens element 80 toward the "lowermost" or "bottom" end of the lens element 80 and the collection area 110c. This mechanical structure 84 may include bearings, joints, and the like connected to the drive 86, which may include an electric motor, an electromagnet, or other suitable device. Any debris generated by the mechanical structure 84, such as burrs, chips, particles, etc., would tend to fall due to gravity and be swept by the purge gas directly into the collection area 110c without passing over the lens 82.

[0040] According to one embodiment, the first reflector 70 may be a reflector cooled by a cooling assembly 72, which is only schematically illustrated in the extension 52. Apart from the cover slides (64, 66), which are less expensive consumables, this first reflector 70 is the only internal component of the housing 60 onto which contaminants can fall due to gravity. Accordingly, manufacturing this reflector 70 from a material with high thermal conductivity, e.g., copper, has advantages in terms of contamination resistance.

[0041] The second reflector 74 points vertically downward in the Z-direction and would not tend to attract contaminants. Therefore, the second reflector 74 may be a semi-transparent reflector, allowing laser and / or process light to pass through the second reflector 74 to a monitoring assembly 76, which is only schematically shown in the extension 54. It should be understood that the monitoring assembly 76 may utilize conventional sensors and optics for laser and / or process observations. Additionally or alternatively, this second reflector 74 may be movable to change the lateral placement of the focal spot FP on the workpiece WP, so the extension 54 may include a mechanism 78 for tilting and aligning the second reflector 74.

[0042] As in Fig. 3 and as previously mentioned, a control unit 30 may be used to control the operation of components of the system. For example, the control unit 30 may actuate valves, pumps 102, and the like to control the supply of purge gas in the cross-jet assembly 100 to the nozzles 106a-d. The control unit 30 may actuate valves, pumps, and the like to control the evacuation of purge gas from the interior of the housing 62 using the active suction system or vent 118. To monitor operation, the control unit 30 may include sensors (not shown) to measure the flow rate, pressure, temperature, etc. of the purge gas. When the control unit 30 is integrated with other functionalities for the laser processing head 50, the control unit 30 may move the lens element 80 and / or the reflectors 70, 74 in a cleaning cycle.

[0043] Another configuration of a laser processing head 50 of the present disclosure is shown in Fig. 4. Here, the head 50 includes similar components as those described above, so similar reference numerals are used. In contrast to the previous configuration, the inlet 61a of this head 20, at which the laser inlet (cable receptacle and feed fiber) is oriented horizontally. Accordingly, the laser radiation passes through the lens element 80 horizontally and is rotated vertically by a reflector 74. This configuration eliminates the need for the additional reflector (70; Fig. 3) is unnecessary, as it could be prone to fouling. This configuration also allows for the addition of purge gas elements to the cover slide (64, 66; Fig. 2). These added purge gas elements (not shown) may be constructed similarly to the components used for lens element 80.

[0044] In summary, internal contamination may not always be avoidable. The disclosed laser processing head 50 in Fig. 1 to 4 attempts to reduce the possible influence / interaction of internal contamination with laser radiation. The arrangement of the cross-jet nozzles 106a-d in the head 50 actively flushes or floods the surfaces of the optical components 70, 74, 80 in the internal optics 55. The internal cross-jet nozzles 106a-d are preferably directed at all optical surfaces impinged by the laser beam LB. In fact, the cover slides (64, 66; Fig. 2) Purge gas is used to remove contaminants.

[0045] The nozzles 106a-d are fed through the purge gas channel 104, and the emitted stream is delivered into the interior 62 of the head housing 60. Preferably, one or more collection areas 110a-c, metal wire mesh filters 112a-c, traps 114, and / or orifices 116 are used with the purge gas through the purge system 100 so that potential contaminants are collected, captured, and / or removed from the interior 62. Instead of metal wire mesh filters, other types of filters or cleanroom-compatible adhesive tapes may be used. Because the processing head 50 has few optical surfaces and because they are arranged in a vertical orientation, the cross-jet nozzle 106a-d and the purge gas can be more effective.

[0046] During operation of the laser processing head 50, purging with the purge gas, such as clean nitrogen gas, can be performed continuously or intermittently. At the same time, negative pressure can be applied in the collection areas 110a-c of the housing 60 using the active suction system or the drain 118. Incoming purge gas from the inlet nozzles 106a-d is directed from above onto the optical elements 70, 74, 80. Due to the orientation of the lens element 80, contaminants are not expected to become trapped on the lens 82 and its mount 84 while the contaminants are being purged. The negative pressure applied beneath the lens element 80 creates a well-defined particle sink in the collection areas 110a-c.

[0047] In addition to removing contaminants such as particles, dust, dirt, etc., the cross-jet assembly 100 can also help remove vapors and evaporating substances from the interior of the housing 62. Combustion can generate vapors that can cool relatively quickly. The cross-jet assembly 100, which includes the active extraction system's vent 118, can remove the vapors directly, preventing the vapor from settling on the lens element 80 or other surfaces. In addition to vapors, evaporating substances (e.g., coolant residue, oils, and greases) can also be removed from the interior 62 using the active extraction system or vent 118.

[0048] When used during operation of the laser beam LB, the purge gas is preferably an inert gas, such as nitrogen, to limit any oxidation reaction between particle(s) and the laser beam LB, thus preventing burns to the lens 82 and reflectors 70, 74. The purge gas can be used when the laser is off. In this case, the use of an inert gas is not necessary, as any other gas could be used.

[0049] To enhance the effects, the head 50 can be aligned or operated in an intensive cleaning position and / or a movement pattern can be performed for the lens element 80, the reflector 74, etc. For example, it is possible to vibrate the optical component 70, 74, 80 to shake off contaminants on the surfaces. This shaking can be combined with a targeted movement of the optical element 70, 74, 80 in front of the cross-jet nozzle 106a-d. For example, the drive 86 can move the lens 82 relative to the nozzles 106c-d so that the purge gas can better wipe the surfaces of the lens 82. In such a configuration, the nozzles 106c-d for the lens element 80 can be stationary in the housing 60. This can be practical given the small movement expected for the lens element 80.Alternatively, the nozzles 106c-d may be movable together with the lens element 80 using suitable mounts, conduits, flexible joints, etc. In either case, a wiping action of the purge gas on the optical element 70, 74, 80 can be achieved. The reflector 74, if movable, can also be manipulated relative to the nozzle 106b. The control unit 30 can control the components for these cleaning operations.

[0050] Typically, the processing head 50 may include capacitive height sensing components at its outlet 61b, allowing the distance of the head's laser nozzle from a workpiece to be determined. In such situations, purge gas is used to prevent contamination of the height sensor. Accordingly, the purge gas used by the cross-jet assembly 100 may be further routed to the capacitive height sensing components of the laser processing head 50, allowing the gas to still serve as a purge gas during the laser process.

[0051] The foregoing description of preferred and alternative embodiments is not intended to limit or restrict the scope or applicability of the inventive concepts conceived by the applicants. Having the benefit of the present disclosure, it will be understood that the above-described features may be utilized in accordance with any embodiment or aspect of the disclosed subject matter, either alone or in combination with any other described feature in any other embodiment or aspect of the disclosed subject matter.

Claims

[1] A laser processing head (20) for directing a laser beam (LB), the laser processing head (20) comprising: - a housing (60) having an interior for the passage of a laser beam (LB) along an optical axis (A) from an inlet (61a) to an outlet (61b); - at least one reflector (70 or 74) arranged inside the housing (60) and reflecting the laser beam (20) along the optical axis (A) between the inlet (61a) and the outlet (61b); - a lens element (80) arranged inside the housing (60), the lens element (80) being movable along the optical axis (A) and being configured to adjust a focal length of the laser beam (LB); - one or more collection areas (110a-c) arranged inside and configured to collect contamination directed by a purge gas; - one or more nozzles (106a-d) configured to direct the purge gas over one or more of the at least one reflector (70 or 74) and the lens element (80), wherein the one or more nozzles (106a-d) comprise a first of the one or more nozzles (106a-d) disposed adjacent to an end of the lens element (80) and configured to direct the purge gas over a first side of the lens element (80); and wherein the one or more collection regions (110a-c) comprise a first of the one or more collection regions (110a-c) disposed internally adjacent the lens element (80) and downstream of the first nozzle. [2] The laser processing head (20) of claim 1, wherein the at least one reflector comprises a first reflector (70); wherein the one or more nozzles (106a-d) comprise a first of the one or more nozzles (106a-d) disposed adjacent to the at least one reflector (70) and configured to direct the purge gas over the at least one reflector (70); and wherein the one or more collection regions (110a-c) comprise a first of the one or more collection regions (110a-c) disposed internally adjacent the at least one reflector (70) and downstream of the first nozzle. [3] The laser processing head (20) of claim 2, wherein the at least one reflector comprises a second reflector (74); wherein the one or more nozzles (106a-d) comprise a second of the one or more nozzles disposed adjacent to the second reflector (74) and configured to direct the purge gas over the second reflector (74); and wherein the one or more collection regions (110a-c) comprise a second of the one or more collection regions (110a-c) disposed internally adjacent to the second reflector (74) and downstream of the second nozzle. [4] The laser processing head (20) according to claim 3, wherein the first reflector (70) comprises a reflector having a high thermal conductivity and being cooled; and / or wherein the second reflector (74) comprises a semi-transparent reflector; and / or wherein at least one of the first and second reflectors (70, 74) is movable to deflect the focal point of the laser beam (LB). [5] The laser processing head (20) according to claim 1, wherein: - the one or more nozzles (106a-d) comprise a second of the one or more nozzles disposed adjacent to the one end of the lens element (80) and configured to direct the purge gas over a second side of the lens element (80); and / or - the lens element (80) is movable internally on a mechanical structure arranged towards the second end of the lens element (80). [6] The laser processing head (20) of claim 1, comprising a source (102) disposed in communication with the one or more nozzles (106a-d) and configured to direct the purge gas to the one or more nozzles (106a-d). [7] The laser processing head (20) of claim 1, wherein each of the one or more collection areas (110a-c) comprises: - a filter (112a-c) configured to allow the purge gas to pass through and configured to capture the contaminant; and / or - an adhesive surface configured to capture the contaminant. [8] The laser processing head (20) of claim 1, wherein the housing (60) includes at least one port (116) arranged in communication with the interior, the at least one port (116) being configured to allow the purge gas to pass out of the interior. [9] The laser processing head (20) of claim 8, wherein the at least one port (116) comprises a membrane configured to allow the purge gas to pass from the interior and prevent backflow into the interior. [10] The laser processing head (20) of claim 8, further comprising a pump arranged in communication with the at least one port (116) and configured to draw the purge gas from the housing (60). [11] The laser processing head (20) of claim 1, wherein each of the one or more collection areas (110a-c) comprises a filter (112a-c) configured to allow the purge gas to pass therethrough and configured to capture the contaminant; and wherein the housing (60) comprises at least one opening arranged in communication with the purge gas from the filter (112a-c) and to which a negative pressure is applied. [12] The laser processing head (20) of claim 1, wherein the one or more collection regions (110a-c) comprise one or more traps disposed over the interior and configured to capture the contaminant. [13] The laser processing head (20) of claim 1, wherein the inlet (61a) comprises a cover slider (64); and / or wherein the outlet (61b) comprises a cover slider (66); and / or wherein the lens element (80) comprises a single lens (82) or a single group of lenses. [14] A laser processing head (20) for directing a laser beam (LB), the laser processing head (20) comprising: - a housing (60) having an interior for the passage of a laser beam (LB) along an optical axis (A) from an inlet (61a) to an outlet (61b); - a first reflector (70) arranged inside the housing (60) and reflecting the laser beam (LB) along the optical axis (A) from the inlet (61a); a second reflector (74) arranged in the housing (60) and reflecting the laser beam (LB) from the first reflector (70) along the optical axis (A) towards the outlet (61b); - a lens element (80) arranged inside the housing (60) between the first and second reflectors (70, 74), the lens element (80) being movable along the optical axis and being configured to adjust a focal length of the laser beam (LB); - one or more nozzles (106a-d) configured to direct purge gas over one or more of the first reflector (70), the second reflector (74) and the lens element (80); and - one or more collection areas (110a-c) arranged inside and configured to collect contamination directed by the purge gas; - at least one of: (i) a source (102) arranged in communication with the one or more nozzles (106a-d) and configured to direct the purge gas to the one or more nozzles (106a-d), and (ii) a drain (118) arranged in communication with the housing (60) and configured to draw the purge gas from the housing (60); and - a control unit configured to operate at least one of the source (102) and the drain (118), wherein at least one of the first and second reflectors (70 or 74) is movable within the housing (60); and wherein the control unit is configured to move at least one of: (a) the lens element (80) and (b) the at least one of the first and second reflectors (70, 74) with respect to the operation of the at least one of the source (102) and the drain (118). [15] A laser cutting machine used with a laser source to cut a workpiece, the machine comprising: - a laser processing head (20) receiving laser radiation (LB) from the laser source, the laser processing head (20) comprising at least: - a housing (60) having an interior for the passage of the laser radiation (LB) along an optical axis (A) from an inlet (61a) to an outlet (61b); - at least one reflector (70 or 74) arranged inside the housing (60) and reflecting the laser radiation (LB) along the optical axis (A) between the inlet and the outlet; - a lens element (80) arranged inside the housing (60), the lens element (80) being movable along the optical axis (A) and being configured to adjust a focal length of the laser radiation (LB) beyond the outlet (61b); - one or more nozzles (106a-d) configured to direct purge gas over one or more of the at least one reflector (70, 74) and the lens element (80); and - one or more collection areas (110a-c) arranged inside and configured to collect contamination directed by the purge gas; and - an actuator supporting the laser processing head (20) and configured to manipulate the laser processing head (20) with respect to the workpiece - at least one of: (i) a source (102) arranged in communication with the one or more nozzles (106a-d) and configured to direct the purge gas to the one or more nozzles (106a-d), and (ii) a drain (118) arranged in communication with the housing (60) and configured to draw the purge gas from the housing (60); and - a control unit configured to operate at least one of the source (102) and the drain (118), wherein the at least one reflector (70 or 74) is movable within the housing (60); and wherein the control unit is configured to move at least one of: (a) the lens element (80) and (b) the at least one reflector (70 or 74) related to the operation of at least one of the source (102) and the drain (118).

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