Patent Publication Number: US-2022234138-A1

Title: Nozzle adapter for laser cutting head

Description:
BACKGROUND OF THE DISCLOSURE 
     Laser cutting heads use a laser beam to perform cutting operations on sheets of different materials (typically, different types of metals and metallic compounds). The laser cutting process requires precise control of the cutting head and requires particular control of the gap between the tip of the cutting head&#39;s nozzle (where the laser beam exits) and the surface of the material being cut (referred to at times as the “workpiece”). For this purpose, the laser cutting head uses optics and sensors for controlling the cutting process. 
     In general terms, the laser cutting head converts the energy of a high-power laser source (typically a CO 2  or YAG laser) into a laser beam able to cut through (sever) a metal sheet in a precise, controlled manner. The cutting head may pass the beam through a series of lenses and may use optical fibers as the guiding path for the beam. The cutting head focuses the beam to a spot size desired for the cutting process, and the focused beam is directed through a nozzle of the cutting head and toward the sheet of material to be cut. 
     A companion gas (typically nitrogen or oxygen and referred to at times as a cutting or process gas) can also be delivered to the surface of the sheet along with the laser beam. The gas functions either to assist in the melting process (e.g., “oxy-fuel burning process”) or to help blow molten material away from the workpiece. Although the cutting gas used during lasing process can blow material outward concentrically away from the nozzle, the nozzle needs to be positioned at a particular standoff from the workpiece to achieve proper cutting and to avoid molten material contaminating the nozzle and the cutting head. 
     A wide variety of laser cutting heads are manufactured for different purposes. Each type of cutting head requires the ability to adjust, control, and monitor the gap between the tip of the nozzle and the workpiece&#39;s surface. One typical system for monitoring (and controlling) this gap is based upon a measured capacitance between the nozzle tip and the workpiece (with the air gap between the two serving as the dielectric for the capacitor). To function properly, both the nozzle tip and the workpiece need to be conductive and connected to a voltage source of a measurement system. 
     Numerous types of nozzles are used on the laser cutting heads. These nozzles are typically composed of metal, such as copper, and have a passage therethrough for delivery of the focused laser beam and the cutting gas. Nozzles can include one or more component layers. The outward shape of the nozzle as well as any internal profiles of the through-passage can vary from nozzle to nozzle depending on the implementation and their use. 
     During customary use, the nozzle can become worn and contaminated, requiring replacement. During bevel cutting at acute angles, features associated with the nozzle may interfere with sensor measurements to control the standoff or gap of the nozzle from the workpiece. At very acute angles, existing arrangements of nozzles and adapters may not prevent contamination from interfering with the optics and sensing of the laser cutting head. 
     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. 
     SUMMARY OF THE DISCLOSURE 
     An apparatus disclosed herein is used to connect a nozzle to a laser cutting head. The head has a sensor assembly for capacitive sensing, an opening for communicating a laser process, and an orifice for communicating a purge gas. The apparatus comprises a conductive adapter and a cover. The conductive adapter has first and second ends and has a first passage for communicating with the laser process from the opening. The first end is affixable to the sensor assembly, and the second end is affixable to the nozzle. The conductive adapter has a collar disposed thereabout, and the collar defines one or more second passages therethrough. The cover is configured to position between the head and the collar and is configured to enclose a space communicating the purge gas from the orifice to the one or more second passages of the collar. 
     A laser cutting head disclosed herein uses a nozzle to deliver a laser process. The head comprises a housing, a conductive adapter, and a cover. The housing has a sensor assembly for capacitive sensing, an opening for communicating the laser process, and an orifice for communicating a purge gas. The conductive adapter has first and second ends and has a first passage for communicating with the laser beam of the opening. The first end is affixed to the sensor assembly, and the second end is affixed to the nozzle. The conductive adapter has a collar disposed thereabout, and the collar defines one or more second passages therethrough. The cover is disposed between the end of the housing and the collar and encloses a space communicating the purge gas from the orifice to the one or more flow passages of the collar. 
     The foregoing summary is not intended to summarize each potential embodiment or every aspect of the present disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  illustrates a perspective view of a laser cutting head according to the present disclosure. 
         FIG. 1B  illustrates a laser cutting system having a robotic arm and a laser cutting head according to the present disclosure. 
         FIG. 2A  illustrates a perspective view of a nozzle attachment of the present disclosure. 
         FIG. 2B  illustrates an elevational view of the nozzle attachment of the present disclosure during acute angle cutting with a laser cutting head. 
         FIG. 2C  illustrates a perspective view of the nozzle attachment having an alternative nozzle. 
         FIG. 2D  illustrates a portion without nozzle and adapter in an exposed view on a laser cutting head. 
         FIG. 3A  illustrates a cross-sectional view of a nozzle attachment of the present disclosure on a laser cutting head. 
         FIG. 3B  illustrates a schematic view showing the laser beam, process gas, and purge gas relative to components of the nozzle attachment of  FIG. 3A . 
         FIG. 4A  illustrates a cross-sectional view of the nozzle attachment of the present disclosure having a different nozzle. 
         FIG. 4B  illustrates a schematic view showing the laser beam, process gas, and purge gas relative to components of the nozzle attachment of  FIG. 4A . 
         FIG. 5  illustrates a cross-sectional view of another nozzle attachment of the present disclosure on a laser cutting head. 
     
    
    
     DETAILED DESCRIPTION OF THE DISCLOSURE 
       FIG. 1A  illustrates a perspective view of a laser cutting head  30  according to the present disclosure. The laser cutting head  30  includes a housing  32  that holds various internal optics. A connection at one end of the housing  32  can couple to a laser cable  40 , which conducts laser energy into the head  30 . An output assembly or nozzle attachment  50  on the other end of the housing  30  has a nozzle  120  from which a laser beam is directed for cutting operations. The nozzle attachment  50  allows the focused laser beam to be emitted from the housing  32  for achieving the purposes of the lasing operation, such as welding, additive manufacture, cutting, etc. The nozzle attachment  50  also includes sensing components (not shown) for monitoring a standoff or gap of the nozzle  120  from a workpiece, as disclosed in more detail below. 
     To protect the internal optics inside the housing  32 , the head  30  may include a cover slide cartridge  34  that holds a replaceable cover slide. This cover slide acts as a transparent window between the interior of the housing  32  (having the internal optics) and the external environment (exposed to the lasing process). Removal and replacement of the cartridge  34  can be made through an access door in the side of the head  30 . The nozzle attachment  50  also protects the laser cutting head  30  in ways disclosed below. 
     In general, the laser cutting head  30  can be used with a gantry assembly, a robotic arm, or other apparatus so the head  30  can be moved relative to a workpiece. For example,  FIG. 1B  illustrates a laser cutting system  10  having the laser cutting head  30  connected to a robotic arm  20 , which is operable to manipulate the head  30  relative to a workpiece WP subject to the laser processing of the present disclosure. Cabling  22  communicates control, sensing, and power to the laser cutting head  30 . The cabling  22  also communicates a flow of any gases used in the lasing cutting process as described herein. The laser cable  40  delivers the lasing power to the head  30 , which directs the laser beam from the nozzle attachment  50  on the end of the head  30 . 
     In general, the laser cutting system  10  includes a control system  12  that controls operation of the various components, namely the robotic arm  20 , cutting head  30 , etc. The system  10  likewise includes a measurement system  14 , which in the present example is used with the control system  12  to measure the standoff or gap of the cutting nozzle  120  from the workpiece WP to facilitate the cutting operation. 
     Depending on the shape of the workpiece WP and the cuts to be made, the head  30  can be manipulated by the robotic arm  20  at various angles and orientations relative to the workpiece WP. During the lasing process, components of the nozzle attachment  50  can sense the distance of the nozzle  120  from the workpiece WP. This is achieved using capacitance between the nozzle  120  and the workpiece WP, with the air gap between them providing the dielectric. This sensed capacitance allows the positioning of the head  30  to be controlled relative to the workpiece WP to achieve the desired lasing. 
     As expected, heat from the lasing process damages the nozzle  120  during use. Additionally, the lasing process can produce debris, cast off, splatter, blow back, etc. that can damage the nozzle  120  and can diminish the capacitive sensing of the head  30 . Features of the nozzle attachment  50  of the present disclosure can help mitigate the damage to the nozzle  120  and can protect the capacitive sensing. 
       FIG. 2A  illustrates a perspective view of the nozzle attachment  50  of the present disclosure. The nozzle attachment  50  includes a cap  52  attached to the head  30 . An adapter  110  is connected to internal components, and the nozzle  120  is attached to the adapter  110 . A cover  130  is positioned between the adapter  110  and the cap  52 . To cool the nozzle  120  and to create additional shielding from debris, the adapter  110  conducts a purge gas through orifices  118  directly adjacent the nozzle  120 . 
     At very acute angles of the head  30 , such as shown in  FIG. 2B , components of the nozzle attachment  50  can be positioned close to the workpiece WP and can be subject to more debris and interference. To protect the components while allowing the head  30  to be used in the acute angle of operation, the nozzle attachment  50  includes the cover or girdle  130  that encloses portion of the adapter  110  for the nozzle  120 . As described in more detail below, the cover  130  also encloses portions of the head&#39;s housing, which has sensing components and an orifice for the purge gas flow. The cover  130  can have a metal body with an electrical isolating shielding, such as a ceramic coating. In other configurations, the cover  130  can be made from plastic or ceramic. 
     Depending on the laser process, different nozzles may be used on the nozzle attachment  50 . For example,  FIG. 2C  shows the nozzle attachment  50  having a different, larger nozzle  120 ′ attached to the adapter  110  than show previously. The benefit of the nozzle attachment  50  in cooling the larger nozzle  120 ′ and creating additional shielding with purge gas can still be achieved with such a larger nozzle  120 ′ in addition to the protection of sensing elements provided by the cover  130 , adapter  110 , and the like. Further details will be described much later. 
     Briefly,  FIG. 2D  shows the nozzle attachment  50  having the nozzle ( 120 ), adapter ( 110 ), and cover ( 130 ) removed to reveal internal components. Elements of the sensing assembly  60  are shown and include a ceramic body  62  having a conductive holder  66  therein. The adapter ( 110 ) threads into this conductive holder  66 . The ceramic body  62  is surrounded by a shielding  72 , which defines an annular gap  54  with the lip of the attachment&#39;s cap  52 . This annular gap  54  acts as an orifice for purge gas as described below. As will be appreciated, the features of the nozzle attachment  50  disclosed herein can protect these internal elements of the sensing assembly  60  from debris and the like during the lasing process. 
     Turning now to more details,  FIG. 3A  illustrates a cross-sectional view of a nozzle attachment  50  of the present disclosure on a laser cutting head  30 . As noted, the head  30  is useable for laser processing with a nozzle  120 . During the laser processing, a laser beam (B) and a process gas (G) is emitted from the head  30  and out the nozzle  120  on the nozzle attachment  50 . Additionally, a purge gas (P) is also conducted from the head  30  and out of the nozzle attachment  50  adjacent the nozzle  120 . This purge gas (P) achieves the purposes disclosed herein of (i) helping to cool the nozzle  120  and (ii) creating additional shielding about the active processing area beyond the nozzle  120 . 
     The head  30  includes a housing  32  having an end, which can include an end plate  38  from which the laser beam (B), the process or cutting gas (G), and the purge gas (P) can pass. The laser beam (B) and the process gas (G) pass from the interior of the housing  32  through an opening  36  and then through the sensor assembly  60 , while the purge gas (P) can pass from elsewhere in the housing  32  through a pathway or other opening  35 , which is only schematically shown. Components of the sensor assembly  60  are affixed to the end of the housing  30 , and the cap or fixture  52  covers the assembly  60  on the end of the housing  30 . The conductive adapter  110  is attached to the sensor assembly  60 , and the cover or girdle  130  is disposed between the sensor assembly  60  and the conductive adapter  110 . Finally, the nozzle  120  is attached to the conductive adapter  110 . 
     The cap  52  functions as an outer protective element for the sensor assembly  60 , protecting the assembly  60  from exposure to other manufacturing/fabrication elements that may damage the assembly  60  or otherwise disrupt its operation. As shown in detail, the cap  52 , which can be conical, has a large circumferential end that can thread to the end plate  38  fit against a retaining ring  70  used between the sensor assembly  60  and the base plate  38 . A plurality of gaskets can be used to seal the arrangement against external influences, as well as to prevent intrusion of the purge gas (P). 
     The nozzle attachment  50  has an orifice  54  from which some of the purge gas (P) passes. For example, an annular space  54  is provided between a lip of the cap  52  and the outer edge of the sensing assembly  60 . Purge gas (P) can pass out of this annular space  54  toward the end of the adapter  110  and nozzle  120  for the purposes disclosed herein. 
     For its part, the sensor assembly  60  has a ceramic body  62  and a conductive holder  66 . The ceramic body  62  has a first passage  64  through which the laser beam (B) and any process gas (G) can pass. The conductive holder  66  is disposed in the first passage  64 . The sensor assembly  60  can further include a conductive grounding shield  72  disposed about the ceramic body  62 . As discussed in more detail below, the conductive holder  66  and the conductive grounded shield  72  are connected in electrical communication with a voltage and a ground respectively. 
     The conductive adapter  110  has first and second ends  114 ,  116  with a second passage  112  through which the laser beam (B) and any process gas (G) can pass. The first end  114  is configured to affix to the conductive holder  66 , while the second end  116  defines a receptacle into which the nozzle  120  is affixable. For example, the first end  114  can include external threading that threads into the conductive holder  66 . The receptacle  116  can define internal threading to which the nozzle  120  threads. For its part, the nozzle  120  defines a passage  122  that extends therethrough from end  126  to end  124  for passage of the laser beam (B) and process gas (P). 
     The conductive adapter  110  has a collar  115  disposed thereabout, and the cover  130  is disposed between the sensor assembly  60  and the collar  115 . As shown, the cover  130  can have a conical shape having a large circumferential edge configured to engage the cap  52  and having a small circumferential edge configured to engage the collar  115  of the conductive adapter  110 . The conductive adapter  110  can include a gasket seal  117  disposed about the collar  115  to sealably engage the cover  130 . 
     The collar  115  defines one or more gas flow passages  118  therethrough from one side to the other for passage of some of the purge gas (P) as noted herein. In this way, the cover  130  encloses an internal space  55  communicating the purge gas (P) from the orifice  54  to the one or more flow passages  118  of the collar  115 . One or more exits of the one or more flow passages  118  in the collar  115  are thereby preferably disposed directly adjacent the nozzle  120 , which can increase the cooling of the nozzle  120  and prolong its operational life. 
     As will be appreciated, the adapter  110  with its flow passages  118  can assist in the ejection of the purge gas (F), which can effectively prevent debris from reaching components of the head  30  and the nozzle attachment  50 . The adapter  110  with its flow passages  118  also controls the diffusion area and size of the purge gas&#39; stream, which can be tailored to the cutting operation to be performed. 
     As will be appreciated, the cutting nozzle  120  can assist in the ejection of the cutting or process gas (G) used in the cutting operation. The size of the nozzle&#39;s aperture  124  may be selected based on the thickness of the material to be cut. The nozzle  120  helps prevent the molten material from the workpiece reaching back into the laser head  30  so that internal components of the laser head  30  can be protected. The nozzle  120  also provide a capacitance signal for use in adjusting the standoff of the lasing head  30  by its adjustment system to maintain a stable lasing operation. 
     In some arrangements, the internal shape of the laser head nozzle  120  can direct the flow and pressure of the process gas (G). A single layer nozzle  120  can be used in melting cutting where nitrogen may be used as an auxiliary gas to cut stainless steel and aluminum plate. A double-layer nozzle  120  can be used with oxygen as an auxiliary gas for cutting carbon steel. Typically, the nozzle  120  is conical in shape and can have a single layer or multiple layers. For example, a double-layer nozzle can have an inner core to increase the velocity of the process gas (G), which has a number of advantages. The nozzle aperture  124  and the nozzle&#39;s thickness is configured for the implementation at hand. 
     Turning now to details of the sensor assembly  60  used for sensing the stand-off of the nozzle  120  from a workpiece, the cylindrical ceramic body  62  is used as a base element of the sensor assembly  60 . The ceramic material of the body  62  is insulative. Electrical connections between the laser cutting head nozzle  120  and an external measurement system ( 14 ) can be sintered to the outside of (or embedded within) cylindrical ceramic body  62 . In this manner, the electrical connections are permanently fixed in place and prevented from moving (even in the presence of “high g” conditions) and are able to function properly in the presence of high temperatures. 
     These electrical connections can include: a pair of electrical conductors (wires)  82 ,  86 , the conductive holder  66 , the outer cylindrical shield  72  (also conductive), and a socket connector  65 . The conductive adapter  110  and the nozzle  120  engage with conductive holder  68 . Together, these direct the laser beam (B) and any process gas (G) out of the cutting head  30  toward the workpiece. 
     The socket connector  65  can be a coaxial cable connector, including a central conductor and an outer ground conductor (with insulating material disposed between them). One wire  86  is used to conduct an electrical signal (voltage) along the central conductor to the conductive holder  66 , which is itself formed of a conductive material (for example, stainless steel). In assembling the laser cutting head  30 , the adapter  110  is threaded into the conductive holder  66  (in particular, screwed in place by the mating threads), and the nozzle  120  is threaded into the adapter  110 . As a result, the nozzle  120  is electrified by virtue of the connections established through wire  86  and threaded holder  66 . 
     The other wire  82  is positioned within the ceramic body  62  to create the conduction path between for the outer ground or shield  72 . This outer shield  72  takes the form of a sleeve that is designed to slip over and contact the outer surface of cylindrical ceramic body  62 . The shield  72  is permanently fixed in place around ceramic body  62  and is preferably formed of stainless steel. 
     The combination of the conductive holder  66 , the ceramic body  62 , and the shield  72  provides the connection arrangement for energizing the attached nozzle  120 , minimizing problems with internal interference and parasitic induction that would otherwise affect the capacitive measurements performed by the associated measurement system  14 . In addition to the cap  52 , the cover  130  used in conjunction with the collar  115  and the seal  117  of the adapter  110  protects these components of the sensing assembly  60  during operations, while still allowing the head  30  to be used at small acute angles as noted herein. 
     As already noted, for example, the conical cap  52  having a large circumferential end attached to the end  38  of the housing  30  and having a small circumferential end defining the annular gap  54  about the ceramic body  62  for the passage of the purge gas (P). A circumference of the collar  115  of the conductive adapter  110  lies within a conical angle (A) extending from a tip of the nozzle  120  to the large circumferential end of the conical cap  52 . This configuration allows the head  30  to be positioned at small acute angles relative to a workpiece during lasing operations, as previously noted with respect to  FIG. 2B . 
     As can be seen, should any molten debris or the like be able to reach the annular gap  54 , the contamination can obstruct the flow of purge gas (P) from the head  30 . Moreover, any molten debris or the other contamination reaching the sensor assembly  60  may interrupt its sensing capabilities. To that end, the cover  130 , the collar  115  of the adapter  110 , the seal  117 , and the other features protect the gap  54  and the sensor assembly  60 . Moreover, the directed purge gas (P) can actively cool the nozzle  120 , which prevents overheating/wear. The purge gas (P) can also be used as a curtain (shielding) for the cutting gas (G) stream. 
     For instance,  FIG. 3B  illustrates a schematic view showing the laser beam (B), process gas (G), and purge gas (P) relative to components of the nozzle attachment  50  of  FIG. 3A . Both gas streams (P, G) are independently adjustable in terms of flow, pressure and type of gas. This gives operators the ability to create an inert gas curtain from the purge gas (P) around any oxygen-based or other process gas (G). Additionally, the angle of the purge gas (P) stream can be adjusted to the required needs of the cutting operation. For example, the purge gas (P) stream can be angled towards the work piece/material surface so that the purge gas (P) can act as a process jet, cooling down/deflecting process emissions away from the head  30  and the gantry  20 . The purge gas (P), as a separately supplied gas, aims at protecting the sensor measurement system against process-based contamination, such as spatter particles, fumes, and general dirt. Ultimately, the directed application of the purge gas (P) towards the process can be used as an active cooling media of the nozzle  120  and/or as an additionally process jet. 
     Turning to another configuration,  FIG. 4A  illustrates a cross-sectional view of the nozzle attachment  50  having a larger nozzle  120 ′, as mentioned previously. Similar components as in the other configurations have the same reference numerals and are not described again, but their details are incorporated herein. 
     As shown, the nozzle  120 ′ extends beyond the collar  115  of the adapter  110 . To allow the purge gas (P) to flow from the flow passages  118 , side chamfers  119  can be defined in the side of the collar  115 . The purge gas (P) from the flow passages  118  can escape outside the sides of the adapter  110  and can still achieve the purposes of cooling the nozzle  120 ′ and creating additional shielding. 
     For example,  FIG. 4B  illustrates a schematic view showing the laser beam (B), process gas (G), and purge gas (P) relative to components of the nozzle attachment  50  of  FIG. 3B . The nozzle adapter  110  cools down the nozzle  120 ′ by directing the purge gas (P) flow to the nozzle  120 ′. Additionally, the purge gas (P) can act like a jacket around the process gas (G), This function depends on the design of the nozzle  120 ′ and the nozzle adapter  110 . Here, the nozzle adapter  110  can produce a horizontal cross-jet of the purge gas (P) to prevent contamination. Yet, the purge gas (P) is still capable of cooling the nozzle  120 ). 
     An alternative configuration of the nozzle attachment  50  is shown in  FIG. 5 . Similar components as in the other configuration have the same reference numerals, but their details are incorporated herein. In this arrangement, the separate features of the conical cap and the cover from  FIGS. 3A &amp; 4A  are integrated together into a unitary cover  90 , which encloses a space  95  and defines the orifice  94  for the purge gas (P) to reach the ports  118  in the adaptor&#39;s collar  115 . 
     As disclosed herein, the nozzle attachment  50  can relieve problems during bevel cutting operations that may be encountered during operation. The nozzle attachment  50  can prevent contamination from getting inside the sensor assembly  60  and can produce the cooling effect with the purge gas (P) for cooling down the nozzle  120 . The adapter  110  and cover  130  are configured to not impact the capacitive sensor assembly  60  and system ( 14 ) of the cutting head  30 . Moreover, the attachment  50  has a modular design so the attachment  50  can be used with a number of different nozzle types. 
     The foregoing description of preferred and other embodiments is not intended to limit or restrict the scope or applicability of the inventive concepts conceived of by the Applicants. It will be appreciated with the benefit of the present disclosure that features described above in accordance with any embodiment or aspect of the disclosed subject matter can be utilized, either alone or in combination, with any other described feature, in any other embodiment or aspect of the disclosed subject matter. 
     In exchange for disclosing the inventive concepts contained herein, the Applicants desire all patent rights afforded by the appended claims. Therefore, it is intended that the appended claims include all modifications and alterations to the full extent that they come within the scope of the following claims or the equivalents thereof.