Abstract:
A system for identifying a laser machining nozzle on insertion of the laser machining nozzle into a laser machining head is provided. On its region insertable into the laser machining head, the laser machining nozzle has a shaping. Means for detecting or sensing the shaping are provided in the receiving region of the laser machining head provided for the laser machining nozzle.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims priority under 35 U.S.C. §119(a) to German Patent Application No. 10 2007 024 288.5, filed on May 23, 2007, the entire contents of which are hereby incorporated by reference. 
     TECHNICAL FIELD 
     The invention relates to an arrangement for identifying a laser machining nozzle on insertion of the laser machining nozzle into a laser machining head. 
     BACKGROUND 
     The replacement of laser machining nozzles on a laser machining head of a laser machine tool, for example, on a laser welding head or on a laser cutting head, is a repetitive process. 
     In the case of a 2D laser cutting system for sheet metals, particular importance is attached to the laser cutting head and hence also to the cutting nozzle. To obtain improved cutting results for different thicknesses of sheet, different nozzles are used. In existing laser cutting systems, sheets of different thickness can be loaded for processing onto the machine using automatic loading devices. A change of cutting nozzle is carried out with the aid of what is called a nozzle changer. The preliminary requirement for a fully-automated nozzle change is to identify the laser machining nozzle. 
     SUMMARY 
     The system described below provides a simple and reliable identification of a mounted laser machining nozzle for an automatable laser machining nozzle change. 
     In one general aspect, a system identifies a laser machining nozzle inserted into a laser machining head. The system includes a geometric feature on a region of the laser machining nozzle that is insertable into the laser machining head, and a detector system that is configured to sense the geometric feature. 
     Implementations can include one or more of the following features. For example, the detector system can include a sensor and a detector and circuitry. The sensor, the detector, and the circuitry can be remote from the laser machining head. The sensor can be within the laser machining head, and the detector and the circuitry can be remote from the laser machining head. The sensor can include contact elements. The sensor can be formed on a base body of the laser machining nozzle. The detector can be housed in a nozzle magazine that stores a plurality of laser machining nozzles for use in the laser machining head. The sensor can include contact elements that are formed by spring-supported contact pins. The geometric feature can be a shaping and the sensor can be configured to sense the shaping. 
     The geometric feature can be on a side that is remote from a laser machining process. The geometric feature can be formed by a sequence of ridges and grooves. The geometric feature can be formed by a coating. The coating can be an insulating layer or a coat of lacquer. 
     The geometric feature can be rotationally symmetric about a longitudinal axis of the laser machining nozzle. 
     In another general aspect, a laser machining nozzle inserted into a laser machining head is identified by inserting a region of a laser machining nozzle into a laser machining head to enable a sensor of a detector system to sense a geometric feature on the laser machining nozzle region. 
     Implementations can include one or more of the following features. For example, detector system can be enabled to sense the geometric feature by enabling contact between contact pins of a sensor of the detector and ridges of the geometric feature on a side of the laser machining nozzle that is remote from a laser machining process. The contact pins can move when contacting the ridges of the feature. 
     In another general aspect, a laser machining process includes inserting a laser machining nozzle into a laser machining head to enable processing a workpiece, and identifying the inserted laser machining nozzle by detecting using a detector system including a sensor that detects a geometric feature on a region of the laser machining nozzle. 
     In a further general aspect, a laser machining system includes a laser, a workpiece, and a laser machining head that directs the laser to the workpiece and receives a laser machining nozzle. The laser machining head includes a system for identifying the laser machining nozzle inserted into the laser machining head. The system includes a geometric feature on a region of the laser machining nozzle that is insertable into the laser machining head, and a detector system including a sensor that is configured to sense the geometric feature. 
     Implementations can include one or more of the following features. For example, the detector system can include a detector that receives a signal output from the sensor and produces a signal that is fed to a control system for identifying the inserted laser machining nozzle. The geometric feature can include a shaping formed on a body of the laser machining nozzle that is not facing the workpiece. 
     An advantage of the identification system and method described herein is that the coding in the case of the mechanical manufacture of the laser machining nozzle, such as the laser cutting nozzle, for example, can be incorporated into the laser cutting nozzle as a contour. The coding can work without electrical or electronic components in the laser cutting nozzle, which is typically made of an electrically conductive material and thus makes electronic coding challenging. The coding according is especially simple to manufacture and hence especially cost-effective. The identification unit can be housed either in the laser machining head or in a nozzle magazine. The invention operates with low susceptibility to failure without electronic circuits. Contact pins of the arrangement can be individually replaced. 
     The invention can be used when laser machining nozzles are exchanged with the aid of a nozzle changer and a nozzle magazine. Nozzle identification can alternatively, however, be useful without a nozzle changer. The invention therefore concerns nozzle identification in general. 
     Further advantages and characteristics of the present invention can be gathered from the following description given by way of example only with reference to the enclosed drawings. Features mentioned above as well as below can be used either individually or in conjunction. The following description is not to be regarded as an exhaustive enumeration but rather as examples with respect to a general concept underlying the present invention. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a laser cutting system; 
         FIG. 2  is a side view of a device for changing a laser cutting nozzle on a laser cutting head of the laser cutting system of  FIG. 1 ; 
         FIG. 3  is an exploded view of the device shown in  FIG. 2 ; 
         FIG. 4  is a longitudinal cross-sectional view of a laser cutting nozzle that can be used in the laser cutting system of  FIG. 1 ; 
         FIG. 5  is a perspective view of part of an arrangement for identifying the laser cutting nozzle used in the laser cutting system of  FIG. 1 ; 
         FIG. 6  shows a cross-sectional view of an enlarged scale of the arrangement of  FIG. 5 ; and 
         FIG. 7  is a plan view of the laser cutting nozzle of  FIG. 4 . 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows the basic construction of a laser machining system  1  for laser cutting or piercing, having a laser  2  such as a CO 2  laser, a control device  3 , a laser machining head  4 , and a workpiece support  5 . A generated laser beam  6  is guided with the aid of deflecting mirrors to the laser machining head  4  and, with the aid of mirrors in the laser machining head  4 , is directed onto a workpiece  8 , which can be a metal sheet. 
     Both piercing and laser cutting are assisted by adding a gas. Oxygen, nitrogen, compressed air, application-specific gases, or combinations of these gases can be used as cutting gases  9 . The gas ultimately used is dependent on which materials are being cut or pierced and which standards of quality are being demanded of the workpiece. 
     During cutting, operation is generally carried out with a gas pressure of up to 20 bar. Where the laser beam  6  strikes the metal sheet  8 , the material is fused, oxidized, or both. The resulting molten material is blown out together with the iron oxides. Particles and gases that are produced can be extracted from a suction chamber  11  with the aid of a suction mechanism  10 . 
     The laser machining head  4  includes a laser machining nozzle  12  (shown in  FIGS. 2 and 3 ) and the laser machining system  1  also includes a nozzle magazine  54  that houses a plurality of the laser machining nozzles  12  that can be used in the laser machining head  4 . The laser machining head  4  is moved to the nozzle magazine  54  to exchange the laser machining nozzle  12  within the head  4  with a new head from the magazine  54 . The exchange can occur after finishing a first laser processing task but before beginning a second laser processing task. 
     Referring also to  FIGS. 2 and 3 , the laser machining head  4  includes a device  13  that is used to replace the laser machining nozzle (for example, a laser cutting nozzle)  12  on the laser machining head  4 . The device  13  for changing the laser cutting nozzle  12  can be mounted with the aid of a connector device  14  on the laser cutting head  4 . A piece  15  of dielectric material is integrated in the device  13 . The device  13  includes a mechanism for changing the laser cutting nozzle  12  and the mechanism is covered by an external housing  16 . In addition, a first gas connection  17  and a second gas connection  18  for a pneumatic operation of the mechanism for changing the laser cutting nozzle  12  can be seen in  FIG. 2 . Operation of a locking and unlocking means of the laser cutting nozzle  12  is effected pneumatically using a process gas that is already available at the laser cutting head  4 . The process gas can be any gas used in laser processing including laser cutting or welding and it can include the cutting gases  9 , which are discussed above. The locking and unlocking means is described in patent application DE 102007024366, which is incorporated by reference herein in its entirety. The locking and unlocking means includes a part that can be pneumatically moved for locking or unlocking of the nozzle  12 . 
     The connector device  14  removably secures the device  13  to a laser machining head  4  and the dielectric piece  15  provides for distance control between the laser machining head  4  and the workpiece  8 . The device  13  also includes a ball cage  20  and a lifting cylinder  21  that enable replacement of the laser cutting nozzle  12 , and a plate  22  that is used to identify the laser cutting nozzle  12 , as described in detail below. 
     A detector system for identifying a specific laser machining nozzle  12  is described below in detail. The detector system includes a sensor at or near the laser machining nozzle  12  and a detector and associated circuitry that can be near to or remote from the laser machining nozzle  12 . The sensor can sense a coding on the laser cutting nozzle  12  and can be at least partly formed on the plate  22  of the device  13 . 
     In other implementations, the sensor can be formed remotely from the laser machining head  4 , for example, in the nozzle magazine  54  and can sense the identity of a new laser machining nozzle  12  inserted into the laser machining head  4 . Moreover, the sensor can be an optical sensor if housed in the nozzle magazine  54 . 
     Referring to  FIGS. 4 and 5 , the laser cutting nozzle  12  has a flat nozzle body  23  and a shank  24 . The coding on the laser cutting nozzle  12  can include geometric features such as ridges and grooves (in the example shown, three circumferential ridges  26 , which are separated from one another by grooves  27 ) that are arranged at a top side  25  of the nozzle body  23  remote from a workpiece or the process. 
     The nozzle body  23  can be made of an electrically conductive material and is formed by milling in a turning center. The grooves  27  and the ridges  26  therefore can be formed by milling or machining when forming the nozzle body  23 . The ridges  26  can be formed by application of a coating to the nozzle body. In other implementations, the ridges  26 , the grooves  27 , or both the ridges  26  and the grooves  27  can be formed by molding them into the nozzle body  23  during manufacture of the nozzle body  23 . 
     In other implementations, the ridges  26  can be formed as a coating that is sprayed or suitably formed on the nozzle body  23 . The ridges  26  formed as a coating can have the same shape as those shown in  FIG. 4 , for example. The coating can be an insulating layer or a coat of lacquer. 
     The dielectric piece  15  provides distance control by isolating the electrically conductive nozzle body  23  from the machining head  4 . The capacitance between the nozzle body  23  and the workpiece  8  to be machined is measured to determine the distance of the machining head  4  from the workpiece  8 . 
     The circumferential arrangement of the coding is advantageous from the point of view of manufacture. It is also sensible to mount the coding on the side remote from the laser machining process because in this case, the coding is not contaminated by the laser machining operation and can still be sensed even after several hours of operation. 
     The sensor on the plate  22  of the device  13  includes contact pins  28  arranged to face the coding of the laser cutting nozzle  12 . The contact pins  28  can be made of any suitable rigid material. 
     In  FIG. 5 , for the sake of clarity, the plate  22  and the top side  25  of the laser cutting nozzle  12  are illustrated with a substantial spacing. The contact pins  28  or any other type of sensor can be electrically connected with a detector through the contact plug  19 . As an alternative to the contact pins  28 , contact surfaces on the outside of the external housing  16  are possible. The detector produces an output signal that is sent to the control device  3  for identifying the nozzles  12 . The detector can be located at the laser machining head  4  or remote from the laser machining head  4 , for example, mounted at the workpiece support  5  or mounted at the control device  3 . In one implementation, the detector is mounted to the nozzle magazine  54  that is mounted at the workpiece support  5 . 
     In the operational state, the contact pins  28  contact the ridges  26 , to enable sensing of the ridges  26  and the grooves  27 . Such a sensing is shown by way of example in  FIG. 6  for a contact pin  28 . The contact pin  28  is spring-supported in a sleeve  29 . When the laser cutting nozzle  12  is inserted into the device  13 , the ridges  26  are pressed against the contact pins  28 . Such a contact and movement of the contact pins  28  triggers an electrical signal using any suitable actuation means (for example, the motion can close a switch that is coupled to an electrical current), which is transmitted to the detector through the contact plug  19  and then to the control device  3  (shown in  FIG. 1 ). 
     The number, geometric arrangement, or both of ridges  26  and grooves  27  produces a coding. Through the rotationally symmetrical construction of the coding, a defined installation position of the laser cutting nozzle  12  is not required. The total possible number of ridges  26  and grooves  27  that can be formed defines the number of coding options. The coding can be associated with a specific laser cutting nozzle  12 . The number of identifiable laser cutting nozzles  12  follows from that. For example, if four ridges  26  are formed, sixteen different coding options can be achieved. 
     Evaluation of a contact between the contact pin  28  and the ridges  26  is effected with the aid of the control device  3 . The signal can be checked for plausibility. 
     As can be seen from  FIG. 7 , a total of four contact pins  28  are arranged offset from one another along the radial direction and along the circumference, such that ridges  26  and grooves  27  arranged concentrically with respect to one another can be identified. 
     Other implementations are within the scope of the following claims.