Abstract:
A method and device for welding pin contacts and socket contacts to an optical waveguide, the welding device has a contact loading station, a contact transport carriage, a laser welding device, and an electrical control unit. The contact loading station has a socket contact transfer device and a pin contact transfer device. The contact transport carriage has a pin contact holder and a socket contact holder. The contact transport carriage is displaceable between the contact loading station and the laser welding station. The elecrical control unit controls the combination and number of socket-contacts and pin contacts transferred from the socket contact transfer device to the socket contact holder and from the pin contact transfer device to the pin contact holder without having to re-tool the welding device.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The invention relates to a method and device for welding socket contacts and/or pin contacts to optical waveguides. More specifically, the invention relates to a method and device for welding plastic contacts to plastic optical waveguides.  
         DESCRIPTION OF THE PRIOR ART  
         [0002]    It is known from DE 199 19 428 A1 to secure sleeve-like ferrules of plastic, into which a plastic optical waveguide has been introduced, to the optical waveguide by means of a laser welding process. The ferrules are also known as contacts and may take the form of a socket contact or a pin contact. Typically, one end of the optical waveguide is provided with the socket contact and another end of the optical waveguide is provided with the pin contact so that the two ends of the optical waveguide may be mated with each other.  
           [0003]    Assembly machines with welding devices already exist for manufacturing the optical waveguides wherein the socket contacts or the pin contacts may be welded to the optical waveguide ends. The socket contacts and the pin contacts are fed from a supply reel on a narrow piece of plastic material formed in one piece therewith to form a strip. As the contacts are unwound from the supply reel, the contacts are separated from the strip by a severing device and are positioned in a contact holder. An end of the optical waveguide is then introduced into the contact and the contact is welded to the associated end.  
           [0004]    The existing welding devices, which are generally of modular construction, are only capable of welding either the socket contacts or the pin contacts to the ends of the waveguides. To change from welding the socket contacts to welding the pin contacts or vice versa, a tool change or even a complete module change is required. Having to retool the welding device necessitates down time that negatively effects the output of the welding device. An example of such a welding device is manufactured by Tyco Electronics AMP GmbH, AMPerestrasse  12 - 14 ,  64625  Bensheim, Germany, under the name “MOST Laser Module.” 
           [0005]    It is therefore desirable to develop a welding device wherein socket contacts and/or pin contacts may be welded as desired to respective optical waveguide ends without having to re-tool the welding device and without effecting the output of the welding device.  
         SUMMARY OF THE INVENTION  
         [0006]    The invention relates to a welding device for welding pin contacts and socket contacts to an optical waveguide. The welding device has a contact loading station, a contact transport carriage, a laser welding device, and an electrical control unit. The contact loading station has a socket contact transfer device and a pin contact transfer device. The contact transport carriage has a pin contact holder and a socket contact holder. The contact transport carriage is displaceable between the contact loading station and the laser welding station. The elecrical control unit controls the combination and number of socket contacts and pin contacts transferred from the socket contact transfer device to the socket contact holder and from the pin contact transfer device to the pin contact holder without having to re-tool the welding device.  
           [0007]    The invention further relates to a method for welding pin contacts and socket contacts to an optical waveguide. The socket contacts and the pin contacts are transferred into respective socket contact holders and pin contact holders arranged on a contact transport carriage. The contact transport carriage is displaced to position the socket contacts and the pin contacts for receipt of the optical waveguide. The optical waveguide is welded to the socket contacts and the pin contacts at a laser welding station. The combination and number of the socket contacts and the pin contacts transferred to the socket contact holder and to the pin contact holder is controlled by an electrical control unit without having to re-tool the welding device. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]    [0008]FIG. 1 is a cross-sectional view along a longitudinal axis of a structural unit with an end of an optical waveguide provided with a pin contact;  
         [0009]    [0009]FIG. 2 is a perspective view of the structural unit of. FIG. 1;  
         [0010]    [0010]FIG. 3 is a radial cross-sectional view of the structural unit of FIG. 1;  
         [0011]    [0011]FIG. 4 is a plan view of the optical waveguide provided with two pin contacts;  
         [0012]    [0012]FIG. 5 is a plan view of the optical waveguide provided with a pin contact and a socket contact;  
         [0013]    [0013]FIG. 6 is a perspective view of a first embodiment of a welding device;  
         [0014]    [0014]FIG. 7 is a partial front view of the welding device of FIG. 6 in a first operating phase;  
         [0015]    [0015]FIG. 8 is a partial front view of the welding device of FIG. 6 in a second operating phase;  
         [0016]    [0016]FIG. 9 is a front view of a laser welding station of the welding device of FIG. 6;  
         [0017]    [0017]FIG. 10 is a partially schematic plan view of a second embodiment of the welding device; and  
         [0018]    [0018]FIG. 11 is a side view of the welding device of FIG. 10. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0019]    A structural unit  11  including an optical waveguide  13  and a pin contact  17  and/or socket contact  35  will first be described with reference to FIGS. 1 through 5. A first embodiment of a welding device  41  and a method thereof will then be described with reference to FIGS. 6 through 9. A second embodiment of the welding device  41  and a method thereof will thereafter be described with reference to FIGS. 10 and 11. It should be noted that the individual components and structural units of the embodiments shown in FIGS. 6 through 11 are known with regard to their construction and mode of operation, such that they will not be described in full herein. The components and structural units of known welding devices, such as the above-mentioned welding device “MOST Laser Module” made by Tyco Electronics AMP GmbH, will hereby be incorporated by reference.  
         [0020]    As shown in FIGS. 1 and 2, the structural unit  11  includes the optical waveguide  13  and the pin contact  17 . The optical waveguide  13  has an inner cladding  19  and an outer cladding  21 . The inner cladding  19  and the outer cladding  21  are removed from an end  15  of the optical waveguide  13 . The end  15  has an end face  25  set back  31  with respect to a contact end face  29  to protect the sensitive, optically important end face  25 . In practical embodiments, the optical waveguide  13  is set back  31  from 1/100 mm to 1/10 mm.  
         [0021]    The pin contact  17  is arranged on the end  15  of the optical waveguide  13 . The pin contact  17  consists of a plastic material that is more transparent than the material of the inner cladding  19 . The pin contact  17  has an internal diameter that substantially corresponds to an external diameter of the inner cladding  19 . The contact end face  29  is not positioned flush with the end  15  of the optical waveguide  13 . The pin contact  17  has a flange  23  with an end face that abuts an end of the outer cladding  21 . The flange  23  may also act as a stop for the socket contact  35  (not shown in FIGS. 1 and 2), when the pin contact  17  is mated with the socket contact.  
         [0022]    As shown in FIG. 3, the external circumference of the inner cladding  19  and the internal circumference of the pin contact  17  are welded together by laser welding at weld points  33 . In FIG. 3, the inner cladding  19  and the internal circumference of the pin contact  17  are welded together at three weld points  33 . Because the pin contact  17  consists of a plastic material that is more transparent than the material of the inner cladding  19 , the laser light can almost completely penetrate the pin contact  17  during irradiation and thereby produce welds in a radially outermost area of the inner cladding  19  of the optical waveguide  13 .  
         [0023]    [0023]FIG. 4 shows an example of the optical waveguide  13  with the pin contact  17  welded to each end thereof. FIG. 5 shows an example of the optical waveguide  13  with the pin contact  17  welded to one end and the socket contact  35  welded to another end thereof. Instances may also arise in which the optical waveguide  13  may have the socket contact  35  welded to each end thereof. The pin contacts  17  take a somewhat different form in FIGS. 4 and 5 than in FIGS. 1 and 2.  
         [0024]    The first embodiment of the welding device  41  will now be described in greater detail with reference to FIGS. 6 through 9. As shown in FIG. 6, the welding device  41  has an electrical control unit  75  and a base plate  43  provided with a centrally positioned laser welding station  57  attached to a setting panel  69  and a contact loading station  49 . The laser welding station  57  has a housing  59 . A wall  61  of the housing  59  has two optical waveguide feed funnels  63 . A cover  67  of the housing  59  is provided with a bracket  65 . The bracket  65  contains electrical data and control lines for connecting the setting panel  69  to the rest of the welding device  41 . The setting panel  69  includes a keypad  71  and a screen  73 .  
         [0025]    As shown in FIG. 9, the laser welding station includes a single displaceable laser  109 . It is also possible to provide two or more lasers instead of a single displaceable laser, in accordance with the module widths, which in the embodiment illustrated is 55 mm when two lasers are used or 27.5 mm when three lasers are used. The laser  109  produces a laser beam  111  and is arranged on a horizontally displaceable laser carriage  113 .  
         [0026]    The electrical control unit  75  is connected with the rest of the welding device  41  by an electrical cable  77  (only a cable end is shown in FIG. 6). The electrical control unit  75  has a programmable control device (not shown). The programmable control device (not shown) is preferably in the form of a microprocessor or a microcontroller wherein the selection of specific control programs and/or the setting of specific control parameters is possible by means of the setting panel  69 .  
         [0027]    Proximate the laser welding station  57  is the contact loading station  49 . The contact loading station  49  is arranged above the base plate  43  on a board  47  provided on a support  45  that extends from the base plate  43 . The board  47  has a stand  51 . An upper end of the stand  51  holds a socket contact supply reel  53  and a pin contact supply reel  55 . The socket contact supply reel  53  and the pin contact supply reel  55  may be located above the contact loading station  49 , as shown in FIG. 6, or beneath the contact loading station  49 , as shown in FIGS. 7 and 8.  
         [0028]    As best shown in FIGS. 7 and 8, the socket contact supply reel  53  and the pin contact supply reel  55  are wound with a strip  79  of either the pin contacts  17  or the socket contacts  35 . The strip  79  is formed by connecting neighbouring contacts  17 ,  35  by connecting webs  77 . Because the welding device  41  described herein is principally intended for welding plastic contacts to plastic optical waveguides, the pin contacts  17 , socket contacts  35 , and the connecting webs  77  preferably consist of the same plastic material and the connecting webs  77  and the contacts  17 ,  35  held therebetween are formed in one piece. The strip  79  is conveyed in a controlled manner via a conveying duct  81  to a strip feed roller for socket contact feed  83  or a strip feed roller for pin contact feed  85 . The respective strips  79  are deflected from an approximately vertical conveying direction to a substantially horizontal conveying direction during feeding.  
         [0029]    As shown in FIG. 7, a pin contact separating device  87  and a socket contact separating device  89  are located proximate the contact loading station  49 . Each separating device  87 ,  89  has a cutting punch  91 ,  93 , respectively, movable in a vertical direction. On both sides of each cutting punch  91 ,  93  is a connecting web holding-down device  95  and a counter-cutter  97 . The cutting punches  91 ,  93  and the counter-cutter  97  shear-off the connecting webs  77  located on each side of the contacts  17 ,  35 , when the cutting punch  91 ,  93  moves upward. An extraction duct  99  is arranged in the space formed between the two mutually facing connecting web holding-down devices  95  of the separating devices  87 ,  89 . The extraction duct  99  extracts the connecting webs  77  severed from the contact strips  79 .  
         [0030]    As shown in FIG. 7, a contact transport carriage  101  is arranged above the separating devices  87 ,  89 . The contact transport carriage  101  may be displaced in relation to the separating devices  87 ,  89  in a horizontal direction (with regard to FIG. 7). A number of contact holders  103 ,  105  are arranged on the contact transport carriage  101 . Four contact holders  103 ,  105  are arranged in the embodiment illustrated. Two of the contact holders are socket contact holders  103  and two of the contact holders are pin contact holders  105 . The socket contact holders  103  and the pin contact holders  105  are arranged alternately in the carriage displacement direction and at a predetermined distance from each other. Each of the contact holders  103 ,  105  has a clamping arm pair  107 . Each clamping arm pair  107  has two clamping arms. The clamping arm pair  107  accommodates and temporarily, resiliently secures the pin contact  17  or the socket contact  35 . The shape and spacing of the clamping arms of each clamping arm pair  107  conform to the external shape of the pin contact  17  or the socket contact  35 , i.e. the socket contact holders  103  and the pin contact holders  105  are only suitable for temporarily securing the socket contacts  35  or the pin contacts  17 , respectively.  
         [0031]    The two cutting punches  91 ,  93  exhibit a centre-to-centre distance from one another of 27.5 mm, the centre-to-centre distance is also displayed by mutually adjacent contact holders  103 ,  105 . In this way, the pin contact holders  105  and the two socket contact holders  103  each exhibit a centre-to-centre distance from one another of 55 mm. Other dimensions and spacings, however, are possible.  
         [0032]    To transfer the contacts  103 ,  105  from the respective separating devices  87 ,  89  to the contact transport carriage  101 , the contact transport carriage  101  is displaced such that one of the two pin contact holders  105  is in alignment with the pin cutting punch  91  and/or one of the two socket contact holders  103  is in alignment with the socket cutting punch  93 . By moving the cutting punches  91 ,  93  upwards, the relevant pin contact  17  or socket contact  35  is severed from the strip  79  and is transferred directly into the respective pin contact holder  105  or socket contact holder  103  positioned thereabove. The contacts  103 ,  105  are held firmly thereby by means of the resiliently pretensioned clamping arms  107 .  
         [0033]    Since the pin contact holders  105  conform to the shape of the pin contacts  17  and the socket contact holders  103  conform to the shape of the socket contacts  35 , the pin contacts  17  and the socket contacts  35  may be conveyed into the contact loading station  49  with each working cycle of the welding device  41 . It is possible to transfer as desired two of the pin contacts  17 , two of the socket contacts  35 , or one of the pin contacts  17  and one of the socket contacts  35  into the two pin contact holders  105 , the two socket contact holders  103 , or one of the two pin contact holders  105  and one of the two socket contact holders  103 , respectively. In this way, two of the pin contacts  17 , two of the socket contacts  35 , or one of the pin contacts  17  and one of the socket contacts  35  may be welded as selected to the ends  15  of the optical waveguide  13 . A different contact pairing selection for each working cycle is made possible by programming, so the need for retooling is eliminated.  
         [0034]    After the contact holders  103 ,  105  are loaded with the pin contacts  17  and/or the socket contacts  35  in the loading position illustrated in FIG. 7, the contact transport carriage  101  is displaced into a position in which one of the two contact holders  103 ,  105  is aligned with the laser beam  111 . When the contact transport carriage  101  is displaced, the centre lines of the two contact holders  103 ,  105  are aligned with the centre lines of the ends  15  of the optical waveguide  13  that are positioned by the optical waveguide feed funnels  63 . The ends  15  are introduced into the contacts  17 ,  35  by an optical waveguide feed device (not shown). The respective contacts  17 ,  35  and the respective ends  15  have a predetermined relative axial position such that the desired degree of set-back  31  (FIG. 1) is achieved with a predetermined exacting tolerance.  
         [0035]    After introduction of the ends  15  of the optical waveguide  13  into the contact holders  103 ,  105 , welding is performed. The contact  17 ,  35 , which is located in alignment with the laser  109 , is welded to the end  15  of the optical waveguide  13 . The laser  109  is then moved into alignment with the contact  17 ,  35  held by the other contact holder  103 ,  105 . The contact  17 ,  35  is welded to the end  15  of the optical waveguide  13 . Movement of the laser carriage  113  is controlled with an obliquely extending control channel  115  that is in engagement with a control pin (not shown) that may be moved in a vertical direction by a drive (not shown). The control channel  115  is designed so that the laser carriage  113  may be displaced at least the horizontal distance between the two socket contact holders  103  or the two pin contact holders  105  on the contact transport carriage  101 , i.e., 55 mm in the embodiment illustrated.  
         [0036]    A working cycle of the welding device  41  according to the first embodiment shown in FIGS. 6 through 9 will now be described in greater detail. The electrical control unit  75  is programmed to control whether two of the pin contacts  17  or one of the pin contacts  17  and one of the socket contacts  35  are to be welded to the ends  15  of the optical waveguide  13  during the work cycle. The contact transport carriage  101  is brought into a suitable loading position. If two of the pin contacts  17  are to be welded to the ends  15  of the optical waveguide  13 , the contact transport carriage  101  is moved until the left-hand pin contact holder  105  is aligned with the pin cutting punch  93 . The left-hand pin contact holder  105  is loaded with the pin contact  17  that has been severed from the strip  79 . The contact transport carriage  101  is moved until the right-hand pin contact holder  105  is aligned with the pin cutting punch  93 . A further pin contact  17  is severed from the strip  79  and is transferred into the right-hand pin contact holder  105 . If two of the socket contacts  35  are to be welded to the ends  15  of the optical waveguide  13 , the procedure is the same, except that the left-hand socket contact holder  103  and then the right-hand socket holder  103  are loaded one after the other with a socket contact  35  severed from the strip  79  by the socket cutting punch  91 . If the pin contact  17  is to be welded to the end  15  of the optical waveguide  13  and the socket contact  35  is to be welded to the other end  15  of the optical waveguide  13 , the pin contact  17  is transferred from the strip  79  to the left-hand pin contact holder  105  and the socket contact  35  is transferred from the strip  79  to the left-hand socket contact holder  103 .  
         [0037]    The contact transport carriage  101  is moved into a position wherein the left-hand of the two contact holders  103 ,  105  is aligned with the laser beam  111  and the waveguide feed funnels  63 . The ends  15  of the optical waveguide  13  are introduced through the waveguide feed funnels  63  into the contacts  17 ,  35 . After the ends  15  of the optical waveguide  13  are received in the respective contacts  17 ,  35 , the ends  15  of the two optical waveguide  13  are secured to the respective contacts  17 ,  35  by welding. One of, the two contacts  17 ,  35  is first welded to the respective end  15 . The laser  109  is then displaced by the horizontal carriage  113  into a position corresponding with the other contact  17 ,  35 . The other contact  17 ,  35  is then welded to the respective end  15 . The resulting structural unit  11  is gripped by gripping arms (not shown) and removed from the welding device  41 .  
         [0038]    The second embodiment of the welding device  41  will now be described in greater detail with reference to FIGS. 10 and 11. The welding device  41  of the first embodiment has a maximum working cycle rate, i.e., working cycle frequency. A working cycle rate exceeding this rate may be achieved with the second embodiment of the welding device  41 .  
         [0039]    The welding device  41  of the second embodiment has a laser welding station  57  similar to the first embodiment, but has two contact loading stations  49   a ,  49   b , as shown in FIG. 10. The contact loading stations  49   a ,  49   b  are arranged on opposite sides of the laser welding station  57 . The contact loading stations  49   a ,  49   b  each include the elements and structural units illustrated and described in relation to FIGS. 6 through 9, with the exception that each of the two contact transport carriages  101   a ,  101   b  has only three contact holders. Because each of the contact transport carriages  101   a ,  101   b  has only three contact holders, the optical waveguide  13  is limited to being manufactured with either two pin contacts  17  or one pin contact  17  and one socket contact  35 . The optical waveguide  13  can not be manufactured with socket contacts  35  welded to the ends  15  thereof. Each of the contact transport carriages  101   a ,  101   b  is provided with two pin contact holders  105  and one socket contact holder  103 , such that a structural unit  11  according to FIG. 4 or  5  may be produced with each of the contact transport carriages  101   a ,  101   b.    
         [0040]    As best shown in FIG. 11, the left-hand contact transport carriage  101   a  is positioned on a running rail  117 . In each of the positions between which the laser  109  may be displaced, there is located one of the two feed funnels  63 . Each of the feed funnels  63  includes an upper feed funnel half  119   a  and a lower feed funnel half  119   b . The feed funnel halves  119   a ,  119   b  are formed at lower ends of upper feed funnel plates  121   a ,  121   b , respectively. The two feed funnel plates  121   a ,  121   b  may be moved by means of an upper cylinder drive  123   a  or a lower cylinder drive  123   b  between an open position, in which an end  15  of the optical waveguide  13  may be passed through the respective feed funnel  63 , and a clamping position, in which the resulting structural unit  11  after welding may be clamped. The upper feed funnel plate  121   a  is moved with the interconnection of a toggle lever  125 .  
         [0041]    The working cycle of the welding device  41  according to the second embodiment shown in FIGS. 10 and 11 will now be described in greater detail. As shown in FIG. 10, the loading stations  49   a ,  49   b  operate in a phase-displaced, push-pull manner, such that one of the contact transport carriages  101   a ,  101   b  is located at the loading station  49   a ,  49   b  and the other contact transport carriage  101   a ,  101   b  is located at the laser station  57 . For example, FIG. 10 shows a phase in which the right-hand contact transport carriage  101   b  is located in the right-hand loading position  49   b  and is being loaded with the contacts  17 ,  35 , and the left-hand contact transport carriage  101   a  is located in the laser station  57  and the ends  15  of the optical waveguide  13  are being introduced into the contacts  17 ,  35  and welded thereto. After welding, the resulting structural unit  11  is removed from the welding device  41 , and the left-hand contact transport carriage  101   a  is displaced into the left-hand loading station  49   a  and the right-hand contact transport carriage  101   b  loaded with contacts  17 ,  35  is displaced into the laser station  57 . The ends  15  of the optical waveguide  13  are introduced into the contacts  17 ,  35  held by the right-hand contact transport carriage  101   b  and are welded thereto, while the left-hand contact transport carriage  101   a  is being loaded with the contacts  17 ,  35 .  
         [0042]    In providing the second embodiment of the welding device  41  with two loading stations  49   a ,  49   b , each of the loading stations  49   a ,  49   b  are associated with two contact supply reels  53 ,  55 . A working cycle rate, therefore, may be achieved which is roughly twice that of the first embodiment of the welding device  41  that has only a single loading station  49 .