Patent Publication Number: US-2019184487-A1

Title: Welding electrode cap

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation-in-part of Application, Ser. No. 15/568,012, filed Oct. 20, 2017 for “IMPROVED WELDING ELECTRODE CAP”, the disclosure which is hereby incorporated by reference, including the drawing. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of Invention 
     This invention relates, in general, to resistance spot welding equipment and, more specifically, to resistance spot welding electrodes. More particularly, the present invention concerns replaceable resistance spot welding electrode caps. Even more particularly, the present invention concerns means and methods for improving the thermal heat dissipation properties of such welding electrode caps. 
     2. Description of Related Art 
     In the above referred to co-pending application there is disclosed an improved electrode tip which provides greater cooling surface for the interior fins thereof by having chamfered ends. 
     The chamfered ends are intended to provide greater surface area for the liquid coolant which is introduced into the interior in association with such finned electrodes. 
     However, one of the deficiencies which is continuously encountered with such electrode tips is their useful life. Because of the heat generated during the robotic welding process the life of these tips, even in spite of the coolant being introduced into the interior thereof, still is not satisfactory. 
     Thus, there exists a need in the art for improving the useful life of these electrode tips. It is to this to which the present invention is directed. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention there is provided an electrode tip having an improved useful life and which, generally, comprises: a domed copper-based electrode tip having a refractory material insert disposed centrally and medially of the tip at the apogee thereof. 
     Since the refractory material has a melting point far in excess of that of the electrode tip the insert serves to increase the useful life thereof. The refractory insert is installed at the apogee of the dome by force-fitting thereinto. 
     In order to effectuate the insert a small opening is formed at the tip of the dome. Thereafter, the refracting material is forced therethrough until it is disposed fully in the interior of the electrode tip with its outer surface being co-planar and circumferentially integrated into the exterior of the tip. 
     For a more complete understanding of the present invention reference is made to the following detailed description and accompany drawing. 
     In the drawing like reference characters refer to like parts throughout the several views, in which: 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A-1C  illustrate, in cross-section, the insertion of a refractory insert into a standard electrode tip in accordance with the present invention; and 
         FIG. 2A-2C  illustrate, in cross-section, the insertion of a refractory insert into a finned electrode. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Now, and with reference to the drawing and, in particular,  FIG. 1 , there is depicted therein an electrode tip  10 . The tip  10  is of the type comprising a substantially cylindrical sidewall  12  with a dome tip  14  integrally formed therewith. The tip has a hollow interior  15  having an entry  16  for receiving an electrode shank  19 . 
     As is known to the skilled artisan a robotic electrode tip  10  is typically formed from copper or a dispersion strengthened copper alloy. Such materials are well known to the skilled artisan. 
     Further, as is known to the skilled artisan such copper or copper-based electrode tips have a melting point of about 1100° F. Under ordinary conditions robotic welding will typically take place at the melting temperature of steel, i.e. about 2750° F. Because of high temperatures at which welding occurs such electrode tips, generally, have a useful life of about 2500 to about 3600 welds. 
     In accordance herewith and as shown in the drawing a medial or central refractory insert  20  is inserted into the interior  15  of the tip and has a length extending from the apogee  21  of the tip of the electrode shank to the interior terminus  22  of the dome  14  of the tip  10  and is imparted with a curvature or other shape such that it is contiguous with the dome of the tip such that there are no discontinuities associated therewith. 
     The refractory material may be of any type which has a melting point in excess of that of the copper or copper alloy. 
     Preferably, among the useful refractory materials are, for example, molybdenum, rhenium, niobium, tungsten, tantalum and the like. The preferred refractory material is tungsten which has a melting point of approximately 6200° F. 
     The tungsten insert can be manufactured by any suitable well known method including powder metallurgical processing. 
     Referring again to the drawing, the refractory insert  20  is inserted into the tip  14  by initially providing a small opening  24  in the dome by any suitable means such as by a punch or the like as well as by drilling in a secondary operation. The insert is, then, force-fitted into the interior of the tip until it reaches with the interior terminus of the electrode top. 
     Any discontinuities are avoided through the force-fitting by having the tungsten insert by being of a diameter slightly larger than that of the pierced or drilled opening into which it is inserted. 
     The insert can be force-fitted through any suitable means including manually with a hammer or through any automatic press or the like. 
     It is to be appreciated herein that the present invention is applicable to any type of copper-based electrode tip be it internally finned such as shown in  FIGS. 2A-2C  or the standard, non-finned electrode of  FIGS. 1A-1C . 
     Having thus described the invention, what is claimed is: 
     INDEX OF REFERENCE NUMERALS 
     Electrode tip  10   
     Sidewall  12   
     Dome  14   
     Interior  15   
     Entry  16   
     Electrode
         Shank  19         

     Insert  20   
     Apogee  21   
     Dome Interior
         Terminus  22         

     Opening  24