Pipe connector for a tubular frame bicycle
FIELD OF THE INVENTION 
     My present invention relates to a tubing connector for a tubular frame of a bicycle and, more particularly, to the bottom pedal-crank bearing housing of a bicycle frame. 
     BACKGROUND OF THE INVENTION 
     A tubing connector for a tubular bicycle frame (German Utility Model DE-GM No. 18 34 373) has a plurality of mounting pieces protruding radially outwardly which are secured to the ends of the tubes of the tubing frame. These mounting pieces can be formed by pressing out portions of a wall of the tubing connector. 
     As taught in German Utility model No. 18 34 373 each of these mounting pieces is cylindrical, that is similar in shape to the tubes. 
     However because of this shape a different tubing connector is required for tubing frames having tubes of a different diameter and/or with different frame angles. As a result manufacturing and parts-storage costs are comparatively high. 
     OBJECTS OF THE INVENTION 
     It is an object of my invention to provide an improved tubing connector for a tubular frame of a bicycle. 
     It is also an object of my invention to provide an improved tubing connector for a tubing frame of a bicycle which can be used in a variety of tubing frames having different frame geometries and/or different tubing diameters. 
     SUMMARY OF THE INVENTION 
     These objects and others which will become more apparent hereinafter are attained in a tubing connector for a tubular frame of a bicycle comprising a plurality of mounting pieces protruding radially exteriorly therefrom for the ends of the tubes of the tubing frame connected to or to be connected to the mounting pieces. Each mounting piece is a pressed out portion of the tubing connector. 
     According to my invention each of these mounting pieces is hemispherically shaped. 
     A single tubing connector with hemispherically shaped mounting pieces according to my invention may be used to simplify the manufacture of a variety of different bicycle frames having tubes with a variety of tubing diameters in different angular positions. 
     Advantageously the tubing connector is a bottom bearing housing for the pedal crank bearings and the mounting pieces are pressed out from a wall of the tubing connector. Furthermore the bottom bracket bearing housing has one mounting piece for a saddle tube of the tubing frame, another mounting piece for a lower frame tube and two other mounting pieces for a bifurcated rear member of the tubing frame. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     The above and other objects, features and advantages of my invention will become more readily apparent from the following description, reference being made to the accompanying drawing in which: 
     FIG. 1 is a side elevational view of a tubing connector according to my invention which is also a bottom bracket bearing housing; 
     FIG. 2 is a cross sectional view of the tubing connector of FIG. 1 taken along the section line II--II of FIG. 1; and, 
     FIG. 3 is a bottom plan view of the tubing connector as seen in the direction III of FIG. 1. 
    
    
     SPECIFIC DESCRIPTION 
     The bottom bracket bearing housing 1 for the pedal-crank shaft bearing of a bicycle comprises a first mounting piece 2 for a lower frame tubing 3, a second mounting piece 4 for a saddle tubing 5 and two-third mounting pieces 6 for a rear forked tubing 7 which are hemispherically shaped pressed out portions of the tubing connector wall 11. 
     These hemispherically shaped mounting pieces 2, 4 and 6 are made by deep drawing. The first, second and third mounting pieces 2, 4 and 6 protrude radially toward the exterior from the bottom bracket bearing housing 1. 
     The bottom bracket bearing housing 1 (or tubing connector) is formed from two sheet metal blanks or plate structures whose longitudinal edges when put together with each other are attached to each other by a tongue-and-groove-type joint including the projections 9 and the recesses 10 in which they fit. 
     The ends of the tubes 3, 5 and 7 facing the bottom bracket bearing housing 1 are trimmed at right angles to their longitudinal directions and axes and are attached to the hemispherically shaped mounting pieces 2, 4 and 6 by a circular weld seam. 
     The tubing frame of the not completely shown bicycle comprises the tubes 3, 5 and 7.