Patent Publication Number: US-6670573-B2

Title: Method of joining two members of a vehicle seat

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This is a continuation of International Application No. PCT/EP00/10691, filed Oct. 31, 2000 and designating the U.S. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to a method of joining two members of a vehicle seat, with a first of the members having a projection and the second of the members having a receptacle, and the two members being joined by inserting the projection into the receptacle and then welding. 
     For a known method of the above-described kind, for example, the upper member of a hinge fitting includes two projecting facets in the form of triangular, truncated pyramids, which are inserted into receptacles of an adaptation member of the seat back structure. The upper member and the adaptation member are then joined by electric welding. A disadvantage of this known method is that weld spatters may form, which adversely affects the function of the hinge fitting, so that it must be eliminated as a reject. 
     SUMMARY OF THE INVENTION 
     In accordance with one aspect, the present invention solves the above and other problems by the provision of improvements to the above-described method, by way of which damage to sensitive parts of a vehicle seat is avoided. In accordance with this aspect, a method of joining two members of a vehicle seat includes providing a first member with at least one projection, providing a second member with at least one bore that extends through the second member, and then joining the members. The members are joined by inserting the projection into the bore, and then welding the first and second members together by forming a weld inside the bore while the projection is within the bore. The welding is effected from a side of the second member facing away from the first member. More specifically, the welding is preferably effected by introducing a welding medium, such as a laser beam, into the bore from the side of the second member facing away from the first member. 
     As a result of performing the welding on the side of the second member facing away from the first member, and forming the weld inside a receptacle, which is designed and constructed as the above-mentioned through bore, the risk of weld spatters on the outer side of the parts is lessened, in particular where sensitive components are located. For purposes of substantially avoiding weld spatters, welding occurs preferably within the receptacle, in a location set back from the side facing away from the first member. By inserting a projection into the receptacle, a preliminary positioning occurs, which does not require additional auxiliary means. In addition, forces can be adequately transmitted without requiring that the weld seam include large quantities of material. 
     To provide a reliable cohesion, it is preferred for the weld seam to be positioned inside the receptacle and surround the projection. To obtain an accurately positioned weld seam, it is of advantage to form a channel in which the weld seam is formed inside the receptacle. For example, the channel can be formed by means of bevels, radii, or the like on the projection and/or on the receptacle on the side facing away from the first member and set back from the latter. Preferably, the two members are joined by means of laser welding. This kind of welding exhibits especially little distortion. However, other kinds of welding are also possible. It is possible to accomplish an initial centering, and with that likewise an accurate positioning of the weld seam, in that the projection and the receptacle are provided with the same, for example, circular cross section and little play, and no play if possible. Likewise possible are other cross sections, for example, triangular. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Having thus described the invention in general terms, the invention will now be described in greater detail with reference to a method that is described by way of example with reference to the drawings, in which: 
     FIG. 1 is a sectional view of two members of a vehicle seat, which are to be combined, before their joining; and 
     FIG. 2 is a sectional view corresponding to FIG. 1 during the welding. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In the manufacture of a hinge fitting, two round stubs  3  are pushed out from a fitting member  1 , which is the upper member in the present embodiment, by deforming the, for example, 4 mm thick material. The side of fitting member  1 , from which the round stubs  3  extend, is hereafter named the outer side. 
     The two round stubs  3  have approximately the shape of a circular-cylindrical pin with a diameter of just slightly less than 10 mm. The height of round stubs  3  above the outer side of fitting member  1  amounts to about 2.5 mm. On their outward facing end side, the round stubs  3  include a first bevel  5  with an angle of 45° and a height of about 0.5 mm. Relative to the inner side of fitting member  1 , the round stubs  3  are correspondingly recessed and include on their end side a second bevel  7 , which is formed with the same dimensions parallel offset from the first bevel  5 . 
     A 4 mm thick, flat adaptation member  8 , which is adapted to the special dimensions of the seat component structure or, in the present embodiment, to the seat back structure, includes a circular through bore  10  of a full 10 mm. On the outer side of adaptation member  8 , a third bevel  12  is provided surrounding through bore  10  with a depth of about 1.25 mm and an angle of 45°. This third bevel widens through bore  10  toward the outer side in the shape of a funnel to a diameter of about 12.5 mm. 
     To join fitting member  1  and adaptation member  8 , these two members are combined, and for an initial centering, the round stubs  3  are inserted into the through bores  10  acting as receptacles, with the direction of insertion pointing outward. In their tolerances, the diameters of round stubs  3  and through bores  10  are selected such that the round stubs  3  can be inserted into through bores  10  not only without play, but also without resistance. 
     Once the round stubs  3  are completely inserted into through bores  10 , namely, when the outer side of fitting member  1  lies against the inner side of adaptation member  8 , the first bevel  5  and the third bevel  12  form, in the case of each round stub  3 , a peripheral channel about same, which is set back from the outer side of adaptation member  8  in a plane crosswise to the direction of insertion (FIG.  2 ). In the direction of arrow L, namely opposite to the direction of insertion and from the outer side of adaptation member  8 , a laser beam is directed to this channel from a laser welding device (not shown), and a weld seam is produced inside thereof, which extends about stub  3 , thereby joining fitting member  1  and adaptation member  8 .