Abstract:
A method for connecting two components. The method includes heating a deformation region of at least one component part to provide complete heating. The at least one component part is plastically deformed after the complete heating of the deformation region.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a United States National Phase Application of International Application PCT/EP2013/062914 filed Jun. 20, 2013 and claims the benefit of priority under 35 U.S.C. §119 of German Patent Applications DE 10 2012 012 200.4 filed Jun. 21, 2012 and DE 10 2012 013 750.8 filed Jul. 12, 2012, the entire contents of which are incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The present invention relates to a method for joining two components. 
     BACKGROUND OF THE INVENTION 
     In automotive engineering, components are, nowadays, increasingly often bonded with each other by plastic deformation, for example by crimping. At the same time, there is a requirement for these component parts to be designed lighter in weight, i.e. for example thinner-walled or with a small cross-section. Thus, the component parts, particularly during bonding of component parts by plastic deformation, may suffer damage, which may for example impair the safety of the resulting bond. 
     SUMMARY OF THE INVENTION 
     Consequently, the present invention aims to provide a method for joining two component parts, free of the disadvantages of prior art technology. 
     This problem is solved by a method for joining two component parts by plastic deformation, in which at least one component part is heated into its deformation range prior to its plastic deformation, particularly completely heated. 
     The present invention relates to a method joining two component parts by use of plastic deformation. Such processes are known to prior art as, e.g. crimping, flaring, acute-angle bulging or flanging. For that matter, a component part is stuck into another component part, after which one of the component parts is plastically deformed in such a way, that the bond is irreversible. According to the invention, deformation takes place on a previously heated component part, wherein heating preferably occurs in the entire area that is to be deformed. For example, the component part is heated over its entire inner and/or outer circumference, but only locally in the area, in which the bond and/or the deformation is to be realized, i.e. not across the component part&#39;s entire length. This type of heating is particularly preferable for crimping or flanging. Heating may however also only occur in a partial area of the circumference. The subsequent plastic deformation may still occur in the deformation range&#39;s heated condition. Due to the heating, the component part is softer locally and thus allows for deformation, without, for example, any cracks developing. The deformation may however also occur in the, at least partially, cooled-down condition of the component part. In doing so, the heating, and particularly the cooling causes a structural change in the material, so that the component part&#39;s structure is permanently weakened in the deformation range and is thus easier to deform, while no cracks are formed during deformation. Particularly, in the event of a complete heating, the component part&#39;s entire circumference may deform during plastic deformation and no overstraining of the material takes place. The heating is preferably ring-shaped, particularly toroidal or in the form of a segment of a circle. 
     Alternatively, the structure of the component part&#39;s material may also be hardened by the heating and/or cooling. 
     The heating also allows for local stresses to be increased or decreased. 
     The method according to the invention may be used, for example, to create a bearing location for a spring, particularly a torsion spring in a pipe, and/or to bond the spring with the pipe. 
     The method according to the invention preferably involves joining metallic component parts to one another. Preferably, radiation is used as a source of heat, particularly a laser. Preferably, the radiation from a radiation source is diverted via an optical means in such a way, that it strikes the component part&#39;s entire circumference simultaneously, particularly the area which is to be deformed. For that matter, the component part is preferably stationary, i.e. it is not moved during heating, for example rotated. Thus, time is saved and/or heating occurs more evenly. Preferably, the means is a mirror, particularly a ring mirror and/or a cone-shaped mirror and/or a lens. Furthermore, particularly a translucent mirror is employed. The optical means may also be used to achieve, that no radiation is released to the environment. Consequently, containment of the heating zone may be omitted. 
     Additionally or alternatively, the component part is rotated during heating. In the case of radiation being used as a source of heat, heating is preferably contained. 
     The component part&#39;s heating may occur “inline”, particularly during deformation of component parts which have already cooled off, heating may also take place “offline”. 
     According to a further preferred embodiment, heating takes place by induction. 
     Preferably, the component part&#39;s heating is monitored by a sensor, for example a camera, in particular an infrared camera, and/or a pyrometer and the source of heat, particularly the source of radiation and/or the optical means, is regulated via the sensor&#39;s signal. 
     Preferably, the heated component part, after its bonding with the other component part, is cooled in such a way, that subsequently it features desired material properties. For example, cooling results in a structural change. 
     Furthermore, particularly the component part to be heated preferably features various material properties. For example, a material with extraordinary hardness is employed in the bonding area, while the rest of the component part is produced from a material with a lesser hardness. 
     After its heating, the heated component part is deformed, preferably right away, in order to enter a bond with the other component part. 
     The present invention shall be explained in more detail on the basis of the following figures and exemplary embodiments, without the present invention being limited to these. The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings: 
         FIG. 1  is a view showing a bond with crimping and flanging; 
         FIG. 2  is a view showing a bond between a cross beam and a side part of a motor vehicle seat; 
         FIG. 3  is a view showing the component part&#39;s heating; 
         FIG. 4  is a view showing an embodiment of the method according to the invention; and 
         FIG. 5  is a view showing another embodiment of the method according to the invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  shows the bond between a first component part  1 , in this case a pipe, with two secondary component parts  2 ,  3 . Pipe  1  is pushed into the two component parts  2 ,  3 , as illustrated by the blue arrow, and plastically deformed thereafter, so that the pipe is tightly bonded with the component parts  2 ,  3 . The bond between pipe  1  and the component part  2  takes place by crimping  5 , while component part  3  is attached to the pipe&#39;s  1  end by flanging  4 . During crimping or flanging, the pipe  1  is plastically deformed in such a manner, that the component parts  2 ,  3  are bonded with the pipe by form-fit and/or force-fit. While component part  2  is connected to pipe  1  in a manner, in which torque is transferred, pipe  1  may rotate within side part  3 . 
       FIG. 2  shows an application of the bond according to  FIG. 1 . It is recognizable, that pipe  1  is the cross beam of the frame of a seat part of a motor vehicle seat, which is for one bonded with a side part  3  of this frame, and also with a part  2  of the height adjustment of the motor vehicle seat. 
     In  FIG. 3 , the heating—according to the invention—of the pipe, for producing the bond with another component part is shown. For heating, pipe  1  is transported through a heating  7  via a drive  6 , in this case two rollers, in which the pipe is simultaneously and entirely heated in one, in this case in several place(s), which are preferably provided at a distance from one another. The pipe is heated simultaneously and evenly along its entire circumference. Preferably the pipe does not move during its heating. In the present case, heating occurs in the area of circular ring  8 . For this matter, the circular ring  8  on the pipe&#39;s outer circumference is simultaneously and/or evenly heated. Immediately afterwards, deformation of the pipe for producing the crimping or flanging bond takes place. In the present case, the heating of circular ring  8  at the outer circumference of pipe  1  occurs via a laser beam, which is converted via multiple optical means, particularly a cone-shaped mirror, into a ring-shaped radiation, into which the component part to be heated, in this case pipe  1 , is placed, in order to locally and simultaneously heat it in its entire volume. In relation to the cone-shaped mirror, the component part to be heated may be shifted, so that areas may be heated, which are axially spaced. However, in the course of the actual heating of the heating area  8 , the pipe  1  preferably stands still. Furthermore, the apparatus features a camera, by which the pipe&#39;s temperature is measured at the heated circumference. This camera&#39;s signal is used for regulation of the laser. 
     In  FIG. 4  a first embodiment of the process according to the invention is shown. The component part  1  is locally heated to a temperature via a heating means  7 , for example a ring laser, in this case toroidal, which is denoted by reference numeral  8 . Afterwards, the component part  1  is removed from the heating  7 , in this case by a robot, and joined to component parts  2 ,  3  by crimping and flanging. In comparison to a non-heated deformation range, the heating of the deformation range reduces the energy F required for the deformation. Not until then is the component part cooled down to a temperature T 2 . Cooling can take place in such a way, that it results in a structural change in the heated and/or deformed area. 
     In  FIG. 5  an alternative version of the process is shown. After heating, the heated areas are cooled off in a controlled manner in such a way, that the component part&#39;s structure is intentionally weakened locally, in particular by a structural change. Not until after the component part has been cooled down, does the deformation take place, in this case by crimping and flanging, which has already been described above. As a result of the component part&#39;s structure having been intentionally weakened in the bonding area, the deformation may occur more easily and/or free of crack formation. The heating/cooling may occur inline or offline. 
     While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.