Abstract:
The present disclosure relates to a welding system applied to a chassis assembly line for vehicles, and more particularly to a complete floor welding system for various vehicle models. The complete floor welding system for various vehicle models adapted to perform a welding operation after determining and regulating positions of welding spots different according to models of vehicles, comprises: at least one external unit for welding a plurality of parts disposed in a key welding process of a complete floor welding line and having an automatic spot welding gun, the external unit being configured to determine a position according to a model of a vehicle and enter a complete floor from three sides of the complete floor to perform a welding operation; a post structure for installing the external unit; and a controller configured to control the external unit.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims under 35 U.S.C. §119(a) the benefit of Korean Patent Application No. 10-2010-0116621 filed Nov. 23, 2010, the entire contents of which are incorporated herein by reference. 
       BACKGROUND 
       [0002]    (a) Technical Field 
         [0003]    The present disclosure relates to a complete floor welding system applicable to a chassis assembly line for manufacture of vehicles. 
         [0004]    (b) Background Art 
         [0005]    In general, a vehicle manufacturing process involves assembly of numerous parts of a vehicle. Especially, in a chassis assembling process, chassis panels produced via pressing are assembled into chassis as a white body, and floors, doors, trunk lids, hoods, and fenders are then mounted therein. 
         [0006]    Recently, a transferring carriage system has been employed to chassis assembling process for various vehicles to promptly meet the request due to changes in vehicle types. Such a vehicle transferring carriage system transfers chassis panels and parts to a work process corresponding to various types of vehicles to automate the process. 
         [0007]    In a typical carriage system, a jig and parts are moved in between two processes while the parts are clamped to a chassis in a chassis factory. The term “complete floor” herein means a state in which the assembly of front, center, and rear floor parts forming a bottom side of a chassis is completed. 
         [0008]    In addition to the assembly process using a transferring carriage system, a typical vehicle manufacturing process involves a welding process.  FIG. 1  illustrates a conventional complete floor welding line which includes a spot welding process  10  and a key welding process  11  and largely depends on robots. The conventional complete floor welding system has problems. First, it is not easy to redesign an existing welding related program in connection with the behaviors of robots in case where a considerable adjustment of the size and shape of vehicle panels is required for a new vehicle model. Second, the key welding process requires automatic welding guns by using four robots, for which investment costs may be increased and maintaining and repairing the system may become difficult. 
       SUMMARY OF THE DISCLOSURE 
       [0009]    The present invention provides a complete floor welding system for various vehicle models that requires a novel type of complete floor key welding system obtained by combining several external units for welding of parts, wherein each unit includes a three-axis sliding unit configured to determine welding spots according to the model of a vehicle, a part-fixing pin clamp, and an automatic unilateral spot welding gun configured to weld parts, actively complying with various vehicle models and improving the efficiency of the entire welding process. 
         [0010]    In one aspect, the present invention provides a complete floor welding system for various vehicle models adapted to perform a welding operation after determining and regulating positions of welding spots according to models of vehicles, comprising: at least one external unit for welding a plurality of parts disposed in a key welding process of a complete floor welding line and having an automatic spot welding gun, the external unit being configured to determine a position according to a model of a vehicle and enter a complete floor from three sides of the complete floor to perform a welding operation; a post structure for installing the external unit; and a controller configured to control the external unit. 
         [0011]    Preferably, the external unit includes: a three-axis sliding unit having an X-axis linear motion, a Y-axis linear motion, and a Z-axis linear motion and configured to determine a position according to a model of a vehicle; a part-fixing pin clamp installed at an end of the Y-axis linear motion of the three-axis sliding unit and configured to regulation of a position of a part; an automatic gun linear motion installed on the Y-axis linear motion of the three-axis sliding unit; a servo motor installed on one side of the automatic gun linear motion to cross the automatic gun linear motion; and an automatic unilateral spot welding gun installed in the automatic gun linear motion to be moved together with the automatic gun linear motion and configured to perform a welding operation while moving in the X-axis direction. 
         [0012]    The complete floor welding system for various vehicle models according to the present invention has the following advantages. 
         [0013]    First, seal side welding/back panel welding external units are installed in a complete floor key welding process of a complete floor welding line to perform a welding operation such that it unilaterally searches and enters a welding spot according to vehicle models, enabling it to easily comply with the change in vehicle models. 
         [0014]    Second, since a total of six part-welding external units perform welding operation according to the sequential order of welding spots, a welding operation can be effectively performed. In particular, investment cost for equipment can be greatly reduced as compared with that for automatic welding by an existing robot while the management efficiency related to maintenance and repair can be increased. 
         [0015]    Third, six part-welding external units are respectively disposed on three sides of the complete floor, and thus a degree of freedom related to a design of factory layouts can be improved. For example, the space occupancy in layouts can be lowered. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    The above and other features of the present invention will now be described in detail with reference to certain exemplary embodiments thereof illustrated the accompanying drawings which are given hereinbelow by way of illustration only, and thus are not limitative of the present invention, and wherein: 
           [0017]      FIG. 1  is a top view illustrating a conventional complete floor welding line; 
           [0018]      FIG. 2  is a perspective view illustrating a part-welding external unit of a complete floor welding system for various vehicle models according to an embodiment of the present invention; 
           [0019]      FIGS. 3A to 3C  are perspective views illustrating X-axis, Y-axis, and Z-axis operation states of the part-welding external unit of  FIG. 2 , respectively; 
           [0020]      FIG. 4  is a top view illustrating welding wires of the part-welding external unit of the complete floor welding system for various vehicle models according to the embodiment of the present invention; 
           [0021]      FIG. 5  is a top view illustrating a state in which the part-welding external unit of the complete floor welding system for various vehicle models according to the embodiment of the present invention is installed in a welding line; and 
           [0022]      FIG. 6  illustrates a schematic view of operations and welding states of the part-welding external unit of the complete floor welding system for various vehicle models according to the embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0023]    Hereinafter, exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings such that those skilled in the art to which the present invention pertains can easily practice the present invention. 
         [0024]      FIG. 2  is a perspective view illustrating a part-welding external unit of a complete floor welding system for various vehicle models according to an embodiment of the present invention. 
         [0025]    As illustrated in  FIG. 2 , the complete floor welding system includes a part-welding external unit  15  for performing a welding operation, a post structure (not shown) for supporting the part-welding external unit  15 , and a controller (not shown) for controlling the part-welding external unit  15 . The complete floor welding system is adapted to perform a welding operation after determining welding spots, which are different according to vehicle models, and regulating positions of parts. 
         [0026]    In particular, the part-welding external unit  15  is disposed in a key welding process  11  of a complete floor welding line. Unlike the conventional welding system using robots, the part-welding external unit  15  is disposed at three sides of the complete floor and is adapted to weld the welding spots of the parts entering the key welding process  11  unilaterally. 
         [0027]    Such part-welding external units  15 , i.e., seal side and back panel welding external units can be used to various vehicle models. Each of the units includes a three-axis sliding unit  18  configured to determine the position of a complete floor according to vehicle models, a part-fixing pin clamp  19 , and an automatic unilateral spot welding gun  14  configured to weld a seal side part to a floor part, and a back panel part to a floor part. 
         [0028]    A detailed configuration of the part-welding external unit  15  is as follows. The three-axis sliding unit  18  regulates the position of a part (i.e., a complete floor) prior to starting a welding operation. When a complete floor mounted on a complete floor carriage  12  is transferred to the key welding process  11  along a welding line, the three-axis sliding unit  18  is operated in the X-axis, Y-axis, and Z-axis directions to fix the position of the complete floor. To achieve this, the three-axis sliding unit  18  includes an X-axis linear motion  18   a  and a motor  23   a , a Y-axis linear motion  18   b  and a motor  23   b , and a Z-axis linear motion  18   c  and a motor  23   c  that may be moved in the respective directions to determine the position of the complete floor according to vehicle models. 
         [0029]    That is, an X-axis motion guide  25   a  is installed in parallel to the X-axis direction on a front surface of the post structure  16  adapted to support the three-axis sliding unit  18 . The X-axis linear motion  18   a  and the motor  23   a  are coupled to the X-axis motion guide  25   a  so that they can be moved in the X-axis direction along the X-axis motion guide  25   a.    
         [0030]    A Z-axis motion guide  25   c  is installed in parallel to the Z-axis direction on the X-axis linear motion  18   a . The Z-axis linear motion  18   c  and the motor  23   c  are coupled to the Z-axis motion guide  25   c  so that they can be moved in the Z-axis direction along the Z-axis motion guide  25   c.    
         [0031]    A Y-axis motion guide  25   b  is installed parallel to the Y-axis direction on the Z-axis linear motion  18   c . The Y-axis linear motion  18   b  and the motor  23   b  are coupled to the Y-axis motion guide  25   b  so that they can be moved in the Y-axis direction along the Y-axis motion guide  25   b.    
         [0032]    Thus, the three-axis sliding unit  18  is operated as illustrated in  FIGS. 3A to 3C  through the movement of the linear motions to regulate the position of the complete floor using the part-fixing pin clamp  19 . 
         [0033]    For example, as illustrated in  FIG. 3A , if the motor  23   a  is operated, the X-axis linear motion  18   a  is moved in the X-axis direction along the X-axis motion guide  25   a.    
         [0034]    As a result, all of the X-axis linear motion  18   a  and the motor  23   a , the Z-axis linear motion  18   c  and the motor  23   c , the Y-axis linear motion  18   b  and the motor  23   b , the automatic unilateral spot welding gun  14 , and the part-fixing pin clamp  19  are moved in the X-axis direction by the operation of the motor  23   a.    
         [0035]    As illustrated in  FIG. 3B , if the motor  23   c  is operated, the Z-axis linear motion  18   c  is moved in the Z-axis direction along the Z-axis motion guide  25   c.    
         [0036]    As a result, all of the Z-axis linear motion  18   c  and the motor  23   c , the Y-axis linear motion  18   b  and the motor  23   b , the automatic unilateral spot welding gun  14 , and the part-fixing pin clamp  19  are moved in the Z-axis direction. 
         [0037]    As illustrated in  FIG. 3C , if the motor  23   b  is operated, the Y-axis linear motion  18   b  is moved in the Y-axis direction along the Y-axis motion guide  25   b.    
         [0038]    As a result, all of the Y-axis linear motion  18   b  and the motor  23   b , the automatic unilateral spot welding gun  14 , and the part-fixing pin clamp  19  are moved in the Y-axis direction by the operation of the motor  23   b.    
         [0039]    The part-fixing pin clamp  19  is directly inserted into a position regulating hole (not shown) of the complete floor to fix the complete floor and is installed at an end of the Y-axis linear motion  18   b  of the three-axis sliding unit  18  such that the part-fixing pin clamp  19  searches a fixing point to fix the complete floor by the operation of the three-axis sliding unit  18 . 
         [0040]    The automatic unilateral spot welding gun  14  performs a welding operation on welding spots of the complete floor while moving in the X-axis direction. To achieve this, an automatic gun linear motion  21  extending along the X-axis direction is provided on the Y-axis linear motion  18   b  to cross the Y-axis linear motion  18   b  and a serve motor  20  is installed on one side of the automatic gun linear motion  21  to operate the automatic gun linear motion  21 . The automatic unilateral spot welding gun  14  is installed on the automatic gun linear motion  21  to move together such that it performs a welding operation on welding spots while moving in the X-axis direction. 
         [0041]    A support block  26  is installed at an end of the Y-axis linear motion  18   b . The motion guide  21   a  of the automatic gun linear motion  21  is installed long in the support block  26  along the X-axis direction and the automatic unilateral spot welding gun  14  is installed in the motion block  21   b  moving along the motion guide  21   a.    
         [0042]    Accordingly, if the servo motor  20  is operated, the automatic unilateral spot welding gun  14  is moved together with the motion block  21   b  along the X-axis direction to fix its location. 
         [0043]    Thus, if the location of the part-fixing pin clamp  19  is fixed by the operations of the three-axis sliding units  18   a ,  18   b , and  18   c  and the drive motors  23   a ,  23   b , and  23   c , allowing the floor complete to be fixed, the linear motion guide  21  is moved in the X-axis direction by the operation of the servo motor  20 . Then, the automatic unilateral spot welding gun  14  is moved along the X-axis direction, performing welding operations on welded points. 
         [0044]      FIG. 4  is a top view illustrating welding wires of the part-welding external unit of the complete floor welding system for various vehicle models according to the embodiment of the present invention. 
         [0045]      FIG. 4  illustrates an arrangement and a welding diagram of six part-welding external units  15  configured to perform welding operations on the complete floor  100 . 
         [0046]    Three pairs of the part-welding external units  15  are disposed on the periphery, i.e. three sides of the floor complete  100  located in a key welding process  11  and two unilateral welding machines  22   a  and  22   b  control the welding operations of the part-welding external units  15 . Here, each pair of the part-welding external units  15  may be installed on a single frame structure  16 . 
         [0047]    Three part-welding external units  15  are connected to the two unilateral welding machines  22   a  and  22   b  controlled by the controller  17  respectively, and the three external units  15  perform welding operations with predetermined time intervals between the operations thereof. 
         [0048]    A ground  24  is connected to a base of the floor carriage  12  in the form of a clamp in the automatic unilateral welding machines  22   a  and  22   b.    
         [0049]      FIG. 5  is a top view illustrating a state in which the part-welding external unit of the complete floor welding system for various vehicle models according to the embodiment of the present invention is installed in a welding line. 
         [0050]    As illustrated in  FIG. 5 , the complete floor welding system includes a spot welding process  10  and a key welding process  11  and the floor complete carriage  12  is moved along the entire complete floor welding line. 
         [0051]    Automatic welding guns  13  perform welding operations using robots in the spot welding process  10  and the three part-welding external units  15  perform welding operations in the key welding process  11 . 
         [0052]    Accordingly, when a key welding process  11  is performed on a different vehicle model, the part-welding external unit  15  may suitably regulate the position of the complete floor of the vehicle model through the three-axis operation and the automatic unilateral spot welding guns may perform welding operations on welding spots of the vehicle model while moving in the X-axis direction. 
         [0053]      FIG. 6  illustrates a schematic view of operations and welding states of the part-welding external unit of the complete floor welding system for various vehicle models according to the embodiment of the present invention. 
         [0054]    The positions of the part-fixing pin clamps  19   a  and  19   b  are fixed to X 1 , Y 1 , and Z 1  for a vehicle model A and to X 2 , Y 2 , and Z 2  for a vehicle model B by the three-axis operations of the part-welding external units  15   a  and  15   b.    
         [0055]    With the part-fixing pin clamps  19   a  and  19   b  being fixed to the complete floor, the automatic unilateral spot welding guns  14   a  and  14   b  are moved in the X-axis direction according to the sequence of the welding spots such that welding operations are performed at x 1 , y 1 , and z 1  for the vehicle model A and at x 2 , y 2 , and z 2  for the vehicle model B. 
         [0056]    As described above, the complete floor welding system for various vehicle models according to the present invention includes several sets of part-welding external units each of which includes a three-axis sliding unit configured to determine welding spots according to vehicle models, a part-fixing pin clamp, and an automatic unilateral spot welding gun configured to weld parts such that a key welding process can be performed in a complete floor welding line, thereby making the system compatible with various vehicle models and efficiently perform the entire welding process. 
         [0057]    The invention has been described in detail with reference to preferred embodiments thereof. However, it will be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents. Further, many modifications may be made to specific situations and materials without departing from the essence of the invention. Therefore, the present invention is not limited to the detailed description of the preferred embodiments but include all embodiments within the scope of the attached claims.