Patent Publication Number: US-11643158-B2

Title: Vehicle body assembly system

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to and the benefit of Korean Patent Application No. 10-2020-0092054 filed in the Korean Intellectual Property Office on Jul. 24, 2020, the entire contents of which are incorporated herein by reference. 
     BACKGROUND 
     (a) Field 
     The present disclosure relates to a vehicle body assembly system. More particularly, the present disclosure relates to a vehicle body assembly system capable of assembling vehicle body of multiple vehicle types in a vehicle body assembly line. 
     (b) Description of the Related Art 
     In general, the vehicle body is made in the form of a white body (B.I.W) by assembling various product panels produced in the vehicle body sub-process. 
     The vehicle body includes a floor panel that supports driving units such as an engine and vehicle axle and seats etc., both side panels forming the left and right sides of the vehicle skeleton, a roof panel forming an upper surface of the vehicle skeleton, and components such as a number of cowl panels, a roof rail, a package tray, and a back panel. The assembly of these vehicle body components is done in a process called the main-buck (also known as the body build-up process in the industry). 
     In the main-buck process, the back panel is bonded to the floor panel through the vehicle body assembly system, and then side panels, cowl panels, roof rails, and package trays are welded to assemble them. 
     For example, the body assembly system regulates side panels through side gates, sets the side panels to the floor panel, sets cowl panels, roof rails, and package trays on the side panels, and uses a welding robot to weld the joints of these components. 
     A vehicle body assembly system according to the prior art is provided with a rotation index (commonly referred to as a “four-sided rotating body” in the industry) in which side gates for each vehicle type are respectively installed on four surfaces. The four-sided rotation index rotates in a state where the side panels for each vehicle type are regulated through each side gate, and the side panels of the vehicle type can be positioned on both sides of the floor panel. 
     Therefore, in the prior art, with the correlated components (e.g., cowl panel, roof rail and package tray) positioned on the upper part of the side panel regulated by the side gate of the four-sided rotation index, the upper part of the side panel and the related components, and the lower part of the side panel and the floor panel can be welded using a welding robot. 
     However, in the prior art, since the entire skeleton of the vehicle body is regulated at one time through the side gates for each vehicle type with a four-sided rotation index, it inevitably leads to a high weight and a huge increase in the entire vehicle body assembly system. 
     Furthermore, in the prior art, side gates for each vehicle type are installed on each side of the four-sided rotation index, it is impossible to assemble a car body of more than 5 car types, and to assemble a car body of all car types, it is necessary to additionally install a large, heavy existing facility. 
     The above information disclosed in this Background section is only for enhancement of understanding of the background of the disclosure, and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art. 
     SUMMARY 
     The present disclosure has been made in an effort to provide a vehicle body assembly system capable of assembling vehicle body of multiple vehicle types by separating the vehicle body assembly process into two processes, unlike forming the skeleton of the vehicle body in a single process. 
     A vehicle body assembly system each forming a pre-buck section and a main-buck section set along a transport path of the floor assembly according to an exemplary embodiment of the present disclosure includes a pre-buck unit configured in the pre-buck section to regulate the seal side and the front and rear sides of side assemblies that are different for each vehicle type, and to assemble the side assembly and the floor assembly, and a main-buck unit configured in the main-buck section to regulates the roof portion and the quarter portion of the side assembly assembled to the floor assembly in the pre-buck section, assemble the roof portion, cowl, roof rail and package tray and assemble the quarter portion and the floor assembly. 
     Further, in the vehicle body assembly system according to an exemplary embodiment of the present disclosure, the pre-buck unit may include a pre-buck side jig mounted on a distal end of the arm of the handling robot and regulating the seal side and the front and rear sides of the side assembly, and a first guide post installed to be reciprocally moved in a vehicle width direction on the pre-buck frames on both sides of the transfer path and coupled to the pre-buck side jig through the handling robot. 
     Further, in the vehicle body assembly system according to an exemplary embodiment of the present disclosure, the main-buck unit may include a main-buck side jig mounted on the front end of the arm of the handling robot and regulating a roof portion of the side assembly, a second guide post installed in the main-buck frame on both sides of the transfer path so as to be reciprocally moved along the vehicle width direction, and coupled to the main-buck side jig through the handling robot, and a quarter portion side gate mounted on a mounting frame installed to be reciprocally movable along a vehicle width direction in the main-buck frame separately from the second guide post, and regulating a quarter portion of the side assembly. 
     Further, in the vehicle body assembly system according to an exemplary embodiment of the present disclosure, in the pre-buck section, a width of the floor assembly along the vehicle width direction is measured, and the first guide post may be moved to a set position according to the measured value. 
     Further, in the vehicle body assembly system according to an exemplary embodiment of the present disclosure, in the main-buck section, a distance between the side assemblies positioned on both sides of the floor assembly is measured, and the second guide post and the mounting frame may be moved to a set position according to the measured value. 
     Further, a vehicle body assembly system that forms the pre-buck section and the main-buck section set along the transport path of the floor assembly according to an exemplary embodiment of the present disclosure includes a pre-buck side jig mounted on the handling robot in the pre-buck section and regulating the seal side and the front and rear sides of side assemblies that are different for each vehicle type, a first moving member installed to be reciprocally moved in the vehicle width direction in the pre-buck frames on both sides of the transfer path in the pre-buck section, a pair of first guide posts installed on the first moving member and coupled with the pre-buck side jig through the handling robot, a main-buck side jig mounted on the handling robot in the main-buck section and regulating a roof portion of the side assembly assembled to the floor assembly in the pre-buck section, a second moving member installed in the main-buck frame on both sides of the transfer path to reciprocate along the vehicle width direction in the main-buck section, a pair of second guide posts installed on the second moving member and coupled to the main-buck side jig through the handling robot, a third moving member installed in the main-buck frame to reciprocate along the vehicle width direction separately from the second moving member, and a quarter portion side gate mounted on the third moving member through a mounting frame and regulating a quarter portion of the side assembly. 
     Further, the vehicle body assembly system according to an exemplary embodiment of the present disclosure may further a first sensor installed in the pre-buck section and measuring a width of the floor assembly along a vehicle width direction, and a second sensor installed in the main-buck section and measuring a distance between the side assemblies positioned on both sides of the floor assembly. 
     Further, in the vehicle body assembly system according to an exemplary embodiment of the present disclosure, the pre-buck side jig may be installed on both front and rear sides of the jig frame along the vehicle body transport direction, and include first post coupling portions respectively coupled to the first guide posts. 
     Further, in the vehicle body assembly system according to an exemplary embodiment of the present disclosure, the main-buck side jig may be installed on both front and rear sides of the jig frame along the vehicle body transport direction, and include second post coupling portions respectively coupled to the second guide posts. 
     Further, in the vehicle body assembly system according to an exemplary embodiment of the present disclosure, the first guide post may include first jig coupling portions respectively coupled to the first post coupling portions of the pre-buck side jig. 
     Further, in the vehicle body assembly system according to an exemplary embodiment of the present disclosure, the second guide post may include second jig coupling portions respectively coupled to the second post coupling portions of the main-buck side jig. 
     Further, in the vehicle body assembly system according to an exemplary embodiment of the present disclosure, the first and second post coupling portions may include a coupling block provided on both front and rear sides of the jig frame, and a coupling pin and a guide roller provided on each of the coupling blocks. 
     Further, in the vehicle body assembly system according to an exemplary embodiment of the present disclosure, the first and second jig coupling portions may include a coupling housing having a pin coupling hole for pin coupling with a coupling pin of the coupling block, and a jig clamp installed on the first and second guide posts and clamping the coupling block coupled to the coupling housing. 
     Further, in the vehicle body assembly system according to an exemplary embodiment of the present disclosure, the main-buck side jig may include a first coupling rod fixedly installed along a vehicle width direction to a jig frame positioned at one side of the transport path in the main-buck section and having a coupling protrusion at a free end, and a second coupling rod fixedly installed along the vehicle width direction in a jig frame positioned on the other side of the transfer path in the main-buck section, and forming a coupling groove that engages the coupling protrusion of the first coupling rod at a free end. 
     Further, in the vehicle body assembly system according to an exemplary embodiment of the present disclosure, the quarter portion side gate may include a gate frame provided so as to be mountable to the front end of the arm of the handling robot through the robot coupling portion and fixedly installed on the mounting frame, and at least one fastening portion provided in the gate frame. 
     Further, in the vehicle body assembly system according to an exemplary embodiment of the present disclosure, the mounting frame may include a docking coupling portion coupled to the lower end of the gate frame, and a mounting portion mutually fastened with the fastening portion of the quarter portion side gate. 
     Further, a vehicle body assembly system that forms the pre-buck section and the main-buck section set along the transport path of the floor assembly according to an exemplary embodiment of the present disclosure includes a pre-buck side jig mounted on the handling robot in the pre-buck section and regulating the seal side and the front and rear sides of side assemblies that are different for each vehicle type, a pair of first guide posts installed on a first moving member reciprocating in the vehicle width direction to the pre-buck frames on both sides of the transfer path in the pre-buck section, and coupled with the pre-buck side jig through the handling robot, a main-buck side jig mounted on the handling robot in the main-buck section and regulating a roof portion of the side assembly assembled to the floor assembly in the pre-buck section, a pair of second guide posts installed on second moving members reciprocating along the vehicle width direction in the main-buck frames on both sides of the transfer path in the main-buck section, and coupled to the main-buck side jig through the handling robot, a quarter portion side gate mounted on the main-buck frame separately from the second moving member through a mounting frame to a third moving member reciprocating along a vehicle width direction, and regulating a quarter portion of the side assembly, and a position correction unit installed in the pre-buck frame, the main-buck frame, and the first, second, and third moving members so as to be in mutually stopping contact, and correcting a stopping position of the first, second, and third moving members with respect to the pre-buck frame and the main-buck frame. 
     Further, in the vehicle body assembly system according to an exemplary embodiment of the present disclosure, the position correction unit may include a fixing stopper having a inclined surface inclined toward one side based on a vehicle body transport direction, and fixedly installed on the first, second, and third moving members, and a movable stopper that has a inclined surface inclined toward the other side, is provided to be in contact with the fixing stopper, and is installed on the pre-buck frame and the main-buck frame to be moved back and forth along the vehicle body transport direction by a driving source. 
     Further, in the vehicle body assembly system according to an exemplary embodiment of the present disclosure, the driving source may include a linear module having a movable block linearly reciprocating along the vehicle body transport direction through a linear guide and installed in the pre-buck frame and the main-buck frame. 
     Further, in the vehicle body assembly system according to an exemplary embodiment of the present disclosure, the first, second, and third moving members may be respectively connected to operating cylinders provided in the pre-buck frame and the main-buck frame. 
     Further, the vehicle body assembly system according to an exemplary embodiment of the present disclosure may further include a first storage unit installed in the pre-buck section and storing the pre-buck side jigs different for each vehicle type, a second storage unit installed in the main-buck section and storing the main-buck side jigs different for each vehicle type, and a third storage unit installed in the main-buck section and storing side gates of the quarter unit. 
     Further, the vehicle body assembly system according to an exemplary embodiment of the present disclosure may further include first welding robots installed in the pre-buck section and welding the side assembly and the floor assembly, and second welding robots installed in the main-buck section, welding the side assembly and the floor assembly, and welding the side assembly and the cowl, the roof rail, and the package tray. 
     Exemplary embodiments of the present disclosure enable flexible production of multiple vehicle types, reduce equipment preparation time, achieve weight reduction and simplification of the entire equipment, and reduce investment costs at the initial stage and when adding vehicle types. 
     In addition, effects that can be obtained or predicted by the exemplary embodiments of the present disclosure will be disclosed directly or implicitly in the detailed description of the exemplary embodiments of the present disclosure. That is, various effects predicted according to an embodiment of the present disclosure will be disclosed within a detailed description to be described later. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The drawings are provided for reference in describing exemplary embodiments of the present disclosure and the spirit of the present disclosure should not be construed only by the accompanying drawings. 
         FIGS.  1  and  2    are diagrams schematically showing a vehicle body assembly system according to an exemplary embodiment of the present disclosure. 
         FIG.  3    is a plan view showing a vehicle body assembly system according to an exemplary embodiment of the present disclosure. 
         FIG.  4    is a combined perspective view showing a pre-buck unit applied to a vehicle body assembly system according to an exemplary embodiment of the present disclosure. 
         FIG.  5    is a partial exploded perspective view illustrating a pre-buck unit applied to a vehicle body assembly system according to an exemplary embodiment of the present disclosure. 
         FIG.  6    is a view showing a first post coupling portion and a first jig coupling portion of a pre-buck unit applied to a vehicle body assembly system according to an exemplary embodiment of the present disclosure. 
         FIG.  7    is a diagram illustrating a position correction unit of a pre-buck unit and a main-buck unit applied to a vehicle body assembly system according to an exemplary embodiment of the present disclosure. 
         FIGS.  8  and  9    are perspective views illustrating a main-buck unit applied to a vehicle body assembly system according to an exemplary embodiment of the present disclosure. 
         FIG.  10    is a partial exploded perspective view illustrating a main-buck unit applied to a vehicle body assembly system according to an exemplary embodiment of the present disclosure. 
         FIG.  11    is a diagram illustrating a second post coupling portion and a second jig coupling portion of a main-buck unit applied to a vehicle body assembly system according to an exemplary embodiment of the present disclosure. 
         FIG.  12    is a diagram illustrating a structure of mounting a side gate of a quarter portion of a main-buck unit applied to a vehicle body assembly system according to an exemplary embodiment of the present disclosure. 
       
         
           
             
                 
               
                 
                     
                 
                 
                   &lt;Description of symbols&gt; 
                 
                 
                     
                 
               
              
                 
                     
                 
              
             
             
                 
                 
              
                 
                   1: carriage line 
                   2: floor assembly 
                 
                 
                   3: side assembly 
                   4a: seal side 
                 
                 
                   4b: front side 
                   4c: rear side 
                 
                 
                   4d: roof portion 
                   4e: quarter portion 
                 
                 
                   7: cowl 
                   8a: front roof rail 
                 
                 
                   8b: rear roof rail 
                   9: package tray 
                 
                 
                   10: CRP carriage 
                   11: first welding robot 
                 
                 
                   12: second welding robot 
                   20: pre-buck section 
                 
                 
                   21: pre-buck frame 
                   50: main-buck section 
                 
                 
                   51: main-buck frame 
                   100: vehicle body assemble system 
                 
                 
                   101: first handling robot 
                   102: second handling robot 
                 
                 
                   110: pre-buck side jig 
                   111: first jig frame 
                 
                 
                   112: first robot mount portion 
                   113: first clamper 
                 
                 
                   121: first post coupling portion 
                   123: first coupling block 
                 
                 
                   125: first coupling pin 
                   127: first guide roller 
                 
                 
                   150: first moving member 
                   151: first driving source 
                 
                 
                   153: first operating cylinder 
                   170: first guide post 
                 
                 
                   171: first post frame 
                   173: first jig coupling portion 
                 
                 
                   175: first coupling housing 
                   177: first jig clamp 
                 
                 
                   179: first pin coupling hole 
                   200: pre-buck unit 
                 
                 
                   210: first sensor 
                   230: first position correction unit 
                 
                 
                   231: first fixing stopper 
                   233: first inclined surface 
                 
                 
                   241, first movable stopper 
                   243: second inclined surface 
                 
                 
                   245: second driving source 
                   247: first linear module 
                 
                 
                   251, 751, 771: linear motor 
                   253, 753, 773: linear guide 
                 
                 
                   255, 755, 775: moving block 
                   310: first storage unit 
                 
                 
                   500: main-buck unit 
                   510: main-buck side jig 
                 
                 
                   511: second jig frame 
                   512: second robot mount portion 
                 
                 
                   513: second clamper 
                   521: second post coupling portion 
                 
                 
                   523: second coupling block 
                   525: second coupling pin 
                 
                 
                   527: second guide roller 
                   531: first coupling rod 
                 
                 
                   532: second coupling rod 
                   533: coupling protrusion 
                 
                 
                   534: coupling groove 
                   550: second moving member 
                 
                 
                   551: third driving source 
                   553: second operation cylinder 
                 
                 
                   570: second guide post 
                   571: second post frame 
                 
                 
                   573: second jig coupling portion 
                   575: second coupling housing 
                 
                 
                   577: second jig clamp 
                   579: second pin coupling hole 
                 
                 
                   610: third moving member 
                   611: fourth driving source 
                 
                 
                   613: third operating cylinder 
                   630: mounting portion 
                 
                 
                   631: docking coupling portion 
                   640: mount frame 
                 
                 
                   650: quarter portion side gate 
                   651: gate frame 
                 
                 
                   652: robot coupling portion 
                   653: engage portion 
                 
                 
                   655: third clamper 
                   710: second sensor 
                 
                 
                   730, 750: second position correction 
                 
                 
                   unit, third position correction unit 
                 
                 
                   731, 751: second fixing stopper, 
                 
                 
                   third fixing stopper 
                 
                 
                   733, 753: third inclined surface, 
                 
                 
                   fourth inclined surface 
                 
                 
                   741, 761: second movable stopper, 
                 
                 
                   third movable stopper 
                 
                 
                   743, 763: fifth inclined surface, 
                 
                 
                   sixth inclined surface 
                 
                 
                   745, 765: fifth driving source, 
                 
                 
                   sixth driving source 
                 
                 
                   747, 767: second linear module, 
                 
                 
                   third linear module 
                 
                 
                   820: second storage unit 
                   830: third storage unit 
                 
                 
                     
                 
              
             
           
         
       
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, the present disclosure will be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the disclosure are shown. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present disclosure. 
     In order to clarify a description of the present disclosure, parts not related to the description are omitted, and the same reference numbers are used throughout the drawings to refer to the same or like parts. Furthermore, a description of parts which may be easily understood by those skilled in the art is omitted. 
     The size and thickness of each of elements shown in the drawings are randomly illustrated for convenience of description and thus the present disclosure is not limited to those shown in the drawings. In the drawings, a thickness is enlarged in order to clearly show several parts and areas. 
     Furthermore, in the following detailed description, terms denoting the names of elements, such as the first and the second, are provided to distinguish the elements from each other because the elements have the same construction, and the elements are not limited to corresponding order in the following description. 
     In the entire specification, unless explicitly described to the contrary, the word “comprise” and variations, such as “comprises” or “comprising”, will be understood to imply the inclusion of stated elements but not the exclusion of any other elements. 
     Furthermore, each of terms, such as ‘ . . . unit”, “ . . . means’, ‘ . . . part’, and ‘ . . . member’ described in the specification, mean a unit of a comprehensive element that performs at least one function or operation. 
       FIGS.  1  and  2    are diagrams schematically showing a vehicle body assembly system according to an exemplary embodiment of the present disclosure. 
     Referring to  FIG.  1    to  FIG.  3   , a vehicle body assembly system according to an exemplary embodiment of the present disclosure can be applied to a body assembly line that regulates and welds vehicle body assembly components transported from a sub-assembly line of a body factory with a jig, and completes the skeleton of a body white body (B.I.W). 
     The body assembly line process includes a step of assembling a floor assembly that becomes the basis of a vehicle body, a step of assembling a side assembly, which is a wall component of a vehicle body, with a floor assembly, and a step of assembling a cowl, roof rail, and package tray to the side assembly. 
     Here, a process of assembling a side assembly to a floor assembly and assembling a cowl, a roof rail, and a package tray to the side assembly is also referred to as a buck process in the industry. 
     This buck process is a process of fixing a welding fixture through a jig, swinging, rotating, and shifting the welding fixture, and assembling an under body assembly, a side body assembly, and a roof body assembly. 
     In the vehicle body assembly system according to an exemplary embodiment of the present disclosure, a robot can be applied as a spot welding facility in the buck process of assembling floor assemblies, left and right side assemblies, cowl, front/rear roof rails and package trays in the body assembly line. 
     Furthermore, in the vehicle body assembly system  100  according to the embodiment of the present disclosure, based on the floor assembly  2  transported along the transport path set through the carriage line  1 , the side assembly  3  may be assembled on both sides of the floor assembly  2 . In addition, the vehicle body assembly system  100  may assemble the cowl  7 , the front roof rail  8   a , the rear roof rail  8   b , and the package tray  9  to the side assembly  3 . Here, the cowl  7 , the front roof rail  8   a , the rear roof rail  8   b , and the package tray  9  may be defined as CRP components  7 ,  8   a ,  8   b , and  9 . 
     In an exemplary embodiment of the present disclosure, the conveying direction of the floor assembly  2  is defined as the vehicle body conveying direction (more, the front-rear direction). In the industry, the vehicle body transport direction is called the T direction, the vehicle width direction is called the L direction, and the height direction of the vehicle body is called the H direction. 
     However, in an exemplary embodiment of the present disclosure, instead of setting the LTH direction as the reference direction as described above, the components are described below by setting the vehicle body transport direction, the vehicle width direction, and the height direction. 
     Furthermore, the stage in the following may be defined as either end (one/one end or the other/one end), or may be defined as a certain portion including the end (one/one end or the other/one end). 
     The vehicle body assembly system  100  according to an exemplary embodiment of the present disclosure can assemble multiple vehicle types by separating the vehicle body assembly process into two processes, unlike forming the skeleton of the vehicle body in a single process, and has a structure capable of reducing the weight of the entire facility. 
     To this end, in the vehicle body assembly system  100  according to the exemplary embodiment of the present disclosure, a pre-buck section  20  and a main-buck section  50  divided along the transfer path of the carriage line  1  are set. 
     In addition, the vehicle body assembly system  100  according to an exemplary embodiment of the present disclosure basically includes a pre-buck unit  200  configured in the pre-buck section  20  and a main-buck unit  500  configured in the main-buck section  50 . 
     The pre-buck unit  200  and the main-buck unit  500  as described above can be in one frame in each pre-buck section  20  and the main-buck section  50 , or can be divided into each frame. 
     This frame is for supporting the components to be described below, and includes various brackets, blocks, plates, housings, covers, collars, and other accessory elements. 
     However, since the sub-elements are for installing each of the constituent elements in the frame, the above-described sub-elements are collectively referred to as a frame except for exceptional cases in the exemplary embodiment of the present disclosure. 
     In an exemplary embodiment of the present disclosure, the pre-buck unit  200  regulates the lower sill side  4   a  and the front and rear sides  4   b  and  4   c  of the side assembly  3 , which are different for each vehicle type in the pre-buck section  20 . This is for assembling the side assembly  3  to the floor assembly  2 . 
     Further, the pre-buck unit  200  can weld the seal side  4   a  and the front and rear sides  4   b  and  4   c  of the side assembly  3  through the first welding robot  11  installed in the pre-buck section  20 . 
     The configuration of the pre-buck unit  200  is configured on both sides of the transfer path of the carriage line  1  in the pre-buck section  20 , and the configuration will be described in more detail below. 
     In an exemplary embodiment of the present disclosure, the main-buck unit  500  regulates the roof portion  4   d  and the quarter portion  4   e  of the side assembly  3  assembled to the floor assembly  2  in the pre-buck section  20 , assembles the roof portion  4   d  and the cowl  7 , the front roof rail  8   a , the rear roof rail  8   b , and the package tray  9 , and assembles the quarter portion  4   e  and the floor assembly  2 . 
     Here, the main-buck unit  500  may assemble the cowl  7 , the front roof rail  8   a , the rear roof rail  8   b , and the package tray  9  as CRP components regulated by the CRP carriage  10  to the side assembly  3 . 
     Furthermore, the main-buck unit  500  can weld the roof portion  4   d  and the cowl  7  of the side assembly  3 , the front roof rail  8   a , the rear roof rail  8   b , and the package tray  9  through the second welding robot  12  installed in the main-buck section  50 , and can weld the quarter portion  4   e  of the side assembly  3  and the floor assembly  2 . 
     The configuration of the main-buck unit  500  is configured on both sides of the transfer path of the carriage line  1  in the main-buck section  50 , and the configuration will be described in more detail below. 
       FIG.  4    is a combined perspective view showing a pre-buck unit applied to a vehicle body assembly system according to an exemplary embodiment of the present disclosure, and  FIG.  5    is a partial exploded perspective view illustrating a pre-buck unit applied to a vehicle body assembly system according to an exemplary embodiment of the present disclosure. 
     Referring to  FIG.  1    to  FIG.  5   , the pre-buck unit  200  according to an exemplary embodiment of the present disclosure regulates the lower seal side  4   a  and the front and rear sides  4   b  and  4   c  of the side assembly  3 , and includes a structure in which the side assembly  3  can be accurately matched to the set positions on both sides of the floor assembly  2 . 
     Furthermore, the pre-buck unit  200  has a structure capable of minimizing the distribution of the position (assembly) of the side assembly  3  to be matched to both sides of the floor assembly  2 . Further, the pre-buck unit  200  may weld the lower seal side  4   a  and the front and rear sides  4   b  and  4   c  of the side assembly  3  to both sides of the floor assembly  2 . 
     To this end, the pre-buck unit  200  according to an exemplary embodiment of the present disclosure includes a pre-buck side jig  110 , a first moving member  150 , a first guide post  170 , a first sensor  210 , and a first position correction unit  230 . 
     In an exemplary embodiment of the present disclosure, the pre-buck side jig  110  regulates the seal side  4   a  and the front and rear sides  4   b  and  4   c  of the side assembly  3  to be matched to both sides of the floor assembly  2 . 
     The pre-buck side jig  110  may regulate (clamp) the seal side  4   a  and the front and rear sides  4   b  and  4   c  of the side assembly  3  arranged in a separate alignment jig. The pre-buck side jig  110  may be mounted on the front end of the arm of the first handling robot  101  in the pre-buck section  20 . 
     The pre-buck side jig  110  includes a first jig frame  111 , first clampers  113 , and a first post coupling portion  121 . 
     The first jig frame  111  is mounted on the arm tip of the first handling robot  101  through the first robot mounting portion  112 . 
     The first clamper  113  clamps the seal side  4   a  and the front and rear sides  4   b  and  4   c  of the side assembly  3  different for each vehicle type, and is installed in plurality on the first jig frame  111 . The first clamper  113  is provided as a clamper of a known technology capable of clamping or unclamping through a clamp cylinder. In this case, the first clamper  113  may be installed to reciprocate in a direction set with respect to the first jig frame  111  according to a vehicle type. 
     In addition, the first post coupling portion  121  couples the first jig frame  111  and the first guide post  170  to be described later, and is provided on both front and rear sides of the first jig frame  111  along the vehicle body transport direction. That is, the pre-buck side jig  110  may be coupled to the first guide post  170  through the first post coupling portion  121 . 
     The first post coupling portion  121  includes a first coupling block  123 , a first coupling pin  125 , and first guide rollers  127 , as shown in  FIG.  6   . The first coupling block  123  is provided on both front and rear sides of the first jig frame  111 . 
     The first coupling pin  125  is provided on the side facing the transport path of the first coupling block  123 . In addition, the first guide rollers  127  are rotatably installed on both front and rear sides of the first coupling block  123  along the vehicle body transport direction. 
     Referring to  FIG.  4    and  FIG.  5   , in an exemplary embodiment of the present disclosure, the first moving member  150  is installed in the pre-buck frame  21  on both sides of the transfer path in the pre-buck section  20 , and installed to be reciprocally moved in the vehicle width direction with respect to both sides of the floor assembly  2 . 
     For example, the first moving member  150  is provided in a plate shape, and is installed to be reciprocally moved in the vehicle width direction by the first driving source  151  on the upper surface of the pre-buck frame  21 . 
     Here, the first driving source  151  includes a first actuating cylinder  153  fixedly installed on the pre-buck frame  21  and having an actuating rod actuated forward and backward by pneumatic pressure. The first actuating cylinder  153  is connected to the first moving member  150  through an actuating rod. 
     Referring to  FIG.  4    and  FIG.  5   , in an exemplary embodiment of the present disclosure, the first guide post  170  is coupled to the pre-buck side jig  110  through the first handling robot  101  and is fixedly installed on the first moving member  150 . 
     The first guide posts  170  are installed as a pair to be fixed to the front and rear sides of the first moving member  150  along the vehicle body transport direction. The first guide post  170  includes a first post frame  171  and a first jig coupling portion  173  provided in the first post frame  171 . 
     The first post frame  171  is installed to be fixed to the first moving member  150  in the vertical direction. The first jig coupling portion  173  is coupled with the first post coupling portion  121  of the pre-buck side jig  110 , and is installed on the upper end of the first post frame  171  in correspondence with the first post coupling portion  121 . 
     In the above, the first jig coupling portion  173  includes a first coupling housing  175  and a first jig clamp  177  as shown in  FIG.  6   . The first coupling housing  175  is fixed to the upper end of the first post frame  171 . 
     The first coupling housing  175  supports the first guide roller  127  of the first post coupling portion  121  and is coupled to the first coupling block  123  of the first post coupling portion  121 . The first coupling housing  175  has a first pin coupling hole  179  that is pin-coupled with the first coupling pin  125  of the first coupling block  123 . 
     The first jig clamp  177  connects the first coupling block  123  coupled to the first pin coupling hole  179  of the first coupling housing  175  through the first coupling pin  125  to the first coupling housing  175 . 
     The first jig clamp  177  is fixedly installed on the first post frame  171 . The first jig clamp  177  is provided as a clamper of a known technology for clamping or unclamping the first coupling block  123  through a clamp cylinder. 
     Referring to  FIG.  3   , in an exemplary embodiment of the present disclosure, the width along the vehicle width direction of the floor assembly  2  is measured in the pre-buck section  20 , and according to the measured value, the first guide post  170  may be moved to a set position along the vehicle width direction through the first moving member  150 . 
     For this, in an exemplary embodiment of the present disclosure, the first sensor  210  installed in the pre-buck section  20  is included. The first sensor  210  may include a known technology vision sensor. The first sensor  210  measures the width of the floor assembly  2  along the vehicle width direction and outputs the measured value to a controller (not shown in the drawing). 
     Referring to  FIG.  3    to  FIG.  5   , the first position correction unit  230  according to an exemplary embodiment of the present disclosure can correct the position of the first moving member  150  in the vehicle width direction with respect to the pre-buck frame  21  according to the measured value of the first sensor  210 . 
     The first position correction unit  230  is installed to be in stopping contact with the pre-buck frame  21  and the first moving member  150 . As shown in  FIG.  7   , the first position correction unit  230  includes a first fixed stopper  231  and a first movable stopper  241 . 
     The first fixing stopper  231  is fixed to the first moving member  150 . The first fixing stopper  231  is provided in a plate shape. The first fixed stopper  231  has a first inclined surface  233  inclined toward one side with respect to the vehicle body transport direction. 
     The first movable stopper  241  is installed in the pre-buck frame  21  to be moved back and forth along the vehicle body transport direction in correspondence with the first fixed stopper  231 . The first movable stopper  241  has a plate shape and is provided to be in surface contact with the first fixed stopper  231 . The first movable stopper  241  is formed to be inclined on the other side with respect to the vehicle body transport direction, and has a second gradient surface  243  that is capable of surface contact with the first gradient surface  233  of the first fixed stopper  231 . 
     In the above, the first movable stopper  241  moves back and forth along the vehicle body transport direction by the second driving source  245 . The second driving source  245  includes a first linear module  247  installed in the pre-buck frame  21 . 
     The first linear module  247  includes a linear motor  251  and a moving block  255  that linearly reciprocates along a vehicle body transport direction through a linear guide  253  by driving the linear motor  251 . Here, the first movable stopper  241  is fixedly installed on the moving block  255 . 
     Meanwhile, referring to  FIG.  1    and  FIG.  2   , the pre-buck unit  200  according to an exemplary embodiment of the present disclosure as described above includes the first welding robots  11  and the first storage unit  310  as mentioned above. 
     The first welding robots  11  are installed in the pre-buck section  20 , and the lower seal side  4   a  of the side assembly  3  and the front and rear sides  4   b  and  4   c  are welded to both sides of the floor assembly  2 . 
     In addition, the first storage unit  310  is installed in the pre-buck section  20 , and may store different pre-buck side jigs  110  for each vehicle type. The pre-buck side jigs  110  stored in the first storage unit  310  may be pulled out by the first handling robot  101 . 
       FIGS.  8  and  9    are perspective views illustrating a main-buck unit applied to a vehicle body assembly system according to an exemplary embodiment of the present disclosure, and  FIG.  10    is a partial exploded perspective view illustrating a main-buck unit applied to a vehicle body assembly system according to an exemplary embodiment of the present disclosure. 
     Referring to  FIG.  8    to  FIG.  10    with  FIG.  1    to  FIG.  3   , the main-buck unit  500  according to an exemplary embodiment of the present disclosure includes a structure capable of regulating the roof portion  4   d  and the quarter portion  4   e  of the side assembly  3  assembled to the floor assembly  2  by the pre-buck unit  200  in the pre-buck section  20 . 
     In addition, the main-buck unit  500  includes a structure that can accurately match the cowl  7 , the front roof rail  8   a , the rear roof rail  8   b , and the package tray  9  as CRP components regulated by the RP truck  10  to the set position of the side assembly  3 . 
     Further, the main-buck unit  500  has a structure capable of minimizing the distribution of the position (assembly) of the side assembly  3  to be matched with the CP component. 
     Furthermore, the main-buck unit  500  can weld the roof portion of the side assembly  3 , cowl  7 , front roof rail  8   a , rear roof rail  8   b , and package tray  9 , and can weld the quarter portion  4   e  of the side assembly  3  and the floor assembly  2 . 
     For this, the main-buck unit  500  according to an exemplary embodiment of the present disclosure includes a main-buck side jig  510 , a second moving member  550 , a second guide post  570 , a third moving member  610 , a mounting frame  640 , and a quarter portion side gate  650 , a second sensor  710 , and second and third position correction units  730  and  750 . 
     In an exemplary embodiment of the present disclosure, the main-buck side jig  510  regulates the roof portions  4   d  on both sides of the side assembly  3  assembled on the floor assembly  2  in the pre-buck section  20 . 
     The main-buck side jig  510  may be mounted on the arm tip of the second handling robot  102  in the main-buck section  50 . The main-buck side jig  510  includes a second jig frame  511 , second clampers  513 , a second post coupling portion  521 , a first coupling rod  531 , and a second coupling rod  532 . 
     The second jig frame  511  is mounted on the arm tip of the second handling robot  102  through the second robot mounting portion  512 . 
     The second clampers  513  clamp the roof portion  4   d  of the side assembly  3  that is different for each vehicle type, and are installed in a plurality of the second jig frame  511 . The second clamper  513  is provided as a clamper of a known technology capable of clamping or unclamping the roof portion  4   d  through a clamp cylinder. At this time, the second clamper  513  may be installed to reciprocate in a direction set with respect to the second jig frame  511  according to a vehicle type. 
     The second post coupling portions  521  are for coupling the second jig frame  511  and the second guide post  570  to be described later, and are installed on both front and rear sides of the second jig frame  511  along the vehicle body transport direction. That is, the main-buck side jig  510  may be coupled to the second guide post  570  through the second post coupling portion  521 . 
     The second post coupling portion  521  includes a second coupling block  523 , a second coupling pin  525 , and second guide rollers  527 , as shown in  FIG.  11   . The second coupling blocks  523  are provided on both front and rear sides of the second jig frame  511 . 
     The second coupling pin  525  is provided on the side of the second coupling block  523  facing the transport path. In addition, the second guide rollers  527  are rotatably installed on both front and rear sides of the second coupling block  523  along the vehicle body transport direction. 
     Referring to  FIG.  8    to  FIG.  10   , the first coupling rod  531  and the second coupling rod  532  maintain the absolute width (width in the vehicle width direction) between the two side assemblies  3  regulated by the second clampers  513 , and this is to minimize the dispersion between the both side assembly  3 . 
     The first coupling rod  531  is fixedly installed along the vehicle width direction in the second jig frame  511  positioned on one side of the transport path in the main-buck section  50 . The first coupling rod  531  has a coupling protrusion  533  at a free end. 
     The second coupling rod  532  is fixedly installed in the second jig frame  511  located on the other side of the transport path in the main-buck section  50  along the vehicle width direction. The second coupling rod  532  has a coupling groove  534  coupled to the coupling protrusion  533  of the first coupling rod  531  at a free end. 
     Referring to  FIG.  8    to  FIG.  10   , in an exemplary embodiment of the present disclosure, the second moving members  550  are respectively installed on the main-buck frames  51  on both sides of the transfer path in the main-buck section  50 , and is installed to be reciprocally moved in the vehicle width direction with respect to both side assemblies  3  of the floor assembly  2 . 
     For example, the second moving member  550  is provided in a plate shape, and is installed to be reciprocally moved in the vehicle width direction by a third driving source  551  on the upper surface of the main-buck frame  51 . 
     Here, the third driving source  551  includes a second actuating cylinder  553  fixedly installed on the main-buck frame  51  and having an actuating rod actuated forward and backward by pneumatic pressure. The second actuating cylinder  553  is connected to the second moving member  550  through an actuating rod. 
     Referring to  FIG.  8    to  FIG.  10   , in an exemplary embodiment of the present disclosure, the second guide post  570  is coupled to the main-buck side jig  510  through the second handling robot  102  and is fixedly installed on the second moving member  550 . 
     The second guide posts  570  are installed as a pair to be fixed to each of the front and rear sides of the second moving member  550  along the vehicle body transport direction. The second guide posts  570  each include a second post frame  571  and a second jig coupling portion  573  provided in the second post frame  571 . 
     The second post frame  571  is installed to be fixed to the second moving member  550  in the vertical direction. The second jig coupling portion  573  is coupled with the second post coupling portion  521  of the main-buck side jig  510 , and is installed on the upper end of the second post frame  571  corresponding to the second post coupling portion  521 . 
     In the above, the second jig coupling portion  573  includes a second coupling housing  575  and a second jig clamp  577  as shown in  FIG.  11   . The second coupling housing  575  is fixed to the upper end of the second post frame  571 . 
     The second coupling housing  575  supports the second guide roller  527  of the second post coupling portion  521  and is coupled to the second coupling block  523  of the second post coupling portion  521 . The second coupling housing  575  has a second pin coupling hole  579  that is pin-coupled with the second coupling pin  525  of the second coupling block  523 . 
     The second jig clamp  577  attaches the second coupling block  523  coupled to the second pin coupling hole  579  of the second coupling housing  575  through a second coupling pin  525  to a second coupling housing  575 . 
     The second jig clamp  577  is fixedly installed on the upper end of the second post frame  571 . The second jig clamp  577  is provided as a clamper of a known technology for clamping or unclamping the second coupling block  523  through a clamp cylinder. 
     Referring to  FIG.  8    to  FIG.  10   , in an exemplary embodiment of the present disclosure, the third moving member  610  is installed on the main-buck frame  51  separately from the second moving member  550  to reciprocate along the vehicle width direction. 
     For example, the third moving member  610  is provided in a plate shape, and is installed so as to reciprocate in the vehicle width direction by the fourth driving source  611  on the upper surface of the main-buck frame  51 . 
     Here, the fourth driving source  611  includes a third operating cylinder  613  fixedly installed to the main-buck frame  51  and has an operating rod that operates backward and forward by pneumatic pressure. The third actuating cylinder  613  is connected to the third moving member  610  through an actuating rod. 
     In an exemplary embodiment of the present disclosure, the mounting frame  640  is for mounting the quarter portion side gate  650 , which will be further described later, and is provided in a frame structure in which horizontal frames and vertical frames are interconnected, and is fixedly installed on the third moving member  610 . 
     In an exemplary embodiment of the present disclosure, the quarter portion side gate  650  regulates the quarter portion  4   e  of the side assembly  3  in the main-buck section  50  and is mounted on the mounting frame  640 . As shown in  FIG.  12   , the quarter portion side gate  650  includes a gate frame  651 , a fastening portion  653 , and a third clamper  655 . 
     The gate frame  651  is provided so as to be mountable to the arm tip of a handling robot (not shown in the drawing) through the robot coupling portion  652  and is fixedly installed on the mounting frame  640 . 
     The gate frame  651  is coupled to the docking coupling portion  631  provided in the mounting frame  640  through a lower end portion. The fastening portions  653  are provided on both sides of the gate frame  651 , respectively, and are mutually fastened with the mounting portions  630  provided in the mounting frame  640 . 
     Here, the lower end of the gate frame  651  is coupled to the docking coupling portion  631  through a coupling means having a protrusion and a groove. The fastening portion  653  is fitted into the mounting portion  630  and fastened to the mounting portion  630  through fastening means such as bolts. 
     Referring to  FIG.  3   , in an exemplary embodiment of the present disclosure, in the main-buck section  50 , the distance between the side assemblies  3  located on both sides of the floor assembly  2  is measured, and according to the measured value, the second post frame  571  and the mounting frame  640  may be moved to a set position. 
     To this end, the exemplary embodiment of the present disclosure includes the second sensor  710  installed in the main-buck section  50 . The second sensor  710  may include a known technology vision sensor. The second sensor  710  measures the distance between the side assemblies  3  positioned on both sides of the floor assembly  2  and outputs the measured value to a controller (not shown in the drawing). 
     Referring to  FIG.  8    to  FIG.  10    with  FIG.  3   , in an exemplary embodiment of the present disclosure, the second and third position correction units  730  and  750  correct the positions of the second and third moving members  550  and  610  with respect to the main-buck frame  51  in the vehicle width direction according to the measured value of the second sensor  710 . 
     In the above, the second position correction unit  730  is in stopping contact with the main-buck frame  51  and the second moving member  550 . In addition, the third position correction unit  750  is installed to the main-buck frame  51  and the third movable member  610  so as to be in stopping contact with each other. 
     The second and third position correction units  730  and  750  are, as shown in  FIG.  7    previously disclosed, the second and third fixed stoppers  731  and  751  and the second and third movable stoppers  741  and  761 , respectively. 
     The second and third fixing stoppers  731  and  751  are fixed to the second and third moving members  550  and  610 , respectively. Each of the second and third fixing stoppers  731  and  751  is provided in a plate shape. The second and third fixed stoppers  731  and  751  form third and fourth inclined surfaces  733  and  753  inclined toward one side with respect to the vehicle body conveying direction, respectively. 
     The second and third movable stoppers  741  and  761  are installed on the main-buck frame  51  so as to reciprocate forward and backward along the vehicle body transport direction in correspondence with the second and third fixed stoppers  731  and  751 , respectively. The second and third movable stoppers  741  and  761  have a plate shape and are provided to be in surface contact with the second and third fixed stoppers  731  and  751 , respectively. 
     The second and third movable stoppers  741  and  761  are inclined on the other side based on the vehicle body conveying direction, and the third and fourth inclined surfaces  733  and  753  of the second and third fixed stoppers  731  and  751  and the fifth and sixth inclined surfaces  743  and  763  capable of surface contact are formed, respectively. 
     In the above, the second and third movable stoppers  741  and  761  move back and forth along the vehicle body transport direction by the fifth and sixth driving sources  745  and  765 , respectively. The fifth and sixth driving sources  745  and  765  include second and third linear modules  747  and  767  installed on the main buck frame  51 , respectively. 
     The second and third linear modules  747  and  767  includes linear motors  751  and  771 , and movement blocks  755  and  775  linearly reciprocating along the vehicle body transport direction through the linear guides  753  and  773  by driving the linear motors  751  and  771 , respectively. Here, the second and third movable stoppers  741  and  761  are fixedly installed on the moving blocks  755  and  775 , respectively. 
     Meanwhile, referring again to  FIG.  1    and  FIG.  2   , the main-buck unit  500  according to the embodiment of the present disclosure as described above includes the second welding robots  12  and second and third storage units  820  and  830  as mentioned above. 
     The second welding robots  12  are installed in the main-buck section  50 , can weld the roof portion  4   d  and the cowl  7  of the side assembly  3 , the front roof rail  8   a , the rear roof rail  8   b , and the package tray  9 , and weld the quarter portion  4   e  of the side assembly  3  and the floor assembly  2 . 
     The second storage unit  820  is installed in the main-buck section  50  and may store different main-buck side jigs  510  for each vehicle type. The main-buck side jigs  510  stored in the second storage unit  820  may be withdrawn by the second handling robot  102 . 
     In addition, the third storage unit  830  is installed in the main-buck section  50  and may store side gates  650  of the quarter unit that are different for each vehicle type. The quarter portion side gates  650  stored in the third storage unit  830  may be withdrawn by a handling robot not shown in the drawing. 
     Hereinafter, the operation of the vehicle body assembly system  100  according to an exemplary embodiment of the present disclosure configured as described above and the assembly process of the vehicle body using the vehicle body assembly system  100  will be described in detail with reference to the previously disclosed drawings. 
     First, in an exemplary embodiment of the present disclosure, the floor assembly  2  assembled in the sub-assembly line is transferred to the pre-buck section  20  along the transfer path set through the carriage line  1 . 
     In this process, the first moving members  150  on both sides of the transport path in the pre-buck section  20  is in a state of being moved backward in a direction away from each other (a vehicle width direction) together with the first guide post  170  by the driving of the first driving source  151 . Further, in the pre-buck section  20 , the first handling robot  101  is equipped with a pre-buck side jig  110  of a vehicle type set at the tip of the arm thereof. 
     In this state, in an embodiment of the present disclosure, in a state in which the side assembly  3  is aligned through a separate alignment jig, the pre-buck side jig  110  is moved to the side assembly  3  through the first handling robot  101 . Then, in an exemplary embodiment of the present disclosure, the seal side  4   a  and the front and rear sides  4   b  and  4   c  of the side assembly  3  are regulated through the pre-buck side jig  110 . 
     Here, the pre-buck side jig  110  clamps the seal side  4   a  and the front and rear sides  4   b  and  4   c  of the side assembly  3  different for each vehicle type through the first clampers  113 . 
     In the above process, in an exemplary embodiment of the present disclosure, the width of the floor assembly  2  along the vehicle width direction is measured through the first sensor  210 , and the measured value is output to a controller (not shown). 
     Then, the controller compares the measured value of the first sensor  210  with a preset reference value, calculates a position correction value according to the difference between the measured value and the reference value, and applies a control signal according to the position correction value to the second driving source  245  of the first position correction unit  230 . 
     Accordingly, the first linear module  247  of the second driving source  245  linearly reciprocates the moving block  255  along the vehicle body transport direction through the linear guide  253  by driving the linear motor  251 , and moves the first movable stopper  241  forward or backward along the vehicle body transport direction to a position corresponding to the position correction value. 
     Then, in an exemplary embodiment of the present disclosure, the first moving member  150  is moved forward by the forward operation of the first operating cylinder  153  of the first driving source  151 . Here, the first moving member  150  advances until the first gradient surface  233  of the first fixed stopper  231  stops contacting the second gradient surface  243  of the first movable stopper  241 . Accordingly, in an exemplary embodiment of the present disclosure, the first guide post  170  may be positioned at a set position by the first moving member  150 . 
     Next, in an exemplary embodiment of the present disclosure, the pre-buck side jig  110  clamping the seal side  4   a  of the side assembly  3  and the front and rear sides  4   b  and  4   c  is moved toward the first guide post  170  through the first handling robot  101 . 
     After this, in an exemplary embodiment of the present disclosure, the first post coupling portion  121  of the pre-buck side jig  110  is coupled to the first jig coupling portion  173  of the first guide post  170  by the first handling robot  101 . 
     Here, the first coupling block  123  of the first post coupling portion  121  is coupled to the first coupling housing  175  of the first jig coupling portion  173  through a first guide roller  127 . In an exemplary embodiment of the present disclosure, the first coupling pin  125  of the first coupling block  123  is coupled to the first pin coupling hole  179  of the first coupling housing  175 , and the first coupling block  123  is coupled to the first coupling housing  175 . 
     In such a state, in an exemplary embodiment of the present disclosure, the first coupling block  123  is clamped by the clamping operation of the first jig clamp  177  of the first jig coupling portion  173 , and the first post coupling portion  121  of the pre-buck side jig  110  is fixed to the first jig coupling portion  173 . 
     Therefore, in an exemplary embodiment of the present disclosure, in the pre-buck section  20 , the lower seal side  4   a  of the side assembly  3  and the front and rear sides  4   b  and  4   c  are regulated through the pre-buck side jig  110 , and the side assembly  3  can be accurately matched to the set positions on both sides of the floor assembly  2 . Furthermore, in an exemplary embodiment of the present disclosure, the distribution of the position (assembly) of the side assembly  3  may be minimized through the first position correction unit  230  described above. 
     Next, in an exemplary embodiment of the present disclosure, the lower seal side  4   a  and the front and rear sides  4   b  and  4   c  of the side assembly  3  are welded to both sides of the floor assembly  2  through the first welding robot  11 . 
     When welding as above is completed, in an exemplary embodiment of the present disclosure, in the pre-buck section  20 , the body assembled with side assemblies  3  on both sides of the floor assembly  2  is transferred to the main-buck section  50  along the transfer path of the carriage line  1 . 
     In this process, in the main-buck section  50 , the second moving members  550  on both sides of the transport path are in a state of being moved backwards along with the second guide post  570  in a direction away from each other (the vehicle width direction) by driving of the third driving source  551 . 
     In addition, the third moving members  610  on both sides of the transfer path are in a state of being moved backward in a direction away from each other (the vehicle width direction) together with the mounting frame  640  by driving of the fourth driving source  611 . 
     Here, the second handling robot  102  is equipped with a main-buck side jig  510  of a vehicle type set at the tip of the arm. In addition, a quarter portion side gate  650  of a set vehicle type is mounted on the mounting frame  640  on the third moving member  610 . 
     Also, in the above process, the cowl  7 , the front roof rail  8   a , the rear roof rail  8   b , and the package tray  9  as a CRP part regulated by the CRP carriage  10  are moved to the roof portion  4   d  of the side assembly  3 . 
     In this state, in an exemplary embodiment of the present disclosure, the distance between the side assemblies  3  located on both sides of the floor assembly  2  is measured through the second sensor  710 , and the measured value is output to a controller (not shown in the drawing). 
     Then, the controller compares the measured value of the second sensor  710  with a preset reference value, calculates a position correction value according to the difference between the measured value and the reference value, and applies a control signal according to the position correction value to the fifth driving source  745  of the second position correction unit  730  and the sixth driving source  765  of the third position correction unit  750 . 
     Accordingly, the second linear module  747  of the fifth driving source  745  linearly reciprocates the moving block  755  through the linear guide  753  by driving the linear motor  751  along the vehicle body transport direction, and moves the second movable stopper  741  forward or backward along the vehicle body transport direction to a position corresponding to the position correction value. 
     At the same time, the third linear module  767  of the sixth driving source  765  linearly reciprocates the moving block  775  along the vehicle body transport direction through the linear guide  773  by driving the linear motor  771 , and moves the third movable stopper  761  forward or backward along the vehicle body transport direction to a position corresponding to the position correction value. 
     Then, in an exemplary embodiment of the present disclosure, the second moving member  550  is moved forward by the forward operation of the second operating cylinder  553  of the third driving source  551 . Here, the second moving member  550  moves forward until the third inclined surface  733  of the second fixed stopper  731  makes stop contact with the fourth inclined surface  753  of the second movable stopper  741 . Accordingly, in an exemplary embodiment of the present disclosure, the second guide post  570  may be positioned at a set position by the second moving member  550 . 
     At the same time, in an exemplary embodiment of the present disclosure, the third moving member  610  is moved forward by the forward operation of the third operating cylinder  613  of the fourth driving source  611 . Here, the third moving member  610  moves forward until the fifth inclined surface  743  of the third fixed stopper  751  makes stop contact with the sixth inclined surface  763  of the third movable stopper  761 . Accordingly, in an exemplary embodiment of the present disclosure, the quarter portion side gate  650  together with the mounting frame  640  may be positioned at a set position by the third moving member  610 . 
     Next, in an exemplary embodiment of the present disclosure, the main-buck side jig  510  is moved toward the second guide post  570  through the second handling robot  102 . After this, in an exemplary embodiment of the present disclosure, the second post coupling portion  521  of the main-buck side jig  510  is coupled to the second jig coupling portion  573  of the second guide post  570  by the second handling robot  102 . 
     Here, the second coupling block  523  of the second post coupling portion  521  is coupled to the second coupling housing  575  of the second jig coupling portion  573  through the second guide roller  527 . In an exemplary embodiment of the present disclosure, the second coupling pin  525  of the second coupling block  523  is coupled to the second pin coupling hole  579  of the second coupling housing  575 , and the second coupling block  523  is a second coupling housing  575 . 
     In such a state, in an exemplary embodiment of the present disclosure, the second coupling block  523  is clamped by the clamping operation of the second jig clamp  577  of the second jig coupling portion  573 , and the second post coupling portion  521  of the main-buck side jig  510  is fixed to the second jig coupling portion  573 . 
     In this process, in an exemplary embodiment of the present disclosure, the first coupling rod  531  of the main-buck side jig  510  on one side of the transport path and the second coupling rod  532  of the main-buck side jig  510  on the other side of the transport path are mutually coupled, and the absolute width (width in the vehicle width direction) between both side assemblies  3  can be maintained. 
     Then, in an exemplary embodiment of the present disclosure, both side roof portions  4   d  of the side assembly  3  are regulated through the second clampers  513  of the main-buck side jig  510 , and the quarter portion  4   e  of the side assembly  3  is regulated through the third clampers  655  of the quarter portion side gate  650 . 
     Therefore, in an exemplary embodiment of the present disclosure, the cowl  7 , the front roof rail  8   a , the rear roof rail  8   b , and the package tray  9  as the CRP components regulated in the CRP carriage  10  can be exactly matched to the roof portion  4   d  of the side assembly  3 . Furthermore, in an exemplary embodiment of the present disclosure, the distribution of the position (assembly) of the side assembly  3  may be minimized through the second and third position correction units  730  and  750 . 
     Next, in an exemplary embodiment of the present disclosure, through the second welding robot  12 , the roof portion  4   d  and the cowl  7  of the side assembly  3 , the front roof rail  8   a , the rear roof rail  8   b , and the package tray  9  are welded, and the quarter portion  4   e  of the side assembly  3  and the floor assembly  2  are welded. 
     According to the vehicle body assembly system  100  according to an exemplary embodiment of the present disclosure as described so far, unlike the conventional technology that forms the skeleton of the vehicle body in a single process, by separating the vehicle body assembly process into two processes, it is possible to assemble the vehicle body of multiple vehicle types, and it is possible to commonize multiple vehicle models using a robot. 
     Therefore, in an exemplary embodiment of the present disclosure, flexible production of multiple vehicle types is possible, equipment preparation time can be reduced, weight reduction and simplification of the entire equipment can be achieved, and investment costs in the initial stage and when adding vehicle types can be reduced. 
     Furthermore, in an exemplary embodiment of the present disclosure, by minimizing the position distribution of the side assembly  3  through the first, second, and third position correction units  230 ,  730 ,  750 , deterioration of the quality of the vehicle body assembly due to the distribution of the position of the side assembly  3  can be prevented. 
     Furthermore, in an exemplary embodiment of the present disclosure, the first, second, and third moving members  150 ,  550  and  610  are moved by a simple configuration such as an operating cylinder without using a servo motor, and the side assembly  3  can be assembled on both sides of the floor assembly  2 . Therefore, it is possible to reduce the weight of the facility and reduce the initial investment cost. 
     While this disclosure has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the disclosure is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.