Abstract:
A rivet module is disclosed. The rivet module is provided to join at least two sheets of base materials in a solid state, the rivet module including: i) a shank portion to be mounted on a reciprocal and rotatable joining tool; ii) a base material friction portion that is integrally connected to the shank portion and drills through the base material friction portion as the joining tool causes the base material friction portion to be rotated while applying pressure to the base materials; and iii) a base material fastening portion that is fixedly fitted to the shank portion, supports the base material friction portion, and is fastened to the base materials through a thread formed on the outer peripheral surface thereof.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to and the benefit of Korean Patent Application No. 10-2014-0124566 filed in the Korean Intellectual Property Office on Sep. 18, 2014, the entire contents of which are incorporated herein by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    (a) Field of the Invention 
         [0003]    An exemplary embodiment of the present invention relates to a fastener element, and more particularly, to a rivet module for mechanically joining two or more sheets of base materials and a joining structure and method using the same. 
         [0004]    (b) Description of the Related Art 
         [0005]    In general, methods of forming a variety of structures by joining a plurality of base materials, for example, metal or non-metal plates, sheets, and randomly-shaped objects involve mechanically joining overlapping base materials by fastener elements such as bolts, nuts, rivets, etc. 
         [0006]    Among them, the mechanical joining method using a rivet allows the fastening of base materials by making a hole in target base materials, inserting a rivet in the hole, and plastically deforming the rivet. 
         [0007]    However, this joining method using a rivet requires an additional process of drilling a hole in the base materials, which may degrade productivity and workability. 
         [0008]    To address this problem, those in the art have drifted toward the simple method of joining a plurality of base materials by a fastener element called an FDS (Flow Drill Screw). This fastener element is also referred to as a friction stir rivet. 
         [0009]    In one example, an FDS rivet-type fastener element includes a head portion mounted on a pressure/rotation device, a screw portion integral with the head portion and having a thread on the outer peripheral surface, and a drilling portion integrally connected to the screw portion and for drilling through a base material. 
         [0010]    Accordingly, in the joining method using the above-described fastener element, when the head portion is mounted on a pressure/rotation device and rotated under pressure by the pressure/rotation device, with the drilling portion being in contact with overlapping base materials, a hole is formed in the base materials by the friction between the drilling portion and the base materials and the base materials are fastened with the screw portion. Thus, the base materials are joined together. 
         [0011]    Even with a joining structure obtained by joining base materials with such a fastener element, however, the quality of external appearance of joined products may be low because the screw portion and the drilling portion stick out from the base materials, and the joint strength of the base materials may be low because the base materials are joined in a solid state simply with the screw portion. 
         [0012]    The above information disclosed in this section is only for enhancement of understanding of the background of the invention 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 OF THE INVENTION 
       [0013]    The present invention has been made in an effort to provide a rivet module which increases joint strength of base materials and improves quality of external appearance of joined products by screwing the base materials together through a hole drilled in them and at the same time using a blind rivet, and a joining structure and method using the same. 
         [0014]    An exemplary embodiment of the present invention provides a rivet module for joining at least two sheets of base materials in a solid state, the rivet module including: i) a shank portion to be mounted on a reciprocal and rotatable joining tool; ii) a base material friction portion that is integrally connected to the shank portion and drills through the base material friction portion as the joining tool causes the base material friction portion to be rotated while applying pressure to the base materials; and iii) a base material fastening portion that is fixedly fitted to the shank portion, supports the base material friction portion, and is fastened to the base materials through a thread formed on the outer peripheral surface thereof. 
         [0015]    In the rivet module according to the exemplary embodiment of the present invention, the shank portion may be broken off from the base material friction portion. 
         [0016]    In the rivet module according to the exemplary embodiment of the present invention, the shank portion may have a non-circular cross-section and couple with the base material fastening portion through mating connection. 
         [0017]    In the rivet module according to the exemplary embodiment of the present invention, the shank portion may have a polygonal cross-section and be rounded on the edges. 
         [0018]    In the rivet module according to the exemplary embodiment of the present invention, the part of the base material friction portion connected to the shank portion may have a larger cross-sectional area than the shank portion, and the base material friction portion may be integrally connected to the shank portion. 
         [0019]    In the rivet module according to the exemplary embodiment of the present invention, the circular cross-sectional diameter of the base material friction portion may becomes gradually larger and then smaller from the part connected to the shank portion toward the tip, and the tip may be sharpened. 
         [0020]    In the rivet module according to the exemplary embodiment of the present invention, the base material fastening portion may have a hollow space into which the shank portion and the base material friction portion are fitted. 
         [0021]    In the rivet module according to the exemplary embodiment of the present invention, the hollow space may include: a first portion having a shape corresponding to the cross-section of the shank portion; and a second portion connected to the first portion and having a shape corresponding to the region where the cross-sectional diameter of the base material friction portion becomes gradually larger. 
         [0022]    In the rivet module according to the exemplary embodiment of the present invention, the shank portion may be fitted to the first portion through the second portion of the base material fastening portion. 
         [0023]    In the rivet module according to the exemplary embodiment of the present invention, the base material friction portion may be fitted to the second portion. 
         [0024]    In the rivet module according to the exemplary embodiment of the present invention, a flange-shaped head supporting the joining tool may be formed on one end of the base material fastening portion. 
         [0025]    In the rivet module according to the exemplary embodiment of the present invention, a drilling guide that penetrates into the base materials may be formed on the other end of the base material fastening portion which corresponds to the second portion. 
         [0026]    In the rivet module according to the exemplary embodiment of the present invention, the drilling guide may be formed in a tapered shape, by which the cross-sectional diameter becomes gradually smaller. 
         [0027]    In the rivet module according to the exemplary embodiment of the present invention, the thread may be formed between the head and the drilling guide on the outer peripheral surface of the base material fastening portion. 
         [0028]    In the rivet module according to the exemplary embodiment of the present invention, the base material friction portion may be pulled upward by the joining tool and enter the first portion. 
         [0029]    In the rivet module according to the exemplary embodiment of the present invention, the base material fastening portion may be plastically deformed by the base material friction portion, causing the cross-section to expand outward. 
         [0030]    Another exemplary embodiment of the present invention provides a joining structure using the rivet module, which includes a shank portion, a base material friction portion, and a base material fastening portion and joins at least two sheets of base materials in a solid state, wherein the base material fastening portion with a hollow space is screwed to the base materials by a thread formed on the outer peripheral surface, penetrating the base materials, and the base material friction portion is arranged within the hollow space of the base material fastening portion, while the base material fastening portion is plastically deformed by the base material friction portion, causing the cross-section to expand outward. 
         [0031]    In the joining structure using the rivet module according to the exemplary embodiment of the present invention, the base material fastening portion may include: a flange-shaped head formed on one end and supporting one side of the base materials; and a drilling guide formed on the other end and protruding to the other side of the base materials while penetrating the base materials. 
         [0032]    In the joining structure using the rivet module according to the exemplary embodiment of the present invention, the circular cross-sectional diameter of the base material friction portion may become gradually larger and then smaller from the head of the base material fastening portion toward the drilling guide, and the tip of the base material friction portion may be sharpened. 
         [0033]    In the joining structure using the rivet module according to the exemplary embodiment of the present invention, the base material friction portion may be exposed to the head through the hollow space of the base material fastening portion, and a breaking mark of the shank portion may be formed in the exposed region. 
         [0034]    Yet another exemplary embodiment of the present invention provides a joining method using the rivet module including a shank portion, a base material friction portion, and a base material fastening portion, the method including: fixedly mounting the shank portion on a joining tool; moving the rivet module to two or more sheets of overlapping base materials and drilling through the base materials by the base material friction portion by applying pressure on and rotating the rivet module while supporting the base material fastening portion through the joining tool; screwing the base material fastening portion to the base materials through the hole drilled by the base material fastening portion; causing the base material friction portion to enter the base material fastening portion by pulling the shank portion through the joining tool, and causing the cross-section of the base material fastening portion to expand outward by means of the base material friction portion; and breaking off the shank portion from the base material friction portion. 
         [0035]    In the joining method using the rivet module according to the exemplary embodiment of the present invention, a hole may be drilled in the base materials by the friction of the base material friction portion, the base material fastening portion may be screwed to the base materials, and the cross-section of the base material fastening portion may expand using a blind rivet. 
         [0036]    In the joining method using the rivet module according to the exemplary embodiment of the present invention, the rivet may be rotated under pressure through the joining tool, and the base material fastening portion may be inserted into the hole. 
         [0037]    In the joining method using the rivet module according to the exemplary embodiment of the present invention, the base material fastening portion and the base materials may be screwed together through a thread formed on the outer peripheral surface of the base material fastening portion. 
         [0038]    According to an embodiment of the present invention, two or more sheets of base materials are joined together by drilling through the base materials by the friction of the base material friction portion on the base materials, screwing the base material fastening portion to the base materials, and causing the cross-section of the base material fastening portion to expand using a blind rivet by means of the base material friction portion. 
         [0039]    Accordingly, in the embodiment of the present invention, the joint strength of the base materials can be further increased because two or more sheets of base materials are joined by screwing the base materials through a hole drilled in them by friction and plastically deforming the fastener elements of the base materials using a blind rivet. 
         [0040]    Furthermore, in the embodiment of the present invention, only the drilling guide of the base material fastening portion penetrates the base materials and protrudes toward the lowermost surfaces of the base materials. This further improves the quality of external appearance of joined products, unlike the prior art methods in which the screw portion and the drilling portion stick out from the base materials. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0041]    The drawings are provided for reference to explain an illustrative embodiment of the present invention, and the technical spirit of the present disclosure should not be interpreted to be limited to the accompanying drawings. 
           [0042]      FIG. 1  is an exploded perspective view showing a rivet module according to an exemplary embodiment of the present invention. 
           [0043]      FIG. 2  is an assembled perspective view showing the rivet module according to the exemplary embodiment of the present invention. 
           [0044]      FIG. 3  is a cross-sectional view showing the rivet module according to the exemplary embodiment of the present invention. 
           [0045]      FIGS. 4 to 7  are views showing a joining method using a rivet module according to an exemplary embodiment of the present invention. 
           [0046]      FIG. 8  is a view showing a joining structure using a rivet module according to an exemplary embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0047]    The present invention will be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention 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 invention. 
         [0048]    To clearly describe the present disclosure, parts that are irrelevant to the description are omitted. Like numerals refer to like or similar constituent elements throughout the specification. 
         [0049]    The size and the thickness of each component illustrated in the drawings are arbitrarily illustrated for better understanding and ease of description, but the present disclosure is not limited to the illustration. In the drawings, the thicknesses of various portions and regions are enlarged for clarity. 
         [0050]    Further, in the following detailed description, names of constituents, which are in the same relationship, are divided into “the first”, “the second”, and the like, but the present disclosure is not limited to the order in the following description. 
         [0051]    In the 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. 
         [0052]    In addition, the terms such as “ . . . unit”, “ . . . means”, “ . . . part”, etc., which are disclosed in the specification, refer to a unit of an inclusive constituent which performs at least one function or operation. 
         [0053]      FIG. 1  is an exploded perspective view showing a rivet module according to an exemplary embodiment of the present invention,  FIG. 2  is an assembled perspective view of  FIG. 1 , and  FIG. 3  is a cross-sectional view of  FIG. 2 . 
         [0054]    Referring to  FIGS. 1 to 3 , the rivet module  100  according to the exemplary embodiment of the present invention may apply to a vehicle body assembly process in which two or more sheets of overlapping base materials  1  (hereinafter, refer to  FIG. 4 ), for example, vehicle body panels, are joined together. 
         [0055]    However, the base materials  1  are not necessarily limited to vehicle body panels, but may include a variety of vehicle body structures such as vehicle body members, frames, etc. 
         [0056]    Furthermore, the scope of protection of this invention should not be construed as limited to assembly of vehicle bodies, and the technical spirit of this invention can apply to any structures of various types and purposes as long as they are made by assembling components. 
         [0057]    The base materials  1  may include metal sheet materials such as aluminum sheets or steel sheets (including high-tensile steel sheets), and nonmetal materials such as composites, plastics, or rubber. Moreover, the base materials  1  may include plates made of the same material or plates made of different materials. 
         [0058]    The rivet module  100  according to the exemplary embodiment of the present invention is for joining two or more sheets of overlapping base materials  1  in a solid state by a mechanical joining method such as friction stir processing or plastic deformation. 
         [0059]    The following components will now be described when the rivet module  100  is viewed in a vertical direction while being erected. A part facing upward is defined as a top part or an upper part, and a part facing downward is defined as a bottom part or a lower part. 
         [0060]    However, the terms may be defined by relatively meanings. The rivet module  100  may be viewed in a different direction depending on the reference position of the rivet module and the direction in which the base materials  1  are joined. Therefore, the reference direction of this exemplary embodiment is not necessarily limited to the above direction. 
         [0061]    In the exemplary embodiment of the present invention, the rivet module  100  includes a joining tool  200  (hereinafter, refer to  FIG. 4 ) for mechanically joining the base materials  1  in solid state using the rivet module  100 . 
         [0062]    The joining tool  200  can clamp the rivet module  100  according to the exemplary embodiment of the present invention, and can vertically move and rotate the rivet module  100 . 
         [0063]    The rivet module  100  according to the exemplary embodiment of the present invention to be described hereinafter has a structure that increases the joint strength of the base materials  1  and improves the quality of external appearance of joined products by screwing the base materials  1  through a hole drilled in them by friction, and at the same time plastically deforming the fastener elements of the base materials  1  using a blind rivet. 
         [0064]    To this end, the rivet module  100  according to the exemplary embodiment of the present invention basically includes a shank portion  10 , a base material friction portion  30 , and a base material fastening portion  50 . 
         [0065]    In the exemplary embodiment of the present invention, the shank portion  10 , which is a rod of a given length, is fixedly mounted on the aforementioned joining tool  200 . 
         [0066]    The shank portion  10  may have a non-circular cross-section, and is coupled with the base material fastening portion  50 , which is to be described in further detail, through mating connection. For example, the shank portion  10  may have a polygonal (e.g., rectangular) cross-section and may be rounded at the edges. 
         [0067]    The shank portion  10  has a non-circular, polygonal cross-section so that the base material fastening portion  50  to be described later in further detail is fixed to the shank portion  10  and the shank portion  10  rotates together with the base material fastening portion  50  by the joining tool  200 . 
         [0068]    In the exemplary embodiment of the present invention, the base material friction portion  30  is for drilling through the base materials  1  by friction caused by pressure and torque applied from the joining tool  200  through the shank portion  10 . That is, the base material friction portion  30  is able to drill through the base materials  1  as the joining tool  200  causes the base material friction portion  30  to be rotated while applying pressure to the base materials  1 . 
         [0069]    Referring to the drawings, the base material friction portion  30  is integrally connected to the bottom part of the shank portion  10 . The part of the base material friction portion  30  connected to the bottom part of the shank portion  10  may have a larger cross-sectional area than the shank portion  10 , and the base material friction portion  30  may be integrally connected to the shank portion  10 . 
         [0070]    For example, the base material friction portion  30  may be configured in such a manner that its circular cross-sectional diameter becomes gradually larger and then smaller from the part (the top in the figures) connected to the shank portion  10  toward the tip (the bottom in the figures), and the tip is sharpened. 
         [0071]    That is, the base material friction portion  30  has a bullet shape, and forms a convex surface between the part connected to the shank portion  10  and the sharpened tip. 
         [0072]    Since the part of the base material friction portion  30  connected to the bottom part of the shank portion  10  has a larger cross-sectional area than the shank portion  10 , the shank portion  10  may be broken off from the base material friction portion  30  by external force. 
         [0073]    In the exemplary embodiment of the present invention, the base material fastening portion  50  is for substantially joining the base materials  1  through the hole drilled in the base materials  1  by the base material friction portion  30 . The base material fastening portion  50  has a structure that is fixedly fitted to the shank portion  10 , supported on the base material friction portion  30 , and screwed to the base materials  1  through the hole in the base materials  1 . 
         [0074]    Specifically, the base material fastening portion  50  has a hollow space  51  into which the shank portion  10  and the base material friction portion  30  are partially fitted. A thread  53  to be screwed to the base materials  1  through the hole in the base materials  1  is formed on the outer peripheral surface of the base material fastening portion  50 . 
         [0075]    A flange-shaped head  55  supporting the joining tool  200  and the uppermost surfaces of the base materials  1  is formed on one end (the top part in the figures) of the base material fastening portion  50 . 
         [0076]    The hollow space  51  of the base material fastening portion  50  includes a first portion  52   a  having a shape corresponding to the cross-section of the shank portion  10  and a second portion  52   b  connected to the first portion  52   a  and having a shape corresponding to the region where the cross-sectional diameter of the base material friction portion  30  becomes gradually larger. 
         [0077]    In this case, the first portion  52   a  is the part where the shank portion  10  is fitted through the second portion  52   b , and the second portion  52   b  is the part where one part (which gradually increases in cross-sectional diameter) of the base material friction portion  30  is fitted. 
         [0078]    That is, the shank portion  10  may be fitted to the first portion  52   a  through the second portion  52   b  from the underside of the base material fastening portion  50 , and one part of the base material friction portion  30  may be fitted to the second portion  52   b.    
         [0079]    A drilling guide  57  is formed on the other end (the bottom part in the figures) of the base material fastening portion  50  to penetrate into the base materials  1  through the hole drilled in the base materials  1  by means of the base material friction portion  30 . 
         [0080]    The drilling guide  57  may be formed in a tapered shape, by which the cross-section diameter becomes gradually smaller from the top to the bottom, corresponding to the second portion  52   b.    
         [0081]    The drilling guide  57  is formed in the base material fastening portion  50  in order to allow the base material fastening portion  50  to easily penetrate through the hole drilled in the base materials  1 . 
         [0082]    In this case, the aforementioned thread  53  may be formed between the head  55  and the drilling guide  57  on the outer peripheral surface of the base material fastening portion  50 . 
         [0083]    On the other hand, in the exemplary embodiment of the present invention, the base material friction portion  30  may be pulled upward by the joining tool  200  and enter the first portion  52   a  from the second portion  52   b  of the base material fastening portion  50 . 
         [0084]    Accordingly, the base material fastening portion  50  may be plastically deformed by the base material friction portion  30  and expand outward from the hollow space  51  because the cross-sectional area of the shank portion  10  fitted to the first portion  52   a  is smaller than the cross-sectional area of the base material friction portion  30 . 
         [0085]    Now, a method of joining materials using the thus-configured rivet module  100  according to the exemplary embodiment of the present invention will be described in detail with reference to the previously disclosed drawings and the accompanying drawings. 
         [0086]      FIGS. 4 to 7  are views showing a joining method using a rivet module according to an exemplary embodiment of the present invention. 
         [0087]    Referring to  FIGS. 4 to 7 , in the exemplary embodiment of the present invention, the base materials  1  can be joined using the aforementioned joining tool  200  in such a manner that the base materials  1  are screwed together through a hole drilled in them by the rivet module  100 , and at the same time the fastener elements of the base materials  1  are plastically deformed using a blind rivet. 
         [0088]    The joining tool  200  includes a mount portion  101  for clamping the shank portion  10  of the rivet module  100  and a drive portion  103  for rotating the mount portion  101  while vertically reciprocating the mount portion  101 . 
         [0089]    The joining tool  200  of this type is configured as a component of a friction stir system as is well known to those skilled in the art, so further detailed description of this component will be omitted in this specification. 
         [0090]    An example of joining the base materials  1  using the joining tool  200  will now be described. First of all, according to the exemplary embodiment of the present invention, the shank portion  10  of the rivet module  100  is mounted on the mount portion  101  of the joining tool  200 , as shown in  FIG. 4 . 
         [0091]    Hereupon, the base material fastening portion  50  is fixedly fitted to the shank portion  10  and supported on the base material friction portion  30 , and the head  55  of the base material fastening portion  50  is supported on the mount portion  101 . 
         [0092]    That is, the shank portion  10  is fitted to the first portion  52   a  through the second portion  52   b  of the base material fastening portion  50  on the underside of the base material fastening portion  50 , and one part of the base material fastening portion  30  is fitted to the second portion  52   b.    
         [0093]    With this configuration, in the exemplary embodiment of the present invention, as shown in  FIG. 5 , the rivet module  100  is moved to two or more sheets of overlapping base materials  1  through the drive portion  103  of the joining tool  200 , the base material friction portion  30  of the rivet module  100  applies pressure on the base materials  1 , and the drive portion  103  of the joining tool  200  rotates the rivet module  100 . 
         [0094]    Then, the base material friction portion  30  drills through the base materials  1  by the friction caused by the pressure and torque applied from the drive portion  103  of the joining tool  200  through the shank portion  10 . 
         [0095]    With the hole is drilled in the base materials  1  through the base material friction portion  30 , the rivet module  100  is continuously rotated under pressure according to the exemplary embodiment of the present invention. 
         [0096]    Hereupon, the base material fastening portion  50  of the rivet module  100  is applying pressure to the base materials  1  while rotating together with the shank portion by the pressure and torque applied from the drive portion  103  of the joining tool  200  through the shank portion  10 . 
         [0097]    Accordingly, the drilling guide  57  of the base material fastening portion  50  penetrates into the base materials  1  through the hole drilled in the base materials  1  by the base material friction portion  30 , and protrudes toward the lowermost surfaces of the base materials  1 . 
         [0098]    The base material fastening portion  50  is screwed to the base materials  1  by the thread  53  formed on the outer peripheral surface, and the head  55  of the base material fastening portion  50  supports the uppermost surfaces of the base materials  1 . 
         [0099]    With the base materials  1  being fastened by the base material fastening portion  50  as described above, according to the exemplary embodiment of the present invention, the shank portion  10  is pulled by the drive portion  103  of the joining tool  200 , as shown in  FIG. 6 . 
         [0100]    Then, the shank portion  10  is drawn out of the first portion  52   a  of the base material fastening portion  50 , and the base material friction portion  30  enters the first portion  52   a  while causing the second portion  52   b  of the base material fastening portion  50  to plastically deform the first portion  52   a.    
         [0101]    Accordingly, the base material fastening portion  50  may be plastically deformed by the base material friction portion  30  and expand outward from the hollow space  51  because the cross-sectional area of the shank portion  10  fitted to the first portion  52   a  is smaller than the cross-sectional area of the base material friction portion  30 . 
         [0102]    Therefore, in the exemplary embodiment of the present invention, as the cross-section of the base material fastening portion  50  expands outward from the hollow space  51  through the base material friction portion  30 , the joint strength of the base materials  1  can be further increased because of the expanded cross-section of the base material fastening portion  50 . 
         [0103]    Afterwards, in the exemplary embodiment of the present invention, the mount portion  101  of the joining tool  200  is removed from the shank portion  10 , and as shown in  FIG. 7 , the shank portion  10 , drawn out of the first portion  52   a  of the base material fastening portion  50 , is hit by a predetermined striking mechanism to break off the shank portion  10  from the base material friction portion  30 . 
         [0104]    Accordingly, in the exemplary embodiment of the present invention, the assembling of a joining structure  300 , obtained by joining the base materials  1  together using the rivet module  100  through a series of processes as described above, is completed (see  FIG. 8 ). 
         [0105]      FIG. 8  is a view showing a joining structure using a rivet module according to an exemplary embodiment of the present invention. 
         [0106]    Referring to  FIG. 8 , the joining structure  300  using the rivet module  100  according to the exemplary embodiment of the present invention is basically configured in such a manner that the base material fastening portion  50  with the hollow space  51  is screwed to two or more sheets of overlapping base materials  1  by the thread  53  formed on the outer peripheral surface, penetrating the base materials  1 . 
         [0107]    Moreover, the joining structure  300  according to the exemplary embodiment of the present invention is configured in such a manner that the base material friction portion  30  is arranged within the hollow space  51  of the base material fastening portion  50  and the cross-section of the base material fastening portion  50  expands outward from the hollow space  51  by plastic deformation caused by the base material friction portion  30 . 
         [0108]    The head  55  of the base material fastening portion  50  supports the uppermost surfaces of the base materials  1 . The drilling guide  57  of the base material fastening portion  50  penetrates the base materials  1  and protrudes toward the lowermost surfaces of the base materials  1 . 
         [0109]    In the exemplary embodiment of the present invention, the circular cross-sectional diameter of the base material friction portion  30  becomes gradually larger and then smaller from the head  55  of the base material fastening portion  50  toward the drilling guide  57 , and the tip of the base material friction portion  30  is sharpened. 
         [0110]    In this case, the base material friction portion  30  is exposed to the head  55  through the hollow space  51  of the base material fastening portion  50 , and a breaking mark  201  of the shank portion  10  is formed in the exposed region. 
         [0111]    According to the rivet module  100  and the joining structure  300  and method using the same according to the exemplary embodiment of the present invention as explained hitherto, two or more sheets of base materials  1  can be joined together by drilling through the base materials  1  by the friction of the base material friction portion  30  on the base materials  1 , screwing the base material fastening portion  50  to the base materials  1 , and causing the cross-section of the base material fastening portion  50  to expand using a blind rivet by means of the base material friction portion  30 . 
         [0112]    Therefore, in the exemplary embodiment of the present invention, two or more sheets of base materials  1  are joined by screwing the base materials  1  through a hole drilled in them by friction and plastically deforming the fastener elements of the base materials  1  using a blind rivet, thereby further increasing the joint strength of the base materials  1 . 
         [0113]    Furthermore, in the exemplary embodiment of the present invention, only the drilling guide  57  of the base material fastening portion  50  penetrates the base materials  1  and protrudes toward the lowermost surfaces of the base materials  1 . This further improves the quality of external appearance of joined products, unlike the prior art methods in which the screw portion and the drilling portion stick out from the base materials. 
         [0114]    Although the exemplary embodiments of the present invention have been described above, the present invention is not limited to those embodiments. It may be modified in various forms without departing from the scope of the claims, the detailed description, and the accompanying drawings of the present invention. Therefore, it is natural that such modifications are within the scope of the present invention. 
         [0000]    
       
         
               
             
               
               
             
           
               
                   
               
               
                 &lt;Description of symbols&gt; 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 1 base material 10 shank portion 
               
               
                   
                 30 base material friction portion 50 base material fastening portion 
               
               
                   
                 51 hollow space 52a first portion 
               
               
                   
                 52b second portion 53 thread 
               
               
                   
                 55 head 57 drilling guide 
               
               
                   
                 100 rivet module 101 mount portion 
               
               
                   
                 103 drive portion 200 joining tool 
               
               
                   
                 201 breaking mark 300 joining structure 
               
               
                   
                   
               
             
          
         
       
     
         [0115]    While this invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention 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.