Patent Publication Number: US-2009220321-A1

Title: Fastening metal fitting

Description:
TECHNICAL FIELD 
     The present invention relates to a fastening metal fitting such as a bolt, a plug and a socket screw. 
     BACKGROUND ART 
     Conventionally, it is a common practice to use, for example, as a fastening bolt for automobiles, a hexagonal socket head bolt formed of a head and an axial portion having a screw portion on its circumference, with a hexagonal socket formed at the center of the head. The hexagonal socket head bolt is fastened by a predetermined fastening axial force generated by the insertion of a hexagon wrench widely used in common into a hexagonal socket. 
     Also known as a fastening bolt for increasing a fastening force is a hexalobular socket head bolt whose cylindrical head has a hexalobular socket formed at its center with a circular curve continuing. The hexalobular socket head bolt is fastened by a predetermined fastening axial force generated by the insertion, into the above hexalobular socket, of a hexalobular wrench whose shape is the same as that of the above hexalobular socket and whose shape is special to fit the socket. 
     SUMMARY OF THE INVENTION 
     While the latter hexalobular socket head bolt has an advantage that torque is completely transmitted to securely fasten a target object, it has a problem that without a hexalobular wrench having a special shape at hand, the target object can be neither disassembled nor repaired to leave nothing to do with it. Under these circumstances, hexagonal socket head bolts are frequently adopted which allow disassembly and repair by a hexagon wrench widely used in common that is easily available. 
     Thus, the present invention aims at providing a fastening metal fitting which allows sufficient fastening by a hexalobular wrench at the time of assembly and which can be loosen or fastened by widely using not only a hexalobular wrench but also a common hexagon wrench at the time of disassembly and repair. 
     MEANS FOR SOLVING THE PROBLEM 
     In order to solve the above-described problem, the fastening metal fitting according to the present invention is formed of a head and an axial portion having a screw portion, in which formed at the center of the head is a tool insertion hole with a hexagonal socket portion and circularly-arced notched portions outwardly protruding from the respective corners of the socket portion which are provided at the corners continuously. 
     The fastening metal fitting according to the present invention has, in addition to the above-described components, either one or both of a “+”-shaped slot and a single slot formed at the bottom of the tool insertion hole. 
     In addition to the above-described components, the fastening metal fitting according to the present invention is characterized in having a head whose shape is cylindrical. 
     The bolt according to the present invention is formed of a head and an axial portion having a screw portion, whose head has a regular square shape as seen from the top which is obtained by removing, from a regular dodecagon, four triangular projections on diagonals of a vertical line and a horizontal line passing the center of the regular dodecagon and has each corner formed to have a V-shaped engaging slot left, and whose head has, at its center, a hole whose shape is regular hexagonal and which has circularly-arced notched portions outwardly protruding from the respective corners of the hole which are provided at the corners continuously. 
     EFFECTS OF THE INVENTION  
     The fastening metal fitting according to the present invention can be widely used for a common hexagon wrench or a hexalobular wrench because of a shape of a tool insertion hole. As a result, at the time of assembly of a target object, a hexalobular wrench enables satisfactory fastening to be realized and a fastening axial force to be managed with ease. On the other hand, at the time of disassembly and repair of the target object, even without a hexalobular wrench having a special shape at hand, use of a hexagon wrench widely used in common enables loosing and fastening. 
     In addition, the fastening metal fitting according to the present invention is lighter in weight than a common hexagonal socket head bolt. 
     Furthermore, the fastening metal fitting according to the present invention, when having either one or both of a “+”-shaped slot and a single slot formed at the bottom of a tool insertion hole, allows a wide use of a minus screw key and a plus screw key in addition to a common hexagon wrench and a hexalobular wrench. 
     Since the bolt according to the present invention has a head whose shape as seen from the top is regular square, at the time of assembling a target object, a rotation angle can be visually checked with ease. As a result, at the time of another fastening based on the rotation angle after primary fastening, a fastening axial force can be managed with ease. 
     The bolt according to the present invention, at its fastening or loosing, allows a wide use of a 12-point wrench, and an open-end wrench for a hexagon head bolt or a square head bolt because of its head shape, as well as allowing a wide use of a common hexagon wrench and a hexalobular wrench because of a shape of a hole at the center of the head. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a plan view of a fastening bolt according to a first embodiment of the present invention. 
         FIG. 2  is a front view of the fastening bolt. 
         FIG. 3  is a longitudinal sectional view of the fastening bolt. 
         FIG. 4  is a view for use in explaining a state where the fastening bolt is used by a hexalobular wrench. 
         FIG. 5  is a view for use in explaining a state where the fastening bolt is used by a hexagon wrench. 
         FIG. 6  is a plan view of a fastening bolt according to a second embodiment of the present invention. 
         FIG. 7  is a longitudinal sectional view of the fastening bolt. 
         FIG. 8  is a plan view of a fastening bolt according to a third embodiment of the present invention. 
         FIG. 9  is a longitudinal sectional view of the fastening bolt. 
         FIG. 10  is a plan view of a bolt according to a fourth embodiment of the present invention. 
         FIG. 11  is a front view of the bolt. 
         FIG. 12  is a view for use in explaining a state where the bolt is used by a 12-point wrench. 
         FIG. 13  is a view for use in explaining a state where the bolt is used by an open-end wrench. 
         FIG. 14  is a view for use in explaining a state where the bolt is used by a 7-point open-end wrench. 
         FIG. 15  is a view for use in explaining a state where the bolt is used by a hexagon wrench. 
         FIG. 16  is a view for use in explaining a state where the bolt is used by a hexalobular wrench. 
     
    
    
     EMBODIMENTS OF THE PRESENT INVENTION 
     In the following, embodiments of the present invention will be described with reference to the drawings. 
     As shown in  FIG. 1  through  FIG. 3 , a fastening bolt (fastening metal fitting)  1  according to a first embodiment of the present invention includes a cylindrical head  2  having a large diameter and an axial portion  4  with a small diameter which has a screw portion  3  on its circumference. At the center of the head  2 , a tool insertion hole  5  is formed. The tool insertion hole  5  is formed of a hexagonal socket portion  5   a  and circularly-arced notched portions  5   b  . . .  5   b  outwardly protruding from the respective corners of the socket portion  5   a  which are provided at the corners continuously. 
     Next, functions of the fastening bolt  1  will be described. 
     First, at the time of assembly, inserting a hexalobular wrench a into the circularly-arced notched portions  5   b  . . .  5   b  of the tool insertion hole  5  to fasten the fastening bolt  1  as shown in  FIG. 4  realizes reliable fastening. 
     On the other hand, at the time of disassembly and repair, it is possible not only to extract the fastening bolt  1  by the hexalobular wrench a but also, even without the hexalobular wrench α at hand, to execute disassembly and repair by inserting a common hexagon wrench β widely used into the hexagonal socket portion  5   a  of the tool insertion hole  5  and loosing or fastening the fastening bolt  1  as shown in  FIG. 5 . 
     Thus, the fastening bolt  1  according to the first embodiment allows a wide use of the hexalobular wrench α and the common hexagon wrench β because of a shape of the tool insertion hole  5 . As a result, a fastening axial force can be managed with ease. Moreover, the bolt can be made lighter in weight than a common hexagonal socket head bolt. 
     As shown in  FIG. 6  and  FIG. 7 , the fastening bolt  1  according to a second embodiment of the present invention has a “+”-shaped slot  5   c  formed at the bottom of the tool insertion hole  5 . The fastening bolt  1  allows a use of a plus screw key (not shown) in addition to the hexalobular wrench α and the common hexagon wrench β. 
     In place of the “+”-shaped slot  5   c,  a single slot may be formed. In such a case, a minus screw key (not shown) can be used in place of a plus screw key. 
     As shown in  FIG. 8  and  FIG. 9 , the fastening bolt  1  according to a third embodiment of the present invention has the “+”-shaped slot  5   c  and a single slot  5   d  formed together at the bottom of the tool insertion hole  5 . The fastening bolt  1  allows a wide use of a plus screw key and a minus screw key (both of which are not shown) in addition to the hexalobular wrench α and the common hexagon wrench β. 
     While in the above-described embodiments, the present invention is applied to the fastening bolt  1  with the cylindrical head  2  having a large diameter, it is not limited to such fastening bolt  1  but be widely applicable to fastening metal fittings of various shapes such as a plug and a socket screw. 
     Next, a fourth embodiment of the present invention will be described. 
       FIG. 10  and  FIG. 11  show a bolt  10  for automobiles according to the fourth embodiment of the present invention. The bolt  10  is formed of a head  11  and an axial portion  13  with a screw  12  formed on its circumference. 
     The head  11 , as shown by a virtual line in  FIG. 10 , is formed to be a regular square as seen from the top with four triangular projections A, B, C and D removed from a regular dodecagon which are on diagonals of the vertical line X-X and the horizontal line Y-Y passing the center of the regular dodecagon. Furthermore, the head  11  is formed to have V-shaped engaging slots  11   b  . . .  11   b  which allow a 12-point wrench L to fit left at the respective corners of its four sides  11   a  . . .  11   a.    
     Length of each side of the four sides  11   a  . . .  11   a  is designed to be the same as a length of one side of a head of a common hexagon bolt. 
     Formed at the center of the head  11  is a regular hexagonal hole  14  with circularly-arced notched portions  14   a  . . .  14   a  outwardly protruding from the respective corners of the hole  14  which are provided at the corners continuously. 
     Next, functions of the bolt  10  according to the fourth embodiment will be described. 
     First, at the time of fastening, the bolt  10  is fastened by a predetermined axial force by using a 12-point torque wrench L as shown in  FIG. 12 . In this case, as a 12-point torque wrench L, a manually-operated, electric-steering, or box-end wrench can be used. 
     On the other hand, at the time of disassembly and repair, the bolt  10  may be extracted by the 12-point torque wrench L, or without the 12-point torque wrench L in the mountains, the bolt  10  can be extracted by using an open-end wrench M for a hexagon head bolt or a square head bolt as shown in  FIG. 13 . 
     As shown in  FIG. 14 , the bolt  10  can be extracted also by using a 7-point open-end wrench N having seven engaging portions n . . . n. 
     Furthermore, the bolt  10  can be extracted by using a hexagon wrench S fitting the hole  14  at the center of the head  11  as shown in  FIG. 15  or by a hexalobular wrench R fitting the circularly-arced notched portions  14   a  . . .  14   a  of the hole  14  as shown in  FIG. 16 . 
     Then, also at further fastening after disassembly and repair, a wide range of wrenches can be used such as the above-described 12-point torque wrench L, open-end wrench M for a hexagon head bolt or a square head bolt, 7-point open-end wrench N, hexagon wrench S and hexalobular wrench R. 
     Then, at the time of fastening, after primary fastening executed until the bolt  10  has no clearance, fastening to a predetermined angle, for example, 120° or 180° while looking at the movement of the four sides  11   a  . . .  11   a  of the head  11  whose shape as seen from the top is regular square enables the bolt  10  to be fastened by a predetermined axial force. This enables an axial force at the time of fastening to be simply managed with ease. 
     Also because the head  11  has a regular square shape, the bolt  10  can be made lighter in weight than that whose head is regular hexagonal. 
     Although the present invention is applied to the bolt  10  for automobiles in the fourth embodiment, the invention is not limited thereto but applicable to bolts for all the other purposes.