Pierce nut manufacturing apparatus

Abstract

A pierce nut manufacturing apparatus using a nut former for forming nut blank 11 for high stress type pierce nut 1, Wherein the undercut screw-hole 12 is pierced and the end surface portion of pilot portion 13 radially widened, and the four diagonal corner end surfaces of nut blank 11 b finished with the forming process of slanting and enlarging the peripheral side wall surface of pilot portion 13 for defining annular groove 15 are pushed out by four knockout pins 77 and then pushed in between a pair of fingers 58, 58 of a transfer mechanism located in the vicinity of end surface of a die 53.

1 . A pierce nut manufacturing apparatus using a nut former for forming nut blank ( 11 ) for high stress type piercing nut ( 1 ), which is configured in that cylindrical pilot portion ( 13 ) of which an end portion thereof serves as a punch for piercing a metal plate is disposed at a central portion thereof including undercut screw-hole ( 12 ) of a square nut body, and also, protruding side wall ( 14 ) is disposed so as to surround the pilot portion ( 13 ) along the outer periphery of the nut body, annular groove ( 15 ) is formed between the pilot portion ( 13 ) and the side wall ( 14 ), and a peripheral side wall of the pilot portion ( 13 ) and the side wall ( 14 ) for defining the annular groove ( 15 ) are slanted against an axial line so that the annular groove ( 15 ) is formed to have a dovetail shape widening in the direction of depth,
 wherein the undercut screw-hole ( 12 ) is pierced and an end surface of the pilot portion ( 13 ) is radially widened, and four diagonal corner end surfaces of nut blank ( 11   b ) finished with a forming process of slanting and enlarging a peripheral side wall surface of the pilot portion ( 13 ) for defining the annular groove ( 15 ) are pushed out by four knockout pins ( 77 ) and pushed in between a pair of fingers ( 58 ,  58 ) of a transfer mechanism located in the vicinity of end surface of die ( 53 ).   
     
     
         2 . A pierce nut manufacturing apparatus using a nut former, which is configured in that knockout pin ( 62 ) is disposed in such manner as to be able to axially move forward and backward in concave ( 61 ) of die ( 52 ), into which pre-formed blank ( 11   a ) is inserted, and activated by spring ( 63 ) in the retreating position, annular protrusion ( 66 ) is disposed at the end of first cylindrical insert ( 65 ) fixedly arranged deep in the concave ( 61 ) externally of the knockout pin ( 62 ), and on the other hand, protrusion ( 68 ) for forming preliminary hole ( 12   b ) for undercut screw-hole ( 12 ) is provided at the front end of punch ( 67 ) opposing to the die ( 52 ), and the blank ( 11   a ) inserted into the concave ( 61 ) is held and pressed between the punch ( 67 ) and the knockout pin ( 62 ) in order to form preliminary holes ( 12   a ,  12   b ), not through-holes, and also, the annular protrusion ( 66 ) is pressed into blank ( 10 ), and cylindrical pilot portion ( 13 ) of which an end portion thereof serves as a punch for punching out a metal plate is disposed at a central portion including the preliminary hole ( 12   a ) of a square nut body, and also, side wall ( 14 ) is disposed protruding so as to surround the pilot portion ( 13 ) along the outer periphery of the nut body, and there are provided forming die/punch ( 52 ,  67 ) for nut blank ( 11   a ) formed with annular groove ( 15 ) between the pilot portion ( 13 ) and the side wall ( 14 ),
 and taper wall ( 75 ) widening outside is disposed at the base portion of piercing punch ( 72 ) arranged in concave ( 71 ) of die ( 53 ) for the next process into which the nut blank ( 11   a ) is inserted, annular protrusion ( 76 ) to be inserted into the annular groove ( 15 ) is disposed at the end of second cylindrical insert ( 73 ) externally of the piercing punch ( 72 ), and with the nut blank ( 11   a ) inserted and pressed in concave ( 71 ) of die ( 53 ) for the next process, due to the cooperative action of cylindrical punch ( 80 ) and the piercing punch ( 72 ), the preliminary hole ( 11   a ,  11   b ) is pierced to form undercut screw-hole ( 12 ), and an end portion of the pilot portion ( 13 ) is radially widened by the taper wall ( 75 ), a peripheral wall surface of the pilot portion ( 13 ) for defining the annular groove ( 15 ) is slanted to form the annular groove ( 15 ) into a dovetail groove widening in the direction of depth, and also, there are provided piercing and pilot portion enlarging forming die/punch ( 53 ,  80 ) configured in that an outer end periphery of the pilot portion ( 13 ) is abutted in a restraining fashion on an inner side surface of the annular protrusion ( 76 ), and knockout pin ( 82 ) activated by spring ( 83 ) in the retreating position, which is disposed in such a manner as to be able to axially move forward and backward in concave ( 81 ) of die ( 54 ) for the process after next into which the nut blank ( 11   b ) finished with piercing and enlarging pilot portion ( 13 ), taper wall ( 85 ) for slanting the side wall ( 14 ) of the nut blank ( 11   b ) toward the axial line is disposed deep in the concave ( 81 ), annular protrusion ( 87 ) to be inserted into the annular groove ( 15 ) is disposed at the end of third cylindrical insert ( 86 ) arranged at the bottom of concave ( 81 ) of die ( 54 ) for the process after next, and with the nut blank ( 11   b ) inserted and pressed in concave ( 81 ) of die ( 54 ) for the process after next by means of punch ( 88 ) opposing to the die ( 54 ) for the process after next, the side wall ( 14 ) is slanted by the taper wall ( 85 ) toward the axial line in order to form the annular groove ( 15 ) into a dovetail groove widening in the direction of depth, and there is also provided side wall ( 14 ) slanting forming die/punch ( 54 ,  88 ) having such a configuration that an inner end periphery of the side wall ( 14 ) slanted toward the axial line is abutted in a restraining fashion on an outer side surface of the annular protrusion ( 87 ),   wherein the piercing punch ( 72 ) and the second cylindrical insert ( 73 ) of the piercing and pilot portion enlarging die/punch ( 53 ,  80 ) are securely held in concave ( 71 ) of die ( 53 ) for the next process, and four knockout pins ( 77 ) are provided so as to surround the piercing punch ( 72 ), and with the nut blank ( 11   a ) inserted and pressed in concave ( 71 ) of die ( 53 ) for the next process, due to the cooperative action of the cylindrical punch ( 80 ) and the piercing punch ( 72 ), four diagonal corner end surfaces of the nut blank ( 11   b ) finished with piercing the undercut screw-hole ( 12 ) and enlarging the pilot portion ( 13 ) are pushed out by the four knockout pins ( 77 ) and are pushed in between a pair of fingers ( 58 ,  58 ) of a transfer mechanism located in the vicinity of end surface of the die ( 53 ).   
     
     
         3 . The pierce nut manufacturing apparatus of  claim 2 , wherein the piercing punch ( 72 ) and the second cylindrical insert ( 73 ) are securely held via holder ( 74 ) in concave ( 71 ) of die ( 53 ) for the next process, and the four knockout pins ( 77 ) are disposed in such a manner as to be able to axially move forward and backward in the holder ( 74 ) in phase of 90 degrees around the piercing punch ( 72 ), which are activated by spring ( 78 ) in the retreating position, and when in the retreating position, the front end surface thereof is flush with the front end surface of the second cylindrical insert ( 73 ), and in the mode of moving forward, the pins are abutted on four diagonal corner end surfaces of the nut blank ( 11   b ), and then the nut blank ( 11   b ) is pushed out and pushed in between the pair of fingers ( 58 ,  58 ).