Method for manufacturing stainless steel ball stud for automotive suspension system

Abstract

Provided is a method for manufacturing a stainless steel ball stud for an automotive suspension system, which includes: a forging and molding step of forging and molding a cylindrical shaped stainless material blank with the same top and bottom diameters by using a progressive press machine to operate a number of mold dies simultaneously and to move a forged mold product of a preceding die to a succeeding die, to make a forged mold product; a male thread shaping step of shaping a male thread on the forged mold product; and a cutting and surface finishing/burnishing step of cutting the forged mold product by using one ball stud processing machine such that a head part is cut at exact dimensions, a neck part and a washer part are shaped and the surface finishing/burnishing work to the head part is performed to complete the stainless steel ball stud for an automotive suspension system.

1 . A method for manufacturing a stainless steel ball stud for an automotive suspension system, in which the stainless steel ball stud ( 10 ) is shaped with a head part ( 11 ) in a ball shape, a recessed neck part ( 12 ) under the head part ( 11 ), a washer part ( 13 ) at a lower end of the neck part ( 12 ), a straight line part ( 14 ) under the washer part ( 13 ) and having a smaller diameter than the washer part ( 13 ), a tapered part ( 15 ) under the straight line part ( 14 ) and having a diameter which gradually becomes narrower downwardly, a male thread part ( 16 ) under the tapered part ( 15 ) and having a smaller diameter than the lower end of the tapered part ( 15 ), a dog point part ( 17 ) under the male thread part ( 16 ) and having a smaller diameter than the male thread part ( 16 ), and a hex socket ( 18 ) formed into a bottom of the dog point part ( 17 ), the method comprising:
 a forging and molding step of forging and molding a cylindrical shaped stainless material blank with the same top and bottom diameters by using a progressive press machine to operate a number of mold dies simultaneously and to move a forged mold product of a preceding die to a succeeding die, to make a forged mold product ( 106 );   a male thread shaping step of shaping a male thread on the forged mold product ( 106 ); and   a cutting and surface finishing/burnishing step of cutting the forged mold product ( 106 ) by using one ball stud processing machine ( 100 ) such that the head part ( 11 ) is cut at exact dimensions, the neck part ( 12 ) and the washer part ( 13 ) are shaped and the surface finishing/burnishing work to the head part ( 11 ) is performed to complete the stainless steel ball stud ( 10 ) for an automotive suspension system.   
     
     
         2 . The method for manufacturing a stainless steel ball stud according to  claim 1 , characterized in that the forging and molding step manufactures the forged mold product ( 106 ) which is shaped with a ball-shaped head part ( 104   a ), a pre-neck part ( 103   b ) arranged in a vertical shape under the ball-shaped head part ( 104   a ), a vertical part ( 101   a ) under the pre-neck part ( 103   b ) and having a smaller diameter than the pre-neck part ( 103   b ), a tapered part ( 106   a ) under the vertical part ( 101   a ) and having a diameter which becomes gradually narrower downwardly, a pre-male thread part ( 102   a ) under the tapered part ( 106   a ) and having a smaller diameter than a lower end of the tapered part ( 106   a ), a dog point part ( 104   b ) under the pre-male thread part ( 102   a ) and having a smaller diameter than the pre-male thread part ( 102   a ), and a hex socket ( 105   a ) at the bottom of the dog point part ( 104   b ). 
     
     
         3 . The method for manufacturing a stainless steel ball stud according to  claim 2 , characterized in that the forging and molding step comprises a six (6)-step molding process such that the cut material is moved to a first mold die, a first mold product ( 101 ) is moved to a second mold die, a second mold product ( 102 ) is moved to a third mold die, a third mold product ( 103 ) is moved to a fourth mold die, a fourth mold product ( 104 ) is moved to a fifth mold die, a fifth mold product ( 105 ) is moved to a sixth mold die, and a sixth mold product ( 106 ) is discharged to the outside. 
     
     
         4 . The method for manufacturing a stainless steel ball stud according to  claim 3 , wherein the forging and molding step comprises:
 a first molding process to mold, in a first mold die, a first mold product ( 101 ) that includes the generally vertical part ( 101   a ) with a top and bottom having the same diameter, and a rounded bottom end with a smaller diameter, by using the material blank of a certain length which has a top end and a bottom end with the same diameter;   a second molding process to mold, in a second mold die, a second mold product ( 102 ) in which the pre-male thread part ( 102   a ) positioned at a lower section of the vertical part ( 101   a ) is in a vertical shape with a smaller diameter than the vertical part ( 101   a ) and the vertical part ( 101   a ) is connected to the pre-male thread part ( 102   a ) in a hemispheric shape, by using the first mold product ( 101 );   a third molding process to mold, in a third mold die, a third mold product ( 103 ) in which a pre-head part ( 103   a ), which is tapered to have an upper end with a greater diameter than a lower end, and the pre-neck part ( 103   b ), which is in a vertical shape with a greater diameter than the vertical part ( 101   a ), are positioned in an upper section of the vertical part ( 101   a ), and the pre-head part ( 103   a ) and the pre-neck part ( 103   b ) are connected to be tapered such that a diameter becomes narrower downwardly, by using the second mold product ( 102 );   a fourth molding process to mold, in a fourth mold die, a fourth mold product ( 104 ) in which the ball-shaped head part ( 104   a ) is shaped in the pre-head part ( 103   a ), the dog point part ( 104   b ) in a vertical shape with a smaller diameter than the pre-male thread part ( 102   a ) is shaped in a lower section of the pre-male thread part ( 102   a ) and a pre-hex socket part ( 104   c ) is shaped at a lower end of the dog point part ( 104   b ), by using the third mold product ( 103 );   a fifth molding process to mold, in a fifth mold die, a fifth mold product ( 105 ) in which the hex socket ( 105   a ) is shaped at the lower end of the dog point part ( 104   b ), by using the fourth mold product ( 104 ); and   a sixth molding process to mold, in a sixth mold die, a sixth mold product ( 106 ) in which the tapered part ( 106   a ) is shaped in a lower section of the vertical part ( 101   a ), by using the fifth mold product ( 105 ).   
     
     
         5 . The method for manufacturing a stainless steel ball stud according to  claim 1 , wherein the cutting and surface finishing/burnishing step comprises:
 a first cutting process to cut the ball-shaped head part ( 104   a ) of the forged mold product ( 106 ) at exact dimensions to shape the head part ( 11 ) by using a first cutter ( 310 ) of the ball stud processing machine ( 100 );   a second cutting process to cut the pre-neck part ( 103   b ) of the forged mold product ( 106 ) by using a second cutter ( 320 ) of the ball stud processing machine ( 100 ), to shape the neck part ( 12 ) and the washer part ( 13 ); and   a surface finishing/burnishing process to finish/burnish the ball-shaped head part ( 104   a ) by using a surface finishing/burnishing tool ( 330 ) of the ball stud processing machine ( 100 ).   
     
     
         6 . The method for manufacturing a stainless steel ball stud according to  claim 5 , wherein the cutting and surface finishing/burnishing step is performed by the ball stud processing machine ( 100 ) comprising:
 a holding unit ( 200 ) in which a chuck ( 204 ) is rotatably connected to a headstock ( 202 ), jaws ( 206 ) are mounted on the front of the chuck ( 204 ) such that a holding groove ( 208 ) to receive and hold the ball stud ( 10 ) is formed at the center of the chuck ( 204 ); and   a tool unit ( 300 ) in which a turret ( 304 ) is connected to a main body ( 302 ) enabling a position change, a plurality of attachment apertures ( 306   a )( 306   b )( 308 ) are formed in the front of the turret ( 304 ) such that the first cutter ( 310 ), the second cutter ( 320 ) and the surface finishing/burnishing tool ( 330 ) are securely held in the attachment apertures ( 306   a )( 306   b )( 308 ), respectively.   
     
     
         7 . The method for manufacturing a stainless steel ball stud according to  claim 6 , wherein the surface finishing/burnishing tool ( 330 ) of the tool unit ( 300 ) comprises:
 a tool holder ( 332 ) to be mounted in the attachment aperture ( 308 ) of the turret ( 304 );   a carbide wheel ( 334 ) to finish/burnish the surface of the ball-shaped head part ( 104   a ) of the forged mold product ( 106 ); and   a shaft ( 336 ) to connect the tool holder ( 332 ) and the carbide wheel ( 334 ).   
     
     
         8 . The method for manufacturing a stainless steel ball stud according to  claim 6 , wherein the ball stud processing machine ( 100 ) further comprises: a control unit ( 420 ) controlling the holding unit ( 200 ) and the tool unit ( 300 ) simultaneously to operate a first driving unit ( 430 ) and a second driving unit ( 440 ), the first driving unit ( 430 ) operates a motor ( 450   a ) to drive the holding unit ( 200 ) such that the holding unit ( 200 ) rotates as programmed, and the second driving unit ( 440 ) operates a motor ( 450   b ) to drive the tool unit ( 300 ) such that the tool unit ( 300 ) changes in operative position in order of the first cutter ( 310 ) to cut the ball-shaped head part ( 104   a ), the second cutter ( 320 ) to cut the pre-neck part ( 103   b ) and the surface finishing/burnishing tool ( 330 ) to process the surface finishing/burnishing of the ball-shaped head part ( 104   a ) as programmed.