GB921431A - Improvements in or relating to the manufacture of ball studs - Google Patents

Abstract

921,431. Forging; extruding. THOMPSON RAMO WOOLDRIDGE Inc. Jan. 15, 1962, No. 1442/62. Classes 83 (2) and 83 (4). A method of forging a ball stud comprises forming a part spherical head on one end of a blank, displacing a central portion of said head to form a cup shape, and forming the latter into a hollow substantially closed spherical head. In a first embodiment, a cylindrical blank 18 is forced into a die 19 by a ram 28, thus forming the ball-stud exterior with the exception of the outermost hemisphere of the head 15 (Fig. 6). In a second operation (Fig. 3, not shown), the raised portion in the outer end of the stud formed by the recess 29 in the punch 28 (Fig. 2) has formed in it a concave recess. In a third operation (Fig. 4, not shown), the concave recess is deepened by a convex-ended conical punch to the form shown in Fig. 5. In the final operation, the hollow punch 48 curls the cylindrical side of the head to form the hollow sphere 15 in Fig. 6. In a second embodiment (Figs. 7 to 11, not shown) a ball stud of modified head cavity shape is formed in three operations, by combining the operations of Figs. 2 and 3 of the first embodiment. The forging, which is a cold operation, is facilitated by the use of specified lubricants and the hollow punch for conducting the final " curling " operation may have a bore for feeding lubricant into the cup-shaped head. Also, the shallow recess formed in the blank end prior to cupping may act as a reservoir for lubricant in addition to its prime function of centring the punch. In its finished form, the stem 11 of the ball stud will be threaded, e.g. by rolling. The punches may be made of hardened steel, and ball studs can be produced from cold worked blanks of steel.