GB635564A - Method and apparatus for rolling screw threads on rods, bolts or the like - Google Patents

Abstract

635,564. Rolling screw threads. LANDIS MACHINE CO. Dec. 3, 1946, No. 35810. Convention date, Jan. 16. [Class 83 (iv)] A method of forming a screw thread on a blank comprises feeding the blank between a pair of rolls rotating at the same speed and in the same direction and having thread-forming serrations extending partially around their peripheries such that there is a substantially equal progressively increasing displacement of the metal of the blank during a partial revolution of the rolls followed by a finishing of the thread during the continued revolution of the rolls. Two co-operating rolls 28, Fig. 1, driven in the same direction each comprise a workfeeding notch 38, a plain cylindrical portion 39 and screw-thread forming portion 40. In the case of the upper roll, the portion 40 begins at the notch 38 with a diameter equal to that of the plain portion 39 and increases in diameter up to a part of substantially uniform diameter terminating approximately 180 degrees from the notch. In the case of the lower roll, the threaded portion begins opposite and ends at the notch. In operation a cylindrical blank 46 is placed in a hopper opening 88 adjacent the upper roll and during the rotation of the roll it falls into the notch 38 and is carried into the position between the rolls, as shown. In this position it is rolled between the portions 40 to form the thread and is then picked up by the notch 38 of the lower roll and carried to a discharge position. A fresh blank may be put into the hopper 88 at each rotation of the roll. As shown in Fig. 2, two sets of rolls may be used to form screw threads at both ends of a blank, the threaded portions of the two sets of rolls being relatively displaced by 180 degrees so that the two ends are not rolled at the same time. This arrangement would allow the two ends to have threaded portions of different diameters or with threads of different pitch and lead. In the rolling position, the work is positioned between guides 48, 52, the blade 48 being adjustable and capable of being set at an angle to form conical work-pieces. In a modified form, Fig. 15, blanks on a shoot 124 are positively fed into the notch of the upper roll by plunger 114 operated from a cam on the roll shaft. The guide 52 is replaced by the member 132 shaped as at 136 so as positively to feed the blanks out of the notch and into rolling position between the two rolls. A member 176 pivoted to a rod 172 which is reciprocated against the action of a spring 168 from a cam 138 on the shaft of the lower roll ejects the finished articles from the rolling position into the notch of the lower roll.