ES357439A1 - Spring forming apparatus and process - Google Patents

Abstract

A method of forming a spring from a wire comprises first uniformly circumferentially stressing the wire and secondly controlling the shape assumed by the stressed wire. Apparatus for carrying out the method is in the form of a dual machine for winding clockwise and anticlockwise springs and each includes a vertical straightener 27, horizontal straightener 28, electrically driven feed rollers 32, 33 for pulling the wire 18 off a spool 24 and coiling the wire into three or four loops within a housing 36 wherein a sensing arm 40 controls the speed of the feed rollers so that the wire is fed at a constant rate to a spring forming mechanism 50. From the housing 36 the wire passes through table 22 via shoot 45 and is lapped around a grooved wheel 46 and through a guide 18 to the mechanism 50 supported on the table 22. The mechanism 50 comprises an upper and lower platen 52, 53 respectively and an oil tray 54 which rotate in unison with respect to a base 51 under power supplied by motor 60 via belt and sprocket gearing. A tubular shaft 55 is suspended from the platen 53 and receives the wire guide 18 so that rotation of the platen shaft and guide imparts a longitudinal twist to the wire. Extending upwardly from the platen 52 is a stanchion 59 about which the spring is guided and which is geared to remain stationary with respect to the base 51 despite rotation of the platen 52. Also extending from the top of platen 52 are a feed wheel 57 and a bias wheel 58 embraced by a band 145 the feed wheel rotation being generated by the rotation of platen 52 in a planetary gear system whose ratio can be adjusted to alter the number of revolutions of the platen 52 for each revolution of the feed wheel 57. The wire from the guide 18 passes through the lower and upper platens 53, 52 via oil proof couplings and is directed into a groove 140 in the feed wheel 57 where it is trapped by the band 145. A scraper 146 keeps the band clean and scrapers 148, 149 keep the grooves in the feed wheel free from dirt. As it passes from the feed wheel 57 the wire tends by itself to form into a coil or spring around the stanchion 59 the diameter of the coil being restrained by adjustable guide rollers 161, 162 and 163 (Fig. 8). Rollers 167 and 168 act as pitch controllers. Coil rotational sensing plates 175 co-operating with an electronic sensor 180 control the planet gearing to correct for any undesired rotation of the spring as it is being formed. In a modification the mechanism 50 may include means for winding springs having variations in pitch and/or diameter (Fig. 15). Such means include a cam 208 (Fig. 12) mounted on the shaft of the feed wheel 57 said cam through lever mechanism adjusting the position of the control roller 1631 mounted on a rocker arm 202. The pitch control roller 1681 is similarly controlled from a cylindrical cam 220 on the feed wheel 57.