GB562936A - Improved method and apparatus for winding multi-helical metal coils - Google Patents

Abstract

562,936. Coiling springs. EDWARDS, L. W. C. March 18, 1943, No. 4440. [Classes 83 (ii) and 83 (iv)] An apparatus for .making multi-helical bimetallic elements for temperature-responsive indicating and measuring devices, with a helix of small diameter lying within a second helix of larger diameter by feeding a bi-metallic strip into grooved discs at angles which determine the pitch of the helices, comprises a pivoted tool adapted to hold a formed helix so that when it is turned into another position the helix takes up a different angle relatively to the direction of feed during formation of the helix so that a set is given to the strip close to the end of the helix and thus on the strip being fed to a succeeding die a further helix of different pitch is formed coaxial with the preceding helix. The smallest helix may be an axial extension of instead of lying within the helix of next smallest diameter so as to serve merely for attachment to the indicator shaft. A bi-metallic strip 20 may be fed by rolls 21, geared together and coupled to a reversible drive, through a guide 22 to an indexing turntable 23 which carries seven tools A-F, set in position successively by the engagement of a latch 29 with notches 30. The strip is first coiled on a mandrel 36 removably mounted in ' a pair of rectangular bars 31, 32 constituting the tool A, the bar 32 having a stepped end provided with a semicircular groove 35 and with a guide plate 38 fixed to and projecting above the side of the tip of the bar. After, say, 1¢ turns have been wound, as indicated by a fixed pointer 26 co-operating with a scale 25 on the upper rock-shaft, the feed is stopped, the mandrel 36 withdrawn, feed reversed to retract the formed helix, and the table rotated to bring the tool B into position. The tool B, which has an oblique step 44 is pivoted to the table at 41 so that it rests against either of the stops 45, 46. With the tool B engaging the stop 45, the strip is again fed forward until the formed helix is in alignment with the mandrel axis, whereupon the mandrel 42 is inserted in the tool and passed through helix. The tool is then moved on its pivot against the stop 46.so as to deform the strip angularly in its own plane to reduce the helix lead angle to suit the pitch of the second helix and the strip is fed about half a turn to effect the transition from the first to the second helix. The mandrel 42 is then withdrawn and the feed mechanism run back so as to draw the helix clear of the tool B and the table is turned to bring the tool C into working position. This tool has a removable mandrel 47 coaxial with a forming groove 49 and with an extension 48 to fit within the first helix. Further, it has a guide plate 50 with a bevelled working edge to suit the helix angle of the second helix. The strip is fed into the tool C so as to form the second helix, the spiral transition between the first and second helices being at the same time completed, if not completed by the tool B. The tool D is next brought into position. This is provided with a groove 52 of semicircular section and of a diameter intermediate between those of the second and third helices. The strip is fed thereinto to about one half of a turn to form part of the spiral transition and effect part of the reversal of the helix lead angle. A tool E, similar to tool C but inclined in the opposite direction with respect to the strip feed, is then brought into position to form the third helix of opposite hand to the second helix. Tool F similar to tool D next forms a transition of larger diameter and a tool G similar to tool C then forms a fourth helix. The pivoted transition tool B may be dispensed with, the tool C being pivoted on the table to effect also the transition operation. Specification 403,920 is referred to.