Patent GB-974559-A (GB)
IPC: B21D53/20
Abstract: 974,559. Washers. E. JORDAN. Oct. 29, 1963 [Nov. 7, 1962], No. 42520/63. Heading F2H. [Also in Division B3] A method of producing metal helical locking washers having internal teeth inclined so as to form forward and rearward edges projecting from opposite faces of the washer, the rearward edge of one tooth overlapping the forward edge of the next tooth comprises feeding a continuous strip of spring material, slitting it inwardly from one edge thereof at spaced intervals and bending to a similar inclined position each of the teeth thus formed between consecutive slits with the forward and rearward edges projecting respectively from opposite sides of the strip, notching the strip from the same edge at intervals embracing a plurality of teeth, coiling the strip edgewise into a helix with the toothed edge internally of the helix and dividing the helix into individual washer portions at the weak portion formed by the notch. Two strips of material enter a housing 45 of a combined slitting and bending tool, pass over a table 23 and between side positioning rollers 26-33 and grooves 24, 25, between a pair of gear driven rolls 19, 20 having interengaging profiled peripheries through a pair of straightening rolls 34, 35 to a pair of gear-driven wrapping mandrels 36, 37 which may also co-operate with a parting roller 38. The rolls 19, 20 have tool rims 69, 70 and the rolls 34, 35 stepped grooves 71-74 and all run at the same peripheral speed. The mandrels 36, 37 may also run at the same speed but if the roller 38 is also used it is rotated faster than the mandrels. Guide members 75, 76 having slit-shaped guideways 81 and curved deflectors 77, 80 engage the outer edges of the strips to bend and downwardly deflect the strips into a helical form. If the distance between the rolls 34, 35, and mandrels 36, 37 is in excess of the strip length required to form a washer portion and the mandrels have a higher peripheral speed than the rolls then the tension produced in the strip snaps the washer portions at the notches and the portion is coiled about one of the mandrels from which it freely falls. Alternatively, if the roller 38 is used and the mandrels and rolls have the same peripheral speeds and are spaced less than a washer portion strip length apart then the roller 38 operating at a greater peripheral speed than the mandrels snaps the strips at their parting points by axial pressure applied as each washer has been coiled about one of the mandrels. The roller 38 which serves both mandrels has a grooved periphery 86 wider than the strip width and is displaced in a plane lower than the feed path and may be tilted at an angle corresponding to the helix angle of the washer. The shaft 66 on which the roller 38 is mounted may be fitted with springs to force the roller towards the mandrels to assist in the parting operation. The body of the formed strip is positively nipped between the narrow bight portion of the rolls 34, 35 formed by the aligned grooved peripheries thereof whilst the bent teeth 6 of the strip move through the wider bight and are aligned by the action of the faces 92, 93. The slitting and bending teeth of the roms of the rolls 19, 20 are of a triangular form, arranged transversely and the circumference of the rolls is equal to e.g. a length of strip required to make four washers. Triangular portions 17, 18 of material adjacent to the notch slit are bent in opposite directions to form wing portions 12, 13. The washers are subsequently hardened or if produced in a length are hardened and subsequently snapped therefrom. The length of the washer portion may be such that it subtends an angle between 340 degrees and 380 degrees.