Patent GB-1198135-A (GB)
Title: Wire Tensioning and Tying Device
IPC: B21F15/00
Filed: 1967-10-25
Abstract: 1,198,135. Wire tensioning devices. GERRARD WIRE TYING MACHINES CO. PTY. Ltd. 25 Oct., 1967 [26 Oct., 1966], No. 48580/67. Heading F2G. A wire tensioning and tying device includes drive means adapted for continuous operation in one direction, tensioning mechanism for engaging a leading end portion of a wire loop and being operable by the drive means to move that end portion in a direction so as to draw the loop about a bale, a gripper assembly for holding the opposite trailing end portion of the loop during said movement of the leading end portion thereof, and a tensioning mechanism clutch for automatically disengaging the drive connection between the drive means and the tensioning mechanism when the loop is tensioned to a predetermined degree, the clutch including a rotatable cam plate drivably connected to the tensioning mechanism and a cam bar extending transversely to the axis of rotation of the cam plate and being drivably connected to the drive means for rotation about said axis of rotation of the cam plate; the cam plate has at least one radially extending recess formed in the face thereof, and the cam bar is engageable within the or each recess for drivable connection with the cam plate to cause rotation thereof when the drive means is actuated. There is also twisting mechanism operable by the drive means to twist two tie portions of the loop located sideby-side and adjacent the leading and trailing end portions of the loop, respectively, and a twisting mechanism clutch operatively connected to the tensioning mechanism clutch so as drivably to connect the twisting mechanism to the drive means in response to disengagement of the tensioning mechanism clutch. As shown, an electric, hydraulic, or pneumatic motor is mounted in a housing 3 and through a pinion 14 and gear 17, or, alternatively, a chain, belt or friction drive, rotates a shaft 18 formed in two sections 18a, 18b connected by a clutch comprising a cam plate 19 rotatably mounted on the section 18b drivably connected to shaft section 18a through dogs 21 and drivably engageable with a cam bar 22 on the section 18b, the plate having inner and outer annular tracks 23, 24 formed with cam recesses in which lugs 29, 28 of the cam bar may engage. Adjustable pressure is applied to the cam bar by a push rod 31 acted on by a spring 36. A capstan 41 formed with circumferentially spaced slots 47 is rotatable through a one-way clutch and bevel gears 54, 56 from the shaft section 18a, and, for holding the wire in alignment with the twister mechanism and a gripper assembly, a pivotally mounted latch member 57 is provided. The gripper mechanism for releasably clamping the trailing end portion of the wire loop consists of a stationary gripper base-plate 64 and a relatively movable wheel 68 eccentrically mounted on a pivot pin 69, the wheel, as the wire is pulled between the plate and wheel, being carried towards the plate, but a spring influenced, pivoted, control arm 74 having a lug extending through one of three holes provided in the wheel 68 may be provided to urge the wheel into the wire-clamping direction; gripper release means may also be included. A wire twisting mechanism comprises an interchangeable twister element 84 having secured thereto a pinion 98, Fig. 7, driven, via an intermediate gear 99, by a gear 101 on the shaft 18 and provided with a slot 86. Operatively connected to the tensioning mechanism is a clutch whereby the element 84 is actuated only after a predetermined tension is obtained in the wire loop and this consists of a pair of co-operable rachet discs 102, 103 mounted on the shaft 18 and respectively secured to the cam bar 22 and gear 101. The element 84 is located in the wirereceiving position thereof by spring-loaded plungers, Fig. 17 (not shown) locating in recesses formed in opposite faces of the gear 99. For severing the tied loop of wire from a supply source and the surplus end portion of the loop two pivoted cutters 114, Fig. 20, are provided these being formed with blades 118 and influenced upwardly clear of the wire by spring 120; the lower surface of each wire guide slot 97 in the guide plates 96 forms an anvil or stationary cutter blade for the adjacent cutter. For actuating each cutter a bar extending from the cutter arm 116, is engageable by a detent 122 movable with the spindle 106 on which the gear 99 is mounted. In operation, after the formation of a loop around a bale, the leading end of the wire is located beneath the gripper wheel 68, through the element 84, between two pairs of capstan teeth 48 and beneath the latch 57 after which the motor is actuated to cause the end of the wire to be wound around the capstan 41. The trailing end of the wire is moved laterally into the slot 86 of the element 84 and in doing so the control arm 74 is moved upwards to lift the wheel 68 and to allow the wire to be located between the wheel and the plate 64. At this stage the leading and trailing end portions of the wire lie side by side in the slot 86. Opening of a valve causes operation of the motor to rotate shaft section 18b whereby the capstan is rotated to tension the wire, the gripper surfaces functioning to prevent longitudinal movement of the trailing end of the wire. Upon the attainment of a predetermined tension in the wire the lugs 28, 29 of cam bar 22 ride out of the recesses in cam plate 19 so that the cam bar 22 and push rod 31 are moved axially relatively to the shaft 18 against the pressure of the spring 36, whereby rotation of the capstan 41 ceases; reversal of motion of the capstan is prevented by the one-way clutch associated therewith. With the cam bar 22 disengaged and rotating with the shaft section 18b, the ratchet discs 102, 103 being then engaged together, the gear 101 is rotated to cause rotation of the twister element 84 whereby the tie portions of the wire to be twisted about each other and the cutter detents 122 are moved away from the abutment lugs 123 on the cutter bars 119, the detents, after one revolution of the shaft 106, engaging the lugs to cause downward movement of the cutter arms 116 whereby the cutters 114 simultaneously sever the leading and trailing portions of the wire. Resistance to turning movement by the capstan is released and the push-rod 31 re-engages the lugs 28, 29 with the recesses in the cam plate 19 to cause disengagement of the ratchet discs 102, 103 and cessation of rotation of the gear 101 and pinion 98.