Patent GB-1098632-A (GB)
Title: Automatic transfer mechanism for press line
IPC: B21D43/10
Filed: 1965-03-17
Abstract: 1,098,632. Transferring blanks; metal working presses; stamping. DANLY MACHINE SPECIALITIES Inc. March 17, 1965 [March 26, 1964], No. 11384/65. Headings B3H, B3Q and B3W. [Also in Divisions B8 and G3] In a press-line for performing a series of successive operations on a workpiece there are a plurality of reciprocating presses A, B, C, Fig. 1, each having a variable speed drive motor 20, transfer means 41, 42 at the input and output sides of each press, and synchronizing means for continuously varying the drive speeds so that the presses are operated with their drive shafts in substantial synchronism, each of the transfer mechanisms being directly coupled to the drive shaft of an associated press. Press drive synchronizing mechanism, Figs. 14 and 15 (not shown).-A timing motor M drives transmitting synchros TA, TB, TC at a constant but adjustable speed. Receiving synchros RA, RB, RC associated with the presses A, B, C produce an output signal which depends in magnitude and phasing on the variation of any of the presses from the desired speed and phase position. The output signal is fed to a discriminator, a magnetic amplifier and then to a power amplifier, which controls the current fed to the slip-rings 28 of the press clutch. Drive to transfer mechanisms.-The input and output transfer mechanisms are similar, the following description refers to the loading mechanism of press A. A bracket 45 is slidably mounted on a post 46 on the press and has rails which support and guide a carrier (60), Fig. 10 (not shown), so that it is free to move horizontally along the bracket towards and away from the working area of the press. A hollow square post 70 is guided for vertical movement in the carrier and has mounted at its lower end an arm 50 which carries a work gripper. Vertical and horizontal movements of the transfer mechanism are obtained from a pair of cams 81, 82, Fig. 3, which are driven by gearing from the main shaft 27 of the press. The cam 81 co-operates with a roller follower on a lever 84 which is pivotally mounted at its upper end and at its lower end is connected by a yoke 86 to the post 70, so that oscillation of the arm produces horizontal movement of the carrier. As a safety measure the cam follower roller is maintained in contact with the cam 81 by a pneumatic cylinder which yields if the movement of the carrier is obstructed. The cam 82 operates a rocker arm 94 which oscillates a bevel gear 104. This gear is fixed to a splined shaft 100 on which slide a pinion 110. A rack 115 on the post 70 meshes with the pinion so that as the cam 82 rocks the lever 94 the post 70 reciprocates vertically. Construction of work grippers.-Each gripper, Fig. 6, comprises a body 200 which clamps on to the arm 50 and a jaw extension 201 slidably mounted on posts 202 and carrying first jaw elements 203. A second movable jaw 206 is mounted on an arm 205 which is pivotally attached to the jaw extension 201. A link 215 connects the arm 205 to a block 212 slidably mounted on jaw extension 201. A spring 216 pressing against the block 212 biases the jaw 206 to the open position. A pneumatic ram reciprocates the block 212 so that when the ram moves outwardly the jaw extension 201 is is first projected outwardly and then the jaw 206 closes on to the jaw 203. Conveyer mechanism for moving workpieces from the output of one press to the input position of the following press, Fig. 12. Each conveyer comprises a frame 136 and two parallel sprocket chains supported on sprocket-wheels 141, 142. The chains carry work-holders which are spaced apart by a distance d, which is the distance that the conveyer moves for each cycle of the presses. In Fig. 12, two sets of workpiece holders 381, 382 are shown, the holders of each set being spaced apart by the distance d. The provision of two sets of work-holders facilitates changing the line to suit a different component. The drive to the conveyers is shown in Fig. 3 and comprises a shaft 171 driven by gearing from the mainshaft of the press, and driving shafts 174, 177 which in turn drive two cams 181, 182. The cams each have a three-legged follower 183, 184 which are secured to an output shaft 185 which drives the chain sprockets through gears 186, 187. The cam profile is such that the conveyer dwells during 50% of the cycle time. Operation.-At the end of a working stroke of the presses the output transfer mechanisms operate to remove the workpieces from the press and place it on the conveyer. The input transfer mechanisms remove a workpiece from the conveyer and transfer it to the working area of the press. The path of movement of the work grippers is determined by the profiles of the cams 81, 82. In a modification, Fig. 18 (not shown), the conveyers are omitted and each arm (450) carries two work grippers (451) and (461). The workpieces are transferred between the presses along the paths (491, 492, 493, 494), there being a stationary pedestal at the junction of each two paths where the workpiece rests until the next cycle. In a further modification the pedestals are omitted and the workpiece is passed directly from the gripper (461) associated with one transfer mechanism to the gripper (451) associated with the following transfer mechanism.