Patent GB-781465-A (GB)
Title: Improvements in or relating to positioning, assembling or manipulating apparatus
IPC: B25J5/04
Filed: 1954-03-29
Abstract: 781,465. Screwing-up nuts; programming for machine-tools; chucks; riveting. KENWARD, C. W. June 7, 1955 [March 29, 1954; Feb. 22, 1955], Nos. 9171/54 and 5215/55. Classes 83 (3) and 83 (4). [Also in Group XXX] Manipulating, positioning or assembling- apparatus controlled by electrical signals from a record comprises a work-gripper 9 having at least five degrees of freedom of movement (linear or angular), means for driving the gripper in each degree of freedom, means for reproducing the signals from the record and means for controlling the driving-means by the signals. As illustrated, the gripper is carried by an articulated-arm comprising relatively-rotatable limbs 3 ... 7, and is rotatable in the limb 7 by an hydraulic motor 53, jaws 46 of the gripper being operated through links 56 and a movable hydraulic-cylinder 42 to grip the work. The limb 3 is rotated in a support 1 by an hydraulic servomotor 13, and the position of the arm preferably communicated to an amplifier by " answer "-signals, e.g. from a potentiometer 14, in response to reference-signals fed to the potentiometer from the record. The record also supplies the amplifier with informationsignals relating to the desired positions of the limb 3, and any " error " signals resulting in the amplifier from these two channels of opposite pole, full-wave rectified signals are fed to solenoid valves controlling the servomotor. For the pivotal connection between limbs 4, 5, error-signals to solenoid-valves 23 open one of them, allowing the hydraulic liquid from the adjacent side of a servo-valve 20 to escape along a return passage 30 and the valve to connect the hydraulic supply to the appropriate side of the servomotor which controls pivotal movement of the limb 5 about the axis of the valve 20 through 180 degrees. After approximate positioning of the limb 5, effected with the assistance of answer-signals from a half-ring potentiometer 26, fine adjustments are effected with a full-ring potentiometer 27, the wiper 29 of which is supported from a part 45 carried by the limb 6 and driven through antibacklash, step-up gearing 28, different channels on the recording supplying the coarse and fine adjustment information signals. Similar potentiometers and electro-hydraulic servo-systems control rotation of limb 6 about the axis of limb 5, limb 7 about an axis perpendicular to the latter axis, and gripper 9 in the limb 7. The jaws 46 are closed on the work under the control of a solenoid-operated servo-valve 25, and the gripper 9 is held in the motor-spindle by a spring-catch 39 which engages behind a peg 8 on the gripper. Electric supply or signals may be fed to the work-head through rings 62, brushes 61 and spring-loaded contacts 60 for position-checking, screwing-up or, when an electromagnet is used, picking-up. Screwing-up nuts. Components may be picked up from a belt a<SP>2</SP>, Fig. 3, and assembled on a belt b2, nuts being offered-up to screws during the operation by the gripper shown in Fig. 2, and rotated anti-clockwise until the starts of the co-operating threads are aligned, this being signalled by a forward movement of the main part 73 of the head in relation to the shank 74, separating contacts 60c, 70. The direction of rotation is then reversed, to screwup the nut. Assembling. When used for checking the position of an assembled component, the gripper of Fig. 2 is offered up to the position the component should occupy. Correct positioning of the component is indicated by the closing of contacts 60b, 71a, 60c, 70, and incorrect positioning by all or none of the contacts 60a ... 60c, 70, 71a, 71 closing. If the component is incorrectly positioned, the record may be reversed automatically to disassemble and then re-assemble the component or a replacement, or the apparatus may be stopped. The assembling arms illustrated in Fig. 3 are carried by a mounting c controlled by an hydraulic servomotor d and a potentiometer for rotation on a post e which is vertically-adjustable in a carriage f by a rack-and-pinion driven by a shaft c.<SP>2</SP> The carriage is movable along a cross-beam g which slides along parallels g2, g<SP>3</SP>, the torque on shaft c<SP>2</SP> due to the weight of the apparatus carried by post e being approximately counterbalanced by a weight in a cover i. Movements of the post, carriage and beam may be effected by endless bands w attached to the part to be moved, each driven by an hydraulic-motor v. Answer-signals in response to reference-signals from the record are provided by coarse and fine adjustment potentiometers q, s rotated by a further endless-band t attached to the moving part, potentiometer q being driven through stepdown gearing r. The arms b may assist each other in picking up components, and one may replace the work-gripper of the other with another from a rack z. The apparatus may assemble apparatus similar to itself, the speed of the record-motor controlling the rate of assembly. An operation-counter is included in the control-system of the apparatus to record the order of assembling the components. When the article being assembled is supported in a universal vice, the apparatus may adjust the setting of the universal pivot of the vice. Programming. Information-signals, received from the potentiometers fed with reference. signals during manipulation of the various parts of the apparatus by hand or otherwise, and the reference-signals, are recorded simultaneously on a magnetic tape or on a disc. Photo-electric cells may be used, and different recording- channels are preferably used for each servomechanism. Alternatively, the reference-signals are pre-recorded and the recording used as the signal source. Instead of programming from the apparatus, a duplicate apparatus may be used. The first Provisional Specification describes also that the motors at the pivotal connections, which may be reversible electric motors, may also act as transducers; that gears may be included in the arm, and the gripper operated by a cable. The second Provisional Specification describes also that the servo-valves may be controlled by hand during programming to effect powermovement of the arm, and that the gripper may be a vacuum-operated device, or comprise two or three jaws operated by a scroll-cam, or be replaced by a pneumatic tool, e.g. a riveting hammer.