Patent GB-790513-A (GB)
Title: Improvements in or relating to automatic single station balancing machine
IPC: G01M1/30
Filed: 1955-09-16
Abstract: 790,513. Rotary balancing machines. GISHOLT MACHINE CO. Sept. 16, 1955 [June 13, 1955], No. 26555/55. Class 106 (2). [Also in Groups XXII, XXXVIII and XL (b)] An automatic rotary unbalance measuring and correcting system comprises means for loading successive workpieces from a conveyer on to the measuring apparatus, means for determining the unbalance magnitude and angular position, means for causing a vertical drill to remove a predetermined quantity of material from the workpiece to neutralize the unbalance, and remeasuring the unbalance to ensure that it is within the required tolerance limits before the workpiece is loaded on to an outgoing conveyer. Balance measuring apparatus.-A vertical spindle 6 (Fig. 4) carrying a work gripper 7 at its upper end is mounted on a cradle 8 which is suspended by strips 9 from a frame 10. The spindle 6 is driven via a belt 11 by a motor 15 through a clutch and brake mechanism 14. A workpiece 19 is located on the gripper 7, and any rotary unbalance produces lateral movement of the cradle 8 which is transmitted via a rod 16 to a coil 17 located in the air gap of a magnet 18. The unbalance signals produced in coil 17 are amplified at 20 (Fig. 23) and fed through network 21 to a lamp 23 located at the bottom end of spindle 6, whereby the lamp flashes at a predetermined point in the rotation cycle to send a beam of light through a slot 25 in a cylindrical cup 24 surrounding the lamp. A photo-cell 27 mounted on a carriage 28 in a further slotted shield is rotated by a motor 29 until the two slots are in line, whereupon the signal from the photo-cell stops the motor 29 with the carriage 28 at a position indicative of the angular location of the unbalance in the workpiece. The magnitude of the rotary unbalance is determined by the deflection of the pointer 132 of a meter relay 22. When this pointer touches tolerance limit contact 134 a motor 36 is energized which rotates the slider of potentiometer 35 to produce a voltage opposing the measured unbalance voltage and simultaneously positions a cam to determine the depth of the drilling operation. The cam is designed in accordance with the weight of the material of the workpiece 19, the diameter of the drill used, the shape of its point, &c. Cycle of operations.-Initiation of the cycle is effected by a start button switch which causes the various feed motors to run continuously, and energizes a relay control circuit to produce the following sequence of events: (1) the brake and clutch mechanism 92 (Fig. 1) for loader motor 91 is energized, whereby a workpiece 19 is lifted from conveyer 3 by arms 80, and moved to the gripper 7 by pusher 78, the mechanism then returning to initial conditions with clutch 92 deenergized. (2) Clutch mechanism 14 is energized to drive spindle 6 from motor 15, whereby unbalance in the workpiece 19 produces vibration of the cradle 8 and coil 17, and an unbalance signal is developed in coil 17 which is amplified at 20 and rectified at 130 to be fed to a meter relay 22. Movement of the pointer from its zero position resting on contact 133 releases relay 135 and energizes the measuring circuit. (3) If the measured unbalance is not sufficient to cause pointer 132 to touch limit contact 134, relay 136 remains energized, and after a predetermined time delay, clutch 14 releases spindle 6 and clutch 92 is energized to cause the loading mechanism to remove the workpiece 19 from gripper 7 and place it on outgoing conveyer 4, while the next workpiece is carried from conveyer 3 on to the gripper 7. (4) If the measured unbalance is sufficient to cause pointer 132 to contact the tolerance limit contact 134, relay 136 is de-energized, motor 36 starts and rotates the slider of potentiometer 35 to produce a voltage opposing the unbalance voltage until pointer 132 returns to its zero position. The rotation of motor 36, which is a measure of the amount of rotary unbalance, is repeated by selsyn transmitter 37 and a receiver which positions a cam determining the depth of the drilling operation. When pointer 132 is again in the zero position relay 135 is de-energized, causing motor 36 to stop. The amplified unbalance signal output of coil 17 is also amplified and shaped at 20, and gives a phase displacement at 21 before triggering stroboscope light 23 to cause motor 15 to rotate the workpiece to the correct angular position relative to the drill. The drill is carried by a vertical shaft and driven by a motor mounted on the main frame, and is driven forward by an hydraulic power system to a depth determined by the setting of the cam, and then retracted. If the unbalance is very large the motor 36 is stopped by a limit switch at the end of the travel of the slider of potentiometer 35, and the balance is removed in more than one attempt. The first removal is made off-phase by energization of relay 182 producing a predetermined additional phase shift in the triggering of stroboscope lamp 23. Following retraction of the drill, the measuring cycle is restarted, and if the unbalance is now within the desired tolerance the workpiece is placed on the outgoing conveyer 4.