Patent GB-191518017-A (GB)
Title: Improvements in the Driving and Control Mechanism of Planing and like Machines.
IPC: B23D7/00
Filed: 1915-12-24
Abstract: 18,017. Igranic Electric Co., [Cutler-Hammer Manufacturing Co.]. Dec. 24. Systems for controlling reciprocating motion; controllers, actuating - mechanism for, and interlocking- devices with auxiliary switches.- An electric motor for driving' a planing- machine has series, shunt, and commutating field windings, and the circuits include a pair of rheostats selectively controlled by reversing-switches for each direction of rotation. Tappets 105, 106, Fig. 5, on the machine operate through links to rotate the master shaft 14 of the switch apparatus. Handwheels 109, 110 are connected to shafts of the field rheostats 76, 77 for the cutting and return strokes respectively. The two reversing- switches 1, 2, Fig. 1, carry the arms of auxiliary switches 8, 9, which are moved to the ' on ' position when the corresponding reversing-switch closes. Accelerating-switches 3, 4, 5 and a shunt-field weakening switch 6 are operated from the shaft 41, and an mterlocking-switch 10 is associated with the starting-button 113 so that, after a failure of voltage, all parts must be returned to their initial positions before the motor can be restarted. The arms of the reversing-switches 1, 2 are fixed to independent rectangular shafts 21, 22, to which are attached arms 25, 26 with rollers 27 working in the grooves of a cam 28 on the master shaft 14, so that the switches are closed upon reverse rotations of the shaft 14, while both are open in the central position of the shaft. The movable contacts of the accelerating-switches 3, 4, 5 are carried by arms pivoted to brackets and bearing fibre rollers 39 engaged by cams 40 on the shaft 41 so that the switches close successively. A weighted arm 43 is secured to the shaft 41 and is connected by links 47, 44, 45 to the shaft 14. The links 44, 45 form a toggle which is straight in the zero position, and which is broken by rotation of the master shaft 14 to permit the weighted arm 43 to drop to close the switches 3, 4, 5 against the restraining influence of the dash-pot 49. The fieldweakening switch 6 is opened after closure of the accelerating-switches, by a lug 60 on the shaft 41, the lug being provided with an adjusting screw. A second field switch 7 is operated by a cam 70 on the master shaft in such a manner that it is open in the central position of the shaft and closed in all other positions. The switch movement is retarded by a dash-pot so that the shaft may be moved from forward to reverse without opening the switch, and the closure of the switch ensures a strong field at starting. The motor M, Fig. 6, has a series field winding f, a shunt winding f<3>, and interpole and commutating windings f<1>, f<2>. To start the motor, the button 113 is depressed to close the main switch 114. Current then flows through the shunt winding f<3 >and the rheostats 76, 77. The master shaft is then rotated by movement of the handle 107. This closes the reversing-switch 2 for the cutting stroke, closes auxiliary switch 9, opens switch 7, and then closes the accelerating-switches 3, 4 to cut out resistance r, r<1>, and closes switch 5 to short circuit the commutating-winding f<2>. The switch 6 is then opened to include the field rheostat 76, the other rheostat 77 being short circuited by the switch 9. At the end of the stroke, the shaft 14 is operated to close the reversing- switch 1 for the return stroke, and a similar action occurs, except that the resistance r only is included in the armature circuit and the field rheostat 77 is included instead of the rheostat 76. The two field rheostats are adjusted for different speeds. The motor is stopped by the operator moving the handle 107 to bring the shaft to its central position. If the switch 114 breaks the power supply, a dynamic braking circuit is closed through the resistance r<3> and through the reversing- switch which happens to be closed at the time.