Patent GB-509713-A (GB)
Title: Improvements in tea rolling machines
IPC: A23F3/12
Filed: 1938-01-19
Abstract: 509,713. Tea-rolling machines ; control of motors. COLOMBO COMMERCIAL CO., Ltd., SALMON, R. M., WILTSHIRE, G. R., and LAWTON, C. R. Jan. 19, 1938, No. 1849. [Class 129] [Also in Group XXXVII] The pressure plate c of a tearolling machine is driven to upper and lower positions under the control of terminal limit devices of which the lower terminal limit device is operated by the reaction pressure of the tea leaf to stop the downward drive when a given pressure is reached, the device being adjustable to vary such pressure. The total rolling period includes a series of pressure periods and release periods and an automatic control arrangement provides for this, all the periods being adjustable to requirements. The downward movement of the pressure plate c is effected by a sleeve shaft e which is rotated by a motor k or by a hand wheel d through a bevel-gear drive and has an internally screw-threaded end e<5> engaging a screw spindle f on the pressure plate, the plate being restrained from rotation. When the reaction pressure of the tea leaf on the plate overcomes that imposed by a spring,j, the continued rotation of the sleeve shaft e results in its rising on the screw spindle f and thereby a collar e<4> on the sleeve shaft operates a rod e<3> to open a contact l. Adjustment of the pressure is effected by appropriate screwadjustment of a ring e<2> on the collar, the setting being shown by an indicator m. The upper limit contact o is opened by a rod c<2>. The automatic control arrangement is shown in Fig. 7, and includes timing devices F, E, G of a form shown in Fig. 3 in which a bar F<1> is intermittently stepped up by a magnet Z<1> provided that a magnet Z<2> is energized to attract a gripping arm Y<3>; the bar F<1> is held up by a magnet Z<3>, but drops when this Magnet is de-energized. An adjusting nut H<3> varies the time required to close contacts H, H<1>. The arrangement shown in Fig. 7 should now be considered in which a start button s has been briefly operated to operate a main switch 6 by energizing a winding 5 over a circuit +ve, wire 45, winding 5, wire 46. a, contact 41 of the total period timing device F, unoperated stopbutton v, operated start-button s, wire 48, - ve. The switch 6 moves its contact bars 7, 8 to the position shown and it will be seen that the winding 5 now remains energized by a connection to - ve from the button v, over wire 88, bar 7 and wires 49, 60, 48. The motor k drives downwardly when a motor control winding 11 is energized from +ve, over wires 45, 50, bar 8, wire 57, lower limit switch l, winding 11, wire 55, contact 54, and negative bar 7 ; the drive stops when the switch l is opened by the proper rolling pressure being reached. The intermittent energization of the timing devices F, E, G is provided by a thermal contact 15 of which the heater 14 is energized by current from positive bar 8 of the mainswitch 6 over a contact 26, wires 64, 49, 60, 48 to - ve. When the contact 15 closes, a current passes from +ve over wires 45, 50, 65, 66 to a winding 16 and magnet Z<2>E in parallel, wire 67, contact 26, wires 64, 49, 60, 48 to - ve. The winding 16 operates the contacts of a switch 18 to the lower position whereby the magnet Z<1>E is energized. The magnets Z<1>E and Z<2>E lift the timing bars E, G in common. The timing bar F is similarly lifted by magnets Z'F, Z<2>F; the magnet Z<1>F is energized after a switch 19 has been operated to the lower position by the energization of its winding 17 from the thermal contact 15 over wires 74, 75, the winding 17, wires 76, 77, contacts 24, 25 (closed when Z'E was energized), wires 78, 64, 49, 60, 48 to - ve. The magnet Z<1>F operates the contact 26 to the lower position, thereby de-energizing'the heater 14 and also the windings 16 ; the winding 17 is later de-energized. Thus, the magnets Z'E, Z<1>F become de-energized. A holding magnet Z<3>E is energized from +ve, over wire 73, upper limit contact o (closed since the pressure plate is in the bottom position), wire 72, magnet Z<3>E, wire 71, top contact of switch 18, wires 70, 60, 48, to - ve. Accordingly the timing bar E is held up ; the timing bar G, however, drops since its holding magnet Z<3>G is de-energized as the circuit is open at the open lower limit contact l. A holding magnet Z<3>F is energized from positive bar 8, over wire 58, magnet Z<3>F, wire 59, top contact of switch 19, wire 61, to negative bar 7 and accordingly the timing bar F is held up. The above action is repeated until the timing bar E has risen to close a contact 27, 29 whereupon a motor control winding 31 is energized to cause the motor k to drive upwardly, the circuit being from +ve over wire 73, contact o (closed until the upper position is reached), winding 31, wire 82, contact 29, 27, wires 80, 49, 60, 48, - ve. With the pressure plate in the upper position the magnet Z<3>E is de-energized and now the thermal contact pulses cause the timing bar G to rise since the magnet Z<3>G is energized from positive bar 8 over wire 57, lower limit contact l (closed since the pressure plate is in the upper position), wires 56, 85, magnet Z'G, top contact of switch 18, wires 70, 60, 48, to - ve. When the bar G has risen to close contact 36, 37, the motor control winding 11 is energized to cause a downward drive of the motor k, the circuit being positive bar 8, wire 57, lower limit contact l closed until the pressure plate has descended to reimpose the pressure), winding 11, wires 55, 86, contact 37, 36, wire 87, contact 40, 39, wire 47, unoperated stop-push v, wire 88, negative bar 7. Thus, the bar E controls the time of each rolling period and the bar G the time of each release period, these periods recurring in turn until the bar F has risen to open the contact 41, whereupon the main switch 6 is released and the action ceases. A warning signal is given at the termination. If the pressure falls during a rolling period, the contact l closes and the motor is driven downwardly until the pressure is restored. A battery of machines can be operated by connecting each machine in turn to the control panel and starting the apparatus.