Patent GB-792983-A (GB)
Title: Improvements in apparatus for predetermining quantities of sand and water to be mixed according to a quality of the sand
Inventor: HARTLEY NELSON
IPC: B22C5/08
Filed: 1954-08-20
Abstract: 792.983. Mixing apparatus. HAYLCO CONTROLS CORPORATION. Aug. 20, 1954, No. 24352/54. Class 86 Apparatus for predetermining quantities of sand and water to be mixed, according to the quality of the sand, namely, its temperature and/or its moisture content, comprises a first measuring instrument exposed to stand and responsive to said quality, a second water quantity measuring instrument exposed to the water, an integrating instrument assowith the first and second measuring instruments for actuating the valve to control the delivery therethrough of an amount of water dependent upon the sand quality. In the construction shown in Fig. 1 a foundry sand mixer 10 is provided with a water inlet at 12 and a sand-receiving hopper 13. Previously - used foundry sand with additional sand to make up losses is stored in a bin 14 provided with inter-geared discharge valves 15 operated by the piston rod 17 of a cylinder 16. The sand is discharged into a measuring hopper 18 provided with intergeared discharge valves 19 operated by the piston rod 20 of a cylinder 21. The cylinders are supplied with air from a supply line 25 under the control of a manually-operated rotary valve 27. Water required for addition to the sand in the hopper 18 is accumulated in a tank 30 from a water supply line 31 controlled by an electromagnetically-operated valve 32. A float 33 in the tank communicates motion by rack and pinion 34, 35 through gears 36, 37 and flexible shaft 38 to an intergrating device which determines the amount of water flowing into tank 30 to provide a primary amount independent of sand temperature and a secondary amount proportional to sand temperature. This temperature is obtained by a thermometer 50 in the hopper 18, the thermometer communicating through an armoured tube 52 with a Bourdon tube 53 in a case 54, Figs 4, 5, and 6. The tube 53 has an arm 55 connected by link 56 with a composite lever comprising parts 57, 58 pivoted on a pintle 59 and adjustably connected by a bolt 60 The lever carries a gear segment 63 meshing with a pinion 64 on a quill shaft 65 carrying a pointer 66. The pointer operates over a dial 67 indicating temperature. A shaft 96 which extends through the quill shaft 65 and carries a pointer 98, has a pinion 95 meshing with the gear segment 94 carried by a lever 88 which is pivoted on a pintle 59 and supports a switch 90. The contacts of switch 90 are normally closed and are opened when a finger 70 carried by lever 57, 58 engages an actuator on the switch. This happens when the pointer 66 registers with pointer 98. The rotation of shaft 38 by the float of the water-measuring tank drives a worm 73 and worm gear 74 mounted on a shaft 75 which is provided with a knob 76 and a pointer 77 movable over a dial 78 indicating volume. The shaft 75 is rotatably and slidably mounted, being spring pressed rearwardly, and carries a pinion 82 meshing with a gear 83. This gear has an arm 84 which has a pin and slot connection with a link 85 connected to the lever 88. To operate the device the operator pulls out the knob 76 to disengage the worm 73 from the worm gear 74 and sets the pointer to indicate the amount of liquid which the sand requires regardless of temperature The knob is then released and the valve 27 is put in to the position shown in Fig. 1. whereby air pressure opens valves 15 and closes valves 19, allowing sand to pass from bin 14 to hopper 18. Air pressure also operates a pressure, switch.. 115 to close a circuit through the filament 119 of an electronic tube 120. The heating of the filament requires time which allows the thermometer 50 to reach the temperature of the sand admitted to the hopper 18. The temperature effects movement of the pointer 66. When the filament heats up current flows between plate elements 122. 124, energizing a relay coil 109 to close a circuit through the coil 110 of electromag- .netic valve 32 whereby the valve opens and water flows into the measuring tank 30. The float 33 through the flexible shaft 38 causes the pointer 77, Fig. 4, to move back towards zero. During this time pin 86 has been moving idly in slot 87 in the link 85. When the pointer reaches zero. indicating that all the primary amount of water has been delivered to tank 30, the pin 86 actuates the link 85 upwardly to tilt lever 88 and move switch 90, the pointer 98 moving over its dial. When it registers with pointer 66 the finger 70 engages a switch actuator so that the switch 90 is opened and the valve 32 closes to cut off further supply of water. The tank 30 has now in addition to the primary amount a secondary amount corresponding to the sand temperature. Air control valve 27, Fig. 1, is then operated to release the sand to the mixer 10 and at the same time allow air pressure through a pipe 47 and a cylinder 40 to lift a valve and allow liquid to flow from the tank 30 to the mixer. In an alterative construction the amount of primary moisture to be added to the sand instead of being determined by manual presetting is determined automatically. Electrodes 130, 131, Fig. 15, spaced apart in the measuring hopper are connected in an electric circuit the electrical resistance of the sand between the electrodes being an index of its dryness. The secondary of transformer 133 is connected by lead 134 to one electrode 130 and by lead 141 through rectifier 135 and relay coils 136, 139 in series to the other electrode 131. The coils are similar but attract the respective armatures 140...143 at successively higher current flow. When armature 140 is attracted a circuit is closed through a coil 147 to actuate a solenoid armature 150 and raise a lever 175. When the flow of current through electrodes 130, 131 increases armature 141 is attracted by coil 137 causing relay coil 153 to be energized and the lever 175 to be raised again. Also a switch 157 is closed to short circuit the relay coil 136. -Similarly energization of coil 138 by a still higher flow of current causes short-circuiting of relay coil 137 and the raising of lever 175. At the same time an arm 165 carried by armature 162 closes a switch 168 to provide a holding circuit for relay coil 161 when coil 138 is energized. The fourth relay coil 139 is provided to give warning by light 171, of a fault such as a short-circuit. The lever 175 is pivoted on a pintle 182, Fig. 11, and at its shorter end is adjustably connected to a link 185 which is connected by a pivot bolt 186 to lever 841 pivoted to the gear 83. The lever 841 is adjustably connected to a link 851 connected to the lever 88 carrying switch 90. The rising of the float in the measuring tank will transmit movement to the lever 88, the datum position of which is varied by the tilting of the lever 175. In a modification the water instead of being measured after it arrives in the tank 30, Fig. 1. is measured as it enters the tank by passing it through a meter the pointer shaft of which is connected to the flexible shaft 38 leading to the integrating device.