Patent GB-767242-A (GB)
Title: Apparatus for automatically measuring, mixing, and delivering foundry sand from a storage bin to an individual molder's hopper
Inventor: HARTLEY NELSON
IPC: B22C19/04
Filed: 1954-12-02
Abstract: 767,242. Mould and core materials. RAYLCO CONTROLS CORPORATION. Dec. 2, 1954, No. 34946/54. Class 83 (1). [Also in Groups XXX, XXXV, XXXVI and XXXVIII] In a method of delivering sand from a storage bin 14 to a moulder's hopper 535, 545 when the level therein falls below a certain level, the sand is mixed with a quantity of liquid proportioned to the initial moisture and temperature of the sand. Sand is delivered from the bin 14 to a batch-measuring hopper 18 by actuating an aircylinder 20 controlling gates 16. A further cylinder 21 controls gates 19 to deliver the batch to a mixer 10. Water is delivered to the mixer from a batch-measuring tank 30. The tank is supplied by a pipe 31 under the control of a solenoid-valve 32 and filling is controlled by a float 33, a rack-and-pinion 34, 35 and a drive 38 to means described below. Dry powdered bond is also delivered down a pipe 17 to the mixer 10, from a bin 8. The amount of bond is measured in a telescopic chamber 11, the adjustable length of which determines its capacity and which is opened and closed by an air-cylinder 8 controlling a valve rock-shaft. The sand from the mixer 10 is delivered to a container 47 by operation of gates 45 by an air-cylinder 46 and conveyed by a belt 48 to the hopper 535 or 545, according to the setting of ploughs 565 operated by air-cylinders 575. The solenoid-valve 32 for filling the water-tank 30 is controlled by a switch-actuator 91, Fig. 3, of a switch 90, Figs. 2 and 3. The switch 90 is movable bodily by the rising of the float 33 through the drive 38 and a gear 83. The operator initially sets the position of the gear 83 by a knob 76 which determines the required moisture content of the mixture. The actuator 91 is operated by an arm 70 which is set in position direct from a probe 50 in the batch-hopper 18 which measures the temperature of the sand. The direct drive may be replaced by powered means in which the probe moves a contact arm 550, Fig. 16, through a Bourdon tube 530. The contact completes a circuit through contact 570 or 580 to energize a relay 660 or 661 to rotate a motor 670 in one or other direction. The motor 670 rotates gearing to move a plate 590 carrying the contacts 570, 580 until equilibrium is again established, and also rotates a selsyn motor 263. Movement of the motor 263 is copied by a selsyn motor 62 which rotates the arm 70 and also a pointer 66. Powered means may also replace the direct drive 38 from the float 33. Movement of the float is then transmitted by a selsyn motor 280, Fig. 16, to a motor 283 which rotates the gear 83 by way of the shaft carrying the knob 76. Axial movement of the knob 76 disengages the drive for setting purposes. The amount of water in the tank 30 is indicated by a pointer.98 moved by an arm 88 carrying the switch 90. When the pointers 66, 98 coincide, the water valve 32 is shut off. The moisture content of the sand in the bin 14 is measured by probes 13, 131 which pass a current through the sand between them according to the water content of the sand. They are in circuit with two relays 95, 97 which are actuated respectively by a current of 5 and of 10 milliamps. The first relay, when closed, energizes a motor 105 to rotate a rheostat 100 to reduce the current and a shaft 110 carrying cams which actuate switches 120 in turn to set a limit-switch for the motor when it is reversed, to stop the motor if the second relay has not been actuated by increased current between the probes and, if it has, to illumine a series of lamps 120a to show the operator how the water-measuring operation is progressing. Rotation of the motor 105 also rotates a gear 189 carrying a link which modifies the position of the switch 90 through linkage 185, 84, 85. The circuit of the motor 105 is conditioned by a pressure-switch 77 associated with the dump-valve 43 from the tank 30. When the valve is opened to dump the water into the mixer 10, the valve 77 closes and reverses the motor 105 to its initial position. A valve 125 in the circuit of the switch 90 ensures that operation of the valve 32 is delayed until the thermometer 50 has responded to the temperature of the sand in the batch-hopper. Delayedaction relays 201, 202, Fig. 16, are also provided in the circuit for the motor 670 so that vibrations of the arm 550 due to external mechanical causes have no effect. If slurry, instead of a powdered bond, is added to the sand, through the pipe 17, it is fed into the tank 30 by the pipe 31 from a tank 275, Fig. 29. The amount to be fed is set by a subsidiary knob or pointer on a shaft which also carries a cam to operate a switch 288 so that, in operation, a slurry-valve 291 is opened and closed before the switch 90 becomes effective to open the water-valve 32. The latter cam-shaft is geared to the gear 83 so that the switch 90 is moved during feeding of the slurry. The movement of the switch may be entirely due to the slurry addition if the sand is initially very wet. Emptying of the moulder's hopper 535 is signalled by the reduction of current passed between probes 150, 151 as the level of sand drops. The reduced current actuates a relay 160 to open a valve 153 and lower the plough 565, to energize the conveyermotor 49 and to operate a timer 170. Camoperated switches 177, 178 are also brought into a circuit to a sequence-control-motor 180 which, however, cannot be started until adequate batches of sand and water are ready. Switches 130, 141, Fig. 2, or alternatively, a relay 204, Fig. 16, are not closed to operate the intervaltimer until the measuring operations are complete. The switch 130 is operated by the rise of sand against a lever 131. The sequencecontrol cam-shaft 183 can be hand-turned, if required, by a crank applied at 179; in the latter case, a switch 168 is set in " manual " position as shown by broken lines in Fig. 2 and the machine is operated by a push-button 169. If a moulder's-hopper is not in use, a switch 164 is closed so that the plough remains up. The cams 184-189 carried by the shaft 183 operate in turn a damper 28 allowing a constantlyoperating blower 24 to exhaust the mixer of air and dust, a damper 26 allowing a similar blower 23 to blow air into the mixer; the device 11 to release powdered bond into the hopper 18; means to open the water-dump-valve 43; means to close the sand-gates 16 and open the gates 19, and means to open the gates 45 after a timedelay controlled by the timer 170. Two other cams 255, 256 operate alternately, the sequencecontroller-motor 180 and the interval-timermotor 270. If there is a demand for sand when mixing is complete, the sequence-motor 180 operates again immediately. Instead of delivering batches of sand, the machine may be designed to deliver a continuous stream of sand from a bin 1400, Fig. 30, and the mixing is effected by deflecting plates 1330 while the material is on a conveyer 1800 having side-plates 210. The thermometer 50 and probes 1300 measure the conditions at the hopper-exit continuously. Batches are measured by operating a conveyer-motor 213 for predetermined intervals by a switch 157 and dog 156. The paddle 1330 is only effective when it has been swung about a pivot by sand lying at a predetermined height on the conveyer. If the sand does not reach this height a warning device is actuated or the entire machine is shut down.