US3010663A - Apparatus for controlling roller mills - Google Patents

Apparatus for controlling roller mills Download PDF

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Publication number
US3010663A
US3010663A US561873A US56187356A US3010663A US 3010663 A US3010663 A US 3010663A US 561873 A US561873 A US 561873A US 56187356 A US56187356 A US 56187356A US 3010663 A US3010663 A US 3010663A
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Prior art keywords
rollers
fluid
valve
relay
pressure
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Expired - Lifetime
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US561873A
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English (en)
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Bosshard Ernst
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Buehler AG
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Buehler AG
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
    • B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
    • B02C4/00—Crushing or disintegrating by roller mills
    • B02C4/28—Details
    • B02C4/32—Adjusting, applying pressure to, or controlling the distance between, milling members
    • B02C4/36—Adjusting, applying pressure to, or controlling the distance between, milling members in mills specially adapted for paste-like materials

Definitions

  • rollers in roller mills are usually protected against undue stresses by the provision of resilient elements in the bearing stressing devices that yield under undesirably high pressures occurring when foreign bodies pass between the rollers and permit their passage therebetween.
  • a disadvantage of such known systems resides in that the rollers, urged by the resilient elements, return rather vehemently into their original position against each other or against any limiting stops provided for this purpose, after the foreign body or bodies have passed therebetween. Considerable damages may occur due to such violent return of the rollers, and the overstresses may even be so high, especially it hard or large foreign bodies pass between the rollers, that permanent impressions may remain therein.
  • the present invention provides a method for the electrohydraulic or electropneumatic control of roller mills, and considers automatic release of movably mounted rollers in case of undesirably high pressures, for example, if a foreign body passes between the rollers, and also a gradual return of the rollers into engaging position.
  • the invention also provides an apparatus for the practice of the above method which includes a valve for reversing the flow of fluid and an electromagnet whose coil actuates said reversing valve.
  • the novel arrangement also includes a safety valve, a switch cooperating therewith, and controlling -a relay in the circuit of the coil of the aforesaid electromagnet.
  • the number of safety devices generally corresponds to the number of such bearing stressing devices, but constructions are also known wherein a single roller safety device is used for each individual movable roller.
  • the apparatus of this invention represents a substantial simplification in that it uses a single safety valve for all the bearing stressing devices of the roller mill.
  • at least one reducing valve is connected to and behind the safety valve.
  • one or more check valves are mounted in appropriate positions. 7
  • rollers may be engaged or released with a single motion.
  • the novel method and apparatus may be advantageously used in roller mills of any type, especially in connection with two rollers, such as are customary in milling industry, and alsowith three or more rollers, such as used for paint and chocolate manufacture.
  • two rollers such as are customary in milling industry
  • three or more rollers such as used for paint and chocolate manufacture.
  • one or more rollers are mounted in fixed bearings and are combined with at least one roller held in movable bearings.
  • FIG. 1 is a schematic representation of a roller mill with three rollers, embodying the novel safety device, certain components of the hydraulic mechanism having been omitted for the sake of clarity;
  • FIG. 2 shows a slight modification in the electrical wiring of the electrohydraulic control device
  • FIG. 3 is a schematic View of a further modification, comprising a plurality of safety valves
  • FIG. 4 shows schematically the hydraulic portion of the control system
  • FIG. 5 is an enlarged sectional View of the safety valve
  • FIG. 6 illustrates schematically a still further modification of the control system.
  • a source of pressure such as a pump 2 generates the pressure necessary for urging the movable rollers 1a, 1b against a stationary roller 1.
  • the hydrauhc fluid flows from pump or fluid pressure generator 2 through a conduit 3, a pressure relief valve 4, a conduit 5, a reversing valve 6, conduit 7, safety valve 8, conduit 9, the pressure reducing valves 11a, 11b for the individual cylinders, and through conduits 12a, 12b into the pressing cylinders 13a, 13b, acting as the bearing stressing devices.
  • the hydraulic fluid in excess returns to the tank 15 over the pressure relief valve 4 via a conduit 14.
  • Valve 4 is of customary design; its purpose is to limit the pressure which may be built up in pump 2 by opening line 14 to line 3 whenever the pressure built up in the pump exceeds a given value.
  • Valves 11a, 11b regulate the pressure exerted on the rollers. If a foreign body enters one of the gaps 16a, 1611 when the rollers 1, 1a, 1b are in en gagement, the overstress is transmitted over the movable bearing supports 17a, 17b and pistons 18a, 18b to the hydraulic fluid in cylinders 13a, 13b. The excessive pressure is transmitted by the hydraulic fluid from said cylinders over the lines 12a, 12b and the line 9 to the safety valve 8.
  • safety valve 8 moves the rod H which actuates a switch 21, energizing relay 29' to close switch 20 and, thereby, energize relay 22.
  • Relay 22 closes contacts 24, 26 and 28.
  • Contact 24 permits the current to flow in the coil 23 which electro-magnetioally reverses the valve 6 to permit flow of hydraulic fluid to the op pistons 18a, 18b reach the end of their strokes in cylin ders 13a, 1312.
  • the safety valve 8 reaches its releasing position, i.e., when the pressure of the fluid.
  • a contact 31 actuated by the actuating coil of an adjustable timealag relay 27' mounted in series with the time-lag relay 27, may be opened after a set time period, whereby the safety switches 32, 33 of the mill driving motor 34 and the motor 35 for pump 2, respectively, are opened to idle the entire apparatus.
  • the switches 32, 33 are actuated by relays 132, 133, respectively, in the circuit of the contact 31.
  • the second timelag relay 27' may be set so asto open the switch 31 say five seconds after the opening of switch 29 for the following reason:
  • the switch 29 When the movable rollers are released because of the passage of 'a foreign body through one of the gaps 16a, 16b, the switch 29remains closed for a certain time set in the time-lag relay 27, for example thirty seconds, and is thereupon reopened to permit engagement of the rollers. If the foreign body is still between the rollers 1-1a or 1-1b, the regulating process begins anew. In such exceptional cases of extremely large foreign bodies, or when a foreign body is jammed between the rollers, the
  • second relay 27' which is mounted with the time-lag relay 27, opens the contact 31 say five seconds after the contact 29 has been opened, and the operation of the entire system is stopped.
  • the pressure in line 9 reaches a level high enough to operate rod 19, the latter is displaced in a direction to right not only to operate switch 21 but also to expose the intake end of a line 54 which latter leads back vto tank15 and :thus permits 'return flow of fluid from line 9, over valve 3, and into 'controlfsystem, a hand-actuated switch 36 is provided to.
  • the electric control system differs from the above-described embodiment in that the contact 24 is in the line between hand-switch 36 and coil 23. .Coil 23 is under current when the rollers 1, 1a, 1b are engaged.-
  • the time-lag rel ay.27 opens the holding circuit of relay '22 byhopening contact 29. With contact 29 open, relay 22 is deenergized and contact 24 closm. contact 24 closed, thecircuit of coil 23 is closed, whereuponthe 'coil 23 brings the reversing valve 6 into a position toperrnit'the pistons 18a, 18b to move the rollers 1a, 1b into engagement with the roller 1.
  • the rollers 1a, 1b again engage the stationary roller 1.
  • the second time-lag relay 27' mounted with relay 27 after a certain time (say 5 seconds after the opening of switch :29) opens the contact 31 and interrupts the control circuit of switches 32, '33 to arrest the driving motor 34 and pump motor 35. Before these motors are stopped, the rollers were automatically released, as described above.
  • FIG. 4 four cylinders 13ad of the same number of hydraulic bearing stressing devices are represented.
  • the cylinders are supplied with hydraulic fluid by the pump 2 through the reversing valve 6, conduit 7, a single safety valve 8, the pressure reducing valves Ila-d, the check valves 37a-a', and the lines 38zz-d.
  • Check valves 37a- 37d prevent small vibrations ofthe rollers from disturbing the reducing valves Illa-11d, respectively.
  • valves 37a- 37d prevent the return flow of fluid from cylinder spaces or chmbers 3942-3907, respectively, it-is necessary to provide check valves 47a-47d which.
  • the safety device 8 shown enlarged; in FIGS, includes an auxiliary cylinderStl in communication with line 7.
  • a piston 51 in the cylinder 50 is urged toward left by a coil spring 52.
  • The. tension of spring 52 may be controlled by a screwg53.
  • piston 51 moves toward right against the force of spring 52 to expose the end of the a conduit 54 leading to the tank 15.
  • piston 51 is mechanically connected with the rod 19 which presses against the end switch 21.
  • no change in the setting of roller mills has'been made because no change in reducing value was necessaryJ 7 draulic bearing stressing devices in the form of cylinders 13rz-d with a single reducing valve 11.
  • This embodiment permits the selection of different diameters for the pistons 18a-d of the individual cylinders 13ad to control the pressing forces of the individual bearings. As shown, the diameters of cylinders 13c, 13d and of their pistons 18c, 18d are larger than those of cylinders 13a, 13b and pistons 18a, 18b.
  • the above-described safety device has proven to be absolutely satisfactory when dealing with short-lived overstresses of the rollers, for example, when the foreign bodies are nails, stones, or the like.
  • Valves 4 and 11 may be provided with suitable hand grip members for manual operation.
  • a gaseous medium may be employed to provide an electropneumatic control system. Pump 2 is then replaced by a suitable blower.
  • An apparatus for the control of roller mills having fixed and movable rollers adapted to be moved into engagement with, or away from, said fixed rollers, including a source of fluid, stressing means operatively connected with said movable rollers for applying fluid pressure thereto, conduit means for connecting said source of fluid with said stressing means, a source of tfluid pressure in said conduit, fluid reversing means for controlling the flow of fluid under pressure to said stressing means whereby to move said movable rollers into engagement with, or away from, said fixed rollers, a safety device in said conduit responsive to a predetermined maximum pressure of said fluid in said stressing means, an electric circuit including switch means operatively connected with said safety device, a relay and electromagnet in said circuit, said electromagnet being controlled by said relay and operatively connected with said fluid reversing means.
  • said safety device is a safety valve and a connection is provided between said safety valve and said source of fluid for returning the fluid from said stressing means upon a predetermined maximum pressure therein.
  • each of said stressing means includes a cylinder and a piston operatively connected with a respective one of said movable rollers, said pistons having difierent diameters.
  • a first time-lag relay is in the circuit of, and controlled by, said relay, said time-lag relay operating in such manner that said movable rollers are disengaged from said fixed rollers for a predetermined period of time in response to said predetermined maximum pressure of fluid in said stressing means.
  • a second time-lag relay is in the circuit of said relay, and operatively connected with said source of fluid pressure, said second time-lag relay operating in such manner that the flow of fluid to said stressing means is interrupted when the predetermined maximum pressure of fluid persists.
  • An apparatus for the control of roller mills having fixed and movable rollers, and a drive motor for said rollers, including at least one cylinder for each of said movable rollers, a piston in each of said cylinders operatively connected to a respective one of said movable rollers for moving said movable rollers into engagement with, or away from, said fixed rollers, a source of fluid, a fluid reversing valve, a conduit for connecting said source of fluid with said reversing valve, a fluid pressure generator in said conduit, first fluid lines between said reversing valve and each of said cylinders for moving said pistons and said movable rollers in a direction to engage said fixed rollers, second fluid lines between said reversing valve and said cylinders for moving said pistons and said movable rollers in a direction away from engagement with said fixed rollers, at least one safety valve and at least one pressure reducing valve in said first fluid lines, an electric control system including a switch responsive to a predetermined maximum fluid pressure in said safety valve,
  • check valves are provided in said first fluid lines between said pressure relief valve and said cylinders.
  • a time-lag relay is provided in said electric control system and operatively connected with said motor and said fluid pressure generator.
  • the apparatus of claim 10 further comprising a third fluid line between said safety valve and each of said cylinders and a check valve in each of said third fluid lines for permitting return flow of fluid introduced through said first lines when the pressure in the respective cylinders exceeds a given value.

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  • Engineering & Computer Science (AREA)
  • Food Science & Technology (AREA)
  • Crushing And Grinding (AREA)
  • Fluid-Pressure Circuits (AREA)
US561873A 1955-01-28 1956-01-27 Apparatus for controlling roller mills Expired - Lifetime US3010663A (en)

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CH3010663X 1955-01-28

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3208678A (en) * 1963-03-08 1965-09-28 Kennecott Copper Corp Dual-pivoting, cradle type, roll crusher
US3445070A (en) * 1963-03-19 1969-05-20 Verdier Andre L Adjustment of the rolls of grinders and other machines which include rolls
JPS4928954A (de) * 1972-07-17 1974-03-14
US5372315A (en) * 1992-08-07 1994-12-13 Kloeckner-Humboldt-Deutz Ag Method and system for the pressure treatment of granular material
US5379950A (en) * 1992-12-19 1995-01-10 Buhler Ag Method and system for controlling a layer thickness in a grinding operation
US5439179A (en) * 1992-04-07 1995-08-08 Johnson & Johnson Inc. Method and apparatus for fragmenting a block of frozen vegetable tissue

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1925881A (en) * 1931-12-30 1933-09-05 Gen Electric Motor control system
US2022135A (en) * 1930-05-16 1935-11-26 Allis Chalmers Mfg Co Crusher
US2138397A (en) * 1935-10-18 1938-11-29 Hunter James Machine Co Compression roll
US2182900A (en) * 1937-11-01 1939-12-12 Vaughn Machinery Co Rubber mill
US2610801A (en) * 1949-03-12 1952-09-16 Edmund E Edmiston Roller mill
US2791383A (en) * 1952-04-10 1957-05-07 Axel W Kjelgaard Hydraulic control for gyratory crusher

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2022135A (en) * 1930-05-16 1935-11-26 Allis Chalmers Mfg Co Crusher
US1925881A (en) * 1931-12-30 1933-09-05 Gen Electric Motor control system
US2138397A (en) * 1935-10-18 1938-11-29 Hunter James Machine Co Compression roll
US2182900A (en) * 1937-11-01 1939-12-12 Vaughn Machinery Co Rubber mill
US2610801A (en) * 1949-03-12 1952-09-16 Edmund E Edmiston Roller mill
US2791383A (en) * 1952-04-10 1957-05-07 Axel W Kjelgaard Hydraulic control for gyratory crusher

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3208678A (en) * 1963-03-08 1965-09-28 Kennecott Copper Corp Dual-pivoting, cradle type, roll crusher
US3445070A (en) * 1963-03-19 1969-05-20 Verdier Andre L Adjustment of the rolls of grinders and other machines which include rolls
JPS4928954A (de) * 1972-07-17 1974-03-14
US5439179A (en) * 1992-04-07 1995-08-08 Johnson & Johnson Inc. Method and apparatus for fragmenting a block of frozen vegetable tissue
US5372315A (en) * 1992-08-07 1994-12-13 Kloeckner-Humboldt-Deutz Ag Method and system for the pressure treatment of granular material
US5379950A (en) * 1992-12-19 1995-01-10 Buhler Ag Method and system for controlling a layer thickness in a grinding operation

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CH328827A (de) 1958-03-31

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