US3606954A - Control system for stacking equipment - Google Patents

Control system for stacking equipment Download PDF

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Publication number
US3606954A
US3606954A US879501A US3606954DA US3606954A US 3606954 A US3606954 A US 3606954A US 879501 A US879501 A US 879501A US 3606954D A US3606954D A US 3606954DA US 3606954 A US3606954 A US 3606954A
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United States
Prior art keywords
bed
stacker
layer
control system
conveyor
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Expired - Lifetime
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US879501A
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English (en)
Inventor
Gerald C Mayer
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hewitt Robins Inc
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Hewitt Robins Inc
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    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
    • G05D5/00—Control of dimensions of material
    • G05D5/02—Control of dimensions of material of thickness, e.g. of rolled material
    • G05D5/03—Control of dimensions of material of thickness, e.g. of rolled material characterised by the use of electric means
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65G—TRANSPORT OR STORAGE DEVICES, e.g. CONVEYORS FOR LOADING OR TIPPING, SHOP CONVEYOR SYSTEMS OR PNEUMATIC TUBE CONVEYORS
    • B65G69/00—Auxiliary measures taken, or devices used, in connection with loading or unloading
    • B65G69/10—Obtaining an average product from stored bulk material

Definitions

  • a novel bed blending system which produces uniform thickness layers in the bed.
  • a conveyor feeds a conventional traveling stacking boom which deposits material on the bed as it travels.
  • the bed is formed, layer by layer, on successive passes of the stacker.
  • the control system monitors the feed rate and controls the stacker speed to provide for controlled layer thickness in the bed as conveyor speed and mass feed vary.
  • the control system is so designed that a layer of the bed is uniform along the bed but is capable of providing variations in bed layer thickness from one layer to the next.
  • FIG. 1 is a plan view of the layout of a modern bed blending system
  • FIG. 2 is an elevation view of the system illustrated in FIG. 1;
  • FIG. 3 is a plan view of an early bed blending system
  • FIG. 4 is an elevation view of the system illustrated in FIG. 3;
  • FIG. 5 is a cross section of FIG. 4;
  • FIG. 6 illustrates the stacker conveyor
  • FIG. 7 is a schematic diagram of the control system.
  • bed blending is used for a variety of purposes. In one application, it can be used to average out raw ore taken from a mine so as to obviate the necessity for expensive and wasteful selective mining. In another type of use, a bed blending system can be used to mix a plurality of ingredients to a particular recipe in preparation for further processing. Such a recipe allows the processing plant to be operated for efi'icient processing with a minimum of maintenance and adjustment. This also allows use of highly efli cient and, if desired, automated processing plants with further savings in costs.
  • FIGS. 3, 4 and 5 reproduced from Messiter, show respectively plan, elevation and cross section views of a bed blending system.
  • the material such as iron ore, coal, cement, etc.
  • FIGS. 3, 4, and 5 show diagrammatically how the material travels down the conveyor to the tripper device a and is laid onto the pile f.
  • the continous back and forth travel of the tripper device results in a plurality of layers being formed.
  • FIG. shows that as the material is deposited, a roughly triangular pile is formed. As the pile grows, the material is deposited at the apex and falls down both sides of the pile.
  • FIGS. 1 and 2. A modern bed blending system is shown in FIGS. 1 and 2..
  • a plurality of beds 1 are shown.
  • Raw material is brought in by distributing conveyor 2.
  • the material can then be switched to one of the stacking and reclaiming conveyors 3, 4, or 5 from distributing conveyors 2, 6, or 7.
  • the illustration shows the incoming material on stacking conveyor 4.
  • Tripping trailers 8 and 9 are provided for discharging material from conveyor 4 onto the stacker conveyors 19.
  • trailer 8 is not in use and trailer 9 is operatively associated with the stacker 11.
  • the stacker is capable of feeding one or both piles directly adjacent its path. As stacker 11 moves back and forth along the bed, the material ejected forms the piles 1.
  • the reclaimer 12 is put into operation.
  • the reclaimer 12 may be of the bucket wheel type shown, for example, in Dischinger, US. Pat. 3,069,027, issued Dec. 18, 1962. As explained in that patent, the reclaimer continuously slices the pile and carries off the resulting blended product.
  • FIG. 1 illustrates reclaiming conveyor 3 carrying off the blend to collecting conveyor 13 for subsequent use.
  • control layer thickness is (a) belt loading, that is the density of material on the conveyor; (b) belt speed; and (c) stacker speed.
  • the product of belt loading and belt speed is mass flow, which, when divided by stacker speed results in density in the bed.
  • control system of the present invention solves this problem by assuring longitudinal uniformity, yet providing for variations in layer thickness between layers. In the example given above, the excess /2 layer would be spread out over the entire bed at /2 normal thickness. This will provide the proper recipe and proper blending.
  • control system readily lends itself to remote operation which, in turn, is capable of automation if desired.
  • FIG. 6 shows the stacker 11 used in the present invention.
  • the stacker 11 travels on rails 14.
  • a conventional frame 15 supports the operating elements on wheels 16.
  • each wheel 16 is driven by a separate AC. motor, however, only one motor 16 is shown in FIG. 7 for the sake of clarity.
  • the stacker trailer 9 supports a conveyor 4 so as to discharge ontostacker conveyors 19 mounted on boom arms 20.
  • Boom arms 20 may be raised or lowered by conventional cable haulage systems 21 so as to clear the top of the bed as the bed increases in height.
  • conventional stackers can often have only one arm which pivots about a vertical axis so as to serve beds on either side of the stacker.
  • an automatic stacker can be made in the form shown in FIGS.
  • FIG. 7 shows the control system of the present invention.
  • the nuclear scale 22 comprises sensing heads 32 and 33. Power is supplied by supply 31 and the signal from sensing head 33- is amplified and linearized by amplifier 23. Sensing heads 32 and 33 are positioned so that the material on stacker conveyor 19 is measured. The output of scale amplifier 23 is connected to one input of analog multiplier 24. Tachometer 30 is mechanically coupled to stacker conveyor 19 and senses the speed thereof. The tachometer 30 produces an electrical analog signal proportional to the speed of the conveyor 19. This signal provides the second input to analog multiplier 24. The output of analog multiplier 24 is fed to potentiometer 25. Wiper 34 of potentiometer 25 picks off a selected portion of the signal fed to the potentiometer by the multiplier 24.
  • the signal picked off by Wiper 34 is fed as one input to the error amplifier 26.
  • Tachometer 29 is mechanically coupled to one of the stacker driving motors 28. This tachometer provides an output signal proportional to the speed of the stacker 11.
  • the signal from tachometer 29 provides the other input to error amplifier 26.
  • Amplifier 26 comprises the two input signals and the output is proportional to the difference of these signals.
  • the output of error amplifier 26 is fed to variable frequency control 27. This converts the error signal into a suitable form for controlling the stacker drive motors 28.
  • One suitable form of variable frequency control 28 is commercially available from Ramsey Controls, Inc., Mahwah, NJ.
  • FIG. 7 illustrates only one motorwheel combination, it should be understood that the stacker 11 is normally provided with at least four or more driving wheels. Usually each driving wheel is associated with a separate motor, so generally four motorwheel combinations will be present.
  • the stacker conveyor 19, operatively associated with the stacker trailer 9 delivers material to the bed.
  • the material passes between sensing heads 3233- of the nuclear scale 22.
  • the scale relies on the reduction in transmission of radiation between sensors 32-33 to indicate the mass or weight of material.
  • Power supply 31 and amplifier and linearizer 23- provide a signal proportional to the mass or weight of material on the belt. This signal may be quantized in terms of pounds per feet.
  • Analog multiplier 24 multiplies this by the conveyor speed signal from tachometer 30.
  • the output of multiplier 24 is a signal proportional to mass flow which can be expressed as pounds per minute.
  • the output from multiplier 24 is then applied to potentiometer 25.
  • the potentiometer 25 is calibrated in terms of bed layer thickness as a reciprocal function of its resistance. That is, maximum layer thickness corresponds to minimum resistance or the lower end of the potentiometer as shown in FIG. 7. With the wiper 34 at the midpoint, the result would be a layer twice as thick as if the wipe
  • the control system operates as follows.
  • the nuclear scale output indicates the belt loading factor.
  • Tachometer 30 indicates belt speed.
  • the output of analog multiplier 24 is proportional to mass flow which can be expressed in pounds per minute.
  • the setting of potentiometer 25 corresponds to a preselected layer thickness. This selected portion of the output of multiplier 24 is compared with a signal proportional to the speed of the stacker 11 as developed by tachometer 29. The comparison is effected by error amplifier '26 in a conventional manner. Variations in the amplitude of either or both inputs will vary the amplitude of the output of error amplifier 26. In order to provide for direct motor control, this amplitude signal is converted into a variable frequency signal by variable frequency control 27.
  • variable frequency control 27 consists of a signal whose frequency is related to the output of error amplifier 26. This variable frequency signal is suitable to control motors 28. This mode of operation will cause the stacker speed to compensate for changes in mass flow so as to maintain constant layer thickness. However, as explained above, it is sometimes desirable to vary layer thickness from one layer to the next. For instance, assume it is desired to provide a layer of /2 normal thickness. If normal thickness corresponds to the lower quarter point of the potentiometer, that is the 25% point, a layer of half this thickness can be provided by raising the potentiometer to the 50% point. In effect, this will double the voltage delivered by the potentiometer to the comparison circuit.
  • the stacker speed In order to drive the error voltage to zero, which corresponds to the output of amplifier 26, the stacker speed will have to double. With other factors being equal, this doubling of stacker speed will produce a layer which is /2 the thickness of the standard layer. Of course, if either of the other factors vary the control system will compensate for such variation by adjusting stacker speed to nullify the effect of any such unwanted variation.
  • Potentiometer 25 then presents the operator with a readilly controlled parameter which renders control of layer thickness a simple matter. Inasmuch as the only connections between the control system and the blending system itself are electrical, this is readily adaptable to remote operation. Automation can also be provided for simply. A program can be written out in advance specifying which materials are to be delivered on particular passes of the stacker. A counter would then control the supply of material to conform to the program. If layer thickness were desired to vary, relays could be used to pick the proper layer thickness off of potentiometer 25 in response to the program and the count stored in the counters. Such a system would completely eliminate the operators.
  • the present system provides for remote operation of of the bed blending system. With one setting, choosing predetermined layer thicknes, the operator sets in motion the system. Variations in mass flow, which are unavoidable are automatically compensated for by the system by varying the stacker speed. The layer thickness then is unvarying longitudinally which is the sine qua non of the bed blending system.
  • the control system also provides for readily variable layer thickness if necessary or desirable when blending to a particular recipe.
  • a bed blending system including a conveyor system for feeding material to a stacker
  • a control system for controlling the speed of said stacker comprising,
  • said means to determine the rate of flow of material from said stacker comprises a nuclear scale mounted on said stacker producing a first electrical signal proportional to the mass of material passing a point on said stacker,
  • multiplier means for multiplying said first two electrical signals to produce a third electrical signal proportional to said rate of material flow from said stacker.
  • said means comprises a potentiometer across which said third electrical signal is produced, said potentiometer being calibrated in terms of layer thickness, the wiper of said potentiometer feeding a selected portion of said third electrical signal to said difference amplifier, the selected portion being in inverse proportion to said selected layer thickness.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Automation & Control Theory (AREA)
  • Mechanical Engineering (AREA)
  • Control Of Conveyors (AREA)
US879501A 1969-11-24 1969-11-24 Control system for stacking equipment Expired - Lifetime US3606954A (en)

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US87950169A 1969-11-24 1969-11-24

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US (1) US3606954A (enrdf_load_stackoverflow)
JP (1) JPS5014022B1 (enrdf_load_stackoverflow)
CA (1) CA922260A (enrdf_load_stackoverflow)
DE (1) DE2057394A1 (enrdf_load_stackoverflow)
FR (1) FR2068617B1 (enrdf_load_stackoverflow)
NL (1) NL7017047A (enrdf_load_stackoverflow)
ZA (1) ZA707726B (enrdf_load_stackoverflow)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3782528A (en) * 1970-09-14 1974-01-01 Koninklijke Hoogovens En Staal Method and a device for mixing and homogenizing of bulk material
US4052800A (en) * 1974-08-01 1977-10-11 Salzgitter Ag System for gathering solids from the ocean floor and bringing them to the surface
US5959870A (en) * 1998-02-20 1999-09-28 Gamma-Metrics Real-time optimization for mix beds
US20180339871A1 (en) * 2017-05-23 2018-11-29 Northwestern University Devices for and Methods of Forming Segregated Layers from Mixtures of Granular Materials

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2189296B1 (enrdf_load_stackoverflow) * 1972-06-23 1975-03-07 Lafarge Sa
JPS5214531U (enrdf_load_stackoverflow) * 1975-07-18 1977-02-01
FR2440329A1 (fr) * 1978-11-03 1980-05-30 Fives Cail Babcock Procede de stockage de produits en vrac sur un parc de prehomogeneisation circulaire, et installation pour la mise en oeuvre de ce procede
HU209569B (en) * 1987-04-02 1994-07-28 Bodi Method of industrial homogenization for bulk, preferably granular, clumpy, solid material
DE4114903A1 (de) * 1991-05-07 1992-11-12 Krupp Polysius Ag Vorrichtung zum abraeumen einer schuettguthalde
CN102807084B (zh) * 2012-09-18 2015-04-29 永城煤电控股集团有限公司 一种筛末煤质量控制装置及方法

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR79145E (fr) * 1961-01-13 1962-10-26 Mines De Fer De La Mouriere So Procédé et installation pour assurer l'homogénéisation d'un produit divisé unique, de qualité irrégulière, ou l'homogénéisation d'un mélange de deux ou plusieurs produits divisés introduits en proportions définies
US3139217A (en) * 1961-07-31 1964-06-30 Trans Weigh Company Automatic control of the flow of bulk materials on conveyors
BE654220A (enrdf_load_stackoverflow) * 1963-10-10 1965-02-01
FR1411284A (fr) * 1964-08-24 1965-09-17 Ohmart Corp Procédé et appareil pour peser d'une manière continue de la matière se trouvant sur un transporteur

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3782528A (en) * 1970-09-14 1974-01-01 Koninklijke Hoogovens En Staal Method and a device for mixing and homogenizing of bulk material
US4052800A (en) * 1974-08-01 1977-10-11 Salzgitter Ag System for gathering solids from the ocean floor and bringing them to the surface
US5959870A (en) * 1998-02-20 1999-09-28 Gamma-Metrics Real-time optimization for mix beds
AU723878B2 (en) * 1998-02-20 2000-09-07 Gamma-Metrics Real-time optimization for mix beds
AU723878C (en) * 1998-02-20 2004-04-29 Gamma-Metrics Real-time optimization for mix beds
US20180339871A1 (en) * 2017-05-23 2018-11-29 Northwestern University Devices for and Methods of Forming Segregated Layers from Mixtures of Granular Materials
US10926966B2 (en) * 2017-05-23 2021-02-23 Northwestern University Devices for and methods of forming segregated layers from mixtures of granular materials
US12275605B2 (en) 2017-05-23 2025-04-15 Northwestern University Devices for and methods of forming segregated layers from mixtures of granular materials

Also Published As

Publication number Publication date
DE2057394A1 (de) 1971-05-27
CA922260A (en) 1973-03-06
FR2068617B1 (enrdf_load_stackoverflow) 1974-09-20
FR2068617A1 (enrdf_load_stackoverflow) 1971-08-27
JPS5014022B1 (enrdf_load_stackoverflow) 1975-05-24
NL7017047A (enrdf_load_stackoverflow) 1971-05-26
ZA707726B (en) 1971-09-29

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