US 5,248,042 A · Resilient wire-wrapped, and adjustably tensioned screen drum with drum overload-preventing feedback control

Abstract

A mobile screening apparatus includes a horizontal rotary drum preferably fed by underflow from a prescreening device that is reversible endless belt of screening grizzly bars. The belt reverses for expelling oversize material caught between bars. Force needed to turn the drum is monitored, as a way of controlling drum feeding by the prescreening device, for preventing protracted over-filling of the drum. The screening drum includes an outer peripheral cage of longitudinal bars, at least some of which preferably are movably mounted. A set of wires is circumferentially wrapped about the bar cage, with sufficient flexibility to permit the wires to locally elastically flex away from the bars sufficient to pass slightly oversize material and facilitate cleaning of debris lodged in spaces among the bars and wires. Brushes help dislodge lodged debris. Slanted baffles within the cage propel the processing stream of land-clearing material such as mixed dirt, stones and roots that is being screened, towards an outlet end of the drum. Underflow from the screen is conveyed by a slewable conveyor into cone-shaped piles, possibly after fertilizer or other additives are metered into the product. The apparatus can be tended by a single operator, who may use a front-end loader or similar device for dumping raw material onto the prescreening grizzly bars. Preferably, an on-board internal combustion engine powers hydraulic motors which operate the apparatus elements. Engine exhaust can be piped into the drum for heating the material being screened.

Claims34

Dependent claims

A screening apparatus, comprising:

a screening drum including a radially outer peripheral wall provided by a circumferentially extending series of longitudinally extending bars spaced from one another circumferentially of said peripheral wall so as to define slots between respective adjacent ones of said bars;
at least two axially spaced support rings;
said bars being mounted to said support rings to provide a cage structure;
and a plurality of resilient wire means wrapped circumferentially about said peripheral wall;
said wire means being provided as a series of longitudinally spaced turns, defining slots between respective adjacent ones of said turns, superimposed upon said slots between said bars and thereby cooperatively defining with said bars screening openings through said peripheral wall;
and means adjustably tensioning said wire means onto said cage structure such as to permit lumps of material while being screened within said drum, when flung through said slots between said bars so as to impact a turn of said wire means, can cause said turn to elastically flex outwardly from said cage sufficiently to temporarily locally increase the effective size of some of said openings, for thereby freeing material clogged into such openings and temporarily permitting passage through such openings of lumps of material which are normally slightly too large to pass therethrough;
inlet opening means at one end of said drum for introducing into an internal cavity bounded by said peripheral wall material to be screened;
and outlet opening means at an opposite end of said drum for evacuating an overflow fraction of said material from said drum;
a base;
means for supporting said screening drum so as to extend generally horizontally on said base;
and
means for rotating said drum relative to said base about the longitudinal axis of said drum.

9 more elements

A screening apparatus, comprising:

a screening drum including a radially outer peripheral wall having means defining openings therethrough, so that material, while being screened within said drum may pass radially outwards, out of said screening drum through said openings, providing said material is substantially of a given size or smaller;
inlet opening means at one end of said drum for introducing into an internal cavity bounded by said peripheral wall of material to be screened;
and outlet opening means at an opposite end of said drum for evacuating an overflow fraction of said material from said drum;
a base;
means for supporting said screening drum so as to extend generally horizontally on said base;
means for rotating said drum relative to said base about the longitudinal axis of said drum;
a feeding conveyor supported on said base and having a carrying run with an outlet end arranged to deliver to said internal cavity of said drum through said inlet opening means a stream of material which is to be screened;
means for driving said feeding conveyor;
control means operatively connected with said means for rotating said drum and with said means for driving said feeding conveyor, for temporarily diminishing delivery to said internal cavity of said drum, of material to be screened, at times when resistance to turning of said drum indicates said drum is already loaded with an excess of material to be screened;
and
said means for rotating said drum including an hydraulic motor incorporated in an hydraulic system and said control means including means for sensing pressure in said hydraulic system as an indication of resistance to turning of said hydraulic motor.

8 more elements

A screening apparatus, comprising:

a screening drum including a radially outer peripheral wall having means defining openings therethrough, so that material, while being screened within said drum may pass radially outwards, out of said screening drum through said openings, providing said material is substantially of a given size or smaller, said radially outer peripheral wall being provided by a circumferentially extending series of longitudinally extending bars spaced from one another circumferentially of said peripheral wall so as to define slots between respective adjacent ones of said bars;
at least two axially spaced support rings said bars being mounted to said support rings to provide a cage structure;
and a plurality of resilient wire means wrapped circumferentially about said peripheral wall;
said wire means being provided as a series of longitudinally spaced turns, defining slots between respective adjacent ones of said turns, superimposed upon said slots between said bars and thereby cooperatively defining with said bars screening openings through said peripheral wall;
and means adjustably tensioning said wire means onto said cage structure such as to permit lumps of material while being screened within said drum, when flung through said slots between said bars so as to impact a turn of said wire means, can cause said turn to elastically flex outwardly from said cage sufficiently to temporarily locally increase the effective size of some of said openings, for thereby freeing material clogged into such openings and temporarily permitting passage through such openings of lumps of material which are normally slightly too large to pass therethrough;
inlet opening means at one end of said drum for introducing into an internal cavity bounded by said peripheral wall material to be screened;
and outlet opening means at an opposite end of said drum for evacuating an overflow fraction of said material from said drum;
a base;
means for supporting said screening drum so as to extend generally horizontally on said base;
means for rotating said drum relative to said base about the longitudinal axis of said drum;
said means for rotating said drum including an hydraulic motor incorporated in an hydraulic system;
said hydraulic system includes pump means for pressurizing hydraulic fluid in said hydraulic system for turning said hydraulic motor;
and
said apparatus further comprising an internal combustion engine operatively connected with said pump means for operating said pump means;
said engine including a hot exhaust gas outlet pipe including means for diverting hot exhaust gases therefrom into said internal cavity for heating therein material to be screened.

12 more elements

A screening drum for a screening apparatus, said screening drum comprising:

a radially outer peripheral wall provided by a circumferentially extending series of longitudinally extending bars spaced from one another circumferentially of said peripheral wall so as to define slots between respective adjacent ones of said bars;
at least two axially spaced support rings;
said bars being mounted to said support rings to provide a cage structure;
and a plurality of resilient wire means wrapped circumferentially about said peripheral wall;
said wire means being provided as a series of longitudinally spaced turns, defining slots between respective adjacent ones of said turns, superimposed upon said slots between said bars and thereby cooperatively defining with said bars screening openings through said peripheral wall;
and means adjustably tensioning said wire means onto said cage structure such as to permit lumps of material while being screened within said drum, when flung through said slots between said bars so as to impact a turn of said wire means, can cause said turn to elastically flex outwardly from said cage sufficiently to temporarily locally increase the effective size of some of said openings, for thereby freeing material clogged into such openings and temporarily permitting passage through such openings of lumps of material which are normally slightly too large to pass therethrough;
inlet opening means at one end of said drum for introducing into an internal cavity bounded by said peripheral wall material to be screened;
and outlet opening means at an opposite end of said drum for evacuating an overflow fraction of said material from said drum.

5 more elements

Dependencies are inferred from the claim text.

Resilient wire-wrapped, and adjustably tensioned screen drum with drum overload-preventing feedback control

Life of this patent

Resilient wire-wrapped, and adjustably tensioned screen drum with drum overload-preventing feedback control

Life of this patent

Abstract

Claims34