CA1168181A - Grain lifting and discharge apparatus - Google Patents
Grain lifting and discharge apparatusInfo
- Publication number
- CA1168181A CA1168181A CA000381700A CA381700A CA1168181A CA 1168181 A CA1168181 A CA 1168181A CA 000381700 A CA000381700 A CA 000381700A CA 381700 A CA381700 A CA 381700A CA 1168181 A CA1168181 A CA 1168181A
- Authority
- CA
- Canada
- Prior art keywords
- grain
- belt
- buckets
- inches
- speed
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- 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
- B65G17/00—Conveyors having an endless traction element, e.g. a chain, transmitting movement to a continuous or substantially-continuous load-carrying surface or to a series of individual load-carriers; Endless-chain conveyors in which the chains form the load-carrying surface
- B65G17/12—Conveyors having an endless traction element, e.g. a chain, transmitting movement to a continuous or substantially-continuous load-carrying surface or to a series of individual load-carriers; Endless-chain conveyors in which the chains form the load-carrying surface comprising a series of individual load-carriers fixed, or normally fixed, relative to traction element
- B65G17/126—Bucket elevators
-
- 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
- B65G2201/00—Indexing codes relating to handling devices, e.g. conveyors, characterised by the type of product or load being conveyed or handled
- B65G2201/04—Bulk
Abstract
GRAIN LIFTING AND DISCHARGE APPARATUS
ABSTRACT OF THE DISCLOSURE
Apparatus is disclosed for the lifting and discharging of grain employing plug flow to minimize grain damage, dusting and wear and tear. A belt carrying lightweight buckets is operated at relatively low speed and is trained around a head and a tail pulley. The lip of the buckets projects outwardly from the belt surface a predetermined distance. The speed of the belt, the effective diameter of the head pulley and the bucket projection from the belt and are correlated.
to provide the desired discharge flow from the buckets.
ABSTRACT OF THE DISCLOSURE
Apparatus is disclosed for the lifting and discharging of grain employing plug flow to minimize grain damage, dusting and wear and tear. A belt carrying lightweight buckets is operated at relatively low speed and is trained around a head and a tail pulley. The lip of the buckets projects outwardly from the belt surface a predetermined distance. The speed of the belt, the effective diameter of the head pulley and the bucket projection from the belt and are correlated.
to provide the desired discharge flow from the buckets.
Description
RAIN LIFTING AMD DISCHARGE APPARATUS
ACK~ROUND OF THE IN~ENTION
For many years, it has been necessary to lift ~rain an~ discharge it into various kinds of S receptacles, such as storage bins, silos, hoppers and the like. This has been done by belts to which have bePn attached metal buckets for carrying the grain~ ~he belts have run at high speed over a pair of vertically spaced pulleys. The buckets on the belt dip into a reservoir of grain, which is usually continuously replenished, and travel generally vertically upwardly.
At the top of the run of the belt, the belt travels over the top or head pulley and returns downwardly thereby throwing the grain ~rom the buckets into a collection ~zone or chute from which the grain is discharged through a-spout into a desired receptacle.
Of major importance in the design of grain lifting and discharge apparatus is the ability to maintain a high volume throughput of material. Often, the apparatus is required to maintain a flow rate of as much as 60, ono bushels per hour. In order to achieve such efficient operation, the buckets, which have generally been of metal fabrication, are made to travel at high speed. ~owever, the high speed causes excessive dusting, grain damage and substantial wear and tear of the apparatus. Heretofore, a high volume throughput could not be obtained by the use of larger volume buckets ~ravelling at a lower speed. This is ~ecau.se commercially available belts are not presently capable of withs~anding the stresses created by the increased weight of larger metal buckets. Lower bucket speed is desirable since it reduces wear and tear on the apparatus and permits plug ~low, thereby reducing damage to the grain.
Accordingly, it is a main object of this ~6~
invention to provide improved apparatus which can handle substantial volumes of grain with less dusting, reduced grain damage, and minimum wear and tear to the apparatus.
According to the present invention there is provided an apparatus for conveying, lifting and discharging grain by plug flow, with reduced dusting, spraying, damage to grain and wear, the apparatus being adapted to run at low belt speeds while maintaining high volume throughpuk.
The apparatus has a belt driven at speed S, a head pulley having an effective diameter of D' inches and a tail pulley with the belt being trained around the pulleys. A plurality of buckets is mounted transversely of the direction of travel of the belt, the buckets having a lip projecting P inches from the belt, the buckets transporting the grain at the speed, and discharging the grain b~ plug flow as the buckets travel over the head pulley thereby minimizing dusting, spraying and grain damage. I'he speed S has a value from about .95 x ~ feet per second to about 69~5D' ~ ' + 2P
1.05 x ~D' + ~p feet per second. Driving means is provided for moving the belt at speed S.
More specifically the invention comprises a generally vertically travelling belt which may extend upwardly more than 200 feet. The belt travels between the lower or tail pulley located in the region of a grain reservoir or boot and the upper or head pulley located adjacent a discharge chute. The belt and pulleys are generally enclosed within a housing. Attached to the belt at spaced intervals are .~
68~1 the buckets which may be lightweight urethane. The buckets project outwardly a predetermined dis-tance from the belt to the bucket lip. The diameter of the head pulley, the speed of the belt, and the outward projection of the bucket lip from the belt are all correlated to achieve plug flow of grain from the buckets thereby minimizing grain damage and dus-ting. A high volume throughput can be maintained at much lower belt speeds with resulting minimization of wear and tear on the apparatus. The use of urethane buckets in the apparatus combines strength and durability with light weight so that the various features of the invention can be enjoyed. More particularly, the urethane buckets permit each bucket to .
- 2a -carry large volumes of yrain so that a high volume throughput can be achieved in combination with plug flow of the grain.
It will be understood that various equivalents 5 may he provided once the parameters of this invention are perceived and these variations can be extrapolated from the data provided in this Specification~ .
Plug flow and efficient operation has been achieved in commercial operations at a belt speed of about 450 feet per minute which i8 about one-half the bel~ speed heretofore used in lifting grain. The belt travels over a head pulley having a diameter of about 60 inches. The buckets are attached to the belt on 14 inch centers by means of bolts~ The buckets are fabricated from urethane, weigh about 30 pounds each, and project outwardly from the bel~ to the bucket lip abou~ 1~
inches. Each bucket i5 about 29 inches wide and 13 i~ches deep, and has capaci~y of about 1.5 bushels (3100 cubic inches).
In the event that a different head pulley diameter is used or that the bucket: extension from the belt is changed, the belt speed should be adjusted to achieve ~he desired grain flow. ~he point is that the belt speed, the projection of the bucket from the belt ~o.the bucket lip and the pulley diameter are functionally related to provide plug flow. The use of urethane buckets permits the handliny of increased volumes per bucket and thereby makes possible the advantages of the invention.
Belts are commercially available in 60 inch widths so that two buckets can be attached to the belt in two rows~ The buckets in the respective rows are s~aggered to achieve balance in operating. However, this additiorlal row oE buckets is not a special feature of this in~ention.
-BRIEF DESCRIPTION OF THE DRAWINGS
FIGURE 1 is a side elevational view of the grain lifting and discharge apparatus of the invention with portions broken away to show parts contained within the housing.
~ IGURE 2 is a view taken along line A-A in Figure 1 showing the buckets on the belt.
FIGURE 3 is a side view of the internal portion of the top section of the grain lifting and discharge apparatus of the invention showing the buckets travelling over the head pulley and the grain being discharged in the plug flow conditivn.
FIGURE 4 is also a side view of an internal portion of the top section of a grain lifting and discharge apparatus, similar to Figure 3, but having an old~ small bucket design and showing the grain being discharged in a rapid non-plug flow condition.
FIGURE 5 is a perspective view o~ a large urethane bu~ket.
FIGURE 6 is a graph of belt speed as a function of effective head pulley diameter for the generation of plug flow from buckets having a 16 inch projection.
DESCRIPTION OF THE PREF RRED EMBODIMENT
Now referring to the drawings, there is illustrated a commercial embodiment of the invention.
The apparatus c com~rises a casing 11, made generally of 12-~uage steel, which is generally rectangular in cross section. At the bottom of the casing 11 is provided a boot 13 which serves as a grain reservoir. Grain is continuously fed into the boot by a feed spout 15. At the top of the casing 11 there is provided a discharge chute 17 which terminates in a discharge spout 19. The ~asing 11 is ~bout ~20 feet in height and is provided throughout its vertical extent with access panels and doors (not shown) for repair and maintenance purposes.
Journaled at the bottom of the casing 11 is a bottom or tail pulley 21 and at the top of the casing 11 there is journaled a top or head pulley 23, which is located above the discharge chute 17. A bel~ 2~, which is commercially available, is trained around the pulleys 21 and 23. The belt 25 is driven in a conventional manner by a 500 horsepower motox (not shown). In the illustrated embodiment~ the belt 25 i5 60 inches wide and is driven at a speed of about 450 feet per minute.
The diameter of the tail pulley 21 is not particularly critical to the operation of the apparatus o~ the invention but in the apparatus shown in the drawings, is 42 inches in diameter. The diameter of the head pulley shown in the drawings is ~0 inches in 15 diameter. As before indicated, the diameter of the head pulley 23 is important in relation to belt speed and the projection of the bucket lip from t:he belt surface.
Attached to the belt 25 are a series of transversely mounted buckets 27 for picking up grain in the boot 13, transporting the grain to the top of the casing 11, and discharging the grain to the discharge chute 17. In Figure 5, the configLlration of the bucke~s 27 i5 shown. The buckets 27 are relatively light in weight, being fabricated from urethane, and weigh about 30 pounds eachO The rear wall 28 of each bucket 27 is bolted to the belt 25. The buckets 27 are located on 14 inch centers. The buckets 27 are 29 inches wide and the front wall 30 extends outwardly and is 16 inches from the belt surface at its lip 31 which is an important 30 dimension for purposes of this invention. Gussets 42 provide the buckets 27 with strength and rigidity. The buckets are 13 inches in depth.
The buckets 27 are dimensioned to provide a grain capacity of 1.5 bushels (3100 cubic inches) and 35 front walls 30 of the buck~ts 27 are angled with respect to the rear wall 28 to facilitate loading and emp~ying .
Because the bucket 27 has a depth of 13 inches, there is a space of about 1 inch between the bottom of one bucket ~7 and the top of the following bucket. In the apparatus, as shown in Fig. ~, ~here are two rows of buckets 27 on the belt 25, thereby doubling the capacity Qf the apparatus. The buckets 27 in each row are staggered to provide balance to the belt.
I~ is also important that the buckets 27 be 10 made of a lightweight material that has the ability to withstand wear during operation. One such material is urethane. Urethane buckets provide a unique combi~ation of features for this invention by allowing high volume throughput at a belt speed slow enough to provide plug lS flow.
In operation, the boot 13 is continuously fed wi h grain to provide a reservoir of grain. The buckets 27 attached to the belt 25, enter the grain reservoir and scoop up the grain as they move upwardly from the tail pulley 210 The buckets 27 travel upwardly and over the head pulley 23 causing the grain to be thrown from the buckets 27 into the chute 17 and out of the spout 19. As the grain is discharged from the buckets 27, it leaves under plug flow ~onditions (Fig. 3).
The plug flow condition of the grain flow, as it is discharged from the buckets 27, is obtained by correlating the belt speed, head pulley diameter and the pxojection of the bucket lip 31 from the belt 25 surface. Buckets 27 loaded with grain 33 are shown travelling upward toward the head pulley 23 on the right-hand portion of the belt 25 in Fig. 3. By correlating the above-mentioned parameters/ as the bucket travels over the head pulley 23, the radial acceleration on a kernel of grain located at the lip 31 of the bucket 27 is balanced with the acceleration due to gravityO Ideally ~hen, the kernel of grain should remain motionless with respect to the bucket 27 until the orientation of the loaded bucket 27 has changed at least 90. Some minor movement may, however, actually occur prior to this time primarily due to the angled relationship between the front 30 and rear 28 walls of the buckets 27. In any event, as the bucket 27 continues its path over the head pulley 23, the angled front wall 30 produces an outward resultant force from the centrifugal force acting on the grain~ The grain is then gently dischargedt en masse as a "plug" 35 into the discharge chute ~7 (not shown in Fig. 3).
Plug flow should be compared with grain discharge from conventional metal buckets 27' that have generally been of smal~er dimensions and operated with higher belt speeds to obtain comparable grain throughput (Fig~ 4). The buckets 27~ travelling over the head pulley at high speed ~end to "spray" the grain 33 in the area of the discharge chute 17 (not shown in Fig. 4).
Thus, the grain kernels collide with one another and the casing 11 causing damage to the grain and increasin~
dusting.
To correlate belt speed, head pulley diameter and bucket dimensions for obtaining pluq flow the following calculations are made. The radial acceleration (A) on a kernel of grain is given by the expression:
A= V~
where V = the tangential velocity of a kernel of grain in feet per second as the bucket passes over the head pulley; and where R = the radial distance of a kernel of grain from the head pulley center in feet.
~6818~
In plug flow the radîal acceleration A is e~ual to the acceleration of gravity so ~2 or R = g = 32.17 ft./sec.
V = ~ R
A kernel of grain located at the lip 31 of the bucket 27 (the furthest point from ~he head pulley center) under goes the greatest radial acceleration. In order to prevent the "spraying" of grain the radial acceleration on a kernel of grain at this location is balanced with that due to gravity. R is then a function of the head pulley diameter, D (measured in inches), and the projection of the bucket 27 from the surface of the ~elt 25 to the bucket lip 31, desîgnated as P ~measured - in inches). In grain lifting and discharge apparatus the belt 2S is often times up to one inch thick and the head pulley 23 may be provided with lagging (not shown) up to about an inch thick to help prevent ~elt slippage. These two factors can substan~ially e~fect the radial distance R so that the t:erm effective head pulley diameter, D', as used herein is meant to include the effect o~ belt thickness as well as lagging on R.
The radial distance7 R, is put in terms of effectiYe head pulley diameter, D', and bucket projection, P, as . ~ollows:
R =' 1 '[Dl + P] -- '('D'' -~' '2P) Similarly, ~ is put in terms of D', P, and belt speed, S
~measured in ft.~min.), as follows~ -60 [~~~
Therefore: 6S0 x ~ 8 -69,5D' S = _.
or r~
~ D~ ~ 2P
R~ferring now to Fig. 69 it can be seen tbat the solid line represents belt speed, S, plotted as a function of efective head pulley diameter~ D', for the generation of plug flow from buckets having a 16 inch projection, P. The two broken lines drawn on both sides ; . of the above mentioned solid line represent a permissible plus or minus five percent deviation in belt ~peed for a given ef~ective head pulley diameter.
Experimentation has shown that a plus or minus five percent deviation in belt speed from that predicted by ~he derived :Eormula will still produce plug flow conditions. Accordingly, experimental examples A .
through D have been plotted in Fig. 6 and are explained lS below.
In examples A and B plug f.low was obtained through the proper correlation of belt speed and effective head pu7ley diameter for a 16 inch bucket projection~ In Example A, a grain lifting and discharge apparatus was fitted with a 60 inch diameter head pulley and a belt thickness of 3/8 inch thus yeilding an ef~ective head pulley diameter of S0.75 inches. The aparatus was operated at a belt speed of 430 feet per minute and produced plug flow. In Example B, apparatus ~S having a 60 inch diameter head pulley, a belt thickness of 3/4 inch and one inch lagging was operated at a belt speed of 450 ~eet per minute. The effective head pulley diameter~ D', in Example B was 63-1/2 inchesO Grain discharge from the buckets in Example B was also in the plug flow condition.
In Examples C and D9 apparatus having a 60 inch 8.~
diameter head pulley, a belt thickness of 3/8 inch and no lagging failed to produce plug flow because of improper belt speed. In Example C, ~he apparatus was operated at a belt speed of 400 feet per minute. This proved to be too low and the grai~ spilled out before the buckets 27 reached the discharge chute 17 resulting in a condition known as "back-legging". In Example D, the apparatus was operated at a belt speed of 480 feet per minute which resulted in excessive spraying and throwing of the grain.
On the basis of Examples A through D, it was determined that a deviation in belt speed (for a given effective head pulley diameter and bucket projectio~) of about plus or minus five percent from that predicted by the derived formula will still produce plug flow of the grain upon discharge fxom the buckets.
To further illustrate the predictability of plug flow by the correlation of belt speed, bucket projection and effective head pulley diameter a grain lifting and discharge apparatus was fitted with a 42 inch diameter head pulley, a 3/8 inch thick belt, and buckets projecting 14 inches from ~he belt surface to the bucket lip. Plug flow of the grairl was observed, through the use of high speed photography, at a belt ~peed of 340 feet per minute. This compares very favorably with that predicted by the derived formula, about 353 feet-per minute. The belt speed at which plug flow was observed was within about 3.7 percent of that predicted~
As was previously mentioned, the use of urethane buckets permits the combination of high volume grain throughput and plug ~low in the grain lifting and discharge apparatus. Apparatus having a 60 inch diameter head pulley and two rcws of ~he 1.5 bushel capacity urethane buckets shown in Fig. 5 spaced on 14 ~8~
= 11-inch centers, operated at a belt speed of about 425 to 465 feet per minute has a throughput capacity of about 57,000 to 61,800 bushels per hour. Similarly, apparatus having bucket dimensions and spacing ~s described above and a 72 inch diameter head pulley, operated at a belt speed of about 475 to 525 feet per minute has a throughput capacity of about 63,000 ~o about 69,600 bushels per hours. These high volume throughputs are obtained in combination with the reduced dusting and grain damage attributable to plug flow.
It should be understood that although certain preferred embodiments of the present inven~ion have been illustrated and described, various modifications, alternatives and equivalents thereof will beco~e apparent to those skilled in the art and, accardingly, the scope o~ the present invention sho~ld be defined only by the appended claims and equivalents thereof.
Various features of the invention are set forth in the following claims.
ACK~ROUND OF THE IN~ENTION
For many years, it has been necessary to lift ~rain an~ discharge it into various kinds of S receptacles, such as storage bins, silos, hoppers and the like. This has been done by belts to which have bePn attached metal buckets for carrying the grain~ ~he belts have run at high speed over a pair of vertically spaced pulleys. The buckets on the belt dip into a reservoir of grain, which is usually continuously replenished, and travel generally vertically upwardly.
At the top of the run of the belt, the belt travels over the top or head pulley and returns downwardly thereby throwing the grain ~rom the buckets into a collection ~zone or chute from which the grain is discharged through a-spout into a desired receptacle.
Of major importance in the design of grain lifting and discharge apparatus is the ability to maintain a high volume throughput of material. Often, the apparatus is required to maintain a flow rate of as much as 60, ono bushels per hour. In order to achieve such efficient operation, the buckets, which have generally been of metal fabrication, are made to travel at high speed. ~owever, the high speed causes excessive dusting, grain damage and substantial wear and tear of the apparatus. Heretofore, a high volume throughput could not be obtained by the use of larger volume buckets ~ravelling at a lower speed. This is ~ecau.se commercially available belts are not presently capable of withs~anding the stresses created by the increased weight of larger metal buckets. Lower bucket speed is desirable since it reduces wear and tear on the apparatus and permits plug ~low, thereby reducing damage to the grain.
Accordingly, it is a main object of this ~6~
invention to provide improved apparatus which can handle substantial volumes of grain with less dusting, reduced grain damage, and minimum wear and tear to the apparatus.
According to the present invention there is provided an apparatus for conveying, lifting and discharging grain by plug flow, with reduced dusting, spraying, damage to grain and wear, the apparatus being adapted to run at low belt speeds while maintaining high volume throughpuk.
The apparatus has a belt driven at speed S, a head pulley having an effective diameter of D' inches and a tail pulley with the belt being trained around the pulleys. A plurality of buckets is mounted transversely of the direction of travel of the belt, the buckets having a lip projecting P inches from the belt, the buckets transporting the grain at the speed, and discharging the grain b~ plug flow as the buckets travel over the head pulley thereby minimizing dusting, spraying and grain damage. I'he speed S has a value from about .95 x ~ feet per second to about 69~5D' ~ ' + 2P
1.05 x ~D' + ~p feet per second. Driving means is provided for moving the belt at speed S.
More specifically the invention comprises a generally vertically travelling belt which may extend upwardly more than 200 feet. The belt travels between the lower or tail pulley located in the region of a grain reservoir or boot and the upper or head pulley located adjacent a discharge chute. The belt and pulleys are generally enclosed within a housing. Attached to the belt at spaced intervals are .~
68~1 the buckets which may be lightweight urethane. The buckets project outwardly a predetermined dis-tance from the belt to the bucket lip. The diameter of the head pulley, the speed of the belt, and the outward projection of the bucket lip from the belt are all correlated to achieve plug flow of grain from the buckets thereby minimizing grain damage and dus-ting. A high volume throughput can be maintained at much lower belt speeds with resulting minimization of wear and tear on the apparatus. The use of urethane buckets in the apparatus combines strength and durability with light weight so that the various features of the invention can be enjoyed. More particularly, the urethane buckets permit each bucket to .
- 2a -carry large volumes of yrain so that a high volume throughput can be achieved in combination with plug flow of the grain.
It will be understood that various equivalents 5 may he provided once the parameters of this invention are perceived and these variations can be extrapolated from the data provided in this Specification~ .
Plug flow and efficient operation has been achieved in commercial operations at a belt speed of about 450 feet per minute which i8 about one-half the bel~ speed heretofore used in lifting grain. The belt travels over a head pulley having a diameter of about 60 inches. The buckets are attached to the belt on 14 inch centers by means of bolts~ The buckets are fabricated from urethane, weigh about 30 pounds each, and project outwardly from the bel~ to the bucket lip abou~ 1~
inches. Each bucket i5 about 29 inches wide and 13 i~ches deep, and has capaci~y of about 1.5 bushels (3100 cubic inches).
In the event that a different head pulley diameter is used or that the bucket: extension from the belt is changed, the belt speed should be adjusted to achieve ~he desired grain flow. ~he point is that the belt speed, the projection of the bucket from the belt ~o.the bucket lip and the pulley diameter are functionally related to provide plug flow. The use of urethane buckets permits the handliny of increased volumes per bucket and thereby makes possible the advantages of the invention.
Belts are commercially available in 60 inch widths so that two buckets can be attached to the belt in two rows~ The buckets in the respective rows are s~aggered to achieve balance in operating. However, this additiorlal row oE buckets is not a special feature of this in~ention.
-BRIEF DESCRIPTION OF THE DRAWINGS
FIGURE 1 is a side elevational view of the grain lifting and discharge apparatus of the invention with portions broken away to show parts contained within the housing.
~ IGURE 2 is a view taken along line A-A in Figure 1 showing the buckets on the belt.
FIGURE 3 is a side view of the internal portion of the top section of the grain lifting and discharge apparatus of the invention showing the buckets travelling over the head pulley and the grain being discharged in the plug flow conditivn.
FIGURE 4 is also a side view of an internal portion of the top section of a grain lifting and discharge apparatus, similar to Figure 3, but having an old~ small bucket design and showing the grain being discharged in a rapid non-plug flow condition.
FIGURE 5 is a perspective view o~ a large urethane bu~ket.
FIGURE 6 is a graph of belt speed as a function of effective head pulley diameter for the generation of plug flow from buckets having a 16 inch projection.
DESCRIPTION OF THE PREF RRED EMBODIMENT
Now referring to the drawings, there is illustrated a commercial embodiment of the invention.
The apparatus c com~rises a casing 11, made generally of 12-~uage steel, which is generally rectangular in cross section. At the bottom of the casing 11 is provided a boot 13 which serves as a grain reservoir. Grain is continuously fed into the boot by a feed spout 15. At the top of the casing 11 there is provided a discharge chute 17 which terminates in a discharge spout 19. The ~asing 11 is ~bout ~20 feet in height and is provided throughout its vertical extent with access panels and doors (not shown) for repair and maintenance purposes.
Journaled at the bottom of the casing 11 is a bottom or tail pulley 21 and at the top of the casing 11 there is journaled a top or head pulley 23, which is located above the discharge chute 17. A bel~ 2~, which is commercially available, is trained around the pulleys 21 and 23. The belt 25 is driven in a conventional manner by a 500 horsepower motox (not shown). In the illustrated embodiment~ the belt 25 i5 60 inches wide and is driven at a speed of about 450 feet per minute.
The diameter of the tail pulley 21 is not particularly critical to the operation of the apparatus o~ the invention but in the apparatus shown in the drawings, is 42 inches in diameter. The diameter of the head pulley shown in the drawings is ~0 inches in 15 diameter. As before indicated, the diameter of the head pulley 23 is important in relation to belt speed and the projection of the bucket lip from t:he belt surface.
Attached to the belt 25 are a series of transversely mounted buckets 27 for picking up grain in the boot 13, transporting the grain to the top of the casing 11, and discharging the grain to the discharge chute 17. In Figure 5, the configLlration of the bucke~s 27 i5 shown. The buckets 27 are relatively light in weight, being fabricated from urethane, and weigh about 30 pounds eachO The rear wall 28 of each bucket 27 is bolted to the belt 25. The buckets 27 are located on 14 inch centers. The buckets 27 are 29 inches wide and the front wall 30 extends outwardly and is 16 inches from the belt surface at its lip 31 which is an important 30 dimension for purposes of this invention. Gussets 42 provide the buckets 27 with strength and rigidity. The buckets are 13 inches in depth.
The buckets 27 are dimensioned to provide a grain capacity of 1.5 bushels (3100 cubic inches) and 35 front walls 30 of the buck~ts 27 are angled with respect to the rear wall 28 to facilitate loading and emp~ying .
Because the bucket 27 has a depth of 13 inches, there is a space of about 1 inch between the bottom of one bucket ~7 and the top of the following bucket. In the apparatus, as shown in Fig. ~, ~here are two rows of buckets 27 on the belt 25, thereby doubling the capacity Qf the apparatus. The buckets 27 in each row are staggered to provide balance to the belt.
I~ is also important that the buckets 27 be 10 made of a lightweight material that has the ability to withstand wear during operation. One such material is urethane. Urethane buckets provide a unique combi~ation of features for this invention by allowing high volume throughput at a belt speed slow enough to provide plug lS flow.
In operation, the boot 13 is continuously fed wi h grain to provide a reservoir of grain. The buckets 27 attached to the belt 25, enter the grain reservoir and scoop up the grain as they move upwardly from the tail pulley 210 The buckets 27 travel upwardly and over the head pulley 23 causing the grain to be thrown from the buckets 27 into the chute 17 and out of the spout 19. As the grain is discharged from the buckets 27, it leaves under plug flow ~onditions (Fig. 3).
The plug flow condition of the grain flow, as it is discharged from the buckets 27, is obtained by correlating the belt speed, head pulley diameter and the pxojection of the bucket lip 31 from the belt 25 surface. Buckets 27 loaded with grain 33 are shown travelling upward toward the head pulley 23 on the right-hand portion of the belt 25 in Fig. 3. By correlating the above-mentioned parameters/ as the bucket travels over the head pulley 23, the radial acceleration on a kernel of grain located at the lip 31 of the bucket 27 is balanced with the acceleration due to gravityO Ideally ~hen, the kernel of grain should remain motionless with respect to the bucket 27 until the orientation of the loaded bucket 27 has changed at least 90. Some minor movement may, however, actually occur prior to this time primarily due to the angled relationship between the front 30 and rear 28 walls of the buckets 27. In any event, as the bucket 27 continues its path over the head pulley 23, the angled front wall 30 produces an outward resultant force from the centrifugal force acting on the grain~ The grain is then gently dischargedt en masse as a "plug" 35 into the discharge chute ~7 (not shown in Fig. 3).
Plug flow should be compared with grain discharge from conventional metal buckets 27' that have generally been of smal~er dimensions and operated with higher belt speeds to obtain comparable grain throughput (Fig~ 4). The buckets 27~ travelling over the head pulley at high speed ~end to "spray" the grain 33 in the area of the discharge chute 17 (not shown in Fig. 4).
Thus, the grain kernels collide with one another and the casing 11 causing damage to the grain and increasin~
dusting.
To correlate belt speed, head pulley diameter and bucket dimensions for obtaining pluq flow the following calculations are made. The radial acceleration (A) on a kernel of grain is given by the expression:
A= V~
where V = the tangential velocity of a kernel of grain in feet per second as the bucket passes over the head pulley; and where R = the radial distance of a kernel of grain from the head pulley center in feet.
~6818~
In plug flow the radîal acceleration A is e~ual to the acceleration of gravity so ~2 or R = g = 32.17 ft./sec.
V = ~ R
A kernel of grain located at the lip 31 of the bucket 27 (the furthest point from ~he head pulley center) under goes the greatest radial acceleration. In order to prevent the "spraying" of grain the radial acceleration on a kernel of grain at this location is balanced with that due to gravity. R is then a function of the head pulley diameter, D (measured in inches), and the projection of the bucket 27 from the surface of the ~elt 25 to the bucket lip 31, desîgnated as P ~measured - in inches). In grain lifting and discharge apparatus the belt 2S is often times up to one inch thick and the head pulley 23 may be provided with lagging (not shown) up to about an inch thick to help prevent ~elt slippage. These two factors can substan~ially e~fect the radial distance R so that the t:erm effective head pulley diameter, D', as used herein is meant to include the effect o~ belt thickness as well as lagging on R.
The radial distance7 R, is put in terms of effectiYe head pulley diameter, D', and bucket projection, P, as . ~ollows:
R =' 1 '[Dl + P] -- '('D'' -~' '2P) Similarly, ~ is put in terms of D', P, and belt speed, S
~measured in ft.~min.), as follows~ -60 [~~~
Therefore: 6S0 x ~ 8 -69,5D' S = _.
or r~
~ D~ ~ 2P
R~ferring now to Fig. 69 it can be seen tbat the solid line represents belt speed, S, plotted as a function of efective head pulley diameter~ D', for the generation of plug flow from buckets having a 16 inch projection, P. The two broken lines drawn on both sides ; . of the above mentioned solid line represent a permissible plus or minus five percent deviation in belt ~peed for a given ef~ective head pulley diameter.
Experimentation has shown that a plus or minus five percent deviation in belt speed from that predicted by ~he derived :Eormula will still produce plug flow conditions. Accordingly, experimental examples A .
through D have been plotted in Fig. 6 and are explained lS below.
In examples A and B plug f.low was obtained through the proper correlation of belt speed and effective head pu7ley diameter for a 16 inch bucket projection~ In Example A, a grain lifting and discharge apparatus was fitted with a 60 inch diameter head pulley and a belt thickness of 3/8 inch thus yeilding an ef~ective head pulley diameter of S0.75 inches. The aparatus was operated at a belt speed of 430 feet per minute and produced plug flow. In Example B, apparatus ~S having a 60 inch diameter head pulley, a belt thickness of 3/4 inch and one inch lagging was operated at a belt speed of 450 ~eet per minute. The effective head pulley diameter~ D', in Example B was 63-1/2 inchesO Grain discharge from the buckets in Example B was also in the plug flow condition.
In Examples C and D9 apparatus having a 60 inch 8.~
diameter head pulley, a belt thickness of 3/8 inch and no lagging failed to produce plug flow because of improper belt speed. In Example C, ~he apparatus was operated at a belt speed of 400 feet per minute. This proved to be too low and the grai~ spilled out before the buckets 27 reached the discharge chute 17 resulting in a condition known as "back-legging". In Example D, the apparatus was operated at a belt speed of 480 feet per minute which resulted in excessive spraying and throwing of the grain.
On the basis of Examples A through D, it was determined that a deviation in belt speed (for a given effective head pulley diameter and bucket projectio~) of about plus or minus five percent from that predicted by the derived formula will still produce plug flow of the grain upon discharge fxom the buckets.
To further illustrate the predictability of plug flow by the correlation of belt speed, bucket projection and effective head pulley diameter a grain lifting and discharge apparatus was fitted with a 42 inch diameter head pulley, a 3/8 inch thick belt, and buckets projecting 14 inches from ~he belt surface to the bucket lip. Plug flow of the grairl was observed, through the use of high speed photography, at a belt ~peed of 340 feet per minute. This compares very favorably with that predicted by the derived formula, about 353 feet-per minute. The belt speed at which plug flow was observed was within about 3.7 percent of that predicted~
As was previously mentioned, the use of urethane buckets permits the combination of high volume grain throughput and plug ~low in the grain lifting and discharge apparatus. Apparatus having a 60 inch diameter head pulley and two rcws of ~he 1.5 bushel capacity urethane buckets shown in Fig. 5 spaced on 14 ~8~
= 11-inch centers, operated at a belt speed of about 425 to 465 feet per minute has a throughput capacity of about 57,000 to 61,800 bushels per hour. Similarly, apparatus having bucket dimensions and spacing ~s described above and a 72 inch diameter head pulley, operated at a belt speed of about 475 to 525 feet per minute has a throughput capacity of about 63,000 ~o about 69,600 bushels per hours. These high volume throughputs are obtained in combination with the reduced dusting and grain damage attributable to plug flow.
It should be understood that although certain preferred embodiments of the present inven~ion have been illustrated and described, various modifications, alternatives and equivalents thereof will beco~e apparent to those skilled in the art and, accardingly, the scope o~ the present invention sho~ld be defined only by the appended claims and equivalents thereof.
Various features of the invention are set forth in the following claims.
Claims (14)
- Claim 1. Apparatus for conveying, lifting and discharging grain by plug flow, with reduced dusting, spraying, damage to grain and wear, said apparatus being adapted to run at low belt speeds while maintaining high volume throughput, said apparatus comprising:
a belt driven at speed S;
a head pulley having an effective diameter of D' inches;
a tail pulley;
said belt being trained around said pulleys a plurality of buckets mounted transversely of the direction of travel of said belt;
said buckets having a lip projecting P inches from said belt, said buckets transporting said grain at said speed, and discharging said grain by plug flow as said buckets travel over said head pulley thereby minimizing dusting, spraying and grain damage;
said speed S having a value of from about feet per second to about feet per second;
and driving means for moving said belt at speed S. - Claim 2. Apparatus for the conveying, lifting and discharging grain, with plug flow, with reduced dusting, spraying, damage to grain and wear, said apparatus being adapted to run at low belt speeds while maintaining high volume throughput, said apparatus comprising:
a belt driven at speed S, a head pulley having an effective diamater of D' inches;
a tail pulley;
said belt being trained around said pulleys;
a plurality of buckets mounted transversely of the direction of travel of said belt;
said buckets having a lip projecting a predetermined distance P inches from said belt, said buckets transporting said grain at said speed S when passing about said head pulley to substantially balance the radial acceleration of said discharging grain with gravity to minimize dusting, grain spray and grain damage;
said predetermined speed having a value of from about feet per second to about feet per second providing plug flow of said grain from said buckets; and means for moving said belt at said predetermined speed. - Claim 3. Apparatus in accordance with Claim 1 or 2 wherein said buckets are fabricated from urethane.
- Claim 4. Apparatus in accordance with Claims 1 or 2 wherein said pulley has a diameter between about 10 inches and about 72 inches and said predetermined effective diameter is between about 10 inches and about 76 inches.
- Claim 5. Apparatus in accordance with Claims 1 or 2 wherein said predetermined distance P is between about 2 inches and about 48 inches.
- Claim 6. apparatus in accordance with Claims 1 or 2 wherein said buckets have a grain capacity between about .005 bushels and about 120 bushels.
- Claim 7. Apparatus in accordance with Claims 1 or 2 wherein said apparatus has a throughput capacity between about 120 bushels per hour and about 120,000 bushels per hour.
- Claim 8. A method for transporting grain in high volumes by plug flow with reduced dusting, reduced grain damage and minimum wear and tear to a grain transporting apparatus which includes a belt trained around a head pulley, a tail pulley, said belt having a plurality of buckets mounted transversely of the direction of travel of the belt, said method comprising:
providing the head pulley with an effective diameter D' inches;
providing the buckets with lips projecting a predetermined distance of P inches from the belt;
moving the belt at a speed S, of from about feet per second to about feet per second;
discharging said grain in mass as a plug from the buckets as the buckets move over the head pulley, said discharge providing a minimum dusting, spraying and damage to the grain. - Claim 9. A method as set forth in Claim 8 wherein the buckets upon passing about said head pulley cause the grain to be transported at said bucket lips at a radial acceleration substantially balanced with gravity.
- Claim 10. A method in accordance with Claims 8 or 9 wherein said buckets are fabricated from urethane.
- Claim 11. A method in accordance with Claims 8 or 9 wherein the head pulley has a diameter between about 10 inches and about 72 inches and said effective diameter is between about 10 inches about 76 inches.
- Claim 12. A method in accordance with Claims 8 or 9 wherein said distance P is between about 2 inches and about 48 inches.
- Claim 13. A method in accordance with Claims 8 or 9 wherein said buckets have a grain capacity between about .005 bushels and about 120 bushels.
- Claim 14. A method in accordance with Claims 8 or 9 wherein said apparatus has a throughput capacity between about 120 bushels per hour and about 120,000 bushels per hour.
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US16855480A | 1980-07-14 | 1980-07-14 | |
| US168,554 | 1980-07-14 | ||
| US28310881A | 1981-07-13 | 1981-07-13 | |
| US283,108 | 1981-07-13 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1168181A true CA1168181A (en) | 1984-05-29 |
Family
ID=26864242
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000381700A Expired CA1168181A (en) | 1980-07-14 | 1981-07-14 | Grain lifting and discharge apparatus |
Country Status (4)
| Country | Link |
|---|---|
| AU (1) | AU543690B2 (en) |
| BR (1) | BR8108702A (en) |
| CA (1) | CA1168181A (en) |
| WO (1) | WO1982000282A1 (en) |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1210662A (en) * | 1915-12-30 | 1917-01-02 | Arthur D Mcpherson | Attaching-hanger for elevator-buckets. |
| US1295154A (en) * | 1918-10-30 | 1919-02-25 | Moline Mill Mfg Company | Elevator-cup. |
| US2122036A (en) * | 1937-05-13 | 1938-06-28 | K I Willis Corp | Elevator cup |
| US2370531A (en) * | 1942-08-24 | 1945-02-27 | Webster Mfg Inc | Elevator bucket |
| US2557325A (en) * | 1947-12-31 | 1951-06-19 | Sherman T Transeau | Bucket elevator |
| US3319774A (en) * | 1965-10-05 | 1967-05-16 | Lester B Knight & Associates I | Elevating conveyor |
-
1981
- 1981-07-14 BR BR8108702A patent/BR8108702A/en unknown
- 1981-07-14 AU AU74532/81A patent/AU543690B2/en not_active Ceased
- 1981-07-14 CA CA000381700A patent/CA1168181A/en not_active Expired
- 1981-07-14 WO PCT/US1981/000947 patent/WO1982000282A1/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| WO1982000282A1 (en) | 1982-02-04 |
| AU7453281A (en) | 1982-02-16 |
| AU543690B2 (en) | 1985-04-26 |
| BR8108702A (en) | 1982-06-01 |
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| Date | Code | Title | Description |
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| MKEX | Expiry |