Trommel

Information

  • Patent Grant
  • 6609617
  • Patent Number
    6,609,617
  • Date Filed
    Monday, April 8, 2002
    22 years ago
  • Date Issued
    Tuesday, August 26, 2003
    21 years ago
Abstract
A trommel for classifying and sorting objects. The trommel is an open cylinder including a drive plate and a feed plate. A series of supporting rods extend between the drive plate and the feed plate. Disposed therebetween is a rod support ring dividing the trommel into a classifying zone and a discharge zone. A plurality of vibrating rods, floating in the vicinity of the rod support ring and anchored to the feed plate, oscillate and flex as the trommel rotates causing preselected sized objects to pass through the vibrating and support bars while the remaining objects are passed into the discharge zone with reduced clogging.
Description




TECHNICAL FIELD




The present invention relates to classifying equipment in general, and more particularly, to an apparatus that separates preselected undersize object fractions, such as chunks, pellets, briquettes, aggregate, rocks, grain, seeds and the like from preselected oversized object fractions of the same or differing material.




BACKGROUND OF THE INVENTION




Classifying devices are utilized to sort, grade and separate diverse sizes of commingled solids in a myriad of applications.




A relatively simple sorting device is represented by a screen. Depending on the chosen spacing of the mesh, a percentage of the solids of a desired maximum size are permitted to pass whereas the remaining larger components are restrained. Vibratory screens or grizzlies expedite the sorting process. Screens are prone to debilitating plugging and downtime.




For classifying larger objects, rotating drums having circumferentially spaced longitudinal bars permit desired sized objects to pass through the spacing of the bars for collection whereas the remaining larger articles continue through the drum.




Improvements to drum classifiers generally relate to complex mechanical mechanisms for moving the bars.




Representative designs include U.S. Pat. No. 2,984,351 to Van Slyck et al. wherein a plurality of sizing tubes or bars are rotatably mounted within rings.




U.S. Pat. No. 3,055,500 to Aubert-Maguero discloses a cylindrical cage having variable gaps between the bars to free jammed articles.




Bean graders of the type disclosed in U.S. Pat. No. 3,241,667 to Grosbety and U.S. Pat. No. 5,332,103 to Zittel disclose rotating drums having spring loaded spacing mechanisms for bars and rotatable grader bars respectively.




SU 1238-808 appears to be classifying drum suspended by springs.




U.S. Pat. No. 883,974 to Roughsedge discloses a rotating drum having rigid bars alternating with shiftable free bars constrained in space rings. The larger fractions are caused to erosively flow over an inner space ring as the drum rotates.




Applicants' previous experience with a stationary grizzly resulted in significant exasperating and expensive downtime. Assignee produces carbonyl nickel pellets. Fused nickel pellet chunks (called “elephants”) tended to clog up the grizzly wire screens upon their exit from a furnace. The operation had to be repeatedly stopped and the plugging elephants physically removed by hand. A review of drum designs revealed complicated mechanical classifiers (such as those referenced above) that would be expected to experience periodic jamming in dusty and dirty industrial environments.




SUMMARY OF THE INVENTION




There is provided a refreshingly simple but robust drum classifier or trommel that easily divides solids into larger and smaller sized fractions in a demanding duty environment.




The trommel is an open cylinder including a plurality of longitudinal rods extending between two opposed end plates. The ends of a plurality of selected shorter rods are affixed to one end plate whereas the opposing unattached ends of these selected rods float in an opposing ring disposed between the two end plates. As the drum rotates and the objects impact all of the rods, the selected rods oscillate and vibrate in essentially infinite degrees of freedom so as to continuously alter their spaced relationship with each other as well as their fixed rod neighbors. The infinitely continuous vibrating motion size screens the objects with reduced plugging.











BRIEF DESCRIPTION OF THE DRAWINGS





FIG. 1

is an elevation of an embodiment of the invention.





FIG. 2

is a view taken along line


2





2


in FIG.


1


.





FIG. 3

is a view taken along line


3





3


in FIG.


1


.





FIG. 4

is a view taken along line


4





4


in FIG.


1


.





FIG. 5

is a view of an alternative embodiment of the invention.





FIG. 6

is a schematic view of an embodiment of the invention in partial cross section.





FIG. 7

is a schematic alternative embodiment of the invention.





FIG. 8

is a schematic alternative embodiment of the invention.











PREFERRED EMBODIMENT OF THE INVENTION




Referring to

FIG. 1

there is shown a trommel


10


. The trommel


10


includes drive plate


12


located at the distal end


14


of the trommel


10


. A feed plate


16


is disposed at the proximal end


18


of the trommel


10


.




The terms ‘distal” and “proximal” are arbitrary conventions useful for ease of discussion. They are not to be construed as limiting.




The drive plate


12


includes a plurality of spaced circumferentially disposed feed plate holes


20


and a center drive hole


22


. See also FIG.


2


.




The feed plate


16


includes plurality of circumferentially disposed drive plate holes


24


and a center opening


26


. See also FIG.


4


.




A plurality of spaced supporting rods


28


extend longitudinally between the drive plate


12


and the feed plate


16


to form a substantially open drum cage. Although the supporting rods


28


are shown fastened to the plates


12


and


16


by double nuts


30


with lock washes (not shown), other attachment means such as welds, rivets, swaged ends, etc. may be used. Nuts


30


permit relatively easy assembly and disassembly whereas other fastening means are more permanent in nature. When using the nuts


30


, the ends of the supporting rods


28


are threaded (not shown).




A rod support ring


32


is disposed between the distal and proximal ends


14


and


18


of the trommel


10


simultaneously forming classifying zone


44


and discharge zone


34


. The location of the rod support


32


and hence the respective sizes of the classifying zone


44


and the discharge zone


34


may be selected as conditions and classifying needs change.




Turning to

FIG. 3

, the rod support ring


32


includes an inner surface or race


36


having a plurality circumferentially spaced first scallops


38


of a predetermined diameter. Interspaced between the first scallops


38


are a series of circumferentially spaced second scallops


40


. The second scallops


40


cradle the supporting rods


28


which may be welded or press fitted to the inner race


36


. The supporting rods


28


essentially extend over the entire length of the trommel


10


.




A plurality of spaced vibratory rods


42


longitudinally bridge the classifying zone


44


of the trommel


10


formed between the rod support ring


32


and the feed plate


16


.




The distal ends


46


of the vibrating rods


42


rest on or are spaced above the first scallops


38


but are not affixed to them. Collectively, the unrestrained distal ends


46


of the rods


42


are free to “float.” The opposing proximal ends


48


of the vibrating rods


42


are anchored to the feed plate


16


. Again, double nuts


30


are preferred but other fastening means are acceptable.




In operation, the trommel


10


rotates as the objects are introduced into the classifying zone


44


through the center opening


26


of the feed plate


16


. A motor


68


and shaft


66


arrangement may be used. See FIG.


6


. Other means for rotating the trommel


10


, such as belts or external ring gears (not shown) may also be employed.




It should be appreciated that the distal ends


46


of the vibrating rods


42


are unconstrained and are free to float and oscillate within and about the first scallops


38


and the inner race


36


. For emphasis, the distal ends


46


are shown spaced away from the first scallops


38


. However, the distal ends


46


may be spaced away, resting within the first scallops


38


or in a varied alternating relationship with the first scallops


38


. The critical consideration is that the free distal ends


46


of the rods


42


are permitted to float or move within or without the first scallops


38


. As the trommel


10


rotates and solids of varying size, shape and hardness tumble within the classifying section


44


, the spacing between the vibrating rods


42


themselves and the supporting rods


28


is constantly changing. This continuous movement classifies the articles while simultaneously reducing clogging.




By partially embedding the supporting rods


28


and the vibrating rods


42


into the inner race


36


of the support ring


32


little or no obstructions are presented to the larger objects entering into the discharge zone


34


. The low profile of these components permits a free flowing flow path so the objects can easily cascade over the rod support ring


32


into the disclosure with reduced wear and tear.




By anchoring the proximal ends


48


of the vibrating rods


42


while letting the distal ends


46


float, the vibrating rods


42


will continuously flex like tuning forks while constantly altering the spaced relationship between themselves and their neighboring supporting rods


28


within a specified range thusly allowing preselected maximum sizes of objects to fall between the spacing of the rods


28


and


42


.




The quantities of supporting rods


28


and the vibrating rods


42


and their physical relationships may be varied as necessary. Moreover, repeated or random combinations of the rods


28


and


42


may be used. In the non-limiting successful prototype trommel


10


depicted in the figures, the trommel


10


is 28 inches (71.1 cm) long and 14 inches (35.6 cm) in diameter. The discharge zone


34


is 6 inches (15.2 cm) long The rods


28


and


42


are 0.5 inches (1.3 cm) in diameter, 1 inch (2.5 cm) apart and 15 ° offset from one another. The inner diameter of the rod support ring


32


is 11.47 inches (29.1 cm). The opening


26


is 5.75 inches (74.6 cm) in diameter. The first scallops


38


have a 0.25 inch (0.64) cm) radius cut whereas the second scallops


40


have a 0.375 (0.96 cm) radius cut so as to allow a 0.125 inch (0.32 cm) float tolerance.




By selectively configuring the spacing and number of rods


28


and


42


and the size of the classifying and discharge zones


44


and


34


, the trommel


10


may be scaled to classify objects into various size fractions with relatively close tolerances.




As the feed is introduced into the opening


26


, the tumbling action along with the infinite vibratory action of the floating vibrating rods


42


will cause the smaller objects in the classifying zone


44


to fall between the rods whereas the larger pieces will cascade over the unobstructive inner scalloped race


36


into the discharge zone


34


.




Turning to

FIG. 5

, there is shown an alternative rod support ring


32


A. It is lower cost embodiment in that there are no scallops


38


and/or


40


. Machining costs for the scalloping of the ring


32


A are eliminated. The distal ends


46


of the vibrating rods


42


are still free to float since they simply rest on the inner ring surface


36


. The supporting rods


28


are affixed, preferably by welding, to the inner surface of the rod support ring


32


A.




As in the case of the rod support ring


32


, both sets of the rods


28


and


42


present, in alternative rod support ring


32


A, a free flowing unobstructed path for the objects to cascade into the discharge zone


34


.




The design proposed in U.S. Pat. No. 883,974 to Roughedge presents several mechanical disadvantages. In a test prototype, using various sized pellets, and having dimensions similar to those of the trommel


10


above, it was determined the corresponding rod support ring (tail ring K


1


) creates a physical dam (“tire-like hoops “B


4


and “B


5


”) that the pellets must negotiate up and over. This impedes pellet flow and engenders eventual erosion from the particles' continuous physical impacts. The present trommel


10


, however, projects a relatively smooth flow path for the objects over the inner race


36


since all of the rods


28


and


42


are at least partially embedded in the scallops


38


and


40


. Or, in the alternative, adjacent to the inner race


36


as shown in FIG.


5


.




Moreover, since US '974's bars B


2


are free to move and turn in the oblong openings 3 at both ends, the open longitudinal space that the smaller pellets pass through is not equal when the unit turns. This produces a poor size fraction distribution because these bars are forced to the side during operation causing alternating wide and narrow gaps.




In tests of the US '974 design, the maximum feed rate attained was 52.5 tonnes (52,500 kg) per hour but virtually all the pellets passed through the bars and only 0.15% of the pellets discharged into the oversized fraction. This clearly is not a desirable amount with the present invention where 10% oversized fractions are expected.




Finally, the present invention enables more control of the pellet size fractions because the multiple vibratory bars


42


flex at one end with minimal radial motion to prevent plugging. There is also less physical wear on the trommel


10


.





FIG. 6

demonstrates a non-limiting use example for the trommel


10


. The trommel


10


may be mounted within the flow path of materials to be segregated by size.




In the embodiment shown, the canted trommel


10


is disposed in a transition zone between a bucket elevator and a segregator.




The articles or elephants are dropped into an elbow


52


having a by-pass gate


54


driven by an actuator


56


. In order to slow down and disrupt the momentum of the flow of the elephants to the trommel


10


, a chain


58


hangs from the end of the elbow


52


within the trommel


10


just after the opening


26


.




The trommel


10


is housed within a segregator


70


. An internal divider


60


essentially collinear with the rod support ring


32


, captures the smaller fractions falling out of the trommel


10


from the classifying zone


44


into funnel


62


. The larger pieces pass through the discharge zone


34


into the oversize discharge


64


.




The drive motor


68


rotates the trommel


10


by virtue of the shaft


66


affixed to the drive hole


22


.




In tests, the trommel


10


was fed with bed pellets that discharge from a tote bin into a small funnel connected to a 5 inch (12.7 cm) schedule 40 pipe and 90 degree elbow


52


. The elbow


52


extends into the trommel


10


about 5 inches (12.7 cm). Half of the diameter of this pipe was cut away and a circular plate was welded to the end. The elbow


52


discharge area was 29 cubic inches (4.75.2 cm


3


). The chain


58


hangs in front of the cut away pipe.




The maximum feed rate attained was 75-82 tonnes (75,000-82,000 kg) per hour with bed pellets and additions of various size chunks (about 10 per test). This flow rate did not change when the trommel


10


was not rotating. Initially, tests were conducted at 18 RPM at a canted trommel


10


slope of 1.1 degrees. Under these conditions 0.1% of the bed pellets were contained in the oversize fraction due to pellet momentum and deflection from the rods


42


. On occasion some chunks ¾ by 2 by 2 inches (1.9×5.1×5.1 cm) passed through the 1 inch (2.54 cm) spacing into the undersize fraction. When the rate was lowered to 5 rpm, only 0.01% of bed pellets were contained in the oversize fraction. All large chunks and pellets were removed including the largest chunk at 2 by 3 by 5 inches (5.1×7.62×12.7 cm). No plugging occurred.




Additional successful tests using other fractions resulted in flow rates in excess of 100 tonnes (100 kg) per hour. It was determined that an elbow


52


having a 45° angle orientation from the vertical (as opposed to the 90° angle orientation depicted) permitted slightly higher flow rates.




The trommel


10


may be operated solo, that is, by itself where essentially two different sized fraction ranges will be culled from a components stream. Alternatively, a plurality of variously sized ganged trommels


10


may be operated in tandem either nested within one another and/or daisy chained in sequential fashion to cull a plurality of sized fraction ranges.




For example, in

FIG. 7

, a first trommel


110


is nested within a second trommel


112


of larger diameter and rotated by a common drive (not shown). A number of support rods


114


are shared. For simplicity, most rods and components are not shown. The gaps between the various rods of the trommel


114


are greater than the gaps between the rods in the trommel


112


. In this configuration, the objects are fed through feed plate


116


. Fine particles will exit the nested trommels


110


/


112


at location A. Middle sized particles will exit at location B and course particles will emerge at location C.




Alternatively,

FIG. 8

depicts the trommels in a sequential configuration. Smaller diametered trommel


118


precedes larger trommel


120


. Again components may be shared as in the nested configuration of

FIG. 7

or they may be independent. In this sequential example, the gaps of the rods in the trommel


118


are less than the gaps of the rods in the trommel


120


. As the trommels


119


/


120


are rotated objects are fed through the feed plate


122


. Fine particles are discharged in zone D. Middle particles are discharged from zone E and course particles emerge from zone F.




The trommel easily lends itself to numerous configurations, combinations, and sizes. If more than one trommel


10


is desired, the trommels may be connected together or be independent of one another. Moreover, the rotation of the trommels may be modulated as needed. One may rotate clockwise whereas a companion trommel may rotate counterclockwise.




By employing a myriad number of ganged trommels


10


, a multiple of classified objects and articles may be expediously culled in a single pass.




While in accordance with the provisions of the statute, there are illustrated and described herein specific embodiments of the invention, those skilled in the art will understand that changes may be made in the form of the invention covered by the claims and that certain features of the invention may sometimes be used to advantage without a corresponding use of the other features.



Claims
  • 1. A trommel for classifying objects, the trommel comprising a distal drive plate and an opposed proximal feed plate, a first plurality of first spaced longitudinal members extending between the distal drive plate and the proximal feed plate and forming an open cylinder, a member support ring disposed within the open cylinder, the member support ring having an interior periphery, a second plurality of second spaced longitudinal members having distal ends and proximal ends extending between the member support ring and the proximal feed plate respectively, the proximal ends of the second spaced longitudinal members in fixed contact with the proximal feed plate and the distal ends of the second spaced longitudinal members in a free, unattached, and unrestrained floating relationship with the inner periphery of the member support ring so as to move in essentially infinite degrees of freedom, the proximal feed plate and the member support ring forming a classifying zone therebetween, and the member support ring and the distal drive plate forming a discharge zone therebetween.
  • 2. The trommel according to claim 1 wherein the interior periphery of the member support ring includes a plurality of scallops.
  • 3. The trommel according to claim 2 including first and second scallops.
  • 4. The trommel according to claim 2 wherein the first and second spaced longitudinal members are at least partially circumscribed by their corresponding scallops.
  • 5. The trommel according to claim 4 wherein the first spaced longitudinal members are affixed to their corresponding scallops.
  • 6. The trommel according to claim 4 wherein the second spaced longitudinal members float within their corresponding scallops.
  • 7. The trommel according to claim 1 wherein the first spaced longitudinal members are affixed to the interior periphery of the member support ring.
  • 8. The trommel according to claim 1 wherein the second spaced longitudinal members are adjacent to the interior periphery of the member support ring.
  • 9. The trommel according to claim 1 wherein the feed plate includes a central opening.
  • 10. The trommel according to claim 1 wherein the first spaced longitudinal members are attached to the distal drive plate and the proximal feed plate, and the proximal ends of the second spaced longitudinal members are attached to the proximal feed plate.
  • 11. The trommel according to claim 1 including means for rotating the trommel.
  • 12. The trommel according to claim 1 including an object feeder communicating with the feed plate.
  • 13. The trommel according to claim 1 wherein the trommel is disposed within a segregator.
  • 14. The trommel according to claim 1 wherein the distal ends of the second spaced longitudinal members are adapted to flex and oscillate vis-à-vis themselves, the first spaced longitudinal members and the inner periphery of the member support ring.
  • 15. The trommel according to claim 1 including a repeating pattern of first spaced longitudinal members and second spaced longitudinal members.
  • 16. The trommel according to claim 1 wherein the first spaced longitudinal members, and the second spaced longitudinal members are disposed adjacent to the inner periphery of the member support ring thereby creating an unencumbered object flow path between the classifying zone and the discharge zone.
  • 17. The trommel according to claim 1 wherein at least a first trommel is nested within at least a second trommel.
  • 18. The trommel according to claim 1 wherein at least a first trommel sequentially follows at least a second trommel.
US Referenced Citations (13)
Number Name Date Kind
385071 Roberts Jun 1888 A
546447 Grugin Sep 1895 A
883974 Roughsedge Apr 1908 A
1343292 Turner Jun 1920 A
2984351 Van Slyck et al. May 1961 A
3055500 Aubert-Maguero Sep 1962 A
3241667 Grosbety Mar 1966 A
3805952 Pleus Apr 1974 A
4049124 Coppolani et al. Sep 1977 A
5165548 Dumler et al. Nov 1992 A
5332103 Zittel Jul 1994 A
5620101 Andela et al. Apr 1997 A
6360894 Devlin et al. Mar 2002 B1
Foreign Referenced Citations (3)
Number Date Country
0265421 Oct 1987 EP
1449000 Jun 1965 FR
1238808 Dec 1984 RU