GB2067978A - Slot distributor for a particulate material metering system - Google Patents

Abstract

A distribution member (40) for providing a controllable flow of a particulate material comprises a flat- bottomed member to receive a mound of material which is aerated and fluidized into an uncompacted state and moved in a uniform volumetric flow over a metering edge (54) of a vertical wall portion of the member. The metering edge (54) of the member and the lower edge (56) of an upper annular collar (42) define a substantially continuous slot (58) for passage of the particulate material which fluidize the material. The collar (42) is spaced from member (44) by members (60), (62), and the material is agitated by wires (28), (68). <IMAGE>

Description

SPECIFICATION Slot distributor for a particulate material metering system Technical Field The present invention relates to a system for metering particulate material and in particular to a slot distributor for use in a particulate material metering system.

Background Art The invention relates to particulate material metering, and more particularly, to metering devices and methods wherein the material is fluidized and aerated to an uncompact state prior to volumetric metering to achieve a high degree of accuracy over a wide range of masses.

The apparatus disclosed in U.S. Patent No. 3,804,303, issued April 16, 1974, and U.S.

Patent No. 3,981,417, issued September 21, 1976, both patents having Arthur L. Fassauer as inventor, meet the requirements above. These patents generally described and claimed a system for metering particulate material comprising a storage hopper having a bottom opening therein containing a mass of the particulate material to be metered. A pressure relief plate having a plurality of holes therein is mounted within and closes the bottom opening in the hopper. An upper orbsweep is rotatably mounted above the pressure relief plate and includes an upper orb-sweep wire fixed thereto and extending radially outward adjacent the upper surface of the plate. A conical metering hopper is located below the pressure relief plate for collecting material passing through the holes in the plate.The wall of the metering hopper defines a central feeding opening at the bottom. A distributor ring is located beneath the central feeding opening in the metering hopper.

The distributor ring comprises a circular substantially horizontally disposed particulate material support surface and a cylindrical metering surface extending around and upwardly from the support surface and having a plurality of port holes formed therethrough. A distributor blade is rotatably mounted within the distributor ring and includes at least one arm extending outwardly above the support surface and then upwardly adjacent the metering surface. A lower orb-sweep wire is fixed to the distributor blade and extends up through the central feeding opening and parallel and adjacent to the inner surface of the metering hopper. The distributor blade and the upper orb sweep are linked for conjoint rotation. A collecting hopper is located beneath the distributor ring.The system further includes means for rotating the distributor blade to (a) move the upper orb-sweep wire adjacent the upper surface of the pressure relief plate to fluidize and bottom unload particulate material from the storage hopper through the holes in the pressure relief plate and into the metering hopper, (b) move the lower orbsweep wire adjacent the inner surface of the mettering hopper to fluidize and bottom unload particulate material through the central feeding opening into the distributor ring, and (c) rotate the distributor blade and move a mound of particulate material along the metering surface of the distributor ring to allow a predetermined fraction of the mound to flow, by gravitation action, through the port holes in the metering surface into the collecting hopper.

The port holes used with the system described above and disclosed in the above patents have worked well with most materials, however, problems have arisen with the use of certain materials which may be characterized as nonflowable. Such materials tend to conglomerate and stick together. Examples of such materials are titanium dioxide (Tl02), fiberglass, asbestos and powdered eggs. Such materials tend to clog the port holes, thereby causing some of the material to bypass certain of the port holes and as a result degrade the accuracy of the system.

Therefore, there is a need for a distributor ring or orbital collar for use in a system for metering particulate material which permits accurate metering of certain non-flowable materials which tend to conglomerate and stick together.

Disclosure of the Invention In accordance with the present invention, an improved metering system for particulate materials is provided. The system is of the type having a substantially horizontally disposed particulate material support surface and means for maintaining a generally constant level of particulate material on the support surface. A metering surface extending along and upwardly from the support surface to a metering edge and a distributor blade including portions extending horizontally adjacent to the support surface and upwardly adjacent to the metering surface are also provided. The distributor blade portions further include means which contact the particulate material.The system also having means for moving the distributor blade along the metering surface moving a mound of particulate material radially outward, the material having an upper surface extending at the natural angle of repose of the particulate material through points in the plane of the metering surface which are above the metering edge so that particulate material from the top of the mound flows over the metering edge under the action of gravity. The improvement in the system comprises a distribution member..

The distribution member comprising a flat bottom portion having the substantially horizontally disposed particulate material support surface thereon, and a vertical extending wall portion having the metering surface thereon and extending along and upwardly from the support surface.

In accordance with another aspect of the present invention, a volumetric system for particulate materials is provided. The system comprises a distribution ring member, said ring member having a flat circular bottom portion defining a substantially horizontally disposed particulate material support surface. The system also having means for maintaining a generally constant level of particulate material on the support surface. The distribution ring member further has a cylindrical wall portion extending around and upwardly from the support surface to a metering edge.The system also comprises a distributor blade having at least one arm extending outwardly above the support surface and then upwardly adjacent the cylindrical wall portion with the distributor blade having means that contact the particulate matter and means for rotating the distributor blade and thereby radially moving a mound of particulate material along the cylindrical wall portion so that particulate material from the mound flows from the upper portion of the mound over the metering edge under the action of gravity.

In accordance with yet another aspect of the present invention, a slot distributor for a particulate material metering system is provided.

The slot distributor comprises a distribution member, the distribution member having a flat bottom portion forming a particulate support surface and a vertical extending wall portion extending along and upwardly from the support surface to a metering edge. The slot distributor further comprises a collar member disposed above the distribution member, the lower edge of said collar member and said metering edge forming a substantially continuous slot therebetween. The distribution member and collar member permit a continuous flow of particulate material over the metering edge when the flat bottom portion supports a mound of particulate material characterized by an upper surface extending at the natural angle of respose of the particulate material through said slot.

Brief description of the Drawings The advantages and further aspects of the present invention will be readily appreciated by those of ordinary skill in the art as the same becomes better understood by reference to the following Detailed Description when considered in connection with the accompanying drawings in which: FIGURE 1 is a partial cross-sectional side view of the metering system of the present invention; FIGURE 2 is a top view of the slot distributor for use in the metering system; and FIGURE 3 is a side view of the slot distributor for use in the metering system.

Detailed Description Referring now to the drawings, wherein like reference characters designate like or corresponding parts throughout several views, there is shown in FIGURE 1 a metering system 10.

An outer tubular housing 12 is provided with a hopper 14 for holding material to be metered thereon. A portion of hopper 14 is formed by conical wall 18. Below hopper 14 is a pressure relief plate 20.

Mounted within the portion of hopper 14 without conical wall 18 is a hemispherical upper orb-sweep 22 which is fixed to the end of a centrally extending drive shaft 24. The upper orbsweep 22 includes a threaded axially extending hole which is received on external threads 26 of the centrally extending drive shaft 24. Mounted to the orb-sweep 22 is an upper orb-sweep wire 28 which extends horizontally outward to a point beyond a plurality of holes 30 in pressure relief plate 20.

The hopper 14 is supported by member31 and outer tubular housing 12 through member 32. A material diverter cone 33 is mounted on the lower surface of pressure relief plate 20 as shown. The walls of the material diverter cone 33 extend downwardly to within the walls of a metering hopper 35. A central feed opening 34 is defined with a screed ring 36 extending downwardly and outwardly from its outlet. The various components are held in position by a plurality of cylindrical spacer sections 38.

A slot distributor 40, forming the inventive concept of the present invention, is provided. The slot distributor 40 comprises an upper annular collar 42 and a distributor ring 44 as best shown in FIGURE 3. Upper annular collar 42 has a flange 46 extending horizontally outward therefrom for supporting slot distributor 40 on a spacer section 38.

Distributor ring 44 is disposed below upper annular collar 42 and is generally cylindrical with a flat circular bottom 48 and a vertically extending cylindrical wall 50. The uppermost extent of cylindrical wall 50 forms a metering edge 54. The lower edge 56 of upper annular collar 42 and metering edge 54 define a slot 58 therebetween.

The distributor ring 44 depends from upper annular collar 42 and is attached thereto by three rod members 60, 62 and 64. Each rod member 60,62 and 64 is positioned 1200 from the next adjacent rod member.

The lower surface of the distributor ring 44 includes an annular peripheral ridge 65 against the inside surface of which is mounted a domelike enclosure 67. A motor 52 or other means is mounted within casting 67 to rotate drive shaft 24 in a manner described in the Applicant's prior U.S.

Patent No. 3,804,303, issued April 16, 1 974,'and U.S. Patent No.3,981,417, issued September 21,1976.

The motor output shaft 53 passes through an opening in the bottom of the distributor ring 44 and through a bushing 70 within the ring. A distributor blade 71, having curved outwardly extending arms 72, is attached to a motor output shaft 53. The centrally extending drive shaft 24 is coupled to the output shaft 53 by means of an internally threaded coupling sleeve 66. A lower orb-sweep wire 68 is mounted in a socket formed in the top of the distributor blade 71 and extends up through the central feeding opening 34 in the bottom of the metering hopper 35 and along and adjacent to the inner surface of the metering hopper walls. As seen in FIGURE 1, the outer surface of wall 50 of the distributor ring 44 is spaced from the inner surface of the collecting hopper 74 so that particulate material passing over distributor ring 44 and metering edge 54 will fall into collecting hopper 74.

Referring to FIGURE 1, the system operates as follows. A quantity of the particulate material to be metered is place in the hopper 14. When drive shaft 24 is rotated, orb-sweep 22 is rotated therewith. The orb-sweep wire 28 moves in a circular pattern above the surface of pressure relief plate 20 and meters a small amount of materials through each of the holes 30.

The material trickles down through the pressure relief plate 20 onto the outer surface of the material diverter cone 33 and into the metering hopper 35. The lower orb-sweep wire 68 moves about the inside periphery of the metering hopper so that the material is gently agitated to bottom feed through the opening 34 into the area of the distributor ring 44 within the screed ring 36.

Particulate material is removed from beneath the screed ring 36 by the rotating arms 72 of the distributor blade 71. In general, the arms 72 of the distributor blade aerate and fluidize the particulate material and move uncompacted material over metering edge 54 and into the collecting hopper 74. The material adjacent the metering edge 54 within distributor ring 44 flows by gravitational action over the metering edge 54 and into the collecting hopper 74. The amount of material flowing over a metering edge 54 is determined and limited by the angle of respose of the material.

That is, the depth of the mound of material adjacent metering edge 54 within distributor ring 44 is great enough that the natural angle of repose causes the surface of the mound to extend through slot 58, or, in order words, to a level through points in the plane of the vertically extending cylindrical wall, which are above the metering edge. Thus, a fractional volume of the mound of material, containing a predetermined mass of material, flows by gravitational action from the mound and over metering edge 54. The flow over metering edge 54 is due only to gravity and the particulate material is never "pushed" or forced to move in any direction so that there are no forces which would tend to compact the particles. The material is metered out at a highly accurate, constant mass flow per unit of time.The mass delivered per minute is directly related to the number of distributor blade arms 72 and the number of revolutions per minute of the distributor blade 71.

Further description relating to the function of screed ring 36, distributor blade 71 and electrical control circuitry that may be used in the system which are not relevant to the inventive concept of the present invention are further described in United States patents 3,804,303 issued April 16, 1974 and 3,981,417 issued September 21,1976.

The system described in the above noted United States patents disclose the use of a distributor ring having a flat circular bottom and a vertically extending cylindrical wall. The vertical extending cylindrical wall had a plurality of circular port holes formed therethrough with their lower edges defining the metering edge. While the use of these port holes works well with most materials, problems do arise with the use of certain materials which may be characterized as non-flowable. Such materials tend to conglomerate and stick together. Examples of such materials are titanium dioxide (T102), fiberglass, abestos and powdered eggs. Such materials tend to clog the port holes, thereby causing some of the material to bypass certain of the port holes and thereby degrade the accuracy of the system.

The use of slot distributor 40, described hereinabove, solves this problem by replacing the port holes by a substantially continuous horizontal slot 58. Non-flowable materials such as mentioned above may be metered by a system including a slot distributor 40 as no clogging will take place at the metering edge 54.

The use of slot distributor 40 also has the advantage of reducing the pulsating action of a material flow over discrete metering edges that are formed by the presence of a plurality of port holes, at times numbering 36, in the distributor ring. This permits a more continuous material flow with the flow being more linearly related to the number of distributor blade arms 72 and rotational velocity of distributor blade 71.

In a typical application, the slot 58 will have a dimension of 1 1/4" about its entire extent. An internal diameter of 1 5" may be provided for annular collar 42 and cylindrical wall 50, with flange 46 being 11/8" wide and the slot distributor having a total height of 4 3/4". Rod members 60, 62 and 64 may be formed of 1 1/8tut diameter rods, 3/4" x 4 1/2to x 1/4" bars or any other suitable structure and welded to annular collar 42 and cylindrical wall 50.

It is clear that slot distributor 40 may be employed in any suitable type of material metering system and need not be limited to use with the structure of metering system 10 as shown in FIGURE 1. The principles and operation of slot distributor 40 also may be as effectively employed in any environment where it would prove useful.

Although one particular embodiment of the present invention has been described in the foregoing Detailed Description, it will be understood that the invention is not limited to the embodiments disclosed, but is capable of numerous rearrangements, modifications, and substitution of parts and elements without departing from the spirit of the invention.

Claims (22)

1. An improved metering system for particulate materials of the type having a substantially horizontally disposed particulate material support surface, means for maintaining a generally constant level of particulate material on said support surface, a metering surface extending along and upwardly from the support surface to a metering edge, a distributor blade including portions extending horizontally adjacent to the support surface and upwardly adjacent to the metering surface, said distributor blade portions further including means which contact the particulate material and means for moving the distributor blade along the metering surface to move a mound of particulate material radially outward, said material having an upper surface extending at the natural angle of repose of the particulate material through points in the plane of the metering surface which are above the metering edge so that particulate material from the top of the mound flows over the metering edge under the action of gravity, wherein the improvement comprises: a distribution member comprising a flat bottom portion having said particulate material support surface thereon and a vertical extending wall portion having said metering surface thereon and defining a substantially continuous horizontal metering edge.

2. The improved metering system of Claim 1 wherein the improvement further comprises; a collar member disposed above said distribution member, the lower edge of said collar member and said metering edge forming a substantially continuous slot therebetween.

3. The improved metering system of Claim 2 wherein the improvement further comprises: a plurality of rod members suspending said distribution member from said collar member, said rod members being secured between said distribution member and said collar member at equidistant points along said distribution member and said collar member.

4. The improved metering system of Claim 2 wherein said flat bottom portion of said distribution member is substantially circular and said vertical extending wall portion of said distribution member and said collar member are substantially annular.

5. A volumetric system for particulate materials comprising: a distribution ring member having a flat circular bottom portion defining a substantially horizontally disposed particulate material support surface; means for maintaining a generally constant level of particulate material on said support surface; said distribution ring member further having a cylindrical wall portion extending around and upwardly from the support surface to a substantially continuous horizontal metering edge; a distributor blade having at least one arm extending outwardly above the support surface and adjacent the cylinder wall portion, said distributor blade having means which contact the particulate material; and means for rotating the distributor blade and radially moving a mound of particulate material along the cylindrical wall portion so that particulate material from the mound flows from the upper portion of the mound over said metering edge under the action of gravity.

6. The volumetric system of Claim 5 further comprising an annular collar member disposed above said distribution ring member, the lower edge of said annular collar member and said metering edge forming a substantially continuous slot therebetween.

7. The volumetric system of Claim 6 further comprising a plurality of rod members suspending said distribution ring member from said annular collar member, said rod members being secured between said distribution ring member and said annular collar member.

8. A volumetric metering system for particulate materials as set forth in Claim 5 wherein: the means on the distributor blade include airfoil like leading edges and a flat vertically extending trailing surface to aerate and fluidize particulate material located abdve the support surface as the blade is rotated.

9. A volumetric metering system for particulate material as set forth in Claim 5 wherein each arm of the distributor blade comprises: a circular rod formed to extend outwardly above the support surface, upwardly adjacent the cylindrical wall portion and inwardly above, parallel to, and spaced from the outwardly extending portion thereof.

10. A volumetric metering system for particulate material as set forth in Claim 5 which also includes: means for aerating and fluidizing particulate material to be metered onto the material support surface.

11. A volumetric metering system as set forth in Claim 5 which also includes: means for catching the particulate material flowing over said metering edge.

12. A system for metering particulate material including: means for bottom unloading particulate material from a hopper into a particulate material aeration and fluidization zone; means for aerating and fluidizing the particulate material within the aeration and fluidization zone so that the mass of particulate material per unit of volume is substantially constant throughout the aeration and fluidization zone; means for bottom unloading particulate material out of the aeration and fluidization zone into a metering zone comprising a distribution member, said distribution member comprising a flat bottom portion forming a support surface and a vertical extending wall portion forming a metering surface extending upwardly from the support surface and having a substantially continuous horizontal metering edge at its upwardmost extent at a predetermined height above the support surface;; means for forming a mound of particulate material on the support surface in the metering zone characterized by an upper surface extending at the natural angle of repose of the particulate material through points in the plane of the metering surface which are above the particulate material metering edge; and means for radially moving the mound of particulate material outwardly around the metering surface in the metering zone so that particulate material from the upper portion of the mound continuously flows over the metering edge under the action of gravity.

13. The system of Claim 12 further including: a collar member disposed above said distribution member, the lower edge of said collar member and said metering edge forming a substantially continuous slot therebetween.

14. The system of Claim 12 wherein said flat bottom portion is substantially circular and said vertical extending wall portion is substantially annular.

1 5. The system of Claim 13 further including; a plurality of rod members suspending said distribution member from said collar member, said rod members being secured between said distribution member and said collar member at equidistant points along said distribution member and said collar member.

1 6. The system of Claim 12 further including: means for catching the particulate material flowing over said metering edge in a collection hopper.

1 7. A system for metering particulate material substantially as herein described with reference to the accompanying drawings.

1 8. A slot distributor for a particulate material metering system comprising: a distribution member, said distribution member having a flat bottom portion forming a particulate support surface and a vertical extending wall portion extending along and upwardly from the support surface to a metering edge; a collar member disposed above said distribution member, the lower edge of said collar member and said metering edge forming a substantially continuous slot therebetween; and said distribution member and collar member permitting a continuous flow of particulate material over said metering edge when said flat bottom portion supports a mound of particulate material characterized by an upper surface extending at the natural angle of respose of the particulate material through said slot.

19. The slot distributor of Claim 17 wherein said flat bottom portion is substantially circular and said vertical extending wall portion and said collar member are substantially annular.

20. The slot distributor of Claim 17 further comprising a plurality of rod members suspending said distribution member from said collar member, said rod members being secured between said distribution member and said collar member at equidistant points along said distribution member and said collar member.

21. The slot distributor of Claim 19 wherein three rod members are secured between said distribution member and said collar member 1200 apart.

22. A slot distributor for a particulate material as herein described with reference to the accompanying drawings.