Dispensing – With casing or support – Bracket or suspension supported
Reexamination Certificate
1999-02-10
2003-05-27
Kim, Christopher (Department: 3752)
Dispensing
With casing or support
Bracket or suspension supported
C222S198000, C222S236000, C222S413000
Reexamination Certificate
active
06568567
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to bulk material handling systems and, more particularly, such systems having a static container and means to move material from such container.
BACKGROUND OF THE INVENTION
Bulk-solid metering systems are used to feed finely divided (powdered or granular) material into processing equipment. The processing equipment fed by the metering system (or plural metering systems) uses the material as the sole constituent or as one of the constituents in the intermediate or final product to be made. For reasons that will become apparent, it is important that a bulk-solid metering system deliver a precisely-measured amount of material for each unit, e.g., minute or hour, of operating time. Sophisticated gravimetric and volumetric measuring systems have been developed to help assure the bulk-solid metering system performs in this way. Examples of bulk-solid metering systems are disclosed in U.S. Pat. Nos. 4,804,111 (Ricciardi et al.); 4,983,090 (Lehmann et al.); 5,201,473 (Pollock); 5,215,228 (Andrews et al.) and 5,301,844 (Ricciardi et al.) while hoppers and mass flow bins which might be used in such systems are disclosed in U.S. Pat. Nos. 4,958,741 (Johanson) and 5,361,945 (Johanson).
As but one example of how bulk-solid metering systems are used, a commercial bakery may employ several bulk-solid metering systems to feed one or more types of flour and other ingredients into a large machine for mixing bread dough. It is not unusual to automate the installation so that the operator can program which metering systems are to be operated and the feed rates therefor in order to make a particular type of bread.
As another example, a manufacturer of pharmaceutical products, e.g., cold tablets, may use plural bulk-solid metering systems to feed active and inert ingredients to a powder mixer. In turn, the powder mixer feeds what might be termed a pelletizing machine, the final output product of which is tablets.
Conventional bulk-solid metering systems are characterized by a support structure to which is secured a cone-like, wide-mouth feed hopper. At what might be termed its lower apex, such hopper has a conveyor embodied as a screw or auger rotating in a duct. The auger feeds the material in the hopper outwardly through the duct and the hopper spout to the processing equipment. The hoppers may be made of rigid or flexible substance and, if made of the latter, the system also includes paddles to agitate the hopper and help assure continuous flow of material in the hopper.
Very commonly, there is an extension hopper mounted to and above the feed hopper. The extension hopper increases the overall hopper capacity and where the hoppers are filled by batch filling from, e.g., an overhead crane, using two hoppers is significantly more efficient.
And while perhaps less common, it is not at all unusual to find a bulk-solid metering system in which the extension hopper is connected by a large tube to a bulk storage silo not unlike those found on farms. The silo holds a very large quantity of the material being metered by the system and is used to periodically “recharge” the hoppers so that the bulk-solid metering system can run continuously for long periods of time.
While these earlier systems have been generally satisfactory for their intended purposes, they are not without disadvantages. Inevitably, repairs or other maintenance must be performed. In a conventional arrangement, the extension hopper must first be detached and lifted away from the system. Then the nozzle leading to the process equipment (such nozzle being connected to the feed hopper spout) is disconnected. Then the feed hopper auger and, depending upon the specific configuration, the auger drive are disconnected. Finally, the feed hopper is detached from and lifted upwardly out of the support structure for service. Disconnection and disassembly time is very substantial; the point, of course, is that during downtime, the user is not being availed of the value of the system.
Another disadvantage of certain known systems is that to a certain degree, the feed hopper is configured with ease of system fabrication and ease of hopper sidewall agitation in mind. These considerations are evidenced by hopper shape which, in horizontal cross-section, is rectangular along substantially the entire hopper height. Fabrication is easy since the feed hopper support frame is, itself, likely to be rectangular. And flat hopper sidewalls are or may be easier to make than curved sidewalls. Further, external agitation paddles work well against flat sidewalls. Considered from an ease-of-fabrication standpoint, a rectangular-section hopper is very easy to “transition” from a wide rectangular mouth to the narrow slot-like opening in which the conveying auger is mounted.
However, rectangular hoppers work somewhat poorly at promoting what is known as “mass flow.” Finely divided material in the hopper tends to “hang up” along the straight-line seams formed at the junction of two contiguous flat sidewalls. This can impair the feed-rate accuracy of the system.
And that is not all. Where a rectangular extension hopper is used with a rectangular feed hopper, the “transition” joint between the two hoppers is difficult to seal. Further, rectangular extension hoppers are susceptible to side wall buckling due to high “hydrostatic” pressure from the finely divided bulk material therein. (The study of the mass flow characteristics of finely divided materials and of hoppers used to hold them is no trivial matter. Numerous, highly complex technical papers have been written on the subject.)
And in the manufacture of certain food and pharmaceutical products, it is highly preferred to have the feed hopper substantially free of material from the previous batch before the next batch is “charged” into such hopper. Some types of food and pharmaceutical materials deteriorate over time; “first in, first out” material management helps avoid incorporating deteriorated material into the product being made.
An improved bulk-solid metering system which addresses disadvantages of earlier systems would be a significant advance in this field of technology.
OBJECTS OF THE INVENTION
An object of the invention is to provide an improved bulk-solid metering system which addresses problems and shortcomings of earlier systems.
Another object of the invention is to provide an improved bulk-solid metering system which simplifies certain aspects of system repair and maintenance.
Another object of the invention is to provide an improved bulk-solid metering system which better promotes mass flow.
Yet another object of the invention is to provide an improved bulk-solid metering system which lends itself well to feed hopper agitation. How these and other objects are accomplished will become apparent from the following descriptions and from the drawings.
SUMMARY OF THE INVENTION
The invention involves a bulk-solid metering system of the type having a support structure and a feed hopper mounted with respect to the structure and having an upper edge. In the improvement, the structure includes an upper member and the upper edge of the feed hopper is below the upper member. The structure defines a lateral opening sized and shaped to permit the feed hopper to be withdrawn laterally through the opening.
A significant advantage of the arrangement is that the feed hopper can be serviced without removing any extension hopper which may be attached thereto. Another advantage is that if the feed hopper needs to be removed, the nozzle between the feed hopper spout and the process equipment being fed by the system need not be moved or, at most, needs only minimal time and effort to disconnect such nozzle from the hopper.
In more specific aspects of the invention, the support structure extends along a substantially vertical axis. The feed hopper includes a spout which extends from the hopper body along a first axis away from the vertical axis. The lateral opening is positioned to permit withdrawal of the feed hopper away from the vertical axis and along a second axis. Most prefer
Ahlmer Peter
Deklotz Joseph E.
Heinrici Harald
McKenzie James J.
Jansson Shupe & Munger Ltd
Kim Christopher
Schenck AccuRate, Inc.
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