Dispensing – Agitator followed by discharge assistant and/or... – All rotary
Reexamination Certificate
1999-06-24
2001-05-29
Shaver, Kevin (Department: 3754)
Dispensing
Agitator followed by discharge assistant and/or...
All rotary
C239S339000
Reexamination Certificate
active
06237815
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a dispensing device for pourable, especially powdery material. The dispensing device has a charging chute, a vertical filling pipe adjoining the lower end of the charging chute, and a closing cone arranged at the lower end of the filling pipe. The closing cone is displaceable in the longitudinal direction of the filling pipe by a shaft. The closing cone, in its open position, provides an annular gap at the lower end of the filling pipe. The closing cone, in its closed position, rests against an annular face of the lower end of the filling pipe.
When filling bags with pourable material, it is desirable, on the one hand, to fill the bags quickly in order to increase the capacity of the filling plant. On the other hand, it is necessary to ensure accurate dispensing. Accuracy is important since fill quantities below the nominal value are not permissible and fill quantities above the nominal value are uneconomical. The two requirements, a rapid filling operation, on the one hand, and accurate dispensing, on the other hand, are incompatible with one another. This is due to the fact that rapid filling requires large quantity flows and accurate dispensing utilizes small quantity flows to achieve satisfactory results.
Therefore, according to the state of the art, bags are rapidly filled with large quantity flows, up to a certain level, 90 to 95%, of the nominal quantity. Subsequently, a small quantity flow enters the bags to ensure an accurate filling level which is only a few percentage points in excess of the nominal quantity of 100%.
To achieve the above results, it is possible, in addition to a first filling device for dispensing an approximate quantity, to use a dispensing device which can only release a fine flow of material for fine dispensing. Alternatively, a dispensing device with a filling device for dispensing approximate quantities which allows the setting of differently sized apertures for approximate and precision filling purposes can be used.
One problem in connection with fine dispensing is that powdery materials have a tendency to form bridges in narrow exit apertures. The bridges can prevent the flow of material even in the case of high material loads. Especially, if the material has a sticky consistency which may occur in the food industry with material such as cocoa powder, milk powder or the like, it is practically impossible to have reliable flow conditions in a free flow from a narrow aperture fine dispensing device.
SUMMARY OF THE INVENTION
Thus, it is an object of the present invention to provide a dispensing device which is capable of adding badly flowing materials in a fine flow for fine dispensing purposes. The objective is achieved by a dispensing device with a closing cone. The closing cone, on an upwardly pointing conical face, includes blades with a gradient. In order to convey material through the annular gap by the blades, the closing cone is rotatingly drivable by the shaft.
By setting very narrow annular gaps, the closing cone blades enable the flow of very small quantities of material for fine dispensing purposes. The rotating blades reliably ensure an interference-free flow out of the annular gap. By conveying the material directly in the annular gap, it is possible to avoid the risk of compacting the material before it reaches the annular gap and thus reduces the possibility of the subsequent non-uniform exit of lumps or broken-off quantities of material. In particular, it is possible, optionally by controlling the driving speed of the closing cone during the fine dispensing process, to reduce the flow of material when the nominal filling level is approached. However, as a rule, the closing cone with the blades is rotatingly driven at a constant speed. As soon as the nominal filling level has been reached, the closing cone is immediately closed against the annular edge or annular face in order to interrupt the flow of fine-dispensed material.
According to a first embodiment of the inventive device, a device is provided which is used exclusively for fine dispensing. The device operates independently of a system for approximate filling. Thus, it is possible to use a device with a relatively short filling pipe. This is due to the fact that the bag to be attached is already largely filled when, coming from the approximate filling station, it is pulled over the filling pipe in the dispensing station. A dispensing device of this type, for fine dispensing purposes, needs to be adjustable between a closed position and an open position with a relatively small annular gap, and with the closing cone being driven simultaneously.
According to a second embodiment, a dispensing device is combined with the actual filling device for approximate filling. For such applications, the length of the filling pipe extends down to the bottom of the empty bag which is pulled over the filling pipe. During the filling operation, the bag is lowered, so that the end of the filling pipe is always slightly above the filling level in the bag. For this purpose, it is necessary that, in addition to the closed position, the closing cone comprises a first open position with a large annular gap, to achieve approximate filling level, and a second open position with a small annular gap for carrying out the fine dispensing operation.
In the case of easily flowing materials, i.e. grainy or granular material, the material can flow through the large annular gap in the first open position entirely as a result of the deadweight of the material. Displacement by the blades is only necessary when the annular gap is reduced in size for fine dispensing purposes. If the above-mentioned, badly flowing or sticky material has to be dispensed, in order to avoid interference especially bridge formation in the longer filling pipe, a spiral or worm is provided which is driven at least during the approximate filling process. Here, the closing cone is set to the large annular gap. The spiral or worm can be connected to a hollow shaft which receives the shaft to drive the closing cone. The spiral or worm is driven independently by a second driving motor. During the fine dispensing process, as soon as the closing cone is returned into the small annular gap position, the drive for the spiral or worm is preferably stopped.
In accordance with the invention, the blades are arranged on the upper conical face of the closing cone. In a first preferred embodiment, the downwardly continuing conical face simultaneously constitutes the sealing face which, by raising the closing cone, rests against a lower annular edge of the filling pipe. The closing cone can be lowered down to a point at which the cross-sectional face of the annular gap approximately corresponds to the cross-sectional face of the filling pipe.
In a second possible embodiment, the closing cone includes a second conical counter face on the lower side. The second conical counter face forms the closing face and which, in a lowest position, rests against an internally conical counter face which reduces the free cross-section of the filling pipe. The latter embodiment is more suitable for those devices which are designed entirely for fine dispensing purposes and not for approximate filling purposes. This is because the maximum size of the annular gap is limited in this embodiment.
The closing cone is preferably set such that the shaft for the closing cone, which shaft is firmly connected to the driving motor, is moved together with the driving motor relative to the frame and the charging chute. If an open position with a large annular gap and a dispensing position with a small annular gap have to be set, they are preferably set by a first, firmly arranged setting cylinder. The first cylinder effects the travel between the open position, with the large annular gap, and the dispensing position, with the small annular gap. At least one second setting cylinder, which is moved by the first setting cylinder, causes the sealing cone to a stop against the annular edge or annular face to provide a closed position.
Bui Thach H
Chronos Richardson GmbH
Harness & Dickey & Pierce P.L.C.
Shaver Kevin
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