Fluent material handling – with receiver or receiver coacting mea – With conveying means to supply successive receivers
Reexamination Certificate
2002-01-24
2004-04-20
Huson, Gregory L. (Department: 3751)
Fluent material handling, with receiver or receiver coacting mea
With conveying means to supply successive receivers
C141S083000, C141S153000, C141S178000, C141S181000, C141S233000, C222S052000, C222S077000, C222S413000
Reexamination Certificate
active
06722403
ABSTRACT:
The present invention relates to powder dispensing mechanisms and more particularly to an automated apparatus for accurately and rapidly dispensing measured quantities of powder to containers in one or more arrays.
Although the present invention has been developed for use in pharmaceutical laboratories to automatically perform accurate and rapid weighing of milligram quantities of resin powder into trays carrying arrays of NanoKans, this apparatus is suitable for many other applications in which precise quantities of powder must be dispensed quickly and efficiently. Thus, while the invention will be described in the context of the pharmaceutical application for purposes of illustration, the invention should not be construed as being limited to that particular environment.
Many pharmaceutical applications require the introduction of relatively small quantities of powders which must be accurately measured by weight. In practice, this has proven extremely difficult to accomplish, particularly if precisely measured quantities of the powder must be dispensed rapidly into large numbers of containers.
The flow characteristics of powders vary widely due to particle size, electrostatic properties, the effects of variations in humidity, the surface properties of the particles and the tendency of the particles to adhere to various surfaces. Many different types of powder dispensers have been utilized, including those employing suction and vibratory type feed mechanisms, as well as single and double screw conveyors with various pitches and configurations. However, for one reason or another, none of these known powder dispensers has proved to be sufficiently accurate and rapid for use under all conditions.
Examples of screw type dispensers are found in U.S. Pat. No. 4,844,296 issued Jul. 4, 1989 to Torahiko et al., entitled “Apparatus and Method for Quantitatively Delivering Food Materials”, in U.S. Pat. No. 4,804,111 issued Feb. 14, 1989 to Ricciardi et al., entitled “Mechanism For Metering Solid Materials Which Flow in a Manner Similar to Liquids”; and in U.S. Pat. No. 5,421,513, issued Jun. 6, 1995 to Gubler, entitled “Conveying Device for Exact Metering, Wherein At Least One Projecting Body is Rotated in an Inner, Disrupted Threaded Groove, and a Use Therefor”. The Gubler patent discloses an approach to the problem of surface adherence which utilizes brushes and a sleeve with inner threaded grooves.
The present invention also employs a screw-type conveyor but differs from the screw conveyors of the prior art where the screw is situated within a rigid enclosure with the edge of the screw blade spaced from the interior surface of the enclosure wall. In the present invention, a vertical screw is situated within a compliant sleeve with the screw blade in direct contact with the interior surface of the sleeve wall, resulting in a positive feed system in which the quantity of powder being dispensed can be very accurately controlled, under all conditions, even when the powder is dispensed rapidly.
This is accomplished by utilizing a section of conventional silicone tubing as the sleeve which surrounds the screw so as to form a confined helical channel within the sleeve along which the powder is moved as the screw is rotated. The inner diameter of the silicone tube is selected to be slightly smaller than the outer diameter of the screw blade such that the edge of the screw blade continuously bears against the interior tube wall causing the wall to deform slightly proximate the area of blade contact. However, the silicone tube surface is smooth and resilient enough not to interfere with the rotation of the screw.
This configuration provides a positive feed and at the same time prevents powder from flowing between the screw blade and sleeve wall, and thus out of the bottom of the tube, when the screw is not rotating, such that the quantity of powder dispensed from the bottom of the sleeve can be accurately controlled. The screw maintains a constant but gentle pressure on the powder when it is rotating, without harming the powder.
The screw dispenser is capable of rapidly depositing powder into a plurality of containers, such as NanoKans, in an array. The container array is situated in a tray which rests on a scale platform. In order to enhance the speed and accuracy of the dispensing process, the rate of screw rotation for each dispensing operation is relatively high during the initial time period, when the bulk of the powder is dispensed. After a given time interval, the rotation rate of the screw is decreased and powder is dispensed more slowly, until the required weight of powder has been dispensed. The scale need be operational only during the latter period because it is only important to monitor the weight of the dispensed powder carefully as it approaches the desired level in order to deactuate the motor which drives the screw at the precise time when the desired weight of powder has been dispensed.
Automation of the dispensing process is achieved by moving the powder dispenser assembly sequentially along positions in a X-Y plane, above the powder receiving containers, and then along the Z plane to insert the assembly into each container. The dispenser assembly is moved stepwise between the dispensing positions to align it with each container in the array by a computer controlled plotter-type mechanism. One way to accomplish this is to modify a conventional Gilson liquid handler by replacing the liquid dispensing probe with the powder dispenser assembly of the present invention. Computer control is employed to cause the powder dispenser assembly to move sequentially through the dispensing positions to align with and be inserted into each of the containers of the array, and for actuating the drive motor for the screw to dispense a measured quantity of powder to each container, in turn.
Preferably, a bifurcated bracket is employed to simultaneously position two separate powder dispenser assemblies. Each assembly fills the containers in one of two separate trays, each tray being independently weighed by separate scales. In this way, two different powders can be dispensed simultaneously or twice as many containers can be filled at a time with the same powder.
It is therefore a prime object of the present invention to provide automated apparatus for rapidly dispensing precisely measured quantities of powder to containers in an array.
It is another object of the present invention to provide a powder dispensing assembly in which a screw is rotatably received within a compliant sleeve with the screw blade in direct contact with the interior surface of the sleeve.
It is another object of the present invention to provide a powder dispensing assembly including a screw controlled to rotate within a compliant sleeve at a relatively high rate during an initial time period and at a slower rate thereafter.
It is another object of the present invention to provide computer controlled apparatus which sequentially moves a powder dispensing assembly to predetermined positions relative to containers in an array.
It is another object of the present invention to provide an automated apparatus for rapidly dispensing precisely measured quantities of the same or different powders into containers in separate container arrays.
In accordance with one aspect of the present invention, a powder dispensing assembly is provided. The assembly includes a powder reservoir with an outlet. A compliant sleeve having an inner surface is situated proximate the reservoir outlet. A rotatable screw with a blade is provided. The screw is received within the sleeve with the blade is in contact with the inner surface of the sleeve. Drive means for rotating the screw relative to the sleeve are provided.
The outer diameter of the screw blade is at least as large, and preferably slightly larger, than the inner diameter of the sleeve. This insures that direct contact is maintained between the screw blade and the sleeve.
The sleeve preferably takes the form of a section of a silicone tube.
The assembly further comprises a rigid tube. One end
Bertok Alexander
Kuspiel Edward Joseph
Ruediger Waldemar
Trpisovsky Carl J.
Zhou Peng
Baxam Deanna L.
Bristol--Myers Squibb Company
deVore Peter
Huson Gregory L.
LandOfFree
Automated apparatus for dispensing measured quantities of... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Automated apparatus for dispensing measured quantities of..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Automated apparatus for dispensing measured quantities of... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3250148