Not Applicable
This invention relates to an apparatus for automatically measuring the flow of powder and granular materials through orifices under dynamic conditions. The information produced by these measurements can determine how well a material performs in various processes and equipment such die filling machines, powder injection molds, and pharmaceutical tableting machines.
Many apparatus have been disclosed and produced for measuring how powders and granular materials flow through orifices. These devices range from funnels with a fixed size opening to sample cups with various size orifices in the bottom. The problem with these devices is that the material sample is typically in a static, non-moving condition at the start of the test. This does not simulate many real world applications where the sample powder is moving when it must flow through an opening in a processing machine. This is sometimes solved by manually pouring the material sample into the device at the beginning of the test but this is difficult to control. Also some of these devices use a motorized blade to stir the sample powder to create flow but this does not well simulate powder flowing under gravitational force. Additionally these devices are typically manual devices and results can vary depending on the operator.
A typical funnel device is called the hall funnel and is described in ASTM Standard B213-17. This device consists of a funnel with an opening of 1 millimeter. The opening is blocked by the finger of the operator and sample funnel is filled with a known amount of material sample. The operator removes their finger and measure the time it takes for the sample to flow from the funnel. The device can also be automated for measuring the flow time using a detector for the sample. The problem with this technique is that the powder is not moving at the beginning of the test. This means the test does not simulate how a sample moves through the opening when it is already moving. Also the measurement recorded is time in seconds and not the amount of material that has flowed through the funnel.
Another funnel device is called the Carnet funnel and is described in ASTM B964-16. This device consists of a funnel with an opening of 5 millimeters. The opening is blocked by the finger of the operator and sample funnel is filled with a known amount of material sample. The operator removes their finger and measure the time it takes for the sample to flow from the funnel. The device can also be automated for measuring the flow time using a detector for the sample. The problem with this technique is that the powder is not moving at the beginning of the test. This means the test does not simulate how a sample moves through the opening when it is already moving. The sample can be poured into the funnel manually to attempt to simulate dynamic sample flow conditions but this is difficult to control and the powder is only moving as it is poured into the funnel. Also the measurement recorded is time in seconds and not the amount of material that has flowed through the funnel.
Another device for testing powder flow properties is described in the paper Intrinsic flowability: A new technology for powder-flowability classification by Alberto Gioia in Pharmaceutical Technology, February 1980. This device consists of a sample cylinder to which a disc with a hole is attached. The hole is blocked and the cylinder is filled with a material sample. The hole is then unblocked and the sample material is allowed to flow through the hole. The test is repeated with discs with smaller and smaller holes until the powder stops flowing and the maximum hole size that allows flow is recorded. The problem with this test is that is does not simulate dynamic powder flow conditions but only static conditions where the powder transitions from not moving to moving.
After designing several powder flow testers including apparatus described in U.S. Pat. Nos. 8,438,914 and 8,335,343, the inventors of the present invention determined that industry and academia needed an apparatus to measure how powders and granular materials flow through orifices under dynamic flow conditions and under a range of flow speeds. This would allow researchers to simulate powder flow behavior in many industrial material handling machines.
The invention consists of a container for receiving a material sample to be investigated with one or more orifices, a means of moving the container so the material sample moves and can flow through the orifices in the container, and a means of measuring the amount of material flowing through the orifices. The amount and rate of material flowing through the orifices is a measure of the flowability of the material sample.
The preferred embodiment of the invention is shown in
Additional embodiments would consist of a sample container that is not cylindrical but rectangular, pyramidal, or funnel shaped.