Northern Research & Engineering Corp.

Melvin Platt

Willem Jansen

Alan R Levine

Brad W Amidon

Pedro H Moura

A centrifugal impeller includes a hub formed about an axis of rotation with a plurality of substantially radially extending blades affixed to the hub, each blade having a suction surface, and a pressure surface formed on the adjacent blade facing the suction surface. The blades have a height being measured in a radial direction from the hub. A portion of the hub, having a hub configuration, extends between the pressure surface and the suction surface. An imaginary plane extending in a direction normal to the axis of rotation is used to define a cross-sectional view of the impeller. A first and a second concentric circle are formed in the plane with the center of the concentric circles being the axis of rotation. The first circle passes through a point on the hub located closest to the axis of rotation. The second circle has a radius greater than the first circle by an amount equal to five percent of the blade height, wherein a portion of the hub extends outside of the second circle. This configuration has, on occasion, improved flow characteristics for centrifugal impellers over impellers having concentric hub configurations.

Arbitrary hub for centrifugal impellers

A computer generated tool path interference check including a method of checking for interference between a workpiece and a cutting tool during the numerical control machining of the workpiece by the cutter tool. Computer simulation is utilized to determine at least a portion of the workpiece that is desired to be checked for possible interference with the path of the cutter tool. The spatial relationship between the workpiece and the cutter tool during the machining are modelled as the relative positioning of the computerized images of the portion of the workpiece and the cutter tool, respectively. The relative positioning of the computerized images of the portion of the workpiece and the cutter tool are observed to check whether an interference will occur between the workpiece and the cutter tool during the machining.

Computer generated tool path interference check method

A method for determining a smooth machining course for a cutting tool during machining of a workpiece. Each possible cutting tool position, with respect to the workpiece, is defined by a separate reference vector. A progression of points are defined as a tool path. A first specified portion of the reference vector will follow the tool path during machining of the workpiece. A series of reference planes are generated, each plane defines a planar set of all possible reference vector positions for each point. An acceptable range from eahc set is established which defines acceptable reference vector positions within each plane for each point. A tool course is generated, which will be followed by a second portion, distant from the first portion, of the reference vector utilizing an algorithm to minimize irregularities of the course, and to contain the course entirely within the acceptable range.

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Holliston, MA, United States of America

Melvin Platt