Grading technique esp. for table tennis balls - is by vibration spherical object on conical support seat by periodic air flow

摘要

The method is for positioning a spherical body, e.g. a table tennis ball, in a desired position with its centre of gravity perpendicularly beneath the geometric centre of its surface enables the body to oscillate about the position by temporarily raising it from its support. The body is placed in a support (3) with an upward opening, approximately conical support surface (5) with a vertical axis. The body floats and vibrates freely in the support on a fear of air periodically introduced between the support and the body, and is then held in the device desired position by suction. The air inlet is via a square pulse generator (7). The support is adjacent to an inclined plane.