Renishaw Plc

Renishaw Transducer Systems Limited

Andrew M Bailey

Mark A Chapman

Seamus McFadden

Marcus J Eales

Apparatus is provided for mounting a ball bar on a machine such that the ball bar can be rotated through 360.degree. in three orthogonal planes which intersect the center of a single ball (22) to calibrate relative movement between the spindle and a table of machine in all three planes. The apparatus consists of amounting device in the form of a block (10) on the machine table from which extends a rod (18) terminating in a socket (20) for supporting the ball (22). The rod extends from the block at a compound angle of 45.degree. to each of the three planes. The ball supports a socket on one end of a ball bar (34). A second mounting device is provided on the machine spindle in the form of a tool arm (26) from which extends a rod (28) terminating in a socket (30) for supporting a ball on the other end of the ball bar (34). The rod (28) extends at a compound angle of 45.degree. to all three planes. The ball bar is thus able to lie in any one of the three orthogonal planes and to be rotated through 360.degree. in each without fouling the mounting devices. The dimensions of the mounting devices are also arranged to be such that the ball bar does not foul the spindle or the table of the machine when being rotated in the vertical planes.

Ball bar apparatus for calibrating a machine

Mounting device for a telescopic transducer

A ball-bar 26 for calibrating machine tools and coordinate measuring machines comprise a unit 30 containing a displacement transducer 34 for measuring axial displacement of a precision ball 28. The ball 28 is pivotably located on the head or spindle 12 of the machine, which is driven in a circle about a ball 22 mounted on the bed or table 10 of the machine at the other end of the ball-bar in order to perform a calibration. The ball-bar has a modular construction, its various components such as the unit 30, extension bar 40, magnetic sockets 24,29, supporting device 14 and magnetic clamp 16 being connected together via M6 screw-threads, e.g. at 18,42,44. This enables the unit 30 to be connected to the various other components in a variety of configurations, e.g. for use as an electronic dial gauge.

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Schaumburg, IL, United States of America

Andrew M Bailey