Device for accurate measurement of the shape of a substantially cylindrical surface

Claim 1

A device for measuring the precise shape of a substantially cylindrical surface comprising a plurality of feeler arms connected to a central frame and disposed at uniform angular intervals around said frame and electrical detectors for measuring the position of the free end of each feeler arm as well as means for maintaining each arm in contact with the cylindrical surface to be measured, means of electromagnetic type for placing said feeler arms in a withdrawn position and means for displacing all the feeler arms together in a common movement relative to said surface, wherein the detectors for measuring the position of each feeler arm end are electrical means for taking differential measurements of the positions of said feeler arm ends, these electrical means being connected to means for multiplexing and modulating signals delivered by the electrical means for taking differential measurements, said mutiplexing and modulating means being coupled with means for demodulating the modulated signals which are connected to recording means through a discriminator.

Claim 2

A device for measuring the precise shape of a substantially cylindrical surface comprising a plurality of feeler arms connected to a central frame and disposed at uniform angular intervals around said frame and electrical detectors for measuring the position of the free end of each feeler arm as well as means for maintaining each arm in contact with the cylindrical surface to be measured, means of electromagnetic type for placing said feeler arms in a withdrawn position and means for displacing all the feeler arms together in a common movement relative to said surface, wherein the detectors for measuring the position of each feeler arm end are electrical means for taking differential measurements of the positions of said feeler arm ends, these electrical means being connected to means for multiplexing and modulating signals delivered by the electrical means for taking differential measurements, said mutiplexing and modulating means being coupled with means for demodulating the modulated signals which are connected to recording means through a discriminator.

Claim 9

A device for measuring the precise shape of a substantially cylindrical surface comprising a plurality of feeler arms, each connected by a pivot to a central frame and all disposed at uniform angular intervals around said frame and electrical detectors for measuring the position of the free end of each feeler arm as well as means for maintaining each arm in contact with the cylindrical surface to be measured, wherein said detectors are secured to the frame, wherein electrical means are provided for multiplexing signals delivered by said detectors, wherein also the extremity of each feeler arm which is opposite to the tip which is in contact with the cylindrical surface is arranged so as to actuate a rod provided with a ferro-magnetic portion and slidably mounted within a winding constituting one of N secondary windings of a transformer for providing at the terminals of said secondary windings, N voltages developed thereacross, the common primary circuit of said transformer being formed by a single winding which surrounds the N secondary windings, said primary circuit being supplied with alternating current from a source of alternating current of constant amplitude, the association of a rod and a winding being such as to constitute a detector, said multiplexing means being provided with means for sequentially transmitting the N voltages developed across the terminals of the N secondary windings in modulated form to means for reconstituting the impression of the said surface from said N voltages by means of N points, having recording means provided with a visual display device, one coordinate of each point on said visual display device being a linear function of the voltage developed on the terminal of the corresponding secondary winding.

Claim 10

A device for measuring the precise shape of a substantially cylindrical surface comprising a plurality of feeler arms, each connected by a pivot to a central frame and all disposed at uniform angular intervals around said frame and electrical detectors for measuring the position of the free end of each feeler arm as well as means for maintaining each arm in contact with the cylindrical surface to be measured, wherein said detectors are secured to the frame, wherein electrical means are provided for multiplexing signals delivered by said detectors, wherein also the extremity of each feeler arm which is opposite to the tip which is in contact with the cylindrical surface is arranged so as to actuate a rod provided with a ferro-magnetic portion and slidably mounted within a winding constituting one of N secondary windings of a transformer for providing at the terminals of said secondary windings, N voltages developed thereacross, the common primary circuit of said transformer being formed by a single winding which surrounds the N secondary windings, said primary circuit being supplied with alternating current from a source of alternating current of constant amplitude, the association of a rod and a winding being such as to constitute a detector, said multiplexing means being provided with means for sequentially transmitting the N voltages developed across the terminals of the N secondary windings in modulated form to means for reconstituting the impression of the said surface from said N voltages by means of N points, having recording means provided with a visual display device, one coordinate of each point on said visual display device being a linear function of the voltage developed on the terminal of the corresponding secondary winding.