Patent ID: 6501068
Filing Date: 2002-12-31
Classification: B23K

Abstract:
A method of manufacturing grating patterns on the surfaces of grating elements of a torque transducer, the torque transducer comprising a shaft with a longitudinal axis, the shaft comprising first and second substantially rigid torque input members which are connected by a torsionally compliant coupling, the coupling thereby enabling angular deflection of the first torque input member relative to the second torque input member as a function of the magnitude of the torque in the shaft, a first grating element attached to or integral with the first torque input member and a second grating element attached to or integral with the second torque input member, the surfaces of the two grating elements being adjacent and able to relatively displace as a function of torque in the shaft, the method comprising the steps of:a first step of forming an assembly by rotationally and axially fixing the first and second torque input members and respective grating elements to the torsionally compliant coupling; a second step of mounting the assembly in a machine comprising a radiation source arranged to irradiate regions of the adjacent surfaces of the two grating elements whilst a predetermined relative angular displacement between the two torque input members with respect to their zero torque alignment condition is maintained; and a third step of simultaneously irradiating regions of the adjacent surfaces of the two grating elements whilst the predetermined angular displacement between the two torque input members is maintained; thereby generating grating patterns on the surfaces of the two grating elements of the assembly which are precisely mutually aligned for this zero torque alignment condition.