초록 ▼

A novel method and apparatus are provided by the invention for the precision-control of the thickness of thin work pieces under lapping in a lapping machine having an upper and lower lapping surface plates rotatable relative to each other sandwiching the work pieces with continuous supply of a lappi

A novel method and apparatus are provided by the invention for the precision-control of the thickness of thin work pieces under lapping in a lapping machine having an upper and lower lapping surface plates rotatable relative to each other sandwiching the work pieces with continuous supply of a lapping fluid therebetween. In the invention, the upper lapping surface place is provided with an opening in the lapping surface, in which an ultrasonic transducer means is mounted capable of projecting an ultrasonic wave to the work piece and receiving the dual echo waves reflected at the upper and the lower surface of the work piece so as that the delay time of the echo waves is transmitted as electrical signals to a control means of the lapping machine where the signals are computed in terms of the thickness of the work pieces and utilized for controlling the operation of the machine. The space between the ultrasonic transducer means and the work piece is filled with the lapping fluid so that any errors in the propagation of the ultrasonic waves can be minimized.

대표청구항 ▼

A method for lapping a thin work piece in a lapping machine having a lower lapping surface plate with an annular lapping surface and an upper lapping surface plate with an annular lapping surface rotating relative to and substantially in parallel with the lower lapping surface plate with said work p

A method for lapping a thin work piece in a lapping machine having a lower lapping surface plate with an annular lapping surface and an upper lapping surface plate with an annular lapping surface rotating relative to and substantially in parallel with the lower lapping surface plate with said work piece sandwiched therebetween and with a continuous supply of a lapping fluid to the interspace therebetween, which method comprises: (a) projecting an ultrasonic wave substantially perpendicularly to the surface of the work piece through said lapping fluid and said work piece, said wave passing through an opening provided in a portion of the annular lapping surface of the upper lapping surface plate with an ultrasonic transducer means, (b) receiving the echo waves of the ultrasonic wave reflected at the upper and the lower surfaces of the work piece with the ultrasonic transducer means whereby the echo waves are converted into electric signals corresponding thereto, and (c) transmitting the electric signals to a control means for the lapping machine where the electric signals corresponding to the delay time of the echo waves are computed in terms of the thickness of the work piece and utilized for controlling the operation of the lapping machine.