Browse Prior Art Database

Magnetic Torquer

IP.com Disclosure Number: IPCOM000045057D
Original Publication Date: 1983-Jan-01
Included in the Prior Art Database: 2005-Feb-06
Document File: 2 page(s) / 41K

Publishing Venue

IBM

Related People

Wray, TE: AUTHOR

Abstract

The magnetic torquer was designed to provide a stress-free means of attachment to a source of energy which would impart an essentially pure torsional force to a small drill bit. This is accomplished by using epoxy to bond the drill bit into a small hole in a permanent magnet, which then is inserted into an alternating magnetic field which creates the torsional force on the bit. The shank of the bit is held rigidly in a torque-sensing transducer, which serves the dual purpose of holder and measurement device. The end purpose of the mechanism is to provide a way to measure dynamic torsional fracture torques and to determine whether the fracture is brittle or induced by fatigue. Secondarily, the ultimate strength of the drill bit material can be extracted from measured breaking torque.

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Magnetic Torquer

The magnetic torquer was designed to provide a stress-free means of attachment to a source of energy which would impart an essentially pure torsional force to a small drill bit. This is accomplished by using epoxy to bond the drill bit into a small hole in a permanent magnet, which then is inserted into an alternating magnetic field which creates the torsional force on the bit. The shank of the bit is held rigidly in a torque-sensing transducer, which serves the dual purpose of holder and measurement device. The end purpose of the mechanism is to provide a way to measure dynamic torsional fracture torques and to determine whether the fracture is brittle or induced by fatigue. Secondarily, the ultimate strength of the drill bit material can be extracted from measured breaking torque.

Referring to Fig. 1, ramp generator 3 controls the rate at which the output of constant frequency generator 5 increases in magnitude. The output of generator 5 is supplied to a power amplifier 7 driving an electromagnet 9. This creates a linearly increasing AC magnetic field in the magnetic circuit including a magnetizable core 11 which imparts a linearly increasing torsion on a permanent magnet 13, and hence on the drill bit 15 attached to the magnet.

The top crossbar 17 of the assembly serves as a torque transducer and a convenient way to mount and position the drill and permanent magnet in the air gap where the alternating magnetic field exists. The permanent magnet is aligned perpendicularly to the pol...