Pipe internal grooving using closed magnetic field system: A novel method

Abstract

The present work proposes an innovative method to form microgrooves on a tube's internal surface through new machining based on the principle of the closed magnetic circuit. A newly designed machine with a magnetic grooving tool was fabricated. The tool consists of a pair of magnets positioned in the pipe to be pulled by another pairing magnet set at the pipe's external side, arranged in sequence of N−S−N−S direction so that it creates a closed magnetic field that has a greater pulling force. By controlling the magnet pair at the pipe's external side in the linear and rotational direction, the magnetic grooving tool is moved in both directions and simultaneously pulled towards the pipe surface to form the microgrooves. The experiment was carried out by adjusting the magnet's size combination and its distance to vary the magnetic strengths. The grooving dimension was examined by using an optical microscope and analysed using a 3‐dimensional laser profilometer surface analyser. With N52 class Nd2Fe12B neodymium (40×10×10 mm3), the maximum groove depth of 75.51 μm was recorded and the minimum depth of 2.33 μm was recorded by using magnet size 10×10×10 mm3. The method is capable to produce microgrooves on the copper pipe's internal surface.