| 摘要 |
<p>A method, machine tool (Fig. 1) and boring bar (12) for machining bores in a series of concentric journals (14) for a camshaft in a cylinder head or block of an engine. The boring bar (12) has an elongate and cylindrical body (72) with a single cutting insert (80) at one end for machining all of the journals (14) one at a time and a plurality of circumferentially spaced and longitudinally extending bearing pads (76) on the body which, when the insert is machining one journal, are received in the previously machined journals to radially constrain and support the boring bar (12). The other end of the bar is received in a chuck (38) or drive spindle of the machine tool which rotates and advances the boring bar (12) through the journals (14) to machine them. Each workpiece (16) is located and clamped in the machine tool (10) with its series of journals (14) to be machined substantially concentric with the axis of rotation of the insert (80) of the boring bar (12). The machine tool alternately rapidly advances and then slowly in-feeds the boring bar (12) through each of the journals at the desired feed rate to machine it. After all the journals (14) are machined, the boring bar (12) is rapidly retracted and withdrawn from the workpiece (16). <IMAGE></p> |
