GB1251023A - - Google Patents

Abstract

1,251,023. Controlling cutting tool position. NATIONAL RESEARCH DEVELOPMENT CORP. 29 Oct., 1968 [30 Oct., 1967], No. 49262/67. Heading B3T. A lathe comprises a tool and a tool support movable relative to a workpiece and means for adjusting the tool relative to its support, a first gauge for determining the position of the tool tip in relation to the workpiece and a second gauge for determining the position of the tool support in relation to the tool tip, the position of the tool relative to its support being altered if the readings of the gauges vary by more than a predetermined amount which is indicative of tool wear or incorrect setting. In one embodiment a tool slide 6 carrying the tool 3 and its holder 4 is supported on a cross slide 7 both slides being movable relative to each other and to a workpiece 1. The first gauge 11 is mounted in a vertical adjustable air bearing 17 on the cross slide 7 and is located in close proximity to the workpiece surface and adjacent the tip of the tool 3. The second gauge 19 is mounted on the cross slide 7 in close proximity to the tool slide 6, the gauges being of the air operated type whereby changes in air pressure in the gaps between the gauge 11 and the workpiece and gauge 19 and the tool slide respectively due to changes in the size of the air gap is indicated on calibrated pressure dials 14 and 21 respectively. A transducer 31 associated with the crossslide 7 provides signals indicative of the movement of the cross-slide which are fed to a digital read out, subsequent operation being effected to correct the position of the tool in relation to the workpiece in order that the required diameter is machined. In an alternative embodiment the tool support is in the form of a piston and cylinder assembly 33, 34, the piston carrying the tool 3a and the cylinder being mounted on the cross-slide. One of the gauges 11a is attached to the tool mounting i.e. piston-rod 32, for cooperation with the workpiece 1a, the other gauge 47 co-operating with the other end 50 of the piston-rod. In this embodiment the control of the position of the cutting tool is effected automatically in response to the gauge pressure which are interpreted to effect control of hydraulic fluid to the cylinder 34 to extend or retract the tool.