a metal-cutting machine for finishing holes, planes, and slots with a highly precise location of centers or surfaces without the use of special attachments for tool alignment.
Jig-boring machines are used for boring, drilling, counter-sinking, reaming, milling, and other types of finishing in individual and small-scale production during the manufacture of cutting and measuring tools, jigs, dies, and key components of machines and instruments. Devices with stable and adjustable end gauges and indicator sensing units are used on jig-boring machines for precise measurements; also used are lead screws with dials and a vernier, which are equipped with error-elimination compensators, and graduated shafts with optical measuring instruments. There are two types of these machine tools: double-sided (gantry) machines with a one-movement table and open-sided (single-sided, overhanging) machines with a two-movement table. In open-sided machines the spindle head moves only vertically; in the double-sided machines it moves horizon-tally along the crosspiece, which can travel in a vertical direction. The manufactured article and the cutting tool on the jig-boring machine are moved relative to one another along orthogonal coordinates (with linear displacement accuracy to 2 microns) and polar coordinates (with angular displacement accuracy to 5 seconds of arc). Sturdy construction is a feature of jig-boring machines, which have smooth drive motions and accurate balancing of fast-rotating parts (to reduce vibration). The machines are installed in insulated areas in which a constant temperature of 20°C is maintained. Jig-boring machines are operated by highly skilled workers.
D. L. IUDIN