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boring machine[′bȯr·iŋ mə′shēn]
a metalcutting machine for drilling, countersinking and countersink reaming, reaming, boring, threading, machining cylindrical surfaces and faces, and milling. Universal horizontal boring machines are the most common type. For a number of operations, diamond boring machines and jig-boring machines are used.
Universal horizontal boring machines have a horizontal spindle mounted in a stock that moves up and down along a front support. There are three basic configurations: (1) machines for working small and medium-sized items, with spindle diameters up to 125 mm, a table that moves in two mutually perpendicular directions, and a stationary front support; (2) machines for working medium-sized and large items, with spindle diameters from 100 to 200 mm and a table and front support moving in mutually perpendicular directions; and (3) machines for working particularly large items, with spindle diameters from 125 to 320 mm, without a table, with a front support (column) that moves in one or two directions.
The spindle unit, which gives the machine its broad range of uses, consists of a hollow spindle that carries a faceplate with a cutter (the main motion) and an inner boring spindle driven in the axial direction (the feed motion). The performance abilities of boring machines are greatly increased by using spindle units having separate drives for a faceplate with a radial slide and for the inner spindle. The fitting of various attachments also widens the range of uses, permitting, for example, a combination of several changeover operations into one.
Trends in the development of boring machines include increasing the rigidity and resistance to vibration, reducing friction in moving parts, and using digital display, numerical control, and methods of remote observation and control of the working process, primarily in heavy-duty and special boring machines.
G. A. LEVIT