Boring Machine

boring machine

Machine tool for producing smooth and accurate holes in a workpiece by enlarging existing holes with a cutting tool, which may bear a single tip of steel, cemented carbide, or diamond or may be a small grinding wheel. The hole's diameter is controlled by adjusting the boring head. Bored holes are more accurate in roundness, concentricity, and parallelism than drilled holes. Boring machines used in toolmaking shops have a vertical spindle and a work-holding table that moves horizontally in two perpendicular directions so that holes can be accurately spaced. In mass-production plants, boring machines with multiple spindles are common. See also drill; drill press; lathe.

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boring machine [′bȯr·iŋ mə′shēn]

(mechanical engineering)

A machine tool designed to machine internal work such as cylinders, holes in castings, and dies; types are horizontal, vertical, jig, and single.

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Boring Machine 

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