Search in the document preview
DRILL MACHINE A machine for making holes with removal of chips. Drilling machines are used for drilling, boring, countersinking, reaming, and tapping. Several types are used in metalworking: vertical drilling machines, horizontal drilling machines, center-drilling machines, gang drilling machines, multiple-spindle drilling machines, and special-purpose drilling machines. Vertical drilling machines are the most widely used in metalworking. They are used to make holes in relatively small work-pieces in individual and small-lot production; they are also used in maintenance shops. The tool, such as a drill, countersink, or reamer, is fastened on a vertical spindle, and the work-piece is secured on the table of the machine. The axes of the tool and the hole to be drilled are aligned by moving the workpiece. Programmed control is also used to orient the workpiece and to automate the operation. Bench-mounted machines, usually of the single-spindle type, are used to make holes up to 12 mm in diameter, for instance, in instrument- making. Heavy and large workpieces and workpieces with holes located along a curved edge are worked on radial drilling machines. Here the axes of the tool and the hole to be drilled are aligned by moving the spindle relative to the stationary work-piece. Horizontal drilling machines are usually used to make deep holes, for instance, in axles, shafts, and gun barrels for firearms and artillery pieces. Center-drilling machines are used to drill centers in the ends of blanks. They are sometimes equipped with supports that can cut off the blank before centering, and in such cases they are called center-drilling machines. Gang drilling machines with more than one drill head are used to produce several holes at one time. Multiple-spindle drilling machines feature automation of the work process. Such machines can be assembled from several standardized, self-contained heads with electric motors and reduction gears that rotate the spindle and feed the head. There are one-, two-, and three-sided multiple-spindle drilling machines with vertical, horizontal, and inclined spindles for drilling and tapping. Several dozen such spindles may be mounted on a single machine. Special-purpose drilling machines, on which a limited range of operations is performed, are equipped with various automated devices. Multiple operations on workpieces are performed by various combination machines. These include one- and two-sided jig boring machines, drilling-tapping machines (usually gang drilling machines with reversible thread-cutting spindles), milling-type drilling machines and drilling- mortising machines used mainly for woodworking, and automatic drilling machines.