Drill Presses Unit 38

Drilling Machines Probably first mechanical device developed Principle of rotating tool to make hole One of most common and useful machines in industry Come in several types and sizes From hand-fed to computer-controlled

Drill Press Drilling machine Spindle Work table Turns drill to advance into work (hand or automatically) Work table Holds workpiece rigidly in place as hole drilled Used primarily to produce holes in metal Other operations: tapping, reaming, boring, counterboring, countersinking, spot-facing

Standard Operations Drilling Countersinking Operation of producing hole by removing metal from solid mass using twist drill Countersinking Operation of producing tapered or cone-shaped enlargement to end of hole > Countersinking (Fig. 38-1b) is the operation of producing a tapered or cone-shaped enlargement to the end of a hole. > Reaming (Fig. 38-1c) is the operation of sizing and producing a smooth, round hole from a previously drilled or bored hole with the use of a cutting tool having several cutting edges. > Boring (Fig. 38-1d) is the operation of truing and enlarging a hole by means of a single-point cutting tool, which is usually held in a boring bar. > Spot-facing (Fig. 38-1e) is the operation of smoothing and squaring the surface around a hole to provide a seat for the head of a cap screw or a nut. A boring bar, with a pilot section on the end to fit into the existing hole, is generally fitted with a double-edged cutting tool. The pilot on the bar provides rigidity for the cutting tool and keeps it concentric with the hole. For the spot-facing operation, the work being machined should be securely clamped and the machine set to approximately one-quarter of the drilling speed. > Tapping (Fig. 38-1f) is the operation of cutting internal threads in a hole with a cutting tool called a tap. Special machine or gun taps are used with a tapping attachment when this operation is performed by power in a machine. > Counterboring (Fig. 38-1g) is the operation of enlarging the top of a previously drilled hole to a given depth to provide a square shoulder for the head of a bolt or capscrew. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Standard Operations Reaming Boring Operation of sizing and producing smooth, round hole from previously drilled or bored hole Boring Truing and enlarging hole by means of single-point cutting tool Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Standard Operations Tapping Counterboring Cutting internal threads in hole with cutting tool called tap Counterboring Enlarging top of previously drilled hole to given depth to provide square shoulder for head of bolt or capscrew Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Standard Operations Spot-Facing Smoothing and squaring surface around hole to provide seat for head of cap screw or nut Boring bar fitted with double-edged cutting tool Pilot section on end to fit into existing hole Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Principal Types of Drilling Machines Wide variety of drill presses Size of drill press may be designated in different ways by different companies Some state size as distance from center of spindle to column of machine Others state size by diameter of largest circular piece that can be drilled in center

Sensitive Drill Press Parts Only hand feed mechanism Control downfeed pressure Manufactured in bench and floor model Four main parts Base, column, table and drilling head Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Sensitive Drill Press Parts Base Provides stability for machine Cast iron with holes to be bolted to table or bench Slots or ribs in base allow work-holding device or workpiece to be fastened Column Accurate cylindrical post that fits in base Table may be adjusted any point (base to head) Drill press head mounted near top Table The table, either round or rectangular in shape, is used to support the workpiece to be machined. The table, whose surface is at 90° to the column, may be raised, lowered, and swiveled around the column. On some models, it is possible to tilt the table in either direction for drilling holes on an angle. Slots are provided in most tables to allow jigs, fixtures, or large workpieces to be clamped directly to the table. Drilling Head The head, mounted close to the top of the column, contains the mechanism used to revolve the cutting tool and advance it into the workpiece. The spindle, which is a round shaft that holds and drives the cutting tool, is housed in the spindle sleeve, or quill. The spindle sleeve does not revolve but slides up and down inside the head to provide a downfeed for the cutting tool. The end of the spindle may have a tapered hole to hold taper shank tools or may be threaded or tapered for attaching a drill chuck (Fig. 38-2).

Sensitive Drill Press Parts Table Round or rectangle Used to support workpiece to be machined Surface 90º to column (move around) Drilling Head Mechanism used to revolve cutting tool Spindle: round shaft holds cutting tool Quill: houses spindle

Sensitive Drill

Sensitive Drill

Sensitive Drill

Upright Drilling Machine Larger and heavier Differences from sensitive-type drill Equipped with gearbox for variety of speeds Spindle may be advanced by: hand lever, handwheel, and automatically by feed mechanism Table raised or lowered by mechanism Some have reservoir in base for coolant storage Multispindle head can be used (20+ spindles)

Upright Drill Press

Upright Drill Press

Radial Drill Sometimes called radial-arm drill Advantages of this machine Larger and heavier work may be machined Drilling head raised or lowered Drilling head moves rapidly to any desired location while workpiece remains clamped More power Head may swivel so holes can be drilled on angle

Radial Drill Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Radial Drill Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Radial Drill Parts Base Column Heavy, box-type, ribbed cast iron or welded steel Used to bolt machine to floor and provide coolant reservoir Table may be bolted to base for small work Column Upright cylindrical member fitter to base Supports radial arm at right angles Radial Arm The arm is attached to the column and may be raised and lowered by means of a power-driven elevating screw. The arm may also be swung about the column and may be clamped in any desired position. It also supports the drive motor and drilling head. Drilling Head The drilling head is mounted on the arm and may be moved along the length of the arm by means of a traverse handwheel. The head may be clamped at any position along the arm. The head houses the change gears and controls for the spindle speeds and feeds. The drill spindle may be raised or lowered manually by means of the spindle-feed handles. When the spindle-feed handles are brought together, automatic feed is provided to the drill spindle.

Radial Drill Parts Radial arm Drilling head Attached to column May be raised and lowered by means of power-driven elevating screw Supports drive motor and drilling head Drilling head Mounted on arm and moved along length of arm by traverse handwheel Drill spindle may be raised or lowered

Radial Drill Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Radial Drill Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Radial Drill Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Radial Drill Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.