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Unformatted text preview: Turning, Boring and Related Operations
Chapter 22 Lathes Wheel set from Narrow Gauge Steam Engine Chama, NM 30" Diameter December 2005 Lathes The lathe is the most common machine tool. Historical Notes 1775 John Wilkinson, Boring machine for James Watt steam engine Henry Maudsley slide carriage 1800 Lathes Common Operations Turning: Process of machining the external cylindrical and conical surfaces. Boring: Machining the internal cylindrical and conical surface from an existing hole. Threading Facing Drilling, reaming, tapping, knurling Major Components
Bed Base, foundation for the lathe. Heavy, rigid casting; usually gray cast iron or nodular cast iron Ways Rails or guides running longitudinally on the bed. Hardened steel, precision ground Headstock Fixed part of the lathe - Hollow spindle, rotational motion to the part - Gears for speed selection of spindle rotation - Work holding equipment mounts to spindle Major Components
Motor Typically 5 to 25 HP. Belt, chain, or gear drive between motor and headstock Leadscrew - used for thread cutting Feedrod - Provides power feed for carriage and cross slide Gearbox - Provides power for leadscrew and feed rod Tailstock - Consists of three main parts. - Lower casting, mounts to ways - Upper casting, moves transversely allowing alignment of tailstock and headstock center lines - Quill: Hollow tube which moves longitudinally by handwheel. Used to hold centers or tooling Carriage Heavy, H-shaped casting that rides on the ways of the lathe. Cross Slide Compound Rest Apron control of the carriage and leadscew, feedrod, and cross-slide power feed Size and Specification of Lathes Swing: Maximum diameter which can be turned. Distance between centers: Maximum length of part that can be turned when mounted by centers. Types of Lathes Engine Lathe: Most common type of lathe. Actual machining time ~ 30% Toolroom Lathe: greater accuracy, shorter beds, small parts Turret Lathe: (Turret replaces the tailstock) Ram Saddle Slant Bed Vertical Turret Lathe: Used for larger parts Screw Machines Turret Lathes Ram Turret Lathe Saddle Turret Lathe Okuma Lathe Swiss Screw Machines Sliding Headstock and Guide Bushing Spindle Speed 100010,000 RPM Cutting tools move radically only. Longitudinal feed is from moving the headstock Brown and Sharp Screw Machine Small Automatic Turret Lathe Turret mounted in vertical plane on a ram Tools holders can be mounted on cross-slides Movement controlled by cams Web Sites: Cox Manufacturing SwissTurn Work Holding Devices Between Centers Two types of centers Dead Live The part is driven using a dog and dog plate or a face driver Collets Faceplate Chucks Chucks 3 jaw chucks Chucks 4 jaw chuck Accessories Steady Rest Used to support long, slender parts during the cutting. Prevents part from deflecting due to cutting forces. Clamps to the lathe ways. Follow Rest Mounts to the carriage, similar to steady rest. Tracer Boring Machines Vertical Boring Machine (VTL) Workpiece rotates about a vertical axis Tool heads move vertically and horizontally, swivel to permit boring on an angle Machine Information Table Diameter 54" Motor HP 40 R.H. Swivel turret head L. H. Swivel ram head Boring Machines Horizontal Boring Machine Workpiece fixed to movable table Rotating spindle, tool rotates
Machine Notes Rotary Table Spindle diameter Motor HP Weight Cross travel Longitudinal travel Vertical travel Spindle Travel 63" x 71" 5" 30 74,000 lbs 55" 63" 55" 40" Boring Operations Compared to turning due to tool deflection
Lower feed rate Lower depths of cut ...
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This note was uploaded on 05/20/2008 for the course MET 153 taught by Professor Kohser during the Spring '08 term at Missouri S&T.
- Spring '08