Lathe-Jigs-Fixtures Lecture notes useful for basics
- 2. Overview Lathe: Classification of Lathes, Engine lathe, Specification and mechanisms of engine lathe, tool & work holding devices and attachments. CNC lathe – construction, Drive mechanisms, Automatic tool changer, motors. Jigs and Fixtures: Definition, advantages, elements, principles of location and clamping, degrees of freedom.
- 3. Classification of Lathes According to configuration: Horizontal,Vertical. According to purpose of use: General / Single / Special purpose. According to size or capacity: Small, Medium, Large. According to degree of automation: Manual: Centre Lathe Semi-Automatic: Capstan lathe,Turret lathe Automatic: Swiss type automatic According to type of automation: Fixed: Swiss type automatic Flexible: CNC lathe
- 4. Lathe Specifications Technical Specification of center lathe Machine: Swing over machine bed. Swing over cross slide Distance between centers Overall length of bed
- 5. Lathe The lathe is a machine tool used principally for shaping articles of metal by causing the workpiece to be held and rotated by the lathe while a tool bit is advanced into the work causing the cutting action:
- 6. Parts of Lathe 1. Headstock 2. Tailstock 3. Bed 4. Guide ways 5. Carriage 6. Lead Screw, Feed Rod and Rack 7. Back Gears 8. Quick-change Gearbox
- 7. Parts of Lathe Headstock The headstock attaches to the left side of the bed. It houses the headstock spindle, the bearings, the gears and the belts used to drive the spindle
- 8. Parts of Lathe Tailstock The tailstock consists of a heavy two-part casting that sits on the guide ways and is clamped in place with the tailstock clamp. The top part of the casting may be adjusted from side to side as needed for parallel or taper turning.
- 9. Parts of Lathe Bed The bed of a lathe is a heavy iron casting. It must be strong enough to support large workpieces and rigid enough not to distort under the stress of machining.
- 10. Parts of Lathe Guide ways Guide ways are machined on the top of the bed and are hardened to resist wear. All modern machines use an inverted prism design.
- 11. Parts of Lathe Carriage The carriage rides directly on the ways and is made up of the saddle,crossslide,compound rest,apron and various controls.
- 12. Parts of Lathe Saddle The saddle is an H-shaped casting that rides directly on the ways. Saddle movement is longitudinal, or parallel, to the axis of the machine spindle. Cross-Slide The cross-slide sits on top of the saddle and moves at right angles to the axis of the workpiece.The cross-slide is moved by turning a handwheel, which turns a screw. A graduated dial on the handwheel measures the movement of the cross-slide. Compound Rest The compound rest sits on top of the cross-slide. It is a small sliding mechanism that allows the tool to be adjusted a short distance.The compound rest can be swivelled 360º to obtain any angle to the machine spindle face. Most lathes provide power feed to the saddle and cross-slide, but not to the compound rest.The tool post mounts to the compound rest using theT-slot.
- 13. Parts of Lathe Cross-feed handwheel Compound rest
- 14. Parts of Lathe Apron The apron hangs down in front of the saddle and houses the drive gears and split nut mechanism.The split nut lever,found on the apron,closes the split nut on the lead screw when thread cutting.
- 15. Parts of Lathe Lead Screw, Feed Rod and Rack
- 16. Parts of Lathe Lead Screw, Feed Rod and Rack The quick-change gearbox drives the lead screw or feed rod. A lead screw is an accurate threaded rod that runs the length of the bed. There is a split nut housed in the carriage. When the nut engages the lead screw, it moves the carriage at a predetermined speed relative to the rotation of the spindle. The feed rod transmits power from the quick-change gearbox to another set of gears within the carriage.A pinion (a small gear) engages the rack,which is found just under the front ways, to move the carriage under power. The feed rod moves the carriage at a slower rate (more suitable for turning) than the lead screw does for threading.
- 17. Parts of Lathe Back Gears The back gears link the spindle to the input shaft of the quick-change gearbox. It is often necessary to remove one set of gears and replace it with another in order to achieve a particular feed rate or pitch listed on the quick- change gearbox.
- 18. Parts of Lathe Quick-Change Gearbox The movement of the carriage is timed with the rotation of the spindle. The quick-change gearbox allows you to change gears quickly and easily by shifting levers.
- 20. Lathe Accessories 1. Three-Jaw chuck 2. Four-Jaw Chuck
- 21. Lathe Accessories Three Jaw Chuck: •This is an Universal chuck. •Also called self centering chuck. •Used for round and Hexagonal w/p.
- 22. Lathe Accessories Four Jaw Chuck: •This is an Independent chuck. •It has 4 reversible jaws. •Each jaw can move independently to accommodate different shaped workpiece like square, round and irregular. •Used to make eccentric parts.
- 28. Lathe Accessories Steady Rest Follower Rest
- 29. Lathe Attachments Taper turning attachment Copy turning attachments Milling and cylindrical grinding attachments Spherical turning attachments Relieving attachment