L a t h e

1. L a t h e

2. Types of Lathes: • Center Lathe • Engine Lathe • Bench Lathe • Capstan & Turret Lathes • Automatic Lathes • Multi Spindle Lathes • Vertical Turret Lathes • CNC Lathes Lathe Machines

3. Bench Lathes. Special-purpose Lathes. • Special applications (such as railroad wheels, gun barrels, and rolling-mill rolls) with workpiece sizes as large as 1.7 m in diameter by 8 m in length and capacities of 450 kW Tracer Lathes • With attachments capable of turning parts with various contours • have been replaced largely by numerical-control lathes. Automatic Lathes • medium to high volume production, parts are fed and removed automatically, Lathes that do not have tailstocks are called chucking machines or chuckers. They are either single- or multiple-spindle types. Automatic Bar Machines (Screw Machines): high production rate of screws

4. Turret Lathes • multiple cutting operations [turning, boring, drilling, thread cutting, and facing] • several cutting tools are mounted on the hexagonal main turret which is rotated for each specific operation • Vertical turret lathes also are available; they are more suitable for short, heavy workpieces with diameters as large as 1.2 m. • ram-type turret lathe-one in which the ram slides in a separate base on the saddle. • The short stroke of the turret slide limits this machine to relatively short workpieces and light cuts in both small- and medium-quantity production. • In the saddle type, the main turret is installed directly on the saddle, which slides along the bed.

5. Turret Lathe Schematic illustration of the components of a turret lathe. Note the two turrets: square and hexagonal (main).

7. Parts of an “Engine” Lathe Kalpakjian

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9. Thank You!

10. Lathe Parts • Lathe bed • Made from rigid cast Iron • Accurately machined slideways • Slideways guide carriage & tailstock • Headstock on upper end of the lathe bed

11. Lathe parts • Headstock • Holds lathe spindle and gears • Chuck is fitted to spindle • Spindle is hollow for long bars

12. Lathe parts • Tailstock • Can be moved along slideways • Can be clamped in any location • Inside tapered to hold drill chuck

13. Lathe parts • Carriage • Moves along bed between tailstock and headstock • Saddle – across the lathe • Apron – hangs down in front

14. Lathe parts • Cross Slide • Fitted on the Saddle • Moves cutting tool at right angles to lathe bed

15. Lathe parts • Top Slide (Compound slide) • Fitted to top of Cross slide • Carries toolpost and cutting tool • Can rotate to any angle • Is used to turn tapers

16. Lathe parts • Feed shaft • Used to move the Carriage automatically • Lead screw • Used when screw cutting on the lathe

17. Lathe Parts • Three Jaw Chuck • Self centring • Holds round and hexagonal work • 3 jaws are connected • Jaws are stamped 1,2 & 3 and fitted in order • Chuck key used to open

18. 3 or 4 jaws • 3 jaws generally have a geared-scroll design that makes the jaws self-centering. Used for round workpieces [bar stock, pipes tubing] • 4 jaw independent chucks. Used for square, rectangular, or odd shaped more ruggedly than three jaw chucks, four-jaw chucks are used for heavy workpieces • jaws can be reversed • chucks: power actuated [pneumatically or hydraulically] or manual chucks available in various designs & sizes: selection depends on: • type & speed of operation • workpiece size • production & accuracy requirements. • jaw forces requirements

19. Lathe parts • Toolpost • Fitted on top slide and carries the cutting tool or the cutting tool holder • Can adjust the height on some types • Can carry 4 different tool holders

20. The drive plate may be fastened to the spindle by threads, by a cam lock mechanism, or by a threaded collar and key.

21. Lesson 24 Lathes The drive plate ( 卡盘）may be fastened to the spindle by threads, by a cam lock mechanism, or by a threaded collar and key. 卡盘可以通过螺纹锁紧，凸轮锁紧机构或螺纹垫圈和键固定在主轴上。

22. The lathe be is cast iron and provides accurately ground sliding surfaces(way) on which the carriage rides.

23. The lathe carriage is a H-shaped casting on which the cutting tool is mounted in a tool holder.

24. The apron hangs from the front of the carriage and contains the driving gears that move the tool and carriage along or across the way to provide the desired tool motion.

25. A compound rest, located above the carriage provides for rotation of the tool holder through any desired angle.

26. A hand wheel and feed screw are provided on the compound rest for linear motions of the tool.

27. The cross feed is provided with a hand wheel and feed screw for moving the compound rest perpendicular to the lathe way.

28. A gear train in the apron provides power feed for the carriage both along and across the way.

29. The feed box contains gears to impart motion to the carriage and control the rate at which the tool moves relative to the workpiece.

30. Since the transmission in the feed box is driven from the spindle gears, the feeds are directly related to the spindle speed. The feed box gearing is also used in thread cutting and provides from 4 to 224 threads per in.

31. The connecting shaft between the feed box and the lathe apron are the feed rod and the lead screw.Many lathe manufacturers combine these two rods in one, a practice that reduces the cost of the machine at the expense of accuracy.

32. The feed rod is used to provide tool motion essential for accurate workpiece and good surface finishes. The lead screw is used to provide the accurate lead necessary for the thread cutting.

33. Turning Operations • Machine Tool – LATHE • Job (workpiece) – rotary motion • Tool – linear motions • “Mother of Machine Tools “ • Cylindrical and flat surfaces

34. Some Typical Lathe Jobs Turning/Drilling/Grooving/ Threading/Knurling/Facing...

35. Size of Lathe Swing Workpiece Length

36. Size of Lathe .. Example: 300 - 1500 Lathe • Maximum Diameter of Workpiece that can be machined = SWING (= 300 mm) • Maximum Length of Workpiece that can be held between Centers (=1500 mm)

37. WorkholdingDevices • Equipment used to hold • Workpiece – fixtures • Tool - jigs Securely HOLD or Support while machining

38. Workholding Devices .. Chucks Three jaw Four Jaw

39. Workholding Devices .. Centers

40. Operating/Cutting Conditions • Cutting Speed v • Feed f • Depth of Cut d

41. Operating Conditions

42. Operating Conditions.. Cutting Speed D – Diameter (mm) N – Revolutions per Minute (rpm) The Peripheral Speed of Workpiece past the Cutting Tool =Cutting Speed

43. Operating Conditions.. Feed f – the distance the tool advances for every rotation of workpiece (mm/rev)

44. Operating Conditions.. Depth of Cut perpendicular distance between machined surface and uncut surface of the Workpiece d = (D1 – D2)/2 (mm)

45. 3 Operating Conditions

46. Turning Facing knurling Grooving Parting Chamfering Taper turning Drilling Threading Operations on Lathe Operations on Lathe ..

47. Turning Operations on Lathe .. Cylindrical job

48. Turning .. Operations on Lathe .. Cylindrical job

49. Turning .. Operations on Lathe .. • Excess Material is removed to reduce Diameter • Cutting Tool: Turning Tool • a depth of cut of 1 mm will reduce diameter by 2 mm

50. Facing Operations on Lathe .. Flat Surface/Reduce length