turning operations l a t h e. turning operations machine tool – lathe job (workpiece) – rotary...

Download Turning Operations L a t h e. Turning Operations Machine Tool – LATHE Job (workpiece) – rotary motion Tool – linear motions  “Mother of Machine Tools

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  • Slide 1
  • Turning Operations L a t h e
  • Slide 2
  • Turning Operations Machine Tool LATHE Job (workpiece) rotary motion Tool linear motions Mother of Machine Tools Cylindrical and flat surfaces
  • Slide 3
  • Some Typical Lathe Jobs Turning/Drilling/Grooving/ Threading/Knurling/Facing...
  • Slide 4
  • The Lathe
  • Slide 5
  • Bed Head Stock Tail Stock Carriage Feed/Lead Screw
  • Slide 6
  • Main Parts Bed Headstock Feed and lead screws Carriage Tailstock 6
  • Slide 7
  • Lathe Bed Heavy, rugged casting Made to support working parts of lathe On top section are machined ways Guide and align major parts of lathe 7
  • Slide 8
  • Lathe Bed 8
  • Slide 9
  • Headstock Clamped on left-hand end of bed Headstock spindle Hollow cylindrical shaft supported by bearings Provides drive through gears to work-holding devices Live center, faceplate, or chuck fitted to spindle nose to hold and drive work Driven by stepped pulley or transmission gears Feed reverse lever Reverses rotation of feed rod and lead screw 9
  • Slide 10
  • Headstock 10
  • Slide 11
  • Headstock 11 Back Gear arrangement Headstock belt drive
  • Slide 12
  • Quick-Change Gearbox Contains number of different-size gears Provides feed rod and lead-screw with various speeds for turning and thread-cutting operations Feed rod advances carriage when automatic feed lever engaged Lead screw advances the carriage for thread- cutting operations when split-nut lever engaged 12
  • Slide 13
  • Quick-Change Gearbox 13
  • Slide 14
  • Carriage Used to move cutting tool along lathe bed Consists of three main parts Saddle H-shaped casting mounted on top of lathe ways, provides means of mounting cross-slide and apron Cross-slide Apron 14
  • Slide 15
  • 15 Carriage < Saddle < Apron
  • Slide 16
  • Carriage 16
  • Slide 17
  • Carriage 17
  • Slide 18
  • 18 Apron The apron attached to the front of the carriage, holds most of the control levers. These include the levers, which engage and reverse the feed lengthwise (Z-axis) or crosswise (X-axis) and the lever which engages the threading gears. The apron is fastened to the saddle, houses the gears and mechanisms required to move the carriage and cross-slide automatically. The apron hand wheel can be turned manually to move the carriage along the Lathe bed. This hand wheel is connected to a gear that meshes in a rack fastened to the Lathe bed. The automatic feed lever engages a clutch that provides the automatic feed to the carriage
  • Slide 19
  • Cross-slide Mounted on top of saddle Provides manual or automatic cross movement for cutting tool Compound rest (fitted on top of cross-slide) Used to support cutting tool Swiveled to any angle for taper-turning Has graduated collar that ensure accurate cutting-tool settings (.001 in.) (also cross- slide) 19
  • Slide 20
  • Cross-slide 20
  • Slide 21
  • 21
  • Slide 22
  • Top Slide (Compound slide) Fitted to top of Cross slide Carries tool post and cutting tool Can rotate to any angle Is used to turn tapers 22
  • Slide 23
  • Tailstock Upper and lower tailstock castings Adjusted for taper or parallel turning by two screws set in base Tailstock clamp locks tailstock in any position along bed of lathe Tailstock spindle has internal taper to receive dead center Provides support for right-hand end of work 23
  • Slide 24
  • 24 Tailstock Supports long workpieces when machining. 60 degree rotating center point. Drill Chuck Turn the tailstock handwheel to advance the ram.
  • Slide 25
  • Tailstock 25
  • Slide 26
  • Lead Screw and Feed Rod 26 < Lead Screw < Feed Rod
  • Slide 27
  • Types of Lathes Engine Lathe Speed Lathe Bench Lathe Tool Room Lathe Special Purpose Lathe Gap Bed Lathe
  • Slide 28
  • Size of Lathe Workpiece Length Swing
  • Slide 29
  • 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)
  • Slide 30
  • Workholding Devices Equipment used to hold Workpiece fixtures Tool - jigs Securely HOLD or Support while machining
  • Slide 31
  • Chucks Three jaw Four Jaw Workholding Devices..
  • Slide 32
  • 32 Chucks Used extensively for holding work for lathe machining operations Work large or unusual shape Most commonly used lathe chucks Three-jaw universal Four-jaw independent Collet chuck
  • Slide 33
  • 33 Three-jaw Universal Chuck Holds round and hexagonal work Grasps work quickly and accurate within few thousandths/inch Three jaws move simultaneously when adjusted by chuck wrench Caused by scroll plate into which all three jaws fit Two sets of jaw: outside chucking and inside chucking
  • Slide 34
  • 34 Three-jaw Universal Chuck
  • Slide 35
  • 35 Three jaw self centering chuck
  • Slide 36
  • 36 Four-Jaw Independent Chuck Used to hold round, square, hexagonal, and irregularly shaped workpieces Has four jaws Each can be adjusted independently by chuck wrench Jaws can be reversed to hold work by inside diameter
  • Slide 37
  • 37 Four-Jaw Independent Chucks
  • Slide 38
  • 38 With the four jaw chuck, each jaw can be adjusted independently by rotation of the radially mounted threaded screws. Although accurate mounting of a workpiece can be time consuming, a four-jaw chuck is often necessary for non-cylindrical workpieces.
  • Slide 39
  • Mandrels Workpiece (job) with a hole Workholding Devices..
  • Slide 40
  • Mandrels 40 Holds internally machined workpiece between centers so further machining operations are concentric with bore Several types, but most common Plain mandrel Expanding mandrel Gang mandrel Stub mandrel
  • Slide 41
  • 41 Mandrels to Hold Workpieces for Turning Figure 23.8 Various types of mandrels to hold workpieces for turning. These mandrels usually are mounted between centers on a lathe. Note that in (a), both the cylindrical and the end faces of the workpiece can be machined, whereas in (b) and (c), only the cylindrical surfaces can be machined.
  • Slide 42
  • Rests Workholding Devices.. Steady Rest Follower Rest
  • Slide 43
  • 43 Steadyrest Used to support long work held in chuck or between lathe centers Prevent springing Located on and aligned by ways of the lathe Positioned at any point along lathe bed Three jaws tipped with plastic, bronze or rollers may be adjusted to support any work diameter with steadyrest capacity
  • Slide 44
  • 44 Steadyrest
  • Slide 45
  • 45 Follower Rest Mounted on saddle Travels with carriage to prevent work from springing up and away from cutting tool Cutting tool generally positioned just ahead of follower rest Provide smooth bearing surface for two jaws of follower rest
  • Slide 46
  • 46 Follower Rest
  • Slide 47
  • Operating/Cutting Conditions 1.Cutting Speed v 2.Feed f 3.Depth of Cut d
  • Slide 48
  • Operating Conditions
  • Slide 49
  • Cutting Speed The Peripheral Speed of Workpiece past the Cutting Tool =Cutting Speed Operating Conditions.. D Diameter (mm) N Revolutions per Minute (rpm)
  • Slide 50
  • Feed f the distance the tool advances for every rotation of workpiece (mm/rev) Operating Conditions..
  • Slide 51
  • Depth of Cut perpendicular distance between machined surface and uncut surface of the Workpiece d = (D 1 D 2 )/2 (mm) Operating Conditions..
  • Slide 52
  • 3 Operating Conditions
  • Slide 53
  • Selection of.. Workpiece Material Tool Material Tool signature Surface Finish Accuracy Capability of Machine Tool Operating Conditions..
  • Slide 54
  • Material Removal Rate MRR Volume of material removed in one revolution MRR = D d f mm 3 Job makes N revolutions/min MRR = D d f N (mm 3 /min) In terms of v MRR is given by MRR = 1000 v d f (mm 3 /min) Operations on Lathe..
  • Slide 55
  • MRR dimensional consistency by substituting the units Operations on Lathe.. MRR : D d f N (mm)(mm)(mm/rev)(rev/min) = mm 3 /min
  • Slide 56
  • Operations on Lathe Turning Facing knurling Grooving Parting Chamfering Taper turning Drilling Threading Operations on Lathe..
  • Slide 57
  • Turning Cylindrical job Operations on Lathe..
  • Slide 58
  • Turning.. Cylindrical job Operations on Lathe..
  • Slide 59
  • Turning.. Excess Material is removed to reduce Diameter Cutting Tool: Turning Tool a depth of cut of 1 mm will reduce diameter by 2 mm Operations on Lathe..
  • Slide 60
  • Facing Flat Surface/Reduce length Operati