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Drilling and boring

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drilling and boring machines

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Drilling and boring

  1. 1. UNIT-III(B) DRILLING AND BORING MACHINES By D. Kanaka Raja Department of mechanical engineering, AITS
  2. 2.  Drilling is the operation of producing circular hole in the work-piece by using a rotating cutter called DRILL.  The machine used for drilling is called drilling machine.  The drilling operation can also be accomplished in lathe, in which the drill is held in tailstock and the work is held by the chuck.  The most common drill used is the twist drill.  It is the simplest and accurate machine used in production shop. DRILLING
  3. 3. DRILLING MACHINE  Drilling machine  Spindle  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, counter boring, countersinking, spot-facing
  4. 4. WORKING PRINCIPAL OF DRILLING MACHINE  The rotating edge of the drill exerts a large force on the workpiece and the hole is generated.  The removal of metal in a drilling operation is by shearing and extrusion.
  5. 5. SPECIFICATIONS OF DRILLING MACHINE  Size of drilling table.  Largest bit the machine can held.  Maximum size of the hole that can be drilled.  Maximum size the work piece that can be held.  Power of the motor, spindle speed or feed.
  6. 6. TOOL NOMENCLATURE
  7. 7. TOOL NOMENCLATURE
  8. 8. TOOL NOMENCLATURE
  9. 9. TOOL NOMENCLATURE
  10. 10. TOOL NOMENCLATURE
  11. 11. TYPES OF DRILLING MACHINES a) Based on construction: Portable, Sensitive or bench drilling machine Radial, up-right, Gang, Multi-spindle Automatic Turret Deep hole b)Based on Feed: Hand and Power driven Portable drilling machine
  12. 12. PORTABLE DRILLING MACHINE  It is a small light weight, compact and self contained unit that can drill holes upto 12.5 mm diameter.  The machine is driven by a small electric motor operating at high speed.  The machine is capable of drilling holes in the workpieces in any position.
  13. 13. SENSITIVE OR BENCH DRILLING MACHINE  These are light duty vehicles.  Mounted on benches.  To drill small diameter holes ,a twist drill is fitted in the drill chuck.  This design is used to drill hole from 1.5mm to 15mm diameter.  The controls are light and delicate speeds from 800 to 900 rpm are typical range.
  14. 14. SENSITIVE DRILLING MACHINE
  15. 15. DRIVE MECHANISM IN SENSITIVE DM
  16. 16. UP-RIGHT DRILLING MACHINE  Similar to sensitive drills have power feed mechanism for rotating drills and are designed for heavier.  It is used for heavier work.  Drill holes upto 50mm  Table can move vertically and radially
  17. 17. UP-RIGHT DRILLING MACHINE
  18. 18. RADIAL DRILLING MACHINE  It the largest and most versatile used fro drilling medium to large and heavy work pieces.  It can be radially adjusted around the column in any position over the work to get different size and shapes of work.  The moments may be either manual or power driven.  The table is to be rotated through 360 deg.  The wide rang of power are as well as sensitive and geared manual feeds.
  19. 19. RADIAL DRILLING MACHINE  This machine is used for drilling medium to large heavy work pieces.  Types of radial drilling machine. 1) plain radial drilling machine 2) semi universal drilling machine 3) universal drilling machine
  20. 20. RADIAL DRILLING MACHINE
  21. 21. DRIVE IN RDM
  22. 22. GANG DRILLING MACHINE  When drilling spindles are mounted on a single table, it is known as a gang drill.  Each of these spindles can be independently set for different speed and depth of cut.  Such machines are useful when number of holes of different sizes are to be drilled on the same work piece.  Apart from drilling, a number of other machining operations like reaming counter boring, tapping etc can also be performed at a time on this machine.
  23. 23. GANG DRILLING MACHINE
  24. 24. TURRET TYPE DRILLING MACHINE  The stations are set up with a variety of tools numerical control is a also available.  Two fixtures can be located side by on the workable table, thus permitting loading and unloading of one part while the other part is being machined this reduces the machine cycle.
  25. 25. TURRET TYPE DRILLING MACHINE
  26. 26. DEEP HOLE DRILLING  These machines are used for drilling holes whose depth exceed normal drill size. These machines are operated at high speed and low feed.  These machines are either horizontal or vertical. The work or the drill may revolve. most machines are of horizontal construction using a center cut gun drill, which has a single cutting edge with a straight flute running througout its length.  These machines are very useful for drilling deep holes in rifle travels, crankshafts.
  27. 27. DEEP HOLE DM
  28. 28. DEEP HOLE DRILLING MACHINE  Very deep holes of L/D ratio 6 to even 30, required for rifle barrels, long spindles, oil holes in shafts, bearings, connecting rods etc, are very difficult to make for slenderness of the drills and difficulties in cutting fluid application and chip removal.  Such drilling cannot be done in ordinary drilling machines and bordinary drills.  It needs machines like deep hole drilling machine such as gun drilling machines with horizontal axis which are provided with
  29. 29. DRILLING OPERATIONS…  Operations that can be performed in a drilling machine are  Drilling  Reaming  Boring  Counter boring  Countersinking  Tapping and  Spot Facing
  30. 30. DRILLING OPERATIONS…
  31. 31. OPERATIONS PERFORMED  Drilling  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
  32. 32. OPERATIONS PERFORMED  Reaming  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
  33. 33. OPERATIONS PERFORMED  Tapping  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
  34. 34. OPERATIONS IN DRILLING MACHINE
  35. 35. COUNTER BORE AND SPOT FACING
  36. 36. OPERATIONS IN DRILLING MACHINE
  37. 37. TOOL HOLDING DEVICES  Tool-holding devices are Used to hold or drive cutting tool  The different methods used for holding drill in a drill spindle are  By directly fitting in the spindle hole.  By using drill sleeve  By using drill socket  By using drill chuck
  38. 38. TOOL-HOLDING DEVICES  Drill press spindle provides means of holding and driving cutting tool  End may be tapered or threaded for mounting drill chuck  Most common  Drill chucks  Drill sleeves  Drill sockets
  39. 39. DRILL FIXED TO THE SPINDLE Drilling operations Drilling Centre Hole Drilling Deep Holes Drilling Thin Material Drilling Pilot Hole
  40. 40. DRILL CHUCKS  Most common devices used for holding straight- shank cutting tools  Most contain three jaws that move simultaneously when outer sleeve turned  Hold straight shank of cutting tool securely  Two common types  Key  Keyless
  41. 41. WORK HOLDING DEVICES
  42. 42. WORK HOLDING DEVICES
  43. 43. WORK HOLDING DEVICES
  44. 44. CHUCKS  Hold straight-shank drills  Mounted on drill press spindle  Taper – Threads • Held in spindle by self-holding taper in larger machines • Four types of drill chucks
  45. 45. TYPES OF DRILL CHUCKS  Key-type  Most common  Three jaws move simultaneously when outer sleeve turned  Tighten with key  Keyless  Chuck loosened or tightened by hand without key  Precision keyless  Holds smaller drills accurately
  46. 46. DRILL CHUCKS
  47. 47. TOOL HOLDER
  48. 48. DRILL TYPES
  49. 49. DRILL TYPES
  50. 50. TYPES OF CUTTERS Reamers :- Multi tooth cutting tool Accurate way of sizing and finishing the pre-existing hole. Accuracy of 0.005mm can be achieved Boring Tool:- Single point cutting tool. Boring tool is held in the boring bar which has the shank. Accuracy of 0.005mm can be achieved.
  51. 51. TYPES OF CUTTERS Countersinks :- Special angled cone shaped enlargement at the end of the hole Cutting edges at the end of conical surface. Cone angles of 60°, 82°, 90°, 100°, 110°, 120° Counter Bore Tool:- Special cutters uses a pilot to guide the cutting action . Accommodates the heads of bolts.
  52. 52. TYPES OF CUTTERS Combined Countersinks and central drill :- Special drilling tool to start the hole accurately. At the end it makes countersinks in the work piece. Gun drill :- Machining of lengthy holes with less feed rates. To overcome the heating and short life of the normal drill tool
  53. 53. TYPES OF CUTTERS Tapping:-  For cutting internal thread  Multi cutting edge tool.  Tapping is performed either by hand or by machine.  Minor dia of the thread is drilled and then tapping is done.
  54. 54. Drilling And Drills Types of drills – Twist drill: most common drill – Step drill: produces holes of two or more different diameters – Core drill: used to make an existing hole bigger
  55. 55. WORK HOLDING DEVICES
  56. 56. WORK HOLDING DEVICES  1. Machine Table Vice
  57. 57.  Step Blocks  Clamps  V-Blocks  Angles  Jigs  T- Slots Bolt WORK HOLDING DEVICES
  58. 58. DRILL MATERIALS The two most common types are 1. HSS drill - Low cost 2. Carbide- tipped drills - high production and in CNC machines Other types are Solid Carbide drill, TiN coated drills, carbide coated masonry drills, parabolic drills, split point drill
  59. 59. GRINDING OF DRILLS
  60. 60. GRINDING OF DRILLS
  61. 61. PARAMETERS DEFINITIONS  Cutting Speed (v):- It’s the peripheral speed of the drill v = *D*N where D = dia of the drill in m N = Speed of rotation in rpm Feed Rate (f):- It’s the movement of drill along the axis (rpm) Depth of Cut (d):- The distance from the machined surface to the drill axis d = D / 2
  62. 62. Material Removal Rate:- It’s the volume of material removed by the drill per unit time MRR = ( D2 / 4) * f * N mm3 / min Machining Time (T) :- It depends upon the length (l) of the hole to be drilled , to the Speed (N) and feed (f) of the drill t = L / f N min
  63. 63. REAMING
  64. 64. 86 WHAT IS MEANT BY BORING?  Boring is the process of enlarging an existing drilled holes with a single point cutting tool.  Boring operation can be performed on engine lathe Fig.1
  65. 65. CLASSIFICATION OF BORING MACHINE  Horizontal boring machine ( production machines) i. Table type HBM ii. Planer type HBM iii. Floor type HBM  Vertical boring machine( production machines)  Jig boring machine
  66. 66. HORIZONTAL BORING MACHINE
  67. 67. HORIZONTAL BORING MACHINE
  68. 68. HORIZONTAL BORING MACHINE  The table type or universal type is the most versatile and commonly used horizontal boring machine.  Bed a heavy and strong bed carries the entire load of different parts, work piece and tool over it.  Columns a two vertical columns, one on each end of the table.  Head stock the head stock can be moved vertically along the main column.  Load bearing end support it supports the end of a long boring bar and can be adjusted vertically along the end support column.  Horizontal table it is mounted on a saddle and can be moved horizontal forward and backward and side by moving the saddle.
  69. 69. HORIZONTAL BORING MACHINE
  70. 70. VERTICAL BORING MACHINE
  71. 71. VERTICAL BORING MACHINE
  72. 72. VERTICAL BORING MACHINE  The parts whose length or height is than diameter are machined.  The work is fastened on a horizontal revolving table and the cutting tool or tools which are stationary , advance vertically into it as the revolves.  Horizontal cross rail is carried on vertical sideways and carries the tool holder slide or slides.  Most machine also have a slide tool head.  Vertical boring machine is sometimes called a rotary planer and its cutting action on flat disc is identical with a planer.  These machines rated according to their table diameter, vary in size from 0.9 to 12m.
  73. 73. FLOOR TYPE BORING MACHINE
  74. 74. PLANER TYPE BM
  75. 75. MULTIPLE HEAD BM
  76. 76. TURRET TYPE BM
  77. 77. JIG BORING MACHINE  Jig boring machine resembles in appearance to a vertical milling machine.  Rugged enough for heavy cuts and sensitive enough for light cuts.  Essential for modern mass production  The machining accuracy of jig boring machine is very high, within a range of 0.0025 mm.
  78. 78. 101 NEED OF JIG BORING MACHINE Jig boring machines are mainly to perform machining operations like • Boring. • Drilling. • Reaming. • Counter boring holes in metal jigs • Counter-sinking holes in metal work pieces. Some jig boring machines are used for accurately enlarging the • Existing holes. • Making their diameters highly accurate  Boring can correct hole location, size, or alignment and can produce a good finish if a fine feed and correct tool are used.
  79. 79. 102 NEED OF JIG BORING MACHINE  Jig boring can also maintain high accuracy between multiple holes or holes and surfaces.  Some jig boring machines are designed to machine holes with the tightest tolerances possible with a machine tool.  The constant demand for accuracy within many branches of metalworking has been fulfilled with the help of applications possible by jig-boring machines.
  80. 80. JIG BORING MACHINE  Jig boring machines are used in precision tool room applications for locating and boring holes in • Jigs. • Fixtures. • Gauges. • And other precision parts.  To prevent the influence of ambient temperature on machining accuracy  Jig boring machines should be installed in a special environmental enclosures (i.e., in a temperature controlled rooms) with temperature maintained at a level of 20 °C.  Jig borers can be used as coordinate measuring machine for inspection and precision layout operation . 103
  81. 81. Simple Jig Boring Machine column spindle head quill boring toolspindle table bed saddle Line DiagramFig.2 PARTS OF JIG BORING MACHINE
  82. 82. JIG BORING MACHINE 105 Fig.3
  83. 83. JIG BORING MACHINE The main distinguishing features of these machines are :  The spindle and other parts are rigid to prevent deflection.  The spindle runs in preloaded ant frictional bearings.  The spindle housing is made of material having very low co-efficient of linear expansion .  For boring, the work pieces are clamped on the table by T-bolts and straps.  an existing hole is enlarged by using a single point tool.  The single point tool produces • Better surface finish. • And locates holes with maximum accuracy. 106
  84. 84. JIG BORING MACHINE  ⎯ high spindle speed  ⎯ high rigidity  ⎯ tool guide  ⎯ Pressurized cutting oil for effective cooling, chip removal and lubrication at the drill tip.  Deep hole drilling machines are available with both hard automation and CNC system.
  85. 85. JIG BORING MACHINE  The principle of boring using single point tool is illustrated in fig. 108 Fig.4
  86. 86. PARTS OF JIG BORING MACHINE
  87. 87. CUTTING FORCES
  88. 88. KINEMATIC SYSTEM OF GENERAL PURPOSE DRILLING MACHINE AND THEIR PRINCIPLE OF WORKING
  89. 89. KINEMATIC SYSTEM OF GENERAL PURPOSE DRILLING MACHINE AND THEIR PRINCIPLE OF WORKING  Mechanisms to enable transform and transmit motion(s) from the power source(s) to the cutting tool and the workpiece for the desired machining action.  a typical kinematic system of a very general purpose drilling machine, i.e., a column drilling machine having 12 spindle speeds and 6 feeds.  The kinematic system enables the drilling machine the following essential works;
  90. 90. KINEMATIC SYSTEM OF GENERAL PURPOSE DRILLING MACHINE AND THEIR PRINCIPLE OF WORKING  Cutting motion:  The cutting motion in drilling machines is attained by rotating the drill at different speeds (r.p.m.).  Like centre lathes, milling machines etc, drilling machines also need to have a reasonably large number of spindle speeds to cover the useful ranges of work material, tool material, drill diameter, machining and machine tool conditions.  The drill gets its rotary motion from the motor through the speed gear box (SGB) and a pair of bevel gears.  For the same motor speed, the drill speed can be changed to any of the 12 speeds by shifting the cluster gears in the SGB. The direction of rotation of the drill can be changed, if needed, by operating the clutch in the speed reversal mechanism, RM- s shown in the figure.
  91. 91. KINEMATIC SYSTEM OF GENERAL PURPOSE DRILLING MACHINE AND THEIR PRINCIPLE OF WORKING  Feed motion  In drilling machines, generally both the cutting motion and feed motion are imparted to the drill. Like cutting velocity or speed, the feed (rate) also needs varying (within a range) depending upon the tool-work materials and other conditions and requirements.  drill receives its feed motion from the output shaft of the SGB through the feed gear box (FGA), and the clutch. The feed rate can be changed to any of the 6 rates by shifting the gears in the FGB. And the automatic feed direction can be reversed, when required, by operating the speed reversal mechanism, RM-s as shown
  92. 92.  Tool work mounting  The taper shank drills are fitted into the taper hole of the spindle either directly or through taper socket(s).  Small straight shank drills are fitted through a drill chuck having taper shank.  The work piece is kept rigidly fixed on the bed (of the table).  Small jobs are generally held in vice and large or odd shaped jobs are directly mounted on the bed by clamping tools using the T-slots made in the top and side surfaces of the bed as indicated KINEMATIC SYSTEM OF GENERAL PURPOSE DRILLING MACHINE AND THEIR PRINCIPLE OF WORKING

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