Drilling Machine. Presenter: G. Tulloch

Transcription

1 Drilling Machine Presenter: G. Tulloch

2 Drilling machine A power operated machine tool which holds the drill in its spindle rotating at high speeds and when actuated move linearly against the work piece produces a hole.

3 Safety Precautions Do not support the work piece by hand use work holding device. Use brush to clean the chip No adjustments while the machine is operating Ensure for the cutting tools running straight before starting the operation. Never place tools on the drilling table Avoid loose clothing and protect the eyes. Ease the feed if drill breaks inside the work piece.

4 Precautions for Drilling machine Lubrication is important to remove heat and friction. Machines should be cleaned after use Chips should be removed using brush. T-slots, grooves, spindles sleeves, belts, pulley should be cleaned. Machines should be lightly oiled to prevent from rusting

5 What is Drilling Drilling is the process of cutting holes in metals by using a drilling machine and a drill

6 Drilling 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.

7 Belt drive system Belt Motor spindle Feed lever Rack & Pinnion Quill Spindle

8 Types of drilling machine. Portable drilling machine Sensitive drilling machine Radial drilling machine Pillar drilling machine

9 Portable drilling machine

10 Sensitive Drilling Machine Drill holes from 1.5 to 15mm Operator senses the cutting action so sensitive drilling machine

11 Bench drilling machine These are light duty machines used in small workshops. Also called Sensitive drilling machines because of its accurate and well balanced spindle. Holes of diameter 1 mm to 15 mm.

12 Pillar Drilling Machine Drill holes upto 50mm Table can move vertically and radially

13 Radial Drilling Machine It the largest and most versatile used fro drilling medium to large and heavy work pieces.

14 Radial drilling machine

15 Radial drilling machine These are heavy duty and versatile drilling machine used to perform drilling operate on large and heavy work piece. Holes up to 7.5 cm.

16 Hand Drill

17 Pistol-grip (corded) drill A drill in the shape of a pistol. Commonly called electric hand drill.

18 Cordless drills A cordless drill is a type of electric drill which uses rechargeable batteries.

19 parts Vertical main column Base Moving drill head Work table Electric motor Variable speed gear box and spindle feed mechanism.

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21 parts Heavy base Vertical column Horizontal arm Drilling head

22 The twist drill or drill bit

23 Drill Materials The two most common types are 1. HSS drill - Low cost 2. Carbide- tipped drills - high production and in CNC

24 Drill Bit A drill bit is a multi-point tool and typically has a pointed end. A twist drill is the most common type used

25 Drill Bit Flutes are incorporated to carry away the chips of metal. Shank- provide the drive. Can be tapered or parallel Body- tapers slightly in diameter from tip to shank to provide clearance

26 Twist drill Twist drills are available with parallel shanks up to 16mm diameter and with taper shanks up to 100mm diameter and are made from high-speed steel. Different helix angles are available for drilling a range of materials

27 Tool Nomenclature

28 Drill Bit Fit in chuck Fit direct into spindle

29 Drill Bit Features The point of the drill is ground to an angle of 118 degrees

30 The nomenclature of the twist drill is shown

31 Twist drills - Helix Types The helix angle of the twist drill is the equivalent of the rake angle on other cutting tools and is established during manufacture. The standard helix angle is 30 degrees, which, together with a point angle of 118, is suitable for drilling steel and cast iron.

32 Helix types Standard slow quick helix

33 Helix types Drills with a helix angle of 20 known as slowhelix drills are available with a point angle of 118 for cutting brass and bronze and with a point angle of 90 for cutting plastics materials. Quick-helix drills, with a helix angle of 40 and a point angle of 100, are suitable for drilling the softer materials such as aluminium alloys and copper

34 Drill Bit

35 Wood bits masonry steel

36 Centre drills Combination drills known as centre drills combine a number of operations in a single tool; for example drill and ream, drill two diameters, drill and chamfer, drill and countersink,

37 Centre drill

38 Types of cutters Reamers :- Multi tooth cutting tool Accurate way of sizing and finishing the preexisting hole. Boring Tool:- Single point cutting tool. Boring tool is held in the boring bar which has the shank.

39 Countersinks :- Types of cutters 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.

40 Types of cutters Tap For cutting internal thread Multi cutting edge tool. Tapping is performed either by hand or by machine.

41 Drilling Processes

42 Drilling operations Operations that can be performed in a drilling machine are Drilling Reaming Boring Counter boring Countersinking Tapping

43 Typical Drilling Processes

44 Reaming A reamer enters the workpiece axially and enlarges an existing hole to the diameter of the tool. A reamer is a multi-point tool that has many flutes, which may be straight or in a helix. Reaming removes a minimal amount of material and is often performed after drilling to obtain both a more accurate diameter and a smoother internal finish.

45 Reaming

46 Countersinking A countersink tool enlarges the top portion of an existing hole to a cone-shaped opening. Countersinking is performed after drilling to provide space for the head of a fastener, such as a screw, to sit flush with the workpiece surface. Common included angles for a countersink include 60, 82, 90, 100, 118, and 120 degrees.

47 Counter sinking This is an operation of making the end of a hole into a conical shape. Cutting speed = half of the cutting speed of drilling for same hole.

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49 Countersinking Bits

50 Countersinking Common included angles for a countersink include

51 Counterboring A counterbore tool enlarges the top portion of an existing hole to the diameter of the tool. Counterboring is often performed after drilling to provide space for the head of a fastener, such as a bolt, to sit flush with the workpiece surface. The counterboring tool has a pilot on the end to guide it straight into the existing hole

52 Counter boring This process involves increasing the size of a hole at only one end. Cutting tool will have a small cylindrical portion called pilot. Cutting speed = twothirds of the drilling speed for the same hole.

53 Counterboring Bit

54 Spotfacing Spotfacing provides a seat or flat surface at the entrance and surrounding area of a hole. This flat surface allows the bottom of a screw or bolt to seat squarely with the material. Spotfacing is commonly done on castings where irregular surfaces are found. Spotfacing may be performed on a drill press with a counterbore of suitable size for the operation. A proper size pilot must be used whenever this is done on the drill press.

55 Spot facing It is a finishing operation to produce flat round surface usually around a drilled hole, for proper seating of bolt head or nut. It is done using a special spot facing tool.

56 Spotfacing Making a sloped surface flat spotface To seat a nut Back spotface

57 Spotting Where holes in two parts are required to line up with each other, a technique known as spotting is carried out. The top part is marked out and drilled. The two parts are then carefully positioned and clamped together.

58 Spotting The holes in the bottom part are transferred by spotting through from the top part. Drilling of the bottom part can then proceed in the knowledge that both sets of holes are identical, which may not be the case if both parts are marked out and drilled individually.

59 Operations in drilling machine

60 Operations in drilling machine

61 Counter bore and spot facing

62 Boring It is process carried on a drilling machine to increase the size of an already drilled hole. Initially a hole is drilled to the nearest size and using a boring tool the size of the hole is increased.

63 Tapping Process of cutting internal threads with a thread tool called tap.

64 Tool Holding

65 Tool Holding devices 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 chuck

66 Tool Holding parallel shank drill Drills and similar tools with parallel shanks are held in a drill chuck. By rotating the outer sleeve, the jaws can be opened and closed. To ensure maximum grip, the chuck should be tightened using the correct size of chuck key. This prevents the drill from spinning during use and chewing up the drill shank. Drill bit is only gripped by the shank

67 The Drill Chuck Keyless Chuck Chuck Morse Taper Chuck Key

68 Drill fixed to the spindle

69 Tool Holding Holding taper shank drills

70 Tool Holding Where a cutting tool or chuck has a Morse taper smaller than that of the spindle, the difference is made up by using a sleeve. Morse Taper Sleeve For example, a drill with a No. 1 Morse-taper shank to be fitted in a spindle with a No. 2 Morse taper would require a 1 2 sleeve.

71 Morse Taper Sleeve

72 Drill Drift To remove a shank from the spindle, a taper key known as a drift is used.

73 Using the drill drift The drift is inserted through a slot in the spindle Strike here to remove Most modern machines have a built-in drift

74 Workholding

75 Work Holding Devices Step Blocks Clamps V-Blocks Angles Jigs T- Slots Bolt

76 NEVER HOLD WORK BY HAND

77 Drilling Machine Vice The Machine Vice has slots in the side of the base of the vice which enable the user to screw the Machine Vice to the Drilling Machine table.

78 Clamping set Direct Clamping

79 Vee Blocks & Clamps used when drilling round bar

80 Hand Vice used on drilling machine to clamp sheet metal

81 An angle plate is a work holding device used as a fixture in metalworking.

82 The angle plate is made from high quality material that has been stabilized to prevent further movement or distortion. Slotted holes or T bolt slots are machined into the surfaces to enable the secure attachment or clamping of workpieces to the plate, and also of the plate to the worktable.

83 Pilot Drilling Pilot hole is a smaller hole drill before a large one.

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85 Drilling holes to depth Holes can be drilled to a particular depth by setting the depth stop on the machine e.g. 15mm

86 Drilling Thin Material Support acts as thicker material so drill point is guided through work

87 Cutting speed Cutting speed for drilling is the rate at which the tool passes over the surface of the metal. i.e how fast the cutting tool is spinning. It is commonly expressed in metres per minute.

88 Cutting speeds depend on: The material being cut Condition and strength of the tool and machine Depth of cut Rate of feed Material of which the tool is made Availability of cutting fluid Size of the bit being used

89 Cutting speed selection The softer the work material, the faster the recommended cutting speed

90 The hardness of the cutting tool material has a great deal to do with the recommended cutting speed. The harder the cutting tool material, the faster the cutting speed. The softer the cutting tool material, the slower the recommended cutting speed

91 Calculating cutting speed Given in metres per minute spindle speed of machine (N) and diameter of work must be known S (m/min)= πdn/1000 Where π= 22/7 or D= diameter of material N= Spindle speed(rev/min) 47-91

92 Spindle Speed The rate at which the spindle rotates. It is commonly expressed in revolution per minute.

93 Calculating Spindle speed (rev/min) rev/min 1000 xs = π D S (m/min)= cutting speed Where π= 22/7 or D= diameter of material N= Spindle speed(rev/min

94 Examples Calculate rev/min required to drill a hole 15mm diameter in a piece of machine steel (CS 90) Find the cutting speed of a 10mm diameter drill with a spindle of 178 rev/min.

95 5. Find the cutting speed for: Diameter 9mm. Spindle speed 180rev/min Diameter 6mm. spindle speed 20rev/min Diameter 5mm. spindle speed 160rev/min spindle speed 120 rev/min. Diameter 10mm. 6. Find the spindle speed for: Diameter 16mm. Surface speed 20 m/min Diameter 14mm. Surface speed 30 m/min Diameter 15mm. Surface speed 15 m/min.