MACHINE TOOLS LECTURE NOTES 5 Working principles of drilling machine tool and its mechanism 1 DRILLING MACHINE TOOLS A drilling machine tool, called a drill press, is used to produce holes into or through workpiece material. Drill is held in the drilling machine by a chuck or Morse taper and is rotated and fed into the workpiece at variable speeds. DRILLING MACHINE TOOLS Drilling machines can perform various machining operations: Drilling, boring, core drilling, step drilling, counter sinking, boring, counter boring, spot facing, reaming and tapping. DRILLING MACHINE TOOLS DRILLING MACHINE TOOLS 1. Drilling Drilling is the operation of producing a circular hole in a solid metal by using a revolving tool is called as drill. The drill is multiple point cutting tool. DRILLING MACHINE TOOLS 2. Boring Boring is a process of enlarging a drilled hole by using an adjustable cutting tool called as boring tool. The boring operation is used to finish a drilled hole to accurate size and to correct the roughness of hole. DRILLING MACHINE TOOLS 3. Counter boring The operation which is used for enlarging only limited portion of the hole is called as counter boring and the tool used for this purpose is called as counter bore. DRILLING MACHINE TOOLS 4. Reaming Reaming is an operation of finishing already drilled hole. Material removal in reaming is negligible. The tool used for reaming operation is called as a reamer. DRILLING MACHINE TOOLS 5. Counter sinking Counter sinking operation is used for enlarging the end of the tool and give it a conical shape for a short length. The tool is used for this operation is called a counter sink. DRILLING MACHINE TOOLS 6. Tapping Tapping is the process of making threads in a drilled hole. The tool used for tapping is called a Tap. DRILLING MACHINE TOOLS Important parts: • Base • Column • Spindle • Sleeve (quill) • Head • Worktable DRILLING MACHINE TOOLS DRILLING MACHINE TOOLS Important Parts BASE The base supports the entire machine. It should be bolted to the floor. The top of the base is similar to a worktable and maybe equipped with T-slots for mounting workpiece too large for the table. DRILLING MACHINE TOOLS Important Parts COLUMN The column of most drill machines is circular and built rugged and solid. The column supports the head and the sleeve or quill assembly. DRILLING MACHINE TOOLS Important Parts SPINDLE The spindle holds the drill (cutting tool) and revolves in a fixed position in a sleeve. In most drilling machines, the spindle is vertical and work is supported on a horizontal table. DRILLING MACHINE TOOLS Important Parts SLEEVE (QUILL) The sleeve (quill) does not revolve but may slide in its bearing in a direction parallel to its axis. When the sleeve carrying the spindle with a cutting tool is lowered, the cutting tool is fed into the workpiece. When it is moved upward, the cutting tool is withdrawn from the workpiece. Feed pressure applied to the sleeve by hand or power causes the revolving drill to cut its way into the workpiece. DRILLING MACHINE TOOLS Important Parts HEAD The head of drill press is composed of the sleeve, spindle, electric motor and feed mechanism. The head is connected to the column. DRILLING MACHINE TOOLS Important Parts WORKTABLE The worktable is supported on an arm mounted to the column. The worktable can be adjusted vertically to accommodate different heights of workpiece. It may be swung completely out of the way. DRILLING MACHINE TOOLS Driving Mechanism Stepped type driving mechanisms are widely used. Stepless type driving mechanisms have found limited application according to drilling machine type (automatic feed mechanism) DRILLING MACHINE TOOLS Driving Mechanism DRILLING MACHINE TOOLS Driving Mechanism Belt Transmission DRILLING MACHINE TOOLS Driving Mechanism Pick-off Gear Mechanism DRILLING MACHINE TOOLS Classification 1. Bench-type sensitive drilling machines 2. Upright drilling machines 3. Radial drilling machines 4. Multi-spindle drilling machines 5. Special purpose drilling machines 6. Boring machines DRILLING MACHINE TOOLS Classification 1. BENCH-TYPE DRILLING MACHINES These drilling machines are used for machining small diameter holes of 0.25–12 mm diameter. Manual feeding characterizes this machine and that is why they are called “sensitive”. DRILLING MACHINE TOOLS Classification 2. UPRIGHT DRILLING MACHINES They are used for machining holes up to 50 mm in diameter in relatively small-size work. It has a wide range of spindle speed and feeds. Therefore, they are employed not only for drilling, but also core drilling, reaming, and tapping operations. DRILLING MACHINE TOOLS Classification 2. UPRIGHT DRILLING MACHINES DRILLING MACHINE TOOLS Classification 2. UPRIGHT DRILLING MACHINES 1- Table 2- Vertical drill spindle 3- Sleeve 4- Cone pulley 5- V-belt 6- Head 7- Driving motor 8- Vertical column 9- Base DRILLING MACHINE TOOLS Classification 2. UPRIGHT DRILLING MACHINES DRILLING MACHINE TOOLS Classification 2. UPRIGHT DRILLING MACHINES DRILLING MACHINE TOOLS Classification 3. RADIAL DRILLING MACHINES They are especially designed from drilling, counter boring, counter sinking, reaming and tapping holes in heavy and bulky workpieces that are inconvenient or impossible to machine on the upright drilling machines. They are suitable for multi-tool machining in individual and batch production. DRILLING MACHINE TOOLS Classification 3. RADIAL DRILLING MACHINES DRILLING MACHINE TOOLS Classification 3. RADIAL DRILLING MACHINES DRILLING MACHINE TOOLS Classification 3. RADIAL DRILLING MACHINES Based on the type and number of movements possible the radial drilling machine can be grouped as a) Plain radial drilling machine b) Semi-universal radial drilling machine c) Universal radial drilling machine DRILLING MACHINE TOOLS Classification 3. RADIAL DRILLING MACHINES a) Plain radial drilling machine In these type of machine three principle movements are possible i. Vertical movement of the arm along the column ii. Horizontal movement of the drill head along the column iii. Swinging movement of the arm in horizontal plane about the vertical column DRILLING MACHINE TOOLS Classification 3. RADIAL DRILLING MACHINES b) Semi-universal radial drilling machine In these type of machine in addition above three movements, the drill head can be swung about the horizontal axis which is normal to the arm. This fourth movement of the drill head enables drilling of holes at desired inclination with the normal vertical position. DRILLING MACHINE TOOLS Classification 3. RADIAL DRILLING MACHINES c) Universal radial drilling machine In these machine, the arm itself can be rotated through desired angle along horizontal axis. This is an addition to the four movement available on a semi-universal drilling machine. All these five movements in universal machine enable it to drill on the workpiece at any angle. DRILLING MACHINE TOOLS Classification 4. MULTI-SPINDLE DRILLING MACHINES They are mainly used in lot (mass) production for machining workpieces requiring simultaneous drilling, reaming and tapping of a large number of holes in different planes of the workpiece. A single spindle drilling machine is not economical for such purpose, as not only a considerably large number of machines and operators are required but also the machining cycle is longer. DRILLING MACHINE TOOLS Classification 4. MULTI-SPINDLE DRILLING MACHINES There are three types of multi-spindle drilling machines: a) Gang multi-spindle drilling machines b) Adjustable-center multi-spindle vertical drilling machines c) Unit-type multi-spindle drilling machines DRILLING MACHINE TOOLS Classification 4. MULTI-SPINDLE DRILLING MACHINES a) Gang multi-spindle drilling machines The spindles (2-6) are arranged in a row, and each spindle is driven by its own motor. The gang machine is in fact several upright drilling machines having a common base and single worktable. They are used for consecutive machining of different holes in one workpiece, or for the machining of a single hole with different cutting tools. DRILLING MACHINE TOOLS Classification 4. MULTI-SPINDLE DRILLING MACHINES a) Gang multi-spindle drilling machines DRILLING MACHINE TOOLS Classification 4. MULTI-SPINDLE DRILLING MACHINES a) Gang multi-spindle drilling machines DRILLING MACHINE TOOLS Classification 4. MULTI-SPINDLE DRILLING MACHINES a) Gang multi-spindle drilling machines DRILLING MACHINE TOOLS Classification 4. MULTI-SPINDLE DRILLING MACHINES b) Adjustable-center multi-spindle vertical drilling machines These differ from gang-type machines in that they have a common drive for all working spindles. The spindles are adjusted in the spindle head for drilling holes of varying diameters at random locations on the workpiece surface. DRILLING MACHINE TOOLS Classification 4. MULTI-SPINDLE DRILLING MACHINES b) Adjustable-center multi-spindle vertical drilling machines DRILLING MACHINE TOOLS Classification 4. MULTI-SPINDLE DRILLING MACHINES c) Unit-type multi-spindle drilling machines These are widely used in mass production. They are, as a rule, chiefly built of standard units. Such machines are designed for machining a definite component held in a jig and are frequently built into an automatic transfer machine. DRILLING MACHINE TOOLS Classification 4. MULTI-SPINDLE DRILLING MACHINES c) Unit-type multi-spindle drilling machines DRILLING MACHINE TOOLS Classification 5. SPECIAL PURPOSE DRILLING MACHINES Such machines are usually equipped with powerful pumps, which deliver cutting fluid under high pressure, either through the hollow drilling tool or through the clearance