Drilling machine is one of the most important machine tools in a workshop. The basic parts of a drilling machine are a base, column, drill head and spindle. Explain operation, speeds and feeds of drilling machines. 5. Describe care and Check the drill tang for burrs and file it if necessary. • Sleeves get nicked when. Drilling machine. A Drilling machine at a construction site with a concrete pump and a barely visible concrete mixer. The tops of foundation columns with.
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1. UNIT 4: Drilling machines: Classification, constructional features, drilling & related operations, types of drill & drill bit nomenclature, drill materials. 6 Hrs. out by a rotating cutting tool to make circular holes in solid materials. Tool which makes hole is called as drill bit or twist drill. PURPOSE. This chapter contains basic information pertaining to drilling machines. A drilling machine comes in many shapes and sizes, from small hand- held.
Minor diameter of the thread is drilled and then tapping is done. The machine is driven by a small electric motor operating at high speed. Name some work holding devices? This is a light weight, high speed machine designed for drilling small holes in light jobs. What is countersinking?
This enables the operator to feel how the drill is cutting and accordingly he can control the down feed pressure. Sensitive drill presses are manufactured in bench or floor models, i. The base is a heavy casting that supports the machine structure; it provides rigid mounting for the column and stability for the machine.
The base is usually provided with holes and slots which help to Bolt the base to a table or bench and allow the work-holding device or the workpiece to be fastened to the base. The column is a vertical post that Column holds the worktable and the head containing the driving mechanism. The column may be of round or box section. The table, either rectangular or round.
The surface of the table is degree to the column and it can be raised, lowered and swiveled around it. Slots are provided in most tables to allow the jigs, fixtures or large workpieces to be securely fixed directly to the table. Drilling Head: The drilling head, mounted close to the top of the column, houses the driving arrangement and variable speed pulleys. These units transmit rotary motion at different speeds to the drill spindle.
The hand feed lever is used to control the vertical movement of the spindle sleeve and the cutting tool.
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Gundrills introduce coolant through a small hole within the tool. Gun drilling differs from BTA drilling due to the coolant entry and chip removal. Drilling is the operation of producing circular hole in the work-piece by using a rotating cutter called DRILL. BTA drilling becomes more effective than gundrilling around a 50mm hole diameter. BTA drilling has fluid enter through a mechanism around the tool. Multi-spindle 2 Based on Feed: Hand driven Power driven 8.
The head is bolted to the column. Hand Feed The hand. Column The column is cylindrical in shape and built rugged and solid. Sleeve The sleeve or quill assembly does not revolve but may slide in its bearing in a direction parallel to its axis.
These drilling machines can be bench or floor mounted. Feed pressure applied to the sleeve by hand or power causes the revolving drill to cut its way into the work a fraction of an mm per revolution.
Base The base of the drilling machine supports the entire machine and when bolted to the floor. The top of the base is similar to the worktable and may be equipped with t. It may be tilted up to 90 degree in either direction. Power feed The power feed drilling machine are usually larger and heavier than the hand feed ones they are equipped with the ability to feed the cutting tool in to the work automatically. Head The head of the drilling machine is composed of the sleeve. When the sleeve carrying the spindle with a cutting tool is lowered.
The column supports the head and the sleeve or quill assembly. Components of drilling machine Spindle The spindle holds the drill or cutting tools and revolves in a fixed position in a sleeve. The worktable can be adjusted vertically to accommodate different heights of work or it can be swung completely out of the way.
Worktable The worktable is supported on an arm mounted to the column. These are light duty machine that are operated by the operator. Vertical movement to the spindle is given by the feed handle by the operator. The table can also be swung to any desired position. Drill holes from 1. Operator senses the cutting action so sensitive drilling machine. A depth —stop mechanism is located on the head.
At the top of the column there are two pulleys connected by a belt. The vertical column carries a swiveling table the height of which can be adjusted according to the work piece height. Table can move vertically and radially.
The column and radial drilling machine supports the radial arm. Drill holes up to 50mm Fig.
Radial drilling machine belong to power feed type. This machine usually has a gear driven mechanism for different spindle speed and an automatic or power feed device. Feed can be either manual or automatic with reversal mechanism. A drill head may be moved on the arm manually or by power. Low cost 2. Drill Materials The two most common types are 1. TiN coated drills. The drill head is mounted on the radial arm and moves on the guide ways provided the radial arm can also be swiveled around the column.
HSS drill. The drill head is equipped with a separate motor to drive the spindle. By using drill sleeve By using drill socket By using drill chuck Boring is a process of enlarging an existing hole by a single point cutting tool. Boring operation is often preferred because we can correct hole size. Multi tooth cutting tool. Reaming is accurate way of sizing and finishing the pre-existing hole. This operation uses a pilot to guide the cutting action to accommodate the heads of bolts.
Special angled cone shaped enlargement at the end of the hole to accommodate the screws. Boring tool is held in the boring bar which has the shank. It is performed either by hand or by machine. Tapping is the process by which internal threads are formed. Minor diameter of the thread is drilled and then tapping is done.
Machine Table Vice The machine vice is equipped with jaws which clamps the work piece. The vice can be bolted to the drilling table or the tail can be swung around swung around. V-Blocks These are designed to hold round work pieces.. Common types of clamps are C-clamp. Parallel clamp. Step Blocks These are built to allow height adjustment for mounting the drilling jobs and are used with strap clamps and long T-slot bolts.
Clamps These are small. U-clamp etc. Jigs The jig guides the drill through a bushing to locate and drill holes accurately. Feed Rate f: Slots Bolt These are special bolts which has a T shaped head. Material Removal Rate: The cutting speed depends upon the properties of the material being drilled. Definitions 1. Cutting Speed v: Machining Time T: Depth of Cut d: The distance from the machined surface to the drill axis.
Calculate its taper angle. The dia of one end of a taper plug is mm and dia of the other end is 80mm and the length is mm. Never place tools on the drilling table Avoid loose clothing and protect the eyes.
Use brush to clean the chip No adjustments while the machine is operating Ensure for the cutting tools running straight before starting the operation. Problems 1. Calculate its taper. Machines should be cleaned after use Chips should be removed using brush.
Ease the feed if drill breaks inside the work piece. It depends upon the length l of the hole to be drilled. What is meant by reaming?
What is boring? Which tool is commonly used for drilling? What is meant by hand feed? Explain with neat sketch the salient features of radial drilling machine? Draw and explain the working principle of upright drilling machine? With neat sketch describe the nomenclature of twist drill? Name the different types of drilling machine?
A Multi spindle drilling machine has a number of drill spindles driven by a single motor. What is the difference between reaming and boring? What is meant by drilling? All the spindles holding the drills are fed in to the work piece at the same time.
What is the purpose of tapping operation? Name some work holding devices? Part — B 1. What are the different ways to mount the drilling tool? What is counter boring? For this purpose. What is meant by power feed? What is countersinking?
Review Questions: Part — A 1. Name the different types of drilling operations? Multi spindle drilling machines are employed for work of a light character.
What are the salient features of radial drilling machine? Drill bits can be fed by lowering the Drill head. The work pieces drilled in this machine are as follows: The Main eccentric is driven by the drilling machine spindle which is driven by a single motor. This machine is used in mass production. It is designed to drill five holes of various diameters in unsymmetrical layouts.
Eccentric is a mechanism which is usually used to convert rotary motion into sliding motion.