MINOR PROJECT REPORTMULTI DRILLING MACHINE

Submitted in the partial fulfillment of the award of Degree in Mechanical Engineering

Of

KURUKSHETRA UNIVERSITY, KURUKSETRA, HARYANA STATE, INDIA

By

ROHIT SINGH - 3910606RAHUL SHARMA - 3910607SUKHDEEP SINGH - 3910631RAVI SINGH - 3910650

SUBMITTED TO

MECHANICAL DEPARTMENT

NOV, 2013

Modern Institute of Engineering and Technology

INTRODUCTION

MULTI SPINDLE DRILLING MACHINE

The MULTI SPINDLE DRILLING MACHINEis one which can be used to drill a number of holes at various large and even unsymmetrical layouts according to our requirements, where the conventional Multi spindle drilling machines cannot be used. This is an improvement over geared drill heads and drill heads adopted with universal joints. This is an improvement over geared drill heads and drill heads adopted with universal joints. The drill head is mounted on the drilling machine table.The drill head spindleis inserted into themachine spindle.It isusedto drillanumber ofholes indifferent layouts according deals with a proper idea of usage of eccentrics in the field of drilling. The report furnishes a cost estimation of all the components of the equipment by careful considerations of all factors such as cost of material, labour, machining and purchased components.

The very essence of our economic life and growth is dependent in a great part upon the continued improvement ofElectronic and Mechanical fields. To aidthese fields, we have designedMULTI SPINDLE DRILLINGMACHINEWhich can be widely used to drill products like printed Circuit Boards, Engine heads and otherAutomobile components. Extreme care should be there to drill multi holes at different layouts. TheMULTI SPINDLE DRILLING MACHINE helps to achieve accurate and identical drilled layouts in mass production.

Drill pressordrilling machineMachine toolfor producing holes in hard substances. Thedrillis held in a rotating spindle and is fed into the workpiece, which is usually clamped in avisesupported on a table. The drill may be gripped in a chuck with three jaws that move radially in unison, or it may have a tapered shank that fits into a tapered hole in the spindle. Means are provided for varying the spindle speed and (on some machines) for automatically feeding the drill into the workpieceDrilling Machinea machine for making holes with removal of chips. Drilling machines are used for drilling, boring, countersinking, reaming, and tapping. Several types are used in metalworking: vertical drilling machines, horizontal drilling machines, center-drilling machines, gang drilling machines, multiple-spindle drilling machines, and special-purpose drilling machines.Vertical drilling machines are the most widely used in metalworking. They are used to make holes in relatively small work-pieces in individual and small-lot production; they are also used in maintenance shops. The tool, such as a drill, countersink, or reamer, is fastened on a vertical spindle, and the work-piece is secured on the table of the machine. The axes of the tool and the hole to be drilled are aligned by moving the workpiece. Programmed control is also used to orient the workpiece and to automate the operation. Bench-mounted machines, usually of the single-spindle type, are used to make holes up to 12 mm in diameter, for instance, in instrument-making.Heavy and large workpieces and workpieces with holes located along a curved edge are worked on radial drilling machines. Here the axes of the tool and the hole to be drilled are aligned by moving the spindle relative to the stationary work-piece.Horizontal drilling machines are usually used to make deep holes, for instance, in axles, shafts, and gun barrels for firearms and artillery pieces.Center-drilling machines are used to drill centers in the ends of blanks. They are sometimes equipped with supports that can cut off the blank before centering, and in such cases they are called center-drilling machines. Gang drilling machines with more than one drill head are used to produce several holes at one time. Multiple-spindle drilling machines feature automation of the work process. Such machines can be assembled from several standardized, self-contained heads with electric motors and reduction gears that rotate the spindle and feed the head. There are one-, two-, and three-sided multiple-spindle drilling machines with vertical, horizontal, and inclined spindles for drilling and tapping. Several dozen such spindles may be mounted on a single machine. Special-purpose drilling machines, on which a limited range of operations is performed, are equipped with various automated devices.Multiple operations on workpieces are performed by various combination machines. These include one- and two-sided jig boring machines, drilling-tapping machines (usually gang drilling machines with reversible thread-cutting spindles), milling-type drilling machines and drilling-mortising machines used mainly for woodworking, and automatic drilling machines.D. L. IUDINIn woodworking much use is made of single- and multiple-spindle vertical drilling machines, one- and two-sided, horizontal drilling machines (usually with multiple spindles), and machines equipped with a swivel spindle that can be positioned vertically and horizontally. In addition to drilling holes, woodworking machines may be used to make grooves, recesses, and mortises and to remove knots.Multispindle drilling machine In these high production machine tools a large number of drills work simultaneously on a blank through a jig specially made for the particular job. The entire drilling head works repeatedly using the same jig for batch or lot production of a particular job. Fig. 4.2.8 shows a typical multispindle drilling machine. The rotation of the drills are derived from the main spindle and the central gear through a number of planetary gears in mesh with the central gear) and the corresponding flexible shafts. The positions of those parallel shafts holding the drills are adjusted depending upon the locations of the holes to be made on the job. Each shaft possesses a telescopic part and two universal joints at its ends to allow its change in length and orientation respectively for adjustment of location of the drills of varying size and length. In some heavy duty multispindle drilling machines, the work-table is raised to give feed motion instead of moving the heavy drilling head.

Fig. 4.2.8 A typical multi spindle drilling machine

The Gundrilling Machine

Specifically designed to provide the optimum conditions for operating the gun drill, the deep hole drilling machine is equipped with a high pressure pump that delivers lubricant to the rear of the drill. The drill can be driven by the spindle or held stationary if the workpiece is being rotated. During drilling, advancement can either be by drill or workpiece movement.

The gun drill is supported by anti-whip devices along the shank length and at the rear of the chip box. The chip box contains a chip deflector and a front end bushing which guides the drill into the workpiece. The chip box also contains escaping chips and lubricant, which are separated and filtered.

Gundrilling machines come in many variations, from single spindle manual models to CNC units with multiple spindles of different designs. They can be integrated into transfer lines or be part of a machining or turning center. Gun drilling is also becoming popular as a retrofit package for both conventional and CNC machines.

What Is Gun Drilling?Gun drilling is a process that produces deep, straight holes in a variety of materials. A gundrill tool differs from a conventional twist drill by its unique head geometry; a standard gundrill has a single effective cutting edge. Guide pads burnish the hole while drilling, allowing the hole to maintain straightness. The result of this burnishing activity is a very round hole with a precision diameter.

Gun drilling was initially developed for drilling gun barrels. Armament manufacturing continues to be a common use of this process. Other commonindustriesinclude energy, oil and gas exploration, engines, diesel fuel components, and plastic injection molds.Learn more, including the history of gun drilling, in our technical article from APMEN magazine.Holes deeper than 20:1 generally require a dedicated gundrilling machine to achieve highest productivity and process reliability.Gun drilling differs fromBTA drillingdue to the coolant entry and chip removal. Gundrills introduce coolant through a small hole within the tool, and chip removal occurs through a groove outside the tool. BTA drilling has fluid enter through a mechanism around the tool, while chips are evacuated through the drill itself. BTA drilling becomes more effective than gundrilling around a 50mm hole diameter.

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.

Drilling Machine

It is the simplest and accurate machine used in production shop.

The work piece is held stationary ie. Clamped in position and the drill rotates to make a hole.

Types

1) Based on construction:Portable, Sensitive,Radial, up-right,Gang, Multi-spindle

2) Based on Feed:Hand drivenPower driven

Components of drilling machine

SpindleThe spindle holds the drill or cutting tools and revolves in a fixed position in a sleeve.

SleeveThe sleeve or quill assembly 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 work: and when its moved upward, the cutting tool is withdrawn from the work. 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.

Column The column is cylindrical in shape and built rugged and solid. The column supports the head and the sleeve or quill assembly.

HeadThe head of the drilling machine is composed of the sleeve, a spindle, an electric motor and feed mechanism. The head is bolted to the column.

WorktableThe worktable is supported on an arm mounted to the column. The worktable can be adjusted vertically to accommodate different heights of work or it can be swung completely out of the way. It may be tilted up to 90 degree in either direction, to allow long pieces to be end or angle drilled.BaseThe base of the drilling machine supports the entire machine and when bolted to the floor, provides for vibration-free operation and best machining accuracy. The top of the base is similar to the worktable and may be equipped with t- slot for mounting work too larger for the table.

Hand Feed

The hand- feed drilling machines are the simplest and most common type of drilling machines in use today. These are light duty machine that are operated by the operator, using a feed handled, so that the operator is able to feel the action of the cutting tool as it cuts through the work piece. These drilling machines can be bench or floor mounted.

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, at preset depth of cut per revolution of the spindle these machines are used in maintenance for medium duty work or the work that uses large drills that require power feed larger work pieces are usually clamped directly to the table or base using t bolts and clamps by a small work places are held in a vise. A depth stop mechanism is located on the head, near the spindle, to aid in drilling to a precise depth.

Sensitive or Bench Drilling Machine

This type of drill machine is used for very light works. Fig.1 illustrates the sketch of sensitive drilling machine. The vertical column carries a swiveling table the height of which can be adjusted according to the work piece height. The table can also be swung to any desired position. At the top of the column there are two pulleys connected by a belt, one pulley is mounted on the motor shaft and other on the machine spindle. Vertical movement to the spindle is given by the feed handle by the operator. Operator senses the cutting action so sensitive drilling machine. Drill holes from 1.5 to 15mm

Fig.1. Sensitive Drilling Machine

Up-Right Drilling Machine

These are medium heavy duty machines. It specifically differs from sensitive drill in its weight, rigidity, application of power feed and wider range of spindle speed. Fig.2 shows the line sketch of up-right drilling machine. This machine usually has a gear driven mechanism for different spindle speed and an automatic or power feed device. Table can move vertically and radially. Drill holes up to 50mm

Fig.2 Up-Right Drilling Machine

Radial Drilling Machine

It the largest and most versatile used for drilling medium to large and heavy work pieces. Radial drilling machine belong to power feed type. The column and radial drilling machine supports the radial arm, drill head and motor. Fig.3 shows the line sketch of radial drilling machine.

Fig. 3 Radial Drilling Machine

The radial arm slides up and down on the column with the help of elevating screw provided on the side of the column, which is driven by a motor. 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. The drill head is equipped with a separate motor to drive the spindle, which carries the drill bit. A drill head may be moved on the arm manually or by power. Feed can be either manual or automatic with reversal mechanism.

Drill Materials

The two most common types are1. HSS drill- Low cost2. Carbide- tipped drills - high production and in CNC machines

Other types areSolid Carbide drill, TiN coated drills, carbide coated masonry drills, parabolic drills, split point drill. Fig.4 shows various types of drills

Fig. 4 Various types of drill

Drill fixed to the spindle

Fig. 5 Drill fixed to a spindle

Tool Nomenclature

Fig. 6 Nomenclature of twist drill

Tool holding devices

Fig.7 and Fig.8 shows the different work holding and drill drift device. 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

Drilling operations

Operations that can be performed in a drilling machine are

Drilling Reaming Boring Counter boring Countersinking Tapping

Drilling:

It is an operation by which holes are produced in solid metal by means of revolving tool called Drill. Fig. 9 shows the various operations on drilling machine.

Reaming:Reaming is accurate way of sizing and finishing the pre-existing hole. Multi tooth cutting tool. Accuracy of 0.005mm can be achieved

Boring: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, or alignment and can produce smooth finish. Boring tool is held in the boring bar which has the shank. Accuracy of 0.005mm can be achieved.

.Fig. 9 Various operations on drilling machine

Counter Bore :-

This operation uses a pilot to guide the cutting action to accommodate the heads of bolts. Fig. 10 illustrates the counter boring, countersunk and spot facing processes.

Countersink:-

Special angled cone shaped enlargement at the end of the hole to accommodate the screws. Cone angles of 60, 82, 90, 100, 110, 120

Fig. 10 Counter boring, countersunk and spot facing

Tapping:-

Tapping is the process by which internal threads are formed. It is performed either by hand or by machine. Minor diameter of the thread is drilled and then tapping is done. Fig. 11 show the tapping processes.

Fig. 11 Hand taps and tapping process using tap wrench

Fig. 12 Various operations performed on drilling machine

Work Holding Devices

1. Machine Table ViceThe 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. Fig. 13 shows the standard and swivel vice.The swivel vice is a machine wise that can be swivel through 360 on a horizontal plane.

Fig. 13 Machine Table vice.

2. Step BlocksThese are built to allow height adjustment for mounting the drilling jobs and are used with strap clamps and long T-slot bolts.

3. ClampsThese are small, portable vises , which bears against the work piece and holding devices. Common types of clamps are C-clamp, Parallel clamp, machine strap clamp, U-clamp etc.. Fig. 14 shows the correct and incorrect methods of mounting the work piece.

Fig. 14 Correct and incorrect methods of clamping the work piece.

4. V-BlocksThese are designed to hold round work pieces.

5. AnglesAngle plates are made in a 90angle with slots and bolt holes for securing work to the table.

6. JigsThe jig guides the drill through a bushing to locate and drill holes accurately.

7. T- Slots BoltThese are special bolts which has a T shaped head, which slides into the T slots of drilling machine work table.

Definitions

1. Cutting Speed (v):-

Its the peripheral speed of the drill.The cutting speed depends upon the properties of the material being drilled, drill material, drill diameter, rate of speed, coolant used etcv = *D*N whereD = dia of the drill in mN = Speed of rotation in rpm

2. Feed Rate (f):-

Its the movement of drill along the axis (rpm)

3. Depth of Cut (d):-The distance from the machined surface to the drill axis.d = D / 2

As the depth of hole increases, the chip ejection becomes more difficult and the fresh cutting fluid is not able to cutting zone. Hence for machining the lengthy hole special type of drill called gun drill is used.

4. Material Removal Rate:-

Its the volume of material removed by the drill per unit timeMRR = ( D2 / 4) * f * N mm3 / min

5. Machining Time (T) :-

It depends upon the length (l) of the hole to be drilled , to the Speed (N) and feed (f) of the drillt = L / f N min

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, and pulley should be cleaned. Machines should be lightly oiled to prevent from rusting

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.

Problems

1. Calculate the speed of the drill bit to drill a hole of dia 20mm where the cutting speed is 25mts/min.

N [rpm] = ( * D *N)/1000 = (25 * 1000) / ( * 20) = 397.8rpm

2. The dia of one end of a taper plug is 150mm and dia of the other end is 80mm and the length is 300mm. Calculate its taper.Taper per mm = (D-d)/L= (150-80)/ 300= 0.233mm3. . The dia of one end of a taper plug is 150mm and dia of the other end is 80mm and the length is 300mm. Calculate its taper angle.Tan /2= (D-d)/2 L = (150-80)/ 2*300= 6.65

Review Questions:

Part A

1. What is meant by drilling?2. Which tool is commonly used for drilling?3. Name the different types of drilling machine?4. What is meant by hand feed?5. What is meant by power feed?6. What are the salient features of radial drilling machine?7. What are the different ways to mount the drilling tool?8. Name the different types of drilling operations?9. What is meant by reaming?10. What is boring?11. What is the difference between reaming and boring?12. What is counter boring?13. What is countersinking?14. What is the purpose of tapping operation?15. Name some work holding devices?

Part B

1. Explain with neat sketch the salient features of radial drilling machine?2. Draw and explain the working principle of upright drilling machine?3. With neat sketch describe the nomenclature of twist drill?4. Discuss is detail with diagram the various operations that can be performed in drilling machine

WORKING PRINCIPLE

A Multi spindle drilling machine will drill a number of parallel holes simultaneously in a work piece. Multi spindle drilling machines are employed for work of a light character, especially repetition work, such as drilling small components for the Automobile and Aircraft industries. A Multi spindle drilling machine has a number of drill spindles driven by a single motor. All the spindles holding the drills are fed in to the work piece at the same time. For this purpose, either the drill heads can be lowered onto the work piece or the work table is raised.

The Main eccentric is driven by the drilling machine spindle which is driven by a single motor. The several drill holding eccentrics are driven by the main Eccentric through a Revolving plate. Eccentric is a mechanism which is usually used to convert rotary motion into sliding motion. It shall be noted that an Eccentric cannot convert reciprocating motion into rotary motion. Here we are converting the rotary motion into revolutionary motion and in to rotary motion. (ie) when the main spindle rotates, the rotary motion of the spindle is converted into revolutionary motion of the Revolving plate.

Through the Main Eccentric and the revolutionary motion of the Revolving plate is converted into rotary motion of the Drill holding Eccentrics. The conversion of the motion is achieved by the ECCENTRICITY provided in the eccentrics. [ECCENTRICITY is 15mm at all the eccentric spindles].Drill bits can be fed by lowering the Drill head. The pillars provided with springs guide the Driller head in motion. Springs secure the Drill head with drill bits, from a rapid fall, while releasing the Drill head from the machine spindle. It is designed to drill five holes of various diameters in unsymmetrical layouts. The art of ECCENTRICITY plays a major role in this principle.

APPLICATIONS

In this type of machine number of holes is drilled in the work piece at a time. This machine is used in mass production. The work pieces drilled in this machine are as follows:

Printed Circuit Boards. Pipe Flanges. Pump housings. Production works such as Drilling, Boring, Reaming and Tapping.

CONSTRUCTION

TAPER SHANK

DRILL CHUCK

SPUR GEAR

BOLT

WASHER

SPUR GEAR

NUT

PLATE24

Drilling And Drills
Types of drillsTwist drill: most common drillStep drill: produces holes of two or more different diametersCore drill: used to make an existing hole bigger

Drilling And Drills
Drilling operationsCounterboring & countersinking: produce depressions on the surface to accommodate the heads of screwsCenter drill: is a short and is used to produce the hole at the end of a piece of stockSpot drill: is used to spot (start) a hole at the desired locationGun Drilling - used fro drilling gun barrels and deep holesThrust Force and TorqueThrust force acts perpendicular to the hole axisCan cause the drill to bend or break if excessiveDrilling PracticeHeld in drill chuckswalking can be a problem when starting a holeThe drill should be guidedUsed a center drill to start a holeDrills can be reconditionedDrill life is measured by the number of holes drilled.

Drill point Geometries
Fig : Standard chisel-point drill indicating various features. The function of the pair of margins is to provide a bearing surface for the drill against walls of the hole as it penetrates into the workpiece; drills with four margins (double-margin) are available for improved drill guidance and accuracy. Drills with chip-breaker features are also available. (b) Crankshaft-point drill. (c) Various drill points and their manufacturers: 1. Four-facet split point, by komet of America. 2. SE point, by Hertel. 3.New point, by Mitsubishi materials. 4. Hosoipoint, by OSG Tap and Die. 5. Helical point.

Reaming And Reamers
Operation used to make an existing hole dimensionally more accurate than by drilling aloneThe hole making sequence isCenteringDrillingBoringreaming
Fig : various types of drilling and reaming operations.