Internship Report ISGEC

SETH JAĐ PRAKASH MUKAND LAL INSTĐTUTE OF ENGĐNEERĐNG & TECHNOLOGY

DEPARTMENT OF MECHANICAL ENGINEERING

INDUSTRIAL TRAINING REPORT

NAME-SURNAME

: Gumesh Rana.

DEPARTMENT

: MECHANĐCAL ENGĐNEERĐNG

CLASS / NUMBER

: ME-1209340

COURSE NAME COMPANY

: Mechanical Presses: Construction & Inspection : ISGEC Heavy Engineerings Limited(IHEL)

TRAINING PERIOD

: 6th July 2011 to 16th August 2011

TRAINING REPORT SETH JAĐ PRAKASH MUKAND LAL INSTĐTUTE OF ENGĐNEERĐNG & TECHNOLOGY DEPARTMENT OF MECHANICAL ENGINEERING

TRAINEE

Name and Surname Class ID Number

Gumesh Rana ME 1209340

INDUSTRIAL ORGANIZATION for TRAINING

Name Branch Department Address

ISGEC Yamuna Nagar MBD ISGEC, NH-73A, YNR

ORGANIZATIONAL ADMINISTRATORS

Managing Director Director Whole Time Director Chair Person

Mr. Aditya Puri Mr. Arun Kathpalia Mrs. Nina Puri Mr. Ranjit Puri

Table of contents Page no. Prologue

1

Acknowledgement

2

Chapter 1 ISGEC- A BRIEF PROFILE

3

Chapter 2 ISGEC- AN OVERVIEW

4

Chapter 3 PROJECT- CONSTRUCTION & INSPECTION OF PRESSES 3.1 Preparation Shop

8 8

3.2 Fabrication Shop 3.2.1 Instructions for various works in Fabrication Shop 3.2.2 Welding Techniques Observed

8 9 14

3.3 Machine Shop

19

3.4 Assembly Shop

19

Chapter 4 MECHANICAL PRESS 4.1 Principle

21 21

4.2 Advantages

21

4.3 Features of Mechanical Press

21

4.4 Problems in Mechanical Press

24

4.5 Inspection of Presses

25

PROLOGUE Practical knowledge means the visualization of the knowledge, which we read in our books. For this, we perform experiments and get observations. Practical knowledge is very important in every field. One must be familiar with the problems related to that field so that he may solve them and become a successful person. After achieving the proper goal in life, an engineer has to enter in professional life. According to this life, he has to serve an industry, may be public or private sector or self-own. For the efficient work in the field, he must be well aware of the practical knowledge as well as theoretical knowledge. To be a good engineer, one must be aware of the industrial environment and must know about management, working in the industry, labor problems etc. so he can tackle them successfully. Due to all the above reasons and to bridge the gap between theory and practical, our engineering curriculum provides a practical training of 6 weeks. During this period, a student works in the industry and gets all type of experience and knowledge about the working and maintenance of various types of machinery. I have undergone my summer training (after 2nd yr.) at ISGEC HEAVY ENGINEERINGS LIMITED. This report is based on the knowledge, which I acquired during my training period at the plant.

Gumesh Rana 09-ME-340

1

ACKNOWLEDGEMENT With a sense of great pleasure and satisfaction I present this industrial training report. Completion of this report is no doubt a product of invaluable support and contribution of a number of people. I present my sincere gratitude to my father MR. V.S. Rana (Sr. Mngr. MBD Planning), Mr. Rajendra Agnihotry (Head, Training & Development), MR. Dhamender Sharma (PVD-QA), Mr. Bharti (Head, Preparation shop) of ISGEC for being a constant guide, inspiration and a source of illumination throughout this entire period. Without their support this would not have been possible.

Gumesh Rana 09-ME-340

2

Chapter 1 ISGEC-A BRIEF PROFILE ISGEC (formally Indian Sugar and General Engineering Corporation) is an Indian multinational boilers, Process plant, Sugar plant and agricultural equipment company headquartered in Noida, India. It is one of Asia's largest Sugar Plant Machinery producers. It produces various types of machines, including boilers, Steel casting, Presses and Sugar Machinery. It has its manufacturing unit in Yamunanagar, Noida, Muzaffarnagar, Dahej and its products are sold in over 66 countries. •

ISGEC has been approved by Lloyds Register Asia (LRA) of quality assurance as an ISO-9001: 2000 company.

•

The American Society of Mechanical Engineers (ASME) approves ISGEC for the use of ASME ‘U’, ‘U2’, R & S code stamps.

•

Lloyds Register Asia as class-I Manufacturing of Fusion welded pressure vessels approves ISGEC up to 200 mm thickness.

•

Engineers India Ltd. (EIL) approves ISGEC for Manufacture of vessels and columns in carbon and alloy steels up to 155mm thickness and in clad steel up to thickness of 130mm.

•

Engineers India Ltd. approves ISGEC for Manufacture of Heat Exchangers up to maximum tube sheet thickness of 300mm.

3

Chapter 2 ISGEC-AN OVERVIEW ISGEC the heavy engineering unit of Saraswati industrial ltd. was established in 1946 and is located at Yamunangar, Haryana about 200kms from New Delhi. The annual turnover of ISGEC is US $ 50 million and group turnover of the Saraswati Industial Syndicate ltd. Exceeds US $ 100 million.


Infrastructure •

Lifting Capacity : Crane capacity- 200 MT (Hydraulic Lifting arrangement for heavier loads up to 250 MT)

•

Shop covered area: 43,000 Sq. Meter (51,427 Sq. yards)

•

Total plant area: 250,000 Sq. Meter (298,998 Sq. yards)


Forming •

Rolling : Thickness - 200 mm (8 inches)


Welding •

Narrow Gap Welding with seam tracking

•

Strip Cladding using single as well as double layer technique

•

Automatic small diameter nozzle cladding.

•

Twin wire and tandem head welding SAW, SMAW, TIG, and MIG etc. Over 850 WPS and 1000 PQR


Drilling •

Thickness up to 1000 mm ( 40 inches) using deep hole CNC Drilling machine

4


Heat Treatment •

Four Gas Fired Furnaces Size upto: 4500 mm x 4000 mm x 14500 mm

•

Stress Relieving, Annealing, Quenching and Tempering as well as Solution Annealing of Stainless Steels

•

Local Stress Relieving by Electrical Resistance Method

•

Stress Relieving by Internal Firing Method

•

Stress Relieving of large jobs in Temporary Furnaces


Radiography •

Cobalt 60 for Radiography up to 200 mm (8 inches)


Testing •

Tensile testing including Elevated Temperature Testing up to 8000 C (14700 F)

•

Impact Testing up to (-) 1960 C (-3200 F)

•

Insitu Alloy Analyzer

•

Metallurgical Microscope X-2000 with Photography facility

•

Ferrite Measurement

•

Recordable/ Mechanized Ultrasonic Testing

•

Magnetic particle Testing

•

Liquid Penetrant Testing

•

Holiday Testing for Painting

•

IGC Testing

•

Complete laboratory supported by spectrometer

5

PRODUCT RANGE Diversity of ISGEC products range enables us to serve industry from Automobile and ship building to oil & natural gas, defense, aeronautics and nuclear power. The group’s product range includes for; •

Hydraulic Presses, Mechanical Presses & Press brake. ISGEC has successfully commissioned around 100 presses built include a 3700 tones hydraulic presses for defense and a 2500 tones mechanical press.

•

Process plant equipment (pressure vessels, heat exchangers, columns, storage and transport vessels, reactors etc.) for fertilizer refinery, petrochemical and other industries.

•

Industrial & power boilers(including pulverized fuel boilers up to 60 MW size bubbling as well as circulating fluidized bed boilers up 200 TPH size).

•

Custom made equipment for India’s nuclear establishments. ISGEC has supplied equipment during last 15 years to Bhabha Atomic Research Center, Nuclear power Corporation, center of advanced technology.

•

Chlorine, Ammonia and other gases containers. ISGEC are the largest manufactures of chlorine in the world.

6

DIVISION OF ISGEC The various divisions of ISGEC are as follows;

1. PRESSURE VESSEL DIVISION (PVD) Pressure vessel division is the oldest of ISGEC and it manufactures pressure vessels such as boilers, heat exchangers etc. It is sub-divided into following shops; •

PVD-I

•

PVD-II

•

PVD-III

•

PVD-IV

2. MACHINE BUILDING DIVISION (MBD) Machine building division is very important division of ISGEC and it manufactures sugar mill machinery. Press components and other Steel plant machinery. It is sub-divided into following shops; •

FABRICATION SHOP-I,II

•

MACHINE SHOP-I,II

•

ASSEMBLY SHOP

• QUALITY SHOP 3. FOUNDRY GROUP (FG) Foundry group is the third important group of ISGEC and it is responsible for casting of large castings for the big industries.

4. TUBE SHOP Tube shop deals with tube manipulation and fabrication of tubing system used in economizers and superheaters.

5. CONTAINER SHOP Container shop manufactures chlorine, ammonia and other gases containers.

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Chapter 3 PROJECT- CONSTRUCTION & INSPECTION OF PRESSES The step by step procedure followed during the project & explanation of the same is as follows;

3.1Preparation Shop This is where the raw material for production is brought in initial stage and it is identified as per the specification. The scope of Preparation shop is to prepare material required by various other shops. The tentative load or the amount of material required is set in starting of the financial year i.e. October. The quantity depends upon the delivery date & the requirement of the customer, The raw material is firstly identified & then is brought inside the shop where cutting operations are performed by using manual Gas cutting & CNC machines on the material as per requirement for its fabrication. The two main requirements for cutting the material are drawing, and information about material. The cutting machines are CNC which require some operator to feed the program and the cutting is done as per the program. Most of the programs are made by the operators while some complex programs are made by supervisors. The programs are compiled in AutoCad & are feed directly to CNC through Burney LCD scanner. There are two cutting methods A) Gas cutting A cutting torch is used to heat metal to kindling temperature. A stream of oxygen is then trained on the metal, and metal burns in that oxygen and then flows out of the cut as an oxide slag. B) Plasma cutting An inert gas is blown at high speed out of a nozzle; at the same time an electrical arc is formed through that gas from the nozzle to the surface being cut, turning some of that gas to plasma. The plasma is sufficiently hot to melt the metal being cut and moves sufficiently fast to blow molten metal away from the cut.

3.2Fabrication Shop Fabrication shop is one of the constituents of the machine-building division. Almost all sort of fabrication work are done here. In this shop thick sheets of mild steel are cut, welded and bent according to the required design. For the cutting of plates and sheets gas cutting technique is made use of. Then different cut parts are joined together with the help of welding.

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Some of the welding techniques adopted are • Gas Metal Arc Welding (GMAW) • Submerged Arc Welding (SAW) • Shielded Metal Arc Welding (SMAW) • Semi Saw • Plasma Arc Welding The bending of sheets is preferred in hydraulic presses. For bending, a specific type and size of the die is kept under the plate to be bent and then hydraulic pressure is applied above the plate. Extent of bending depends upon the radius of curvature of arc formed by bend plate. Gouging is used for repairing faulty weld joint.

3.2.1 Instructions for various works in Fabrication Shop • Gas Cutting Instructions 1. Select the optimum plasma cutting machine as per the supervisor’s instructions. 2. Read instructions and work method on machine. 3. If cutting is through gauging, then leave 1.5mm from marking punch & start cutting.

General Instructions 1. Clean the surface before cut. 2. Cut in down hand position only. 3. Use guide in case of round cutting (whenever possible). 4. Use cookie machine during straight cut. 5. Avoid under cuts during cutting. 6. Ask supervisor in case of any doubt.

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Width in mm

Size of nozzle in inch

Oxygen pressure in

Acetylene pressure in

kg/cm2

kg/cm2

2-6

1/32

1

0.2

7-12

3/64

1.5

0.5

14-40

1/16

2.5

0.5

45-56

5/64

3.5

0.5

63-80

3/32

5.0

0.5

100-150

1/8

6.0

0.5

200-300

1/8

9.0

0.5

Table 3.1 Specifications as per width of sheet to be cut

• Cold Bending 1. Check machine and dye as per requirement. 2. Check material size and mark bend line as per layout. 3. Set dye as per the material size. 4. After setting up machine, set bend marking and bend degree. 5. Bend the job slowly and on completion check the size with the help of template. 6. Check the completed piece and get it passed by supervisor.

• Fitting via Welding 1. Check material according to BOM. 2. Collect drawing from supervisor and required material from BOM. 3. Check the material for straightness. 4. Straight material as per supervisor’s instructions. 5. Prepare layout for fitting as per drawing and supervisor. 6. Set priorities for fitting as per supervisor’s instructions and drawing or ND table given by Quality Assurance. 10

7. Fit job as per drawing or layout. 8. Mark job no., drawing no., mark no., serial no., and fabrication weight which must not exceed 5 tons, 9. Self-inspect for next operation.

• Painting a Job 1. Collect required information about job from supervisor. 2. Check for rust, oil or grease or any kind of dust material on job. 3. Before painting, check that job is grit blast or wire brushed as per job drawing. 4. Clean job surface as required by piece of cloth. 5. Apply primer as per Quality Assurance or instructions. 6. Ask supervisor in case of any doubt.

• Hydro-testing 1. According to supervisor’s instructions, set job’s position keeping in mind the position of air packet. 2. Collect at least 2 pressure gauges as per the test pressure given in job drawing, 3. Range of pressure gauge must be between 1.5-4 times the test pressure. 4. Gauges must be calibrated. 5. Gauge must be placed at a place from where its reading is easy to read. 6. Tight all gauges and close all job openings before applying pressure. 7. Apply test pressure as per supervisor’s instructions and check for leakage and report the same. 8. Remove pressure slowly and remove water from job completely.

9. If there is a difference of more than 30PSI, than report to the supervisor. • Welding 1. Collect information about the job and type of welding from supervisor. 2. Select appropriate machine and check for its calibration and connections. 3. Check WPS or shop welding record of job and check for your qualified position. 4. Collect electrode from electrode cabin as per data sheet.

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5. Issue a maximum of 15 electrode and filler wire for MIG/TIG. 6. Weld according to WPS and test Route run OP of 10% part of groove size more than 10mm. 7. Return stubs of used electrodes before issuing new electrodes.

8. Self-inspect after welding and fill up check sheet. • Blast Cleaning Stage I 1. Clean job from grease, oil, etc. 2. Blast job as per SA 2 ½ Swedish standard SIS055900. Check surface profile by comparing it with standard full size photograph. 3. If blast cleaning is not possible, clean grease with the help of D-slagging gun or Wire brush. 4. Get the job checked by Shop supervisor,

Stage II Primer coating inside oil tank 1. Before applying primer check that it has been not more than 8hrs after blasting. 2. Job must be properly cleaned and dry. Never clean with the help of a cloth. 3. Keep in mind following things before applying primer; 4. Use primer epoxy Zinc Chromate only, and ensure that it’s not more than 12 months old. 5. Ensure primer is in 2 packs and mix its plate and hardener as per instructions below. A. For mixing Zinc Chromate use 3 parts of paste and 1 part of hardener, use epoxy thinner to dilute the paste. Pot life for such a primer is 3-4hrs use brush or spray gun to apply primer. B. Keep in mind the time required by primer to dry. For Touch dry it is 1hr. For Handle dry is 4hrs. And hard dry is 12hrs.

For Steel Structure Same as for Oil tank above, except the use of Zinc Phosphate primer.

Stage III, IV & V Painting top coat 1. Ensure condition of primer coating before applying Putty.

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2. Rough the primered surface with emery paper and clean dry with the help of cloth. 3. Each outer surface of job that is visible and is primered is coated with a layer of Putt. For the same, Putty is prepared as below; 4. Take 9 parts paste and 1 part hardener. Use epoxy thinner to dilute the mixture. Stir a rod or stirrer. Pot life is of 3-4hrs. 5. Apply the prepared Putty with the help of knife. Dents are filled up with the help of Putty. It takes 12hrs to dry. 6. Use Putty Sander for rubbing of Putty as per given below; 7. If drying time is 14-24hrs use 80 Grit Sanding disc on Putty sander. If drying time is more than 24hrs then use 60 Grit Sanding disc. 8. Clean with a clean cloth. 9. Cover the entire machined surface with PVC tape, Grease, Oil, etc. 10. Apply a coat of surfacer. Keeping in mind the following points; 11. Use PU surface only and use 9 parts with 1parts Hardener and prepare that much only which can be utilized within 4-6hrs. Give at least 4hrs after applying to dry.

Stage VI and VII 1. Apply on jobs ready to be dispatch. 2. Ensure the job free from any kind of dust particles, if so, clean the surface with help of surface thinner, 3. Use primer on grinded surface. 4. Use epoxy Putty on scratched surface and give time to dry. 5. Cover all those surfacers that are not to be painted. 6. Use 80 Grit Sanding disc in sander and plane those surfaces where putty is applied. 7. Use PU surface on surfaces where Putty is applied. 8. Use paint where PU surface has been applied and give paint time to dry. 9. Now apply a fixed coat of paint. 10. Use rust guard on all machined surfaces. 11. Use Zinc phosphate primer on inside parts and those parts that touch ground.

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12.Uncover all the parts and clean them properly.

3.2.2 Welding Techniques Observed 3.2.2.1

Submerged Arc Welding (SAW)

It is a common arc welding process. It requires a continuously fed consumable solid or tubular (flux cored) electrode. The molten weld and the arc zone are protected from atmospheric contamination by being submerged under a blanket of granular fusible flux consisting of lime, silica, manganese oxide, calcium fluoride, and other compounds. When molten, the flux becomes conductive, and provides a current path between the electrode and the work. This thick layer of flux completely covers the molten metal thus preventing spatter and sparks as well as suppressing the intense ultraviolet radiation and fumes that are a part of the process.

Fig. 3.1 A schematic diagram of submerged arc welding SAW is normally operated in the automatic or mechanized mode. The process is normally limited to the flat or horizontal-fillet welding positions.

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Fig. 3.2 Pieces of slag from Submerged arc welding

Electrode SAW filler material usually is a standard wire as well as other special forms. This wire normally has a thickness of 1/16 in. to 1/4 in. (1.6 mm to 6 mm).

Factors that usually effect SAW 1. Wire feed speed (main factor in welding current control) 2. Arc voltage 3. Travel speed 4. Electrode stick-out (ESO) or contact tip to work (CTTW) 5. Polarity and current type (AC or DC) & variable balance AC current Weld Layer

Electrode Size

Current (A)

Voltage (V)

Speed (IPM)

Root

4.00mm

140-160

22-24

16-18

Subsequent

4.00mm

400-500

28-32

18-24

Lapping

4.00mm

500-600

32-34

18-24

Table 3.2 Specifications as per Weld Layer

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Advantages 1. High operating factors in mechanized applications. 2. Deep weld penetration. 3. Sound welds are readily made (with good process design and control). 4. High speed welding of thin sheet steels up to 5 m/min (16 ft/min) is possible. 5. Minimal welding fume or arc light is emitted. 6. Practically no edge preparation is necessary. 7. The process is suitable for both indoor and outdoor works. 8. Distortion is much less. 9. Welds produced are sound, uniform, ductile, corrosion resistant and have good impact value. 10. Single pass welds can be made in thick plates with normal equipment. 11. The arc is always covered under a blanket of flux, thus there is no chance of spatter of weld. 12. 50% to 90% of the flux is recoverable

Limitations 1. Limited to ferrous (steel or stainless steels) and some nickel based alloys. 2. Normally limited to long straight seams or rotated pipes or vessels. 3. Requires relatively troublesome flux handling systems. 4. Flux and slag residue can present a health & safety concern. 5. Requires inter-pass and post weld slag removal.

3.2.2.2

Gas Metal Arc Welding

Sometimes referred to by its subtypes metal inert gas (MIG) welding or metal active gas (MAG) welding, is a semi-automatic or automatic arc welding process in which a continuous and consumable wire electrode and a shielding gas are fed through a welding gun. A constant voltage, direct current power source is most commonly used with GMAW, but constant current systems, as well as alternating current, can be used. There are four primary methods of metal transfer in GMAW, called globular, short-circuiting, spray, and pulsed-spray, each of which has distinct properties and corresponding advantages and limitations.

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Fig. 3.3 GMAW Circuit diagram. (1) Welding torch, (2) Workpiece, (3) Power source, (4) Wire feed unit, (5) Electrode source, (6) Shielding gas supply

Equipment Welding gun The typical GMAW welding gun has a number of key parts—a control switch, a contact tip, a power cable, a gas nozzle, an electrode conduit and liner, and a gas hose. The control switch, or trigger, when pressed by the operator, initiates the wire feed, electric power, and the shielding gas flow, causing an electric arc to be struck. The contact tip, normally made of copper and sometimes chemically treated to reduce spatter, is connected to the welding power source through the power cable and transmits the electrical energy to the electrode while directing it to the weld area. The gas nozzle is used to evenly direct the shielding gas into the welding zone—if the flow is inconsistent, it may not provide adequate protection of the weld area.

Fig. 3.4 GMAW torch nozzle cutaway image. (1) Torch handle, (2) Molded phenolic dielectric (shown in white) and threaded metal nut insert (yellow), (3) Shielding gas diffuser, (4) Contact tip, (5) Nozzle output face

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Wire feed unit The wire feed unit supplies the electrode to the work, driving it through the conduit and on to the contact tip. Most models provide the wire at a constant feed rate, but more advanced machines can vary the feed rate in response to the arc length and voltage.

Electrode Electrode selection is based primarily on the composition of the metal being welded, the process variation being used, joint design and the material surface conditions. All commercially available electrodes contain deoxidizing metals such as silicon, manganese, titanium and aluminum in small percentages to help prevent oxygen porosity. Some contain denitriding metals such as titanium and zirconium to avoid nitrogen porosity. Depending on the process variation and base material being welded the diameters of the electrodes used range from 0.7 to 2.4 mm but can be as large as 4 mm.

Shielding gas Shielding gases are necessary for gas metal arc welding to protect the welding area from atmospheric gases such as nitrogen and oxygen, which can cause fusion defects, porosity, and weld metal embrittlement if they come in contact with the electrode, the arc, or the welding metal. The choice of a shielding gas depends on several factors, most importantly the type of material being welded and the process variation being used. Pure inert gases such as argon and helium are only used for nonferrous welding; with steel they do not provide adequate weld penetration (argon) or cause an erratic arc and encourage spatter (with helium).Pure carbon dioxide, on the other hand, allows for deep penetration welds but encourages oxide formation, which adversely affect the mechanical properties of the weld. Its low cost makes it an attractive choice, but because of the reactivity of the arc plasma, spatter is unavoidable and welding thin materials is difficult. As a result, argon and carbon dioxide are frequently mixed in a 75%/25% to 90%/10% mixture. Shielding gas mixtures of three or more gases are also available. Mixtures of argon, carbon dioxide and oxygen are marketed for welding steels. Other mixtures add a small amount of helium to argon-oxygen combinations, these mixtures are claimed to allow higher arc voltages and welding speed.

Advantages 1. Because of continuously fed electrode, MIG welding process is much faster as compared to TIG or stick electrode welding. 2. It can produce joints with deep penetration. 3. Thick and thin, both types of work pieces can be welded effectively. 4. Large metal deposition rates are achieved by MIG welding process. 5. The process can be easily mechanized. 6. No flux is used. MIG welding produces smooth, neat, clean and spatter free welded surfaces which require no further cleaning. This helps reducing total welding cost.

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7. Higher arc travel speeds associated with MIG welding reduce distortion considerably.

Disadvantages 1. The process is slightly more complex as compared to TIG or stick electrode welding because a number of variables (like electrode stick out, torch angle, welding parameters, type and size of electrode, welding torch manipulation, etc.) are required to be controlled effectively to achieve good results. 2. Welding equipment is more complex, more costly and less portable. 3. Since air drafts may disperse the shielding gas, MIG welding may not work well in outdoor welding applications. 4. Weld metal cooling rates are higher than with the processes that deposit slag over the weld metal.

3.3 Machine Shop Machine shop is the main work station. Here various machining operations are carried out to produce different parts of presses. There are two division of machine shop a) Machine shop-I Heavy Work Division b) Machine shop-II Light Work Division Various Machine Employed at Machine Shop-I 1. SKODA horizontal boring HB -11, HB-3, HB-19, HB-8, HB-1 2. SWIFT Lathe ML-14 3. H.M.T Radial Drilling Machine RD-4 4. SACEM- MSMG

3.4 Assembly Shop The last stage in the machine building division, the various components for the construction of a press is collected here and the final assembly of the press is done. The shop is divided in two zones of area one is the pit area and the other is outer area. Presses greater in size and height are assembled in the outer area and those normal in size in the pit area. The final assembly involves very precise work and therefore requires more skilled workers and experienced supervisors. Each press is assembled according to the requirement of the customer. The assembly requires two broad machine parts 19

•

Parts fabricated by ISGEC i.e. the frame and some other components.

•

Parts being imported from outside that are parts like modules and brake and gear system and oil lubrication unit.

The link frame presses are assembled with the help of tie rods which join the bottom head, uprights and top head together. The tie rod helps to assemble them in proper positions. When the frame is ready the slide is moved inside it and placed with the help of jigs etc. all other parts are assembled as per requirement with the help of drawing. Once the press is complete it is tested again and again for any kind of defect before it is dispatched. The assembly is a complex process and involves hours of continues work the steps involved are discussed below 1. Gathering all the required material for the construction. 2. Identifying the various parts and their layout. 3. Inspecting all material and its reliability. 4. Starting the assembly work as per the requirement. 5. After the assembly is over each part is punched of marked for identification and for making the work of site workers easy. 6. After assembly the presses are tested for any fault and any faulty material is either removed or corrected. 7. After the inspection is over the press is dismantled and is ready to be dispatched.

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Chapter 4 MECHANICAL PRESS 4.1 Principle The power is transmitted from motor to flywheel with the help of flat or V-belt. Most commonly V-belt is used because in case of flat belt, losses due to slip are present. When clutch are not engaged with the flywheel drive shaft does no rotate. When air is supplied to the clutch brake assembly then at a particular pressure of air, the liner of clutch-brake engages with flywheel and drive shafts starts rotating. There are teeth cut on the other end of the shaft, which mesh with the larger gear mounted on the eccentric shaft. So when pinion shaft rotates, the motion is transferred to the eccentric shaft through connecting rod or pitman, which is mounted on the eccentric part of the shaft. In this way, rotating motion of the motor is converted in to reciprocation motion of the slide.

Fig, 4.1 Mechanical presses at ISGEC

4.2 Advantages •

Faster production rate than hydraulic press.

•

Ease of maintenance.

•

Suitable for operation viz. punching, blanking and trimming in which there is sudden release of load at the end of cutting stroke.

•

Ease of interfacing with automatically material handling systems.

•

Press over loading is possible. Safe guard against over load is required.

4.3 Features of Mechanical Press 4.3.1 Die Cushion A large pressurized cylinder located in or under a die block or bolster to provide additional pressure or motion for stamping.

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Need for a Die Cushion 1. To prevent slip and wrinkling during forming from a blank. 2. Uniform pressure over entire blank. 3. Uniform pressure throughout entire stroke. 4. Easy adjustment with changing jobs. Two kinds of die cushions are used Pneumatic Hydro-Pneumatic The pneumatic die cushion is mostly widely used. Standard air pressure in a pneumatic die cushion is 45kg/cm2. When it is necessary to raise the pressure in a pneumatic die cushion up to three cylinders can be used in tandem. A hydro-pneumatic die cushion can only be used for a single stage. The blank holder pressure and knock out pressure are the same in the pneumatic die cushion; however, in a hydro pneumatic die cushion the knock out pressure is only about one sixth of the blank holder pressure. 4.3.2 Clutches and Brakes Mechanical press uses clutch and brake assembly. Electric brake and clutch assemblies are equipment drive components that consist of electric brakes for slowing or stopping shafts and electric clutches for connecting or disconnecting shafts. Engaging the clutch transfers power from an engine to devices such as a transmission and drive wheels. Disengaging the clutch stops the power transfer, but allows the engine to continue turning. Braking slows or stops the movement of the coupled shafts by using permanent magnets, hysteresis, and eddy current or magnetic particles. All the mechanical presses are provided with a flywheel to store energy. During the idle position of the stroke, flywheel rotates continuously on the main shaft and power to slide is transmitted through a clutch. Clutches are of positive friction and eddy current types. A brake is an important part of a press. It assists the clutch thereby ensuring positive and safe operation of the press. A faulty brake can cause a major break down of the press. When the press starts the clutch must engage only after the brake has been released and conversely, when the press stops the brake must operate only after the clutch has been disengaged, the time lapse in each case is called time lag. The control of provided clutches is usually limited to stop and start only. Mechanical controls are available so that the press cycle may be either continuous. This clutch has many other special features to be designed in to the system to suit almost any circumstances.

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4.3.3 Various Modes of Run Inch mode Inch controls is mainly used for setting up the tools and allows the press to run only when inch button is pressed. When inch button is released press stops. It is the most common mode of operation.

Single auto mode In this mode press run one complete cycle.

Continuous mode In this mode press run for predefined number of cycles. The press must be equipped with automatic feeder. 4.3.4 Slide Adjuster A slide adjuster is used to adjust the position of the bottom face of the slide to change the die height. Adjustments are made by turning the threaded coupling part between the connecting rod and slide. Generally on small capacity presses adjustments are made manually with a turning rod and other suitable tool. For medium and large capacity presses, however, this is done with an electric and air motor. 4.3.5 Counter Balance Cylinders The weight of the slide is generally 5-20 tones, which is acting in downward directing, so during the upward motion of the press the weight is against the mechanical force. So, power requirement during downward stroke is very low and during the upward stroke the power requirement is very high. So motor with large range is required which is impractical. To avoid this difficulty the slide is kept in equilibrium position i.e. weight of slide is required to zero. For this purpose counter balance cylinders are used. The counter balance cylinders are mounted on both sides of the slide. Each cylinder consists of a piston fitted with a piston rod. The other end of the piston rod is connected to slide. As the area of cylinder is fixed the pressure of air inside the cylinder is changed to meet the equilibrium condition. The air is supplied to the cylinder is changed through an air tank whereas air tank receives air at high pressure by a pneumatic pump. The counter balance cylinder is fitted with a spring loaded valve and a pressure switch. When counter balance tank exceeds certain permissible value then the valve opens and excess air leaves the tank. Similarly pressure switch also protects the tank from over pressure. When pressure exceeds permissible value pressure switches controls and press stops working. 4.3.6 Knockout Device A knockout device is used at the conclusion of a forming process to separate the formed product from the die. There are three types of knockout devices Mechanical Pneumatic Hydraulic

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A knockout device is normally fitted to the slide of the press, however, in a forging press it is fitted to the head size. 4.3.7 Flywheel Brake When the main motor power of a medium or a large capacity press is cut off, the flywheel continues to turn for a considerable time under its own inertia. To stop the flywheel the brake is engaged directly to flywheel rim.

4.4 Problems in Mechanical Press 4.4.1 Bottom Head The common problem is with leveling, and can be cured by using a calibrated master level. Self-calibration of Master level is done as follows; Place on any surface such that bubble is in between two braces. Rotate through 1800, & check it again. If the reading is same then its accurate.

4.4.2 Slide •

Pump taking continuous stroke, check for; leakage from any pipe. porosity during welding. internal leakage.

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Adjustment motor drawing high current.

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Abnormal sound during adjustment.

4.4.3 Upright •

Sitting problem occur due to machining inaccuracy.

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Taper matching problem.

4.4.4 Gear Train •

Key way mismatching.

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Geometrical inaccuracy in bores.

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Timing error

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Fouling of connecting rod.

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Noise level is high.

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Backlash, Back biting & abnormal heating.

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4.4.5 Crown •

Abnormal heating of motor.

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Uneven tension in belt.

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Leakage from flywheel.

4.4.6 Power pack •

Abnormal sound.

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No pumping.

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Less pumping pressure.

4.5 Inspection of Presses To maintain the quality of presses, its inspection is very strictly performed. The common test performed is Dye penetrant inspection (DPI). Skilled high level supervisors are employed to maintain the quality of the product,

Dye Penetrant Inspection Dye penetrant inspection (DPI), also called liquid penetrant inspection (LPI) or penetrant testing (PT), is a widely applied and low-cost inspection method used to locate surface-breaking defects in all non-porous materials (metals, plastics, or ceramics). The penetrant may be applied to all non-ferrous materials and ferrous materials; although for ferrous components magnetic-particle inspection is often used instead for its subsurface detection capability. LPI is used to detect casting, forging and welding surface defects such as hairline cracks, surface porosity, leaks in new products, and fatigue cracks on in-service components. 4.5.1 Principles DPI is based upon capillary action, where surface tension fluid low penetrates into clean and dry surface-breaking discontinuities. Penetrant may be applied to the test component by dipping, spraying, or brushing. After adequate penetration time has been allowed, the excess penetrant is removed, a developer is applied. The developer helps to draw penetrant out of the flaw where an invisible indication becomes visible to the inspector. Inspection is performed under ultraviolet or white light, depending upon the type of dye used - fluorescent or non-fluorescent (visible).

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Fig.4.2 1. Section of material with a surface-breaking crack that is not visible to the naked eye. 2. Penetrant is applied to the surface. 3. Excess penetrant is removed. 4. Developer is applied, rendering the crack visible.

4.5.2 Inspection steps 1. Pre-cleaning The test surface is cleaned to remove any dirt, paint, oil, grease or any loose scale that could either keep penetrant out of a defect, or cause irrelevant or false indications. Cleaning methods may include solvents, alkaline cleaning steps, vapor degreasing, or media blasting. The end goal of this step is a clean surface where any defects present are open to the surface, dry, and free of contamination.

2. Application of Penetrant The penetrant is then applied to the surface of the item being tested. The penetrant is allowed dwell time to soak into any flaws (generally 5 to 30 minutes). The dwell time mainly depends upon the penetrant being used, material being testing and the size of flaws sought. As expected, smaller flaws require a longer penetration time. Due to their incompatible nature one must be careful not to apply solvent-based penetrant to a surface which is to be inspected with a water-washable penetrant.

3. Excess Penetrant Removal The excess penetrant is then removed from the surface. The removal method is controlled by the type of penetrant used. Water-washable, solvent-removable, lipophilic post-emulsifiable, or hydrophilic postemulsifiable are the common choices. Emulsifiers represent the highest sensitivity level, and chemically interact with the oily penetrant to make it removable with a water spray. When using solvent remover and lint-free cloth it is important to not spray the solvent on the test surface directly, because this can remove the penetrant from the flaws. If excess penetrant is not properly removed, once the developer is applied, it may leave a background in the developed area that can mask indications or defects. In addition, this may also produce false indications severely hindering your ability to do a proper inspection.

4. Application of Developer After excess penetrant has been removed a white developer is applied to the sample. Several developer 26

types are available, including: non-aqueous wet developer, dry powder, water suspendable, and water soluble. Choice of developer is governed by penetrant compatibility (one can't use water-soluble or suspendable developer with water-washable penetrant), and by inspection conditions. When using nonaqueous wet developer or dry powder, the sample must be dried prior to application, while soluble and suspendable developers are applied with the part still wet from the previous step. Developer should form a semi-transparent, even coating on the surface. The developer draws penetrant from defects out onto the surface to form a visible indication, commonly known as bleed-out. Any areas that bleed-out can indicate the location, orientation and possible types of defects on the surface. Interpreting the results and characterizing defects from the indications found may require some training and/or experience, the indication size is not the actual size of the defect.

5. Inspection The inspector will use visible light with adequate intensity (100 foot-candles) for visible dye penetrant. Ultraviolet (UV-A) radiation of adequate intensity (1,000 micro-watts/cm2 is common), along with low ambient light levels (less than 2 foot-candles) for fluorescent penetrant examinations. Inspection of the test surface should take place after a 10 minute development time. This time delay allows the blotting action to occur. The inspector may observe the sample for indication formation when using visible dye. It is also good practice to observe indications as they form because the characteristics of the bleed out are a significant part of interpretation characterization of flaws.

6. Post Cleaning The test surface is often cleaned after inspection and recording of defects, especially if post-inspection coating processes are scheduled.

4.5.3 Advantages and Disadvantages • The main advantages of DPI are the speed of the test and the low cost. • The main disadvantages are that it only detects surface flaws and it does not work on very rough surfaces. Also, on certain surfaces a great enough color contrast cannot be achieved or the dye will stain the work piece 4.5.4 Standards for DPI International Organization for Standardization (ISO) • ISO 3059, Non-destructive testing - Penetrant testing and magnetic particle testing Viewing conditions • ISO 3452-1, Non-destructive testing. Penetrant testing. Part 1. General principles • ISO 3452-2, Non-destructive testing - Penetrant testing - Part 2: Testing of penetrant materials 27

• ISO 3452-3, Non-destructive testing - Penetrant testing - Part 3: Reference test blocks • ISO 3452-4, Non-destructive testing - Penetrant testing - Part 4: Equipment • ISO 3452-5, Non-destructive testing - Penetrant testing - Part 5: Penetrant testing at temperatures higher than 50 °C • ISO 3452-6, Non-destructive testing - Penetrant testing - Part 6: Penetrant testing at temperatures lower than 10 °C • ISO 12706, Non-destructive testing - Penetrant testing – Vocabulary • ISO 23277, Non-destructive testing of welds - Penetrant testing of welds - Acceptance levels American Society of Mechanical Engineers (ASME) • ASME Boiler and Pressure Vessel Code, Section V, Art. 6, Liquid Penetrant Examination • ASME Boiler and Pressure Vessel Code, Section V, Art. 24 Standard Test Method for Liquid Penetrant Examination SE-165 (identical with ASTM E-165)

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