Industrial Training Report ( Engine Valves )
Embed Size (px)
Transcript of Industrial Training Report ( Engine Valves )
CHAPTER 1 Introduction
1.1 About the Company REVL Ltd, Chennai.
Fig 1 Company logo
RANE was founded in 1929 as Rane Private Ltd., trading in Automobiles Parts. In 1959 ENGINE VALVES LTD was established for manufacturing Internal Combustion engine valves. Rane EVL is a part of 300 crores Rane group of companies. The company commenced manufacturing of valves on 1959 in collaboration with Farnborough Engineering Company, UK (1959-1973). In 1982 REVL, commenced first medical plant in Hyderabad. In 1989 REVL commenced shop 3 at Chennai plant. In 1993 REVL created its own R&D facility in Chennai. The main product range of Rane Engine Valves are valves, valves guides, Camshafts, Tappets. REVL is the leading manufacturer of Engine Valves and Valve Train components in India. Valves are being exported throughout the globe. The ISO 9001 certificated from RWTUV, Germany shows the effective quality system being practiced. Here REVL have average monthly sales of 11 lacs in three market sectors. In this 7 lacs goes to OE sector, 2 lacs each goes to both replacement sector and export sector. The average production per day is 53000. Foreign exchange earned during 2002-2003 is Rs. 293.71 million. As at the end of March 2003, the total number of employees stands at 1462. RANE plant 1 is located in Chennai its main product is engine valves, the annual capacity is about 9 Million and total area in Sq.mts is about 56500. Build up area is about 18860. REVL total market share in India is about 60 %. In 1998 the name of the company has been changed to Rane engine valves after the merger of ECL.
Today REVL is the largest manufacturer of valves in India, the fourth largest in asia and seventh largest in the world. Since inception in 1959 to data, the company has been a market leader in India. Major Domestic Customers: LML Bajaj Auto Limited Cummins India Eicher Motors Enfield India Escorts Hyundai Motors Fiat India Hero Honda Motors Hindustan Power Plus L & T John Deere Hindustan Motor Tata Cummins Ashok Leyland Mahindra & Mahindra Maruti Udyog (Suzuki) TVS Motors Swaraj Mazda Yamaha Motors Major overseas customers: Deutz, Germany Case New Holland, Uk Lister Petter, UK Perkins, UK Elgin World Trade, US Msi Motors, Germany Nason, Australia Precision Parts, US2
1.2 What is an Engine valve ? Valves are used to control gas flow to and from cylinders in automotive internal combustion engines. The most common type of valve used is the poppet valve .The valve itself consists of a disc-shaped head having a stem extending from its center at one side. The edge of the head on the side nearest the stem is accurately ground at an angle usually 45 degrees, but sometimes 30 degrees, to form the seating face. When the valve is closed, the face is pressed in contact with a similarly ground seat.
Fig1.2 Valve Nomenclature The two main types of internal combustion engine are: spark ignition (SI) engines (petrol, gasoline, or gas engines), where the fuel ignition is caused by a spark; and compression ignition (CI) engines (diesel engines), where the rise in pressure and temperature is high enough to ignite the fuel. Valves are used in these engines to control the induction and exhaust processes.
Both types of engine can be designed to operate in either two strokes of the piston or four strokes of the piston. The four-stroke operating cycle can be explained by reference to Fig. 1.3. This details the position of the piston and valves during each of the four strokes. The induction stroke: The inlet valve is open. The piston moves down the cylinderdrawing in a charge of air. The compression stroke: Inlet and exhaust valves are closed. The piston moves up the cylinder. As the piston approaches the top of the cylinder (top dead centre tdc) ignition occurs. In engines utilizing direct injection (DI) the fuel is injected towards the end of the stroke. The expansion stroke: Combustion occurs causing a pressure and temperature rise Which pushes the piston down. At the end of the stroke the exhaust valve opens. The exhaust stroke: The exhaust valve is still open. The piston moves up forcing exhaust gases out of the cylinder.
Fig 1.3 The Four stroke Process
1.3 Operating Conditions During each combustion event, high stresses are imposed on the combustion chamber side of the valve head. These generate cyclic stresses peaking above 200 MN/m2 on the port side of the valve head. The magnitude of the stresses is a function of peak combustion pressure. The stresses are much higher in a compression ignition engine than a spark ignition engine. A typical inlet valve temperature distribution is shown in Fig. 1.4. It was not made clear whether these were experimental or theoretical values or whether the valve was from a diesel or gasoline engine. The asymmetric distribution may have been due to non-uniform cooling or deposit build-up affecting heat transfer from the valve head. As shown in Fig. 1.5., exhaust valve temperatures are much higher. Although both inlet and exhaust valves receive heat from combustion, the inlet valve is cooled by incoming air, whereas the exhaust valve experiences a rapid rise in temperature in the valve head, seat insert, and underhead area from hot exhaust gases.
Fig 1.4 Inlet valve temperature distribution Fig 1.5 Exhaust Valve Distribution
1.4 Material of the valve New valve materials and production techniques are constantly being developed, these advances have been outpaced by demands for increased engine performance. These demands include: Higher horsepower-to-weight ratio; Lower specific fuel consumption; Environmental considerations such as emissions reduction; Extended durability (increased time between servicing).
The criteria for engine valve material: Resistance to high-temperature corrosion [ ~700C ] Hot strength (endurance strength at high temperature ) [ ~500MPa ] Hot hardness [ strength at ~700C ] Resistance to oxidation Resistance to seizing and adhesive wear Availability of material supplied Overall cost (material and manufacturing costs)
Most inlet valves are manufactured from a hardened, martensitic, low-alloy steel. These provide good strength and wear and oxidation resistance at higher temperatures. Exhaust valves are subjected to high temperatures, thermal stresses, and corrosive gases. Most exhaust valves are manufactured from austenitic stainless steels. These can be iron, or nickel, based. Solid solution and precipitation strengthening provide the hot hardness and creep resistance required for typical exhaust valve applications. The 21.4N composition is widely used in diesel engine exhaust valve applications. This alloy has an excellent balance of hot strength, corrosion resistance, creep resistance, fatigue resistance, and wear properties at an acceptable cost . In heavy-duty diesel engine applications higher strengths and creep resistances are attained by using superalloys as valve materials. Valve seating face wear and corrosion can be reduced by applying seat facing materials. Stellite facings are commonly used for passenger car applications.
CHAPTER 2 Manufacturing2.1 Production Sequence Manufacturing of engine valves involve many complex processes that require a very high level of precision. There many valve configurations depending on the specifications given by the customer. Thus there are many different production lines operating simultaneously to cater to the demand. Each line has a unique production sequence, however some of the basic manufacturing processes being the same for most of them. Following is the production sequence of a typical Deutz inlet valve . Bar Storage : The alloy steel bars are received from the suppliers and stored in the stores. The parent material of the valve is martensitic EN-52 material. The EN-52 material is colourcoded in oxford blue. The bars are usually supplied in the form of very long rods (about 4200mm), which are then cut to an approximate length before forging.
Bar cut-off: The rods are cut to an approximate length of about 263mm before upsetting. Allowances are given before cut-off to provide machining allowances.
Bar Grinding: After the bars are cut, the ends of the bar are made to undergo face grinding to ensure flat surfaces at both faces of the bar. These flat surfaces play a vital role during upsetting in spreading the heat uniformly along the length of the bar. After grinding the ends of the bar, the edges are chamfered in a rough manner.
Fricion Welding: Friction welding is a process of joining head part of the engine valve with the straight rod use lathe machine. Friction welding technology is a completely mechanical solid-phase process in which heat generated by friction is used to create high-integrity joint between similar or dissimilar metals, and even thermoplastics.
In engine valve production, this process is used to join valve head to the valve stem. This process is especially applicable for exhaust valves since the head of the valve has to withstand much higher temperatures and pressures than its inlet counterpart . The Friction welding ensures that a seamless joint is formed between the head and the stem. It is done by bringing in contact the head and the valve material rods rotating at a minimum speed of 2000rpm. Due to the high speeds tremendous amount of heat is generated and the material at the junction melts giving way for the weld.
Fig 2.1 Friction welding between two rotating components In Friction Welding the quality control cost is minimal with a guarantee for high quality welds and the weld cycle is also very short Upsetting: The bars then undergo the electric upsetting process wherein the bars are placed in an upsetting M/C and electrical resistance is made to pass through o