Manufacturing Processes Report(发动机制造工艺)

Manufacturing ProcessesContents:Introduction 2 Engine block 2-4 Crank Shaft 5-9 Connecting rod 10-14 Conclusion 15 Appendices 16Introduction:There are thirteen parts in the engine as shown in above figure, I will discuss three parts of the engine. Engine block, Crankshaft and Connecting rod.In the following section, I will discuss the function, material used, mechanical properties of the part, the quality requirements and the process used of producing those parts.Engine block:1-1 Description:The Engine Block is a single unit that contains all the pieces for the engine. The block serves as the structural framework of the engine and carries the mounting pad by which the engine is supported in the chassis . The block is made of cast iron and sometimes aluminum for higher performance vehicles. The engine block is manufacturedto withstand large amounts of stress and high temperatures.1-2. Production requirements:The Internal design of the engine block must be extremely precise, because all parts must fit and be able to function properly once the entire engine is assembled. The outside design of the engine only has to fit fewer requirements like attaching to the car properly. Engines are made in all different shapes and sizes to fit inside the frame of the car, therefore a company must be able to manufacture many different engine block designs yet keep up with product demand. There are 6000-8000 engine blocks made a day at a highly qualified company, this may be for many different models.1-3. Process Requirements:The Engine block goes through two manufacturing processes before it is ready for assembly. The first process is die casting manufacturedusing cast iron. The strength of the piece depends on the type of iron used and if any other materials are added. The higher strength iron alloys can include Molybdenum, Chrome or Copper for increased strength.For the engine block the hot-chamber process is used. This process uses a die cut into three parts then combined using a large amount of pressure and temperature. Two parts of the die will contain extrusions to produce holes and cavities. This eliminates much machine process and saves time. Then all the die parts are forced together with the material inside to produce the engine block cast. Once the part has been casted then cooled (using a chill plat) the second process may be preformed. This processes is machining and is very important the overall performance of the engine.The first machining process is to bore out the cylinders for the pistons and then for the camshaft. Next the cylinders need to be sleeved; this provides the surface with a small gradient to trap an oil film. The next operation is to grind down and area for the bearing to set in, this does not have to be surface finished because bushings will be set down in first. The next operation is end milling. This will provide a smooth surface finish for the joining of the oil pan, the crankshaft cap and areas for mounting. The final operations include drilling, reaming and taping. These provide locations for the engine block to be mounted.Crankshaft:2-1. Descriptions:All the pistons in the engine are connected through individual connecting rods to a common crankshaft. The crankshaft is located below the cylinders on an in-line engine,at the base of the V on a V-type engine and between the cylinder banks on a flat engine. As the pistons move up and down, they turn the crankshaft just like our legs pump up and down to turn the crank that is connected to the pedals of a bicycle.The materials used in producing crankshaft including cast iron and steel. It depends on manufacturer and the strength needed. For racing car, steel will usually be used. It is used for transform the rotation of the cylinder due to the combustion process that take place in the engine.2-2. Product requirement:The quality requirement of crankshaft is high. It need high precisions because it used to transform the rotations, it should precisely produce such that that it can transmit that rotation correctly. The production amount of crankshaft depends on the manufacturer, however, since it is a replaceable part for engine, some producer actually producing more. The production rate depends on the process used and the crankshaft usually can be produce using two methods, such as expandable pattern casting (lost form) and forging. Here we will just discuss the forging process.2-3. Process used:The process use in the production of the crankshaft is bulk deformation process called the forging process. Crankshafts are a high cost replacement item.1. Forged and precision machined from premium, high strength steel.2. Heat treated by hardening process for high strength and outstanding wears characteristics.3. Journals are finish-ground and polished assuring ultimate smoothness for less internal friction and long bearing life.4. All crankshaft are precision balanced, both statically anddynamically to provide long life.The forging process is a process of processing work piece having a relatively small surface area-to-volume ratio. It is a process by which plastic deformation of the work piece is carried out by compressive forces. Forging is one of the oldest metalworking operations known. This process can be carrying out at room temperature or at an elevated temperature. Called the hot forging or the cold forging. This process is being chosen to produce the crankshaft is because it gives high precision and also harden the material either by hot work or cold work.The production of the crankshaft involves several different stages so to get the desired shape. These steps are describe in the following diagram:Figure 2. Intermediate stages in forging a crankshaftThese steps is needed because the proper design of the forging dies and selection of die materials required considerable experience and knowledge of the strength and ductility of the workpiece material, its sensitivity to strain rate and temperature, and its frictional characteristics. From Figure 2, we can see that there are five passes in the forging process of a crankshaft. These intermediate stages are important for distributing the material and filling the die cavities properly.The materials use in the production of crankshaft depends on its application. For best performance, the crankshaft is made by steel using the forging process. For some application, the crankshaft can be produce by casting process and the material used can be cast iron. For crankshaft produced using casting process, the following requirement must be made:1. Upgraded Nodular cast iron 80-60-06 to be selected for material which metal microstructure consists of pearlite iron 80 to 90%, graphite type over grade 2 and size over grade 3.2. All casting pieces are instruments checked for pearlite and graphite. The deflection of straightness of casting piece should not be over 5/1000". Ultrasonic inspection for internal defect is an essential process for every casting piece to eliminate any internal defective.3. All journals' radius is enlarged to eliminate stress spots and surface micro polished to 0.25 um. The roundness & size of every journal designed to be accurate to .0001". Magnaflux inspection on all journal surfaces upon completion of machining to ensure perfection.The material use in the crankshaft is AISI 5140 steel is a medium carbon with chromium. Chromium has a twin effect on steel, acting as a carbide former. This improves the harden ability, allowing deeper hardening with less quenching medium.Chromium also improves the corrosion resistance better than plain carbon steel. Currently, to produce a very good quality crankshaft, the manufacturing process of every crankshaft involves 9 basic operations: Magnafluxing, larger journal radius, main side grinding, flywheel flange grinding, oil holes chamfering, journal micro-finishing, and ultrasonic testing. Also, All journals are induction hardened to HRC 55 and above for high performance applications.Connecting rod and rod cap:3-1 Description:Connecting Rods are forged for high strength and toughness. They are hardened and machined to close tolerances to ensure straightness, correct weight and alignment.The connecting rod purpose is to link the piston and crank shaft together. Thus the work done by the piston is transferred to the crank shaft, minus the frictional forces acting on this subsystem. The rods are made of forged steel and have secondary machining operations on critical diameters. Due to the majority of work being doneby the piston, the connecting rod must have a strong compression strength. There are very minimal tensile forces acting on the rod, and they only last for a fraction of a second. The forged steel rods have been strain strengthen during their multiple step formation process.3-2. Production requirements:Rod compression strength is of the up most importance. Failure of a rod can puncture a hole in the engine block. The forging process then is ideal for production because of adding strain strengthening and allowing for high production quantities. The type of forging process most likely utilizes a hot closed die followed by secondary machining operations. There are the same amount of connecting rods in an engine as pistonsa. Forging process results in exceptionally high strength and durability.b. Hardening and machining to close tolerances ensure straightness, correct weight and alignment for smooth operation.c. Tight piston pin and crankshaft bore tolerances provide an exact fit with other components for top performance and long life.d. Endurance testing—up to four million cycles under normal loads—ensures durability.Power Engine Part's Chrome Nickel Moly Steel Racing Rods are manufactured from the highest aircraft quality Chrome Moly Steel using precision engineering techniques for Racing and High performance applications.Rods and Caps are separately forged from Aircraft Quality Chrome Moley Steel to obtain optimum grain flow. The AUTOCAD 14 blue print allows the super racing rods to fit into any stroke. All big and small ends are finished with SUNNEN cross grind. All cap screws are specially designed and manufactured for C.A.T. by ARP for stroker application.1. A18 aluminum bronze wrist pin bushings are made to withstand higher impact force. A third hole drilled at end of the bushing releases any air pockets from the bushing.2. Rods and caps are forged separately from the highest quality steel to obtain optimum grain flow.3. Surface hardness HRB 228-269 to ensure higher tensile strength.4. All rods have been treated with magnaflux inspection, stress relieve, and shot peening.5. Weight control for each rod within five(5) gram tolerance, and balanced for every set within eight(8) grams tolerance.6. ARP bolts with tensile strength over 190,000 PSI.7. Center to Center precision manufacturing with tolerances within 0.001" to obtain the best possible performance.3-3. Process Description:The process used in manufacturing the connecting rod and caps are forging as we have discussed before in the process of manufacturing the crankshaft. Starting with a heated rod blank an initial form is given to the rod. After two to three more dies the final shape of the rod is completed. However the flashing must be trimmed by yet another die which shears off the rough edge and produces two holes in either end of the rod. One large hole for connection to the crank shaft and a second smaller hole for connection to the piston pin. The process of this forging process are shown in Figure 3.Figure 3. Forging process for producing a connecting rod.The final operations are done using machining procedures. First the large and small holes are milled by a tool in a similar fashion to drilling but more precise. Then the two raised edges surrounding the holes are milled flat and are perpendicular to the length of the hole. Most likely a milling and drilling operation are happening at the same time for the connecting rod bolts which are used to hold the next operation pieces together. In order for assembly the larger of the two holes is cut in half. The cut is made perpendicular to the length of the rod and must have a good surface finish so as not having to need any more machining. Finally the small and large holes are ground leaving a very smooth surface finish. However grinding the ID of large hole is some what more complicated because there are two pieces. Using automation the two pieces are held together while grinding takes place.Not mentioned in description of the rod is that when forming the part, the larger hole must be elliptical. When the cutting of the large hole occurs some material is removed and this needs to be compensated for. The amount of the larger diameter minus the minor diameter is roughly the amount of material that can be allowed for cutting the larger hole in half.Conclusion:Many process are used to produce parts and shapes. There is usually more than one method of manufacturing a part from a given material. The manufacturing process to produce a particular part involves many considerations. Some of these considerations include cost, appearance, volume of production, application of the material, and many other issues. In this report, I try my best to find out the best method to produce the parts in a engine. Also, we need to know that manufacturing process of parts keep changing because new technology showing up. And a good method to produce one part today may not be a good method tomorrow since technology keeps improving.Manufacturing is a process of converting raw material into produce that is useful. A key task for manufacturing engineering is to select an optimal manufacturing method among multiple alternatives, given product design goals, process capabilities, and cost considerations. Beside this, the selection of materials for different parts is also important in determining a best manufacturing process.In writing this report, I have learned the various possible process to produce a part. It all depends on the manufacturer and also the material used.Appendices://Products.htm/facts/wwhy2.htm/harmonic_balancers.htm /case_studies/allen.htm /faq/introduction/whatis.htm /catalog1382.html/vprocess.htm/metalcastprocess.htm/forging.html。