|
Deep Rolling
Deep rolling is a method of cold work deformation and burnishing of internal combustion engine crankshaft journal fillets to increase durability and design safety factors. Compressive residual stress In materials science and solid mechanics, residual stresses are stresses that remain in a solid material after the original cause of the stresses has been removed. Residual stress may be desirable or undesirable. For example, laser peening i ...es can be measured below the surface of a deep-rolled fillet. Other types of fillets on shafts or tubes can also benefit from this method. Cast iron crankshafts will experience the most improvement potentially doubling their fatigue life. Typically the crankshaft is machined with under-cut fillets as opposed to tangential radiused for ease of manufacture, although all types can be deep-rolled. Most automakers are currently utilizing this crankshaft technology including: General Motors LLC, Ford Motor Company, and Fiat Chrysler Automobil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cold Work
Cold is the presence of low temperature, especially in the atmosphere. In common usage, cold is often a subjective perception. A lower bound to temperature is absolute zero, defined as 0.00K on the Kelvin scale, an absolute thermodynamic temperature scale. This corresponds to on the Celsius scale, on the Fahrenheit scale, and on the Rankine scale. Since temperature relates to the thermal energy held by an object or a sample of matter, which is the kinetic energy of the random motion of the particle constituents of matter, an object will have less thermal energy when it is colder and more when it is hotter. If it were possible to cool a system to absolute zero, all motion of the particles in a sample of matter would cease and they would be at complete rest in the classical sense. The object could be described as having zero thermal energy. Microscopically in the description of quantum mechanics, however, matter still has zero-point energy even at absolute zero, because ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Internal Combustion Engine
An internal combustion engine (ICE or IC engine) is a heat engine in which the combustion of a fuel occurs with an oxidizer (usually air) in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal combustion engine, the expansion of the high-temperature and high- pressure gases produced by combustion applies direct force to some component of the engine. The force is typically applied to pistons ( piston engine), turbine blades (gas turbine), a rotor (Wankel engine), or a nozzle ( jet engine). This force moves the component over a distance, transforming chemical energy into kinetic energy which is used to propel, move or power whatever the engine is attached to. This replaced the external combustion engine for applications where the weight or size of an engine was more important. The first commercially successful internal combustion engine was created by Étienne Lenoir around 1860, and the first modern internal combustion engi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crankshaft
A crankshaft is a mechanical component used in a piston engine to convert the reciprocating motion into rotational motion. The crankshaft is a rotating shaft containing one or more crankpins, that are driven by the pistons via the connecting rods. The crankpins are also called ''rod bearing journals'', and they rotate within the "big end" of the connecting rods. Most modern crankshafts are located in the engine block. They are made from steel or cast iron, using either a forging, casting or machining process. Design The crankshaft located within the engine block, held in place via main bearings which allow the crankshaft to rotate within the block. The up-down motion of each piston is transferred to the crankshaft via connecting rods. A flywheel is often attached to one end of the crankshaft, in order to smoothen the power delivery and reduce vibration. A crankshaft is subjected to enormous stresses, in some cases more than per cylinder. Crankshafts for sing ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Journal (mechanics)
A plain bearing, or more commonly sliding contact bearing and slide bearing (in railroading sometimes called a solid bearing, journal bearing, or friction bearing), is the simplest type of bearing, comprising just a bearing surface and no rolling elements. Therefore, the journal (i.e., the part of the shaft in contact with the bearing) slides over the bearing surface. The simplest example of a plain bearing is a shaft rotating in a hole. A simple linear bearing can be a pair of flat surfaces designed to allow motion; e.g., a drawer and the slides it rests on or the ways on the bed of a lathe. Plain bearings, in general, are the least expensive type of bearing. They are also compact and lightweight, and they have a high load-carrying capacity. Design The design of a plain bearing depends on the type of motion the bearing must provide. The three types of motions possible are: * ''Journal'' (''friction'', ''radial'' or ''rotary'') ''bearing'': This is the most common type of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fillet (mechanics)
In mechanical engineering, a fillet is a rounding of an interior or exterior corner of a part design. An interior or exterior corner, with an angle or type of bevel, is called a "chamfer". Fillet geometry, when on an interior corner is a line of concave function, whereas a fillet on an exterior corner is a line of convex function (in these cases, fillets are typically referred to as rounds). Fillets commonly appear on welded, soldered, or brazed joints. Applications * Stress concentration is a problem of load-bearing mechanical parts which is reduced by employing fillets on points and lines of expected high stress. The fillets distribute the stress over a broader area and effectively make the parts more durable and capable of bearing larger loads. * For considerations in aerodynamics, fillets are employed to reduce interference drag where aircraft components such as wings, struts, and other surfaces meet one another. * For manufacturing, concave corners are sometimes filleted t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Safety Factor
In engineering, a factor of safety (FoS), also known as (and used interchangeably with) safety factor (SF), expresses how much stronger a system is than it needs to be for an intended load. Safety factors are often calculated using detailed analysis because comprehensive testing is impractical on many projects, such as bridges and buildings, but the structure's ability to carry a load must be determined to a reasonable accuracy. Many systems are intentionally built much stronger than needed for normal usage to allow for emergency situations, unexpected loads, misuse, or degradation (reliability). Definition There are two definitions for the factor of safety (FoS): * The ratio of a structure's absolute strength (structural capability) to actual applied load; this is a measure of the reliability of a particular design. This is a calculated value, and is sometimes referred to, for the sake of clarity, as a ''realized factor of safety''. * A constant required value, imposed by law, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Residual Stress
In materials science and solid mechanics, residual stresses are stresses that remain in a solid material after the original cause of the stresses has been removed. Residual stress may be desirable or undesirable. For example, laser peening imparts deep beneficial compressive residual stresses into metal components such as turbine engine fan blades, and it is used in toughened glass to allow for large, thin, crack- and scratch-resistant glass displays on smartphones. However, unintended residual stress in a designed structure may cause it to fail prematurely. Residual stresses can result from a variety of mechanisms including inelastic (plastic) deformations, temperature gradients (during thermal cycle) or structural changes ( phase transformation). Heat from welding may cause localized expansion, which is taken up during welding by either the molten metal or the placement of parts being welded. When the finished weldment cools, some areas cool and contract more than othe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Undercut (manufacturing)
In manufacturing, an undercut is a special type of recessed surface that is inaccessible using a straight tool. In turning, it refers to a recess in a diameter generally on the inside diameter of the part. In milling, it refers to a feature which is not visible when the part is viewed from the spindle. In molding, it refers to a feature that cannot be molded using only a single pull mold. In printed circuit board construction, it refers to the portion of the copper that is etched away under the photoresist. Turning On turned parts an undercut is also known as a ''neck'' or "relief groove". They are often used at the end of the threaded portion of a shaft or screw to provide clearance for the cutting tool. Molding Undercut - Any indentation or protrusion in a shape that will prevent its withdrawal from a one-piece mold. Milling In milling the spindle is where a cutting tool is mounted. In some situations material must be cut from a direction where the feature can not be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Roller Burnish
Roller burnishing is a surface finishing technique where hardened rollers cold work surface imperfections to reduce surface roughness. Roller burnishing differs from abrasive surface finishing techniques in that material is displaced rather than removed. The tooling typically consists of a hardened sphere or cylindrical roller. The tooling is pressed into the surface of the part while it is rotated (in some applications, the tools are rotated instead of the part). The burnishing tool rolls against the surface of the part at a constant speed, producing a very consistent finish across the part. A surface finish of less than Ra 0.1 µm is achievable with roller burnishing. A side effect is that the outer surface of the part is work hardened. Roller burnishing is used in the production of some crankshafts. A dual roller (cylindrical) tool is moved into the thrust bearing journal of a crankshaft, while the crankshaft is spinning the tool is indexed (so each roller is perpendicul ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metal Forming
Forming, metal forming, is the metalworking process of fashioning metal parts and objects through mechanical deformation; the workpiece is reshaped without adding or removing material, and its mass remains unchanged. Forming operates on the materials science principle of plastic deformation, where the physical shape of a material is permanently deformed. Characteristics Metal forming tends to have more uniform characteristics across its subprocesses than its contemporary processes, cutting and joining. On the industrial scale, forming is characterized by: * Very high loads and stresses required, between 50 and () * Large, heavy, and expensive machinery in order to accommodate such high stresses and loads * Production runs with many parts, to maximize the economy of production and compensate for the expense of the machine tools Forming processes Forming processes tend to be categorised by differences in effective stresses. These categories and descriptions are highly simplif ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
