International Journal of Research in Advent Technology, Vol.2, No.6, June 2014 E-ISSN: 2321-9637
Design and Fabrication of a Fixture for Differential Carriers R149.5 and R149.7 Chetan Appasab Chougale1, Kiran K2, Rajgopal3, Anantharaja M H4 PG Scholar, Department of Machine Design, Dept. of PG Studies, VTU Gulbarga-585 1051 PG Scholar, Department of Thermal Power Engineering, Dept. of PG Studies, VTU Gulbarga-585 1052,3,4 Visvesvaraya Technological University, Belgaum, Karnataka-590 018. chetanchougule.a10@gmail.com1, kirankavalli@gmail.com2, rajgopal7@yahoo.com3, anantharajamh@gmail.com4 Abstract: At present scineario productivity and economics of machining work pieces in a large quantity is greatly affected with the use of work holding devices like fixtures. This device reduce the production cost and ensure interchangeability of machined work pieces. In the present study R149.5 and R149.7 are the different kinds of differential carriers of ASHOK LEYLAND used. A differential carrier is a casing or cage which carries differential gears. These differential gear arrangement permits transmission of power from the engine to a pair of driving wheels and distributes the force equally between them but permitting them to follow different path lengths during turning a corner or traversing an uneven road. But on straight road the wheels rotate at the same speed. To achieve required accuracy with reduced rework and easy handling fixtures are provided. Our research methodology aims at optimal design and fabrication of fixture. The fixture is designed and fabricated mainly to get the dimension of workpieces within tolerance limit. Index Terms: Fixture, Differential carrier, Ashok Leyland, R149.5, R149.7. 1. INTRODUCTION 1.1. Differential Carriers A differential is a particular type of simple planetary gear train that has the property that the angular velocity of its carrier is the average of the angular velocities of its sun and annular gears. The differential carrier principle can be accomplished by packaging the gear train so it has a fixed carrier train ratio R = -1, which means the gears corresponding to the sun and annular gears are the same size, which can be done by engaging the planet gears of two identical and coaxial epicyclic gear trains to form a spur gear differential. A similar approach is to use bevel gear differential consisting of bevel gears for the sun and annular gears and a bevel gear as the planet.[1] A differential couples the drive shaft to half-shafts that connect to the rear driving wheels of automobiles and other wheeled vehicles. During turning the differential gear enables the outer drive wheel to rotate faster than the inner drive wheel. This is most essential during the vehicle turning, which makes the outer wheel of the turning curve roll farther and faster than the other. The average of the rotational speed of the two driving wheel equals the input rotational speed of the drive shaft. Which is accomplished by increasing in the speed of one wheel is balanced by a decreasing in the speed of the other.[1]
Fig. 1. A spur gear differential constructed by engaging the planet gears of two co-axial epicyclic gear trains. The casing is the carrier for this planetary gear train.
Fig.2. 1. Adjusting Nut Lock (aka Adjusting Nut Retainer) 2. Adjusting Nut 3. Carrier (in this case, a mighty 14-bolt ARB Air Locker) A differential consists of one input drive shaft with two drive wheels as output. However the rotation of
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International Journal of Research in Advent Technology, Vol.2, No.6, June 2014 E-ISSN: 2321-9637 the drive wheels are coupled by their connection to the roadway. During normal conditions the ratio of the speeds of the two driving wheels is defined by the ratio of the radii of the paths around which the two wheels are rolling with small tyre slip. This is determined by the track-width of the vehicle and the radius of the turn.[2] 1.2. Fixture Fixtures may be defined as devices used in manufacture of duplicate parts of machines and intended to make possible inter changeable work at a reduced cost, as compared with the cost of reducing each machine detail individually. Fixtures serve the purpose of holding and properly locating a piece of work, while it is machined & are provided with necessary appliances for guiding supporting, setting, gauging the tool in such a manner that all the work produced in same fixture will be alike in all respects even with the employment of unskilled labour.[3] The first factory-made product were created one at a time. Early artisans started with very little quite raw materials and a rough plan of the finished product. They made every product piece by piece, creating every half singly and fitting the components into the finished product. This method took time. Moreover, the standard and consistency of product varied from one artificer to succeeding. As they worked, early producing pioneers completed the necessity for higher strategies and developed new ideas. Eventually, they found the key of mass production: standardized components. commonplace components not solely speeded production, they conjointly ensured the changeability of components. the concept could also be obvious nowadays, however in its time, it had been revolutionary. These commonplace components were the key to facultative less-skilled employees to copy the talent of the craftsman on a repetitive basis. the first technique of achieving consistent half configuration was the example. Templates for layout, sawing, and filing allowable every employee to form components to a customary style. whereas early templates were crude, they a minimum of gave virtuoso employees a customary kind to follow for the half. Building on the example plan, employees made alternative guides and work holders to form their jobs easier and also the results a lot of certain. These guides and work holders were the ancestors of today's jigs and fixtures.
Yesterday's work holders had identical 2 basic functions as today's: firmly holding and accurately locating a piece of work. Early jigs and fixtures might have lacked trendy refinements, however they followed several of identical principles as today’s work holder styles. A fixture's primary purpose is to create a secure mounting point for a workpiece. Which in turn acts as a support during operation and increased accuracy, reliability, interchangeability and precision in the finished parts. This also serves to reduce working time by allowing quick set-up and by smoothing the transition from workpiece to workpiece.[4] It frequently reduces the complexity of a process, which allows for unskilled workers to perform it and effectively transferring the skill of the tool maker to the unskilled worker.[3] These Fixtures also allow for a higher degree of operator safety by reducing the concentration and effort required to hold a piece steady.[4] Fixtures must always be designed with cost effectiveness in mind. The main purpose of these devices is to reduce costs, so that it can be designed in such a way that the cost reduction outweighs the cost of implementing the fixture. This is usually much better, from an economic standpoint for a fixture to result in a small cost reduction for a process in constant use, compared for a large cost reduction for a process used only occasionally.[5] In practice a common bench vise has left jaw which is the immovable and the right jaw is the movable clamp. Most fixtures have a solid component which is affixed to the floor or to the body of the machine and considered immovable relative to the motion of the machining bit with one or more movable components known as clamps. The clamps allow workpieces to be easily placed in the machine or removed which secures safe during operation. Some of it kinds are also adjustable, which allows handling for workpieces of different sizes to be used for different operations. The Fixtures must be designed such that the pressure or motion of the machining operation is directed primarily against the solid component of the fixture. By taking above Precautions it enhances the likelihood that the fixture will fail due to interrupting the operation and potentially causing damage to components, infrastructure, operators.[6]
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International Journal of Research in Advent Technology, Vol.2, No.6, June 2014 E-ISSN: 2321-9637 1.3. 3.1 Types OF fixtures The names used to describe the various types of fixtures are determined mainly by how the tool is built. Jigs and fixtures are made basically the same way as far as locators and positioners are concerned. The main construction difference is mass. Because of the increased tool forces, fixtures are built stronger.
Plate fixtures
angle-plate fixture
Vise-jaw fixtures
Indexing fixtures
Multistation fixtures
Profiling fixtures
1.4. Advantages of Fixtures It reduces or sometimes eliminates the efforts of marking, measuring and setting of workpiece on a machine and maintains the accuracy of performance. The workpiece and tool are relatively located at their exact positions before the operation automatically within negligible time. So it reduces product cycle time. Variability of dimension in mass production is very low so manufacturing processes supported by use of jigs and fixtures maintain a consistent quality. Due to low variability in dimension assembly operation becomes easy, low rejection due to les defective production is observed. It reduces the production cycle time so increases production capacity. Simultaneously working by more than one tool on the same workpiece is possible. The operating conditions like speed, feed rate and depth of cut can be set to higher values due to rigidity of clamping of workpiece by jigs and fixtures. Operators working becomes comfortable as his efforts in setting the workpiece can be eliminated. Semi-skilled operators can be assigned the work so it saves the cost of manpower also. 2. LITERATURE REVIEW J. C. Trappey and C. R. Liu School of business Engineering, Purdue University, West Lafayette, IN 47907, USA (1990) [7], instructed as follows.
Fixture style are often classified as a part of method coming up with. Fixture style analysis considers problems such as: Fixture configuration - deciding the categories of fixture components needed, and choosing locating points on the elite components according to the nominal method info. Fixture assembly - constructing and assembling modular fixture components. The orientation of every element on the baseplate is set in step with the work piece set-up. Consequently, the assembly sequence of the fixture elements. Fixture verification - proving the validity of the fixture configuration considerately of some operative factors, like the cutting directions, the acting forces and therefore the machining sequence. The most rigid space is employed because the clamping position to stop cracking or bending throughout the machining method. Established fixturing techniques and methodology embrace the supporting and locating principles and therefore the clamping principles. These principles area unit thought-about in step with the pure mathematics of labor items. Virtual Reality for Fixture style and Assembly Tibeto-Burman Li, M.A (University of Nottingham, 2008) [8] declared as follows. A normal fixture style for prismatic elements consists of 3 essential elements: locators, clamps and supporters. Locators area unit used to position the work piece in static equilibrium thus on take away all degrees of freedom. Clamps area unit wont to hold the work piece firmly against the locators throughout the machining method. The primary style factors of fixture clamps comprising external cutting force and power direction etc. need to be taken into consideration throughout a fixture style method. As machining options area unit subjected to external cutting forces, the 2 fixture components need to guarantee that the work piece is stiffly settled and assure its repeatability. Repeatability refers to the work piece and therefore the resultant work piece are often exactly settled within the same position by the fixture. Fixture Feasibility: strategies and Techniques for Fixture coming up with XiumeiKang and QingjinPeng from University of Manitoba (2008) [9], He primarily talks concerning fixture coming up with. Fixture coming up with determines precise locating and rigid clamping of a piece of work in step with workpiece’s style and method needs. Locating surfaces area unit classified as plane, pin-hole and external profiles. normally used fixture locating strategies include:
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International Journal of Research in Advent Technology, Vol.2, No.6, June 2014 E-ISSN: 2321-9637 (1) 3-2-1 purpose locating for prismatic workpieces, it uses 3 locators on the first locating surface, 2 locators on the secondary locating surface, and one locater on the tertiary locating plane; (2) one plane and 2 pins locating for general elements with 2 holes. It uses a primary locating plane, a primary pin, and a secondary pin to limit the liberty of a workpiece; (3) V-block locating for external cylindrical elements. One wide V-block or 2 short V-pads is also wont to hold the piece of work. The clamping coming up with determines clamping surfaces and points on the piece of work and clamping elements, the magnitude of every clamping force, and therefore the clamping sequence once the soundness of the piece of work becomes a priority. To hold halficular part, many style constraints is also applied. Amongthem, four main constraints within the fixture coming up with area unit as follows. (1) Geometrical constraints: Correct locating of a piece of work ought to be ensured to satisfy machining accuracyrequirements of a piece of work.
The clamping forces ought to be simply spare to constrain and find the piece of work while not inflicting distortion or injury to the piece of work. ANSYS program has been used for hard the deflection of the half beneath clamping and cutting forces. 3. RESARCH METHODOLOGY: 3.1. Modelling and Design: Modeling and design were done in 2 stages: 1. 2.
2D modeling was done in AUTOCAD. 3D modeling was carried out in ELEMENTS/PRO.
CREO
(2) Accessibility constraints: There ought to be no interference among fixture elements, workpieces, and machining tools throughout assembly and machining. additionally, it ought to be straightforward to load and unload the piece of work. (3) Force constraints: The fixture ought to be robust enough to resist the forces and moments made by clampsand machining tools. A minimum clamp force ought to be nominal for the work piece stability. (4) Deformation constraints: The stiffness of a fixture system ought to be spare to stay the work piece deformation at intervals the look tolerance. Machining fixture locating and clamping position optimisation victimisation genetic algorithms Necmettin Kaya Department of engineering science, Uludag University, Gorukle, Bursa 16059, Turkey [10] A good fixture style minimizes piece of work geometric and machining accuracy errors. Another fixturing demand is that the fixture should limit deformation of the piece of work. It is necessary to think about the cutting forces aswell because the clamping forces. Finite component analysis may be a powerful tool within the resolution of a number of these issues Clamping forces area unit perpetually directed towards the locators so as to force the work piece to contact all locators.
Fig. 3. 3D assembled modelling of fixture in Pro/Engineer 3.2. Design Design criteria for fixtures To meet all design criteria for work holder is impossible, compromise is inevitable. The most important hint of optimal design objectives is positioning, holding& supporting functions that fixtures must fulfill. Position location A fixture must above all else hold the work piece, precisely in place to prevent 12 degrees of freedom, linear movement in the either direction about each axis.
Repeatability Identical work piece specimens should be located by work holder in precisely the same space on repeated loading & unloading cycles. It should be impossible to hold the work piece incorrectly.
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International Journal of Research in Advent Technology, Vol.2, No.6, June 2014 E-ISSN: 2321-9637 Adequate clamping forces The work holder must hold the work piece immobile against the forces of gravity. Centrifugal force, inertia force, wetting force, milling & the design must calculate these machines forces against the fixture holding capacity. The device must be rigid: clamping forces must be maintained. Care during loading cycles As the work holders usually receive more punishment during the loading & unloading cycle than during the machining operation. The device must endure impact & aberration for at least the life of the job. 4. ANALYSIS The software is used to analyze a board range of application. Mechanical ANSYS incorporates both structural and material non linearity’s. Fig.5. VON-Mises stress during machining
Fig. 4. Total deformation during machining Fig.6. VON-Mises elastic strain during machining
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International Journal of Research in Advent Technology, Vol.2, No.6, June 2014 E-ISSN: 2321-9637
Fig.9. VON-Mises elastic strain when work piece is on stocker plate Fig. 7. Total deformation when work piece is placed on stocker plate
5. FABRICATION PROCESS Fabrication is the use of machines, tools and labour to produce goods for use or sale. The term may refer to a range of human activity, from handicraft to high tech, but is most commonly applied to industrial production, in which raw materials are transformed into finished goods on a large scale. Such finished goods may be used for manufacturing other, more complex products. Raw material product.
Fabrication process
Finished
5.1. Fabrication of fixture Fabrication of fixture was then carried out according to design in DOOSAN HM 5000 CNC machine.
Collection of material
Fabrication of structure Fig. 8. VON-Mises stress when work piece is on stocker plate
Collection of fixture parts
Assembly of fixture
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International Journal of Research in Advent Technology, Vol.2, No.6, June 2014 E-ISSN: 2321-9637
Fig. 10. Fabricated fixture 6. RESULTS AND DISCUSSIONS The basic aim of the present study is design and fabrication of a fixture for differential carriers R149.5 & R147.7 was manufactured according to the design specifications and conditions. In order to machine the component with desired accuracy, the fixture has manufactured as shown in Fig. 10.
[4] Colvin, Fred H.; Haas, Lucian L. (1938). Jigs and Fixtures: A Reference Book. New York and London: McGraw-Hill Book Company. [5] P H Joshi, Tata McGraw-Hill Education, 2010 Jigs and fixtures. [6] Kumar, A.S., Subramaniam, V., and Teck, T.B., “Conceptual design of fixtures using machine learning techniques.” International journal of Advanced Manufacturing Technology, Vol. 16, pp. 176-181, 2000. [7] J. C. Trappey and C. R. Liu School of Industrial Engineering, Purdue University, West Lafayette, IN 47907, USA (1990). [8] Virtual Reality for Fixture Design and Assembly Qiang Li, M.A (University of Nottingham, 2008). [9] Fixture Feasibility: Methods and Techniques for Fixture Planning XiumeiKang and QingjinPeng from University of Manitoba (2008). [10] Machining fixture locating and clamping position optimization using genetic algorithms Necmettin Kaya Department of Mechanical Engineering, Uludag University, Gorukle, Bursa 16059, Turkey.
Prior to the fabrication process syudy of the loads that act on the fixture including the weieght of the body cutting forces was done. The cutting forces and weight of the component were analysed using ANSYS as shown in Fig. 4, Fig. 5, Fig. 6, Fig. 7, Fig.8 & Fig.9. The implication of design and fabrication of a fixture for differential carriers R149.5 & R147.7 have been carried out sucessfully through CNC machining and analysis results. 7. ACKNOLEDGEMENT: Authors express thier sincere thanks to “DECO EQUIPMENTS PRIVATE LIMITED”, Hebbal Industrial Estate, Metagalli, Mysore-570 016. For providing the platform to carry out this study.
REFERENCES [1] Design, Manufacturing & Analysis of Differential Crown Gear and Pinion for MFWD Axle. IOSR Journal of Mechanical and Civil Engineering (IOSR-JMCE) ISSN(e) : 2278-1684, ISSN(p) : 2320–334X, PP : 59-66. [2] H. B. Pacejka, Tire and Vehicle Dynamics, SAE Inc. 2002 [3] Henriksen, Erik K. (1973). Jig and Fixture Design Manual. New York, N.Y.: Industrial Press Inc.
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