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  • 8/10/2019 Ijierm i II 1153



    VOLUME :01 Issue 02 I Paper id-IJIERM-I-I I-1153 ,April 2014







    1Research Scholar (Ph D - Mechanical Engineering), AISECT University, Dist: Raisen, Near

    Bhopal (M P) Email: ashokgagorni@gmail.com2Professor, Mechanical Engineering Education Department, NITTTR, Bhopal (M P)

    Email: vsomkuwar@nitttrbpl.ac.in---------------------------------------------------*****----------------------------------------------------------

    ABSTRACT:Computer technology has touched all areas

    of todays life, impacting how we obtainrailway tickets, shop online and receive

    medical advice from remote location.

    Computer-based design analysis is nowadaysa common activity in most developmentprojects. When new software and

    manufacturing processes are introduced,traditional empirical knowledge is

    unavailable and considerable effort isrequired to find starting design concepts.

    This forces gear designers to go beyond thetraditional standards-based design methods.

    The results obtained are in agreement withexisting knowledge. The transformation has

    had a vast influence on gear manufacturingas well, providing process improvements that

    lead to higher gear quality and lowermanufacturing costs. However, in the case of

    the gear industry, the critical process ofGeneration and Simulation of Meshing and

    Tooth Contact Analysis (TCA) of SpiralBevel Gears remains relatively unchanged.

    Spiral bevel gears are crucial to powertransmission systems, power generation

    machines and automobiles. However, the

    design and manufacturing of spiral bevelgears are quite difficult. Currently, the majorparameters of spiral bevel gears are

    calculated, but the geometries of the gears arenot fully defined. The procedures needed to

    develop spiral bevel gear sets for a new

    product can require months of trial-and-errorwork and thousands of dollars. In view of

    increasing global competition for lowerpriced products, bevel gears are a prime

    target for the next generation of

    computerization. Answering this challenge,it has realized a new modified methodthrough a shift in the way spiral bevel gear

    development is performed.The Gleason

    face hobbing process has been widelyapplied by the gear industry. But so far, few

    papers have been found regarding exactmodelling and simulation of the tooth surface

    generations and tooth contact analysis (TCA)of spiral bevel gear sets. The developed face

    hobbing generation model is directly relatedto a physical bevel gear generator. A

    generalized and enhanced TCA algorithm isproposed. The face hobbing process has two

    categories, non-generated (Formate) andgenerated methods, applied to the tooth

    surface generation of the gear. In bothcategories, the pinion is always finished with

    the generated method. The developed toothsurface generation model covers both

    categories with left-hand and right-hand

    members. Based upon the developed theory,an advanced tooth surface generation andTCA program is developed and integrated

    into Gleason CAGE forWindows Software. Most of the truck

    manufacturers have been confronted with

  • 8/10/2019 Ijierm i II 1153



    VOLUME :01 Issue 02 I Paper id-IJIERM-I-I I-1153 ,April 2014


    ever more increasing demands on their

    products and on the development process.These demands are reflected in higher engine

    power, lower vehicle noise, higher fueleconomy and shorter lead times in

    development. In most of commercial vehicle,single stage spiral bevel gears are used in the

    rear axles. In engineering, new productdevelopment (NPD) is the complete process

    of bringing a new product to market.

    KeywordsSpiral Bevel Gear, Hypoid Gear,TCA, Computer Technology, Tooth Surface



    Gearing is one of the most criticalcomponents in a mechanical power

    transmission system, and in most industrialrotating machinery. A gear is a mechanical

    device often used in transmission systemsthat allows rotational force to be transferred

    to another gear or device. The gear teethallow force to be fully transmitted without

    slippage and depending on theirconfiguration, can transmit forces at different

    speeds, torques, and even in a differentdirection. Throughout the mechanical

    industry, many types of gears exist with eachtype of gear possessing specific benefits for

    its intended applications. Bevel gears arewidely used because of their suitability

    towards transferring power betweennonparallel shafts at any required angle or

    speed. Spiral bevel gears have curved andslope gear teeth in relation to the surface of

    the pitch cone. As a result, an oblique surface

    is formed during gear mesh which allowscontact to begin at one end of the tooth (toe)and smoothly progress to the other end of the

    tooth (heel), as shown in Fig 1a.

    Fig 1a: Spiral bevel gear mesh

    Spiral bevel gears, in comparison to straightor zerol bevel gears, have additional

    overlapping tooth action which creates asmoother gear mesh. This smooth

    transmission of power along the gear teethhelps to reduce noise and vibration that

    increases exponentially at higher speeds.Therefore, the ability of a spiral bevel gear to

    change the direction of the mechanical load,coupled with their ability to aid in noise and

    vibration reduction, make them a primecandidate for use in the automobile industry

    and others. The American GearManufacturing Association (AGMA) has

    developed standards for the design, analysis,and manufacture of bevel gears. The first step

    in any general design employing gears is tofirst predict and understand all of the

    conditions under which the gears willoperate. Most importantly are the anticipated

    loads and speeds which will affect the designof the gear. Additional concerns are the

    operating environment, lubrication,anticipated life of operation, and assembly

    processes, just to name a few. The twoprimary failure modes of gears are, one by

    tooth breakage from excessive bending stressand other by surface pitting or wear from

    excessive contact stress. The driving anddriven gears are the most important

    components of the Gear box of anyautomotive. Modelling allows the design

    engineer to let the characteristic parametersof a product drive the design of that product.


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    VOLUME :01 Issue 02 I Paper id-IJIERM-I-I I-1153 ,April 2014


    During the gear design, the main parameters

    that would describe the designed gear such asmodule, pressure angle, root radius, tooth

    thickness and number of teeth could be usedas the parameters to define the gear.

    DefinitionsIt is important that certain terms be defined

    before any testing and developmentprocedure for bevel gears is presented.

    Gear- of two gears that run together, the onewith the larger number of teeth is called the

    gear. It is the driven member of a pair ofgears.

    Pinion - the member with the smallernumber of teeth. With miter gears it is the

    driving member.

    Toe- the portion of the tooth surface at theinner end.Heel- the portion of the tooth surface at the

    outer end.Top- the upper portion of the tooth surface.

    Flank - the lower portion of the toothsurface.

    Top Land - the non-contacting surface at thetop of the tooth.

    Root Land - the non-contacting surface atthe bottom of a tooth space.

    Top Side and Bottom Side- in conventionalmachines for producing both straight and

    curved tooth bevel gears, the cutter or cuttingtools always operate on the left hand side of

    the gear blank as viewed from the front. Theterm top refers to the upper side of the tooth

    in this position, and the term bottom refers tothe lower side.

    Top Side of ToothLeft hand spiral - convex side of tooth.

    Right hand spiral - concave side of tooth.

    Bottom Side of ToothLeft hand spiral - concave side of tooth.Right hand spiral - convex side of tooth.

    The terms bottom side or top side wouldalways apply to a specific side, regardless of

    the hand of spiral, and also with straight

    bevel gears. When the forward side in the

    testing machine is running, the rotation of thepinion spindle is clockwise when viewed

    from the source of power, and the bottomside of the pinion will contact the bottom side

    of the gear. When the pinion is running in thereverse direction, the rotation is

    counter-clockwise, and the top side of thepinion will contact the top side of the gear. It

    would, therefore, be better to refer to bottomside orforward side, and top side or reverse


    When referring to a specific side of the tooth,the terms drive side or coast side are quite

    often used, but, unless a full knowledge ofthe application is available, these terms

    would not be specific. Normally the concave

    side of the pinion is called the drive side andthe convex side of the pinion is called theCoast side,but in many cases either side may

    drive. Also, with straight bevel gears, there isno concave or convex side, so it again would

    be di