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  • 有效 AGMA 13FTM26-2013 Vacuum Carburizing Large Gears

    发布日期: 2013-09 语言: 英文 来源: 新信标准
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    有效 AGMA 13FTM26-2013 Vacuum Carburizing Large Gears
    语言:英文
    适用范围:Vacuum carburizing of gears has typically been limited to partswith relatively small cross-sections. Most alloys currently in userequire oil quenching to achieve adequate surface hardness and coreproperties in large gear applications. Pit or large batch IQfurnaces with endothermic atmospheres are often used to processthis type of gear. The majority of vacuum carburizing equipment isdesigned for processing smaller parts with a high pressure gasquench. Recent equipment and process developments allow vacuumcarburizing and oil quenching of very large gears and pinions – upto 70" diameter and 7,000 lbs. Fixture design and careful processcontrol help minimize distortion, while providing the caseuniformity and surface integrity that is unique to vacuumcarburizing. This paper will discuss specific case studies involving largegears and pinions. Distortion, case hardness profiles andmicrostructures from conventional gas carburizing and vacuumcarburizing will be examined and compared.
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    适用范围:Contact fatigue and bending fatigue are two main failure modesof steel gears. Surface pitting and spalling are two common contactfatigue failures, which are due to the alternating subsurface shearstresses from the contact load between two gear mates. When a gearis in service under cyclic load, concentrated bending stressesexist at the root fillet, which is the main driver of bendingfatigue failures. Heat treatment is required to increase thehardness and strength of gears to meet the required contact andbending fatigue performance. Induction hardening is becoming morepopular due to its process consistency, reduced energy consumption,clean environment, and improved product quality. It is well knownthat an induction hardening process of steel gears can generatecompressive residual stresses in the hardened case. Compressiveresidual stresses in the hardened case of tooth flank benefit thecontact fatigue performance, and residual compression in the rootfillet benefits the bending fatigue. Due to the complex geargeometry, the residual stress distribution in the hardened case isnot uniform, and different induction hardening process can lead todifferent residual stress pattern and significant variation offatigue performance. In this paper, an innovative approach isproposed to flexibly control the magnitude of residual stress inthe regions of root fillet and tooth flank by using the concept ofpreheating prior to induction hardening. Using an external spurgear made of AISI 4340 as an example, this concept of innovativeprocess is demonstrated with finite element modeling, usingcommercial software DANTE.
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  • 有效 AGMA 13FTM22-2013 Heat Treatment of Large Components

    发布日期: 2013-09 语言: 英文 来源: 新信标准
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    有效 AGMA 13FTM22-2013 Heat Treatment of Large Components
    语言:英文
    适用范围:Large gear components can be offered in many applications suchas in marine, wind power, steel rolling mills, power plants,transportation, railroad, aircraft, cement crushers, mining and oilindustry applications. There are three important surface hardening methods used toimprove and expand the technical use of gear components. Design andmaterial engineers must decide which hardening method to use. Casehardening is normally the first choice because of the highest loadcapacity. But, case hardening also poses challenges that must beacknowledged. Therefore, it is good to know that there are threeoptions for very large components.
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    适用范围:In the design process of gearboxes, common requirements are highload capacity and low noise excitation. Reaching both goals islaborious and normally requires a trade-off. Detailed analyses ofcontact conditions and deformations are necessary. These shouldtake place in an early design stage to realize a mostlystraightforward design approach and prevent late designchanges. Focused on cylindrical gears, the paper covers an approachstarting at the first draft of a gearbox. Defining themacrogeometry of the teeth regarding load capacity calculationaccording to standards leads to a reasonable gear design. On thatbasis, the micro geometry of the teeth is specified and loaddistribution as well as noise excitation is calculated. The designparameters are interdependent so provisions have to be made toadjust each step on the remaining ones. Effects resulting fromchanging profile contact ratio under load and contact patterns notcovering the whole flank have to be regarded. The beneficial effectof a modified microgeometry is dependent on the ability toprecisely account for contact conditions and meshingclearances. To find an optimal solution for the competing goals of capacityand excitation, detailed calculation methods are required. To beable to apply latest research results, these are implemented inhighly specialized software. The task described above is handled byusing the software that was developed at the Gear Research Center(FZG) with funding by the German Research Association for Gears andTransmissions (FVA). The underlying calculation methods andanalyzed phenomena are covered.
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    适用范围:This study investigates the stresses and deflections of afloating ring gear with external splines working in a largeplanetary wheel motor of a mining truck. Such calculations carriedout with conventional engineering approaches described in popularstandards and textbooks are not comprehensive because of thecomplexity of the problem. These approaches can give us good stressnumbers for non-floating gears and some guidance about the rimthickness factor but they lack the capabilities to effectivelycalculate the deflections and their influences on the stresses,especially for floating gears. Moreover they cannot calculate anentire gearing system and the interdependent influences of thedifferent components. The model studied consists of a floating ringgear driving a torque tube. The ring gear is driven throughinternal gear meshing by three planets and it transmits the torqueto the torque tube through its external splines. The torque tubetransmits the motion to the hub and the truck tires. A nonlinearstatic analysis of the ring gear and torque tube was conducted inABAQUS. Linear 8-node hex elements and linear tetra elements wereused to model the ring gear and torque tube. External torque wasresolved into corresponding tangential force, which was thenapplied directly onto three of the ring gear's internal teeth.Contact pairs were used to capture the load transfer between thering gear and torque tube through the splines. The results showthat the deflections in the ring gear were so excessive that aboutone-tenth of the spline teeth were actually transmitting torqueagainst the common engineering understanding that only half of thespline teeth are typically engaged. The crowning of the splineteeth had also effect on the stresses though quite small comparedto the deflections. Conclusions and recommendations were made aboutthe effectiveness of the design.
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    适用范围:To date, grinding, according to the German DIN Standard 8580, is"machining with geometrically undefined cutting edges" while othermachining processes such as turning and milling are classified asprocesses with "geometrically defined cutting edges". New abrasivegrains, called PSG and developed by 3M, stand this definition onits head. For the first time, grinding wheels made with PSG, calledCubitronTM II, can claim to be made up of "geometrically definedcutting edges" as each and every grain is exactly the sameengineered shape. Hence, it might be more appropriate to talk about"micro-milling" rather than grinding. This is borne out by lookingat the resulting "flowing" chips which are akin to chips seen inmilling operations, just finer. These free-flowing chips no longer clog up the grinding wheeland, therefore, the grinding wheel remains free-cutting anddressing becomes only necessary due to loss of from rather thanloss of cutting ability. In repeated tests, this has shown todrastically reduce the risk of burning and to give consistent andpredictable results. Furthermore, tests and subsequent long termtrials under production conditions have shown that grinding timecan be cut in most cases by at least 50% in comparison to grindingwheels made of standard ceramic abrasives. Based on more than 100 carefully monitored and documented geargrinding trials, this paper will demonstrate how CubitronTM IIgrinding wheels work both in continuous generating grinding of carand truck gears, and in form grinding of large diameter gears forwind generators, for example. Furthermore, the paper will discusschip formation, filmed with high resolution slow motion; and thebenefits of the freeflowing chips in terms of resulting consistentsurface finish, superior form holding and extended dressingcycles.
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    适用范围:Proper control of distortion has become even more important onnew powertrain designs. To answer the demand for fuel­efficientvehicles, modern transmissions are built much lighter, thereforethe components of the transmission exhibit less wall thicknesswhich makes them more sensitive to distortion. Distorted gearcomponents can create noise in the transmission, require post heattreat machining processes and may even create problems duringtransmission assembly. By applying the technology of Low PressureCarburizing (LPC) and High Pressure Gas Quenching (HPGQ), thedistortion caused by heat treatment can be significantly reduced.This technology has been successfully established in serialproduction for many different gear applications. With theintroduction of 'One Piece Flow ­ heat treatment', the distortioncontrol can be further enhanced. This 'One piece Flow - heattreatment' allows for a rapid case hardening where the componentsare low pressure carburized at high temperatures (1050°C) followedby gas quenching. The components are not treated in conventionalbig batches with multiple layers, but they are treated in smallbatches consisting of one layer only. The quench intensity iscontrolled more precisely to allow for processes which arecustomized individually for each gear­component. The single­layertreatment provides Shomogenous and rapid heating of the components,Shomogenous and rapid carburizing of the components, Shomogenousand precisely controlled gas quenching. All the variations fromlayer to layer are eliminated, which leads to reductions indistortion­variation within the load. In addition, this newtechnology allows strong costs­savings for logistics. Themanufacturing­line can be completely automated since the parts are1st taken one by one from the soft machining unit, then 2nd heattreated in time with the cycle­time of soft machining("Synchronized heat treatment") and then 3rd passed down one by oneto the hard machining unit. The paper presents applications forenhanced distortion control when using 'One Piece Flow ­ heattreatment'.
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    适用范围:While eddy current technology has long been used in the testingof bar, tube, and wire stock, advances in electronics, automation,and coil design have paved the way for a new generation of testersspecifically designed for component testing applications. Thisincludes the testing of gears and bearings which go into automotiveand industrial applications. These testing systems easily integrateinto production processes allowing for in-line testing atproduction line speeds. In addition to enabling 100%of productioncomponents to be inspected, it can help monitor upstream processesnotifying operators that something is not functioning correctly.This greatly reduces scrap and warranty costs for gear and bearingmanufacturers. Eddy current crack testing is performed by passing a small pairof coil windings over a section of the component to be tested.These coil windings are small enough to test between gear teeth,and with multi-coil probes can test very complex shapes. Most cracktest applications require only one test frequency sincemost testsrequire the detection of only surface flaws. Simultaneous testingwith multiple frequencies allows for testing of both surface andsub-surface defects when inspecting non-ferromagnetic parts. While not an absolute hardness test like a Rockwell test, eddycurrent heat treat verification can achieve sorting results on parwith Rockwell testing. This has been demonstrated with both forgedand powder metal gears. Eddy current heat treat inspection coilscome in both standard encircling coil configurations and multi-coilcustom configurations. The custom configurations allow for preciselocation testing verifying that induction heating parameters werecorrectly applied. Defects to be tested include misplaced case,shallow case, short quench, delayed quench, air cooled,non-heat-treat, and ground out conditions. When performingheat-treat inspection,multiple test frequencies are used toreliably detect these various heat-treat anomalies. Eddy current testing offers fast, repeatable testing of gearsand bearings. Testing data on each component can be storedelectronically and re-analyzed off-line at a later date. Eddycurrent test instruments are designed to integratewith PLC􀀁sinmaterial handling stations to set up real-time rejectioncapabilities. These are all features that complement modern QCrequirements.
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    适用范围:The unique requirements of an electroplatable superabrasive CBNgrit used in profile grinding of hardened steel gears as well asthe attributes and grinding behavior of a new CBN developedspecifically for this application are discussed. Profile geargrinding parameters were simulated in through-hardened AISI 4140steel (56 HRC) and the grinding performance of the newCBNwascompared against a competitiveCBNgrade widely used in theapplication. Consistent with field criteria, grinding performancewas characterized based on occurrence of ‘burn' or ‘form' failure.The ‘burn' or metallurgical phase transformation failure wasdetected by Barkhausen Noise Analysis (BNA) and corroborated bymicrostructural and microhardness evaluations. The ‘form' failurewas simulated by tracking average radial wheel wear to a thresholdvalue where form loss was expected to occur. Grinding testsindicate that the new CBN grit can grind 35% more parts compared tothe competitive CBN grade before burn failure. In addition, the newCBN displayed a lower wear rate. The new CBN grade also exhibited aunique ability to grind with lower grinding power, resulting in anear constant BNA response on the ground surface throughout thetest. This impliedminimal microstructural change on the ground partfrom start to end of the test compared to the progressive softeningof ground surface noticed with the competitive CBN.
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    适用范围:Induction hardening of gear teeth is well known for itschallenges, but also for its potential for improved quality andprocess control. For complex geometric parts like gears, the powerdensity and induction frequency need to be adjusted very preciselyto achieve the required hardening pattern. Since 1940s it is knownthat working with two simultaneous frequencies (1-15 kHz and200-20000 kHz) is the optimal way to heat a geared part tohardening temperature. The key point in this process is that themedium frequency (about 10 kHz) affects primarily the tooth rootand the high frequency affects first of all the tip of the toothand the flanks. The right combination of the power densities ofmedium- and high frequency energy values and the heating time arethe crucial factors to reach a contour true heating pattern and,thereby, a contour true hardening pattern. The authors willdescribe the state of the art of induction hardening of gears withsimultaneous dual frequency using some examples of use and presentthe possibilities to manipulate the hardening pattern in a positiveway for different gear geometries.
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  • 有效 AGMA 11FTM19-2011 Convoloid Gearing Technology - The Shape Of The Future

    发布日期: 2011-10 语言: 英文 来源: 新信标准
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    语言:英文
    适用范围:Since the invention of the involute curve and the applicationthereof to gearing, the world has embraced and developed this typeof gear tooth form to a very high degree of engineering andmanufacturing excellence. Improvements in recent years have beenrelatively modest, since this form has been so rigorously studiedand applied. The long term adoption of the involute is rooted inlarge part to the simplicity of its tools and field operation.Straight sided tools and conjugacy, even with limited changes incenter distance, were consistent with the industrial revolution ofthe 18th, 19th, and 20th centuries, and the mechanically basedmachine tools of these ages. The recent ubiquitous nature ofcomputers and CNC machinery exacerbates the cost effective freedomto optimize many parameters affecting gear tooth forms. Convoloidis a new gear tooth form capable of increasing torques 20% to 35%over those of conventionally designed involute pairs. The form iscomputer optimized, is compatible with the world's existing capitalasset infrastructure, and mirrors the manufacturing sequences,processes and basic production costs of involute gears. The resultis a major enhancement in gear drive system power density and costreduction for a given power requirement. Convoloid gearing istotally scalable and is used in parallel axis helical, planetary,and other configurations. The design, rating (surface durabilityand bending), flash temperature analysis and other importantperformance criteria for this technology along with themanufacturing and inspection protocols in keeping with AGMA and ISOspecifications will be discussed. Test results confirming many ofthe superior load carrying characteristics of this tooth form willbe presented. Side by side comparisons of involute versus Convoloiddesigns and test performance results will be presented confirmingthe validity of the theory.
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  • 有效 AGMA 11FTM18-2011 Longitudinal Tooth Contact Pattern Shift

    发布日期: 2011-10 语言: 英文 来源: 新信标准
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    有效 AGMA 11FTM18-2011 Longitudinal Tooth Contact Pattern Shift
    语言:英文
    适用范围:After a period of operation turbo gears may exhibit a change inthe tooth contact pattern, reducing full face width contact, andthereby increasing the risk of tooth distress due to the decreasedloaded area of the teeth. The phenomena may or may not occur. Insome units the shift is more severe than others and has beenobserved in cases where there is as little as 50,000 hours ofoperation. In other cases there is no evidence of any change forunits in operation for more than 100,000 hours. This condition hasbeen observed primarily in single helical gears with low helixangles (10-13?). All recorded observations have been with casecarburized hardened and ground gear sets. This paper describes thephenomena observed among some of many installed high speed gearunits in field operation that have been inspected. The authors havenot found any written material describing this behavior and uponfurther investigation suggest a possible cause. Left unchecked andwithout corrective action, this occurrence may result in toothbreakage.
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    适用范围:Micropitting is a surface fatigue phenomenon on highly loadedcase hardened gear flanks. Main contributors are local stress,surface roughness, sliding speed and lube oil properties. Todetermine the lube oil performance with respect to micropitting,different test methods have been established in the past. Actualproposals are evaluated for adopting suitable calculation methodsfor micropitting resistance to the ISO 6336 gear rating standards.But is micropitting necessarily a damage in any case? Practicalexperience shows, that a certain level of micropitting is actuallyacceptable, leading to even more favorable load distribution andcan end up in a stable flank condition performing without problemsfor the designed service live. The paper describes testing,calculation approaches and application to practical cases withrespect to micropitting on wind turbine and high speed gears andperennial observations and experience.
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    适用范围:There is no abstract currently available for this document
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    适用范围:The load distribution measurement of gear teeth and thedetermination of the face load factor for contactstressKHβ are of fundamental importance for thegear manufacturing industry. The factorKHß is ameasure for theuniformity of the load distribution along the face width. Thecloser this factor is to one the more uniform is the loaddistributed along the face width. During the design phase thisfactor is determined with the help of approximation equations aswell as finite element analysis and is used to dimension the flankmodifications. In addition KHß is used in thelifetime calculations according to DIN 3990 and ISO 6336 requiredby the certification societies. In the testing phase this factor isexperimentally determined by strain measurements of tooth filletsin order to verify the load distribution calculations and thesuitability of the used modifications. For spur gears with no helix angle the interpretation of themeasurements to a face load factor is intuitively easy. For helicalgears, more frequently used in big gearboxes, the determination ofthe factor gets tougher. The line of contact of these gears runsinclined over the face width of the tooth flanks. In this contextthe question arises whether the face load factor is evaluated alongthe face width or along the path of contact. The evaluation of the measured values and the interpretation toa face load factor is a complex challenge and is not standardized.Alarge number of publications make suggestions; however, thesesuggestions differ to a large degree. The standardisation of theload distribution evaluation and a uniform definition ofKHß for helical gears enable a safer design forthemanufacturers and an easier comparability of the results for thecustomers. The paper compares the different suggestions to theKHß definition and will derive a suitable definition forthe calculation methods in DIN 3990 and ISO 6336.
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    适用范围:FOREWORD In 1926 the AGMA adopted a recommended practice for gearing nomenclature, terms and definition"s.ic1t"included some symbols and abbreviations. A complete revision elf terms and definitions by the AGMA Nomenclature Committee was AGMA 112.02 issued in October, 1948. This later became AGMA 112.03, and . American Standard B6.J0-1954, with ASME as a co-spoonsor. A separate project dealing with Letter Symbols for Gear Engineering appeared in 1943 as AGMA 111.01, later becoming AGMA 111.03 and American Standard 86.5-1954. Abbreviations for Gearing was another separate project released as AGMA 116.01 in 1955. Most of these abbreviations were already listed in American Standard Z32. 13-1950 ''Abbreviations for Use on Drawings", and it was, therefore, unnecessary to process gearing abbreviations as a separate American Standard. The number of abbreviations used in gearing has intentionally been kept very small to permit memorizing without the "need to refer to the standard. AGMA Standard 112.04, "Gear Nomenclature-Terms, Defiriitions, Symbols and Abbreviations,'' was a· complete revision and integraiion of ihe thre.e standards previously mentioned. Because of the widespread acceptance of the pre.vious s_tandards, changes were.·, kept to a minimum. The standard in this form was approved by the AGMA Membership as of April 25, 1965. This standard, AGMA 112.05, includes several revisions to keep it abreast with current gearing techniques. It has been approved by Standards Committee B6, Gears, the Co-Secretariats and the American National Standards Institute as of February 3, 1976, and designated ANSI B6.14-1976.
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  • 有效 AGMA 1106A-1997(R2009) Tooth Proportions For Plastic Gears

    发布日期: 2009-05 语言: 英文 来源: 新信标准
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    有效 AGMA 1106A-1997(R2009) Tooth Proportions For Plastic Gears
    语言:英文
    适用范围:Presents a new basic rack, AGMA PT, which, with its full roundfillet, may be preferred in many applications of gears made fromplastic materials. It contains a description, with equations andsample calculations, of how the proportions of a spur or helicalgear may be derived from the design tooth thickness and the basicrack data. In several annexes, there are discussions of possiblevariations from the basic rack and also a procedure for definingtooth proportions without using the basic rack concept.
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