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One process for hard finishing gears is generating gear grinding. Due to its high process efficiency, generating gear grinding has replaced other grinding processes such as profile grinding in batch production of small- and middle-sized gears. Yet despite the wide industrial application of generating gear grinding, the process design is based on experience along with time- and cost-intensive trials. The science-based analysis of generating gear grinding demands a high amount of time and effort, and only a few published scientific analyses exist. In this report a thermo-mechanical process model that describes influences on the surface zone in generating gear grinding is introduced.
The grinding of gears with dish wheels (Maad type grinding machines) is widely viewed as the most precise method of gear grinding because of the very short and simple kinematic links between the gear and the tool, and also because the cutting edges of the wheels represent planar surfaces. However, in this grinding method, depending on the parameters of the gears and one of the adjustments (such as the number of teeth encompassed by the grinding wheels), so-called overtravel at the tip or at the root of the teeth being ground generally occurs. When this happens, machining with only one wheel takes place. As a result, the profile error and the length of the generating path increases while productivity decreases.
Dressable vitrified bond CBN grinding tools combine the advantages of other common tool systems in generating gear grinding. Yet despite those technological advantages, there is only a small market distribution of these grinding tools due to high tool costs. Furthermore, scant literature exists regarding generating gear grinding with dressable CBN. This is especially true regarding the influence of the grinding tool system on manufacturing-related component properties. The research objective of this report is to determine the advantages of dressable CBN tools in generating gear grinding.
The merits of CBN physical characteristics over conventional aluminum oxide abrasives in grinding performance are reviewed. Improved surface integrity and consistency in drive train products can be achieved by the high removal rate of the CBN grinding process. The influence of CBN wheel surface conditioning procedure on grinding performance is also discussed.
Power train designs which employ gears with cone angles of approximately 2 degrees to 5 degrees have become quite common. It is difficult, if not impossible, to grind these gears on conventional bevel gear grinding machines. Cylindrical gear grinding machines are better suited for this task. This article will provide an overview of this option and briefly introduce four grinding variation possibilities.
Until recently, form gear grinding was conducted almost exclusively with dressable, conventional abrasive grinding wheels. In recent years, preformed, plated Cubic Boron Nitride (CBN) wheels have been introduced to this operation and a considerable amount of literature has been published that claim that conventional grinding wheels will be completely replaced in the future. The superior machining properties of the CBN wheel are not disputed in this paper.
This article investigates fillet features consequent to tooth grinding by generating methods. Fillets resulting from tooth cutting and tooth grinding at different pressure angles and with different positions of grinding wheel are compared. Ways to improve the final fillet of the ground teeth with regard to tooth strength and noise, as well as the grinding conditions, are shown. "Undergrinding" is defined and special designs for noiseless gears are described.
This article shows the newest developments to reduce overall cycle time in grinding wind power gears, including the use of both profile grinding and threaded wheel grinding.
Excessive machine tool vibration during a precision grinding operation can result in poor workpiece quality in the form of chatter, rough finishes, burn, etc. One possible reason for excessive vibration is directly associated with the relationship between natural frequencies of a machine tool system and the operating speed of the grinding wheel spindle.
Because of the better thermal conductivity of CBN abrasives compared to that of conventional aluminum oxide wheels, CBN grinding process, which induces residual compressive stresses into the component, and possibly improves the subsequent stress behavior. This thesis is the subject of much discussion. In particular, recent Japanese publications claim great advantages for the process with regard to an increased component load capacity, but do not provide further details regarding the technology, test procedures or components investigated. This situation needs clarification, and for the this reason the effect of the CBN grinding material on the wear behavior and tooth face load capacity of continuously generated ground gears was further investigated.
It isn't for everyone, but... Within the installed base of modern CNC gear profile grinding machines (approximately 542 machines worldwide), grinding from the solid isn't frequent, but a growing number of gear profile grinder users are applying it successfully using CBN-plated wheels.
Gear grinding is one of the most expensive and least understood aspects of gear manufacturing. But with pressures for reduced noise, higher quality and greater efficiency, gear grinding appears to be on the rise.
In the quest for ever more exacting and compact commercial gears, precision abrasives are playing a key production role - a role that can shorten cycle time, reduce machining costs and meet growing market demand for such requirements as light weights, high loads, high speed and quiet operation. Used in conjunction with high-quality grinding machines, abrasives can deliver a level of accuracy unmatched by other manufacturing techniques, cost-effectively meeting AGMA gear quality levels in the 12 to 15 range. Thanks to advances in grinding and abrasive technology, machining has become one of the most viable means to grind fast, strong and quiet gears.
This article deals with certain item to be taken into consideration for gear grinding, common problems that arise in gear grinding and their solutions. The discussion will be limited to jobbing or low-batch production environments, where experimental setup and testing is not possible for economic and other reasons.
Modern gearboxes are characterized by high torque load demands, low running noise and compact design. In order to fulfill these demands, profile and lead modifications are being applied more often than in the past. This paper will focus on how to produce profile and lead modifications by using the two most common grinding processes—threaded wheel and profile grinding. In addition, more difficult modifications—such as defined flank twist or topological flank corrections—will also be described in this paper.
When gears are case-hardened, it is known that some growth and redistribution of stresses that result in geometric distortion will occur. Aerospace gears require post case-hardening grinding of the gear teeth to achieve necessary accuracy. Tempering of the case-hardened surface, commonly known as grinding burn, occurs in the manufacturing process when control of the heat generation at the surface is lost.
Grinding is a technique of finish-machining, utilizing an abrasive wheel. The rotating abrasive wheel, which id generally of special shape or form, when made to bear against a cylindrical shaped workpiece, under a set of specific geometrical relationships, will produce a precision spur or helical gear. In most instances the workpiece will already have gear teeth cut on it by a primary process, such as hobbing or shaping. There are essentially two techniques for grinding gears: form and generation. The basic principles of these techniques, with their advantages and disadvantages, are presented in this section.
Generating gear grinding is one of the most important finishing processes for small and medium-sized gears, its process design often determined by practical knowledge. Therefore a manufacturing simulation with the capability to calculate key values for the process — such as the specific material removal rate — is developed here. Indeed, this paper presents first results of a model for a local analysis of the value. Additionally, an empirical formula — based on a multiple regression model for a global value describing the process — is provided.
Flexibility and productivity are the keywords in today’s grinding operations. Machines are becoming more flexible as manufacturers look for ways to produce more parts at a lower cost. What used to take two machines or more now takes just one.
In order to improve load-carrying capacity and noise behavior, gears usually have profile and lead modifications. Furthermore, in gears where a specified tooth-flank load application direction (for drive and coast flanks) is a design enhancement, or even compulsory, the asymmetric tooth profile is a further solution. Nowadays, many gears need to be hard finished. Continuous generating grinding offers a very high process efficiency, but is this process able to grind all modifications, especially asymmetric gears? Yes, it is!
The goal of gear drive design is to transit power and motion with constant angular velocity. Current trends in gear drive design require greater load carrying capacity and increased service life in smaller, quieter, more efficient gearboxes. Generally, these goals are met by specifying more accurate gears. This, combined with the availability of user-friendly CNC gear grinding equipment, has increased the use of ground gears.
This paper presents the results of a study performed to measure the change in residual stress that results from the finish grinding of carburized gears. Residual stresses were measured in five gears using the x-ray diffraction equipment in the Large Specimen Residual Stress Facility at Oak Ridge National Laboratory.
The benefits of ground gears are well known. They create less noise, transmit more power and have longer lives than non-ground gears. But grinding has always been thought of as an expensive process, one that was necessary only for aerospace or other high-tech gear manufacturing.
The bevel gear grinding process, with conventional wheels, has been limited to applications where the highest level of quality is required.
New divisions, open houses and the continued rise of the Industrial Internet of Things - There's been a lot going on in gear grinding in the past year.
Recent breakthroughs in profile grinding software are helping Anderson Precision Gears and others meet wind power’s insatiable appetite for faster production of large, high-quality gears.
Modern manufacturing processes have become an ally of the product designer in producing higher quality, higher performing components in the transportation industry. This is particularly true in grinding systems where the physical properties of CBN abrasives have been applied to improving cycle times, dimensional consistency, surface integrity and overall costs. Of these four factors, surface integrity offers the greatest potential for influencing the actual design of highly stressed, hardened steel components.
The fundamental purpose of gear grinding is to consistently and economically produce "hard" or "soft" gear tooth elements within the accuracy required by the gear functions. These gear elements include tooth profile, tooth spacing, lead or parallelism, axial profile, pitch line runout, surface finish, root fillet profile, and other gear geometry which contribute to the performance of a gear train.
For over 50 years, grinding has been an accepted method of choice for improving the quality of gears and other parts by correcting heat treat distortions. Gears with quality levels better than AGMA 10-11 or DIN 6-7 are hard finished, usually by grinding. Other applications for grinding include, but are not limited to, internal/external and spur/helical gear and spline forms, radius forms, threads and serrations, compressor rotors, gerotors, ball screw tracks, worms, linear ball tracks, rotary pistons, vane pump rotators, vane slots, and pump spindles.
Grinding of bevel and hypoid gears creates on the surface a roughness structure with lines that are parallel to the root. Imperfections of those lines often repeat on preceding teeth, leading to a magnification of the amplitudes above the tooth mesh frequency and their higher harmonics. This phenomenon is known in grinding and has led in many cylindrical gear applications to an additional finishing operation (honing). Until now, in bevel and hypoid gear grinding, a short time lapping of pinion and gear after the grinding operation, is the only possibility to change the surface structure from the strongly root line oriented roughness lines to a diffuse structure.
This paper acknowledges the wide variety of manufacturing processes--especially in grinding--utlized in the production of bevel gears...
The latest machines, tooling and technology for gear grinding were featured at IMTS 2012.
Bevel gear manufacturers live in one of two camps: the face hobbing/lapping camp, and the face milling/grinding camp.
This machine concept facilitates highly productive profile grinding for large workpieces. The range for external and internal gears comprises models for manufacturing workpieces up to 2,000 millimeters – for industrial gear units, wind power, and marine propulsion applications
Instances of damage to discontinuous form ground and surface-hardened gears, especially of large scale, have recently increased. This may be attributed partly to a faulty grinding process with negative effects on the surface zones and the surface properties.
The hobbing and generation grinding production processes are complex due to tool geometry and kinematics. Expert knowledge and extensive testing are required for a clear attribution of cause to work piece deviations. A newly developed software tool now makes it possible to simulate the cutting procedure of the tool and superimpose systematic deviations on it. The performance of the simulation software is illustrated here with practical examples. The new simulation tool allows the user to accurately predict the effect of errors. With this knowledge, the user can design and operate optimal, robust gearing processes.
Liebherr is well-known as one of the world’s largest privately owned companies — a titan in heavy industry specializing in cranes, trucks and mammoth earth moving and mining equipment.
In comparison to the visionary Industry 4.0 - or the Fourth Industrial Revolution - the machine tool industry can appear rather down-to-earth.
An analysis of possibilities for the selection of tool geometry parameters was made in order to reduce tooth profile errors during the grinding of gears by different methods. The selection of parameters was based on the analysis of he grid diagram of a gear and a rack. Some formulas and graphs are presented for the selection of the pressure angle, module and addendum of the rack-tool. The results from the grinding experimental gears confirm the theoretical analysis.
Much of the existing guidelines for making large, high-performance gears for wind turbine gearboxes exhibit a need for improvement. Consider: the large grinding stock used to compensate for heat treatment distortion can significantly reduce manufacturing productivity; and, materials and manufacturing processes are two other promising avenues to improvement. The work presented here investigates quenchable alloy steels that, combined with specifically developed Case-hardening and heat treatment processes, exhibits reduced distortion and, in turn, requires a smaller grinding stock.
When hardened steel components are ground, there is always the possibility of damage to the steel in the form of residual stress or microstructural changes. Methods for detecting this sort of damage have always had one or more drawbacks, such as cost, time, complexity, subjectivity, or the use of hazardous chemicals.
When Dr. Hermann J. Stadtfeld speaks, people tend to listen. Considered one of the world’s foremost experts on bevel gears, Stadtfeld, the vice president of bevel gear technology at Gleason, recently revealed several cutting-edge advancements that the company has been working on.
Whether you spent time at Gear Expo in Indianapolis or EMO in Hannover, there was certainly new technology attracting attention. Machine tools are faster, more efficient and can integrate numerous functions in a single setup. Grinding technology is turning science upside down and inside out with high-speed removal rates and increased throughput.
The grinding/abrasives market is rapidly changing, thanks to new technology, more flexibility and an attempt to lower customer costs. Productivity is at an all-time high in this market, and it’s only going to improve with further R&D. By the time IMTS 2014 rolls around this September, the gear market will have lots of new toys and gadgets to offer potential customers. If you haven’t upgraded any grinding/abrasives equipment in the last five years, now might be a good time to consider the investment.
The quality of a gear and its performance is determined by the following five parameters, which should be specified for each gear: Pitch diameter, involute form, lead accuracy, spacing accuracy, and true axis of rotation. The first four parameters can be measured or charted and have to be within tolerance with respect to the fifth. Pitch diameter, involute, lead, and spacing of a gear can have master gear quality when measured or charted on a testing machine, but the gear might perform badly if the true axis of rotation after installation is no longer the same one used when testing the gear.
Grinding in one form or another has been used for more than 50 years to correct distortions in gears caused by the high temperatures and quenching techniques associated with hardening. Grinding improves the lead, involute and spacing characteristics. This makes the gear capable of carrying the high loads and running at the high pitch line velocities required by today's most demanding applications. Gears that must meet or exceed the accuracy requirements specified by AGMA Quality 10-11 or DIN Class 6-7 must be ground or hard finished after hear treatment.
Borazon is a superabrasive material originally developed by General Electric in 1969. It is a high performance material for machining of high alloy ferrous and super alloy materials. Borazon CBN - Cubic Born Nitride - is manufactured with a high temperature, high pressure process similar to that utilized with man-made diamond. Borazon is, next to diamond, the hardest abrasive known; it is more than twice as hard as aluminum oxide. It has an extremely high thermal strength compared to diamond. It is also much less chemically reactive with iron, cobalt or nickel alloys.
This paper intends to determine the load-carrying capacity of thermally damaged parts under rolling stress. Since inspection using real gears is problematic, rollers are chosen as an acceptable substitute. The examined scope of thermal damage from hard finishing extends from undamaged, best-case parts to a rehardening zone as the worst case. Also, two degrees of a tempered zone have been examined.
Guidelines are insurance against mistakes in the often detailed work of gear manufacturing. Gear engineers, after all, can't know all the steps for all the processes used in their factories.
When you push 850 horsepower and 9,000 rpm through a racing transmission, you better hope it stands up. Transmission cases and gears strewn all over the racetrack do nothing to enhance your standing, nor that of your transmission supplier.
In order to grind gears burn-free and as productively as possible, a better understanding of the process is required.
A considerable improvement in the performance of the machining of hard to grind materials can be achieved by means of CBN wheels.
Machine tool companies are expanding capabilities to better accommodate the changing face of manufacturing. Customers want smaller-sized equipment to take up less valuable floor space, multifunctional machines that can handle a variety of operations and easy set-up changes that offer simplified operation and maintenance.
In conventional gear grinders, grinding wheels with Alundum grains and a hardness of about 2000 HV have been used for finishing steel gears with hardnesses up to about 1000HV. In this case, the accuracy of the gears ground is greatly affected by wear of the grinding wheel because the difference in hardness is comparatively small when the gears are fully hardened.
This paper introduces the latest process developments for the hard-finishing of gears, specifically in regard to controlling the so-called flank twist.
New freedom of motion available with CNC generators make possible improving tooth contact on bevel and hypoid gears. Mechanical machines by their nature are inflexible and require a special mechanism for every desired motion. These mechanisms are generally exotic and expensive. As a result, it was not until the introduction of CNC generators that engineers started exploring motion possibilities and their effect on tooth contact.
With increasingly smaller returns from improving the speed of the actual gear grinding process, improving your setup time has become a primary way to keep improving efficiency. Here's the latest on how you can do that today.
Looking for some simple yet useful advice heading into IMTS 2016? Never second guess your machine tool investment. Flexibility is a mandatory requirement in gear manufacturing today. Accuracy, reliability and efficiency must improve with each new machine tool purchase. Innovation is always the end game. So it comes as no surprise that IMTS 2016 attendees will have plenty of gear grinding technologies to consider this fall.
Could you explain to me the difference between spiral bevel gear process face hobbing-lapping, face milling-grinding and Klingelnberg HPG? Which one is better for noise, load capacity and quality?
For two days in Saline, Michigan, Liebherr's clients, customers and friends came together to discuss the latest gear products and technology. Peter Wiedemann, president of Liebherr Gear Technology Inc., along with Dr.-Ing. Alois Mundt, managing director, Dr.-Ing. Oliver Winkel, head of application technology, and Dr.-Ing. Andreas Mehr, technology development shaping and grinding, hosted a variety of informative presentations.
Analysis of helical involute gears by tooth contact analysis shows that such gears are very sensitive to angular misalignment leading to edge contact and the potential for high vibration. A new topology of tooth surfaces of helical gears that enables a favorable bearing contact and a reduced level of vibration is described. Methods for grinding helical gears with the new topology are proposed. A TCA program simulating the meshing and contact of helical gears with the new topology has been developed. Numerical examples that illustrate the proposed ideas are discussed.
"Documentation is not a Substitute for an Intuitive Interface." The author explores the development of modern controls for a CNC gear grinding machine.
For maximum life in carburized and ground gearing, I have been advised that fully grinding a radius into the root gives maximum resistance against fatigue failures. Others have advised that a hobbed and unground radius root form is best. Which is best, and why?
A different method to produce a sample that has a very consistent amount of thermal damage.
A reader wants to know: Are profile ground and hobbed globoidal worm sets better than multi-axis CNC generated globoidal worm gear sets for reduction of noise and vibration?
Ground bevel and hypoid gears have a designed motion error that defines parts of their NVH behavior. The surface structure is defined by the hard finishing process.
In the design process of transmissions, one major criterion is the resulting noise emission of the powertrain due to gear excitation. Within the past years, much investigation has shown that the noise emission can be attributed to quasi-static transmission error. Therefore, the transmission error can be used for a tooth contact analysis in the design process, as well as a characteristic value for quality assurance by experimental inspections.
Gear Technology interviews Scott Yoders of Liebherr about the latest gear machining technologies of relevance to automotive manufacturers.
THE FINAL CHAPTER This is the last in the series of chapters excerpted from Dr. Hermann J. Stadtfeld's Gleason Bevel Gear Technology - a book written for specialists in planning, engineering, gear design and manufacturing. The work also addresses the technical information needs of researchers, scientists and students who deal with the theory and practice of bevel gears and other angular gear systems. While all of the above groups are of course of invaluable importance to the gear industry, it is surely the students who hold the key to its future. And with that knowledge it is reassuring to hear from Dr. Stadtfeld of the enthusiastic response he has received from younger readers of these chapter installments.
When a customer needed gears delivered in three weeks, here’s how Brevini Wind got it done.
Hofler Rapid 6000 Makes North American Debut at Highway Machine Company.
Hard Gear Finishing (HGF), a relatively new technology, represents an advance in gear process engineering. The use of Computer Numerical Controlled (CNC) equipment ensures a high precision synchronous relationship between the tool spindle and the work spindle as well as other motions, thereby eliminating the need for gear trains. A hard gear finishing machine eliminates problems encountered in two conventional methods - gear shaving, which cannot completely correct gear errors in gear teeth, and gear rolling, which lacks the ability to remove stock and also drives the workpiece without a geared relationship to the master rolling gear. Such a machine provides greater accuracy, reducing the need for conventional gear crowning, which results in gears of greater face width than necessary.
Profitable hard machining of tooth flanks in mass production has now become possible thanks to a number of newly developed production methods. As used so far, the advantages of hard machining over green shaving or rolling are the elaborately modified tooth flanks are produced with a scatter of close manufacturing tolerances. Apart from an increase of load capacity, the chief aim is to solve the complex problem of reducing the noise generation by load-conditioned kinematic modifications of the tooth mesh. In Part II, we shall deal with operating sequences and machining results and with gear noise problems.
Tom Lang of Kapp Technologies shares his views on the trends affecting ground gears.
New machine promises DIN 2 accuracy and unique features at low cost.
The honing of gears - by definition - facilitates ease of operation, low noise and smoother performance in a transmission. Honing also contributes to reduced friction in the powertrain. Both the intense cutting (roughing process) as well as the functionally fine- finishing of transmission gears can be performed in one setup, on one machine.
This paper initially defines bias error—the “twisted tooth phenomenon.” Using illustrations, we explain that bias error is a by-product of applying conventional, radial crowning methods to produced crowned leads on helical gears. The methods considered are gears that are finished, shaped, shaved, form and generated ground. The paper explains why bias error occurs in these methods and offers techniques used to limit/eliminate bias error. Sometimes, there may be a possibility to apply two methods to eliminate bias error. In those cases, the pros/cons of these methods will be reviewed.
After shaping or hobbing, the tooth flanks must be either chamfered or duburred. Here it is paramount that the secondary burr produced will not be formed into the flank, but to the face of the gear, because during hardening, the secondary burr will straighten up and, due to its extreme hardness, will lead to excessive tool wear.
The GS:TE-LM thread grinder from Drake Manufacturing is fitted with a robot load/unload system that provides maximum throughput for high-volume production of ground threads.
Gleason 350GMS helps put higher quality, more reliable gears into its next-generation TC10 automatic transmission.
When designing hardened and ground spur gears to operate with minimum noise, what are the parameters to be considered? should tip and/or root relief be applied to both wheel and pinion or only to one member? When pinions are enlarged and he wheel reduced, should tip relief be applied? What are the effects on strength, wear and noise? For given ratios with enlarged pinions and reduced wheels, how can the gear set sized be checked or adjusted to ensure that the best combination has been achieved?
Cubitron II wheels are put to the test in this case study.
The complete Industry News section from the July 2014 issue of Gear Technology.
Every so often manufacturing is jolted out of its inertia by a transformative technology – one that fundamentally changes not only the way products are made, but also the economics of the business.
Non-uniform gear wear changes gear topology and affects the noise performance of a hypoid gear set. The aggregate results under certain vehicle driving conditions could potentially result in unacceptable vehicle noise performance in a short period of time. This paper presents the effects of gear surface parameters on gear wear and the measurement/testing methods used to quantify the flank wear in laboratory tests.
Previews of manufacturing technology related to gears that will be on display at IMTS 2012.
Gear noise associated with tooth surface topography is a fundamental problem in many applications. Operations such as shaving, gear grinding and gear honing are usually used to finish the gear surface. Often, gears have to be treated by a combination of these operations, e.g. grinding and honing. This is because gear honing operations do not remove enough stock although they do create a surface lay favorable for quiet operation. See Fig. 1 for typical honing process characteristics. Gear grinding processes, on the other hand, do remove stock efficiently but create a noisy surface lay.
Spur gear surface endurance tests were conducted to investigate CBN ground AISI 9310 spur gears for use in aircraft applications, to determine their endurance characteristics and to compare the results with the endurance of standard vitreous ground AISI 9310 spur gears. Tests were conducted with VIM-VAR AISI 9210 carburized and hardened gears that were finish ground with either CBN or vitreous grinding methods. Test conditions were an inlet oil temperature of 320 K (116 degree F), an outlet oil temperature of 350 K (170 degree F), a maximum Hertz stress of 1.71 GPa (248 ksi), and a speed of 10,000 rpm. The CBN ground gears exhibited a surface fatigue life that was slightly better than the vitreous ground gears. The subsurface residual stress of the CBN ground gears was approximately the same as that for the standard vitreous ground gears for the CBN grinding method used.
Question: When evaluating charts from a gear inspection machine, it is sometimes found that the full length of the profile traces vary, and that sometimes they are less than the length of active profile (above start of active profile-SAP) by up to 20%. This condition could be caused by a concentricity error between tooth grinding and shaping, or by unequal stock removal when grinding. (See Fig. 1.) Is it possible that some of the variation is coming from the inspection machine? How can variation from the inspection machine be reduced?
When it comes to setting the standard for gear making, the auto industry often sets the pace. Thus when automakers went to grinding after hardening to assure precision, so did the machine shops that specialize in gearing. But in custom manufacturing of gears in small piece counts, post-heat treat grinding can grind away profits too.
When manufacturing powder metal (PM) gears lead crowning is not achievable in the compaction process. This has to be accomplished either by shaving, grinding or honing. Each of these processes has their merits and draw backs. When employing rolling using a roll burnishing machine lead crowning can be accomplished but due to errors in profile a hard finishing operation such as grinding is used by the industry. In this paper a helical PM gear that has sufficient tolerance class after rolling has been tested in a test rig for durability and the wear has been studied.
C & B Machinery Meets Rigorous Demands with Installation of Manufacturing Cell.
In order to increase the load carrying capacity of hardened gears, the distortion of gear teeth caused by quenching must be removed by precision cutting (skiving) and/or grinding. In the case of large gears with large modules, skiving by a carbide hob is more economical than grinding when the highest accuracy is not required.
In the past, the blades of universal face hobbing cutters had to be resharpened on three faces. Those three faces formed the active part of the blade. In face hobbing, the effective cutting direction changes dramatically with respect to the shank of the blade. Depending on the individual ratio, it was found that optimal conditions for the chip removal action (side rake, side relief and hook angle) could just be established by adjusting all major parameters independently. This, in turn, results automatically in the need for the grinding or resharpening of the front face and the two relief surfaces in order to control side rake, hook angle and the relief and the relief angles of the cutting and clearance side.
Grinding fluids from Norton|Saint-Gobain, digital micrometer from Mahr, grinding centers from Haas Multigrind, updated software from KISSsoft.
Traditionally, high-quality gears are cut to shape from forged blanks. Great accuracy can be obtained through shaving and grinding of tooth forms, enhancing the power capacity, life and quietness of geared power transmissions. In the 1950s, a process was developed for forging gears with teeth that requires little or no metal to be removed to achieve final geometry. The initial process development was undertaken in Germany for the manufacture of bevel gears for automobile differentials and was stimulated by the lack of available gear cutting equipment at that time. Later attention has turned to the forging of spur and helical gears, which are more difficult to form due to the radial disposition of their teeth compared with bevel gears. The main driver of these developments, in common with most component manufacturing, is cost. Forming gears rather than cutting them results in increased yield from raw material and also can increase productivity. Forging gears is therefore of greater advantage for large batch quantities, such as required by the automotive industry.
New grinding machines, multi-tasking machines, gear software and tools for gear manufacturers.
Manufacturing involute gears using form grinding or form milling wheels are beneficial to hobs in some special cases, such as small scale production and, the obvious, manufacture of internal gears. To manufacture involute gears correctly the form wheel must be purpose-designed, and in this paper the geometry of the form wheel is determined through inverse calculation. A mathematical model is presented where it is possible to determine the machined gear tooth surface in three dimensions, manufactured by this tool, taking the finite number of cutting edges into account. The model is validated by comparing calculated results with the observed results of a gear manufactured by an indexable insert milling cutter.
Vibration and noise from wind turbines can be significantly influenced - and therefore reduced - by selecting suitable gearing modifications. New options provided by manufacturers of machine tools and grinding machines, and especially state-of-the-art machines and controls, provide combined gearing modifications - or topological gearing corrections - that can now be reliably machined. Theoretical investigations of topological modifications are discussed here with the actual machining and their possible use.
High demands for cost-effectiveness and improved product quality can be achieved via a new low pressure carburizing process with high pressure gas quenching. Up to 50% of the heat treatment time can be saved. Furthermore, the distortion of the gear parts could be reduced because of gas quenching, and grinding costs could be saved. This article gives an overview of the principles of the process technology and the required furnace technology. Also, some examples of practical applications are presented.
Traditionally, a worm or a multi-stage gear box has been used when a large speed ratio is required. However, such boxes will become obsolete as size and efficiency become increasingly important considerations for a modern transmission. The single-enveloped worm gear has a maximum speed ratio of only 40 to 60. Its efficiency is only 30 to 60 per cent. The necessity of using bronze for the worm gear and grinding nitoalloy steel for the worm drives up material and manufacturing costs.
When parts you manufacture pass through numerous processes such as deep hole drilling, machining, hobbing and grinding, a CMM is essential when your customers require 100 percent in-process and final inspection.
Beveloid gears are used to accommodate a small shaft angle. The manufacturing technology used for beveloid gearing is a special setup of cylindrical gear cutting and grinding machines. A new development, the so-called Hypoloid gearing, addresses the desire of gear manufacturers for more freedoms. Hypoloid gear sets can realize shaft angles between zero and 20° and at the same time, allow a second shaft angle (or an offset) in space that provides the freedom to connect two points in space.
Cubic boron nitride (CBN) finishing of carburized gearing has been shown to have certain economic and geometric advantages and, as a result, it has been applied to a wide variety of precision gears in many different applications. In critical applications such as aerospace drive systems, however, any new process must be carefully evaluated before it is used in a production application. Because of the advantages associated with this process, a test program was instituted to evaluate the load capacity of aerospace-quality gears finished by the CBN process as compared to geometrically identical gears finished by conventional grinding processes. This article presents a brief description of the CBN process, its advantages in an aerospace application, and the results of an extensive test program conducted by Boeing Helicopters (BH) aimed at an evaluation of the effects of this process on the scoring, surface durability, and bending fatigue properties of spur gears. In addition, the results of an x-ray diffraction study to determine the surface and subsurface residual stress distributions of both shot-peened and nonshot-peened CBN-ground gears as compared to similar conventionally ground gears are also presented.
For this interview, we spoke with George Wyss, president, and Dennis Richmond, vice president of Reishauer Corporation about gear grinding and its place in gear manufacturing today.
"A Decade of Performance" is the theme of the American Gear Manufacturers Association Gear Expo 97, to be held October 19-22 at Detroit's Cobo Hall. Products and services related to every aspect of the gear manufacturing process, from turning and grinding the blanks to coating and inspection of the gears,will be represented at the show.
The capabilities and limitations of manufacturing gears by conventional means are well-known and thoroughly documented. In the search to enhance or otherwise improve the gear-making process, manufacturing methods have extended beyond chip-cutting - hobbing, broaching, shaping, shaving, grinding, etc. and their inherent limitations based on cutting selection and speed, feed rates, chip thickness per tooth, cutting pressure, cutter deflection, chatter, surface finish, material hardness, machine rigidity, tooling, setup and other items.
I'm a big believer in the value of IMTS as a marketplace where gear manufacturers can go and look at the latest machine tools and processes; compare hobbing machines, gear grinders and inspection equipment; see turning, milling or grinding machines in action; and ask questions of the various vendors all in one place. This year's IMTS promised to be the biggest ever, and I have no doubt that it will be a valuable experience to those who go there looking for ways to improve the way they manufacture products.
News Items About grinding
1 United Grinding to Display Innovations at GrindTec 2014 (January 27, 2014)
United Grinding, the largest single-source provider of complete and integrated grinding solutions, will showcase its latest grinding, ero... Read News
2 Burka-Kosmos Offers Latest Grinding Wheel (February 3, 2014)
The Mira Ice product line of gear grinding wheels was developed in order to meet the requirements of profile grinding larger gears. A new... Read News
3 Supertec to Present Seven New Grinding Machines at IMTS (June 16, 2010)
Supertec Machinery will exhibit seven new grinding machine models/types at this year's IMTS. They will be located in the Grinding Pav... Read News
4 CIMCOOL 609 Designed for Grinding Performance (June 29, 2011)
CIMCOOL Fluid Technology has created CIMTECH 609, an innovative hybrid developed for superior grinding performance and excellent machinin... Read News
5 Industry Gathers for United Grinding Symposium (June 24, 2014)
The world's largest event in the grinding machine industry drew to a close in Thun (Switzerland) with an enthusiastic audience. Every... Read News
6 Junker Acquires Majority Share in Brazilian Grinding Machine Manufacturer (March 19, 2015)
The Junker Group recently added Brazilian grinding machine manufacturer ZEMA to its corporate group. ZEMA was founded back in 1953, has m... Read News
7 True Gear & Spline Increases Grinding Capacity With New Niles ZP 12 (June 26, 2015)
True Gear& Spline Ltd. recently added CNC gear profile grinding to their machining capabilities with their newly installed Niles ZP 1... Read News
8 Hewland Engineering Expands Grinding Capabilities (May 13, 2015)
Hewland Engineering recently announced a multi-million pound investment in state-of-the-art spiral bevel grinding capability, due to arri... Read News
9 Kapp Offers Advancements in Gear Grinding (April 23, 2012)
Two grinding machines with flexible process capabilities will be on display at booth N-7036 at the IMTS in Chicago, Illinois, September 1... Read News
10 Junker Group Extends Grinding Machine Range with Corundum Line (June 4, 2018)
The Junker Group has extended its range of grinding machines: With its new Zema corundum line, the company is offering efficient solution... Read News
11 Gleason Offers Wobble Compensation in Gear Grinding (December 27, 2012)
Conventional grinding cycles for cylindrical gears typically involve a significant amount of time dedicated to the manual alignment of th... Read News
12 EMAG Offers Hard Turning and Grinding Advantages (March 12, 2013)
The advantages of the process combination hard turning + grinding lie in process stream consolidation, improved component quality and gre... Read News
13 Körber Schleifring Becomes United Grinding (November 12, 2013)
Körber Schleifring, a global provider of grinding machine technology and its North American arm United Grinding Techologies are now ... Read News
14 C&B Machinery Offers Clamp Bore Disc Grinding Machine (November 22, 2013)
C & B Machinery has received multiple orders for its latest generation Model CBV-3 Clamp Bore disc grinding machine. The automotive i... Read News
15 Ultra Grind Offers Two Meter Grinding Capacity (July 31, 2012)
The Hardinge Grinding Group introduces a new 2-meter capacity, UltraGrind 2000 grinding machine manufactured by Jones & Shipman, a Ke... Read News
16 Oelheld Develops HSS Grinding Oil (January 24, 2014)
SintoGrind HSS was especially developed for profile and flute grinding of steel alloys and in particular for High-Speed-Steel and medical... Read News
17 Grinding Wheel Improves Surface Finish (October 29, 2009)
The SK23w ceramic grinding wheel specification from Burka-Kosmos drastically increases the Q'w and V'w rates. This type of grindi... Read News
18 Junker Builds New Platform for Cylindrical and Non-Cylindrical Grinding of Workpieces (June 24, 2015)
Junker recently built a new platform for cylindrical and non-cylindrical grinding of workpieces with a swing diameter of 470 mm and a par... Read News
19 Haas Multigrind CA and CB Machines Utilize High-Capacity Grinding Wheel Shelf Magazines (August 3, 2017)
All Haas Multigrind grinding centers are available with an automatic wheel changer. This feature enables Haas customers to combine ... Read News
20 Röhm KZF-S External Clamping Collet Chucks Designed for Gear Surface Face Grinding (December 7, 2016)
Röhm Products of America now offers a powered external clamping chuck for gear surface face grinding. The KZF-S collet chuck is espe... Read News
21 Junker JUMAT Machine Offers Simultaneous Grinding of ID, OD and Faces of Gears (May 31, 2017)
Junker has introduced the JUMAT 6S 18-20S-18, the latest of Junker's JUMAT series of modular grinding machines, which is capable of g... Read News
22 Service Network and Worcester Polytechnik Launch Grinding Consortium (April 14, 2006)
Service Network is spearheading an effort with Worcester Polytechnic Institute to form a grinding research center located in Worcester, M... Read News
23 Nortons New Gear Grinding Wheels Increase Life of Parallel Axis Spur Gears (April 11, 2006)
The new BRGg VPHS high speed grinding wheels from Saint Gobain are designed to reduce cycle times by increasing metal removal rates. The ... Read News
24 Makinos New Grinding Machining Center Grinds, Drills, Bores and Mills on the Same Machine (January 9, 2007)
Makino introduced the G5 Grinder horizontal machining center, capable of grinding, drilling, boring and milling all on the same machine.... Read News
25 Schafer Gear Adds New Grinding Equipment (May 24, 2007)
Schafer Gear Works invested in new production equipment, including new gear grinding machines in the company's South Bend, IN, and Ro... Read News
26 Sigma Pool Merges All Grinding Activities (February 7, 2005)
Sigma Pool partners have merged all activities in the field of cylindrical gear grinding under the roof of Liebherr-Verzahntechnik GmbH i... Read News
27 Kapp's Rotor Grinding Technology Improves Efficiency by 30 Percent (June 15, 2007)
The Kapp RX 59 allows the rotors used in air compressors to be manufactured on the machines by using a high precision grinding process.Ro... Read News
28 Samputensil Introduces High Capacity Grinding Machine (January 6, 2006)
The new 250G generating grinding machine from Samputensili, introduced at EMO 2005 was developed to achieve a shorter cycle time. Acco... Read News
29 Hewland Installs Klingelnberg Oerlikon G60 Spiral Bevel Gear Grinding Machine (November 16, 2015)
Hewland Engineering recently announce the installation of a Klingelnberg Oerlikon G60 spiral bevel gear grinding machine. Utilizing Kling... Read News
30 United Grinding?s Newest Machine Grinds Shafts and Chucked Workpieces (April 11, 2006)
[photo] The Studen S242 from United Grinding is designed for the hard turning and grinding of high-precision applications for both shaf... Read News
31 Saint-Gobain Introduces Grinding App (August 27, 2012)
Saint-Gobain Abrasives has recently introduced a Norton Abrasives Grinding App. This application includes three calculators includi... Read News
32 New Depressed Center Wheels Introduced by Camel Grinding Wheels (April 6, 2006)
CGW-Camel Grinding Wheels has introduced Fast Cut Series Aluminum Oxide Type 27 Depressed Center Wheels with N-grade bond for right angle... Read News
33 Klingelnberg Opens Blade Grinding Center in Mexico (October 27, 2011)
In August 2011, Klingelnberg's Mexico site was moved to a new facility in Querétaro City. This investment is part of the compa... Read News
34 Gleason Improves Quality for Large Gear Grinding (April 23, 2010)
Gleason's latest generation of Profile Grinding Machines now can be equipped to perform a new process called OPTI-GRIND that signific... Read News
35 Gleason Offers Profile Grinding on Threaded Wheel Gear Grinding Machines (March 27, 2013)
Gleason Corporation recently announced the availability of a Profile Grinding option for its 300TWG Threaded Wheel Grinding Machine... Read News
36 Cinetec Grinding Moves Headquarters to Hagerstown, Maryland (May 29, 2007)
Cinetic Landis Grinding Corp. relocated its headquarters and manufacturing/assembly facility approximately 15 miles to Hagerstown, MD. ... Read News
37 Dapra Offers Grinding and Deburring Tools (October 3, 2011)
Dapra's series of Biax hand-held, air-powered tools include lightweight grinders and variable-speed deburring machines. The SRD 3-55/... Read News
38 Bryant Celebrates 100 Years of Grinding (November 24, 2008)
Bryant Grinder, a division of Vermont Machine Tool Corporation, is celebrating its 100th anniversary in 2009, making it one of the olde... Read News
39 Holroyd Sells Grinding Machines to Chinese Company (December 20, 2011)
U.K.-based Holroyd Machine Tools and Components of Milnrow, Lancashire, a division of the Precision Technologies Group, has announced the... Read News
40 Vomat Filtration Systems Provide 100 Percent Separation of Clean and Dirty Grinding Oil (December 20, 2017)
To manufacture precision tools, tool manufacturers must optimally coordinate all parameters involved in the process such as edge preparat... Read News
41 Elliot Tool Technology Carbide-Roll Burnishing Tools Designed to Eliminate Grinding, Honing and Polishing Processes (May 11, 2016)
Carbide-Roll Burnishing Tools by Elliott Tool Technology, which produce a mirror-like surface finish while eliminating secondary operatio... Read News
42 Saint-Gobain Norton Quantum3 Depressed Center Grinding Wheels Designed to Decrease Downtime, Improve User Comfort (March 29, 2016)
Saint-Gobain Abrasives has introduced Norton Quantum3 (NQ3) Depressed Center Grinding Wheels. Featuring a proprietary grain along with a ... Read News
43 Samputensili SG 160 Sky Grind Introduces Dry Grinding of Gears to Star SU Line (December 24, 2015)
Samputensili has recently launched a world premiere at EMO Milan 2015. The new machine, the SG 160 Sky Grind, is designed to eliminate th... Read News
44 Klingelnberg to Showcase Oerlikon G 30 Bevel Gear Grinding Machine at Gear Expo (September 9, 2015)
Klingelnberg will be exhibiting its capabilities with a presentation of cutting-edge technology “made in Germany” in the form... Read News
45 Chevalier Grinder Features Rough and Fine-Grinding Cycles (February 3, 2017)
The FSG-1224ADIII is fully automatic on the X- and Y-axis, includes 2-axis servo control and a new PLC controller that features a grind c... Read News
46 EMAG VLC 100 GT Combines Vertical Turning and Finish Grinding in One Package (March 31, 2017)
When it comes to machining times, combining various machining processes in one setup offers enormous savings potential. With the combinat... Read News
47 Gleason 410SCG Shaving Cutter Grinding Machine Speeds Up Shaving Cutter Re-Sharpening (November 8, 2017)
Gleason is meeting the global need for fast, high quality re-sharpening of shaving cutters up to 400 mm in diameter and Module 14 with th... Read News
48 DVS Technology Group Presenting Gear Grinding Solutions at EMO (September 20, 2017)
The EMO fair booth of DVS Technology Group in Hall 17, Booth C46 will be focusing on the high-precision machining of components for power... Read News
49 Meister Abrasives HPL Grinding Wheels Naturally Release Lubricant as they Grind (August 17, 2017)
Meister Abrasives new HPL (High Performance Lubrication) Grinding Wheels rely on premium grade CBN crystals fixed with durable, porous, i... Read News
50 ANCA Motion LinX Linear Motor Technology Now Equipped on Grinding Machines for Improved Chip Evacuation (May 18, 2017)
Highly polished flutes and gash surfaces improve chip evacuation and aid tool performance. The smoother surface enables swarf (or chips) ... Read News
51 Gleason Genesis 200GX Threaded Wheel Grinding Machine to be Introduced at Gear Expo (August 5, 2015)
Gleason recently announced it will introduce advanced machines, tooling, and global customer support services covering a wide array of pr... Read News
52 Junker and Zema to Exhibit Gear Grinding Machines Together at EMO Milano (July 30, 2015)
At EMO Milano 2015, Junker Group and Zema will be exhibiting together for the first time in Europe: Zema will be demonstrating a cylindri... Read News
53 PTG to Showcase Grinding in Germany (February 12, 2014)
PTG Deutschland GmbH, the German-based division of Britain’s Precision Technologies Group, has chosen GrindTec 2014 to showcase its... Read News
54 Forest City Gear Expands Small Diameter ID/OD Grinding Capability (December 13, 2017)
Forest City Gear has expanded its capabilities for the hard finishing of smaller diameter gears with particularly tight ID and length tol... Read News
55 3M Introduces Cubitron II Conventional Wheels for Gear Grinding (November 1, 2013)
3M Abrasive Systems is introducing 3M Cubitron II Conventional Wheels for Gear Grinding, giving engineers new tools to take the manufactu... Read News
56 Norton Grinding Abrasives Feature Bond Technology (June 20, 2013)
Norton Abrasives, a brand of Saint-Gobain, has developed and launched Norton Vitrium3, the next generation of bonded abrasives prod... Read News
57 United Grinding Invites Customers to Grinding Symposium (March 5, 2014)
The United Grinding Group – Körber Schleifring up until EMO 2013 – has clearly understood the signs of the times in the ... Read News
58 United Grinding Announces New President (March 27, 2014)
United Grinding North America, Inc. recently announced that current president and CEO, Rodger Pinney, has been elected as vice chairman... Read News
59 Junker Delivers 500th Grinding Machine to Volkswagen Group (June 10, 2015)
Grinding machine manufacturer Junker recently celebrated a milestone as the Volkswagen Group recently purchased their 500th Junker grindi... Read News
60 DiaGrind 535-5 Offers Advantages in Gear Honing and Grinding (June 11, 2014)
The multifunctional metalworking fluid DiaGrind 535-5 has many enthusiastic users all over the world. They range from small shops to mult... Read News
61 Vomat Offers Temp Stability During Grinding (May 23, 2014)
In order to produce high-performance cutting tools, tool manufacturers go to great lengths to get all manufacturing parameters right. Production conditions have tremendous influence on the final quality of the tool... Read News
62 EMAG Introduces Small Grinding Center (April 15, 2014)
Demand for components such as gearwheels, planetary gears, chain gears or flanged components for cars typically runs in quantities of millions... Read News
63 Holroyd Launches Worm Gear Grinding Stations (May 31, 2013)
Holroyd Precision Limited has launched a brand new, full CNC machine range that is specifically designed to provide ultra-high levels of ... Read News