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May/June 1998

Archive > 1998 > May/June 1998

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Feature Articles

New Guidelines For Wind Turbine Gearboxes
The wind turbine industry has been plagued with gearbox failures, which cause repair costs, legal expenses, lost energy production and environmental pollution.

AGMA and ISO Accuracy Standards
The American Gear Manufacturers Association (AGMA) is accredited by the American National Standards Institute (ANSI) to write all U.S. standards on gearing. However, in response to the growing interest in a global marketplace, AGMA became involved with the International Standards Organization (ISO) several years ago, first as an observer in the late 1970s and then as a participant, starting in the early 1980s. In 1993, AGMA became Secretariat (or administrator) for Technical Committee 60 of ISO, which administers ISO gear standards development.

Dry Cutting of Bevel and Hypoid Gears
High-speed machining using carbide has been used for some decades for milling and turning operations. The intermittent character of the gear cutting process has delayed the use of carbide tools in gear manufacturing. Carbide was found at first to be too brittle for interrupted cutting actions. In the meantime, however, a number of different carbide grades were developed. The first successful studies in carbide hobbing of cylindrical gears were completed during the mid-80s, but still did not lead to a breakthrough in the use of carbide cutting tools for gear production. Since the carbide was quite expensive and the tool life was too short, a TiN-coated, high-speed steel hob was more economical than an uncoated carbide hob.

Technical Articles

Hard Gear Finishing With CBN-Basic Considerations
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.

Hobs & Form Relived Cutters: Common Sharpening Problems
Fig. 1 shows the effects of positive and negative rake on finished gear teeth. Incorrect positive rake (A) increase the depth and decreases the pressure angle on the hob tooth. The resulting gear tooth is thick at the top and thin at the bottom. Incorrect negative rake (B) decreases the depth and increases the pressure angle. This results in a cutting drag and makes the gear tooth thin at the top and thick at the bottom.

Relationship Between Wear and Pitting Phenomena in Worm Gears
Worm gears display unique behavior of surfaces because of the presence of wear phenomena in addition to contact pressure phenomena.

Departments

Meeting The Challenge (Publishers Page)
Every once in a while something happens to fundamentally change the nature of your business. Despite the best of intentions and the most careful planning, there's no way we can anticipate every event. What do you do, for example, when your two biggest competitors merge, when the economy collapses in the region that imports your products or when key employees leave your company? Your reactions may make the difference between success and struggling to survive.

Product News (Product News)
Welcome to our Product News page. Here we feature new products of interest to the gear and gear products markets.

Technical Calendar (Events)
Complete Technical Calendar for March/April 1998.

Industry News (Industry News)
Industry News for May/June 1998.

Thoughts For Gear Technologists (Addendum)
Every now and then, it strikes us as wise to keep our thoughts to ourselves and let our betters speak for us. Therefore, we present to you a collection of observations on work; science and other items of interest to gear engineers.