Bearing Manufacturer Unveils Plans for U.S. Wind Energy R&D Center

Chinese OEM and U.S. bearing manufacturer team up for turbines

The Timken Company and Xinjiang Goldwind Science & Technology Co., Ltd. have signed a memorandum of long-term strategic collaboration in the United States to cooperate on a range of technical services, products, and aftermarket support for the development, supply and maintenance of advanced wind-turbine components.

The memorandum’s three-year term extends and broadens an existing relationship between the two companies, with opportunity to multiply significantly their current collaboration. To support these efforts, Timken will develop additional capacity in China and at its other facilities focused on wind energy technology to support Goldwind’s expansion globally.

The memorandum reflects the highest level of collaboration between the companies, including the following Timken capabilities:

• Original-equipment design and engineering services;
• Testing at Timken’s new Wind Energy Research and Development Center scheduled to open in 2012
• Supply of bearings and adjacent power-transmission components
• Optimization of wind-turbine installations
• Field services and aftermarket lifecycle support for Goldwind’s growing installed base, including on-line intelligence monitoring systems, and
• Integrated supply-chain management and wind-farm sustainability services.

Goldwind and Timken executives said the memorandum reinforces their commitment to develop sustainable wind energy projects to strengthen the global balance of green power generation. The companies began collaboration on 1.5 MW wind turbines. In 2010, they signed an agreement valued at $26 million supporting development of additional, multi-megawatt projects.

Goldwind
www.Goldwindamerica.com

Timken Co.
http://www.timken.com/

Special polyurethane improves abrasion resistance

The Timken UltraWind P1 Seal is a significant wind-turbine bearing seal with a polyurethane design that provides increased resistance to abrasion for longer wind-turbine service life and more reliable performance than most other commonly used sealing materials. “Seals have an integral role in maximizing wind-turbine uptime and productivity because they prevent lubrication leakage and bearing contamination,” said Hans Landin, director of Process Industries original equipment and wind energy at Timken. “However, over time the cumulative impact of abrasive forces caused by varying loads and speeds, as well as extreme temperature fluctuations, rain, snow, debris, and lubrication challenges, can significantly reduce seal performance in wind-turbines. The new UltraWind P1 Seal addresses the problem with the latest polyurethane technology.”

In addition to its durable polyurethane base, the Timken UltraWind P1 Seal contains a variety of other features, including:

• A flexible sealing lip that handles misalignment or run-out in the application of the bearing. The lip’s special profile also helps minimize heat generation and cone wear while helping to accommodate bearing deflections.
• A corrosion-resistant, stainless steel garter spring that helps prevent rust.
• A machined design for a broader, more diverse range of applications, plus ease of installation via stress minimization. This design also allows for multiple positions at the cone lip OD contact; and

The Timken Company
www.timken.com

How to automate bearing lubrication

Due to long, continuous operations, wind turbine main-shaft bearings need consistent, reliable lubrication. Timken’s Wind Energy Lubrication System addresses such needs with a single pump, in two models capable of working with either series-progressive or injector-based lubricant delivery methods. Timken says the HP pump model provides continuous lubrication with a conventional method of pressure purging old grease. An LP version uses an active-purge system that removes old grease without internal bearing-cavity pressure.

Timken says a rugged and versatile pump is at the heart of both units. They feature powerful pump performance for consistent delivery of grease up to NLGI No. 2 and excellent “cold climate” pumping properties. An offset piston element reduces side loading, while increasing pump life from a standard 24 Vdc power connection (115/230 Vac is optional). CPC and DIN style power-connection are options. An 8-liter standard grease reservoir allows once-yearly turbine maintenance with stirring paddle and wiper to minimize air pockets and grease separation.

Three fill ports simplify lubricant refilling when mounted in tight areas. Advanced flow elements reduce stagnant grease flow to the pump inlet. In a conventional method of grease movement, fresh grease is pushed into the cavity. It finds a path of least resistance around accumulations of old grease. This allows inadequate replenishment of grease in one of the bearing rows.

An active purge system removes old grease mechanically and by suction at the exit side of each bearing row for freer grease movement. Minimal amounts of fresh grease are directed to each row, providing positive replenishment and assuring that neither row is starved for lubrication.

The lubrication units also sport a clever and patented charger, which mechanically charges old grease into an orifice where it can be removed by suction. The ability to remove grease without cavity pressure improves seal function because it provides optimum lubrication.

Knowing how much and how often lubricant can be introduced to critical bearing contact areas is a primary challenge to obtaining proper lubrication of any bearing. Common practice in a two-row bearing is to provide a single grease-injection inlet between the two bearing rows. Over time, this can cause uneven lubrication in each row due to aged grease accumulating near the inlet. Accumulation then forces fresh grease to a path of least resistance, potentially starving grease to one of the bearing rows. The LP lubricator addresses the issue with a low-pressure centralized-lubrication system that directs grease to inlets and uses an active purging method to reliably lubricate bearings. The system’s central pump delivers lubricant through a supply line to multiple banks of injectors. When used with tapered roller bearings, each injector bank operates independently to lubricate each bearing row at the small end of the roller. Lubricant naturally pumps to the large-roller end where the grease is then “charged” into outlet ports and suction elements powered by the grease pump, which pull old grease to a waste container.

Timken Co.

www.timken.com

Wear-resistant bearings for wind equipment

High on the list of O&M crews are ways to extend bearing life and reducing wear. To handle the challenge, Timken engineers developed a bearing that reduce life-limiting wear problems that trouble main shaft and gearbox bearings. Common wear problems include micropitting on main shafts, spherical-roller bearings and micropitting, smearing and brittle flaking for wind-turbine-gearbox bearings.

Wear that limits the life of main shaft spherical-roller bearings is not classical rolling contact fatigue, but mostly micropitting wear. It is caused by interaction of the raceway and roller asperities, leading to high stresses in the contact. The normal stress alone is not typically sufficient to cause initiate a crack at or near the surface early in a bearing’s life cycle. However, the addition of frictional shear stress increases the bulk contact stress values and brings the maximum values closer to the surface, allowing these localized stresses under the asperity contacts to become significant. This type of interaction typically occurs when the lubricant film is insufficiently thick to separate the contacts and when there is relative sliding between the two contacting surfaces. It is termed low-cycle micropitting.

A team at the bearing company performed an analysis of typical radial and thrust forces on a 230/600 main shaft spherical roller bearing along with the radial clearances inherent in the bearing design. Results indicate that the entire load is supported by the downwind row of the bearing leaving the upwind row essentially unloaded. This uneven load distribution results in higher loads on the downwind row, as well as a full 360° loaded arc of rollers. The fully loaded arc of rollers increases the number of stress cycles occurring on a point on the inner raceway for every shaft revolution.

Main shaft bearings typically rotate at 10 to 20 rpm, not enough to generate a substantial lubricant film thickness even with higher viscosity lubricants. Consequently, higher loads, more stress cycles, and thinner lubricant films are present on the downwind roll increasing the risk of micropitting, especially when roller/raceway sliding is present.

Wear-resistant bearings provide up to 3.5 times greater L10 life for main shaft and gearbox bearings. The company says benefits of the new bearing include resistance to:

• Smearing, scuffing, and false brinelling damage
• Life reduction from debris damage
• Low cycle micropitting

Timken says the bearings reduce micropitting, smearing, and brittle flaking often seen in competitors’ original equipment bearings for main shaft and gearbox applications. The company also provides support services for O&M crews.

Timken Co.
www.timken.com

Wind bearing includes seals, lube, and monitoring

UltraWind bearings provide a tapered roller bearings with integrated seals, lubrication, and condition monitoring. With the highest life ratings in the industry certified by Germanischer Lloyd, the UltraWind Series provides a cost-conscious, simplified drivetrain for main-shaft wind turbine designs (gear and gearless). For multi-megawatt turbines, the pre-loaded tapered roller bearing is better suited than others to address concerns such as stresses, rigidity, and load management that affect bearing life and reliability. The UltraWind series provides superior stiffness to manage motion of the main shaft and rotor. Its bearing raceway profiles control maximum stress levels for enhanced durability, and the cage is optimized for capacity and roller retention, including both steel and polymer configurations. Hence, the bearings are part of an integrated main-shaft for specific operating requirements. In collaboration with customers, manufacturer Timken takes into account the total operation of the bearing and power-drive system to optimize the sustainable life of the equipment.

Timken Co.

timken.com

Timken wins $26 million wind-energy contract

The Timken Company says it has received a contract worth $26 million to supply wind turbine products and services to China’s Xinjiang Goldwind Science & Technology Company.

The contract will support more than 1,500 MW of new wind power capacity. Timken will contribute to Goldwind’s expansion in the industry, with Timken providing engineering support, advanced bearings that include its new UltraWind tapered roller bearings, and condition-monitoring systems and services for Goldwind’s current 1.5-MW and 2.5-MW platforms. The companies also will collaborate on future wind-turbine developments.

In 2009, Goldwind received new wind-power-capacity orders of about 2,722 MW, accounting for nearly 20% of wind generated power added in China last year. The company will purchase bearings and gearbox systems for its multi-MW wind turbines. The company’s purchase includes seals, lubrication, and online condition monitoring and support services for the life of the equipment.

Christopher Coughlin, President of Timken Process Industries says the companies have agreed to collaborate further on development programs, including using Timken’s advanced engineering design to reduce cycle times for new platforms and incorporating the company’s “life cycle” service approach to contribute to sustainable performance and uptime of Goldwind’s projects around the world.

Timken supplies a range of wind-power products for the global market including: engineering design, development and testing support; alloy steels; gearbox components and systems; tapered, cylindrical, and spherical roller bearings; seals and lubrication products; online condition-monitoring; and global field services and technical support.

The company recently began producing large bore bearings for wind turbines in Xiangtan, Hunan Province, and retooled and expanded its U.S. facilities in Asheboro, N.C. and Tyger River, S.C. to serve customers in the industry.

Bearing and steel manufacturer unveils many new products

By making investments during the recession to expand its wind power offering and capacity domestically and internationally, The Timken Company, in Booth 2803, has introduced what it says is a record number of new product developments for the industry.

For example, the manufacturer of proprietary alloy steel and power transmission components and systems, has expanded facilities in Asheboro, N.C.; Tyger River, S.C.; and a new plant in Xiangtan, China, all to produce clean-steel from facilities in Canton, Ohio and wind bearing production in Wuxi, China; Chennai, India; and Ploesti, Romania. Working with the leading wind-turbine manufacturers at varying stages of development, the company has established a supply chain around the world.

Among technology innovations Timken is showcasing at the 2010 Wind Energy Conference and Exhibition in Dallas May 22-26, Booth 2803, are:

• New Timken Wear-Resistant cylindrical and spherical bearings. This bearing technology extends operating life up to three times longer than standard cylindrical or spherical bearings, says Timken. With up to 15% less torque, the wear-resistant bearings resist  damages such as smearing, scuffing, false brinelling and micropitting (technical paper available from Timken). 
• The new UltraWind Tapered Roller Bearing from Timken has the highest life ratings in the industry, as certified by Germanischer Lloyd. This main-shaft, ultra large-bore bearing has a simplified drivetrain design that saves capital-equipment costs.
• Timken’s new Wind Energy Lubrication System enhances optimal wind power production by precisely and evenly directing fresh grease to bearing inlets while actively purging old lubricant with a, centralized-lubrication delivery device that works with either series-progressive or injector-based lubricant delivery methods.
• Three new Wind Seals include the Eco Turn Labyrinth, a non-contacting design that prevents against grease migration and contaminants, ideally suited for Timken’s low-pressure lubrication system. The Elastomer Wind Seal is engineered with a flexible sealing lip to handle bearing deflections and minimize friction and cone wear; while the PTFE Wind Energy Seal offers excellent chemical inertness and low friction to help maximize performance (see product information);
• A new Middle Frequency Induction Heater provides a simple and safe approach to assembly and disassembly of large wind (see product information);
• The Planet Pac and Integrated Flexpin Bearings provide power dense solutions to increase performance and reliability of gearboxes
• The company’s Clean Steel provides superior strength and durable performance for bearings and gears
• An Online Intelligence System offers a unique condition-monitoring system designed specifically to improve uptime for low-speed powertrains.
  Timken’s proprietary Syber Advanced Wind System Analysis is an engineering platform that reduces development time and costs while optimizing main shaft and gearbox systems for sustainable performance.

Clever Bearing and Planetary Drive Carries Greater Load

Uncontrollable and highly variable wind forces adversely affect the performance and reliability of planetary gears inside wind-turbine power transmissions. A couple developments from The Timken Co., Canton, Ohio, can lower maintenance on rolling elements and carry greater load in a planetary gearset. In the first, the Integrated Flexpin Bearing (IFB) equalizes gear loads, reduces internal stresses and significantly extends wind turbine reliability. One wind turbine gearbox in Scotland’s Orkney Islands, for instance, uses IFB units and has been operating for four years. The company says it has demonstrated a more than fourfold increase in the accumulated service life compared to what previous designs could deliver. “The condition of the gears and bearings is like the day they were installed,” says Timken chief technologist Gerald Fox. The IFB can be used in open planetary gear sets and consists of a double-cantilevered pin supporting the bearing and gear. The cantilevered pin attaches to a single carrier wall, and a cantilevered sleeve mounts to the free end of the pin. Gears and bearings mount on the sleeve.

The integrated bearing and gear construction is simplified to provide more space for bearing rolling elements to maximize the power rating of the bearing system. For max durability, coatings may be applied to the rolling and sliding surfaces, making this design the most power dense in the industry, according to the company. The result: More evenly distributed torque among multiple planet gears and longer gear and bearing life. In addition, combining shafts, bearings, and gears in one unit, the design also cuts weight and lowers cost. When compared with an equivalent sized, conventional open planetary gear system, the highly engineered IFB can transfer greater power and maintain its reliability. “This solution creates new and substantial opportunities for wind-energy machine designers to either downsize systems or upgrade the rated horsepower of their existing machinery,” says Fox.

The company has developed the technology so it can also work in closed-carrier planetary drive systems. Using two opposing arrays of IFBs mounted on a double-wall planetary carrier, there is potential to increase the torque density available today in this type of drive by as much as 50%. This patented innovation, called Integrated Flex Drive, lets a closed-carrier system gear-box designer reduce the size and mass atop turbine towers, one way to create higher-capacity, lighter-weight wind turbines. “In addition to increasing torque density, these systems can reduce gear loads and reduce the need for gear profile and lead correction. These improvements can reduce the costs of generating electricity from wind,” adds Fox.