Yaw and Pitch Rolling Bearing Design Types

Modern wind turbines use large slewing rings at the root of each blade to enable pitch angle changes and thus aerodynamic performance and load control. Yaw bearings are used for angular realignment of the nacelle into the predominant wind direction. These applications require long periods in nearly stationary positions with large stochastic loads. Due to this demanding load environment and the fact that bearings exist in the critical load path, their design becomes critical to the safety and reliability of most turbine designs.
Large wind turbines (those rated at more than 250 kW) use ball or roller bearings with special configurations for blade retention pitch bearing and yaw bearing locations. The bearings consist of two ring-rolled forgings forming the outer and inner raceways and a complement of either balls or rollers. The inner and outer continuous-ring forgings have mounting holes that allow the bearing to be bolted directly to the supporting structures. The balls or rollers are inserted into the bearing through a radial cylindrical hole in one of the rings. The hole then is closed using a removable loading plug con-toured to the ball path or roller path surface. 
It is common practice to cut a spur gear integral with one of the bearing rings, especially for the yaw bearing application. Individual plastic spacers or thin section cage arc segments are used to separate the balls. The spacers are cylindrical with a hemispherical end. The individual rollers in the cross-roller bearing are separated by plastic, saddle-shaped spacers. The rollers in the cross-roller bearing alternate in their orientation to carry load.
The inner and outer rings are hardened from 250 to 300 Brinell hardness (HB). This is referred to as the “core hardness” of the ring. This core hardness should provide adequate core yield and fatigue strength, yet remain at a hardness low enough to facilitate machining of the rings, gear teeth, and mounting-bolt holes. The actual ball or roller path (rolling contact surface) is induction heated, quenched, and tempered to provide a hard surface or “case.” The surface hardness of the raceway is a minimum of 58 HRC (Rockwell C scale hardness). The depth of the hardened case is defined as the depth to a hardness of 50 HRC.
The two-row, eight-point contact ball bearing type is more costly to manufacture than the single-row, four-point contact ball bearing. In addition to having a second row of balls and separators, the two-row bearing must be repeatedly assembled and disassembled during manufacture to accurately measure and match the internal diametral clearance or preload of the two ball rows.
The main advantages of the eight-point contact ball bearing, as compared to the four-point contact ball bearing, are:
• Lower ball loads;
• Lower Hertz stresses;
• Less required case depth; and
• Increased fatigue life.

UWE have self-develpoed hub for slewing ring testing

To make UWE slewing ring can work in perfect performance, we have self-developed hub to test slewing rings. We test every slewing ring before packaging, this could inspect if bearing could work with gear well, ball and spacer working performance,mounting hole precision and the torque changes..
For wind power, UWE keeps designing and developing.

Electricity from wind

Germany, the US, Spain, Denmark, India and Australia are among the world's leading nations in the acquisition of wind energy. Wind generated energy is growing in leaps and bounds.

Wind power is now the world's fastest growing energy source and has also become one of the most rapidly expanding industries, with sales of roughly $3 billion in 2008. Major offshore developments are likely in northern European waters in the early part of the next century.

This will be the next major step for this technology and will result in a dramatic increase in decentralized electricity generation. Offshore wind has the potential to deliver substantial quantities of energy at a price that is cheaper than most of the other renewable energies, as wind speeds are generally higher offshore than on land

As of 1999, global wind energy capacity topped 10,000 megawatts, which is approximately 16 billion kilowatt-hours of electricity. That's enough to serve over 5 cities the size of Miami , according to the American Wind Energy Association. Five Miamis may not seem significant, but if we make the predicted strides in the near future, wind power could be one of our main sources of electricity. "With today's technology, wind energy could provide 20% of America 's electricity (or about the amount nuclear power provides) with turbines installed on less than 1% of its land area. And within that area, less than 5% of the land would be occupied by wind equipment the remaining 95% could continue to be used for farming or ranching." By the year 2010, 10 million average American homes may be supplied by wind power, preventing 100 million metric tons of CO 2 emissions every year.

Mexico customer visited UWE

Today, Mexico customer Miguel visited UWE bearings.He visited UWE slewing bearing workshop and physico-chemical room. He showed great satisfication with UWE including slewing bearing technology,machining condition,working environment,process machines. We talked and discussed more about the slewing bearing used for wind turbines,water treatment,mining and machinery. 
This visit will help us to expend UWE slewing ring business to Mexico, and will help UWE to make own brand famous.

Slewing Ring Bearing Overhauling

Revolving inspection is necessary to check correct installation after the slewing ring is intalled. For small size machinery, we can  revolve the slewing bearing by hand, to ensure whether can run smoothly. Inspection items include revolving not smoothly due to foreign objects, bruises and indentation; moment force unstable due to unproper installation and unproper processing of support; over moment force due to backlash too small, installation error and sealing friction. If there is no abnormal status, dynamic run of the slewing bearing can be proceeded.

UWE slewing ring for excavators

UWE excavator slewing bearings/slewing rings have a high load carrying capacity, a versatile range of applications and are highly cost-effective. Due to their design, a single bearing can reliably support radial, axial and tilting moment loads. It is therefore possible in many cases to replace bearing arrangements comprising a combination of radial and axial bearings by a single bearing.

This reduces, in some cases considerably, the costs and work required in the design of the adjacent construction and the fitting of bearings. It is made up of mounting holes, inner gear or outer gear, grease hole and sealing device. It has many positive characteristics; compact structure, light weight, good rigidity, steady speed and high precision.

UWE can offer a wide range of  excavators, like  Komatsu, Hitachi, Kobelco, Caterpillar, Hyundai and so on. Small size four-point contact ball slewing bearings often used for this application.Single row four point contact bll bearing is composed of two seatings. This type slewing bearing ring/slewing bearing/slewing ring features compact in design,light in weight, the balls contact with the circular raceway at four moment may be simultaneously. 

UWE bearing-"one hundred days no accident"

In order to continue to pursue and achieve high quality slewing ring objectives, raise the quality and safety awareness of employees, enhance cohesion and competitiveness in the market, the company  has held a working sessions about “ one hundred days no accident” in our conference hall. UWE president  Wang Jianjun, and relevant department heads, and other shop workers attended the meeting.
Conference topic was "improving the quality awareness, improve quality standards to ensure safe production, improve safety awareness, and promote sound and rapid development". The meeting pointed that the aim is to improve the quality and ensure safety in production and increasing the training of staff, and strengthen the assessment about production discipline supervision, implementation of safe production and strengthen production safety management.
Advantage of the activities to enhance employee safety awareness, constantly improve production quality in the case of safe production, promote the prosperity and development for the company.

"UWE"-famous trademark in Liaoning

UWE bearing has won the honorary title of  Dalian famous brand in 2010, and was identified as the national high-tech enterprise in 2011. Company attaches great importance to create famous brand, and trying our best to build UWE image. At present, the company is to implement the brand strategy, identified as "Famous brand in Liaoning Province" by the Liaoning Provincial Administration for Industry.
UWE bearing has an industry leading experts and a large number of outstanding engineering and technical personnel, all of them have been committed to reach and develop slewing bearing ,11 R & D projects obtained national patent..
UWE will continue to focus on customer’s demand, and constantly research and innovation to achieve the development concept “Technology support UWE, Quality achieve eternity”.For the creation of Chinese power bearing country, to achieve Industrial prosperous, revitalize national industry and create brilliant tomorrow.

Slewing Ring Work and Utility

Slewing ring is a revolving bearing with gear rings drove by a motor. UWE slewing ring usually is utilized in heavy machines that slowly revolves on a horizontal platform. Typically the slewing ring was used in solar energy tracking system, cranewind power generator, hoisting system etc.. For the highly precision slewing bearing, it can also used in construction machinery.
Types of the slewing bearing are usually into three modes: without gear, internal gear and external gear.

Slewing Ring Cleaning and Assembling

After the slewing ring is assembled, elements of each suit and each line cannot be exchanged. When disassemble the slewing ring for cleaning, it should be operated based on the slewing bearing assembling drawing strictly, the half ring of upper and lower should be assembled according to the original drilling hole position.

Gear surface of the slewing bearing should be cleaned every 10 days to remove sundries, and sprayed with the lubricating grease.


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