Bearing is the important support of mechanical transmission mechanism, directly affecting the technical level and quality performance of equipment, known as the ‘joints of industry’. At present, wind turbine bearings, high-speed rail bearings and other high-end bearings are monopoly and control by foreign companies, high-end bearings have become an important strategic resource, is an important material for national defence and security, livelihood protection. Domestic bearing enterprise product research and development capabilities and foreign advanced enterprises compared with a large gap, especially in the bearing comprehensive performance testing, inspection and testing, product development, engineering and technical services, the gap is even greater, these gaps have become a constraint on the domestic bearing product innovation and upgrading and technological progress of the bottleneck. Bearing enterprises to strengthen the means of trial production of new products, comprehensively enhance the bearing test capacity, improve the bearing comprehensive inspection and testing methods, can enhance the independent research and development and innovation ability, enhance the enterprise's ability to compete in the market.

With the high-speed, high-precision, high reliability, low friction, low vibration, low noise bearings and special working conditions under the use of special bearing products continue to research and development, bearing testing technology, testing and other aspects of the higher requirements have been put forward, but also for the vigorous development of bearing test equipment provides a broad market and opportunities. At present, China Machine Testing has provided all kinds of bearing test equipment for many industries including aviation, aerospace, rail transport, research institutes and colleges and universities, including fatigue life test equipment for joint bearings, rolling bearings, wheel bearings of automobiles and trains, landing gear bearings of aircrafts, main rotor bearings of helicopters and so on.

There are many types of bearing test machines with different functions and uses, including bearing performance test machine, fatigue life test machine, strengthening test machine, design verification test machine, etc. However, the main machine structure principle, load application technology, driving technology, testing technology and control technology of these test machines are basically the same. The following is a detailed introduction to the common technologies of the bearing testing machine.

2 Host structure principle

The main frame of the test machine is mainly used for bearing and bearing special tooling connection, measurement and control parts of the installation layout. The special fixtures include the bearing spindle, test bearings and bearing lubrication seals, etc. Among them, the test bearings are the most important parts of the machine. Among them, the accompanying test bearing is a key component of the testing machine, and its performance determines the ultimate rotational speed and large bearing capacity of the testing machine, and also determines the rotational accuracy of the testing machine, which in turn affects the spindle runout and the accuracy of the test data. According to the host structure classification, generally divided into bridge structure, cantilever structure, combined structure.

2.1 Bridge structure

Bridge structure is divided into three-point structure and four-point structure. In the three-point structure, there is a test bearing in the middle, and two accompanying test bearings are installed at both ends to play a supporting role. In the four-point structure, there are two test bearings in the middle and two accompanying test bearings at both ends for support. Among them, the accompanying test bearings can also adopt the same specification test bearings, and four bearings can be tested at the same time. The bridge structure testing machine is mostly used for fatigue life test.

2.2 Cantilever structure

The test bearing mounting shaft adopts cantilever beam structure, with one side supporting and one side mounting the test bearing, and only one set of bearings can be tested at a time, which is convenient for disassembling and testing, and it is easy to expand the functions, such as increasing the high and low temperatures, water spraying and powder spraying environments, and mud environments. The cantilever structure testing machine is mostly used for performance test and research.

2.3 Combined structure

The use of similar test bearings under the conditions of the installation structure, or directly using the test bearings when the use of the axle box and spindle structure of the host. This structure is complex, but the test method is closer to the actual working conditions, the application of the bearing is more instructive, mainly used for simulation of the working conditions of the test machine.

3 load application technology

Test load is a key indicator of the bearing test machine, its load size determines the size range of the test bearing, its loading accuracy determines the accuracy of the test results.

Different functional requirements of the bearing test machine on the accuracy and speed requirements are different, such as bearing strengthening test machine on the loading accuracy requirements are high, generally need to reach 0.5% FS, but the loading speed requirements of slow loading can be. Commonly used methods of load application are lever weight loading, spring loading, electric loading, hydraulic loading and so on.