Abstract: This article introduces the main structure, loading system, and monitoring system of the ABLT-7 bearing life and reliability strengthening testing machine. The test shows that it can meet the life and reliability enhancement test of the Bearing Unit, and can also perform the limit speed and leakage temperature rise test.

Keywords: Bearing Unit; life; Testing machine; reliability

In the "Eleventh Five Year Plan" for the development of China's bearing industry, one of the key points is to carry out technical research and development to improve the service life and reliability of rolling bearings. To this end, the ABLT series bearing service life and reliability strengthening testing machine has been developed and two Chinese invention patents have been authorized. This article provides a detailed introduction to the ABLT-7 type Bearing Unit life and reliability strengthening testing machine.

1. Main technical parameters

Based on the actual operating conditions of the Bearing Unit, the testing machine is designed according to the following parameters. The inner diameter of the test bearing is 20-60 mm; The number of test bearings is 4 sets; The test bearing speed is 500-5000 r/m in (variable frequency speed regulation); The maximum radial load of the test bearing is 25 kN; The measurement and control method is computer automatic monitoring, automatic alarm shutdown, and automatic recording; The measurement parameters include bearing speed, temperature, and vibration.

2. Main structure and characteristics

The ABLT-7 testing machine can simultaneously test 4 sets of bearings (2 sets in the middle and 2 sets at both ends). The bearing unit is equipped with vibration sensors and temperature sensors. During the testing process, the vibration and temperature changes of the 4 sets of bearings can be measured separately. The main structure of the testing machine is shown in Figure 1. Two radial loading cylinders are installed below the two intermediate pads to apply radial loads to the test bearings. The test bearing speed is achieved by a frequency converter, an electric motor, a multi wedge belt, a transmission shaft, a coupling, a connecting shaft (small square shaft), and a test shaft.

The bearing unit is generally formed by casting or stamping, with large dimensional variability. The traditional single cylinder loading method is prone to biased loading; Therefore, this machine adopts dual oil cylinder loading, which can effectively compensate for the biased load caused by dimensional errors and ensure that each set of bearings is uniformly loaded.

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1- Test axis; 2- Nut; 3- Test bearings; 4- Medium cushion plate; 5- Vibration sensor; 6- End pad; 7- Temperature sensor; 8- Coupling; 9- Transmission device; 10- Electric motor; 11- Hydraulic cylinder

Figure 1 Main structure of ABLT-7 testing machine

2.1 Transmission System

The electric motor and the drive shaft are driven by a multi wedge belt, using a frequency converter for speed regulation, and the speed sensor is located next to the drive shaft pulley. The synchronous speed of the electric motor is 1500 r/min. There are two transmission ratios between the electric motor and the drive shaft (i=2 or i=1/2). When the required speed n ≤ 1500 r/m in, install the large pulley on the drive shaft and the small pulley on the motor shaft, with a transmission ratio of i=1/2. When n ≥ 1500 r/m in, the small pulley is mounted on the drive shaft and the large pulley is mounted on the motor shaft, with a transmission ratio of i=2.

2.2 Loading System

The loading system principle of ABLT-7 testing machine is shown in Figure 2. The pressure oil is provided by the hydraulic pump station, and the pressure regulating valve adjusts the secondary pressure oil pressure of the valve based on the weight of the weight. The maximum allowable pressure of the secondary pressure oil is 13 MPa. Accumulators can stabilize pressure and reduce pressure fluctuations caused by leaks. CT1 is a two position four-way reversing valve, which is in position A when entering oil and in position B when exiting oil. The diameter of the rubber film in the radial loading cylinder (2) is 50 mm, with an area of 19 63 cm2, when the oil pressure is 12 The total thrust that can be generated at 74 MPa is 25 kN. The ratio of the thrust of the radial loading cylinder to the weight of the weight and the weight of the hooks and other parts used to place the weight on the pressure regulating valve is 20 25:1.

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1- Hydraulic pump station; 2- Unidirectional throttle valve; 3- Energy storage device; 4- Electric contact pressure gauge; 5- Stop valve; 6- Pressure regulating valve; 7- Electromagnetic directional valve; 8- Pressure gauge; 9- Radial oil cylinder

Figure 2 Schematic diagram of ABLT-7 testing machine loading system

2.3 Monitoring System

The ABLT-7 testing machine monitoring system can monitor the vibration and temperature of the test bearings and achieve out of bounds shutdown. The sensor transmits the measured bearing vibration and temperature signals to the signal amplifier, which is processed by the industrial computer and displayed on the monitor. When the bearing fails or the testing machine is abnormal, the monitor transmits the failure information to the computer, which automatically shuts down the running testing machine and saves the previous monitoring data. The principle of the monitoring system is shown in Figure 3 shows the interface of the monitoring system.

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Figure 3 ABLT-7 Testing Machine Monitoring Interface Diagram

3. Experimental application

In order to verify the validity of the experimental data, the ABLT-7 testing machine should be first evaluated according to the standard, and then the qualified testing machine should be used for experimental verification. Due to the lack of relevant national and industry standards, the ABLT-7 testing machine is identified using the self calibration procedure of the rolling bearing life testing machine from the National Testing Laboratory of Hangzhou Bearing Test and Research Center (CNAS No. L0309).

Using the identified and qualified ABLT-7 testing machine, experiments were conducted on UCP207 (8 sets each) with outer spherical ball bearing units produced by three different manufacturers provided by a certain company. The test conditions were as follows: a speed of 2000 r/m in and a radial load Fr=6 533 kN, axial load Fa=0, Cr = 19. 8 kN, The rated life L10 is 232 hours, and the lubrication method is manufacturer B's original grease lubrication. Manufacturers A and C continuously inject grease lubrication. The test data is shown in Table 1.

The test results showed that all inner rings of manufacturer A bearings experienced fatigue peeling, and two sets of inner rings of manufacturer C bearings experienced fatigue peeling. The remaining bearings did not fail and the test was stopped. Unlike manufacturer A and C bearings, manufacturer B bearings do not require grease injection during testing due to their original grease lubrication. Six sets of bearings experienced grease failure, resulting in an increase in bearing temperature, burning and discoloration of the steel ball surface and inner and outer ring channels, and damage to the retaining frame; The other two sets of bearings experienced inner ring failure. The experimental results indicate that, The test data of ABLT-7 bearing life and reliability enhancement testing machine is valid and consistent with reality, and can be applied. But the test results can only reflect whether the testing equipment can simulate the real use of bearings.

4. Conclusion

The ABLT-7 type bearing life and reliability enhancement testing machine can meet the life and reliability enhancement testing of Bearing Unit, and can also perform limit speed and leakage temperature rise tests, further enriching and improving the ABLT enhancement testing machine product series. Heating or cooling devices can also be added to expand the ABLT-7 testing machine in a modular manner to simulate the testing environment, improve the feasibility of the external spherical bearing strengthening simulation test, and ensure the reliability of the test data.

2025 April 3rd Week FK Product Recommendation:

722500 DA/DB:

The 722500 DA/DB is a type of Plummer Block (bearing housing) designed to support rotating shafts with rolling bearings. It features:

Robust cast iron or steel housing, suitable for heavy-duty applications.

DA/DB variations may refer to different sealing or mounting designs (e.g., DA with set screws, DB with double seals).

Easy installation and maintenance, ideal for industries like conveyors, motors, fans, and mining equipment.

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