1 Bearing life The total number of revolutions in operation before fatigue pitting of any element in a single rolling bearing or the number of hours working at a certain speed is called bearing life; basic rating life L10: the same batch of bearings work under the same working conditions, among which The total number of revolutions (million revolutions) that 90% of the bearings can run before fatigue pitting occurs or the number of working hours at a certain speed (10% failure probability); bearing life calculation formula: unit: h Test speed n: 20 %~60% test load P: 20%~35% test sample capacity: generally take 8~20 sets, and prepare 5~10 sets as spare samples; 2 Purpose of life test: Find the defects of the bearing itself, in order to further improve Bearing life provides data support, because the design, manufacture and application of the product will affect the life of the bearing. The factors affecting the service life of the bearing can be divided into two categories: the first category: the bearing itself, such as material, machining accuracy, heat treatment and so on; the second category: the application itself, such as wrong installation, bad working conditions (speed, working temperature, environment, etc.), etc.; • Test the fatigue life of the bearing to obtain the bearing-related life reliability level; • For the research and development of the bearing 3. Test method complete test: a set of bearing samples, all tested to failure under the same test conditions; truncated test: a set of bearing samples, part of which is tested under the same test conditions Test to failure; test equipment internal structure principle of test equipment Test machine structure schematic diagram, including frame parts, test unit, drive system, radial loading system, axial loading system, lubrication system, cooling system, high temperature generation system, measurement and control system and other components. The test unit consists of a test cavity and a test head. The test cavity is fixed on the flat plate in the frame part; the test head is installed in the test cavity, which mainly consists of the end load body, the middle load body, the test mandrel, the middle bushing, the end bushing, the spacer ring, the disassembly ring, the lock It consists of a tight nut and a test bearing. Test tooling assembly Figure 4 The test test equipment should generally run continuously, and the whole process of the test (load, speed, vibration, current, temperature, temperature rise) should be monitored, and the parameters of the equipment itself should be controlled within the required range. Protection, prevent accidental damage to equipment during the test process, and also control the failure of the bearing at the initial stage, which is conducive to the analysis of failure causes and proposes improvement directions; during the test process, the speed, load, temperature, vibration, and current sensors are used in the test process. The relevant parameters are monitored and transmitted to the monitoring software to summarize and display that the corresponding heaters need to be added to the working conditions that require thermal insulation testing (add 'heating strips' to the test unit for grease lubricated bearings for heating, and the oil lubrication test achieves its purpose by heating the lubricating oil. ). test end load&The rotational speed records the changes of the working conditions of the bearing in the test one by one, such as the stability and change trend of the rotational speed n, radial load Gr, and axial load Ga at each time point, to ensure the accuracy and stability of the test conditions; The vibration of the entire test fixture is recorded, and the vibration value at each moment is recorded. The vibration trend change in the entire test can track the state of the bearing throughout the test, whether there is any abnormality and abnormal trend change, and analyze which bearing is in the test. During the test, an abnormality begins to occur, whether there is slippage, etc.; the current is used to monitor the current state, the trend of current change, and whether there is overload during the test; the temperature and temperature rise of each set of bearings are monitored one by one. Make a detailed record of the temperature condition of each set of bearings at each time point, and form a trend for the temperature change of the whole test, whether there is abnormal high temperature, etc.; 5. Analysis and failure of test pieces 6. Reliability evaluation Reliability is also called reliability, which refers to The ability of a product to perform a predetermined function within a specified time and under specified conditions, including structural safety, serviceability and durability. Best linear invariant estimation a) Complete test b) Censored test When r=N, it is a complete test; according to b, v to estimate L10t, L50t and Re basic rated life test value: reliability: qualified judgment 1) L10t , Re data is generally accurate to two significant figures; 2) L10t/L10h≥Z is qualified, where Z=1.4 for ball bearings, Z=1.2 for roller bearings and self-aligning ball bearings; 3) According to the quality requirements, proceed as follows Conformity assessment, in the long-life test, the test report should also give the value of the qualified multiple; verification test: the qualified life is qualified for the verification test; qualification test: the qualification test is qualified when the qualified life is 3 times. (Source: CHIPRO Industrial Services)