Quality Joint Bearing

The accuracy of rolling bearings is divided into (main) dimensional accuracy and rotational accuracy. The accuracy grades have been standardized and are divided into six grades: 0 grade, 6X grade, 6 grade, 5 grade, 4 grade and 2 grade.    Accuracy increases sequentially from grade 0, and grade 0 is sufficient for general purposes, but when used in the conditions or occasions shown in Table 1, an accuracy of grade 5 or higher is required.    Although the above precision grades are formulated based on ISO standards, their names are different in national standards.Dimensional accuracy (items related to shaft and housing installation)1. Allowable deviation of inner diameter, outer diameter, width and assembly width2. Allowable deviation of inner compound circle diameter and outer compound circle diameter of roller group3. Allowable limit value of chamfer size4. Allowable variation of widthRotation accuracy (items related to the beating of rotating body)1. Allowable radial runout and axial runout of inner and outer rings2. The allowable lateral runout of the inner ring3. The allowable variation of the inclination of the outer diameter surface4. Allowable variation of thrust bearing raceway thickness5. The allowable deviation and allowable variation of the tapered holeBearing type and applicable precision classBearing type Applicable standard Applicable precision classDeep groove ball bearing GB307 Grade 0 Grade 6 Grade 5 Grade 4 Grade 2Angular contact ball bearings Class 0 Class 6 Class 5 Class 4 Class 2Self-aligning ball bearing Class 0Cylindrical roller bearings Class 0 Class 6 Class 5 Class 4 Class 2Tapered roller bearings Metric series (single row) GB307 Grade 0 Grade 6 Grade 6 Grade 5 Grade 4Metric series (double row, four row) SB/T5341994 Grade 0Inch series SB/CO/T1089 Class4 Class2 Class3 Class0 Class00Spherical roller bearing GB307 grade 0Thrust ball bearings Class 0 Class 6 Class 5 Class 4Thrust spherical roller bearings Class 0The GB/T30794 standard divides the bearing grades into G E D C B. ISO, JIS and other standards are compared as follows:Standard AccuracyGB/T30794 B C D E GISO CLASS2 CALSS4 CLASS5 CLASS6 NORMAL CLASSDIN P2 P4 P5 P6 P0ANSI ABEC9 ABEC7 ABEC5 ABEC3 ABEC1JIS JIS2 JIS4 JIS5 JIS6 JIS0Selection of precisionPerformance Requirement Use Case Applicable Accuracy ClassIt is required to place the object with high runout accuracy. Audio and video machine spindles (video recorders, tape recorders)Radar, parabolic antenna shaftMachine tool spindleElectronic computer, disk spindleAluminum foil roll neckMulti-stage rolling mill support bearingsP4P5, P4, P2, ABEC9P5, P4, P2, ABEC9P5P4High-speed rotation superchargerJet engine main shaft, auxiliary machinecentrifugeLNG pumpTurbomolecular pump spindle, protected bearingsMachine tool spindleTensioners P5, P4P5, P4P5, P4P5P5, P4P5, P4, P2, ABEC9P5, P4 Small friction and friction change are required to control machines (synchronous motors, servo motors, gyro gimbals)MeterMachine Spindle P4, ABMA 7PP5P5, P4, P2, ABEC9General accuracy Small motors, gear transmissions, cam transmissions, generators, low-inductance synchronous servo motors, pressure rotors, printers, copiers, testing instruments P0, P6

Quenching of steel is a heat treatment process in which the steel is austenitized and cooled at an appropriate cooling rate, so that the martensitic unstable structure transformation occurs in the cross section of the workpiece or within a certain range.1. Process flow of quenching workpiece    General workpiece: quenching→cleaning→tempering→sandblasting (or shot blasting, etc.) surface cleaning→inspection.    Shaft parts and deformable workpieces: quenching → cleaning → tempering → straightening → stress relief treatment → sandblasting → inspection.2. Preparation before quenching(1) Check the quantity, material and size of workpieces, and check whether there are cracks, bruises, missing edges, sharp edges, sharp corners and corrosion on the workpieces that affect the quenching quality.(2) According to the drawings and process documents, specify the specific requirements for quenching, such as hardness, local quenching range, etc.(3) According to the quenching requirements, design and select suitable tools and fixtures, and some workpieces should be properly bound, and corresponding protective measures should be taken at the parts that are prone to cracks, such as wrapping and blocking holes with iron sheets or asbestos ropes.(4) Workpieces that are not allowed to be oxidized or decarburized on the surface should be heated in a salt bath furnace or a pre-evacuated protective atmosphere furnace, or the following protective measures should be taken:  a. For paint protection, the following paint formulations are recommended:    ① 10% graphite + 90% grease (mass fraction).    ② 100gSiO2+5gAl2O3+25gNaSiO3+40gH2O. Thermal coating 0.05~0.10mm, when the heating temperature is less than 1050 ℃, it has anti-oxidation and decarburization effects.    ③ 20gSiO2+10Al2O3g+10g feldspar 10gCr2O3+10gSiC+8gKSiO3+12~15gH2O0 thermal coating 0.2~0.30mm, when the heating temperature is less than 1200 ℃, it has anti-oxidation and decarburization effects.  b. Put the workpiece into an iron box filled with charcoal or used cast iron chips, and seal it with a cover.(5) A large number of workpieces must be quenched individually or in small batches. After the process is formulated, batch quenching can be carried out, and random inspections are often carried out during the production process.3. Furnace loading(1) Workpieces of different materials but with the same heating process are allowed to be heated in the same furnace.(2) The furnace-loaded workpieces should be dry and free from oil and other dirt.(3) When workpieces with different cross-sectional sizes are loaded into the same furnace, the large workpieces should be placed at the rear of the furnace, and the holding time of large and small workpieces should be calculated separately.(4) When loading the furnace, the workpieces must be regularly placed on the furnace rack or the furnace floor, and stacked with hooks, pliers or special tools. Do not throw the workpieces directly into the furnace, so as not to hurt the workpiece or damage the furnace lining.(5) The slender workpiece must be hung and heated vertically in a pit furnace or salt furnace to reduce deformation.(6) When the workpiece is heated in the box furnace, it is generally arranged in a single layer, and the gap between the workpieces is 10~30mm. Small pieces are allowed to be properly stacked, but the heat preservation time should be appropriately increased.4. Heating1. Heating method(1) Carbon steel and alloy steel workpieces can generally be directly heated in a furnace that is 20~30°C higher than the specified quenching temperature.(2) High-carbon high-alloy steel and workpieces with complex shapes should be preheated first.2. Heating temperature selection.3. Calculation of workpiece heating time: the workpiece in the furnace should be kept within the specified heating temperature range for an appropriate time to ensure the necessary tissue transformation and diffusion. The heating time refers to the time for the entire heating process from the time when the workpiece is loaded into the furnace, powered on and heated until it is released from the furnace.The heating time is related to the effective thickness of the workpiece, steel type, furnace charging method, furnace charging amount, furnace charging temperature, furnace performance and sealing degree and other factors.4. Selection of effective thickness (applicable to both annealing and normalizing processes)(1) Round rod workpieces are calculated by diameter.(2) Flat workpieces are calculated by thickness (the upper limit of thermal insulation coefficient is selected).(3) The solid cone is calculated according to the diameter at the height of 1/3 from the big end.

Bearings are important components in vehicles and play a vital role in the operation of vehicles. In many cases, vehicle bearings will have certain failures. China Bearing Network (referred to as: Bearing Network) will share a typical failure of vehicle bearings-peeling phenomenon. And tell everyone how to better test the quality of the bearings, so that the bearings are safer to use.1. Typical failure of vehicle bearings - peeling phenomenon.After decomposing the faulty bearing, it was observed that the working surface of the bearing roller was peeled off, but the edge of the roller was dropped. The working surfaces of the inner and outer rings of the bearing also had metal flakes, and pits also appeared on the working surfaces of the inner and outer rings in contact with the edge of the rollers, as shown in Figures 1 and 2. The bearing cage has also been severely damaged and broken, and plane scars have appeared on the upper plane of the cage.2. Cause analysis of bearing failureFor the analysis of the damage characteristics of the bearing, the basic reasons for the bearing failure mainly include the following aspects:1) Contact fatigue damage.2) The bearing is subjected to abnormal loads such as excessive contact load or impact load. For example, when the molten iron car is subjected to a large impact load during desulfurization or hanging tank operations; The effect of the load.3) Improper bearing assembly or too small clearance, resulting in excessive additional contact stress between components.4) Poor lubrication. Due to the harsh maintenance environment of metallurgical enterprises, iron slag, cotton yarn, dust and other foreign matter are mixed into the lubricant during bearing maintenance.3. Measures to improve the quality of bearing inspection1) Appropriate selection of bearing clearanceClearance is an important factor for the normal operation of rolling bearings, and it is divided into axial clearance and radial clearance. Choosing an appropriate clearance can make the load reasonably distributed among the rolling elements of the bearing, limit the axial and radial displacement of the shaft (or shell), and ensure the rotation accuracy of the shaft; it can make the bearing work normally under the specified temperature; Reduce vibration and noise, which is beneficial to improve the life of the bearing. Therefore, when selecting a bearing, an appropriate bearing clearance must be selected. The selection of bearing clearance should consider the working conditions of the bearing, such as load, temperature, speed, etc.2) Improve the quality of bearing assembly①Matching and measuring link: When assembling the bearing, making the correct matching is an important factor to ensure the reasonable bearing clearance, but the current measurement means and tools are very single, and it is impossible to accurately match the bearing. Purchasing more advanced measurement tools at present; after the bearing is assembled, it needs to go through the process of clearance measurement, but it has not yet been implemented due to the limitations of tools and measurement technology. It is recommended to add this process.②Operation inspection link: After the bearing is installed, it should be inspected to ensure that the bearing is installed in place, the rotation is flexible, and there is no stagnation. If the bearing is installed improperly, the temperature of the bearing will rise rapidly and be damaged, and even major accidents such as bearing seizure and fracture will occur. It is recommended to increase the bearing running and inspection process.3) Improve bearing maintenance and storage environment① Overhaul environment: Due to the particularity of the overhaul environment of metallurgical enterprises, there are a lot of iron dust and dust in the overhaul environment, so when the bearing is overhauled, the surrounding environment should be kept clean and free from hand sweat and dirt.②Storage environment: Bearings should not be stored directly on the ground (more than 30cm above the ground), avoid direct light and cold walls. In order to prevent rust, store in an environment with a temperature of about 20°C and a humidity of less than 65%. Bearings placed in acidic air are prone to rust and discoloration, so it is necessary to strengthen bearing storage management to ensure that new bearings are not damaged by external factors.4) Standardized disassembly and assembly of axle boxesAt present, the maintenance work of bearings is relatively extensive, especially in the process of disassembling and assembling the axle box. Sometimes a sledgehammer is used to strike, which may cause internal damage to the bearing and shorten the working life of the bearing. Therefore, while strengthening the management of bearing maintenance, it is necessary to Actively go deep into the front line to understand the situation, effectively improve the problems found, develop corresponding maintenance tooling, and improve the quality of bearing maintenance.5) Eliminate the loading of inferior bearings from the source①External packaging inspection: In general, genuine factory brands have their own dedicated designers to design the external packaging, and arrange factories that pass the production conditions to produce and produce. Therefore, the packaging is very clear from the lines to the color blocks.②Steel printing inspection: Usually, the bearing body is printed with brand words, labels, etc., and the fonts are very small. However, most of the products produced by the original factory use steel printing technology, and the characters are embossed before heat treatment, so although the fonts are small, they are deeply concave and very clear. The fonts of counterfeit products are not only blurry, but also have rough printing techniques, floating on the surface, and can even be easily erased by hand.③ Rotation check: hold the inner sleeve of the bearing with the left hand, turn the sleeve with the right hand to make it rotate, and listen for noise. Due to the backward production conditions of most counterfeit products, or even completely manual workshop operation, it is inevitable that sundries such as sand will be mixed into the bearing body during the production process, so there will be noise when rotating. This is the biggest difference from genuine factory brands that strictly enforce production standards and operate with machines.④Surface quality inspection: Since the current anti-rust technology in China is not particularly qualified, it is easy to leave thick oil stains when anti-rust treatment is carried out on the bearing body, which is sticky and sticky when held in the hand. There are almost no traces of anti-rust oil on the bearings. A particularly careful expert said that the imported bearings smell a certain smell, and there must be anti-rust oil, but they cannot be seen.

1. The present invention relates to the technical field of automobile clutches, in particular to a driven disc assembly.Background technique:2. The inner ring of the car is another part of the clutch, which transmits the torque of the engine to the transmission through friction conversion, reduces the vibration and impact of the drive train, and completes the tasks of "disengagement" and "combination". The inner ring of the automobile clutch is an essential consumable part of the manual transmission step-change car. When in use, the driven disc assembly transfers the torque of the engine to the transmission through friction conversion. At present, most clutch driven disc assemblies on the market use Friction plates made of organic friction materials, when the car starts with too much energy or overloads, it is easy to cause the friction plates to burn out; secondly, it is affected by the material and manufacture of the friction plates.3. In the prior art, the strength of the inner ring of the clutch is relatively low, so that when the clutch is hit by a collision, the inner ring is prone to collision damage, thereby shortening the service life; on the other hand, the wear resistance of the existing clutch inner ring is poor, It is subject to friction for a long time during use, which is prone to friction damage and shortens the service life.4. Chinese patent cn201811374803.8 discloses "a clutch driven disc assembly with a reinforced protective device", which includes a large steel plate of the clutch driven disc, a clamping disc and a clutch reinforcement plate. The clutch reinforcement plate is set close to the engine flywheel The large steel plate of the clutch driven plate assembly on one side is fixed together with the large steel plate of the clutch driven plate assembly and the clamping plate through rivets.Based on the ordinary clutch driven plate assembly, this technology installs a clutch reinforcing plate on the side close to the engine flywheel, and uses riveting to fix the large steel plate of the clutch driven plate assembly and the clutch reinforcing plate together. Strengthen the axial rigidity and strength of the clutch driven disc assembly, reduce the failure rate caused by stiffness and strength and improve the wear resistance of the clutch driven disc assembly, but the traditional split wave plate is still used when using, which will cause The heat dissipation effect of the driven plate assembly is not good, which leads to the burning of the friction plate.\