Q1:Why regular maintenance of linear bearings?

A: Maintenance of linear bearing: cleaning of linear bearing: when disassembling the linear bearing for maintenance, first record the appearance of linear bearing, confirm the residual amount of smoothing agent, and wash the linear bearing after sampling the smoothing agent used for inspection. As a cleaning agent, gasoline and kerosene are commonly used. The cleaning of the removed linear bearing is divided into coarse cleaning and fine cleaning, respectively placed in the container, first put on the bottom of the metal net, so that the linear bearing does not directly contact the dirt of the container. In rough cleaning, if the linear bearing rotates with dirt, it will damage the rolling surface of the linear bearing, and should be paid attention to. In the crude cleaning oil, the use of brush to remove smooth grease, adhesion, roughly clean, into the fine washing. Fine cleaning, is the linear bearing in the cleaning oil while rotating, while carefully cleaning. In addition, the cleaning oil should always be cleaned.

linear bearing health care: in order to maintain the original performance of linear bearing in good condition for as long as possible, it is necessary to health care, maintenance, in order to prevent accidents, to ensure the reliability of operation, progress in consumption, economy.
It is best to take care of the operation specifications corresponding to the operating conditions of the machinery and stop regularly. The contents include monitoring operation status, replenishment or replacement of smoothing agent, regular disassembly inspection. Maintenance matters in operation, including rotary sound, vibration, temperature, smooth agent state of linear bearings and so on.

The maintenance and identification of linear bearing: in order to determine whether the disassembled linear bearing can be used, the linear bearing should be checked after cleaning. Check the state of raceway surface, rolling surface, matching surface, wear condition of the adhere frame, increase of linear bearing clearance and damage of independent size accuracy landing, abnormal. For non-separation type small ball bearings, use one hand to support the inner ring and rotate the outer ring to confirm whether it can be fluent. Separate bearings such as tapered roller linear bearing can inspect the raceway surface of rolling body and outer ring separately. Large linear bearings can not be rotated by hand, pay attention to check the appearance of rolling body, raceway surface, adhere to the frame, flay surface, the higher the importance of linear bearings, the more careful inspection.
1, the force of the resultant force through the axis of the linear bearing as far as possible, which requires the average symmetry and stability of the force point, through the sphere or parallel to the axis of the force.
2, the size of the force should be smooth and average, should not have impact, this requires the use of oil pressure or can apply a smooth tension or pressure tool, really have to use the hammer, but also through the copper sleeve and other soft metal without falling chip to buffer, knock force as gentle as possible. It is best to use copper rod or copper hammer to stop hammering.
3, prevent the application of force through the rolling body, which requires the installation and removal of the inner ring (shaft ring) through the inner ring force, installation and removal of the outer ring) through the outer ring force.
4, the drag force should continue to the due level, for example, in the device of linear bearing to stop the force when the linear bearing is just installed in the correct position, to ensure that the end face of the ring (washer) against the seat hole or the shoulder end face of the shaft, can not be squeezed too tight, and can not be installed in place.

Q2:What is double row tapered roller bearing and where is it used?

A: The tapered roller bearing belongs to the separation type bearing, and the inner and outer rings of the bearing have tapered raceways. This kind of bearing is divided into single row, double row and four row tapered roller bearings according to the number of rows of rollers. Single row tapered roller bearings can withstand radial load and axial load in a single direction. When the bearing bears the radial load, an axial component force will be generated, so another bearing that can bear the opposite axial force is needed to balance it.
Widely used in automobile, rolling mill, mining, metallurgy, plastic machinery and other industries.

Q3:What are sliding bearings?

Bearings according to the friction properties of bearing work can be divided into: sliding bearings and rolling bearings.
The bearings that use the sliding motion of the shaft and bearing to bear the load are called sliding bearings. According to the different principle of oil film formation on two relative moving surfaces of sliding bearings. It can be divided into hydrodynamic lubrication bearings (also known as dynamic pressure bearings) and hydrostatic bearings (also known as hydrostatic bearings). The general discussion is hydrodynamic lubrication bearings, which bring oil between the two surfaces through the relative movement of the shaft and the bearing, forming enough pressure film to separate the two surfaces, so as to bear the load.
Under the condition of liquid lubrication, the sliding surface is separated by the lubricating oil without direct contact, which can greatly reduce the friction loss and surface wear, and the oil film also has a certain vibration absorption capacity. But the starting friction resistance is large. The part of the shaft supported by the bearing is called the journal, and the parts that match the journal are called the bearing bush. In order to improve the friction properties of the bearing bush surface and cast on the inner surface of the anti-friction material layer called bearing lining. The material of bearing bush and bearing lining is collectively referred to as sliding bearing material. Commonly used sliding bearing materials are bearing alloys (also known as Babbabel alloy or white alloy), wear-resistant cast iron, copper and aluminum base alloys, powder metallurgy materials, plastics, rubber, hardwood and carbon-graphite, polytetrafluorethylene (PTFE), modified polyformaldehyde (POM), etc. The application of sliding bearing is generally in low speed and heavy load conditions, or it is difficult to maintain and fill lubricating oil.
Compared with rolling bearings, sliding bearings have the advantages of high bearing capacity, good vibration resistance, stable and reliable work, low noise, long service life, etc. It is widely used in internal combustion engines, rolling mills, large motors and instruments, radar, astronomical telescopes and so on.

Q4:What are the main materials for manufacturing bearings

A: 1. Materials for ring and rolling element
(1) High carbon chromium bearing steel
Most bearing rings and rolling elements are made of special steel. The ring and rolling element are manufactured from high carbon chromium bearing steel (GCr15 and GCr15SiMn and ZGCr15 and ZGCr15SiMn). The hardness of the parts is as follows:
The rings and rollers made of GCr15 and ZGCr15 materials are HRc61~65, and the steel balls are HRc62~66.
The rings and rollers made of GCr15SiMn and ZGCr15SiMn materials are HRc60~64, and the steel balls are HRc60~66.
Bearings made of high carbon steel chromium bearing steel are generally suitable for working temperature range of -40~130 degrees, oil and grease lubrication is normal. It can meet the requirements of general machinery.
High carbon chromium bearing steel bearing parts after high temperature tempering, its adapt to the working temperature up to 250 degrees.
With the progress of smelting technology, different smelting methods can be used for high carbon chromium bearing steel, such as vacuum smelting technology, which can greatly reform the internal quality of steel, especially the oxygen content in steel and the non-metallic inclusions formed by it have been significantly reduced. The fatigue life of bearings made of this high carbon chromium bearing steel can be increased exponentially.
According to a large number of test comparison data show that different smelting methods obtained GCr15, GCr15SiMn, ZGCr15, ZGCr15SiMn bearing steel manufacturing bearings.
(2) Carburized bearing steel
Carburized bearing steel and other manufacturing ring and rolling body, the hardness is: ring and rolling body HRc60~64, generally suitable for the working temperature of -40~140 degrees Celsius range, oil and grease lubrication normal, can be used in large impact vibration conditions, such as rolling stock and rolling mill bearings, but the heat treatment process of the steel is more complex.
(3) Heat-resistant bearing steel
The rolling element of the ferrule made of heat-resistant bearing steel has the hardness of HRc60~64 for ferrule and roller, and HRc61~65 for steel ball. Under the condition of normal lubrication, it is suitable for the working temperature of 120~250 degrees Celsius, such as the working conditions of the main shaft of aeroengine and gas turbine.
(4) Corrosion resistant bearing steel
Make ferring and rolling element with corrosion-resistant bearing steel, its hardness is: ferring and rolling element should not be lower than HRc58, suitable for water, nitric acid, chemical reagents and other corrosive media, the temperature is -253~350 degrees Celsius.

2. Materials for cage
   (1) The vast majority of bearings are made of steel cage, the most widely used is low carbon steel plate stamping wave shape, basket shape, box shape and other cage, suitable for high carbon chromium bearing steel bearing conditions and environment; The cage stamped with medium carbon stainless steel plate is suitable for bearing conditions and environment with corrosion resistant bearing steel.
   (2) Excellent and smooth surface quality of non-ferrous metals. For working at high temperature, the physical cage can be made of silicon bronze, and the working temperature can reach 315 degrees Celsius; Because the strength of aluminum is lower than that of brass and the specific gravity is light, aluminum is commonly used to make solid cage instead of brass, which is mainly suitable for high speed, light specific gravity and corrosion resistance.
   (3) With engineering plastics manufacturing cage, in recent years has been greatly developed, mainly because it has a certain corrosion resistance, good self-lubrication performance, small friction resistance, convenient material, cheap price, easy to manufacture and other advantages, but easy to “aging”. The current use of reinforced nylon 66 is the most widely used, it can continue to work in the temperature range of -40~120 degrees Celsius.
   Ptfe has high strength, good self-lubrication performance, continuous working temperature up to 300 degrees Celsius, phenolic adhesive has high mechanical strength, good wear and heat resistance, but expensive cost, suitable for high-speed spinning, working temperature of -40~150 degrees Celsius, instantaneous up to 180 degrees Celsius.