Cause bearing failure caused

According to the bearing surface grinding metamorphic layer formation mechanism, the impact grinding metamorphic layer of the main factors is the grinding heat and grinding force. The following analysis on the reasons for bearing failure.

1 bearing the grinding heat

The roller bearing grinding, the grinding wheel and the workpiece contact area, consume large amounts of energy, resulting in a large number of grinding heat, causing the local instantaneous grinding zone temperature. Use of linear motion heat transfer theory derivation, calculation or application infrared and thermocouple method measured the instantaneous temperature under experimental conditions can be found in the 0.1 ~ 0.001ms instantaneous temperature within the grinding zone up to 1000 ~ 1500 ℃. Such instantaneous temperature, a certain depth sufficient to work the surface layer of high temperature oxidation, amorphous structure, high-temperature tempering, secondary hardening, cracking and other changes or burns.

(1) the surface oxide layer

The instantaneous high temperature steel surface under the role of oxygen in the air, up into very thin (20 ~ 30nm) thin layer of iron oxide. It should be noted that the oxide layer thickness and the total thickness of the surface layer of grinding deterioration test results showed a corresponding relationship. This shows that the thickness of the oxide layer which is directly related with the grinding process, the grinding quality is an important symbol.

(2) amorphous tissue layer

Instantaneous grinding zone so that the surface temperature reaches a molten state, the molten metal molecular flow has been evenly coated on the work surface, and is the base metal at breakneck speed cooling, forming a thin layer of amorphous tissue layer. It has high hardness and toughness, but it is only about 10nm, it is easy to be removed precision grinding.

(3) high-temperature tempering layer

Instantaneous grinding zone temperature to a certain depth can (10 ~ 100nm) is heated to a temperature above the tempering heating the workpiece. Does not reach the austenitizing temperature in the case, as the heating temperature is increased, the surface layer by layer will be generated corresponding to the temperature of the heating or tempering retempered organizational changes, hardness is decreased. The higher the heating temperature, the hardness decreased also more powerful.

Type of angular contact ball bearings

Angular contact ball bearings: 7000C-type (α = 15 °), 7000AC type (α = 25 °) and 7000B (α = 40 °) of several types. This kind of bearing locking in the outer ring, inner and outer rings can not be separated, can be combined radial and axial loads and axial loads in one direction. Axial load capacity determined by the contact angle, the contact angle is larger, the ability to withstand high axial loads. This kind of bearing shaft or housing to limit axial displacement in one direction. Contact ball bearing high speed limit, you can support radial load and axial load can also be subject to pure axial load, axial load capacity determined by the contact angle, and with the contact angle increases.
Single row angular contact ball bearings
Single row angular contact ball bearing can withstand axial load in one direction, the radial load, will cause additional axial force must be applied to the corresponding reverse load, therefore, the types of bearings are generally used in pairs. Double row angular contact ball bearings can withstand greater radial load mainly radial and axial joint load and moment load, it can limit the bi-axial displacement of shaft or housing, the contact angle of 30 degrees.
Angular contact ball bearings installed in pairs
Installed in pairs of angular contact ball bearings can bear radial load mainly radial and axial joint load can also be subject to pure radial loads. Tandem configuration can only bear axial load in one direction, the other two configurations can withstand axial load in either direction. This type of bearings are generally manufacturers matching pairs of user submitted after installation preload interference, rings and balls in the axial pre-load condition, thereby enhancing the entire group as a single bearing support stiffness and rotation Accuracy

The materials used slewing

ring and rolling element materials
Under normal circumstances, slewing bearing using-hardened carbon chromium bearing steel. Or GCr15SiMn GCr15 steel grades for manufacturing; slewing rings hardened steel is used when the user no special requirements, generally used in 50Mn steel, but sometimes in order to meet some of the needs of specific application hosts can also be provided by user specific conditions of use use other brands of hardened steel.
cage materials
Slewing ring with a cage with the overall style, segmented, isolated block structure of the form. Where overall style and segmented cage with 20 gauge steel or cast aluminum alloy ZL102. Isolated block 1010 by polyamide resin, ZL102 cast aluminum and other manufacturing.
seal material
Slewing ring with oil resistant nitrile rubber material used manufacture.

Talking grinder hydrostatic bearing maintenance experience

Rotary hydrostatic bearing its high accuracy, good rigidity, high capacity, no wear, high durability and is widely used M210, M131W, 3160A grinder and 2A710, FYT10 Diamond boring head. With the development of digital technology, hydrostatic bearings are also widely used in machining centers, CNC machine tool spindles. YTO AG first engine plant, there are many static pressure and static pressure diamond grinder boring head, in the maintenance carried out some exploration and attempts to obtain experience points.

Orifice restrictor (a) outside the internal throttle to throttle, and to install the upper and lower chamber pressure gauge real-time display. So easy maintenance, in particular, can easily be cleaned regularly, this is an internal restrictor unmatched. (2) throttling ratio. Throttling than the theoretical value of β is 1.2 to 1.5, and 1.25 based on years of experience with preferred. So that the maintenance, the need for geometric precision spindle, bearing around the geometric accuracy, concentricity, roundness and taper strictly controlled in order to ensure β values. According to the carrying capacity of the machine to determine the value of e (the geometric center of the spindle and bearing eccentricity), the β value best. (3) is not installed in the oil chamber spindle, each column of oil out of the oil port must be consistent (observation), if not, should be taken to change the restrictor aperture methods to alter the flow. With 4 cavities, for example, generally lower, left and right chamber of the oil column at between 20 ~ 25mm, hole diameter of 0.25 ~ 0.4mm.

Thin film feedback Feedback restrictor throttle special bearing stiffness is great, but the machine in operation often appear hold tile, brushed, lost pressure and so on. The most critical is the feedback film film practice that locking bush, brushed the main reasons are: ① thin plastic deformation due; ② feedback slow. External load mutation, the film did not react when the axis and tile has been rubbed; ③ film fatigue. Film using a long time, fatigue deformation, the equivalent of changing the feedback parameters. Increasing film thickness and use some of the fatigue resistance of the material, can receive good results. Generally rigid film, a pre-load, reserve gap approach. Specific approach is: the 1.4mm thick rigid 4mm thick film to film, the inferior vena pad 0.05mm thick aluminum foil, so that the spindle than the ideal position to adjust to the high position of 0.05mm. Purpose is force when the spindle (wheel weights, cutting force) after return exactly to the ideal center.

Hydrostatic bearing oil supply system improvement in the fuel supply system, in addition to the coarse filter, fine filter, the rest of the components have a protective effect on the hydrostatic bearing. On the basis of the original system, fuel system improvements. (A) in the throttle plate after the oil pressure switch and pressure gauge connection port (the original in the accumulator in front), so that the operator can see the chamber pressure and the size of the inlet pressure. When the pressure is greater than a certain value, in order to immediately shut down, in order to avoid bearing locking. Such as: inlet pressure 2MPa, exit chamber pressure 1.2 ~ 1.6MPa, 1.2MPa below will shut down. (2) increasing the number of detection means hydrostatic bearing between the shaft and the bearing gap of 0.04 ~ 0.05mm, during which the oil has a certain resistance value of the resistance variation detection, it can learn the size of the gap . With spindle pole, bush for another pole, measure the resistance change. After processing this signal sent to the photoelectric alarms and control system amplifier, controls the spindle motor start and stop, in order to avoid friction axis and tile.

Sliding bearing pad material and structure

Sliding bearing bush materials and structures Abstract: sheet metal fixture design the automatic lathe turning 3Cr13 stainless steel parts auto stringer processing technology and equipment selection composite thread cutting cycle G76 command coordinate system and the direction of motion profile gantry WEDM decoding software simulation program design is based on UG CAD / CAM capabilities of the new mouse design and manufacturing machine Xiazuo Association: towards "quality service brand association" principle introduced Seiko continue efforts to launch low-power inverter high ripple rejection Voltage Regulator is rolling wheel Mixer procedures developed bearing ultra-precision machine tools for metal cutting fluid waste breakthrough treatment CITIC Heavy Machinery and Qi a machine made of heavy-duty double column vertical lathe cylinder head valve seat and the conduit hole processing technology AC610M / AC630M turning grade precision CNC milling typical CAM platform application programming features contrast world machine tool industry development direction of how to solve the Chinese full parsing Pro / E after AutoCAD drawing Chinese characters to the garbage problem detection technology application prospects in the automotive industry structural materials bearing corrosion friction and wear-resistant alloy bearing lubrication strength ability to withstand load bearing parts in direct contact with a relative motion to reduce friction and wear bush material put forward various demands required to meet the following abrasion friction coefficient of friction with sufficient strength to withstand the impact of fatigue strength capability bearing alloy thickness of 0.0130. 13mm sticky load speed bearing lubrication gap is too small surface finish material adverse Note carefully selected matches prevented.

The bearing pad directly in contact with the shaft portion, the shaft having to bear the load and relative motion. To reduce friction, wear on the bearing materials put forward various demands, in addition to requirements of friction between the friction coefficient, wear outside should also meet the following points:

1 should have sufficient compressive strength, fatigue strength and ability to withstand shocks. Bearing alloy having a thickness of (0.013-0.13) mm.

2 block resistance is good. When the load, high speed bearings, bearing clearance is too small, the surface finish is not high, poor lubrication, pay attention carefully selected matching material to prevent friction wear an adhesive glue.

3 with the adaptability and the ability to accommodate foreign matter. Low hardness, good plasticity and low coefficient of elasticity of the material has good adaptability and the ability to accommodate foreign matter.

4 good corrosion resistance, low price, sources foot. After the oxidation of colloidal sediments, have a corrosive effect on the bearing materials.

Bearing basic knowledge and exception handling

Generally inside the bearing inner ring, outer ring, rolling elements and cage composed of four parts. For sealed bearings, further comprising a lubricant and a seal of two parts. Bearing at work, able to withstand the radial load or axial load, at a certain rotational speed, it will produce radial runout or axial runout. According to the working conditions of the bearing used to choose different types of bearings, bearing in order to better play the function, and can extend bearing life.
Life of roll bearings performance, because different purposes, in the required period to maintain their performance. Even though the correct bearing for a particular purpose will, after some time, noise, vibration increases, resulting in decline in accuracy due to wear, grease aging, fatigue, peeling rolling surface can no longer be used. Until these bearings can not be used in a broad sense during the bearing life. Each of them is known as: noise life, wear life, the grease life, the rolling fatigue life and so on.
Why bearing damage? Only a part of the bearing damage in practical applications. Most bearing applications over the life of the machine or the device itself. Bearing damage for many reasons - more than the anticipated load, non-tight seal with or caused by too small bearing clearance and so on. Any one factor has its special form of damage, and will leave special signs of damage. Therefore, to view damage to the bearings, in most cases you can find its possible factors, and based on these findings, the measures taken to prevent recurrence.
Generally speaking, a third of the bearing damage causes damage based on fatigue, another third reason is poor lubrication, the other one-third of contaminants into the bearing or improper installation process. Bearing damage is also associated with different forms of industrial relevance. For example, the electronics industry on the indoor temperature is higher, which requires fans must twenty-four hours operation, the fan bearings are mostly due to material fatigue caused damage; while the pulp and paper industry is mostly due to poor lubrication or bearing damage caused by pollution. Why bearing will fail prematurely? .
    Improper assembly
All kinds of bearing failure in advance, 16% were due to improper assembly and not caused by the use of assembly tools. Some devices require the use of mechanical, hydraulic or heating method for proper and efficient installation and removal. Using special tools and techniques for professional assembly, is to achieve the maximum extension of the machine running time another solution.
Improper lubrication
Although you can install a variety of "maintenance free" sealed bearings, bearings fail prematurely but there are still 36% is due to the incorrect application of grease technology and improper use. Any improper lubrication of the bearings will inevitably fail in advance of normal life. Since the bearing is usually the most difficult mechanical handling equipment part lubrication problem occurs infrequently.
Pollution
Bearings are precision parts, if the bearings and grease contamination will not operate effectively. In addition, as has been marked with grease maintenance-free sealed bearings all use only a small portion of the bearing, so all the early failure of the bearing at least 14% is due to problems caused by pollution.
Fatigue.
If the machine becomes overloaded, use or improper maintenance, the bearings will be affected, leading to premature failure of the bearing, 34% were due to fatigue caused by. Since the bearing in the maintenance of inappropriate or excessive stress would be given "early warning", so the equipment operator or maintenance personnel to observe the operation of the bearing performance anomalies. Why bearings require lubrication? In theory, a good lubrication in the ideal working conditions, the bearing life will always be met, of course, is simply not possible, but if the correct lubrication of bearings, bearing the longest working life. Bearing lubrication to reduce friction and wear within the bearing to prevent the sticking, its lubricating effect is as follows:
1, reducing friction and wear. Constituting the bearing rings, rolling elements and the mutual contact portion of the holder form a film, even in the case of heavy load, but also to prevent the metal contacts, reducing friction and wear.
2, the fatigue life.
Fatigue life of the rolling bearing, the rolling contact surface of the rotary good lubrication, is extended; otherwise, oil viscosity lubricant film thickness of the well bottom, is shortened.
3, the discharge frictional heat and cooling.
Circulating oil to the oil discharge method and the like can be generated by friction heat, the heat coming from the external cooling. Prevent bearing overheating, prevent oil itself aging. .
4, other.
Prevent dust and debris inside the bearing, or to prevent rust, corrosion effect.

Special bearing material selection considerations

Bearing alloys: mainly tin, lead, antimony, or other metals, also known as white metal roll bearings alloy. Because of its good wear resistant, high plasticity, ran together good performance, good thermal conductivity and resistance to rubber and oil resistance and good absorption and therefore suitable for heavy, high-speed case, the bearing strength of the alloy, low price expensive, use must be cast in bronze, steel or cast iron bearing, to form a thin coating.

   1, plastic bearings: plastic bearings have greater compressive strength and wear resistance, commonly used bearings Plastic Bakelite, nylon, PTFE and so on. Lubricating oil and water are available, but also a self-lubricating properties, but poor thermal conductivity.


2, the porous metal material: a porous tissue, the porous metal material is a powder. If it is immersed in lubricant, allowing the pores filled with oil, into oil bearing, self-lubricating properties. Porous metal material toughness is small, only suitable for stationary and non-impact load, the low-speed situations.


To improve the sliding performance and life of the bearing, bearing information should choose these factors into account. Bearings and bearing liner information collectively referred to as bearing materials, bearing wear and journal information, bearing their own materials, lubricants and lubrication directly related.