2014年9月16日星期二

flanged ball bearing

Show cross spiral line traces the emergence of such traces is mainly due to the bus straight wheel of existence, bump phenomenon, Double Row Ball Slewing Bearing when in grinding, the grinding wheel and the workpiece is only part of the contact, when the workpiece or the grinding wheel reciprocating motion after several times, cross spiral line and the naked eye reproduced on the workpiece performance will be observed. The helix pitch and workpiece speed, rotational speed of workpiece size, but also with the wheel axis and the guide rail is not parallel to the working table.
(a) the main reason for the formation of the spiral line
1 grinding wheel dressing is bad, not chamfered corner, without the use of cooling liquid dressing;
Track 2 table guide Other bearing lubrication oil too much, cause the work station floating;
3 machine tool accuracy is not good;
4 the grinding pressure and flanged ball bearing.
(two) with the formation of the spiral line
1.V guide not good rigidity, the grinding wheel edge offset, just contact with the work surface;
2 dressing noisy round table reversing speed is not stable, the precision is not high, the grinding wheel is a slightly less edge trimming;
The 3 workpiece itself poor rigidity;
4 wheel is broken too peeled off the sand and grinding of iron deposition in the grinding wheel on the surface, this should be trimmed worm gear speed reducer grinding wheel with cooling water rinse or wash clean;
5 wheel dressing is not good, local projection etc..
Analysis of causes of bearing grinding traces generated.

2014年9月14日星期日

high speed bearing Judgment bearing will use again

Judgment bearing will use again, to high speed bearing damage degree, the machine performance, importance, operating conditions, crane bearing such as checking cycle later decided. Check the results, if it is found that the bearing damage and abnormal situation, hurt a section to find out the reason, countermeasures. In addition, the inspection results, if there are some defects in it, the bearing can not be used, need to replace new bearing.
A. inner and outer ring, rolling body cage, in which any cracks and debris.
B. inner and outer ring, Single Row Ball Slewing Bearing rolling body which any split.
C. raceway, rib, rolling card significantly hurt.
D. retainer wear or loosen rivets.
E. raceway surface, rolling rust and bruises.
F. surface of rolling, rolling a significant indentation and trace.
A creep of G. inner diameter of surface or outer diameter.
H. thermal slewing rings discoloration.
I. grease sealed bearings seals and shields to serious damage.

2014年9月12日星期五

miniature ball bearings Analysis of deep groove ball bearing quality

 Compared with sliding bearing, deep groove ball bearing and miniature ball bearing, general conditions of deep groove ball bearing, the rolling Needle Roller Bearing efficiency and hydrodynamic bearing lubricated bearings, but a mixed lubrication bearing to the high number of;
1, ability to withstand the impact load is poor;
2, the radial clearance is relatively small, angular contact radial bearings can be preloaded available pretightening force to eliminate the clearance, high running precision; high speed heavy load bearing life is low;
3, for the same size of Thin section bearings the shaft diameter, bearing width smaller than the sliding bearing, the axial structure of machine is compact; vibration and noise;
4, most of the rolling bearing can be both radial and axial load, so the bearing assembly has the advantages of simple structure; the radial size than the sliding bearing;
5, the consumption of lubricant, which is convenient for sealing, easy maintenance;
6, do not need useful nonferrous linear ball bearing metal;
7, a high degree of standardization, mass production, low cost;

2014年9月8日星期一

flanged ball bearing matching precision bearing installation.

In order to improve the matching precision bearing installation, must use the measurement methods and tools do not make the flanged ball bearing deformation, high precision bearings precision measurement of bearing inner and outer circle with the surface size of the actual project, the measurement can be related to the inner and outer diameters of all be measured, and make a comprehensive analysis of the measured data, the according to precision bearings, matching with the shaft and hole of installation parts. The distribution of shaft and hole in the actual measurement of the corresponding size and geometry, temperature and measurement should be carried out in the bearing under the same.
To guarantee Taper roller bearings the higher actual tie effect, the shaft and hole matched with a bearing surface, the roughness should be as small as possible.
In the above measurement, should be in the outer circle and bearing inner hole, and the corresponding surface of the shaft and the seat hole, on both sides near the assembly chamfer, respectively two groups of marker can show the maximum deviation direction, so that in the actual assembly, the match two party of maximum deviation of the same orientation so, in the assembly, the deviation can be partially offset.
The purpose of making two sets of directional signs, is the deviation compensation can be considered, even supported at both ends of each rotating accuracy slewing bearing improved, and between the two bearing seat hole and the trunnion coaxiality error on both ends are partially eliminated. The mating surface to surface strengthening measures, such as sandblasting, precision plunger diameter slightly larger plug a hole, are beneficial to improve matching precision. 

2014年9月6日星期六

high speed bearing The sequential step bearing finishin

Bearing order superfinishing can generally be divided into three steps: cutting, cutting, semi finishing machining.
The first step: Bearing cutting
Convex peak surface conical bearing contact surface and rough rolling stone, due to a smaller contact area, a force per unit area is larger, in certain pressure, stone first by bearing workpiece "anti cutting" role, the stone surface of abrasive loss and fragmentation, showing some new sharp grinding grain and edge. At the same time, surface asperity bearing workpiece by fast cutting, the cutting and anti cutting to remove the bearing surface of the workpiece and the grinding affected layer of convex peak. This stage is called the cutting stage, at this stage most of removed metal allowance.
The second mobile crane bearing step: cutting bearing
As the process continues, bearing the workpiece surface has been polished. At this time, a contact with the workpiece surface area increased, the unit area pressure decreases, the cutting depth decreases, the cutting ability is abate. At the same time, hole stone surface is blocked, stone in the half cutting state. This stage is called semi cutting stage bearing finishing, half cutting stage cutting workpiece surface bearing traces of shallow, and the emergence of reali slim bearings dark luster.
The third step: the finishing stage
This is the last step in ultra precision machining of bearing. With the workpiece surface to be gradually removed, the contact area of stone and workpiece surface is further increased, and, stone and bearing surface gradually by the lubricating oil film isolation, the force per unit area is very small, the cutting effect decreases, then automatically stop cutting. At this stage we Series super thin section bearings call the finishing stage. The whole stage light surface workpiece without cutting mark, SKF bearing appears bright finished luster.

2014年9月4日星期四

miniature ball bearings comprehensive up the following main indicators

Working temperature: 1 by low temperature limit the lowest temperature of lubricating parts should be higher than the grease, otherwise it will increase the resistance of the highest temperature should be below the temperature limit; grease, wind power bearing otherwise it will lose because of grease lubrication capacity loss; the highest applicable temperature grease should be below the drop point 20 ~ 30 ℃.
2 speed: lubricating parts of the operation speed is higher, the shear stress of the lubricating grease is bigger, and the high speed dynamic mechanical temperature to rise quickly, easy to make the lubricant thinning and erosion, so we should select the consistency grease bigger.
3: according to the load miniature ball bearing load is the key to ensure the selection of grease lubrication, lubrication points taper roller bearing should be used for heavy load of base oil with high viscosity, thickened grease agent content is high; if can bear heavy load and shock load, should choose high extreme pressure and anti grinding grease resistance, such as the grease containing molybdenum disulfide.
4 conditions: environmental conditions refer to the work environment and the surrounding medium lubrication points, such as air humidity, dust and corrosive medium. In contact with water or damp environment condition, can choose the grease of water resistance. Such as calcium, lithium base; harsh conditions, should be used with grease and rust, but Angular contact ball bearings should not use sodium base grease water resistance is poor; in the lubrication points with strong chemical medium environment, should be chemical resistant selection of fluorine element grease; in the environment with more dust, grease containing graphite thick optional; to seal with special requirements, should use sodium base grease.
5 cost factors: in the selection of grease, but also consider the economic use, comprehensive analysis using this grease is extending the lubrication cycle, charging times, self aligning bearing fat consumption, bearing failure rate and repair cost.

2014年9月2日星期二

flanged ball bearing Bearing use and coordination The use of bearing

Use the matters needing attention
Rolling bearings make precision parts, and therefore requested the use of the corresponding support cautious attitude, not only Thin section bearings changing  flanged ball bearing high performance, if used improperly, can not achieve the expected performance, so, use of the bearing that should pay attention to the following items:
Keep the bearings and the surrounding environment clean. Even the eyes can not see the smile dirt into the bearing, also increase the bearing wear, vibration and noise.
Use the installation carefully, do not allow powerful punch, does not allow direct percussion bearing with a hammer, not allowed to pass through the Needle Roller Bearing rolling pressure.
Use tools appropriate, accurate, as far as possible the use of special tools, the use of fabric and fiber or something to avoid.
To prevent corrosion of bearings, the direct use of hands to take bearings, should wash hands sweat, and coated with high quality mineral oil before operation, during the rainy season and summer with particular attention to anti rust.
Bearings with
Coordination selection
Inner diameter and outer thin wall bearings diameter of rolling bearings are manufactured according to the standard tolerance, bearing inner ring and shaft, tolerance of outer ring and the seat hole degree can only through tolerance and seat hole control shaft neck to achieve. With the bearing inner ring and shaft using the basic hole system, combined with the outer ring of the bearing seat hole of the shaft.
The correct choice of cooperation, must know the actual load conditions of bearing, the working temperature and other requirements, but in fact it is very difficult. Therefore, in most cases it is used according to the selection of fine grinding.
The size of load
The ring and the shaft or housing between crossed roller bearings the win depends on the size of the load, heavy load by win larger, lighter load by winning the smaller amount.