In order to ensure satisfactory performance , needle roller / angular contact ball bearings like all ball bearings and roller bearings , must always bear acting on the radial and Angular contact ball bearing axial certain minimum load , especially if they want to run at high speed or subjected to high accelerations or rapid changes in the load direction . Under these conditions , the rolling element and the inertia force of the retainer and lubricants friction bearing arrangement may play a deleterious effect on the rolling conditions , and may cause the rolling element and the raceway between the sliding destructive .
Increase in radial needle bearing on the necessary minimum radial load can be estimated using the following formula :
Frm = 0.02 C
Angular contact ball bearings necessary Deep groove ball bearing minimum axial load can be calculated using the following formula :
Where
Frm = minimum radial load, kN
Fam = minimum axial load, kN
C = basic dynamic load rating ( see product table ) , kN
C0 = basic static load rating ( see product table ) , kN
dm = bearing mean diameter
= 0,5 (d + D), mm
n = rotational speed, r / min
Cold start or lubricant viscosity is very high, even demanding loads. Bearing weight of the components together with external forces generally exceed the minimum necessary load. If this is not the case, you must give Needle roller / angular contact ball bearings impose additional radial and / or axial loads.
2013年11月17日星期日
2013年8月22日星期四
Ball bearing vibration and noise reduction technology to improve its process equipment
At present, China deep groove ball bearing and seal products advanced internal structure parameters are almost identical, but such products in China vibration and noise levels are very different with foreign products, mainly in the manufacturing and working conditions factors. From the bearing industry point of view, condition factor can be solved reasonably requested by the host, and how to reduce the vibration caused by the manufacturer and the noise factor is the bearing industry must be addressed.
Many domestic and experiments show that: cage, ring, ball bearing vibration processing quality for different degrees of impact, where the processing quality ball bearing vibration impact on the most obvious, followed by processing quality rings, the most important influence factors and the ferrule ball roundness, waviness, roughness, surface bump and other injuries.
Ball products of the most prominent problem is the discrete vibration large, severe surface defects (single point, cluster points, pits, etc.), although the surface roughness, size, shape, the error level is not lower than the outside of the circle, but the co-sets After the bearing vibration value is high, and even produce different sound, the main problem is the waviness no control (no standards, no suitable test and analysis equipment), with an indication of poor vibration machine, grinding wheel, grinding disc, coolant, process parameters are problematic ; the other hand to improve the management level, to avoid the bump wounds, scratches, burns and other machines of any quality problems.
For the rings, the most serious impact of bearing vibration is channel waviness and surface roughness. For example, small and medium deep groove ball bearing inner channel roundness greater than 2μm, the bearing vibration will have a significant impact, both inside and outside the channel waviness greater than 0.7μm, the bearing vibration value increases with the waviness of the channel serious gouges Vibration can rise more than 4dB, and even different sound.
Both balls or rings, waviness produced in the grinding, although Superfinishing waviness can improve and reduce roughness, but the most fundamental measure is to reduce the ultra-fine grinding process of waviness, to avoid randomness bump hurt, there are two main measures:
First, reduce the rolling surface vibration when ultra-fine grinding, get a good surface finish shape accuracy and surface texture quality in order to reduce vibration, grinding super machine must have good vibration resistance, bed and other important structural parts with vibration absorption, ultra- Whetstone fine machine oscillating system has a good anti-vibration performance; improve grinding speed, grinding abroad commonly used outer raceway 6202 60,000 spindle, grinding speed 60m / s or more, domestic general much lower, mainly due to the spindle and main bearing performance limitations. In high-speed grinding, grinding force is small, thin grinding deterioration is not easy to burn, and can improve the precision and efficiency, low noise ball bearing great influence; spindle stiffness and movement speed characteristics of the low-noise ball bearing a great influence on the grinding vibration, the higher the stiffness, grinding speed on the grinding force change, the less sensitive to vibration grinding system smaller; improve spindle bearing support stiffness, random balancing technology to improve the grinding spindle vibration sex. Foreign grinding vibration velocity (eg Gamfior) is approximately one-tenth of the domestic general spindle; improve cutting and grinding wheel dressing Whetstone quality is essential. China's current wheel Whetstone main problem is poor uniformity organizational structure, seriously affecting the ultra-low-noise ball bearing grinding machining quality; sufficiently cooled, improve filtering accuracy; improve the feed to the system fine resolution, reduce the feed inertia; reasonable wear ultra-processing process parameters and machining processes are factors that can not be ignored, grinding amount to small, strictly geometric tolerance, small diameter ball bearings should not use Superfinishing, coarse grinding super not be separated to ensure good surface quality.
Second is to improve machining plane precision grinding and superfinishing process reduces error reflection of the outer end face grinding and super positioning reference during processing. The channel diameter ultra-fine error reflection on the ditch by OD grinding, grinding on the ditch ditch super error reflection indirect transitive. If the workpiece in the transfer process produces bump injury, will be directly mapped to the raceway complex machined surface, the impact of bearing vibration. So you must take the following measures: improve the positioning reference surface shape accuracy; processing passes smoothly and without a bump hurt; rough allowance form and position errors can not be too large, especially in the remaining amount is small, too large error will cause the final grinding and ultra-fine close to the final shape accuracy has not improved the quality requirements, seriously affecting the processing quality consistency.
Many domestic and experiments show that: cage, ring, ball bearing vibration processing quality for different degrees of impact, where the processing quality ball bearing vibration impact on the most obvious, followed by processing quality rings, the most important influence factors and the ferrule ball roundness, waviness, roughness, surface bump and other injuries.
Ball products of the most prominent problem is the discrete vibration large, severe surface defects (single point, cluster points, pits, etc.), although the surface roughness, size, shape, the error level is not lower than the outside of the circle, but the co-sets After the bearing vibration value is high, and even produce different sound, the main problem is the waviness no control (no standards, no suitable test and analysis equipment), with an indication of poor vibration machine, grinding wheel, grinding disc, coolant, process parameters are problematic ; the other hand to improve the management level, to avoid the bump wounds, scratches, burns and other machines of any quality problems.
For the rings, the most serious impact of bearing vibration is channel waviness and surface roughness. For example, small and medium deep groove ball bearing inner channel roundness greater than 2μm, the bearing vibration will have a significant impact, both inside and outside the channel waviness greater than 0.7μm, the bearing vibration value increases with the waviness of the channel serious gouges Vibration can rise more than 4dB, and even different sound.
Both balls or rings, waviness produced in the grinding, although Superfinishing waviness can improve and reduce roughness, but the most fundamental measure is to reduce the ultra-fine grinding process of waviness, to avoid randomness bump hurt, there are two main measures:
First, reduce the rolling surface vibration when ultra-fine grinding, get a good surface finish shape accuracy and surface texture quality in order to reduce vibration, grinding super machine must have good vibration resistance, bed and other important structural parts with vibration absorption, ultra- Whetstone fine machine oscillating system has a good anti-vibration performance; improve grinding speed, grinding abroad commonly used outer raceway 6202 60,000 spindle, grinding speed 60m / s or more, domestic general much lower, mainly due to the spindle and main bearing performance limitations. In high-speed grinding, grinding force is small, thin grinding deterioration is not easy to burn, and can improve the precision and efficiency, low noise ball bearing great influence; spindle stiffness and movement speed characteristics of the low-noise ball bearing a great influence on the grinding vibration, the higher the stiffness, grinding speed on the grinding force change, the less sensitive to vibration grinding system smaller; improve spindle bearing support stiffness, random balancing technology to improve the grinding spindle vibration sex. Foreign grinding vibration velocity (eg Gamfior) is approximately one-tenth of the domestic general spindle; improve cutting and grinding wheel dressing Whetstone quality is essential. China's current wheel Whetstone main problem is poor uniformity organizational structure, seriously affecting the ultra-low-noise ball bearing grinding machining quality; sufficiently cooled, improve filtering accuracy; improve the feed to the system fine resolution, reduce the feed inertia; reasonable wear ultra-processing process parameters and machining processes are factors that can not be ignored, grinding amount to small, strictly geometric tolerance, small diameter ball bearings should not use Superfinishing, coarse grinding super not be separated to ensure good surface quality.
Second is to improve machining plane precision grinding and superfinishing process reduces error reflection of the outer end face grinding and super positioning reference during processing. The channel diameter ultra-fine error reflection on the ditch by OD grinding, grinding on the ditch ditch super error reflection indirect transitive. If the workpiece in the transfer process produces bump injury, will be directly mapped to the raceway complex machined surface, the impact of bearing vibration. So you must take the following measures: improve the positioning reference surface shape accuracy; processing passes smoothly and without a bump hurt; rough allowance form and position errors can not be too large, especially in the remaining amount is small, too large error will cause the final grinding and ultra-fine close to the final shape accuracy has not improved the quality requirements, seriously affecting the processing quality consistency.
2013年8月17日星期六
Deep groove ball bearing vibration noise root causes
Deep groove ball bearing vibration and noise on the formation mechanism of domestic and international aspects of the control of vibration and noise, there are two different approaches. Bearing vibration mainly from two sources:
One bearing bearing caused by external incentives inherent vibration, referring to the bearing inner ring, outer ring, rolling elements and cage the natural vibration.
Two deep groove ball bearing due to contact between moving parts forced vibration caused by collision, such as ball rolling is not an ideal sphere, inside and outside the channel contact point trajectory is not a perfect circle (roundness, waviness), the raceway not the ideal smooth surface (roughness) and the rolling elements and cage in motion collision and lubricants in the forced vibration caused by impurities, vibration and sound are closely related, but slightly different sense, That is the sound originated in vibration, acoustic vibrations in the air is transmitted to humans by the feeling of hearing, so the ultra-high frequency vibrations are inaudible. However, if the receiver and the sound vibration characteristics of the receiver is the same, two received signals received relevant to the whole, according to this view, controlling vibration or noise control can play the same effect. And because the vibration control is simple, so home and abroad priority control vibration to ensure product quality. Therefore, for the general bearing, it is recommended to concentrate its limited human and financial resources to do a good job of bearing vibration control. Quality standards should not separate the noise, of course, according to foreign experience for a special bearing products, such as computer hard drives, CD recorder drive system bearings, vibration assessment is not easy to use, can develop criteria to assess noise measurement method .
One bearing bearing caused by external incentives inherent vibration, referring to the bearing inner ring, outer ring, rolling elements and cage the natural vibration.
Two deep groove ball bearing due to contact between moving parts forced vibration caused by collision, such as ball rolling is not an ideal sphere, inside and outside the channel contact point trajectory is not a perfect circle (roundness, waviness), the raceway not the ideal smooth surface (roughness) and the rolling elements and cage in motion collision and lubricants in the forced vibration caused by impurities, vibration and sound are closely related, but slightly different sense, That is the sound originated in vibration, acoustic vibrations in the air is transmitted to humans by the feeling of hearing, so the ultra-high frequency vibrations are inaudible. However, if the receiver and the sound vibration characteristics of the receiver is the same, two received signals received relevant to the whole, according to this view, controlling vibration or noise control can play the same effect. And because the vibration control is simple, so home and abroad priority control vibration to ensure product quality. Therefore, for the general bearing, it is recommended to concentrate its limited human and financial resources to do a good job of bearing vibration control. Quality standards should not separate the noise, of course, according to foreign experience for a special bearing products, such as computer hard drives, CD recorder drive system bearings, vibration assessment is not easy to use, can develop criteria to assess noise measurement method .
Seal type deep groove ball bearings
Many deep groove ball bearing sealing problems mainly ineffective drain grease and dust, etc., in a nutshell is poor sealing performance; non-contact seals no big problem, the main problem is multi-contact seals. What are the causes it?
Main bearing seal structure is relatively backward. Seal structure lies in the rotary member of the seal groove and the sealing cap sealing lips. Sealed general there are three forms, one does not actually slot; second is a small inner diameter, there is a step; third is a complete seal groove.
Sealing lip with a single and double lip of the points, to improve the sealing effect, we believe that the sealing lips should be developed and groove seal structure, because this form of contact seals and labyrinth seals combined sealing effect is better, but the process is complicated, higher cost.
In the modern enterprise in the pursuit of cost-premise, as far as possible the pursuit of double lip seal and groove seal structure deep groove ball bearings, but conditions were not under seal structure can only produce a general, after all, is now a large domestic use part of the sealing structure in general, and the sealing structure by many users.
Main bearing seal structure is relatively backward. Seal structure lies in the rotary member of the seal groove and the sealing cap sealing lips. Sealed general there are three forms, one does not actually slot; second is a small inner diameter, there is a step; third is a complete seal groove.
Sealing lip with a single and double lip of the points, to improve the sealing effect, we believe that the sealing lips should be developed and groove seal structure, because this form of contact seals and labyrinth seals combined sealing effect is better, but the process is complicated, higher cost.
In the modern enterprise in the pursuit of cost-premise, as far as possible the pursuit of double lip seal and groove seal structure deep groove ball bearings, but conditions were not under seal structure can only produce a general, after all, is now a large domestic use part of the sealing structure in general, and the sealing structure by many users.
2013年8月9日星期五
Causing deep groove ball bearing temperature causes and countermeasures
Typically, if used correctly deep groove ball bearings, can be used to its maximum life so far. If not used correctly will have an unexpected injury prematurely. And fatigue life of this relatively early damage, malfunction or accident we call quality use limit. Multiple causes for installation, use, lubrication on the non-standard, or other foreign matter from outside intrusion.
Deep groove ball bearing damage on the state, such as: bearing rings, ribs card injury, mainly due to lack of lubricant, not suitable for oil discharge structure defects, the intrusion of foreign bodies, bearing misalignment, shaft deflections is too large, or both the above reasons.
Therefore, only the investigation bearing damage, injury is difficult to know the real reason. However, if you know the bearing using mechanical, conditions of use, bearing the surrounding structure, to understand the situation before and after the accident, combined with state of the bearing damage, and several reasons, we can prevent similar incidents from recurring.
deep groove ball bearing vibration of the bearing damage is very sensitive, such as peeling, dents, rust, cracks, wear, etc. will be in rolling bearing vibration measurement reflected, therefore, through the use of special bearing vibration measurements (frequency analyzer, etc.) can be measure the size of the vibration, can not be inferred by the frequency of abnormal circumstances. The measured values due to the conditions of use of rolling bearings or sensor installation location is different, so each machine needs prior to analysis and comparison of the measured values determined criteria.
Deep groove ball bearing temperature, generally room temperature outside of the bearing can be inferred, it can be measured directly using the hole bearing outer ring temperature, which is more accurately measured.
Typically, the temperature of rolling bearing operation began to rise slowly as 1-2 hours after reaching steady state. The normal temperature because of the machine bearing the heat capacity, heat capacity, speed and load are different. If lubrication, improper installation, the bearing temperatures will soar, there will be high, then you must stop running, check the disassembly repair. Conditional thermal sensor can be used at any time to monitor the bearing operating temperature, and to achieve the temperature exceeds a predetermined value or when the alarm automatically stops running to prevent burning shaft accidents.
Deep groove ball bearing damage on the state, such as: bearing rings, ribs card injury, mainly due to lack of lubricant, not suitable for oil discharge structure defects, the intrusion of foreign bodies, bearing misalignment, shaft deflections is too large, or both the above reasons.
Therefore, only the investigation bearing damage, injury is difficult to know the real reason. However, if you know the bearing using mechanical, conditions of use, bearing the surrounding structure, to understand the situation before and after the accident, combined with state of the bearing damage, and several reasons, we can prevent similar incidents from recurring.
deep groove ball bearing vibration of the bearing damage is very sensitive, such as peeling, dents, rust, cracks, wear, etc. will be in rolling bearing vibration measurement reflected, therefore, through the use of special bearing vibration measurements (frequency analyzer, etc.) can be measure the size of the vibration, can not be inferred by the frequency of abnormal circumstances. The measured values due to the conditions of use of rolling bearings or sensor installation location is different, so each machine needs prior to analysis and comparison of the measured values determined criteria.
Deep groove ball bearing temperature, generally room temperature outside of the bearing can be inferred, it can be measured directly using the hole bearing outer ring temperature, which is more accurately measured.
Typically, the temperature of rolling bearing operation began to rise slowly as 1-2 hours after reaching steady state. The normal temperature because of the machine bearing the heat capacity, heat capacity, speed and load are different. If lubrication, improper installation, the bearing temperatures will soar, there will be high, then you must stop running, check the disassembly repair. Conditional thermal sensor can be used at any time to monitor the bearing operating temperature, and to achieve the temperature exceeds a predetermined value or when the alarm automatically stops running to prevent burning shaft accidents.
Sealed deep groove ball bearings with grease on one side only
We use the process of deep groove ball bearing, bearing seals occasionally pry open the lid, this time we will find that while there is some bearing full of grease, while the other side there is no grease; while some bearing on both sides evenly fat distribution, especially the high price of the bearing, this is what causes it?
We know that the bearing during operation is the need to grease and rust, especially sealed deep groove ball bearings, grease the bearing can not be high-speed operation, will greatly shortened life expectancy. The bearing in the production process is a process up to a, the bearing inner ring and the balls, the cage is assembled, the first thing is to wash, rinse after the pressure side of the seal cover, and then flip over bearing, plus fat (Average plus the bearing interior volume is 30% ~ 35%), and then a cover.
Here we found, sealed deep groove ball bearing with one side in the production process are not added fat, grease applied to only one side only; if both sides, then add oil, bearing the manufacturing process, the more of a process, so the production efficiency will be reduced.
At this time someone will ask, why would some bearing grease on both sides of it? If the bearing grease seals on both sides, this one is the price is relatively high, and the other is used over the bearing. Why do you say? This is the high price of bearings are generally better quality, this is the result of deep groove ball bearing side full inspection, and that is to go through the rotating bearing test, after the rotation bearing grease on the inside of a uniform distribution; another is bearing After using, used, oil will certainly be evenly distributed.
So says the new deep groove ball bearings with grease on both sides of only one side while the other side is not normal, users do not worry, just take a few turns bearings, or turn a few minutes to get the machinery above, bearing grease on the inside of the uniform rotation , do not affect the use.
We know that the bearing during operation is the need to grease and rust, especially sealed deep groove ball bearings, grease the bearing can not be high-speed operation, will greatly shortened life expectancy. The bearing in the production process is a process up to a, the bearing inner ring and the balls, the cage is assembled, the first thing is to wash, rinse after the pressure side of the seal cover, and then flip over bearing, plus fat (Average plus the bearing interior volume is 30% ~ 35%), and then a cover.
Here we found, sealed deep groove ball bearing with one side in the production process are not added fat, grease applied to only one side only; if both sides, then add oil, bearing the manufacturing process, the more of a process, so the production efficiency will be reduced.
At this time someone will ask, why would some bearing grease on both sides of it? If the bearing grease seals on both sides, this one is the price is relatively high, and the other is used over the bearing. Why do you say? This is the high price of bearings are generally better quality, this is the result of deep groove ball bearing side full inspection, and that is to go through the rotating bearing test, after the rotation bearing grease on the inside of a uniform distribution; another is bearing After using, used, oil will certainly be evenly distributed.
So says the new deep groove ball bearings with grease on both sides of only one side while the other side is not normal, users do not worry, just take a few turns bearings, or turn a few minutes to get the machinery above, bearing grease on the inside of the uniform rotation , do not affect the use.
2013年7月10日星期三
Quality check bearing operation tips
Bearings should be checked after installation, you should ensure that the bearing in place, rotating flexible cable wiring, improper installation, such as bearings, bearing temperature will rise quickly and damage, and even death card bearing fracture or other serious accidents.
First, the rotation of the bearing sounds with a stethoscope and other tests, there is a strong metal noise, abnormal sound, irregular sound, etc. Exceptions. The reasons are poor lubrication, shaft or bearing bad precision, bearing damage, foreign invasion and so on.
Secondly, bearing temperature, and can be based on speculation bearing the external temperature. But the use of direct measurement of the bearing outer ring hole temperature is more accurate. Bearing temperature gradually increased from the start of operation, typically 1 to 2 hours after the temperature to stabilize. If the bearing bad installation, the temperature will soar, abnormal high temperature. The reason such as too much lubricant, bearing clearance is too small, poor installation, seal friction and too big. The case of high-speed rotation, the bearing structure, the choice of lubrication is the cause of the error.
Third, small machinery can be rotated by hand to verify rotate smoothly. Check the project due to nick, indentation caused by dysfunctional, because poor installation, mount the torque generated by poor processing unstable, because clearance is too small, the installation error, seal friction torque caused by too large and so on. Without exception, you can begin powering.
Fourth, the large machinery can not be manually rotated so cut off the power immediately after starting load, machine idle to check for vibration, noise, etc. in contact with the rotating member is to confirm no abnormality, into the power running.
First, the rotation of the bearing sounds with a stethoscope and other tests, there is a strong metal noise, abnormal sound, irregular sound, etc. Exceptions. The reasons are poor lubrication, shaft or bearing bad precision, bearing damage, foreign invasion and so on.
Secondly, bearing temperature, and can be based on speculation bearing the external temperature. But the use of direct measurement of the bearing outer ring hole temperature is more accurate. Bearing temperature gradually increased from the start of operation, typically 1 to 2 hours after the temperature to stabilize. If the bearing bad installation, the temperature will soar, abnormal high temperature. The reason such as too much lubricant, bearing clearance is too small, poor installation, seal friction and too big. The case of high-speed rotation, the bearing structure, the choice of lubrication is the cause of the error.
Third, small machinery can be rotated by hand to verify rotate smoothly. Check the project due to nick, indentation caused by dysfunctional, because poor installation, mount the torque generated by poor processing unstable, because clearance is too small, the installation error, seal friction torque caused by too large and so on. Without exception, you can begin powering.
Fourth, the large machinery can not be manually rotated so cut off the power immediately after starting load, machine idle to check for vibration, noise, etc. in contact with the rotating member is to confirm no abnormality, into the power running.
订阅：
博文 (Atom)