Ball bearing screw is widely used in the dull top secret , but the difference between dull acceptance Ball is certainly not identical , Ka Machinery Co., Ltd. Nantong finishing difference in this ball of application areas :
Rotating Nut (R1) Series Ball : Semiconductor dull, dull industrial people , woodworking machines , laser processing machines, conveying devices.
Precision ground ball screws : CNC dull, Nanjing intermediate precision air conditioning vent thing machines, industrial dull , electronic dull, dull transportation , aerospace industry , the use of other antenna actuator , the valve switching devices.
Ball cap style : Fast handling system, as usual dull industrial automation dull.
Heavy Ball : All-electric injection molding machines, stamping machines, semiconductor manufacturing equipment , heavy-duty brakes, industrial dull , forging dull.
High DN value Ball : High-speed stuff , high-speed integrated processing center machine .
Rolled Ball Screws Level : low friction , smooth operation of the benefits and costs low while agile supply .
High-speed ball screw : CNC rigid , precision stuff machines, industrial dull, dull electronics , high-speed rigid.
2013年8月29日星期四
Ball bearing under way force status classification
Single push thrust bearings are mounted on the ends and ball screw preload . Can improve the axial stiffness of the ball bearing screw ; pre-stretching resettlement , preload large, so screw things only suffer tension. But the essentials of the screw placement is more sensitive to thermal deformation , while bearing life than double push - push-push low . Push- push-push one pair of ends mounted thrust bearing and radial ball bearings portfolio, the screw has a maximum stiffness , which can be used at both ends of the double bearing , thrust bearing and last radial ball bearings, and impose tight top force . The essentials appropriate for high rigidity , high speed, high precision , precision ball screw drive system . However, this arrangement can essentials thermal deformation of the screw into the thrust bearing preload , so plan requires increase the thrust bearing stiffness of the bearing ability and bracket . Double push a simply supported at one end mounted type thrust bearing , a second end attached to the ball bearings , axial stiffness is not too high ; ball out of the use of thermal deformation should be too small and the impact of resettlement should be too small to make heat and screw things when away from the common section at one end mounted thrust bearing , thrust bearing due to restrained thermal elongation and bred gap . pushing a freestyle thrust bearing mounted at one end and the other end unconnected. Its end is the free state, so carrying ability of small , low axial stiffness
2013年8月27日星期二
How to check the appearance of bearing
In the use of cross bearing, we first check the appearance of imported bearings, to determine whether it conforms to the standard we require. Here to share with everyone one that we should check that those parts. Bearings should be checked for astigmatism lamp, the appearance of the bearings, cracks and other parts of careful observation.
1, various mechanical injuries, such as rubs, scratches, bruised, bumps, etc., can cause adverse bearing installation, causing partial load and stress concentration, resulting in a decline in rotation accuracy and service life.
2, rust, black and pits, the latter two are easy to store moisture and dirt defects, the most likely to develop into rust. The corrosion is the cause poor installation, the sources of early wear and fatigue, severe corrosion cause bearing scrap.
3, various cracks, such as raw materials, crack, crack forging, heat treatment and grinding cracks, cracks, these cracks in the future during the operation of the bearing, will be a source of stress concentration and rapid expansion, resulting in rupture of the bearing of the bearing life and safety at work of great impact. In fact, for the important purpose bearings, bearing factory has 100% of its constituent parts or ray magnetic particle inspection.
4, peeling and folding, these two defective part and base metal binding is not strong, and its surroundings often exist to varying degrees, or depleted carbon decarburization phenomenon, materials easy caving, debossing or wear of the bearing life and accuracy are negative.
5, riveted or welded cage quality rivet head is mainly observed deviation, skew, relaxation, lack of meat or 'eyelid', the correct position of the welding, solder joint is too large or too small, whether strong or welding welding caused by excessive stuck rolling phenomenon more than a few that we focus on checking SKF bearings in part inspection, in addition to other than the part of the inspection, in addition to poor quality such as typing, such as illegible, damaged, shall be considered as defective, In severe cases, can not be accepted.
1, various mechanical injuries, such as rubs, scratches, bruised, bumps, etc., can cause adverse bearing installation, causing partial load and stress concentration, resulting in a decline in rotation accuracy and service life.
2, rust, black and pits, the latter two are easy to store moisture and dirt defects, the most likely to develop into rust. The corrosion is the cause poor installation, the sources of early wear and fatigue, severe corrosion cause bearing scrap.
3, various cracks, such as raw materials, crack, crack forging, heat treatment and grinding cracks, cracks, these cracks in the future during the operation of the bearing, will be a source of stress concentration and rapid expansion, resulting in rupture of the bearing of the bearing life and safety at work of great impact. In fact, for the important purpose bearings, bearing factory has 100% of its constituent parts or ray magnetic particle inspection.
4, peeling and folding, these two defective part and base metal binding is not strong, and its surroundings often exist to varying degrees, or depleted carbon decarburization phenomenon, materials easy caving, debossing or wear of the bearing life and accuracy are negative.
5, riveted or welded cage quality rivet head is mainly observed deviation, skew, relaxation, lack of meat or 'eyelid', the correct position of the welding, solder joint is too large or too small, whether strong or welding welding caused by excessive stuck rolling phenomenon more than a few that we focus on checking SKF bearings in part inspection, in addition to other than the part of the inspection, in addition to poor quality such as typing, such as illegible, damaged, shall be considered as defective, In severe cases, can not be accepted.
Requirements for machine tool spindle bearings
In the machine tool bearings, bearings is widely used. Spindle bearing with certain technical requirements. Introduce to you the following analysis
1 speed and temperature
With the development of science and technology, more and more high spindle speed, speed range and thus the greater the deep groove ball bearing high speed stability requirements are also increasing. Machine tool spindle bearing temperature is an important factor in limiting speed of the bearing. Under normal circumstances, the right choice bearing type, tolerance levels, configuration, clearance (preload) size, lubricants and lubrication, etc., to a certain extent, improve the speed performance of rolling bearings.
(2) carrying capacity and life
The general machine tool, the life of the main spindle assembly to maintain accuracy of the spindle is its period of use, therefore, required to maintain the accuracy bearing spindle assembly performance to meet life requirements. For heavy-duty machine tools or powerful cutting machine, you should first consider the bearing capacity.
3 stiffness and vibration resistance
To ensure the quality of the machining, the spindle system must have sufficient rigidity, otherwise it will have a greater re-mapping error even flutter. Vibration resistance refers to the forced vibration and self-excited vibration capability. Spindle assembly vibration resistance depends on the spindle and bearing stiffness and damping. Using the preload bearing can effectively increase the stiffness of the spindle system.
4 Noise
In high-speed grinder, the grinding noise and bearing noise is the main ingredient should be used in low-noise rolling bearings.
1 speed and temperature
With the development of science and technology, more and more high spindle speed, speed range and thus the greater the deep groove ball bearing high speed stability requirements are also increasing. Machine tool spindle bearing temperature is an important factor in limiting speed of the bearing. Under normal circumstances, the right choice bearing type, tolerance levels, configuration, clearance (preload) size, lubricants and lubrication, etc., to a certain extent, improve the speed performance of rolling bearings.
(2) carrying capacity and life
The general machine tool, the life of the main spindle assembly to maintain accuracy of the spindle is its period of use, therefore, required to maintain the accuracy bearing spindle assembly performance to meet life requirements. For heavy-duty machine tools or powerful cutting machine, you should first consider the bearing capacity.
3 stiffness and vibration resistance
To ensure the quality of the machining, the spindle system must have sufficient rigidity, otherwise it will have a greater re-mapping error even flutter. Vibration resistance refers to the forced vibration and self-excited vibration capability. Spindle assembly vibration resistance depends on the spindle and bearing stiffness and damping. Using the preload bearing can effectively increase the stiffness of the spindle system.
4 Noise
In high-speed grinder, the grinding noise and bearing noise is the main ingredient should be used in low-noise rolling bearings.
2013年8月24日星期六
Vibration bearing vibration group selection
Vibration bearings and plain bearings of the different characteristics
1, Appearance Features
Vibration bearings:
A. rolling diameter increased, the rolling body length increased.
B. outer rib cage guided by the roller, the roller to reduce the force.
C. Use of the inner wall to guide roller, roller improve functioning.
D. cylindrical roller bearing cage with the overall structure, strength greatly increased.
E. aligning bearing hole diameter tank design, lubrication effect.
Plain bearings:
A. roller bearing diameter and length of the rolling elements are small.
B. cage with rollers or inner guidance.
C. Cylindrical roller bearing cage using rivet structure, easy to loose, out cover.
D. aligning bearing no sump hole diameter, lubrication poor results.
2, the choice of materials
Vibration bearings:
A. inner and outer rings and rolling bearing steel vacuum degassing, good fatigue resistance.
B. cage aluminum manganese bronze material, high strength, good elasticity, abrasion resistance better.
Plain bearings:
A. inner and outer rings and rolling with common bearing steel.
B. cage made of zinc brass, low strength, poor flexibility.
3, heat treatment
Vibration bearings:
A. inner and outer rings using shell - Ma Ma mixed hardening or quenching and tempering, uniform hardness, internal stress; toughness, shock and vibration.
B. In the temperature less than 150C when working stability.
Plain bearings:
Inner and outer rings using ordinary quenching method, poor toughness, shock and vibration performance is poor, poor thermal stability.
4, tolerances and manufacturing process
Vibration bearings:
A. strict accordance with the P6 class precision manufacturing standards, especially in inner diameter tolerance is very small.
B. ball size ≤ 0.002 Difference
C. Cylindrical roller diameter of a convexity practice, to avoid stress concentration.
D. rolling surface ultra-precision processing, smooth finish.
Plain bearings:
A. General PO level precision tolerances (part P6 class standard) manufacturing.
B. rolling grouping ≤ 0.005.
C. Cylindrical Roller without convexity practice.
D. Part raceway only for polished finish low.
5, the internal clearance
Vibration bearings:
Clearance by mechanical vibration requirements of production, range control in a small range, and good consistency.
Plain bearings:
Clearance generally based on the standard group or group C3 production, clearance, or small, or range, discreteness.
6, using the results
Vibration bearings:
Low noise, low temperature rise, good stability, long life, no early fatigue.
Plain bearings:
Noise, temperature rise, stability is not good, life is short, there is the phenomenon of early fatigue.
Bearing vibration group selection
With the bearing manufacturing technology has improved continuously, reflecting the dynamic performance of the bearing vibration and noise are increasingly valued by the people. Users of the bearing vibration and noise awareness of the technical characteristics are also increasingly sensitive requirements are also increasing.
Bearing vibration refers to the geometric center of the bearing part is the instantaneous deviation from an ideal position moves, bearing parts with time-varying elastic deformation, and other rotary motion bearing all the movements necessary, known bearing vibration.
For a single bearing vibration testing, currently using two units of measurement. One for Acceleration, which is measured in decibels (dB), category code Z1, Z2, Z3; another type of speed, which is measured in microns / second (um / s), group codenamed ZV1 , ZV2, ZV3. These flags bearing vibration group bearing the supplementary code into basic code on the right.
Bearing vibration and noise are closely related, because the vibration source of the noise, the noise is vibration characterization, so in bearing manufacturing and testing process, through strict control of the bearing vibration value targets, to achieve the purpose of bearing noise control.
In the choice of bearing vibration constituencies, must be based on the specific use of the bearing conditions. If the host for smooth operation have special requirements, you should choose more appropriate bearing vibration group to meet and achieve the smooth operation of its provisions, such as machine tool spindles. Of the bearing vibration and noise are a requirement, such as cars and aircraft, the same should be used in the corresponding bearing vibration groups in order to achieve the requirements. The noise of the bearing with special requirements, such as electric fans and some other appliances should be used with low noise bearings, in order to meet the requirements.
The main factors affecting bearing vibration
By the bearing structural design parameters determined by stiffness, flexibility, quality, and damping vibration system constituted under the operating conditions will produce adapt to its mechanical vibrations.
Manufacturing process of the deviation caused by vibration, the smaller the deviation, vibration is smaller. Surface of the ball roundness, waviness, surface roughness of the bearing part of the most influential factor of vibration, followed by the inner and outer shape of the channel error and surface roughness, cleanliness and again is the bearing lubricant quality.
Operating conditions, such as installation conditions, speed, direction of the axial load borne by, for money.
1, Appearance Features
Vibration bearings:
A. rolling diameter increased, the rolling body length increased.
B. outer rib cage guided by the roller, the roller to reduce the force.
C. Use of the inner wall to guide roller, roller improve functioning.
D. cylindrical roller bearing cage with the overall structure, strength greatly increased.
E. aligning bearing hole diameter tank design, lubrication effect.
Plain bearings:
A. roller bearing diameter and length of the rolling elements are small.
B. cage with rollers or inner guidance.
C. Cylindrical roller bearing cage using rivet structure, easy to loose, out cover.
D. aligning bearing no sump hole diameter, lubrication poor results.
2, the choice of materials
Vibration bearings:
A. inner and outer rings and rolling bearing steel vacuum degassing, good fatigue resistance.
B. cage aluminum manganese bronze material, high strength, good elasticity, abrasion resistance better.
Plain bearings:
A. inner and outer rings and rolling with common bearing steel.
B. cage made of zinc brass, low strength, poor flexibility.
3, heat treatment
Vibration bearings:
A. inner and outer rings using shell - Ma Ma mixed hardening or quenching and tempering, uniform hardness, internal stress; toughness, shock and vibration.
B. In the temperature less than 150C when working stability.
Plain bearings:
Inner and outer rings using ordinary quenching method, poor toughness, shock and vibration performance is poor, poor thermal stability.
4, tolerances and manufacturing process
Vibration bearings:
A. strict accordance with the P6 class precision manufacturing standards, especially in inner diameter tolerance is very small.
B. ball size ≤ 0.002 Difference
C. Cylindrical roller diameter of a convexity practice, to avoid stress concentration.
D. rolling surface ultra-precision processing, smooth finish.
Plain bearings:
A. General PO level precision tolerances (part P6 class standard) manufacturing.
B. rolling grouping ≤ 0.005.
C. Cylindrical Roller without convexity practice.
D. Part raceway only for polished finish low.
5, the internal clearance
Vibration bearings:
Clearance by mechanical vibration requirements of production, range control in a small range, and good consistency.
Plain bearings:
Clearance generally based on the standard group or group C3 production, clearance, or small, or range, discreteness.
6, using the results
Vibration bearings:
Low noise, low temperature rise, good stability, long life, no early fatigue.
Plain bearings:
Noise, temperature rise, stability is not good, life is short, there is the phenomenon of early fatigue.
Bearing vibration group selection
With the bearing manufacturing technology has improved continuously, reflecting the dynamic performance of the bearing vibration and noise are increasingly valued by the people. Users of the bearing vibration and noise awareness of the technical characteristics are also increasingly sensitive requirements are also increasing.
Bearing vibration refers to the geometric center of the bearing part is the instantaneous deviation from an ideal position moves, bearing parts with time-varying elastic deformation, and other rotary motion bearing all the movements necessary, known bearing vibration.
For a single bearing vibration testing, currently using two units of measurement. One for Acceleration, which is measured in decibels (dB), category code Z1, Z2, Z3; another type of speed, which is measured in microns / second (um / s), group codenamed ZV1 , ZV2, ZV3. These flags bearing vibration group bearing the supplementary code into basic code on the right.
Bearing vibration and noise are closely related, because the vibration source of the noise, the noise is vibration characterization, so in bearing manufacturing and testing process, through strict control of the bearing vibration value targets, to achieve the purpose of bearing noise control.
In the choice of bearing vibration constituencies, must be based on the specific use of the bearing conditions. If the host for smooth operation have special requirements, you should choose more appropriate bearing vibration group to meet and achieve the smooth operation of its provisions, such as machine tool spindles. Of the bearing vibration and noise are a requirement, such as cars and aircraft, the same should be used in the corresponding bearing vibration groups in order to achieve the requirements. The noise of the bearing with special requirements, such as electric fans and some other appliances should be used with low noise bearings, in order to meet the requirements.
The main factors affecting bearing vibration
By the bearing structural design parameters determined by stiffness, flexibility, quality, and damping vibration system constituted under the operating conditions will produce adapt to its mechanical vibrations.
Manufacturing process of the deviation caused by vibration, the smaller the deviation, vibration is smaller. Surface of the ball roundness, waviness, surface roughness of the bearing part of the most influential factor of vibration, followed by the inner and outer shape of the channel error and surface roughness, cleanliness and again is the bearing lubricant quality.
Operating conditions, such as installation conditions, speed, direction of the axial load borne by, for money.
High-speed bearings during installation and fit issues to consider when
A high speed bearings fit and clearance according to both the high-speed bearing requirements, but also according to temperature bearing requirements, so consider the coordination and clearance to take account of the following points:
(1) when the temperature rose to high temperature dimensional change and hardness;
(2) high speed, the centrifugal force caused by the force system change and shape change.
In short, high-speed, high-temperature conditions, coordination and clearance from the choice of motor bearings should strive to maintain the accuracy and performance.
In order to ensure the bearing raceway after installation of small deformation, interference fit amount of interference can not get too big, and high speed centrifugal force and high temperature thermal expansion, or offset with the surface normal pressure. Or so with the surface relaxation, so the amount of interference must be considered under the premise of these two factors to be carefully calculated, at room temperature under constant speed and effective amount of interference for high-speed bearings may be invalid.
In considering the high speed motor bearing clearance only to consider the above factors, but also to consider the axis thermal expansion effects on the bearing clearance, bearing in working condition requires that there is at operating temperature optimum clearance, and this clearance is taken into account, the outer ring ball groove center precise alignment of state formation. As high-speed bearings for lower relative sliding and internal friction, it is best not to use the inner and outer rings relative axial displacement method to adjust the ball bearing clearance.
In considering the amount of interference with the bearing and clearance, to note that materials at high temperatures becomes soft and easily deformed features, as well as many from the room temperature to high temperature changes cause some permanent deformation possibilities.
(2) the requirement for host-related parts
Where high-speed rotary motor bearings bearing system requires precision dynamic balancing shaft and the bearing seat hole installation site should have a higher than normal requirements of dimensional accuracy and geometrical precision, especially for concentricity and retaining shoulder seat hole or journal the vertical, and in consideration of these issues, it must also be noted that the high-speed operation of the bearing elements and high-temperature factor.
(1) when the temperature rose to high temperature dimensional change and hardness;
(2) high speed, the centrifugal force caused by the force system change and shape change.
In short, high-speed, high-temperature conditions, coordination and clearance from the choice of motor bearings should strive to maintain the accuracy and performance.
In order to ensure the bearing raceway after installation of small deformation, interference fit amount of interference can not get too big, and high speed centrifugal force and high temperature thermal expansion, or offset with the surface normal pressure. Or so with the surface relaxation, so the amount of interference must be considered under the premise of these two factors to be carefully calculated, at room temperature under constant speed and effective amount of interference for high-speed bearings may be invalid.
In considering the high speed motor bearing clearance only to consider the above factors, but also to consider the axis thermal expansion effects on the bearing clearance, bearing in working condition requires that there is at operating temperature optimum clearance, and this clearance is taken into account, the outer ring ball groove center precise alignment of state formation. As high-speed bearings for lower relative sliding and internal friction, it is best not to use the inner and outer rings relative axial displacement method to adjust the ball bearing clearance.
In considering the amount of interference with the bearing and clearance, to note that materials at high temperatures becomes soft and easily deformed features, as well as many from the room temperature to high temperature changes cause some permanent deformation possibilities.
(2) the requirement for host-related parts
Where high-speed rotary motor bearings bearing system requires precision dynamic balancing shaft and the bearing seat hole installation site should have a higher than normal requirements of dimensional accuracy and geometrical precision, especially for concentricity and retaining shoulder seat hole or journal the vertical, and in consideration of these issues, it must also be noted that the high-speed operation of the bearing elements and high-temperature factor.
2013年8月23日星期五
Crossed roller bearings isolation block design defects and improvement
Crossed roller bearings known as cross roller bearings, cylindrical roller generally use roller or tapered roller in a single raceway cross mutually arranged between the roller and the roller cage or through isolation block interval, with high rotational accuracy, the larger the capacity, the smaller dimensions and a higher rotational speed and rigidity, with a very wide range of uses.
cross roller bearing design flaws and improve it.
1 inside the bearing arrangement of the roller, two adjacent rollers arranged in cross, all arranged in the same direction roller intersects the centerline axis of the rotary bearing, two rollers arranged in a direction opposite to the axis of intersection of the center line of the bearing slewing relative to the plane of the center roller symmetrical.
2 Isolation of existing designs of the defect blocks according to the current design, two cylindrical grooves spacers axis the axis perpendicular to the radial plane spacers are parallel, and in that the projection plane perpendicular to each other. Manufactured using current design method has the advantage of an isolation block with good versatility. As long as the selection of different roller bearing the same specifications, generally can use the same kind of isolation blocks. Spacers is cylindrical, its axis center line tangent to the circle of rollers. However, two adjacent roller axes A and B blocks are not isolated from the axis perpendicular to the radial plane are parallel.
Prime line roller work surface and isolation block cylindrical groove surface pixel lines are not parallel, but inclined at an angle, causing the contact state is not good, affect the bearing rotation flexibility and precision rotation speed is higher, the effect is also more obvious. Therefore, it is necessary to improve the design of the separators, the separators of the roller axis of the cylindrical grooves parallel to the axis, thereby improving the isolation block the cylindrical roller groove surface. The higher the speed, the more obvious the effect.
cross roller bearing design flaws and improve it.
1 inside the bearing arrangement of the roller, two adjacent rollers arranged in cross, all arranged in the same direction roller intersects the centerline axis of the rotary bearing, two rollers arranged in a direction opposite to the axis of intersection of the center line of the bearing slewing relative to the plane of the center roller symmetrical.
2 Isolation of existing designs of the defect blocks according to the current design, two cylindrical grooves spacers axis the axis perpendicular to the radial plane spacers are parallel, and in that the projection plane perpendicular to each other. Manufactured using current design method has the advantage of an isolation block with good versatility. As long as the selection of different roller bearing the same specifications, generally can use the same kind of isolation blocks. Spacers is cylindrical, its axis center line tangent to the circle of rollers. However, two adjacent roller axes A and B blocks are not isolated from the axis perpendicular to the radial plane are parallel.
Prime line roller work surface and isolation block cylindrical groove surface pixel lines are not parallel, but inclined at an angle, causing the contact state is not good, affect the bearing rotation flexibility and precision rotation speed is higher, the effect is also more obvious. Therefore, it is necessary to improve the design of the separators, the separators of the roller axis of the cylindrical grooves parallel to the axis, thereby improving the isolation block the cylindrical roller groove surface. The higher the speed, the more obvious the effect.
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