In the dry process cement production line process, the raw material has been widely used roller press, and has made considerable economic and social benefits, a significant increase of its energy-saving effect is also recognized by the majority of manufacturers to use. But in the course of its use, the bearing life is short, damage and replacement process cycle is long, costly, labor-intensive, but it restricts the normal operation of the rotary kiln.
My company put into operation by the end of 2012 the two 4500t / d clinker production line, run until June 2003, four sets of Chengdu Lijun Industrial Co., Ltd. manufactured CLF180-120 there have been varying degrees of roller presses the problem of high bearing temperatures, 7 mid-May the 2nd roll maneuver near the gear side roller bearing damage. Total running time of 2041 hours, the service life of less than three months.
First, the device pre-operational status
Roller press run early roller bearing temperature between 50-60 degrees, there is no abnormal noise, bearing grease used by the U.S. Castrol brand Molub-Alloy 777-2 ES model roller presses grease, the amount of fuel in strict accordance with equipment manufacturers Requests the Executive. Five to six months, there have been several cycles of water blockage, resulting in bearing temperature up to 70 degrees. In mid-June, and found that the lower part of the inner bearing oil outlet circulating water discharge phenomenon occurs suspected side of the bearing end cap rupture caused by cooling water, then turn off the inside of the circulating water, the new grease replenishing the oil discharged into the roller press production. In early July, roller presses the bearing temperature has been hovering around 55 degrees to 75 degrees, for various reasons during the roller press is always open to open the stop, there have been more than 24 hours continuously feeding situation. July 10 start, roller press repeatedly appear continuous feeding more than four hours on account of the temperature exceeds 75 degrees to stop jumping. July 12 greaser checking the oil discharge roller press discovered the bearing fragments. Determine the bearing roller press has been damaged. Since the roller press has been put into the roll gap deviation, pressure instability. Deviation due to the roll gap gauge, pressure gauge, the width of the roll gap and other factors frequently exceeds the limit mediation, there have been almost no more than 48 hours continuously feeding situation.
Second, the disintegration of the investigation bearing damage
After the demolition of the roller press gearbox bearing cap open and found that there is a rift bearing outside diameter, a broken ball bearings, inner and outer diameter with five out of crack, the bearing inner and outer raceway badly worn bearing retainer wear . Bearing cap surrounded by circulating water cooling on both sides have two brass compression fracture phenomena, round copper tubes are flattened, leading to fracture, width of about 100mm. Check the other side of the roll maneuver roller bearings, intact, the bearing clearance of 0.75mm, within the normal range.
Third, bearing damage cause analysis and improvement
1 First, bearing life is too short not to troubleshoot and manufacturer of quality bearing assembly itself, but should also work with bearing operating conditions in harsh environments and have a great relationship.
2. Bearing thermal design flaws. Such a large bearing operating process will produce a lot of frictional heat, so that both sides of the bearing cap manufacturer designed circulating path, the heat generated by the bearing grease and the case conduction through the cooling copper tube absorbs heat water circulating outflow apparatus body, lower bearing temperatures. But it cooled copper mounting position is unreasonable, bearing swing too easy to squeeze into the brass, brass deformation caused by blockage, fracture, loss of cooling effect. To avoid copper tube is extruded, only increase the gap between the copper and the bearing, to ensure a greater swing bearing free space, which requires manufacturers to redesign, production bearing cap or another design a cooling device.
3 brass water lead to rupture of the rear bearing lubrication failure, it could be this short bearing life is an important factor. Equipment inspection work found during the inspections bearing lower discharge port has water leakage, immediately made a report, but this is not possible in the cooling copper pipe break after the first time discovered. Since the bearing inner brass cap by squeezing fracture, circulating water entering the bearing, destroyed the environment lubrication, the bearing balls and the raceway serious friction generates a lot of heat, bearing balls and the diameter of each component such damage.
4 brass frequent clogging cooling and design too small, poor cooling effect also affect bearing life. Cooled copper diameter is too small, the circulating water and debris clog adhesion brass scale deposition in the roller press often occurs during operation bearing high temperature, inlet and outlet brass examination revealed multiple blockage, affecting the cooling effect, the final installed at the inlet Y-strainer before easing clogging.
5 roller presses the material into the inadequate control of particle size, diameter 200mm super chunk too, long nip large deviations, corrective frequently lead to bearing overload and shorten the service life. Initial production mining crushing, crushing machine safety door is not well controlled, resulting in more than 150mm above the individual particle size of limestone blocks into the next process, clogging the feed opening roller press, leading to uneven feeding, causing the roll gap large deviations, and even lead roll sewing too large equipment mediation. Granularity than 100mm rigid material frequently enters roller presses, roller presses squeeze in an instant when all the large reaction force bearing on the bearing itself, the life of the bearing caused a fundamental impact. Improved granularity of limestone, sandstone and clay crusher materials and faulty phase continued up to more than two months, no broken, large water through the bypass feed materials into the roller press feeding system, more than 250mm above the chunk size is almost Each class appears stuck roll gap, resulting in the roll gap width gauge mediation. This is the roller press operation there have been no more than six months more than 48 hours continuously feeding the root cause.
6 There is no steady flow positions periodically removed materials, excluding enrichment metal, so that the device frequently overloaded mediation affect bearing life. Material into the roller press is impossible to avoid the presence of metal objects and accumulation roller presses the original width of the roll gap of about 20mm, 70mm roll gap will exceed the overload relief, less than 50mm metal objects will only increase the roll surface wear, greater than 50mm size metal objects or materials into the roller press is too large, it will cause the rollers instantly generate excessive impact force, resulting in the roll gap than 70mm, the pressure exceeds 15MPa, exceeds the bearing load limits, the control system will suddenly roller press release pressure or mediation. Especially metal roller presses will cycle loop in the roller press greatest harm. So they requested that must be periodically clearing, clearing accumulated in the roller press metal objects within the system, reduce or avoid damage to equipment, particularly bearing.
7 hidden when the hydraulic system is now hidden, long-term bias is serious roll gap. As the hydraulic system problems, often lower than the pressure roller presses the side of the working pressure, both sides of the roll gap large deviation hydraulic pump long-term frequent correction, resulting in roller presses the bearing operating conditions poor, heavy load, the service life is reduced.
Fourth, the late running Precautions
Roller press bearing life is short, equipment failure rate is the current cement industry a common problem, through analysis of the above reasons, the production process management is a top priority, as long as control the granularity of the material into the roller press, regularly scheduled clearance, reducing metal roller presses against the probability of overload damage to the bearings, excluding hydraulic system problems, eliminating the long-term bias roll gap phenomenon, problem solving partial cutting, take care of the bearing uniform force. As long as the above points, improving the operating environment of the equipment, the equipment can operate normally, to extend the life of each part, in order to improve the operation rate.
2013年8月27日星期二
Rolling residual magnetism technical conditions
Truck crane telescopic cylinder piston rod (pole) grinding waste-prone, according to our experience, the following measures to prevent waste.
1 piece of each point carefully measuring the amount of remaining mill
Should be based on the workpiece bending, deflection, dislocation and other data to determine whether the depth marks grinding.
(1) for grinding of not more than 0.50mm left the site operator can carefully measure the deflection, bending, dislocation, marks and other values. Leaving less than 0.20mm for grinding workpieces must consult the staff agreed before grinding.
(2) If the amount of deflection or bending amount exceeding one third of the parts to wear straightening after grinding.
(3) measuring the diameter of dislocation sites on both sides of both sides of the deflection data and the data available at the mill minimum diameter maximum value minus the yaw yaw position value, the amount of the difference is the actual grinding. Such as: dislocation at the grinding capacity of the smallest diameter 0.40mm, maximum deflection part of the deflection is 0.30mm, the actual grinding capacity equal to 0.40-0.30 = 0.10mm, grinding capacity is small, it is likely appear in the grinding burn conditions, resulting in waste.
(4) marks the site of deep, roll bearings grinding rasp the former is best to use local symmetry points (the most serious side parts) filed a two symmetrical facets, by filing off the site measured. If the measured diameter minus the diameter of marks after less than 0.20mm, should consult before grinding.
(2) properly handle grinding burns
(A) before grinding grinding according to the above requirements can be checked, if the coarse grinding sparks big, there are local burns, while after two reciprocating grinding burn site can not be eliminated, it should be carried out once the workpiece deflection values measurements. If the deflection values ??were lower than the preceding grinding limit, should be straightened. By straightening still not eliminated, must be scrapped.
(2) grinding sparks should pay attention to the changes, once burned, the workpiece Serve waste. Special minor burns, if measured yaw values ??below one-third of the amount of grinding, you can continue grinding; than one-third of which should be scrapped.
Burn causes and the wheel model, the workpiece material is also a relationship. Preventive measures are timely repair wheel, adjust the amount of feed (coarse or fine grinding, if the feed rate is too small will produce minor burns), add enough coolant and adjust the workpiece and wheel speed.
3 Carefully observe the spark
Once the grinding sparks too large to immediately retract. After all coarse grinding sparks phenomenon should not be interrupted, if the deflection off the fire area exceeds the amount of a quarter mill, to be straightened. Each wheel sparks near the ends of the workpiece gradually increased, the top should be checked whether the temperature is too high, if the top temperature is consistent with the workpiece to be tight at the top end. If the spark through bays larger, it indicates that the site of the top bracket is unreasonable, so that it temperature. Grinding sparks should not exist when the elephant stopped, if a serious fire off what should be measured yaw and grinding capacity, when the amount of deflection over a quarter mill grind it up.
4. Strictly control the quality and accuracy of processing
The spot diameter measured values ??are inconsistent, brackets and tailstock respond timely adjustments.
(1) through coarse, semi-fine grinding, the workpiece is not cylindrical tolerance. If ovality tolerance of the parts of a broken fire phenomenon, should be measured yaw value, if this value exceeds 30μm should try again after straightening mill; After several feed grinding, in total more than 50μm feed when Sparks will no longer off the fire, measured ovality should be zero; when measured ellipticity still exceeds tolerance, you should try again after grinding wheel dressing, if the ellipse is still not eliminated, the top hole should be checked for damage, research injuries ( At this point the workpiece surface showing polygonal).
(2) the surface after grinding and finishing the reasons presented Duoleng measures: If wheel has been blunt, should be trimmed; wheel if there is noticeable vibration, balance should be adjusted; head frame, motor frame vibration isolation facilities have been damaged, shall be repaired ; excessive vibration if the workpiece itself, should be properly deceleration; top too tight or too loose, it should be adjusted.
(3) If the coarse surface occurs when a large spiral, the reason is bad dresser, grinding wheel dressing time must be uniform and must not have significant single angle spark phenomenon blunt surface after grinding wheel prone to large spiral.
(4) grinding, the workpiece often appear galling, scratched and dirty coolant phenomenon. To prevent this phenomenon, the new wheel should be finishing with a wire brush a few times (pay attention to safety).
(5) When grinding the workpiece phenomenon taper, drum, saddle-shaped, both ends of a diameter larger or smaller, you should adjust the bracket, tailstock, wheel overrun and the number of workpieces at both ends of the workpiece and the grinding wheel travel time.
5 strictly controlled two top parts of the temperature
According to two top temperature changes are reasonable judgment leading tightness; generally top temperature slightly higher than the temperature of the workpiece as the standard.
(A) two leading causes of high temperatures: First, the top too tight, two center hole is top notch and the workpiece misalignment. If the top is too tight, first loosen the top, add the butter on the two center hole and then adjust the tightness of the top.
(2) If there is a top temperature is too high, then the top center hole with the workpiece misalignment.
(3) When the temperature of the top two consistent temperature of the workpiece, the workpiece two polygonal phenomenon does not occur, and more uniform spark, this time to continue the grinding. As part two phenomena appear Duoleng, you should look at the top tight, if the workpiece does not burn, you can wear them all. When the workpiece two spark uneven, they will bear about the top end.
1 piece of each point carefully measuring the amount of remaining mill
Should be based on the workpiece bending, deflection, dislocation and other data to determine whether the depth marks grinding.
(1) for grinding of not more than 0.50mm left the site operator can carefully measure the deflection, bending, dislocation, marks and other values. Leaving less than 0.20mm for grinding workpieces must consult the staff agreed before grinding.
(2) If the amount of deflection or bending amount exceeding one third of the parts to wear straightening after grinding.
(3) measuring the diameter of dislocation sites on both sides of both sides of the deflection data and the data available at the mill minimum diameter maximum value minus the yaw yaw position value, the amount of the difference is the actual grinding. Such as: dislocation at the grinding capacity of the smallest diameter 0.40mm, maximum deflection part of the deflection is 0.30mm, the actual grinding capacity equal to 0.40-0.30 = 0.10mm, grinding capacity is small, it is likely appear in the grinding burn conditions, resulting in waste.
(4) marks the site of deep, roll bearings grinding rasp the former is best to use local symmetry points (the most serious side parts) filed a two symmetrical facets, by filing off the site measured. If the measured diameter minus the diameter of marks after less than 0.20mm, should consult before grinding.
(2) properly handle grinding burns
(A) before grinding grinding according to the above requirements can be checked, if the coarse grinding sparks big, there are local burns, while after two reciprocating grinding burn site can not be eliminated, it should be carried out once the workpiece deflection values measurements. If the deflection values ??were lower than the preceding grinding limit, should be straightened. By straightening still not eliminated, must be scrapped.
(2) grinding sparks should pay attention to the changes, once burned, the workpiece Serve waste. Special minor burns, if measured yaw values ??below one-third of the amount of grinding, you can continue grinding; than one-third of which should be scrapped.
Burn causes and the wheel model, the workpiece material is also a relationship. Preventive measures are timely repair wheel, adjust the amount of feed (coarse or fine grinding, if the feed rate is too small will produce minor burns), add enough coolant and adjust the workpiece and wheel speed.
3 Carefully observe the spark
Once the grinding sparks too large to immediately retract. After all coarse grinding sparks phenomenon should not be interrupted, if the deflection off the fire area exceeds the amount of a quarter mill, to be straightened. Each wheel sparks near the ends of the workpiece gradually increased, the top should be checked whether the temperature is too high, if the top temperature is consistent with the workpiece to be tight at the top end. If the spark through bays larger, it indicates that the site of the top bracket is unreasonable, so that it temperature. Grinding sparks should not exist when the elephant stopped, if a serious fire off what should be measured yaw and grinding capacity, when the amount of deflection over a quarter mill grind it up.
4. Strictly control the quality and accuracy of processing
The spot diameter measured values ??are inconsistent, brackets and tailstock respond timely adjustments.
(1) through coarse, semi-fine grinding, the workpiece is not cylindrical tolerance. If ovality tolerance of the parts of a broken fire phenomenon, should be measured yaw value, if this value exceeds 30μm should try again after straightening mill; After several feed grinding, in total more than 50μm feed when Sparks will no longer off the fire, measured ovality should be zero; when measured ellipticity still exceeds tolerance, you should try again after grinding wheel dressing, if the ellipse is still not eliminated, the top hole should be checked for damage, research injuries ( At this point the workpiece surface showing polygonal).
(2) the surface after grinding and finishing the reasons presented Duoleng measures: If wheel has been blunt, should be trimmed; wheel if there is noticeable vibration, balance should be adjusted; head frame, motor frame vibration isolation facilities have been damaged, shall be repaired ; excessive vibration if the workpiece itself, should be properly deceleration; top too tight or too loose, it should be adjusted.
(3) If the coarse surface occurs when a large spiral, the reason is bad dresser, grinding wheel dressing time must be uniform and must not have significant single angle spark phenomenon blunt surface after grinding wheel prone to large spiral.
(4) grinding, the workpiece often appear galling, scratched and dirty coolant phenomenon. To prevent this phenomenon, the new wheel should be finishing with a wire brush a few times (pay attention to safety).
(5) When grinding the workpiece phenomenon taper, drum, saddle-shaped, both ends of a diameter larger or smaller, you should adjust the bracket, tailstock, wheel overrun and the number of workpieces at both ends of the workpiece and the grinding wheel travel time.
5 strictly controlled two top parts of the temperature
According to two top temperature changes are reasonable judgment leading tightness; generally top temperature slightly higher than the temperature of the workpiece as the standard.
(A) two leading causes of high temperatures: First, the top too tight, two center hole is top notch and the workpiece misalignment. If the top is too tight, first loosen the top, add the butter on the two center hole and then adjust the tightness of the top.
(2) If there is a top temperature is too high, then the top center hole with the workpiece misalignment.
(3) When the temperature of the top two consistent temperature of the workpiece, the workpiece two polygonal phenomenon does not occur, and more uniform spark, this time to continue the grinding. As part two phenomena appear Duoleng, you should look at the top tight, if the workpiece does not burn, you can wear them all. When the workpiece two spark uneven, they will bear about the top end.
2013年8月24日星期六
Bearing after the heat treatment quality problems often
A soft spot
Because insufficient heating and cooling is bad, improper operation and other causes hardening of the bearing surface of the part of the phenomenon known locally insufficient hardness quenching soft spots. It is the same as the surface decarburization can cause surface wear resistance and fatigue strength in serious decline.
Roller bearing parts in the quenching process due to the formation of stress cracks called quenching cracks. Cause such cracks reasons: because the quenching temperature is too high or too fast cooling, thermal stress and metal mass volume change when the stress fracture resistance than steel; work surface defects original (such as surface micro-cracks or draw marks) or steel internal defects (such as slag, severe non-metallic inclusions, white point, residual shrinkage, etc.) at a stress concentration quenching; severe surface decarburization and carbide segregation; parts after quenching and tempering insufficient or timely tempering; previous process caused by too much stress cold punching, forging folding, turning deep marks, oil, sharp edges, etc. ditch. Quenching cracks deep and slender, straight fracture, fracture surface without oxidation colors. The organization is characterized by quenching cracks no cracks on both sides of decarburization phenomenon, the obvious difference with forging cracks and material cracks. In short, resulting in quenching cracks may be due to one or more of these factors, the existence of internal stress cracks forming the main hardening. It is often in the bearing rings on the straight longitudinal cracks or ring cracking; ball bearing on the shape of the S-shaped, T-shaped or ring.
Second, due to heat
Three, overheating
Fourth, quenching cracks
Bearing parts in the heat treatment process, if it is heated in an oxidizing medium, the surface oxidation occurs to parts of the surface carbon content reduced, resulting in surface decarburization. Determination of surface decarburization depth available in metallographic examination and microhardness metallographic method. Surface decarburization depth over the last machining allowance will make parts scrapped. In the surface layer microhardness distribution curve measurement prevail, do arbitration criterion.
Five, surface decarburization
Six, heat deformation
Quenching temperature is low or poor cooling in the microstructure produced more than the standard prescribed troostite organization called due to heat tissue, which decrease in hardness, wear resistance drastically reduced, affecting bearing life.
Bearing parts during heat treatment, the presence of thermal stress and stress, this stress can be superimposed on each other, or partially offset, is complex, because it along with the heating temperature, heating rate, cooling, cooling rate, part shape and the size of the change, so the heat distortion is inevitable. Understand and grasp its variation can make the bearing part of the deformation (such as elliptical rings, rose and large size) placed controllable range, is conducive to the production of conduct. Of course, during the heat treatment the mechanical collision of parts also cause deformation, but this deformation can be used to reduce and improve operations avoided.
Port from the bearing part can be observed on the rough microstructure after hardening overheating. But to determine the exact extent of overheating must observe the microstructure. If GCr15 steel hardened tissues appear coarse acicular martensite, was quenched overheating tissue. Even cause serious overheating quenching cracks. As quenching overheated steel coarse crystals, may cause parts of the decrease in toughness, impact resistance decreased, the bearing life is reduced. Overheating tissues residual austenite increases, dimension stability decreased. Formation may be due to the quenching temperature is too high or too long causing heat insulation comprehensive overheating; also may be due to the original organization carbon ribbon severe in the two areas with the formation of carbon between the local martensite needles thick, caused by local overheating.
Several bearing the above heat treatment process recurrent problem, which directly affect the quality of the bearing, so that the production process of the bearing, should try to avoid such a situation.
Because insufficient heating and cooling is bad, improper operation and other causes hardening of the bearing surface of the part of the phenomenon known locally insufficient hardness quenching soft spots. It is the same as the surface decarburization can cause surface wear resistance and fatigue strength in serious decline.
Roller bearing parts in the quenching process due to the formation of stress cracks called quenching cracks. Cause such cracks reasons: because the quenching temperature is too high or too fast cooling, thermal stress and metal mass volume change when the stress fracture resistance than steel; work surface defects original (such as surface micro-cracks or draw marks) or steel internal defects (such as slag, severe non-metallic inclusions, white point, residual shrinkage, etc.) at a stress concentration quenching; severe surface decarburization and carbide segregation; parts after quenching and tempering insufficient or timely tempering; previous process caused by too much stress cold punching, forging folding, turning deep marks, oil, sharp edges, etc. ditch. Quenching cracks deep and slender, straight fracture, fracture surface without oxidation colors. The organization is characterized by quenching cracks no cracks on both sides of decarburization phenomenon, the obvious difference with forging cracks and material cracks. In short, resulting in quenching cracks may be due to one or more of these factors, the existence of internal stress cracks forming the main hardening. It is often in the bearing rings on the straight longitudinal cracks or ring cracking; ball bearing on the shape of the S-shaped, T-shaped or ring.
Second, due to heat
Three, overheating
Fourth, quenching cracks
Bearing parts in the heat treatment process, if it is heated in an oxidizing medium, the surface oxidation occurs to parts of the surface carbon content reduced, resulting in surface decarburization. Determination of surface decarburization depth available in metallographic examination and microhardness metallographic method. Surface decarburization depth over the last machining allowance will make parts scrapped. In the surface layer microhardness distribution curve measurement prevail, do arbitration criterion.
Five, surface decarburization
Six, heat deformation
Quenching temperature is low or poor cooling in the microstructure produced more than the standard prescribed troostite organization called due to heat tissue, which decrease in hardness, wear resistance drastically reduced, affecting bearing life.
Bearing parts during heat treatment, the presence of thermal stress and stress, this stress can be superimposed on each other, or partially offset, is complex, because it along with the heating temperature, heating rate, cooling, cooling rate, part shape and the size of the change, so the heat distortion is inevitable. Understand and grasp its variation can make the bearing part of the deformation (such as elliptical rings, rose and large size) placed controllable range, is conducive to the production of conduct. Of course, during the heat treatment the mechanical collision of parts also cause deformation, but this deformation can be used to reduce and improve operations avoided.
Port from the bearing part can be observed on the rough microstructure after hardening overheating. But to determine the exact extent of overheating must observe the microstructure. If GCr15 steel hardened tissues appear coarse acicular martensite, was quenched overheating tissue. Even cause serious overheating quenching cracks. As quenching overheated steel coarse crystals, may cause parts of the decrease in toughness, impact resistance decreased, the bearing life is reduced. Overheating tissues residual austenite increases, dimension stability decreased. Formation may be due to the quenching temperature is too high or too long causing heat insulation comprehensive overheating; also may be due to the original organization carbon ribbon severe in the two areas with the formation of carbon between the local martensite needles thick, caused by local overheating.
Several bearing the above heat treatment process recurrent problem, which directly affect the quality of the bearing, so that the production process of the bearing, should try to avoid such a situation.
Bearing grinding process and requirements
Bearing in precision grinding, the rough demanding working surface of the grinding traces are often observed with the naked eye the surface of the grinding marks are the following:
Bearing surfaces are crossed spiral traces traces happen mainly due to poor wheel of the bus straight, there is uneven phenomenon, grinding, grinding wheel and the workpiece is only partial contact bearing, when the workpiece or wheel back and forth several times after exercise , the performance will be reproduced in the workpiece and the cross-helix can be observed visually. The pitch of the helix and the workpiece table speed, the size of workpiece speed, but also with the wheel axis is not parallel to the guide lines and the table.
(A) The main reason for the formation of helix
1 Dresser bad, not chamfered corners, unused coolant to be trimmed;
2 table guide rail lubricant too much, resulting workbench floating;
3 machine precision is not good;
4 grinding pressure is too big.
(B) forming the bearing surfaces having the spiral cause
1.V shaped rail rigidity bad, when an offset grinding wheel, but wheel edge in contact with the work surface;
2 noisy wheel dressing table commutation speed is unstable, accuracy is not high, so that the edge of a grinding wheel dressing slightly less;
3. Workpiece itself rigidity;
4 wheel has broken too flaking grit and the workpiece grinding wheel under the iron plot attached to the surface, this should be a good dressing wheel with cooling water wash or scrub clean;
5 wheel dressing well, there are local projections and so on.
Surface appears scaly scaly surface reproduces the main reason is due to traces of grinding wheel cutting edge is not sharp enough, in the grinding occurs when "eating to live" phenomenon, when large vibration.
Resulting in surface appears scaly traces of the specific reasons are:
A grinding wheel surface litter and oil thing;
2 Wheel untrimmed round;
3 wheel blunt. Dressing sharp enough;
4 fastening frame is not solid diamond, diamond or diamond quality is bad not shake sharp;
5 Wheel hardness uneven.
Face nap nap surface reproduces the main reason is due to traces of coarse grains shed, grain sandwiched between the workpiece and the grinding wheel and cause.
Workpiece surface grinding was napping in the specific reasons are:
1 coarse grinding traces left behind, grinding when not worn;
2 coolant coarse grains and tiny grains filter is not clean;
3 coarse abrasive wheel just trimmed off easily when;
4 toughness validity or grinding wheel is too soft;
5 abrasive workpiece material toughness with toughness and improper.
Have a direct bearing surface waveform traces we milled workpiece cut a cross-section perpendicular axis line and zoom, you can see the surrounding approximately sinusoidal. So that the center line along the axis of rotation without translation, the track is the sine waveform around the cylinder, which is also known as a polygon. Generating direct wave because the wheel moves relative to the workpiece or the grinding wheel on the workpiece by cyclically changing pressure and vibration caused by the exigencies. This vibration may be forced vibration, it may be self-excited vibration, thus directly on the workpiece often more than one wave frequency.
Direct waveform traces generated specific reasons are:
A grinding wheel spindle gap is too large;
2 Wheel hardness is too high;
3 wheel static balance wheel well or dull;
4. Workpiece speed is too high;
5 infeed is too big;
6 wheel spindle bearing wear, the gap is too large, resulting runout;
7 wheel or bench pressing means "crawl" and so on.
Surface of the workpiece surface reproduction burns often during grinding burns, burns there are several types, one burns machining direction along the wheel, dark black patches; Second, was the line or intermittent line shape.
Workpiece surface grinding process of being burned, summed up in the following reasons:
1 wheel too hard or too fine granularity tissue too dense;
(2) Feed excessive cutting fluid supply, cooling conditions are poor;
3. Workpiece speed is too low, wheel speed too fast;
4 wheel runout is too large, constantly changing due to grinding depth and burn;
5 dresser dressing is not timely or bad;
6 diamond sharp dresser bad;
7. Workpiece coarse grinding burns too deep, grinding allowance is too small, no worn;
8 Workpiece clamping force or suction deficiencies in the grinding force, the workpiece stops phenomenon exists.
Then the workpiece surface in the grinding process of how to know if it works burned? This is accomplished by periodic acid to check it out.
Workpiece after pickling, the surface is wet, should immediately astigmatism lamp visual inspection, the normal surface was uniformly dark gray. If so software point, showing dark clouds like black spots, and the entire perimeter uncertain; if decarbonization, is rendered dark gray or black piebald; if grinding cracks, the crack was cracked like, yes burns, one surface along Wheel machining direction showing dark black plaques, two lines are present or intermittent lines like. If the grinding process in the burn-in phenomenon, must promptly analyze the causes and take effective measures to solve them, to eliminate bulk burns.
Mainly the surface roughness of the surface roughness of the bearing parts are standard and process requirements, but in the processing and ultra-fine grinding process, for various reasons, often less than the specified requirements.
Mainly the surface roughness caused mainly due to:
1 grinding speed is too low, too fast feed rate, feed excessive, no feed grinding time is too short;
2. Workpiece speed is too high or the workpiece axis and the wheel axis vibration is too large;
3 wheel size is too coarse or too soft;
4 wheel dresser too fast or trimming mechanism gap is too large;
5 diamond wheel dressing is not sharp or of poor quality;
6 ultra-fine oil stone quality is not good, the installation location is not correct;
7 ultra-precision quality is mainly kerosene;
8 ultra-precise time is too short.
deep groove ball bearing in the grinding process, the work surface is achieved by high-speed rotation of the grinding wheel, grinding so if you do not follow the operating instructions for operation and adjust the device, it will work in the bearing surface of various defects, which affects The overall quality of the bearing.
Bearing surfaces are crossed spiral traces traces happen mainly due to poor wheel of the bus straight, there is uneven phenomenon, grinding, grinding wheel and the workpiece is only partial contact bearing, when the workpiece or wheel back and forth several times after exercise , the performance will be reproduced in the workpiece and the cross-helix can be observed visually. The pitch of the helix and the workpiece table speed, the size of workpiece speed, but also with the wheel axis is not parallel to the guide lines and the table.
(A) The main reason for the formation of helix
1 Dresser bad, not chamfered corners, unused coolant to be trimmed;
2 table guide rail lubricant too much, resulting workbench floating;
3 machine precision is not good;
4 grinding pressure is too big.
(B) forming the bearing surfaces having the spiral cause
1.V shaped rail rigidity bad, when an offset grinding wheel, but wheel edge in contact with the work surface;
2 noisy wheel dressing table commutation speed is unstable, accuracy is not high, so that the edge of a grinding wheel dressing slightly less;
3. Workpiece itself rigidity;
4 wheel has broken too flaking grit and the workpiece grinding wheel under the iron plot attached to the surface, this should be a good dressing wheel with cooling water wash or scrub clean;
5 wheel dressing well, there are local projections and so on.
Surface appears scaly scaly surface reproduces the main reason is due to traces of grinding wheel cutting edge is not sharp enough, in the grinding occurs when "eating to live" phenomenon, when large vibration.
Resulting in surface appears scaly traces of the specific reasons are:
A grinding wheel surface litter and oil thing;
2 Wheel untrimmed round;
3 wheel blunt. Dressing sharp enough;
4 fastening frame is not solid diamond, diamond or diamond quality is bad not shake sharp;
5 Wheel hardness uneven.
Face nap nap surface reproduces the main reason is due to traces of coarse grains shed, grain sandwiched between the workpiece and the grinding wheel and cause.
Workpiece surface grinding was napping in the specific reasons are:
1 coarse grinding traces left behind, grinding when not worn;
2 coolant coarse grains and tiny grains filter is not clean;
3 coarse abrasive wheel just trimmed off easily when;
4 toughness validity or grinding wheel is too soft;
5 abrasive workpiece material toughness with toughness and improper.
Have a direct bearing surface waveform traces we milled workpiece cut a cross-section perpendicular axis line and zoom, you can see the surrounding approximately sinusoidal. So that the center line along the axis of rotation without translation, the track is the sine waveform around the cylinder, which is also known as a polygon. Generating direct wave because the wheel moves relative to the workpiece or the grinding wheel on the workpiece by cyclically changing pressure and vibration caused by the exigencies. This vibration may be forced vibration, it may be self-excited vibration, thus directly on the workpiece often more than one wave frequency.
Direct waveform traces generated specific reasons are:
A grinding wheel spindle gap is too large;
2 Wheel hardness is too high;
3 wheel static balance wheel well or dull;
4. Workpiece speed is too high;
5 infeed is too big;
6 wheel spindle bearing wear, the gap is too large, resulting runout;
7 wheel or bench pressing means "crawl" and so on.
Surface of the workpiece surface reproduction burns often during grinding burns, burns there are several types, one burns machining direction along the wheel, dark black patches; Second, was the line or intermittent line shape.
Workpiece surface grinding process of being burned, summed up in the following reasons:
1 wheel too hard or too fine granularity tissue too dense;
(2) Feed excessive cutting fluid supply, cooling conditions are poor;
3. Workpiece speed is too low, wheel speed too fast;
4 wheel runout is too large, constantly changing due to grinding depth and burn;
5 dresser dressing is not timely or bad;
6 diamond sharp dresser bad;
7. Workpiece coarse grinding burns too deep, grinding allowance is too small, no worn;
8 Workpiece clamping force or suction deficiencies in the grinding force, the workpiece stops phenomenon exists.
Then the workpiece surface in the grinding process of how to know if it works burned? This is accomplished by periodic acid to check it out.
Workpiece after pickling, the surface is wet, should immediately astigmatism lamp visual inspection, the normal surface was uniformly dark gray. If so software point, showing dark clouds like black spots, and the entire perimeter uncertain; if decarbonization, is rendered dark gray or black piebald; if grinding cracks, the crack was cracked like, yes burns, one surface along Wheel machining direction showing dark black plaques, two lines are present or intermittent lines like. If the grinding process in the burn-in phenomenon, must promptly analyze the causes and take effective measures to solve them, to eliminate bulk burns.
Mainly the surface roughness of the surface roughness of the bearing parts are standard and process requirements, but in the processing and ultra-fine grinding process, for various reasons, often less than the specified requirements.
Mainly the surface roughness caused mainly due to:
1 grinding speed is too low, too fast feed rate, feed excessive, no feed grinding time is too short;
2. Workpiece speed is too high or the workpiece axis and the wheel axis vibration is too large;
3 wheel size is too coarse or too soft;
4 wheel dresser too fast or trimming mechanism gap is too large;
5 diamond wheel dressing is not sharp or of poor quality;
6 ultra-fine oil stone quality is not good, the installation location is not correct;
7 ultra-precision quality is mainly kerosene;
8 ultra-precise time is too short.
deep groove ball bearing in the grinding process, the work surface is achieved by high-speed rotation of the grinding wheel, grinding so if you do not follow the operating instructions for operation and adjust the device, it will work in the bearing surface of various defects, which affects The overall quality of the bearing.
2013年8月23日星期五
Oil-bearing support bearing assembly rotating
Oil-bearing assembly of the supporting shaft. Its rings and rolling elements are precision machined. Bearing in the factory, in order to protect the surface of the raceways and rolling elements are not corroded, in between the raceways and rolling elements into a rust grease oil or rust.
Bearings should be cleaned before installation. With anti-rust oil sealed bearing directly available gasoline or kerosene cleaning; thick oil or grease rust rust charged shall, light mineral oil, such as 10 # transformer oil heating oil or fat will melt cooled, then gasoline or kerosene to clean. Sides with shields or seals bearing grease at the factory joined, so when you do not have to clean install. Coated with anti-rust lubricant oil dual IKO cross roller bearings, the installation also without cleaning. In cleaning the installation process, should prevent foreign matter falling into the bearings, the result of slight abrasive will cause between the rolling element and raceway wear, increased noise and vibration.
Oil-bearing assembly and disassembly, mainly through two ways. First, the interference rings onto the shaft or pressed into the bearing hole; First, by heating up a large diameter bearing it, or cooling the bearing outer diameter narrowing it will be easily mounted on the shaft bearing seat or push hole. When pressurized mode, mechanical force or fluid pressure through a dedicated device will force acts directly on the assembly and disassembly of the seat ring, and never allow loading and unloading of force pass through the rolling. Otherwise it will cause the surface of the raceway and rolling elements indentation, resulting in increased noise and vibration damage. If a heating or cooling means for detachably, the heating temperature should be strictly controlled or cooling temperatures. Because the strength of the bearing surface microstructure by the structure of the metal surface, the temperature is too high will cause the tempering effect; temperature was too low will cause embrittlement of the metal surface. Typically the heating temperature does not exceed 100 ℃, the cooling must not end at the lowest temperature of minus 50 ℃. Also to be considered to be uniform heating.
Practice has proved that non-oil bearing improper installation causes premature bearing damage is one of the reasons. The ferrule assembly and disassembly with the interference is a very difficult thing, so the design of supports, we must consider how IKO cross roller bearing assembly and disassembly and easy assembly and disassembly of the problem. For heavy machinery assembly and disassembly of large bearings often need to design special equipment. If the high-pressure oil removal would need to be designed accordingly oil, pipes and pumps.
Bearings should be cleaned before installation. With anti-rust oil sealed bearing directly available gasoline or kerosene cleaning; thick oil or grease rust rust charged shall, light mineral oil, such as 10 # transformer oil heating oil or fat will melt cooled, then gasoline or kerosene to clean. Sides with shields or seals bearing grease at the factory joined, so when you do not have to clean install. Coated with anti-rust lubricant oil dual IKO cross roller bearings, the installation also without cleaning. In cleaning the installation process, should prevent foreign matter falling into the bearings, the result of slight abrasive will cause between the rolling element and raceway wear, increased noise and vibration.
Oil-bearing assembly and disassembly, mainly through two ways. First, the interference rings onto the shaft or pressed into the bearing hole; First, by heating up a large diameter bearing it, or cooling the bearing outer diameter narrowing it will be easily mounted on the shaft bearing seat or push hole. When pressurized mode, mechanical force or fluid pressure through a dedicated device will force acts directly on the assembly and disassembly of the seat ring, and never allow loading and unloading of force pass through the rolling. Otherwise it will cause the surface of the raceway and rolling elements indentation, resulting in increased noise and vibration damage. If a heating or cooling means for detachably, the heating temperature should be strictly controlled or cooling temperatures. Because the strength of the bearing surface microstructure by the structure of the metal surface, the temperature is too high will cause the tempering effect; temperature was too low will cause embrittlement of the metal surface. Typically the heating temperature does not exceed 100 ℃, the cooling must not end at the lowest temperature of minus 50 ℃. Also to be considered to be uniform heating.
Practice has proved that non-oil bearing improper installation causes premature bearing damage is one of the reasons. The ferrule assembly and disassembly with the interference is a very difficult thing, so the design of supports, we must consider how IKO cross roller bearing assembly and disassembly and easy assembly and disassembly of the problem. For heavy machinery assembly and disassembly of large bearings often need to design special equipment. If the high-pressure oil removal would need to be designed accordingly oil, pipes and pumps.
Roller bearing raceway sounds unusual
Bearing raceway raceway sound and control the sound is running when the bearing, its rolling body raceway rolling issued a slippery continuous sound is unique will happen all the bearings of the basic sound. Sound that is generally bearing raceway sound with other sounds. Greater rigidity of the bearing seat, roll sound pressure level is lower. If the radial clearance is too small, the rolling sound pressure level and the main frequency will decrease as the radial clearance increases dramatically.
roller bearing fatigue failure is a failure surface forms, mainly for fatigue crack initiation, propagation and fracture processes in alternating load faults arising under long-term effects of the metal.
1 .. Overall eccentric bearing low precision approach: use specified levels of precision bearings.
2 .. spindle is bent or housing bore misalignment methods: Repair spindle or cabinet.
3 belt too tight: Adjust the belt so that proper tightness.
4 poor lubrication Methods: provide grade lubricating material and properly cleaned.
5 low quality assembly methods: improving the quality of assembly.
6 bearing housing laps: Replace worn bearings and related components.
7 large axial force method: cleaning, alignment ring seals the gap between the requirements of 0.2 ~ 0.3mm, correct impeller balance hole diameter and the checksum static equilibrium values.
8 Bearing damage: replace the bearings.
Control raceway sound methods are: selection of low-noise bearings that waviness small bearings, judicious selection of the conditions of use. Raceway sound often affect the entire mechanical noise reduction raceway sound can reduce the overall mechanical noise.
roller bearing fatigue failure is a failure surface forms, mainly for fatigue crack initiation, propagation and fracture processes in alternating load faults arising under long-term effects of the metal.
1 .. Overall eccentric bearing low precision approach: use specified levels of precision bearings.
2 .. spindle is bent or housing bore misalignment methods: Repair spindle or cabinet.
3 belt too tight: Adjust the belt so that proper tightness.
4 poor lubrication Methods: provide grade lubricating material and properly cleaned.
5 low quality assembly methods: improving the quality of assembly.
6 bearing housing laps: Replace worn bearings and related components.
7 large axial force method: cleaning, alignment ring seals the gap between the requirements of 0.2 ~ 0.3mm, correct impeller balance hole diameter and the checksum static equilibrium values.
8 Bearing damage: replace the bearings.
Control raceway sound methods are: selection of low-noise bearings that waviness small bearings, judicious selection of the conditions of use. Raceway sound often affect the entire mechanical noise reduction raceway sound can reduce the overall mechanical noise.
2013年8月22日星期四
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 speed bearings, speed range and thus the greater the 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 speed bearings, speed range and thus the greater the 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.
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