CN100365295C - High precision hot press silicon nitride ceramic ball bearing and its manufacturing method - Google Patents
High precision hot press silicon nitride ceramic ball bearing and its manufacturing method Download PDFInfo
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- CN100365295C CN100365295C CNB2004100888565A CN200410088856A CN100365295C CN 100365295 C CN100365295 C CN 100365295C CN B2004100888565 A CNB2004100888565 A CN B2004100888565A CN 200410088856 A CN200410088856 A CN 200410088856A CN 100365295 C CN100365295 C CN 100365295C
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Abstract
A heat pressing silicon nitride ceramics ball bearing with high precision and a method for manufacture same belong to the bearing production technology, which is suitable for installation at a numerically controlled machine with high precision, high rotary speed and top grade and at a machining center principal shaft. The heat pressing silicon nitride ceramics ball bearing with high precision in accordance with the present invention comprises an inner ring and an outer ring made from steel, with each respectively being equipped with a ball bearing circular arc rollaway nest; a ceramic ball rolling body set between the ball bearing rollaway nests of the inner and outer rings; a rolling body spacing ring, or a retainer, mounted between the inner and outer rings and used for holding the ceramic ball; and is characterized in that said ceramic ball rolling body is obtained through a conical contour grinding process and technical equipment, with the accuracy thereof achieving G5 and G3. The present invention is characterized as follows: the extreme operational speed is high; the running accuracy is high; it is high temperature resistant and is suitable for running dry; the weight is light; it can work stably at a high-corrosivity medium for a long time; the standardize degree is high, it is convenient to maintain and interchange.
Description
Technical field
The present invention relates to a kind of highi degree of accuracy angular contact ball bearing, particularly relate to a kind of high precision hot press silicon nitride ceramic ball bearing and manufacture method thereof, belong to the bearing manufacturing technology, be suitable for being installed on highi degree of accuracy, high rotating speed, high-grade, digitally controlled machine tools and the machining center main shaft.
Background technique
Numerical control machine tool is the important foundation equipment of national economy, and it embodies the comprehensive strength of a country.And the supporting of the core of main shaft of numerical control machine tool is the high speed and precision ball bearing, and the steel ball rolling element in this ball bearing is laterally kept by the retainer of steel institute, and steel ball is arranged in the raceway of the Internal and external cycle that also is formed from steel.The major defect of these known bearings is to be restricted in the life-span under the high rotating speed.This be because the bad performance with surface of rubbing action make steel ball with also be that two circles that are formed from steel contact, under the condition of running up, to cause bearing temperature rise to raise rapidly, consequently cause bearing performance to descend rapidly, in addition, also damage lubricant grease and oil, cause the lost of life of bearing.
For this reason, the high performance ceramic bearing of high speed and precision ball bearing----of a new generation is being developed in countries in the world always, begin since U.S. NASA company succeeded in developing the first cover ceramic bearing in 1972, high precision hot press silicon nitride ceramic ball bearing is focus and the difficult point competitively studied of each industrial powers in the world always.This is to have excellent physical properties such as density is good, hardness is high, thermal expansion coefficient is little, Young's modulus is big, compressive strength is high, corrosion-resistant in view of hot pressed silicon nitride (HPSN), it is reported, Japan NSK corporation plan is all used the high speed hard-disk bearing of computer instead ceramic ball bearing in several years of future, with the rotating speed of raising hard disk and the stability of main frame; The companies such as open country, gloomy essence, Nigata, Kyocers of herding have put on display high-speed machine tool and the machining center that adopts ceramic ball bearing one after another; The FAG of Germany just is devoted to the exploitation of ceramic bearing main axle unit at middle nineteen seventies; The ceramic ball rolling element that U.S. Norton company adopts the HIP method to produce can be rated as first-class level in the world, and SKF also once repeatedly is reported in the achievement in research of ceramic ball bearing aspect.No. 00812640.2, the Chinese invention patent application that SNFA of France submits has also provided a kind of " the mixing ball bearing with ceramic balls and steel ring ", and it comprises: an inner ring that is formed from steel and an outer ring, and inner ring and outer ring have the ball bearing groove respectively; The all balls that are arranged between the ball bearing groove and contact with it; One is arranged between the Internal and external cycle to keep the ball cage of ball; And two lip rings that between Liang Quan, radially extend basically, in order to oiling agent is remained in the volume that contains ball and cage ring, and oiling agent is limited between Liang Quan and two Sealings, it is characterized in that ball is formed by ceramic post sintering.Because this mixing ball bearing is exclusively used in aircraft industry, especially be applied to helicopter tail gear case, be used to drive the helicopter tail rotor, thereby its structure and precision are unsuitable for all being applied on highi degree of accuracy, high rotating speed, high-grade, digitally controlled machine tools and the machining center main shaft.At home, to the research of ceramic bearing also under test.Wherein main cause is not enough to the mass production processes and the High Efficient Machining Technology research of high precision hot press silicon nitride ceramic ball, processing technique to structural design, optimization and the bearing parts of high-precision ceramic ball bearing lacks research, more lacks the research of engineering practical application and industrialization aspect.
Because the hot pressed silicon nitride (HPSN) material belongs to extremely unmanageable hard brittle material, can only conditionally provide the ceramic ball below 10 grades at present on the international market.G5 level and G3 level ceramic ball are bought nowhere, and corresponding high-precision ceramic bearing also can't be bought.Therefore, development numerical control machine tool and crucial common technology thereof have been listed country " 15 " development in science and technology plan in.Developing the high precision hot press silicon nitride ceramic ball bearing with China's independent intellectual property right as early as possible is the task of top priority.
Summary of the invention
The objective of the invention is to overcome the above-mentioned deficiency of prior art, improve by research, a kind of running accuracy height, price performance is reasonable, easy to use, reliability is high high precision hot press silicon nitride ceramic ball bearing and manufacture method thereof have been provided, this ball bearing can be under high rotation speed operation condition, greatly prolong the life-span of bearing, and the characteristics that can keep ball bearing highi degree of accuracy and high stability, thereby reduce the cost of maintaining.
The technological scheme that the present invention provides is: this high precision hot press silicon nitride ceramic ball bearing comprises:
An inner ring and an outer ring of being formed from steel, inner ring and outer ring have the ball bearing arc raceway respectively;
The ceramic ball rolling element that is arranged between the Internal and external cycle ball-bearing groove and contacts with it, the ceramic ball rolling element is obtained by taper grinding process technique and technical equipment, and its precision reaches the G5 level at least;
One is arranged between the Internal and external cycle to keep the rolling element cage ring of ceramic ball, i.e. retainer.
Because described rolling element is formed by ceramic post sintering and its precision reaches the G5 level at least, promptly ball diameter variation VDWS is no more than 0.13, and deviation from spherical form Δ δ is no more than 0.13, and surface roughness Ra is no more than 0.020.Therefore, characteristics of the present invention are mixing ball bearings of a kind of angle contacting type, its the performance on surface with rubbing action by contact with each other, be used to the stupalith pairing of making the steel of circle and making rolling element, make rolling element with enclose between contact and be improved.Compare with traditional bearing, owing to reduced the heating of contact segment, thereby the performance that is decided by the contact of bearing wear and heating is improved and cause the decay of lubricant grease to reduce, therefore, can reduce the lubricated cost of bearing, simultaneously, because the temperature rise of bearing descends, thereby improved antiwhip, prolonged the life-span of bearing, make the life-span of bearing bring up to about about 3 times, thereby improved bearing highi degree of accuracy and high stability energy greatly, and greatly reduce the cost of maintenance.
Purpose to better implement the present invention, the described rolling element that forms by ceramic post sintering to small part by Si
3N
4Constitute, but surplus ZrO
2Or Al
2O
3, certainly, also can all adopt Si
3N
4Or ZrO
2Or Al
2O
3This is that the stupalith of having developed at present has silicon nitride (Si because stupalith has multiplely
3N
4), silicon carbide (SiC), titanium carbide (TiC), zirconium oxide (ZrO
2), aluminium oxide (Al
2O
3) and fiber reinforcement glass and Reinforced Glass-Ceramic Composites etc., its microstructure and performance have nothing in common with each other, and therefore, not all stupalith all is fit to be used for making bearing.Stupalith is centrifugal force and the inertial force for the rolling element that reduces high speed rotating as the main purpose of rolling bearing material, with the speed up that adapts to bearing and the requirement of high temperatureization.Therefore, that at first considers is had high strength and high hardness characteristic as the low density of bearing material with by satisfying to use under the worst hot case condition, in addition, also must have dimensional stability under different temperatures as bearing material, to guarantee that bearing is under the temperature variation working condition, keep accurate size and accurate the cooperation, under particular surroundings, also must possess anticorrosive, anti-resolving power.From present research situation, silicon nitride is the most suitable present stupalith that is used for making rolling bearing.Compare with Bearing Steel with several stupaliths, its advantage mainly shows: low density, medium Young's modulus, high hot-pressing strength, low thermal coefficient of expansion and good inherent chemical characteristics thereof.
Purpose to better implement the present invention, the steel of described bearing inner race and outer ring can be selected from following steel: traditional bearing steel, preferably M50 or 100C6; Stainless steel, preferably 440C or XD15N; Structure nitriding or case hardening steel, preferably 32CDV13 or M50NIL.
Purpose to better implement the present invention, described retainer are preferably polyethers ethyl ketone PEEK by the polymer material molding and forming.Existing retainer is made of two half cage rings with respect to a radial plane symmetry, be resisted against on another half cage ring along these plane one and half cage rings, each cage ring all is the corolla form, these half cage rings are held the axial rivet between some complementary recess guard shield, half cage ring of rolling element and are axially relatively combined each other by formation, like this, cage ring centers at inner ring, thereby can maintain cage ring.Its major defect is, structure is complicated, and it is unfavorable to use under hot environment.And the polymer retainer is compared with the metal retainer not only because low price, and excellent performance, and its main feature is: density is low, and good springiness is corrosion-resistant, resist chemical, and shock resistance is good, and sliding is good.Owing to the molding and forming of polymer retainer energy, its geometry design extremely helps the work of bearing simultaneously.Polyethers ethyl ketone PEEK (Polyetheretherkerone) is the best retainer material that is used for ceramic bearing.PEEK and to hinder the friction factor minimum between HIPSN be 0.028, and almost be not worn.And, in the bulk ceramics bearing test, prove that it can satisfy the high speed requirement.Adopt the high-speed spindle bearing of oil lubrication, adopt the polymer retainer of thin type usually.This retainer light weight, centrifugal force is little in the operation process, and bear vibration is little, and the intensity height.Keep big space between thin type retainer and inner ring rib, help the lubricated of bearing.The retainer that the grease lubrication profile shaft holds should be suitably thicker.For increasing bearing self oil storage capacity, should on retainer, leave corresponding oil duct.
Purpose to better implement the present invention, described retainer adopts the retainer of outer ring guide structure.This is that the retainer running speed is far below the bearing inner race running speed because high-speed spindle bearing is when running well.By fixed outer ring lip-guided retainer, can significantly reduce grazing and vibration between retainer and guide surface, make the work of bearing more stable.High-speed spindle bearing inner ring radiating condition is poor, should obtain more sufficient cooling with lubricated.Adopt outer ring guiding retainer, it is lubricated fully to help making bearing to obtain.Lubricant oil sprays into from the space between inner ring and the retainer, and bear inner ring grooved railway is cooled off fully with lubricated.With the rotation of ball, the lubricant oil of sending into the bearing inner race raceway groove constantly is thrown into outer ring raceway under the drive of spheroid and under self action of centrifugal force, and it is good lubricated that guide surface and raceway groove are all obtained.So under equal lubricating condition, the bearing life of outer ring guiding retainer will be longer than the plain bearing of inner ring guiding retainer.
The invention provides a kind of manufacture method of high precision hot press silicon nitride ceramic ball bearing, it is characterized in that:
A. manufacturing procedure is
1. slightly grind
At first the ceramic ball base is pressed the maximum diameter grouping, at grinding pressure (N/ ball) 8～15, grinding rate (r/min) 800～2500, wear particle size 170
#～200
#Grind under the condition, to eliminate the bigger preparation defective in ball base surface, reduce deviation from spherical form, unified sphere diameter and the efficient surplus of removing are to satisfy the sphere diameter requirement, its accuracy test result is: batch variation in diameter amount (μ m) 2～2.5, variation in diameter amount (μ m) 2～2.5, deviation from spherical form (μ m) 2, waviness (μ m) 0.15～0.3, roughness (μ m) 0.8;
2. half lappingout
With the ceramic ball after slightly grinding, at grinding pressure (N/ ball) 6～10, grinding rate (r/min) 450～800 grinds under wear particle size W40, the W10 condition, to revise deviation from spherical form, improve whole work efficiency and quality of processing, its accuracy test result is: batch variation in diameter amount (μ m) 0.8, variation in diameter amount (μ m) 0.7～1.0, deviation from spherical form (μ m) 0.8, waviness (μ m) 0.05～0.07, roughness (μ m) 0.2;
3. lappingout
With the ceramic ball behind half lappingout, at grinding pressure (N/ ball) 3～6, grinding rate (r/min) 160～270, grind under the wear particle size W5 condition, to improve the precision and the surface quality of ball, its accuracy test result is: batch variation in diameter amount (μ m) 0.4, variation in diameter amount (μ m) 0.4～0.5, deviation from spherical form (μ m) 0.4, waviness (μ m) 0.02～0.03, roughness (μ m) 0.05;
4. super lappingout
With the ceramic ball behind the lappingout, at grinding pressure (N/ ball) 1～2, grinding rate (r/min)＜160 grinds under wear particle size W1, the W0.5 condition, to improve the precision and the surface quality of ball, and guarantee enough machining allowance so that precision progressively improves, its accuracy test result is: batch variation in diameter amount (μ m) 0.13, variation in diameter amount (μ m) 0.1, deviation from spherical form (μ m) 0.1, waviness (μ m) 0.009, roughness (μ m) 0.02～0.03;
5. polishing
With the ceramic ball behind the super lappingout, at grinding pressure (N/ ball) 0.5～1, grinding rate (r/min)＜160, wear particle size Fe
2O
3Grind under the condition, to improve surface roughness, its accuracy test result is: batch variation in diameter amount (μ m) 0.13, variation in diameter amount (μ m) 0.1, deviation from spherical form (μ m) 0.1, waviness (μ m) 0.009, roughness (μ m) 0.01～0.02, inspect and be the ceramic ball finished product rolling element after qualified, its precision level reaches the G5 class precision of steel ball at least;
B. the lapping device of abrasive machining ceramic ball, include top lap and following abrasive disk, wherein top lap (11) is recessed plate-like, top lap is installed in an end of transmission shaft, adopt flexible member to be connected between the other end of transmission shaft and the machine tool chief axis, the middle part of transmission shaft also is provided with angular contact ball (10) bearing, the two ends end cap of this angular contact ball bearing bearing cap is provided with nut and passes sleeve, the other end of this sleeve pierces into and is positioned at, axle sleeve on the guide pillar of following abrasive disk both sides, be provided with round nut on the axle sleeve, pad and spring, following abrasive disk (13) is installed on the base of lathe, and guide pillar also is fixed on the base of lathe.
In above-mentioned technology, these two parameters of grinding pressure and lap speed are closely related, and influence grinding precision and grinding efficiency simultaneously, therefore, when determining its occurrence, must consider simultaneously, take into account mutually.
To take into account the grinding precision and the grinding efficiency of ceramic ball when (1) selecting grinding pressure P: as lay particular emphasis on grinding precision (during lappingout), P should be smaller; As laying particular emphasis on grinding efficiency (when slightly grinding), P can be greatly;
Also to take into account the grinding precision and the grinding efficiency of ceramic ball when (2) selecting lap speed ω: as lay particular emphasis on grinding precision (during lappingout), ω should be smaller; As laying particular emphasis on grinding efficiency (when slightly grinding), ω can be greatly;
(3) the last of P and ω determined, also must be by the field experiment of a large amount of ceramic ball grindings, to obtain best grinding effect.
Because pottery belongs to brittle material, under the effect of abrasive particle, the surface can produce different crackles, so the abrasive machining of ceramic ball rolling element will be carried out step by step, by slightly finishing to the smart multiple working procedure that divides.Operation for a long time auxiliary time long, process time is short, it is long that the cleaning of ball picks and places the time, great advantage is can reasonable distribution machining allowance, per pass process efficiency height.Operation after a little while auxiliary time short, long processing time, the abrasive grain difference is big, must guarantee that enough machining allowance could remove defective that previous process is stayed and reach and improve machining accuracy gradually.The division of operation will comprehensively determine that when big in batches, process division helps the raising of whole efficiency according to manufacturing batch, ball base surplus, error size etc.
When slightly grinding: should at first the ball base be pressed the maximum diameter grouping, shorten the erratic process of grinding initial stage, and reduce it as far as possible and beat to improve grinding efficiency, the ceramic ball base has corner angle, therefore, initial in processing, should low speed, the too high institute of rotating speed causes vibration big, rotating speed also may appear when high, frictional force is big, causes top lap to be stuck owing to ball is not round and changes motionless phenomenon, and this all influences processing.Therefore, rotating speed can not be too high, and pressure can suitably strengthen, and is machined to this understanding corner angle are removed, and the ball base is till certain sphere.Can consider to improve work efficiency then, from actual processing effect, under high-speed case, the eliminating rate of several pressure is all higher, and therefore, rotating speed can increase substantially.But rotating speed is too high, when pressure is big, vibrates very greatly, therefore, can consider suitably to reduce pressure under the prerequisite of work efficiency guaranteeing, reduces vibration.
When half lappingout: because this procedure of half lappingout is in order to carry out the transition to lappingout, mainly to consider work efficiency, to hold concurrently to consider deviation from spherical form.Therefore, should not use excessive speeds, excessive pressure, in order to revise deviation from spherical form (because the correction of deviation from spherical form under low speed, the low-pressure than at a high speed, good under the high pressure), improve whole work efficiency and quality of processing.
When lappingout: the purpose of this procedure is to improve the precision and the surface quality of ball.The removal amount size should guarantee to eliminate defective that previous process is stayed.Therefore, rotating speed and pressure are all wanted suitably, once add abrasive material after process time also should consider to some extent.
When super lappingout: this procedure does not just improve the precision and the surface quality of ball, also should guarantee enough machining allowance so that precision progressively improves, and surplus is too little, can't reach highi degree of accuracy.Therefore, rotating speed and pressure when rotating speed and pressure ratio lappingout will hang down, once add abrasive material after, process time is longer, can progressively improve machining accuracy and surface quality.
When polishing: the purpose of polishing is to improve surface roughness.From actual effect, use the buffing material chromium oxide lower+lappingout oil polishing effect better than ceramic hardness, under low speed, low pressure conditions, sphere diameter changes little after processing a few hours, surface roughness Ra can reach 0.01 μ m or littler.
According to fixed each procedure processing HIPSN ceramic ball, 60 ~ 100 in the every batch of processable ceramic ball, about 30h, ceramic ball finished product can reach G5, G3 level level when shared.
For guaranteeing grinding efficiency and precision, should rationally arrange operation according to the surplus of batch size, ball base, by slightly progressively reducing grinding pressure and rotating speed to essence.The precision of lapping device has a significant impact the raising of grinding efficiency and precision, mainly should guarantee parallelism, perpendicularity, off-centre and the guiding accuracy of upper and lower abrasive disk, and this is directly connected to the stressed and motion state of ball.
Grinding abrasive can use diamond abrasive, also can use SiC, B4C abrasive material, and the diamond abrasive cost is higher, the work efficiency height.Allocate rational lapping paste and help to improve grinding precision and efficient.Need take measures abrasive material is suspended in lapping liquid, the interpolation of lapping paste will be followed a small amount of principle repeatedly.When slightly grinding, removal amount is big, and abrasive dust is many, stops up the abrasive disk raceway groove easily, influences the spin motion of ceramic ball, makes machining accuracy and work efficiency all can not get guaranteeing.Therefore, must in time remove raffinate, fill lapping paste.Experiment showed, and can raise the efficiency in view of the above about 20%, reduce 8 hours process times/about criticizing.
When slightly grinding, the abrasive disk material will be selected mild steel for use, as 45# steel, cast iron, helps the ball track to form, unified fast sphere diameter.During lappingout, the abrasive disk material should be selected hard steel for use, for keeping kinematic accuracy for a long time, as Chilled Hardened Steel.Abrasive disk is roughly 80h, 120h in life time thick, lappingout.
Also include the lapping device of abrasive machining ceramic ball in the technological scheme that the present invention provides, it includes top lap and following abrasive disk, it is characterized in that top lap (11) is recessed plate-like, top lap is installed in an end of transmission shaft, adopt flexible member to be connected between the other end of transmission shaft and the machine tool chief axis, and the drive top lap rotates with angular velocity with the lathe main shaft, the middle part of transmission shaft also is provided with angular contact ball (10) bearing, the two ends end cap of this angular contact ball bearing is provided with nut and passes sleeve, the other end of this sleeve pierces into and is positioned at, axle sleeve on the guide pillar of following abrasive disk both sides, be provided with round nut on the axle sleeve, pad and spring, can change grinding pressure, following abrasive disk (13) is installed on the base of lathe and maintains static, guide pillar also is fixed on the base of lathe, and ceramic ball to be ground places among the groove between top lap and the following abrasive disk.
Described machine tool chief axis can be the drill press spindle or the vertical milling head of milling machine, require machine tool chief axis that level or stepless speed regulation can be arranged between 100～5000 rev/mins, and can make top lap that ceramic ball is applied downward grinding pressure, this grinding pressure can require to regulate with different grindings.
Compared with prior art, beneficial effect of the present invention is:
1). limit running speed height;
2). the running accuracy height;
3). high temperature resistant, but and running dry;
4). in light weight;
5) but. long-term stable operation in some highly corrosive media;
6). the standardization level height, be convenient to maintenance, exchange;
7). little to the machine tool structure change, be convenient to maintaining.
8). be applied on the machine tool chief axis unit, the life-span in operation process has improved more than 3 times than traditional steel ball bearing, and can need not add lubricant grease at operation process.
9). the process division science of taper grinding process technique, by slightly progressively reducing grinding pressure and rotating speed to essence, the surplus reasonable distribution, per pass process efficiency height, its work efficiency is higher than traditional V-shaped groove polishing.
10). for high-speed, high precision machine-tool spindle system and automatic line provide crucial fundamental parts, accelerated numerical control machine tool towards at a high speed, the paces of efficient, highi degree of accuracy development, promote the Plant reconstruction plant modernization of big-and-middle-sized machining enterprise such as Bearing Factory, engine works, Gear Factory, and China is reached the international leading level in the research in this field.
Description of drawings
Fig. 1 is the radial section figure that the ratio of ball bearing is amplified;
Fig. 2 is the drawing in side sectional elevation that the ratio of two circles of Fig. 1 bearing is amplified;
Fig. 3 is the radial section figure of the moderate proportions of Fig. 1 retainer;
Fig. 4 is the left view of Fig. 3;
Fig. 5 is in the ceramic ball grinding process, the kinematics analysis figure of ceramic ball;
Fig. 6 is an electric main shaft of digital control machine tool modular construction sketch of using hot press silicon nitride ceramic ball bearing;
Fig. 7 is a ceramic ball grinding mechanism structural representation;
Number in the figure: 1. outer ring, 2. inner ring, 3. ceramic ball rolling element, 4. retainer, 5. outer raceway, 6. interior raceway, 7. circular port, 8. seal ring, 9. adjustment pad, 10. angular contact ball bearing, 11. top lap, 12. round nuts, 13. times abrasive disks, 15. main shafts, 16. round nut, 17. pads, 18. axle sleeves, 19. springs, 20. axle sleeve, 21. bolts, 22. bearing caps, 23. high precision hot press silicon nitride ceramic ball bearings, 24. main shaft, 25. cooling water inlets, 26. coolant outlets, 27. mist of oils inlet.
Embodiment
Below in conjunction with embodiment concrete technological scheme of the present invention is described further:
Comprise as Fig. 1～high-accuracy hot press silicon nitride ceramic ball bearing shown in Figure 4: an inner ring 2 that is formed from steel and an outer ring 1, inner ring 2 and outer ring 1 have the arc raceway 5,6 of one of two circular arc raceways that face each other respectively; Be arranged on the some ceramic ball rolling elements 3 that also contact with it between the raceway 5,6 of Internal and external cycle; One is arranged between the Internal and external cycle 1,2 to keep the rolling element cage ring of ceramic ball rolling element 3, and promptly retainer 4.This ball bearing is the angle contacting type, that is to say, outer ring 1 and inner ring 2 have an outer raceway 5 and an interior raceway 6 separately respectively, they face each other, and concave surface separately is towards the other side, in this example, outer ring 1 has fore shaft, makes bearing inseparable after assembling.The assembling of this ball bearing adopts the outer ring to add thermal expansion, to assemble.Ceramic ball rolling element 3 is arranged between raceway 5 and 6, and radially with the bearing that is designed to bearing radial force basically and certain axial load in these raceways 5 and 6 roll and contact.Ceramic ball rolling element 3 is formed by the Si3N4 ceramic post sintering, and its precision level reaches the G5 class precision of steel ball at least, and part reaches the G3 class precision of steel ball.Two circles 1 and 2 are made by the traditional bearing steel of for example M50 or 100C6 type.
Retainer 4 adopts the polymer retainer of thin type, polymer material is polyethers ethyl ketone PEEK, these retainer 4 molding and forming, and the friction factor minimum between retainer 4 and the ceramic ball rolling element 3 is 0.028, and almost be not worn, can satisfy the running requirements of high speed, high temperature.By fixed outer ring lip-guided retainer, can significantly reduce grazing and vibration between retainer and guide surface, make the work of bearing more stable.In addition, this structure also is convenient to the lubricated of bearing and is cleaned.
The manufacture method of the ceramic ball among this embodiment is the taper polishing, and its grinding condition such as following table are listed:
During grinding, the ceramic ball grinding mechanism that includes top lap and following abrasive disk that should use the present invention to provide, as shown in Figure 7, this ceramic ball grinding mechanism includes top lap 11 and following abrasive disk 13, wherein top lap 11 is installed in an end of transmission shaft, adopt flexible member to be connected between the other end of transmission shaft and the machine tool chief axis 15, and drive top lap 11 rotates with angular velocity with lathe main shaft 15, the middle part of transmission shaft also is provided with angular contact ball bearing 10, the bearing cap 22 two ends end caps of this angular contact ball bearing 10 are provided with nut 21 and pass sleeve, the other end of this sleeve pierces into and is positioned at, axle sleeve 20 on the guide pillar of following abrasive disk both sides, be provided with round nut 12 and 16 on the axle sleeve 20, pad 17 and spring 19, can change grinding pressure, following abrasive disk 1 is installed on the base of lathe and maintains static, guide pillar also is fixed on the base of lathe, this machine tool chief axis is a drill press spindle, this main shaft can have level or stepless speed regulation between 100～5000 rev/mins, and can make top lap that ceramic ball is applied downward grinding pressure, this grinding pressure can require with the grinding of different operations to regulate.Certainly, under the prerequisite that satisfies the grinding requirement, also can adopt
The grinding condition table
| Sample | HIPSN: ￠ 8 ± 0.15; The ball base |
| Abrasive material | Diamond abrasive: 170 #/200 #～W0.5; Polishing: Fe 2O 3Diamond wheel: 11A 2(BW 1)150×40×32×5D170 #(280 #)M100 |
| Auxiliary agent | Lubricant oil, fat, water, kerosene and composition thereof |
| Abrasive concentration | 5％～30％ |
| Single batch of nodule number (individual) | 30，40，50 |
| Every ball (mm) | ￠ 11, ￠ 8, ￠ 6 steel balls |
| Grinding pressure (N/ ball) | 0.5～20 |
| The abrasive disk material | Cast iron, mild steel, Chilled Hardened Steel, rubber |
| Lap speed | 160～4000r/min |
| Abrasive disk parameter (mm) | R A＝132.5，R B＝140，R C＝129，Φ＝30° |
| Spin angle θ | θ＝46.5° |
| Spin velocity (r/min) | 5.6～244 |
| Revolution angular velocity (r/min) | 0.51～12.8 |
Existing other grinding equipment carries out abrasive machining to the ceramic ball base of buying from the market.The precision of lapping device has a significant impact the raising of grinding efficiency and precision, mainly should guarantee parallelism, perpendicularity, off-centre and the guiding accuracy of upper and lower abrasive disk, and this is directly connected to the stressed and motion state of ball.
The taper polishing that adopts includes following operation:
1). slightly grind
The ceramic ball base that at first will buy from the market divides into groups by maximum diameter, at grinding pressure (N/ ball) 8～15, grinding rate (r/min) 800～2500, grind under wear particle size 170#～200# condition, to eliminate the bigger preparation defective in ball base surface, reduce deviation from spherical form, unified sphere diameter and the efficient surplus of removing are to satisfy the sphere diameter requirement;
2). half lappingout
With the ceramic ball after slightly grinding, at grinding pressure (N/ ball) 6～10, grinding rate (r/min) 450～800 grinds under wear particle size W40, the W10 condition, to revise deviation from spherical form, improves whole work efficiency and quality of processing;
3). lappingout
With the ceramic ball behind half lappingout, at grinding pressure (N/ ball) 3～6, grinding rate (r/min) 160～270 grinds under the wear particle size W5 condition, to improve the precision and the surface quality of ball;
4). super lappingout
With the ceramic ball behind the lappingout, at grinding pressure (N/ ball) 1～2, grinding rate (r/min)＜160 grinds under wear particle size W1, the W0.5 condition, with the precision and the surface quality of raising ball, and guarantees enough machining allowance so that precision progressively improves;
5). polishing
With the ceramic ball behind the super lappingout, at grinding pressure (N/ ball) 0.5～1, grinding rate (r/min)＜160, wear particle size Fe
2O
3Grind under the condition, improving surface roughness, be ceramic ball finished product after qualified through inspecting.
What list below is the testing result of each operation accuracy test result and ceramic ball finished product, and wherein the testing result of ceramic ball finished product provides after being tested by national bearing quality supervision and inspection center.
From testing result: the precision level of the ceramic ball that processes has reached the G5 class precision of steel ball, and the part ball reaches the G3 class precision.According to above-mentioned each procedure processing ceramic ball, 60～100 of the every batch of machinable ceramic ball finished product are when shared about 30h.
Up till now, also do not have the figure tolerance of special ceramic ball and the regulation of surface roughness, therefore, the grade of accuracy of ceramic ball is still with reference to the regulation of steel ball grade of accuracy.
The grade of tolerance of the above-mentioned steel ball of mentioning stipulates that by GB/T308-1989 steel ball is divided into 3,5,10,16,20,28,40,60,100,2,000 ranks by size, the figure tolerance made, and precision successively from high to low.The figure tolerance of each grade steel ball and surface roughness according to the form below regulation.
The steel ball grade of tolerance adds digital watch with symbol G and shows.
Ball diameter variation: the minimum and maximum single diameter of the actual measurement of a ball poor;
Deviation from spherical form: in arbitrary radial plane, the maximum radial distance on the external spheroid of ball contoured surface and the ball contoured surface between any point.
Ceramic ball finished product testing result (μ m)
| Content | Rough surface | Deviation from spherical form | Ball diameter variation | With the dish degree | Waviness |
| 9.5 ZrO 2 | 0.01～ | 0.11 | 0.13 | 0.12 | 0.010 |
| 9.5 Al 2O 3 | 0.01～ | 0.12 | 0.13 | 0.13 | 0.010 |
| 7.5HIPSN | 0.01 | 0.08 | 0.07 | 0.10 | 0.009 |
Each operation accuracy test
The grade of tolerance of steel ball
| The grade of tolerance | Ball diameter variation V DWS | Deviation from spherical form | Surface roughness Ra |
| Be no more than | |||
| 3 | 0.08 | 0.08 | 0.012 |
| 5 | 0.13 | 0.13 | 0.020 |
| 10 | 0.25 | 0.25 | 0.25 |
| 16 | 0.4 | 0.4 | 0.032 |
| 20 | 0.5 | 0.5 | 0.04 |
| 28 | 0.7 | 0.7 | 0.05 |
| 40 | 1.0 | 1.0 | 0.08 |
| 60 | 1.5 | 1.5 | 0.10 |
| 100 | 2.5 | 2.5 | 0.125 |
| 200 | 5 | 5 | 0.2 |
As shown in Figure 5, the grinding kinematics analysis of single ceramic ball in grinding process: the point of contact of establishing upper and lower abrasive disk and ceramic ball is respectively A, B, C.Ceramic ball only is subjected to the effect of abrasive disk, and following abrasive disk is fixed, and top lap fricton-tightly drives ceramic ball by the point of contact with ceramic ball and does the grinding motion.The angular velocity of top lap is ω, and the revolution radius of three point of contact is respectively R
A, R
B, R
C, the ceramic ball radius is r.The nothing of ceramic ball is skidded, and grinding moves is made up of revolution and rotation, revolution angular velocity Ω (around hollow shaft), spin velocity ω
b(around the ceramic ball axis of rotation).The nothing of ceramic ball skidded grind motion, the axis of rotation perseverance of ceramic ball remains on the big disk of ceramic ball longitude section, spin velocity ω
bThe direction of vector on this plane represented by θ.Wherein, the abrasive disk parameter is: R
A=132.5, R
B=140, R
C=129, φ=30.
As shown in Figure 6, the hot press silicon nitride ceramic ball bearing that the present invention provides is installed in the situation on the electric main shaft of digital control machine tool unit.Wherein, 23 is high precision hot press silicon nitride ceramic ball bearing, and 24 is main shaft, and 25 is the cooling water inlet, and 26 is coolant outlet, and 27 are the mist of oil inlet.The electricity main axle unit is as high-speed numeric control lathe most key part, its performance quality has determined the machining accuracy and the manufacturing efficiency of whole high-speed machine tool to a great extent, and the core support unit of high-speed electric main shaft is a high-speed precision bearing, test shows, the centrifugal force of bearing roller will improve and fast rise with rotating speed, make the sliding friction aggravation of rolling element and raceway contact surface, cause bearing life sharply to descend.And the life-span of silicon nitride ceramics mixing ball bearing improves more than three times than the life-span of steel ball bearing.The density of silicon nitride ceramic material approximately is 40% of steel bearing, and low-density silicon nitride is when the underloading high speed operation, and the centrifugal force of rolling element reduces greatly, and the spin motion that is caused by centrifugal force also greatly reduces.Like this, the limit speed of hybrid ceramic ball bearing is improved.Calculating shows that under the high speed light loading condition, the limit speed of the comparable steel ball bearing of limit speed of hybrid ceramic ball bearing improves about 60%.In the application example that provides, vibration values 0.5mm/s when the endoporus circular runout 1um of ceramic bearing Large-power High-Speed electricity main axle unit, end face run-out 1.5um, 30000rpm operation, improved the machining accuracy and the efficient of precision bearing lasso, satisfied at a high speed, the needs of ultra-speed precise working machine tool.
Claims (2)
1. the manufacture method of high precision hot press silicon nitride ceramic ball bearing is characterized in that:
A. manufacturing procedure is
(1). slightly grind
At first the ceramic ball base is pressed the maximum diameter grouping, at grinding pressure (N/ ball) 8～15, grinding rate (r/min) 800～2500, wear particle size 170
#～200
#Grind under the condition, to eliminate the bigger preparation defective in ball base surface, reduce deviation from spherical form, unified sphere diameter and the efficient surplus of removing are to satisfy the sphere diameter requirement, its accuracy test result is: batch variation in diameter amount (μ m) 2～2.5, variation in diameter amount (μ m) 2～2.5, deviation from spherical form (μ m) 2, waviness (μ m) 0.15～0.3, roughness (μ m) 0.8;
(2). half lappingout
With the ceramic ball after slightly grinding, at grinding pressure (N/ ball) 6～10, grinding rate (r/min) 450～800 grinds under wear particle size W40, the W10 condition, to revise deviation from spherical form, improve whole work efficiency and quality of processing, its accuracy test result is: batch variation in diameter amount (μ m) 0.8, variation in diameter amount (μ m) 0.7～1.0, deviation from spherical form (μ m) 0.8, waviness (μ m) 0.05～0.07, roughness (μ m) 0.2;
(3). lappingout
With the ceramic ball behind half lappingout, at grinding pressure (N/ ball) 3～6, grinding rate (r/min) 160～270, grind under the wear particle size W5 condition, to improve the precision and the surface quality of ball, its accuracy test result is: batch variation in diameter amount (μ m) 0.4, variation in diameter amount (μ m) 0.4～0.5, deviation from spherical form (μ m) 0.4, waviness (μ m) 0.02～0.03, roughness (μ m) 0.05;
(4). super lappingout
With the ceramic ball behind the lappingout, at grinding pressure (N/ ball) 1～2, grinding rate (r/min)＜160 grinds under wear particle size W1, the W0.5 condition, to improve the precision and the surface quality of ball, and guarantee enough machining allowance so that precision progressively improves, its accuracy test result is: batch variation in diameter amount (μ m) 0.13, variation in diameter amount (μ m) 0.1, deviation from spherical form (μ m) 0.1, waviness (μ m) 0.009, roughness (μ m) 0.02～0.03;
(5). polishing
With the ceramic ball behind the super lappingout, at grinding pressure (N/ ball) 0.5～1, grinding rate (r/min)＜160, wear particle size Fe
2O
3Grind under the condition, to improve surface roughness, its accuracy test result is: batch variation in diameter amount (μ m) 0.13, variation in diameter amount (μ m) 0.1, deviation from spherical form (μ m) 0.1, waviness (μ m) 0.009, roughness (μ m) 0.01～0.02, inspect and be the ceramic ball finished product rolling element after qualified, its precision level reaches the G5 class precision of steel ball at least;
B. the lapping device of abrasive machining ceramic ball, include top lap and following abrasive disk, wherein top lap (11) is recessed plate-like, top lap is installed in an end of transmission shaft, adopt flexible member to be connected between the other end of transmission shaft and the machine tool chief axis, the middle part of transmission shaft also is provided with angular contact ball (10) bearing, the two ends end cap of this angular contact ball bearing bearing cap is provided with nut and passes sleeve, the other end of this sleeve pierces into and is positioned at, axle sleeve on the guide pillar of following abrasive disk both sides, be provided with round nut on the axle sleeve, pad and spring, following abrasive disk (13) is installed on the base of lathe, and guide pillar also is fixed on the base of lathe.
2. the lapping device of abrasive machining ceramic ball, include top lap and following abrasive disk, it is characterized in that top lap (11) is recessed plate-like, top lap is installed in an end of transmission shaft, adopt flexible member to be connected between the other end of transmission shaft and the machine tool chief axis, the middle part of transmission shaft also is provided with angular contact ball (10) bearing, the two ends end cap of this angular contact ball bearing bearing cap is provided with nut and passes sleeve, the other end of this sleeve pierces into and is positioned at, axle sleeve on the guide pillar of following abrasive disk both sides, be provided with round nut on the axle sleeve, pad and spring, following abrasive disk (13) is installed on the base of lathe, and guide pillar also is fixed on the base of lathe.
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