Bearing of pottery and porcelain studies in the application in unit of main shaft of numerical control machine tool

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Summary: Bearing of pottery and porcelain with its good performance, the application in unit of high speed main shaft is wide with each passing day. Carry theoretical analysis and experimental research, characteristic to uniter than analysing two sort main shaft temperature rise, vibration, the actual application that is bearing of pottery and porcelain provides certain basis. To raise productivity and treatment precision, the tide that machine tool main shaft turns development to high speed is conspicuous. Bearing of pottery and porcelain is had be able to bear or endure light, life grows high speed, weight wait for good performance, in the machinery that works below the condition such as high speed and special environment, getting applied stage by stage. Unit of high speed main shaft is one of decisive technologies that develop machine tool of medium, high-grade numerical control. In recent years, the numerical control machine tool that abroad manufactures or machining center, system of its main shaft is very much used bearing of pottery and porcelain and structure of electric machinery main shaft, namely alleged report main shaft. Electric main shaft is a kind of of unit of main shaft of machine tool high speed idealer structure, home still is in in the research of this respect start level. The core of unit of high speed main shaft is bearing of high speed nicety, its function stand or fall will affect the character of service of main shaft unit directly. As speed rise, the temperature of bearing is elevatory, vibration and throat sound increase, life is reduced. Accordingly, the premise that increases main shaft rotate speed is to develop development to give performance bearing of advantageous high speed main shaft. Current, in unit of high speed main shaft, the bearing of main shaft basically uses activity of the bearing that take surplus, liquid to press ball bearing of bearing, pottery and porcelain 3 kinds of forms. The high speed function of magnetism float bearing good, precision is tall, easy implementation is diagnosed and online monitoring. But practice makes clear, this kind of bearing is measured as a result of electromagnetism control a system too complex, fail to get applied extensively up to now. Liquid activity presses bearing integrated the liquid is static the good point that approachs bearing and bearing of liquid dynamic pressure, but this kind of bearing must undertake technically designing according to particular machine tool, independent production, standardization rate is low, care and maintenance is difficult also. Current, apply bearing of most high speed main shaft or ball bearing of mixture pottery and porcelain, roll body uses hot pressing or heat to wait namely static press nitrogen to turn ball of silicon pottery and porcelain, bearing ferrule still is steel group. Rate of standardization of this kind of bearing is high, the price is low, alter to machine tool structure small, facilitating care and maintenance, suit high speed to run a circumstance particularly. Its K value already exceeded 2.

7 × 106. To add the service life of bearing, can increase the wearability of raceway, undertake coating processing or other finishing to raceway. When the theoretical analysis bearing of ball bearing of 1 pottery and porcelain is working, bearing contacts generation stress between scroll body and ferrule, be in contact apparently form osculatory stress ellipse. According to Herts osculatory theory, bearing rolls the contacts ellipse length between body and ferrule, short radius is: A=ma[3Q(1-µc2+1-µs2)]1/32SrEcEs(1)b=mb[3Q(1-µc2+1-µs2)]1/32SrEcEs(2) generation enters the performance data of material of pottery and porcelain, can get: Qoc=1.

112qom(3)dc=0.

In 896dm(4) type: Ma, Mb -- the coefficient D that concerns with elliptical eccentricity -- the stretch approach of ball and ferrule measures Q -- action is rolling the Qo of extra total negative charge on body -- the osculatory stress E of ball and ferrule -- the stretch model of material measures µ -- the Poisson of material is compared C, , the relevant parameter Sr that points to bearing of pottery and porcelain and steel ball bearing respectively -- advocate curvature and by type 3, 4 can see, when low speed.

1 of ball of the pottery and porcelain in ball bearing of pottery and porcelain and steel ferrule.

112 times, be out of shape 89 of the bearing that it is steel.

6% . Below high speed condition, bearing is come from the action of outside force not only, still be rolled by bearing interior body leaves the action of mental efforts. From the action of mental efforts, will make contact stress of area, contact and flexibility to be out of shape increase. As a result of scroll body (ball) density is different, the osculatory stress in ball bearing of pottery and porcelain and steel ball bearing also can differ. In ball bearing of pottery and porcelain, replace steel ball with ball of pottery and porcelain, the density of material of pottery and porcelain and hot coefficient of expansion are smaller than bearing steel, stretch model amount is large. Below condition of high speed movement, the load that comes from bearing interior (moment of force of centrifugal force, top) scale bearing is small, accordingly, the limited speed of ball bearing of pottery and porcelain can get rising, if the limited speed of Si3N4 ball bearing compares steel bearing,rose 60% the left and right sides. The destruction of scroll bearing the form basically has exhaustion to destroy, wear away, the form such as plasticity impress, burn and lubricant invalidation. Below regular job requirement, the destruction of steel bearing is exhaustion is destroyed. Wait with heat static of the ball bearing of pottery and porcelain that presses nitrogen to change ball of silicon pottery and porcelain to replace steel ball set to become destroy a form to have two kinds: The destruction of steel ferrule and ball of pottery and porcelain. These two kinds all destroy a form for exhaustion. It is the dimension that exhaustion of ball of pottery and porcelain flakes only those who compare steel bearing is small. Did not wear away almost trace. Already had experiment and apply actually make clear, the destruction of ball bearing of pottery and porcelain basically behaves the exhaustion of the ferrule that it is steel to flake. Although nitrogen changes silicon to roll ministry of body happening end flakes, also won't expand quickly, its micro-crack is slow in movement of add of axial be adopted as heir to one's uncle only expand. Life of ball bearing of pottery and porcelain reckons type is: Lc=1[E ∝ (1+Ø)]3(1+F ∝ ) - 10/3z1/9(1+g)1/9Loc-10/921/9EocQ(5) expresses 1 experiment to use ball of Mm of diameter of ball of Mm of dimension of exterior of model of parameter of structure of ball bearing of pottery and porcelain to count × of B7007CY35 of material of ferrule of material of cage of material of ball of pottery and porcelain of primitive contact horn 62 × 147.

GCr15 of colophony of 1441615 ° HIPSN pursues the limited speed of model of main performance data that diagram of structure of unit of main shaft of 1 high speed expresses 2 report main shaft (A of lubricant means of KW of power of output of Mm of diameter of R/min) main shaft 30000354.

B of 5 oily mist 24000354.

In 5 fat type: F ∝ -- centrifugal force Q -- the osculatory bear Eo between scroll body and ferrule -- the model measures material flexibility from type (5) can discover, the factor that affects life of ball bearing of pottery and porcelain basically has: The centrifugal force of ① scroll body. When high speed moves, centrifugal force makes the body of load of bearing outer lane, rotate speed is higher, stress of outer lane contact is greater. 40% nitrogen changes silicon density is bearing steel, below identical rotate speed, can prevent bearing life effectively to reduce; The stretch model of ② material itself is measured. Nitrogen changes silicon flexibility modular amount is large, poisson comparing is small, make contact stress to greaten, the bearing life that runs to low speed is adverse; ③ advocate curvature and. Reduce ball of pottery and porcelain and ferrule contact point appropriately advocate curvature and, can improve the life of ball bearing of pottery and porcelain. 2 experiments study what this second experiment uses condition trying a face if parameter of ball bearing of pottery and porcelain expresses 1 to show. The data that uses ball of pottery and porcelain is HIPSN(heat to wait static press nitrogen to change silicon) , accuracy class is G3 class, the ball when assembling and ferrule are chosen subtly by plan value match. This bearing is used " small Zhumizhu " structure, use cage of outer lane light body. The place in the experiment has identical structural parameter with steel bearing and ball bearing of pottery and porcelain. The electric main shaft that experiment place uses has two kinds of type, it is A respectively model with B model. Structural diagram sees the graph is shown 1 times, bearing installs a form to be DBB. Express the 2 main performance data that are main shaft of two kinds of report. This experiment uses thermocouple to measure lukewarm law to measure the temperature rise of outer lane of bearing of main shaft front, before using PDD to measure main shaft of high speed report again, the oscillatory spectrum of back end, analyse two kinds of bearing to run to electric main shaft the influence of precision. The basis of high speed property that the experiment checks to analyse main shaft bearing as a result the curve of temperature rise character of the experimental data scale of main shaft of report of two kinds of high speed, by the graph 2, 3 visible, when rotate speed of A main shaft rises to ultimate 30000r/min by 2000r/min, steel bearing temperature rises to 35 ℃ by 4 ℃ ; When main shaft rotate speed rises to rotate speed 40000r/min by 2000r/min, temperature of ball bearing of pottery and porcelain rises to 43 ℃ by 35 ℃ , cross ball bearing of tall attaint pottery and porcelain to prevent temperature, stop to continue to lift the experiment of rotate speed. Show in the experiment, on level of identical temperature rise, when temperature rise is 35 ℃ , contain namely the rotate speed of electric main shaft of ball bearing of pottery and porcelain rises than steel bearing main shaft about 30% . In B report main shaft, apply ball bearing of pottery and porcelain, the actual rotate speed of electric main shaft makes an appointment with 30% ～ than using the limited speed when steel bearing to rise accordingly 50% . Analyse from afore-mentioned test results and theory knowable, ball bearing of pottery and porcelain compares steel bearing more apply to condition of high speed movement. The temperature rise of main shaft bearing by the graph 2 visible, when rotate speed of A main shaft is less than 15000r/min, the temperature rise of two kinds of bearing is basic and identical. When rotate speed is more than 15000r/min, the temperature rise of ball bearing of pottery and porcelain is apparent under steel bearing. What increase rate of steel bearing temperature rise compares ball bearing of pottery and porcelain is fast. By the graph 3 can see, main shaft of the overall change trend of the bearing temperature rise of B main shaft and A report is similar. But when main shaft rotate speed is inferior, the temperature rise of ball bearing of pottery and porcelain bearing of steel of summary prep above, temperature rise increase rate is minorrer than steel bearing. When rotate speed N>17000r/min, ability shows the character of small temperature rise of ball bearing of pottery and porcelain. The carry rotate speed of ball bearing of the pottery and porcelain below lubricant condition spends fat and the traversal speed of bearing of the steel when oily mist is lubricant comparatives. The discovery in the experiment, the temperature rise when ball bearing of B pottery and porcelain achieves hot balance and place need time, the temperature rise when achieving hot balance with ball bearing of A profiled bar and place need time close. The temperature rise character of main shaft of the 3 B of graph of temperature rise character of main shaft of graph 2 A report report pursues the temperature rise curve that the graph of temperature rise character that 4 report main shaft differs to fall for oily condition is shown 4 times is the main shaft bearing below condition of B different fuel delivery, see from which, the fuel delivery of demand of the place when lowest of ball bearing of pottery and porcelain under steel bearing, when and should be interrupted suddenly offerring oil, ball bearing of pottery and porcelain can keep the regular job of period of time, and steel bearing can burn out inside shorter time. By afore-mentioned knowable, lubricate with oily mist no matter or fat is lubricant, when high speed or lubricant inadequacy, the temperature rise of ball bearing of pottery and porcelain is less than steel bearing, the bearing of steel of life prep above of ball bearing of pottery and porcelain. The analysis thinks: The centrifugal power that ① produces as a result of ball of HIPSN pottery and porcelain and top moment of force are small, make ball bearing of pottery and porcelain sends quantity of heat little. ② bearing needs to be tightened beforehand when assemble, tighten force beforehand bigger, be out of shape and give out heat more, bearing temperature rise is sharper also. Below movement of bearing high speed, bearing susceptive always loses initial stage of pouch draw together to tighten force and bearing interior bear beforehand. In-house bear expands by centrifugal force and heat difference causes. When bearing works tighten force to be more than beforehand when assembling primitive tighten force beforehand, make attrition calorific thereby increase, bearing temperature rise increases. 25% what be bearing steel only as a result of the hot coefficient of expansion of material of HIPSN pottery and porcelain, reason rises when rotate speed when, the temperature rise value of ball bearing of pottery and porcelain is less than steel bearing much. The data makes clear, the inner ring material of ball bearing of pottery and porcelain introduces hot coefficient of expansion smaller than bearing steel the material such as steel of the stainless steel of 20% , cementite, can reduce the temperature rise of bearing effectively. Spectrum of main shaft vibration analyses the piezocrystal sensor that uses tall sensitivity, apply disperse teach to establish foliaceous principle to undertake signal exchanges computation, graph 5, 6 it is spectrum of vibration of main shaft of the A that uses PDB to be measured report. By the graph 5 visible, wave motion of acceleration of vibration of front of electric main shaft is bigger, the locomotive loss of accuracy that brings about electric main shaft, stiffness drops. By the graph 6 visible, the change of acceleration of vibration of front of electric main shaft of ball bearing of pottery and porcelain is dinky, the dynamic precision that main shaft runs is tall. Comparative main shaft of two sort report makes clear, ball bearing of use pottery and porcelain, what can reduce electric main shaft effectively is oscillatory, raise the locomotive precision of electric main shaft and stiffness. Graph 5 of vibration of front of main shaft of steel bearing report frequency pursues 6 of ball bearing of pottery and porcelain theory of above of 3 last words and experimental analysis make clear frequency of vibration of front of electric main shaft: Below same condition, ball bearing of pottery and porcelain compares steel bearing more apply to condition of high speed movement. The design that uses ball bearing of pottery and porcelain at unit of high speed main shaft, in making, can promote the limited speed of main shaft effectively, reduce the vibration of high speed main shaft, raise the locomotive precision of main shaft and stiffness. Ball bearing of applied pottery and porcelain can prolong the service life of electric main shaft, simplify to it the lubricant system of form a complete set. But should solve condition of low speed movement to fall, the issue with difference of stiffness of ball bearing of pottery and porcelain, small precision. CNC Milling CNC Machining