The development of sliding bearing of grinding spindle of supersonic speed grinding

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One, a bearing of overview grinder grinding spindle is the quality that affects grinding work, efficiency and stability main factor, generally speaking, bearing of grinder grinding spindle has scroll bearing and sliding bearing 2 kinds big. Groovy grinding speed (ν ＝ 35 ' M /s) , main shaft sliding bearing already developed quite high level, have dynamic pressure bearing, static press bearing and activity to press bearing, its research work already had 10 years of several histories, its coach theory is Reynolds equation basically, assume in Reynolds equation attrib border condition issues computation, research to wait (static press bearing to have computational method additionally) . But to emery wheel linear velocity ν > when 80m /S, afore-mentioned sliding bearing are competent harder, especially at present car camshaft, crankshaft is reached exceed grinding of qualitative roller of hard steel material, use CBN emery wheel (cubic nitrogen changes boracic abrasive) undertake high speed grinding, abroad uses high speed generally to roll bearing is propped up as main shaft. But because scroll bearing useful life is brief, need to often change in long-term grinding job bearing. The author carries out experience according to what come for years, think to develop high speed sliding bearing to must overcome 2 catastrophe to inscribe. 1. Sliding bearing of calorific high speed is calorific and main have 2 respects factor. Because get,be above all what cause by fluid viscosity is small the action of mutual shearing force when flowing because of the element, rotate speed is higher, shearing force effect is bigger, namely inside friction work is greater, amount of generation heat energy is larger. This part heat energy basically relies on technology of aspic of oily liquid cooling to solve now. It is attrition of sealing ring of main shaft journal is caused on the other hand. Rate is higher, heat of sealing ring attrition is bigger, and sealing ring itself has the restriction that gets used to rotate speed limits. In practice, sealing ring still can be on main shaft neck grind a groove to come, make bearing system invalidation, for this, should idea purify sealing ring. 2. Break firm about oily film oscillation, half fast eddy is moved, synchronous eddy is moved wait for a problem. British Baweier has a lot of authority to study theory, allegedly if of inherent and oscillatory frequency of the axis and journal speed than be 1 ／ 2, amplitude will pass big and destroy oily film. Point out at the same time in any given below eccentricity, turbulence does not have too much influence to stability it seems that, same, british Pingkesi points out: When the speed in the axis can drive a fluid to circling the pressure that clearance flows and keeps driving force of a generation to distributing, this speed decides the frequency that uses for eddy. The force place that by bearing oil film produces causes fluid motivation instability, right now the displacement of countershaft comes say, its way drives an axis to undertake eddy is moved. The author discovers a kind of circumstance however in practice: Be not the vibration in system of the bearing inside limits of whole rotate speed (outside not have load circumstance falls) increase as heighten of main shaft rotate speed. It is in fact in long-term and many production practice, the author thinks, research misses firm issue, should study namely small the influence because of active force, want to consider the macroscopical effect of bearing system at the same time again. Add plane to stop to traditional 2 cylinder journal bearing the bearing system that turns bearing combination, the high speed when its move and low speed can produce disparate situation. Can say even same kind of structure, its rotate speed limits can be quite finite (take no account of sealing ring element) . To common oil pocket, the boundary line side its is common as parallel as bearing axes line, if this phenomenon is used small because unit is oily for, meeting and line of axes of the borderline side oil pocket and bearing place its result what one helix angle arises a result to differ very few, but be not in practice such. Graph the line of 1 oil pocket border that is a tradition and the bearing with axes parallel line, rotate in bearing when main shaft when, oo of main shaft axes and Dd of boundary line of boundary of oil pocket axial are parallel, main shaft every rotate a week, have 6 oil pocket namely force of dynamic pressure of cost of constant of 6 δ area; β of likewise initiative horn also is worth for constant (graph 1 - B) . In the graph 2 - in A, a ' - A ' with A" one A" is in either is sectional incision, get same picture 1 - B. Force of dynamic pressure of the oil pocket inside bearing is ordinal 6: "O of → of O → great value " periodic, and graph 2 for border of oil pocket axial effect of helix angle of line and axes line clip pursues. Set " Oo " for main shaft some section line, with rotate speed N ordinal had turned oil pocket 1, 2, 3, 4 when allow to cut one sectional, can get a picture 2 - what B differs is different and sectional CDGC, position of angle of β , δ is different, that is to say, the either with respect to bearing axial is sectional inside ordinal still have area of force of 4 δ dynamic pressure, still depend on have 4: "O of → of O → great value " change. But for whole bearing nonexistent already region of strength of some dynamic pressure, also do not have " O of → of O → great value " changed. Nextpage 　 2, fast activity presses new-style freeboard fast activity presses the new-style freeboard that the author develops axial GL-01 　 recently axial GL-01, if pursue,3 are shown. This is the bearing system of oil pocket of helix of a kind of inner cone. Leave out traditional plane stops push bearing, also do not have sealing ring. Ø120mm of diameter of main shaft main aspects, use CBN emery wheel, Ø500mm of emery wheel diameter, 12000r /min of ＝ of Ф of main shaft rotate speed, emery wheel linear velocity υ =370m/s, exceed velocity of sound. 1.

CDFE is oil pocket of helix of actual taper seat here, CDGC of dotted line part ' it is oil pocket of fictitious taper seat, DD ' with axes line QQ ' parallel, DG and DD included angle are conic half horn A, DG and DD ' included angle is helix angle β , FA seals fat face for radial. Fictitious DD ' give priority to line of axial some section, edge N direction rotates, nod from oil pocket A ordinal had turned E of → of F of D → , cut cover line to take a person partly when main shaft either apparently when some oil pocket, the another part of this section line is moving stage by stage a last oil pocket, this is helix oil pocket. Because bearing of helix oil pocket suffers load is tropism of balanced not in the proper way, main shaft rotates will be extremely smooth. Speed of main shaft movement does not accept any restriction inside quite big range. 2.

Because be conic bearing, oily film is opposite the law of the surface of main shaft to turn over force to decompose Sin of law of F of radial component of force α of Cos of α and law of F of axial component of force; The existence of axial component of force makes plane does not need to stop in bearing system the interpose person that turns bearing (conic of course bearing needs to be used in couples) , the structure is simple. More important is conic bearing it is natural need not journal seal ring seals oily bearing system. No matter main shaft is in dormant or low speed or high speed rotate condition need not seal ring. Can make following prooves: The fluid that set oil from Z axis to when pouring out of bearing, 2 sectional Zl, Z2 is taken in Z axis random, take 2 zonule in place of Zl, Z2 Z2 of △ Zl, △ , beg a Zl respectively sectional with the cubage Vz1 with sectional Z2 and Vz2. Flow to Z2 area from Zl area when oily fluid when, as a result of cannot the cubage of cram Z2 area, need to complement again from Z1 area one part oily fluid makes increment Z, so ordinal analogize, when oily fluid from Z axis to when pouring out of bearing, oily fluid will have increment of in succession add, have one acceleration namely, direction points to Z axis to, make oily fluid pours out of Z axis quickly to (the fluid in practice pours out of bearing into eject shape, is not traditional and columnar bearing in that way " easy " the ground is poured out of) . Oily fluid goes against acceleration direction and Z axis impossibly to lose to pour out of bearing. So this is the bearing system that does not have seal ring. 3, apply Shanghai China bear bearing of film of development of machine tool limited company is old already, recently, development goes sliding bearing of high speed of a kind of high accuracy, installation is on the MK8332 camshaft grinder of factory of Shanghai machine tool, linear velocity of emery wheel grinding can be achieved 200 and S, prolonged service life. The sliding bearing of high accuracy of this high speed that our company design is used first without sealing ring, and rotate to prevent high speed break firm, used technology of helix oil pocket, make main shaft rotate speed still behaves an extreme when be as high as above of L0000r / Min smooth. Develop this bearing circumstance introduction to be as follows now: Nextpage 　 　 1. 　 of fundamental condition data (L) bearing: Type: Activity of a flight of stairs presses material of 　 of 　 of 　 of high speed bearing: ZQSn6 - 6 - oil pocket of 　 of 　 of 　 of 3 　 : Shallow oil pocket of 4 helix shape, single accent is deep 0.

02 at 0.

　 of 　 of 　 of 030mm 　 stops push: Without stop turn ring, stop by taper seat push (bearing structure shows 4 times like the graph) 　 　 (2) main shaft: Material: 38CrMoA12, nitrogen converts steel, t - D3.

0 - clearance of 　 of 　 of 　 of 900 　 : 0.

040 - 0.

Precision of circumgyrate of 　 of 　 of 　 of 045mm 　 : Cone is made jumpy 1.

Diameter of 　 of 　 of 　 of 　 of 0 μ M: 　 of φ 120mm 　 (3) installation and working overview: Around bearing is symmetrical and conic bearing. First will before inside housing of bearing pressing person, extend main shaft front person bearing again, next main shaft of ring of the aperture inside bearing. Person of the round housing that press a person comes outside beforehand position office stops. (when the system is being installed need not screw) when main shaft system is working, as a result of main shaft two end are two taper seat (symmetrical) , radial and axial bear at the same time laden effect, and rely on to stop traditionally no longer push annulus to stop push. (4) offer oil: Oily fluid is oil of 2# main shaft; Oil pressure is oil feeding reservoirs of 15L/min 　 to have refrigeration and 　 of nitrogen accumulator device for discharge of 25kg/c ㎡; (5) start: Main shaft drive does not have leather belt annulus for electric main shaft, electric main shaft has 　 of Nmax3OkW 　 of 　 of Nmax16000r/min of 　 of 　 of cooling device 　 likewise (6) main shaft dynamic balancing: Main shaft and in advance of electric machinery rotor beforehand N = 1000r/min of rotate speed of dynamic balancing dynamic balancing, dynamic balancing value is O - 0.

6 grams 　 (7) 500mm of φ of ＝ of D1 of emery wheel diameter, 75Omm of φ of D2 ＝ , material: CBN (cubic nitrogen changes boron) 　 　 2. Detect data: (L) T of temperature rise △ : Nl = 4500, ℃ of 25 of △ T ≤ (℃ of room temperature 6 did not start refrigeration) 8000r/min of ＜ of N of 4500r/min ＜ , ℃ of 33 of △ T ≤ (℃ of room temperature 6, the refrigeration that start) 120O0r/min of ＜ of N of 8000r/min ＜ , ℃ of 67 of △ T ≤ (℃ of room temperature 6, the refrigeration that start) (2) precision of circumgyrate of main shaft radial: Et=0.

0015mm (be caused by of error of oily film leveling) (3) precision of circumgyrate of main shaft axial: En=0.

002mm (4) M of μ of 6=66kgf/l of main shaft static stiffness (㎡ of oil pressure 25kgf/c) (5) main shaft answers rotational stiffness: 　 of 　 of 　 of 　 of 　 of 　 of 　 of 　 of 　 of M of μ of =2O0kgf/l of δ of N=4000r/min of 　 of 　 of 　 of 　 of 　 of 　 of 　 of 　 of 　 of 　 of 　 of M of 100kgf/1 μ of ＝ of N=1500r/min δ does not have a value basically when N ＞ 5000min δ (inside 200kg) (6) electric machinery electric current: Resistor of electric machinery three-phase all is 0.

　 of 　 of 　 of 　 of 　 of 　 of 　 of 　 of 　 of 1 Ω 　 becomes 　 of 　 of 　 of 　 of 　 of 　 of 　 of 　 of 　 of 　 of N = 2000r/min loses person electricity: 7.

8A 7.

1A 7.

　 of 　 of 　 of 　 of 　 of 　 of 　 of 　 of 　 of 6A 　 exports electricity: 1.

8A 4.

8A 4.

　 of 　 of 　 of 　 of 　 of 　 of 　 of 　 of 　 of OA 　 becomes 　 of 　 of 　 of 　 of 　 of 　 of 　 of 　 of 　 of 　 of N = 450Or/min loses person electricity: 18.

2A 18A 18.

　 of 　 of 　 of 　 of 　 of 　 of 　 of 　 of 　 of 1A 　 exports electricity: 11.

6A 14.

1A 12.

5A (7) main shaft is actual and highest rotate speed: 　 of Nmax=12500r/min 　 3. Result: Main shaft is highest linear velocity amounts to Vmax=78.

500 emery wheel of φ of 　 of 5m/s 　 　 Vmax= 490m/s (of 750 emery wheel exceeds φ of 　 of Vmax=32lm/s 　 　 sonic) 　 4, brief summary 　 1, because be conic bearing, the force on the lube small unit of the action force department on lubricating fluid small unit and columnar bearing is different, become apparently conic when half horn A=O, 2 kinds of force are consistent. 2, as a result of conic in Z axial, bearing diameter D is not one constant. (and D of traditional bearing diameter is constant) , such fluids are in X to the linear function that VX is Z axis. Additional, because be conic helix oil pocket, make actual oil pocket radial the function that Vx of velocity of flow and Vz of axial velocity of flow become Z rod (nonlinear function) . To a few kinds of afore-mentioned circumstances, the author has not build digital model. 3, because conic bearing oily film bears the weight of,force cent becomes radial and axial 2 heft, and this kinds of bearing is used in couples. The component of force of a pair of axial that appears in bearing system, become what axial change moves to stop actually thrust. The place on put together is narrated, the author thinks a kind of any sliding bearing, after its design computation, will be made, craft a variety of limitation that wait, scope of application also will be restricted. CNC Milling