Hemispherical fluid bearing
The present invention relates to a kind of bearing, more particularly, is a kind of hemispherical fluid bearing.
Usually, FDB is used to support the object of high speed rotating.Traditional contact bearing such as ball bearing or roller bearing can produce violent vibration and noise under situation about running up, and rotation is unstable.In contrast, FDB is with non-contacting form high speed rotating, fewer vibrations and spin stabilization.Therefore, FDB can be applied in the spindle drive motor of necessary atwirl hard disk drive, or uses in the multilist face mirror drive motor of the rotation in laser printer or laser scanner.
Fig. 1 is the sectional view of traditional hemisphere bearing, and it is a FDB.As shown, traditional hemispherical fluid bearing comprises a upper inner ring 20 and a lower inner ring 30, and they respectively have an exterior semi-spherical surface, and they are fixed on the axle 10 of a motor mutually Face to face; One is fixed on an outer shroud 50 in the bearing housing 40; A ring 60 is used to keep upper inner ring 20 and lower inner ring 30 not to break away from from axle 10; A pad 70, it is arranged between upper inner ring 20 and the lower inner ring 30, is used to remain between outer shroud 50 and the upper inner ring 20 and gap between outer shroud 50 and the lower inner ring 30.
Outer shroud 50 supporting upper inner ring 20 and lower inner rings 30 are so that they can revolve.Owing to use lubricant oil filling gap between outer shroud 50 and interior ring 20 and 30, and produce fluid friction betwixt, upper inner ring 20 and lower inner ring 30 can not have rotation contiguously with outer shroud 50.Therefore, use the motor of this hemispherical fluid bearing can not produce vibration and its rotation is stable.
Yet traditional hemispherical fluid bearing demonstrates an obvious defects, promptly can make the contact surface wearing and tearing of outer shroud 50 and interior ring 20 and 30 when motor starting with when stopping.In other words, between outer shroud 50 and upper inner ring 20, and between outer shroud 50 and the lower inner ring 30 critical velocity or under produce solid friction, quickened wearing and tearing like this, the result reduces the lifetime of hemispherical fluid bearing.
The purpose of this invention is to provide a kind of hemispherical fluid bearing that can reduce the wearing and tearing that cause by solid friction effectively.
In order to achieve the above object, the invention provides a kind of hemispherical fluid bearing, comprise ring in a pair, ring has the outer lubricated surface of a sphere in each, they are fixed on one with facing one another, also comprise an outer shroud, it has a lubricated surface corresponding to the lubricated surface of ring in described, be used to support the rotation of described interior ring, it is characterized by, ring and described outer shroud had the first film coating of a titanium that forms at least one was described on its lubricated surface, and formed second film coating of a diamond-like-carbon on described the first film coating.Form a predetermined groove on second film coating, it extends to the first film coating.The first film coating is 5-20 μ m, and second film coating is 5-10 μ m.
Above-mentioned purpose of the present invention and advantage will be more obvious to the description of the details of preferred embodiment in conjunction with the drawings, wherein:
Fig. 1 is the sectional view of traditional hemispherical fluid bearing;
Fig. 2 is the sectional view according to hemispherical fluid bearing of the present invention;
Fig. 3 is the sectional view along the A-A line of Fig. 2.
Referring to Fig. 2 and 3, hemispherical fluid bearing according to the present invention comprises a upper inner ring 20 and a lower inner ring 30, ring respectively has a semispherical surface in each, they face one another face ground and are fixed on the axle 10 of motor, also have one and be fixed on an outer shroud 50 in the bearing housing 40, be used to support upper inner ring 20 and lower inner ring 30, so that they can rotate, a ring 60 that is used to keep upper inner ring 20 and lower inner ring 30 not to break away from from axle 10, a pad 70, it is arranged between upper inner ring 20 and the lower inner ring 30, is used to keep between outer shroud 50 and the upper inner ring 20, and the gap between outer shroud 50 and the lower inner ring 30.At this, ring 60 can be installed or and axle 60 screw thread combinations forcefully.
Upper inner ring 20 and lower inner ring 30 mainly formed by high carbon steel or WCo and has thick titanium (Ti) film 21 of 5-20 μ m.Similarly, the lubricated surface of outer shroud 50 is mainly formed by high carbon steel or WCo and the thick titanium film coating 51 of 5-20 μ m is arranged. Film coating 21 and 51 can be replaced by the ceramic membrane coating, for example, and Al
2O
3Film coating.In addition, upper inner ring 20, lower inner ring 30 and outer shroud 50 can be formed by pottery entirely.
Film coating is used to alleviate between outer shroud 50 and the upper inner ring 20, and the wearing and tearing between outer shroud 50 and the lower inner ring 30, and therebetween solid friction produces in critical velocity or when being lower than this speed by motor starting or when stopping in these wearing and tearing.
On the other hand, in order further to reduce the wearing and tearing that cause by solid friction, on the titanium film 21 of upper inner ring 20 and lower inner ring 30, scribble diamond-like-carbon (DLC) coating of 5-10 μ m.Because DLC film coating 22 has the coefficient of linear expansion similar to titanium film coating 21, so do not worry peeling off or the gap changes.In addition, the former has so more effectively reduced the influence of solid friction than latter's rub resistance more.
Be formed with a groove 23 on DLC film coating 22, groove 23 can arrive titanium film coating 21 by DLC film coating 22 according to the thickness of DLC film coating 22.Groove 23 is by produce oil pressure or air pressure lifting upper inner ring 20 and lower inner ring 30 when inside and outside ring rotates, away from outer shroud 50.
In addition, DLC film coating 22 and groove 23 are provided for outer shroud 50.
The embodiment of a method that is used to make above-mentioned hemispherical fluid bearing will be described in detail belows.Mainly to not sphericity 0.15-0.25 μ m is arranged, and their spherical surface scribbles the thick titanium film of 5-20 μ m by mechanical lapping for upper inner ring 20 that is formed by high carbon steel or WCo and lower inner ring 30.Then, the thick DLC film of 5-10 μ m is coated on the titanium film.
A kind of titanium ion bundle injection method or titanium gas deposition method can be used for the coated titanium film.The titanium film can be replaced with same method by ceramic membrane.
The lubricated surface of outer shroud 50 scribbles 5-20 μ m thick titanium film or ceramic membrane.
After this, by chemical corrosion method or discharge mechanical means groove 23 is formed on the DLC film 22.
As mentioned above, can stop effectively according to hemispherical fluid bearing of the present invention by the wearing and tearing that solid friction produced between interior ring and the outer shroud.Therefore, its life-span is rise-to stop for 500,000 times approximately, and traditional bearing has 100, and 000-200 rise-stops for 000 time.