DE19950463B4 - Method for producing a hydrodynamic plain bearing for a spindle motor and a hydrodynamic plain bearing produced using the method - Google Patents

Abstract

Method for producing a hydrodynamic plain bearing for a spindle motor for the precise rotation of an electromotively driven rotor rotating at high speed relative to a fixed stator, consisting of at least two essentially rotationally symmetrical concentrically arranged parts which are operatively connected to one another, such that the outer envelope surface of the inner part with the inner envelope surface of the outer part at least in regions forms a thin concentric and / or coaxial gap, at least one of the envelope surfaces - preferably that of the rotating part - being provided with a three-dimensional structure for generating the hydrodynamic pressure, characterized in that To produce the three-dimensional structure (8), the surface (2) of the bearing is first provided with a uniform, re-removable application layer (3) of constant thickness, and then that which is desired e structure is at least partially removed by partial removal of the application layer (3) by means of focused radiation (4).

Description

The invention relates to a method for the production of a hydrodynamic plain bearing for one Spindle motor according to the preamble of claim 1. Such Camps for fast spinning disk space used. So it's about to miniature bearings for use at high speeds.

The present invention is concerned with the simplified manufacture of a fluid bearing for such Spindle motors. It is known here to have a fluid bearing liquid or a gaseous one To operate medium for what generally the term "fluid" is used.

So far it is known, the bearing surfaces of such To process fluid bearings in a relatively complex process, in particular one or more lapping processes are used or - if so it is a hollow bearing, a corresponding honing process used.

With such fluid bearings, it is known to introduce structures into the bearing surfaces in order to ensure the bearing properties of these bearings. Such a plain bearing is from the post-published DE 198 23 630 A1 known. Structures of this type are introduced by mechanical removal of material from the precisely machined surface or by plastic molding, so that the material in the area of the structure is displaced by displacement processes.

Disadvantage of mechanical machining processes is that because of of repression of material or mechanical abrasion it also leads to material accretion comes in the machined edge area, these upgrades then have to be removed relatively expensive.

The removed structures must be in the accuracy of about 1 micron, which leads to the need leads, that corresponding material poses need to be removed because they affect accuracy.

The post-processing steps for such a mechanical machined fluid bearings are relatively expensive, difficult and increase also the manufacturing costs of this fluid bearing.

The DE 44 03 340 A1 discloses a method of making micro nozzles in a surface of an aerostatic bearing. Here, holes are made in a compressed and / or coated sintered material by means of a laser.

From the DE 198 09 367 A1 A method for the fine machining of piston raceways of, for example, internal combustion engines is known, in which indentations are irregularly distributed in the surface of the piston raceway by means of laser or water jet. Oil droplets can be deposited in these depressions in order to improve lubrication of the piston during operation.

A similar procedure is in the DE 43 16 012 A1 described. Grooves or grooves are made in a workpiece surface, for example a piston raceway, by means of laser beam treatment.

Gregory's article, Axel R .: “Basis of new Manufacturing processes " In: Technische Rundschau 23/91, pp. 62-65, generally concerns the Material processing using laser beams, and describes under also targeted removal of material with a laser beam, comparable to the conventional one milling, to work out a desired one Structure in the material surface.

A targeted and highly precise processing of running surfaces a hydrodynamic plain bearing for the production of the structures described above let yourself not easily achieved with the known methods.

The object of the invention is therefore is based on a method for producing a fluid bearing for spindle motors so that the process executed much easier can be so that the Manufacturing costs of a fluid bearing manufactured with it significantly be reduced.

Likewise, the invention has the Task given a fluid bearing manufactured by the process for spindle motors preferably inexpensive, simple and provide reliable training.

To solve the task the method is characterized by the technical teaching of claim 1. A hydrodynamic plain bearing manufactured using the process is specified in claim 14.

Essential features of the invention are the following process steps:

• 1. Highly precise machining of the bearing surfaces Fluid bearing.
• 2. Coating the high-precision machined bearing surfaces of the Fluid bearing with an application layer.
• 3. Introduce the desired Storage or surface structures through controlled, controlled removal of the application layer through an energetic beam.

Essential feature of the method according to the invention is that one the bearing structures no longer through mechanical processing brings in, but that one to the precise machined surface of the camp first applies an essentially self-contained coating layer and this application layer with the desired surface structure of the later Bearing provides, the surface structure by a partially attacking removal process is achieved.

According to the invention, spatially designed storage areas that in particular in the interior of a hollow cylinder, by means of a Abtragstrahles are processed so that they have the desired contours for the Have storage. The structure can also be on the cylindrical Counterpart applied his.

The camp is direct or indirect formed on the rotor. The application layer can be applied in various ways Processes take place, in particular an electrolytic one Application preferred, i.e. H. in the case of an aluminum one Rotors can apply an anodized coating in a wet chemical Methods are applied, the in a manner known per se Anodized layer grows on both the surface of the rotor itself but also partially extends into the surface.

However, there are other order procedures provided, in particular the application of an application layer by conventional coating methods, such as B. application by means of electron beams (sputtering) or other, known per se, order processes. To sum up: the process according to the invention Play something like this.

The invention can be used in hydrodynamic plain bearings, in particular hydrodynamic fluid or gas bearings for high-precision rotation of an electric motor driven, at high speed relative to a fixed stator rotating rotor (preferably as drive for hard drives in HDDs) Find use. These essentially consist of at least two rotationally symmetrical concentrically arranged parts that are together are in operative connection such that the outer envelope surface of the inner part with the inner envelope surface of the outer part at least in some areas a thin one concentric and / or coaxial gap forms, at least one of the envelope surfaces - preferably that of the rotating part - with a three-dimensional structure to create the hydrodynamic Pressure is provided, which is used to produce the three-dimensional Structure first the surface the by known mechanical processing methods such Turning, milling, Grinding or similar manufactured part with an even, removable layer constant thickness and then the desired structure by partial removal of the layer, preferably by removal is removed again by means of laser, the depth of the structure thus produced corresponds essentially to the thickness of the redetachable layer. The depth of the structure can also be less than the thickness the applied layer. Both the degree of absorption should be advantageous the layer surface on the one hand, as well as the degree of reflection of the exposed surface be high in terms of the laser light used.

Furthermore, the surface of the re-wearable layer to be particularly wear-resistant and a low Have a coefficient of friction.

In a preferred embodiment the redetachable layer consists of a DLC layer [DLC stands for Diamond Like Carbon], one using hydrocarbon gas resulting, diamond-like layer with predominantly tetrahedral crystal structure. The deposition on the surface is carried out by methods known per se, such as. B. Plasma CVD process.

Therefore, as a material for the application layer all Materials claimed as essential to the invention for a beam-bound Removal processes are suitable.

However, the method according to the invention is not limited to removal of the application layer by means of a laser. It can other energetic ablation procedures can also be used, such as z. B. removal by means of an electron beam, a high-energy X-ray beam, an ion beam and the like.

The thickness of the application layer is preferred here about 3 to 15 μm.

The advantage of the method according to the invention is that with the use of a high energy abrasive jet to make it easier Way is possible not just flat storage areas to edit, but also spatial Storage areas, which are particularly in the interior of a hollow cylinder, what with other mechanical processing methods very difficult and time consuming possible was.

This also applies to spherical bearings, where also on a spherically curved surface the structures can be introduced using the removal process. Mechanically it was very difficult to do.

The invention is not limited to one limited special shape of a fluid bearing; it can all known forms of a Fluid bearings are processed in order to maintain the desired surface structures. Likewise, different Application procedure applied to apply the application layer like e.g. Sputtering, anodizing, electrolysis and the like more.

The subject of the present invention arises not only from the subject of the individual claims, but also from the combination of the individual claims. All in the documentation, including the summary, Disclosed information and features, especially those shown in the drawings spatial Education are claimed as essential to the invention, insofar as they individually or in combination compared to the prior art are.

In the following, the invention will be explained in more detail with reference to drawings showing several possible embodiments. Further features and advantages of the invention which are essential to the invention are derived from the drawings and their description out.

Show it:

1 : Much enlarged section through a rotor with an application layer in two different process states;

2 : An air bearing with a rotor behind 1 ;

3 : Another embodiment of a fluid bearing.

In 1 is a schematic and greatly enlarged a rotor 1 shown, initially as from the left part of the illustration 1 evidently has a smooth and precisely machined surface. It should be noted here that the representations in the figures are not necessarily true to scale, but that the explanations merely reflect basic representations.

In a further process step, this precisely machined surface is applied 2 an order shift 3 applied, which is preferably applied as an anodized layer. The application as an anodized layer in an electrochemical process has the. Advantage that the layer thickness (depth 24 ) this order shift 3 over the surface 2 of the rotor 1 can be controlled relatively precisely, so that an application of an anodized layer of a subsequent application z. B. is significantly superior to a powder coating. It is not essential to the invention like this anodized layer (application layer 3 ) is applied.

So after the job shift 3 is applied, it forms the later storage surface on its surface 12 ,

Of course, this storage surface 12 can be treated afterwards by additional hardening and coating processes.

In the illustration on the right 1 Another process step is shown, in which by means of a high-energy beam 4 (e.g. a laser beam) recesses 5 in the order shift 3 be incorporated.

These recesses are due to the beam geometry 5 slightly conical and open at the top.

However, this remains indifferent to the present invention, ie the cross-sectional shape of the recesses 5 is arbitrary here and in particular mutually parallel walls of the recesses 5 prefers.

By means of the beam 4 becomes the job shift 3 So locally removed, so that the recesses 5 form.

It is preferred if the depth 24 of the recesses 5 to the surface 2 of the rotor 1 enough. Here comes the reflective surface 2 of the rotor 1 at the bottom 25 the recess 5 to the surface, in which case the removal process is ended.

In 2 is a fluid bearing as an example 13 shown, which consists of a rotor 1 exists in the axis of rotation 7 is rotatable and, for example. In the direction of rotation 17 in a recess of a fixed stator 6 rotates.

To form a radial bearing, channels can be arranged opposite each other 9 a print medium 10 be introduced, which is in the direction of the arrow 11 on the bearing surfaces 12 of the rotor 1 distributed.

The aforementioned recesses 5 now form structures 8th on the bearing surface 12 of the rotor 1 and are generated using the previously described method.

3 shows another embodiment of a fluid bearing in an application as a spindle bearing for hard disk storage.

Here is the fluid bearing 14 from a fixed shaft 15 that on a base plate 16 is attached. The fixed wave 15 goes into a shaft flange at its upper end 18 enlarged diameter over.

The rotor 1 is as a body with one to the axis of rotation 7 concentric opening, the opening diameter is smaller in the lower region and thereby a projection 20 ' forms. This projection can be an integral part of the rotor 1 or as a rotor sleeve additionally introduced into a rotor opening with the same opening diameter throughout 20 be designed.

There are now the bearing surfaces for a radial bearing 21 and for axial bearings 22 . 23 in the form of recesses 5 again arranged on the rotating parts, which in turn changes the structures 8th train, which were produced with the ablation process described above.

Advantage of this spindle bearing 3 is that both a radial and two axial bearings 22 . 23 by simply making the recesses 5 are provided on the rotating bearing surfaces and that a spindle bearing with high load-bearing capacity and high speeds is hereby created.

1.

rotor

Second

surface

Third

application layer

4th

beam

5th

recess

6th

stator

7th

axis of rotation

8th.

structure

9th

channel

10th

print media

11th

arrow

12th

bearing surface

13th

fluid bearing

14th

fluid bearing

15th

wave

16th

baseplate

17th

direction of rotation

18th

shaft flange

19th

recess

20th

rotor sleeve

20 '

head Start (Rotor)

21st

radial camp

22nd

axial camp

23rd

axial camp

24th

depth

25th

reason

Claims (14)

Method for producing a hydrodynamic plain bearing for a spindle motor for the precise rotation of an electromotively driven rotor rotating at high speed relative to a fixed stator, consisting of at least two essentially rotationally symmetrical concentrically arranged parts which are operatively connected to one another, such that the outer envelope surface of the inner part with the inner envelope surface of the outer part at least in regions forms a thin concentric and / or coaxial gap, at least one of the envelope surfaces - preferably that of the rotating part - being provided with a three-dimensional structure for generating the hydrodynamic pressure, characterized in that to produce the three-dimensional structure ( 8th ) first the surface ( 2 ) of the warehouse with an even, re-removable application layer ( 3 ) of constant thickness, and that the desired structure is then removed by partially removing the application layer ( 3 ) by means of focused radiation ( 4 ) is at least partially removed. A method according to claim 1, characterized in that the depth of the structure thus produced ( 8th ) essentially the thickness of the re-removable application layer ( 3 ) corresponds. A method according to claim 1, characterized in that the depth of the structure thus produced ( 8th ) smaller than the order layer ( 3 ) is. Method according to one of the preceding claims, characterized in that spatially designed bearing surfaces, which are in particular in the interior of a hollow cylinder, by means of a removal jet ( 4 ) are processed so that they have the desired contours for storage. Method according to one of the preceding claims, characterized in that the structures for storage by means of the removal jet (on spherical bearings with spherically curved surfaces) 4 ) can be introduced. Method according to one of the preceding claims, characterized in that locally controlled removal of the application layer ( 3 ) by a laser beam with the introduction of the desired bearing structures. Method according to one of the preceding claims, characterized in that locally controlled removal of the application layer ( 3 ) by an electron beam with the introduction of the desired bearing structures. Method according to one of the preceding claims; characterized in that locally controlled removal of the application layer ( 3 ) by an ion beam with the introduction of the desired bearing structures. Method according to one of the preceding claims, characterized in that locally controlled removal of the application layer ( 3 ) by an X-ray with the introduction of the desired storage structures. Method according to one of the preceding claims, characterized characterized that the applied layer partially precise and / or by the selected removal method is more economical to process than the original base material with regard to the surface structure to be introduced. Method according to one of the preceding claims, characterized in that the application layer ( 3 ) is applied by anodizing. Method according to one of the preceding claims, characterized in that the application layer ( 3 ) is applied by sputtering. Method according to one of the preceding claims, characterized in that the application layer ( 3 ) is applied by electrolysis. Hydrodynamic plain bearing for a spindle motor, produced by the method of claims 1 to 13, in which at least one of the surfaces ( 2 ) of the plain bearing with a three-dimensional structure ( 8th ) is provided for generating the hydrodynamic pressure, characterized in that the surface ( 2 ) with an even, removable coating ( 3 ) of constant thickness, the three-dimensional structure ( 8th ) by partially removing the coating ( 3 ) by means of focused radiation ( 4 ) is formed.