DE102014114326A1 - Method for producing a rotor or stator disk for a vacuum pump and rotor or stator disk for a vacuum pump - Google Patents

Abstract

The invention relates to a method for producing a rotor or stator disk for a vacuum pump and a rotor or stator disk for a vacuum pump, wherein the rotor or stator is made of a blank of solid material by sawing inclined to a disk plane channels in which at least one disc surface of the blank is formed radially symmetrically curved before the sawing of the channels.

Description

The invention relates to a method for producing a rotor or stator disk for a vacuum pump as well as a rotor or stator disk for a vacuum pump.

Several successful types of molecular pumps are based on disks in which blades are mounted on a support ring which sits on a high speed shaft. Examples include the so-called turbomolecular pumps, in which alternate rotor and stator discs. The geometry of the blades has a major impact on the performance and life of the pump.

Various types of rotor or stator disks are known in the art. A common design consists of sheet metal, which is stamped during manufacture so that a round disc with radial slots is formed, the radial slots are provided only over an outer part. The part between the slots is bent over, that is exposed out of the window plane, so that blades are formed. This solution is for example in the DE-OS 100 52 637 shown.

The prior art ( DE 297 15 035 U1 ) includes a friction vacuum pump in which stator and rotor blades are formed. The stator blades are formed of sheet metal, which are correspondingly limited during manufacture, so that from the inside to the outside, the blades have an increasing height. The rotor blades are adjusted accordingly, so that the gaps between the blades are constant and as small as possible.

The cupping of the blades has the disadvantage that a material change is brought about, which considerably limits the stability of the blades.

In particular, in vacuum pumps, such as turbomolecular pumps with very high speeds thus often cause problems, since the sheets are made very thin. As a result, the discs can not be exposed to rapid rotations because the material load on the blade ground would be too high.

From practice it is also known that the blade angle is varied in order to set the degree of overlap between the individual blades and thus the so-called optical tightness in rotor or stator discs. The disc surfaces are aligned plane-parallel to each other. The technical possibilities for production limit the variation of the blade angle in some cases, so that the blades overlap again at their inner diameter and are no longer optically dense at the outer diameter. The disadvantage here is that in order to achieve an optical seal on the outer diameter of the disc, the blade angle outside must be chosen very flat, which reduces the open structure and thus limits the pumping speed.

The usual solution known from practice, which produce discs of solid material by sawing inclined to the disc plane channels, has the disadvantage that the manufacturable geometries are limited by the tools. For example, it is difficult to create a steeper angle of attack on the blade root, because then the saw comes into contact with the outer part of the blade.

The technical problem underlying the invention is to provide a method for producing a rotor or stator, with the optimization of the overlap of the blades and thus an improvement of the compression and the pumping speed is possible. In addition, a rotor or stator with a very good pumping speed and a very good compression should be specified.

This technical problem is solved by a method having the features of claim 1 and a rotor or stator with the features of claim 10.

The inventive method for producing a rotor or stator for a vacuum pump, wherein the rotor or stator is made of a blank of solid material by sawing inclined to a disc plane channels is characterized in that at least one disc surface of the blank in front of the Sawing the channels is formed radially symmetrically curved.

By this design, it is possible to perform, for example, the rotor or stator disc convex-spherical. Due to the radially symmetric curvature, it is possible to optimize the overlap of the blades. The overlap can be both positive, it can be "zero", that is seen in the axial direction, if the disks are just optically dense, they can also be negative, that is, when viewed axially, there is a defined gap between the blades.

According to an advantageous embodiment of the invention, both disc surfaces are formed radially symmetrically curved. This embodiment has the advantage that the blade geometry of the stator or rotor disk can be designed according to the required requirements, that is to say with a positive overlap, a negative overlap or an overlap of "zero".

As already stated, the disk surface may be convex-spherical. However, it is also possible to make the disk surface concave-spherical. The choice of this embodiment also depends on how the final disc geometry or overlap should be designed.

A further embodiment of the invention provides that the at least one disc surface has a radius or radius of curvature. This also allows the desired wheel geometry set. For example, can be adjusted by the crowning degree of overlap of the discs. Here then the crowning is to be chosen so that the discs have the desired overlap in the positive range, in the negative range or an overlap of "zero".

According to a further advantageous embodiment of the invention, a shoulder is provided on the outer diameter of the stator disks. This paragraph is to ensure that the discs can be arranged regardless of their thickness at the outer diameter between spacers in the vacuum pump.

A further advantageous embodiment of the invention provides that on the outer diameter of the stator disks, a disk portion has a smaller or larger thickness than the convex-spherical or concave-spherical disk portion. This also makes it possible to make the blades optically tight only at the inner diameter, but at the outer diameter optically permeable or vice versa.

According to a further advantageous embodiment of the invention, the thickness of the rotor or stator disc is formed in the blank decreasing from the inside to the outside. According to another embodiment of the invention, the thickness of the rotor or stator disk in the blank is increasingly formed from the inside to the outside. If it is increasingly formed from the inside to the outside, results without consideration of the blade angle to the outside an open structure with axial optical tightness.

In addition to the thickness of the blank inside, that is in the vicinity of the shaft, and the outside, that is in the direction of the spacers, also the radius, for example, the convex or concave crown is a factor that affects the overlap of the blades.

According to a further advantageous embodiment of the invention, the blank is processed by means of the high-speed cuttings. In high-speed cutting, the material is removed, that is, the channels are formed in the blank without exerting pressure on the blank. This has the advantage that the stability of the finished stator or rotor blade is not reduced.

The rotor or stator disc according to the invention for a vacuum pump, wherein the rotor or stator is made of a blank of solid material by sawing inclined to a disc plane channels, characterized in that at least one disc surface of the blank before the sawing of the channels radially symmetrical is formed curved.

As a result of this design of the rotor or stator disk, the overlapping of the blades can be optimized independently of the blade angle. The overlap can be both positive, it can be "zero", but it can also be negative.

According to a further advantageous embodiment of the invention, both disc surfaces are formed radially symmetrically curved. This means that viewed in the axial direction of the disc, both sides of the disc are curved. The disc surfaces may have a mirror-symmetric curvature. However, it is also possible to form the curvature of the two disc surfaces differently. For example, one side may be convex-crowned and the other side concave-spherical.

According to a further advantageous embodiment of the invention, the at least one disc surface is convex-spherical or concave-spherical. By this embodiment, the overlap of the blades can be selected, depending on the requirements of the finished disc.

According to a further advantageous embodiment of the invention, the at least one disk surface has a curvature with a radius or a curvature with a plurality of radii. This also allows the degree of overlap to be selected and the pumpability to be optimized with respect to the requirements of the disc.

According to a particularly preferred embodiment of the invention, a shoulder is provided on the outer diameter of the stator disks. This paragraph ensures a thickness-independent recording of the stator between spacer rings of the pump.

According to a further embodiment of the invention, a disc section on the outer diameter of the stator discs on a smaller or greater thickness than the convex-spherical or concave-spherical disc portion. This also makes it possible, for example, to make the blades only optically dense on the outside, but optically permeable on the inside, or to make the blades optically leakproof only on the inside and optically permeable on the outside.

"Inside" means towards the inner diameter of the disc, "outside" means towards the outer diameter of the disc.

According to a possible embodiment of the invention, the thickness of the rotor or stator disc is formed in the blank decreasing from the inside to the outside. There is also the possibility that the thickness of the rotor or stator disk in the blank is increasingly formed from the inside to the outside. This results, for example, without consideration of the blade angle, an outwardly open structure with axial optical tightness.

According to a particularly preferred embodiment of the invention, the stator or rotor disc is designed as a machined by means of high-speed cuttings stator or rotor disc. In high-speed cutting, the material is removed pressure-free for the formation of the channels, so that the workpiece is not subjected to any stresses or the like, and thus the finished stator or rotor disk has a particularly high stability.

According to a preferred embodiment of the invention, the stator or rotor disc after the sawing of the channels has an index between 0 and -0.20. In this case, the disc is visually dense. These discs have a very good compression.

According to a further advantageous embodiment of the invention, the disc is completely optically dense. This also gives the disc a very good compression ratio.

According to a further advantageous embodiment, the disc is formed on the outer diameter or the inner diameter optically sealed. Depending on the type of application, this also results in a very good pumping speed.

If the rotor disks have a larger thickness at the outer diameter than at the inner diameter and the thickness of the outer diameter deviates greatly from the thickness of the inner diameter, this can lead to strength problems due to high centrifugal forces due to the large mass accumulation at the outer diameter. If the stator disks have the spherical form described and if the rotor disk is correspondingly concave, then the rotor disk has an optically open structure open to the outside. However, as the rotor blades become thinner and thus lighter towards the outside, the centrifugal forces at the same speed are reduced to the rotor disk. Alternatively, the rotor disk can rotate faster without loading the disk material beyond the original dimension. This increases compression and suction, so that any reductions in these values due to the open rotor disk structure are compensated or even reduced.

Further features and advantages of the invention will become apparent from the accompanying drawings, in which several embodiments of a stator or rotor disk are shown only by way of example. In the drawing show:

1a a plan view of a disc blank according to the invention;

1b a section according to the line II of 1a ;

2a a plan view of a stator disc;

2 B a section according to the line II-II of 2a ;

3 a modified embodiment;

4 a rotor disk in plan view;

5 a section along the line AA the 4 ;

6 a rotor disk in side view;

7 a rotor disk in plan view;

8th a section after the line BB the 7 ;

9 a section after the line CC the 7 ;

10 a section along the line DD the 7 ;

11 a representation for the derivation to determine the openness of turbo geometries;

12a a plan view of a modified embodiment of a stator disc;

12b a section along the line XII-XII of 12a ,

1a and 1b show a blank 11 for a stator disc 1 which is convex-crowned. The larger pane thickness is on the outside diameter 3 arranged. At the inside diameter 2 points the blank 11 a thickness h1. At the outside diameter 3 points the blank 11 a thickness h2.

The blank 11 has a convex-spherical shape. Before introducing the channels for the stator or rotor blades, the blank becomes 11 formed in the final convex-spherical shape. That is, the blank 11 Prior to introducing the channels for the stator or rotor blades, the outer contour, which has the ready-made stator or rotor disk.

The blank 11 is formed from a convex-crowned blank, which is formed before introducing the channels for the stator or rotor blades in the final convex-spherical shape. That is, the blank 11 Prior to introducing the channels for the stator or rotor blades, the outer contour, which has the ready-made stator or rotor disk.

Depending on the design of the thickness h1 and h2 and the radius R of the convex crown, the overlap of the blades can be optimized independently of the blade angle. The overlap can be both positive, it can be "zero" (seen in the axial direction, the discs are just as optically dense), but it can also be negative (defined gap between the blades when viewed axially).

d1 determines the diameter of the inner diameter of the disc. Up to a diameter d2, the disc is plane-parallel. Between the diameters d2 and d3, the disc faces 1 a radially symmetric curvature of radius R on. Between the diameter d3 and d4, the disc is in turn formed plane-parallel, for example, between spacers of a turbomolecular pump (not shown) to be recorded.

This results in an open structure with axial optical tightness even without consideration of the blade angle on the outside.

It is possible, by choosing thickness and radius, to make the blades optically leakproof only on the outside, but visually permeable on the inside. It is also possible to make the blades only visually tight inside, but optically transparent outside.

1a shows the disc blank 11 , The disc blank 11 has a hole in the middle to accommodate the sawing.

2a and 2 B show a plan view of a disc 1 with the inside diameter 2 and the outside diameter 3 and the blades 4 , The stator disc 1 is completely optically tight executed in the axial direction. That is, looking in the plane of the drawing 2a The blades overlap into each other 4 to the outside diameter 3 ,

3 shows a partial section through a stator disc 5 , The stator disc 5 again has a convex-spherical cross section with the radius R. At the outer diameter 3 the stator disc 5 is a paragraph arranged. The heel is plane-parallel to the stator disc 5 between spacers (not shown) of the vacuum pump (also not shown) to order. Advantageously, in a vacuum pump, the stator discs according to the formation of the stator 5 shaped with the described spherical shape. The rotor disk can be correspondingly concave, so that the rotor disk has an optically open structure to the outside. As the rotor blades become thinner to the outside and thus lighter, the centrifugal forces are reduced to the rotor disk at the same speed. Alternatively, the rotor disk can rotate faster without loading the disk material beyond its original dimensions. This increases compression and suction, so that any reductions in these values due to the open rotor disk structure are compensated or even reduced.

Even in the formation of a concave-spherical shape of the blank is produced in its complete form concave-spherical. After this production, only the channels for the formation of the stator or rotor disks are introduced.

4 shows a rotor disk 7 with shovels 8th , In the area of the outside diameter 3 is no overlap of the blades 8th intended. The shovels 8th are not optically dense here. In the direction of the inside diameter 2 overlap the blades 8th and the rotor disk is optically tight.

5 shows a cross section of the rotor disk 7 , In 5 it can be seen that the rotor disk 7 has a convex-spherical shape. This shape is at the blank for the rotor disk 7 been given before the channels 9 ( 4 ) were introduced.

6 shows the rotor disk 7 , Again, you can see the convex-spherical shape of the rotor disk 7 ,

7 shows another rotor disk 10 with shovels 4 , The shovels 4 are arranged in the region of the outer diameter optically permeable to each other while in the direction of the inner diameter 2 are optically dense.

The 8th . 9 and 10 show sections along the lines BB, CC, DD the 7 , It is in each case the convex-spherical shape of the stator disc 10 to recognize.

11 shows two stator or rotor blades 4 having an opening angle α. The length of the blades is denoted by b, the height of the blades by h.

The width of the blades is the length SD.

The openness of the blades is determined as follows:

The openness is defined as the ratio of the area / distance not at least simply covered by the active rotor structure (the axially "transparent" portion) to the total distance / area swept by the active rotor structure. As soon as the value becomes negative, parts of the track / surface are covered not only simply but even twice by two adjacent rotor blades.

Optical tightness always exists when the openness on all possible diameters is less than or equal to zero. In this case, however, the parts and manufacturing tolerances are taken into account, so that can be spoken of a safely manufacturable, optical tightness only at a value slightly smaller than "zero".

The invention is characterized in that the stator disc 5 or the rotor disks 7 . 10 is turned as a completely closed disc. Subsequently, if the spherical shape, for example, the convex-spherical or concave-spherical shape of the stator 5 or the rotor disks 7 . 10 is worked out, the channels become 9 by sawing, for example, high-speed cutting in the discs 5 . 7 . 10 brought in.

12a and 12b show a stator disk 5 with shovels 4 , The shovels 4 do not overlap at the outside diameter. At the inside diameter 2 overlap the blades slightly.

The disc 5 according to the 12a and 12b is optically permeable.

LIST OF REFERENCE NUMBERS

1

stator

2

Inner diameter

3

outer diameter

4

shovel

5

stator

6

paragraph

7

rotor disc

8th

shovel

9

channels

10

rotor disc

11

blank

12

disk surface

13

disk surface

h1

thickness

h2

thickness

R

radius

d1

diameter

d2

diameter

d3

diameter

d4

diameter

b

scoop Long

H

blade height

S

blade spacing

SD

shovel width

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 10052637 [0003]
• DE 29715035 U1 [0004]

Claims (21)

Method for producing a rotor or stator disk for a vacuum pump, wherein the rotor or stator disk is produced from a blank made of solid material by sawing channels which are inclined to a disk plane, characterized in that at least one disk surface of the blank ( 11 ) before sawing the channels ( 9 ) is formed radially symmetrically curved. Method according to claim 1, characterized in that both disc surfaces ( 12 . 13 ) are formed radially symmetrically curved. Method according to claim 1 or 2, characterized in that the at least one disk surface ( 12 . 13 ) is formed convex-spherical or concave-spherical. Method according to one of the preceding claims, characterized in that the at least one disc surface ( 12 . 13 ) has a radius or radius of curvature. Method according to one of the preceding claims, characterized in that at the outer diameter ( 3 ) of the stator disks a paragraph ( 6 ) is provided. Method according to one of the preceding claims, characterized in that at the outer diameter ( 3 ) of the stator disc ( 1 . 5 ) has a disc portion has a smaller or greater thickness than the convex-spherical or concave-spherical disc portion. Method according to one of the preceding claims, characterized in that the thickness of the rotor or stator disc is formed in the blank decreasing from the inside to the outside. Method according to one of claims 1 to 6, characterized in that the thickness of the rotor ( 7 . 10 ) or stator disc ( 1 . 5 ) is increasingly formed in the blank from the inside out. Method according to one of the preceding claims, characterized in that the blank ( 11 ) is processed by means of high-speed cuttings. Rotor or stator disk for a vacuum pump, wherein the rotor or stator disk is made of a blank of solid material by sawing inclined to a disk plane channels, characterized in that at least one disk surface ( 12 . 13 ) of the blank ( 11 ) before sawing the channels ( 9 ) is formed radially symmetrically curved. Rotor or stator disc for a vacuum pump according to claim 10, characterized in that both disc surfaces ( 12 . 13 ) are formed radially symmetrically curved. Rotor or stator disc for a vacuum pump according to claim 10 or 11, characterized in that the at least one disc surface ( 12 . 13 ) is formed convex-spherical or concave-spherical. Rotor or stator disc for a vacuum pump according to one of claims 9 to 12, that the at least one disc surface ( 12 . 13 ) has a radius of curvature (R) or a radius of curvature. Rotor or stator disk for a vacuum pump according to one of claims 9 to 13, that at the outer diameter ( 3 ) of the stator discs ( 1 . 5 ) a paragraph ( 6 ) is provided. Rotor or stator disc for a vacuum pump according to one of claims 9 to 14, that at the outer diameter ( 3 ) of the stator discs ( 5 ) has a disc portion has a smaller or larger thickness than the convex-spherical or concave-spherical disc portion. Rotor or stator disc for a vacuum pump according to one of claims 9 to 15, that the thickness of the rotor or stator disc is formed in the blank decreasing from the inside to the outside. Rotor or stator disc for a vacuum pump according to one of claims 9 to 15, that the thickness of the rotor ( 7 . 10 ) or stator disc ( 1 . 5 ) in the blank ( 11 ) is increasingly formed from the inside out. Rotor or stator disk for a vacuum pump according to one of claims 9 to 17, that the stator or rotor disk ( 1 . 5 . 7 . 10 ) as a high-speed cuttings machined stator or rotor disk ( 1 . 5 . 7 . 10 ) is trained. Rotor or stator disk for a vacuum pump according to one of claims 9 to 18, characterized in that the rotor ( 7 . 10 ) or stator disc ( 1 . 5 ) has a coefficient of between 0.00 and -0.20 after sawing the channels. Rotor or stator disc for a vacuum pump according to one of claims 9 to 19, characterized in that the disc ( 1 . 5 . 7 . 10 ) is completely optically dense. Rotor or stator disc for a vacuum pump according to one of claims 9 to 20, characterized in that the disc ( 1 . 5 . 7 . 10 ) on the outer diameter ( 3 ) or in the direction of the inner diameter ( 2 ) is optically dense.

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