Stator disc for a turbomolecular pump

Abstract

A stator disc for a turbomolecular pump has an inner ring (3), an outer ring (4), and a plurality of vanes (2) formed of a stator disc plane, extending between the inner and outer rings (3, 4), and having, in connection regions of the vanes with the inner and outer rings, respective radial webs (5) a circumferential width (S) of which is smaller than a vane width (T).

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a stator disc for a turbomolecular pump and having a plurality of vanes curved out of the disc plane and having their opposite ends connected with the outer and inner rings of the disc. [0003] 2. Description of the Prior Art [0004] In turbomolecular pumps rotor and stator discs are alternatively arranged, with the rotor discs being arranged on a rapidly rotatable shaft. The stator discs are fixedly secured in the pump housing. Both types of discs have vanes, and their cooperation, together with a rapid rotation, produces the pumping effect. It is known to produce the vanes of both types of discs by milling them out of solid discs. This process is time-consuming and expensive. That is why stamped stator discs are used. Such discs are disclosed, e.g., in German Laid-Open Application DE-0S 37 22 164. In the disclosed process, solid discs are stamped out of sheet metal. Then, radial slot...

AI Technical Summary

Benefits of technology

[0010] In comparison with the state of the art, the inventive stator disc has a smaller deformable material region which, moreover, requires a smaller degree of deformation. As a result, stresses in the component are reduced, which eliminates straightening costs. With the elimination of a need for straightening, a higher precision of the disc measurements can be achieved. Because of smaller deformation forces and fewer operational steps are required, cheaper tools can be used. The portion of the tool costs within overall manufacturing costs is reduced, which makes adaptation of the stator disc to the vacuum-technical requirements economical.

[0011] Because with the inventive stator disc, the disc dimensions can be retained better than in the state of the art, the use of the inventive stator disc in a turbomolecular pump results in reduction of the clearances within the pumps and, thereby, in improvement of the pumping action.

[0013] Arrangement of the web at a half distance between opposite edges of a vane provides for a uniform loading of the web. The web loading is caused by the different gas pressure above and beneath the stator disc. Because of a symmetrical arrangement, the torques which act on the web, have the same power but opposite signs. As a result, no resulting torque appears on the radial axis of the vane and the web. This reduces the loading of the material.

[0015] A further manufacturing advantage results from forming the stator disc of a plurality of identical disc sections. In this case, only a single form for the disc section is necessary. This also facilitates assembly as the disc sections cannot be mixed and / or improperly combined.

[0016] A further manufacturing advantage is achieved by forming the vanes in a single step, all at once, curving simultaneously all of the vanes of a disc out of the disc plane. This permits to significantly reduce the operational time.

Problems solved by technology

This process is time-consuming and expensive.

The drawback of the known state of the art technology consists in that in connection regions between the inner ring and the vanes or between the vanes and the outer ring, a large degree of deformation takes place.

In addition, the forces with which the necessary degree of deformation can be achieved, are very large.

This type of deformation leads to high stresses in the material which results in the distortion of the disc and the necessary process of straightening the disc.

This adversely affects the achievable precision of the disc shape.

A further drawback of the known process consists in that the process requires use of extravagant and, therefore, very expensive tools.

A flexible dimensioning of discs, which should be optimally adapted to the operative range of a pump, i.e., to vacuum-technical requirements, cannot be realized with justifiable costs at a small number of workpieces.

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