JPS649475B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a manufacturing method for manufacturing annularly arranged blades of a rotor of a turbomolecular pump, comprising:
A type of rotor in which the desired blade is formed by providing radial slits in the edge area of the blade disk and twisting the section left between the slits about the central radial axis of the section. Regarding.

The method for manufacturing annular vanes of the above type is known, for example, from Vakuumtechnik, Vol. 23, No. 4, page 109 and following pages. In this case, on the one hand, the blades should be as thin as possible so that they can be easily twisted and the end faces of the blades can be made as small as possible. That is, when considering the blade itself, the end surface of the blade has an "incident angle" perpendicular to the blade surface of the blade. Therefore,
All molecules that strike the end face of the vane are subjected to an impact force in the direction opposite to the desired transport direction provided by the vane face itself. The unfavorable effect of an opposite impact force being applied to the molecule by the end face is
The thicker the feathers, the larger they become.

On the other hand, the blades manufactured using the above type of manufacturing method are
It must not be too thin so that it has sufficient strength even at the high rotational speeds that occur. In blades produced by sawing and subsequent twisting, the width and thus the mass increases radially outwards, which results in additional demands on the strength. Furthermore, the vane disks used to make the vanes must not be too thin. This is because vane discs that are too thin will cause vibrations, for example when machining from one side, and the vibrations will interfere with accurate machining.

In all known turbomolecular pumps of the type mentioned at the outset, a compromise has been made with respect to the aforementioned mutually contradictory requirements regarding the blade thickness, which significantly defines the pumping properties of the turbomolecular pump.

In another type of production of turbomolecular pumps, the vanes are produced by making oblique slits in the edge area of the vane disc (for example, as described in Swiss patent no.
532199, see). Although such a manufacturing method avoids the end faces of the angle of incidence which give rise to disadvantageous effects, it is significantly more expensive than the manufacturing method of the type mentioned at the outset, which is the object of the invention.

It is therefore an object of the present invention to improve the manufacturing method of the rotor of a turbomolecular pump in such a way that a turbomolecular pump based on a manufacturing method of the type mentioned at the outset has significantly better pumping properties than conventional turbomolecular pumps. be.

In order to solve the above problems, the configuration of the present invention includes:
The blade disks used for manufacturing the annularly arranged blades are processed in such a way that the thickness of the blade disks decreases continuously or stepwise radially outward; The slits were made by sawing in the radial direction.

A rotor constructed according to the above manufacturing method of the present invention can be operated at a significantly high rotational speed, that is, a significantly high circumferential speed. This is because the thickness of the blades decreases radially outwards, and thus the mass of the blades likewise decreases radially outwards. As a result, the suction capacity of the turbomolecular pump is significantly increased and the degree of compression is also increased, especially when compressing light gases such as, for example, H ₂ . In the outer edge region where the circumferential speed of the vane is particularly high, the thickness of the vane and thus the detrimental end faces are reduced, resulting in good pumping properties.

Preferably, the thickness in the hub region of the blade is greater than the thickness in the edge region by a factor of 5 to 15. If the diameter of the blade disc is approximately 18 cm, it is advantageous if the blade thickness is reduced from approximately 5 mm to approximately 0.5 mm.

Generally, in the rotor of a turbomolecular pump,
A plurality of annular blade disks are arranged one on top of the other, and the length and/or incidence angle of the annular blade in each blade disk decreases from the high vacuum side to the low vacuum side. In many cases, the blade discs are partially different. Therefore, the blades are fabricated on individual blade disks that are unrelated to each other, and the blade disks from which the blades have been fabricated are assembled into a rotor in a predetermined order. However, it is particularly advantageous if the rotor is formed from a one-piece component. For this purpose, a cylindrical block made of aluminum, for example, is first provided with a recess perpendicular to the axis, again in such a way that ribs as vane discs of the annular vanes remain between the recesses. At the same time during the manufacturing step in which the cutouts are formed, for example by turning, the ribs remaining between the cutouts are reduced in thickness radially outwards. The blades are then formed by sawing and twisting in a manner known per se.

Next, embodiments of the present invention will be specifically described using the drawings.

The vane disk 1 shown in FIG. 1 has a thickness that decreases continuously in the edge region 2. The blade disk 1 shown in FIG. The thickness of the boss 3 with the axis 4 is chosen in such a way that a rotor for a turbomolecular pump can be constructed by superimposing the vane disks 1 and fixing them to each other.

In the blade disk 1 shown in FIG.
6 and 7, the radially outward direction is reduced.

FIG. 3 shows a plan view of a part of the vane disk 1. As shown in FIG. Also shown in FIG. 3 are some radial slits 9 formed by sawing. The sections 10 left between the slits 9 are twisted about the radial central axis of the sections 10 to form the desired vane. Advantageously, the vanes have different lengths, angles of incidence or widths, depending on the position of the vane disk relative to the high vacuum side. The length and width of the blades are determined by the length or depth and spacing of the slits 9. Different angles of incidence are defined by varying the amount of twist in the blade twist. In particular, it is desirable to make the mutual spacing of the blades as large as possible on the high vacuum side of the rotor. An increase in the mutual spacing of the vanes is possible by widening this width for forming the slits 9.

FIG. 4 shows an as yet unfinished rotor 11 manufactured from one-piece component. In order to manufacture the rotor from a one-piece component, a radial cutout 12 is made in the cylindrical aluminum block.
are provided, and these cutouts have a width and depth such that the blades are formed from the portions 13 left between the cutouts. For this purpose, the portions 13 remaining between the notches 12 are reduced in thickness radially outwards, either directly when forming the notches 12 by turning or later in a special machining step using a turning tool. Direction rate is reduced. In the embodiment of FIG. 4, the portions 13 between the cutouts 12 are reduced in stages. The outer region of the part 13 is then sawed out and twisted in the manner already shown in FIGS. 2 and 3, so that the integral rotor 11 is formed.

A rotor manufactured according to the invention for a turbomolecular pump can be operated at up to 40% higher rotational speeds than rotors according to the prior art, ie with blades of constant thickness. For example, if an aluminum rotor is designed in the prior art for a speed of 42,000 revolutions per minute, if the aluminum rotor is manufactured according to the invention, the aluminum rotor according to the invention can be operated at approximately 59,000 revolutions per minute. . The compression values are therefore significantly increased and the suction capacity, especially for light gases, is increased.

[Brief explanation of drawings]

The drawings show a plurality of embodiments of the present invention, in which FIG. 1 is a cross-sectional view of the blade disk of the first embodiment, FIG. 2 is a cross-sectional view of the blade disk of the second embodiment, and FIG. The figure is a plan view of a part of the blade disk of the embodiment shown in FIG.
The figure is a longitudinal sectional view of a rotor according to a third embodiment. DESCRIPTION OF SYMBOLS 1... Vane disk, 2... Edge range, 3... Boss, 4... Axis line, 5, 6, 7... Step part, 9... Slit, 10... Division, 11... Rotor, 12... Notch, 13... Part.

Claims (1)

[Claims] 1. A manufacturing method for manufacturing annularly arranged vanes of a rotor of a turbomolecular pump, which comprises providing radial slits in the edge area of the vane disc and leaving a gap between the slits. In those types in which the desired blade is formed by twisting the sections about the central radial axis of the section, the blade disks 1, 13 used for making the annular blade are A rotor of a turbo-molecular pump characterized in that the blade diameter is machined so that the blade diameter decreases continuously or stepwise toward the outside in the radial direction, and then the blade disk is sawed in the radial direction to form slits. Manufacturing method. 2. A method for manufacturing a rotor for a turbo-molecular pump according to claim 1, wherein the blade disks 1 are individually processed and assembled into one rotor. 3. The method for manufacturing a rotor for a turbo-molecular pump according to claim 1, wherein a plurality of blade disks used for manufacturing the annular blades are cut out from an integral component by turning. 4. A rotor for a turbo-molecular pump, characterized in that the thickness of the annularly arranged blades of the rotor decreases radially outward in a continuous or stepwise manner. 5. The rotor of a turbomolecular pump according to claim 4, wherein the thickness of the boss region of the vane is greater by a factor of 5 to 15 than the thickness of the edge region. 6. The rotor of a turbomolecular pump according to claim 4, wherein the rotor is formed from an integral component. 7. The rotor of a turbo-molecular pump according to claim 4, wherein the interval, width, length, and angle of incidence of the annular vanes of each vane disc are different from each other among the vane discs.