WO2012140103A1

WO2012140103A1 - Method for producing a single-piece rotor portion and single-piece rotor portion

Info

Publication number: WO2012140103A1
Application number: PCT/EP2012/056612
Authority: WO
Inventors: Goetz G. FELDMANN
Original assignee: Rolls-Royce Deutschland Ltd & Co Kg
Priority date: 2011-04-12
Filing date: 2012-04-12
Publication date: 2012-10-18
Also published as: EP2697014A1; US20130216391A1; DE102011007224A1

Abstract

The invention relates to a method for producing a single-piece rotor portion (9), especially of a jet engine (1). The rotor portion (9) comprises an annular base (10) and a plurality of blade elements (11) distributed over the periphery and extending away from the base (10) in a substantially radial fashion. Residual stress is introduced by deep rolling into near-surface portions of the blade elements (11) by means of deep rolling tools that engage between the blade elements. During deep rolling, a portion of a blade element (11) is arranged between portions of the deep-rolling tool and lateral sides of the blade element are deep-rolled at the same time. According to the invention, the deep-rolling tool is introduced radially between the blade elements (11) and the surfaces of the blade elements are deep-rolled, resulting in at least the blade elements (11) having deep-rolled surfaces.

Description

METHOD FOR PRODUCING A ONE-PIECE ROTOR AREA

AND ONE PIECE OF ROTOR

The invention relates to a method for producing a one-piece rotor region according to the preamble of claim 1 and an integral rotor portion according to the closer defined in the preamble of claim 9. Art.

Known from practice jet engines ei ^¬ nes blower are carried downstream with multistage compressors, is gradually performed in the region of which run in a core flow stream of air to a desired pressure level. The individual compressor stages are formed by rotor elements rotating in the operation of a jet engine or rotating blades of one-piece rotor regions and thus corresponding blade elements or stationary vanes.

In the region of the stationary stators act comparatively low mechanical loads in the operation of a jet engine, on the one hand not attack due to rotation centrifugal forces ^¬ and secondly blade vibrations are minimized by the residual stress of the flow profile of the foot and Kopfbe ^¬ kingdom.

In the field of rotating blades, however, high mechanical loads act in the operation of a jet engine. Their total load is made up of several part-loads, with centrifugal force being the dominant part-load. Due to the operation of a jet engine only small auftre ^¬ tender speed changes, the centrifugal force, which is superimposed by dynamic part loads, approximately considered statically. The dynamic part loads result from the rotational vibration excitation of the blades or the blade elements. Furthermore, aerodynamically induced loads on the rotor blades, which are mainly due to periodic transient currents, act on the rotor blades. Generally, transient flows occur through the stator-rotor interaction, which is created by the division of the flow by the passage of the blades past the vanes. Furthermore, dynamic loads are caused by the interaction of the flow profiles with the turbulent flow, which also results in blade vibrations. The sum of the dynamic part loads leads to the occurrence of high-frequency oscillations during operation, especially in the area of rotating blades of compressors and also of fans or in general of integral rotor sections of jet engines, which lead to highly dynamic loading of the rotor blades.

In addition to mechanical loads, a part of the blades is also subjected to thermal stress. This applies above all to the blades of the high-pressure compressor and the rear blades of the low-pressure compressor, where operating temperatures of up to 600 ° C are reached.

Generally, blades of compressors or blowers of jet engines are designed such that the dynamic operating loads do not exceed the fatigue strength or only defined and a fatigue strength and a defined level of fatigue resistance is ensured. However, there is always a premature crack initiation and sometimes even an uncontrolled failure of fan and compressor blades, which is mainly due to damage to the blades due to foreign bodies. Such foreign body damage is impact damage caused by the impact of hard foreign bodies. The foreign bodies are generally stones and fragments of screws, nuts, washers and the like, which are located on the runway and the runway.

If a foreign body hits, it often splinters. Most of these pieces Splitter also penetrate as objects that have passed through the fan area without collision, with the air flow ^¬ deeper into the engine one. If the engine has a large secondary airflow, some of the objects may leave the engine above it without causing further substantial damage. The other part comes with the core air flow into the low-pressure compressor and goes there momentous Kollisi ^¬ tions especially with the rapidly rotating blades one. Here is the Hauptschädigungsort due to the Kine ^¬ matics, similar to the wind, in the area of the leading edge and the front concave profile page.

In order to protect the vane elements or the blades to foreign body damage, and to avoid from these resulting in each case in operation crack formation in the region of the blades, the blade elements and integral therewith executed annular base body be designed appropriately massive ^¬ lead. The undesirably high use of material increases the overall weight and manufacturing costs of a jet engine, which is not desirable.

For this reason, it has begun to consolidate Laufschau ^¬ blades or blade elements of jet engines via suitable manufacturing processes in order to run the blades compared to not nachverfestigten blades with smaller component dimensions can. For this purpose, the rotor blades and thus integrally executed annular body of a rotor area with ^{¬ means} shot peening, wherein during the ball ^¬ jet process in the near-surface regions of the blades residual stresses are generated, which counteract a resulting from a foreign body damage or vibration stress cracking and its crack propagation to the desired extent ,

However, the disadvantage here is that the surfaces of rotor blades which have been subsequently solidified by means of shot peening have a low surface quality which, after the post-consolidation process, has to be improved again during costly and therefore costly reworking steps. The width ^¬ ren is a uniform machining of blades or blade elements of the one-piece rotor areas by means of shot peening rebounds and downs ^¬ shadowing can not be guaranteed for example due because surface areas häufi ^¬ ger be hit by ball elements than other surface areas, which in turn adversely affect the life ^¬ permanent effects, such as softening effects, and reproducible processing results are not guaranteed. A solidification of one-piece rotor areas by means of shot peening is therefore also very inaccurate and moreover expensive due to the use of compressed air.

Furthermore, it is known to roll blades by means of pliers tools in areas and to generate residual stresses in the blades in near-surface areas. In each case one of the flow facing blade ^¬ rich is solidified by a directed in the flow direction or in the axial direction engagement of a rolling tool by deep rolling. In this case, usually in about 20% of the surface of a blade element, starting from the Strö- mungseintrittskante of the blade element in the flow direction by simultaneous rolling on both sides of the longitudinal sides fest ^¬ rolled, whereby a high surface ^quality is achieved or maintained at ^¬ and also deformations thin-walled profiles are avoided.

However, this approach has the advantage that the present transition between nachverfestigten by means of deep rolling surface area of a blade element and the non nachver ^¬ solidified surface region of a blade element voltage jumps on Ü the disadvantage. During attack at the blade element ^¬ the resonant loads are exceeded in this transition region voltage upper limit, so that plastic flow in the region between the processed area of a blade element and the non-working by means of deep rolling Oberflä ^¬ chenbereich occur which can cause undesired cracking. Once cracks have occurred, they continue to vibrate and eventually lead to failure of a blade element.

The present invention is therefore based on the object to provide a method for producing a one-piece rotor section, preferably a jet engine, avail ^¬ supply, by means of which one-piece rotor sections with high resistance to foreign body damage and against vibration loads at the same time low component weight can be produced. In addition, the invention has for its object to provide a one-piece rotor area available, which is characterized by a high resistance to foreign body damage and vibration loads, is inexpensive to produce and whose surface is designed with a low roughness. According to the invention this object is achieved with a method having the features of claim 1 and with a einstü ^¬ ckigen rotor portion having the features of patent claim. 9

In the method according to the invention for producing a one-piece rotor region, preferably a jet drive ^{¬ which} comprises an annular base body and a plurality of circumferentially distributed blade elements which extend substantially radially from the base body, are in the blade elements via an intervening between blade elements rolling tool Deep rolling introduced in surface near ^¬ areas residual stresses. During the hard ^¬ rolling a portion of a blade element Zvi ^¬ rule areas of the rolling tool is arranged in each case and the longitudinal sides of the blade element to be deep rolled at the same time.

According to the invention the roller tool is radially inserted between the blade elements and the surfaces of the blade elements ^¬ be rolled.

Characterized in that the surfaces of the blade elements are rolled tightly ^¬ is a same consists of an annular body and a plurality of circumferentially spaced vane members formed integral rotor portion, preferably a jet engine ^¬ work, compared to non nachverfestigten rotor areas with less material and therefore smaller overall weight and or higher resistance to foreign body damage and vibration loads executable.

Furthermore, be avoided by rolling the surfaces of the blade elements voltage jumps and Be ^¬ permanence against vibration loads compared to only partially reinforced post-blade elements improved in a simple manner.

Since the rolling tool is introduced radially between the blade elements, there is a simple way also the possibility of integral rotor sections with a high resistance to ^¬ run against foreign body damage and vibration loads, which have a plurality of axially in succession arranged on the main body blade elements. This is not possible with methods known from practice, in which the rolling tool is introduced in the axial direction between the blade elements, due to the low Ab ^¬ states between the individual blade ^element rows.

In a marked by a small control and regulation cost variant of the method according to the invention, the surfaces of the blade elements are at least partially solid rolled by sequentiel ^¬ les radial retraction.

In an equally simple variant of the method according to the invention, the surfaces of the blade elements are rolled at least in regions by sequential axial traversing.

The surfaces of the blade members at least partially firmly rolled by belie ^¬ bige travel paths of the rolling tool along the surfaces of the blade members, the surfaces of the blade elements are providable with a time required for the generation of a homogeneous flow around the blade elements surface structure.

A resistance of a one-piece rotor region is in a further advantageous variant of the invention Increases the process by that transition areas between the surfaces of the blade elements and the surface of the body between the blade elements are rolled by means of a rolling tool.

A resistance to foreign body damage and vibration loads of a one-piece rotor area characterized by a low weight can be further improved if the surface of the base body is firmly rolled between the blade elements by means of a rolling tool.

To ver improve a durability of the blade members further ^¬, it is provided in a further advantageous variant of the inventive method is that a rolling force can be varied to optimal, the surfaces of the blade elements selectively with the ge ^¬ genüber respectively for increasing the resistance to foreign object damage and vibration loads near-surface compressive residual stress.

The one-piece rotor section according to the invention has an annular body and a plurality of distributed over the circumference of the body blade elements which extend radially We ^¬ sentlichen from the base body. Since at least the blade elements have a solidly rolled surface, the one-piece rotor region according to the invention is characterized by a lower weight compared to non-after-solidified rotor regions or only partially solidified one-piece rotor regions at least for the same resistance to foreign body damage and vibration loads and cost in the field of blade elements without additional manufacturing steps cost a surface characterized by a high surface quality. leads, which supports a homogeneous flow around the blade elements un ^¬ .

Also have connection areas between surfaces of the vane elements and an oil. ier surface of the body on a hard-rolled surface, both a resistance to foreign body damage and vibration loads and a homogeneous flow around the one-piece rotor area is guaranteed.

Resistance to foreign body damage and vibration loads is improved in a further advantageous embodiment of the integral rotor region according to the invention in that the base body has a solidly rolled surface at least in the region between the blade elements.

In a further advantageous embodiment disclosed embodiment of the integral rotor portion, a plurality of axially successively arranged on the base body blade elements pre ^¬ see, which are designed with a fixed rolled surface.

Both the features specified in the claims and the features specified in the following embodiment of the inventions ^¬ inventive article are each suitable alone or in any combination with each other to further develop the subject invention. The respective feature combinations represent no limitation with respect to the development of the subject matter according to the invention, but essentially have only an exemplary character.

Further advantages and advantageous embodiments of the subject invention result from the patent Spells and the embodiment described in principle below with reference to drawing.

It shows:

Figure 1 is a highly schematic longitudinal sectional view of a jet engine, which is designed with a einstü ^¬ ckigen rotor region.

2 is an enlarged detail view of a show ^¬ felelementes of the one-piece rotor portion of FIG. 1.

Fig. 3 is a side view of a rolling tool; and

Fig. 4, the rolling tool of FIG. 3 in a in

Fig. 3 marked in detail view IV.

Fig. 1 shows a longitudinal sectional view of a jet engine ^¬ plant 1, which is designed with a bypass duct 2. Furthermore, the jet engine 1 is formed with an inlet region 3, which is followed downstream by a fan 4 in a manner known per se. Again downstream of the fan 4, the fluid flow in the jet engine 1 is divided into a secondary flow and a core flow, wherein the secondary flow through the bypass channel 2 and the core flow into an engine core ^¬ 5 flows, in turn, in a ^conventional manner with a compressor device 6, a burner 7 and a turbine device 8 is executed.

In FIG. 2 is an enlarged detail view of a ^¬ lumpy rotor portion 9 of the compressor means 6 of an annular base body 10 and a plurality is shown on comprises the circumference distributed vane elements 11, which extend substantially radially from the base body 10.

The integral rotor section 9 constitutes a so-called blisk, which is an integrally bladed rotor construction. The term blisk is composed of the English words "blade" for shovel and "disk" for disc. The disc or the annular base body 10 and the sight ^¬ felelemente 11 are made of one piece, whereby provided at more ^¬ lumpy areas running rotor blade roots and disk grooves omitted. The one-piece rotor region 9 is characterized by a significantly smaller number of parts compared to conventionally bladed compressor rotors and the disk shape of the annular base body 10 is designed for a lower edge load. This results in that the Ge ^¬ weight of the one-piece rotor portion 9 is reduced in conjunction with the use of lightweight materials, by up to 50% compared to conventional rotor areas. The amount of Gewichtsre ^¬ duzierung in each case is dependent on the geometry of the compressor means. 6

Another positive effect is that the Schaufelele ^¬ elements 11 of the integrally bladed rotor portion 9 are arranged ge ^¬ ringerem distance from each other, whereby a maximum possible compression and the efficiency can be improved.

9 for For at the same time low weight ^¬ lead the compressor means 6 and the one-piece rotor portion to foreign body damage and vibration loads, are in the blade elements 11 shown in detail via a respective radially engages between the blade elements 11 and in Fig. 3 and Fig. 4 rolling tool 14 By hard ^¬ rolling in near-surface areas residual stresses eingell in each case, the entire surface of each blade element 11 is firmly rolled. In addition, transition regions 12 or fillets between the surfaces of the blade elements 11 and a surface 13 of the base body 10 between the blade elements 11 are also firmly rolled by means of a so-called single-finger rolling tool not shown in detail in the drawing.

Furthermore, the surface 13 or the annulus of the main body 10 between the blade elements 11 is preferably also firmly rolled by means of a single-finger rolling tool.

Each upper ^¬ surface near areas of the one-piece rotor portion 9 are solidified by increasing the dislocation density through the fixed rollers of the surfaces of the longitudinal sides and the edges of the blade members 11, the transition areas 12 and the surface 13 of the base body 10 and cured, the surface layer of the rotor region. 9 The hardening of the surface layer reduces the risk of cracks resulting from foreign body damage as well as vibration loads. In addition, the introduced into the material by the deep rolling compressive stresses result in the region of the rotor portion 9 to counteract that this a crack propagation ^¬ step after formation of a crack and thus have a positive effect as regards the fatigue strength and thus with respect to the life of the jet engine. 1

Furthermore, the one-piece rotor portion 9 through the deep rolling process, a high surface quality with a clotting ^¬ gen surface roughness, the 9 without the need for further subsequent to the solidification process process step to a positive effect on the aerodynamic quality of the blade members 11 and of the entire rotor area smoothing the surface has. FIGS. 3 and 4 each show a side view of a rolling tool 14 for deep rolling the longitudinal sides or the entire surface of the blade elements 11 of the rotor region 9. The rolling tool 14 comprises a tool carrier 15 which is connectable to a carrier spindle 16 of a machine tool in dar ^¬ stellenem extent. Two pliers body 17, 18 of the rolling tool 14 in the region of a pivot bearing 19 are rotatably connected to the tool carrier 15, wherein the pliers body 17, 18 are coupled via a presently acting as a single-acting piston-cylinder unit drive means 20 and a distance between Wälzbereichen 21, 22 is reduced as a function of a drive device-side rotational movement of the tong body 17 and 18 about the pivot bearing 19. For this purpose, the hydraulic pressure is applied to the drive device 20 and a piston element 23 moves out of a cylinder element 24 of the drive ^device 20 due to the applied hydraulic pressure, whereby a distance between the ends 25 facing away from the rolling regions 21 and 22 results from such a change in operating state of the drive device 20 and 26 the pliers body 17 and 18 is increased, while the distance between the Wälzbereichen 21 and 22 is reduced in accordance with the geometric conditions in dependence of the rotational movement of the pliers body 17 and 18 to the pivot bearing 19 around. The pliers body 17 and 18 are each rotatably connected to the drive device 20 in the region of their ends 25 and 26.

In addition, the two pliers body 17 and 18 around the pivot bearing 19 around an aligned with respect to the plane in the vertical direction of rotation axis 27 rotatably mounted on the tool carrier 15 to pivot when the Wälzbereiche 21 and 22 on a blade element 11, the pliers body 17 and 18 to be able to move through the system of rolling Rich 21 and 22 on the blade element conditional deformation of the blade elements 11 each to avoid. During the common ^¬ rotation of the tong body 17 and 18 to the pivot bearing 19 relative to the tool carrier 15, a distance between the Wälzbereichen 21 and 22 remains the same. Furthermore, it is also ensured by the joint rotatability of the two chuck bodies 17 and 18 about the rotary bearing 19 so that each blade profile having a blade elements 11 are festwalzbar about their ge ^¬ entire surface by the rolling die fourteenth

The pliers body 17 and 18 are connected via piston elements 28 and 29 with the tool carrier 15 in operative connection, wherein the pliers body 17 and 18 of the piston elements 28 and 29 relative to the tool carrier 15 about the pivot bearing 19 in a relation to the tool carrier 15 and in FIG. Defined zero position shown 3 are reset when a Zan ^¬ genkörper 17 and 18 together about the pivot bearing 19 twisting rotational force is substantially equal to zero.

Furthermore, the forceps bodies 17 and 18, a presently two spring means 30 and 31 comprehensive rear part ^¬ device 32 assigned, via a distance between the rolling areas 21 and 22 by reset device-side turning the tong body 17 and 18 in the direction of a maximum value is variable.

The Wälzbereiche 21 and 22 comprise present each a ball element 33, 34 which are respectively in support portions placed ^¬ accepted and can be acted upon in a known manner with hydrau ^¬ lischem pressure to the blade elements 11 with the required Wälzkraft via the ball members To act on 33 and 34. The holding portions 35 and 36 are present in the clamped bodies 17 and 18 fixedly connected via screw connections and at least approximately finger-like executed Adapterele ^¬ elements 37 and 38 and preferably screwed via set screws with them.

The adapter elements 37 and 38 are each interchangeable, whereby over the rolling tool 14 different ^{Eingriffstie ¬} fen in the radial direction between the blade elements 11 can be realized. In addition, designed adapter elements 37 and 38 are connected to the tong bodies 17 and 18 also in respect of the portable pressure or Wälzkraft, wherein thinner adapter elements are insertable into narrower areas between the cast ^¬ felelementen. 11 In this case, thinner blade elements 11 are acted upon by leaner adapter elements 37 and 38 with lower rolling or compression forces, since the adapter members 37 and 38 then have a certain elasticity ^¬ and the maximum Wälzkraft is limited by the elasticity of the adapter elements 37 and 38th A complete through ^¬ fixing of the blade members can be avoided during the deep rolling by limiting the maximum rolling force, since too high a compressive stress generates a Zugspannungsmaximum during the rolling process in the mitt ^¬ sized area of the blade members 11, which promotes ^¬ supply stress cracking from the inside out in oscillations. However, this is undesirable because of deterioration of a life of the vane elements 11.

The rolling force introduced during the deep rolling in the rotor area in each case via a not shown in the drawing pressure control unit to the desired extent at each point of a blade element 11 and also in the transition areas 12 and the remaining surface 13 of the body 10 by controlling the at the Wälzbereichen 21st , 22 variable hydraulic pressure to vary the rotor portion 9 to the desired extent by generating the necessary at each point of the rotor portion 9 optimum residual compressive stresses and to achieve an improvement in the durability of the blades.

For example, to simplify a deep rolling operation by means of the rolling tool 14 upstream CAD-CAM programming and a later implementation of the production programs by means of a post-processor to a multi-axis machining center, an axis 39 of the support spindle 16 is connected to the tool carrier 15 operating state between the Wälzbereichen 21 and 22nd by a contact point between the rolling areas 21 and 22 which is equal to zero at a distance between the rolling areas 21 and 22. Thus, the axis or the spindle support axis 29 and an axis through the contact point between the Wälzbereichen 21 and 22 congruent, whereby the programming of the rolling process is substantially simplified.

In order to avoid damage to the blade elements 11 to be machined and also of the rolling tool 14 itself, a distance between the rolling regions 21 and 22 can only be reduced by the drive device 20 to a defined limit value. The two ball elements 33 and 34 are by corresponding rotation or pivoting of the pliers body 17 and 18 and thus the adapter elements 37 and 38 are not brought into contact with each other, whereby damage to the rolling tool 14 are excluded in a simple manner.

By means of the rolling tool 14 are integrally bladed disks and rotors of jet engines at low cost festwalzbar. Due to the quick and easy replacement of the adapter elements 37 and 38, the rolling tool 14 is low Set-up times for different geometrically executed rotor areas can be used, wherein in addition to different depths of engagement between blade elements and different processing ^¬ forces during the rolling process on differently designed components with high security and process capability are darstell ^¬ bar.

By means of the pliers design of the rolling tool 14 is a treatment of blade elements or of Aerofoils of integral rotor sections from Tip to Fillet possible, with a simultaneous deep rolling of the pressure and suction sides of blade elements to avoid an inherent tension delay is provided.

In addition, by means of various individual tools, the processing of the fillets or the transition regions between the surface of the blade elements and the surface of the base body between the blade elements on the suction and on the pressure side to the desired extent feasible. Furthermore, the surface of the base body between the blade elements or the annulus by means of a single tool is festwalzbar.

In principle, the rolling tool 14 can be integrated into any known machining center. In contrast to a post-consolidation by means of shot peening, there are no expensive systems to procure. The Nachverfestigung Runaway can be, for example, in conventional milling by means of the rolling die 14 ^¬ leads. The milling centers are equipped with the rolling tool 14 and the surfaces of one-piece rotor sections are processed analogously to milling with the deep rolling tool 14 Be ^¬ rich their surface. Reference sign list

Jet engine

Bypass duct

intake area

blowers

Engine core

compressor means

burner

The turbine apparatus

one-piece rotor area annular base body

vane element

Transition area

Surface of the main body

rolling tool

tool carrier

Support spindle, 18 pliers body

pivot bearing

driving means

, 22 rolling areas

piston element

cylindrical member

End of the tong body 17

End of the tong body 18

axis of rotation

, 29 piston element

, 31 spring element

Rear sub-equipment

, 34 ball element

, 36 holding area

, 38 Adapter element

axis

Claims

claims

Method for producing a one-piece rotor region (9), preferably a rotor region (9) of a jet engine (1), wherein the rotor region (9) comprises an annular base body (10) and a plurality of circumferentially distributed blade elements (11) extending in the We ^¬ substantially from the base body (10) extend radially, wherein in the blade elements (11) via a respective intervening between the blade elements (11) rolling tool (14) by deep rolling in near-surface areas residual stresses are introduced, and wherein during the Festwal ^¬ zen each one area a blade element (11) is arranged between regions of the rolling tool (14) and longitudinal sides of the blade element (11) are simultaneously firmly rolled, characterized in that the rolling tool (14) extends radially between the blade elements

(11) and the surfaces of the blade elements

(11) are rolled.

A method according to claim 1, characterized in that the surfaces of the blade elements (11) are at least partially Festge ^¬ by sequen ^¬ tial radial Abfahren.

A method according to claim 1 or 2, characterized in that the surfaces of the blade elements (11) are solidly rolled at least in regions by se ^¬ quentielles axial Abfahren.

Method according to one of claims 1 to 3, characterized in that the surfaces of the blade elements (11) by any of routes of the rolling tool (14) along the surfaces of the blade elements (11) are at ^¬ least deep rolled in regions.

Method according to one of claims 1 to 4, characterized in that transition areas (12) between the surfaces of the blade elements (11) and the surface (13) of the base body (10) are firmly rolled between the blade elements (11) by means of a rolling tool.

Method according to one of claims 1 to 5, characterized in that the surface (13) of the base body (10) between the blade elements (11) by means of a rolling tool (14) is firmly rolled.

Method according to one of claims 1 to 6, characterized in that the surfaces of a plurality of axially successively arranged blade elements are firmly rolled.

Method according to one of claims 1 to 7, characterized in that a rolling force for adjusting an internal stress profile over the surfaces of the blade ^¬ elements and / or the transition regions and / or the surface of the body between the blade elements is variable.

9. One-piece rotor region (9) with an annular base body (10) and a plurality of circumferentially of the base body (10) distributed blade elements (11) which extend substantially from the base body (10) radially, characterized in that at least the blade elements ( 11) have a hard-rolled surface.

10. A one-piece rotor section according to claim 9, characterized in that transition regions between the upper ^¬ surfaces of the blade elements (11) and a surface (13) of the base body (10) between the blade elements (11) have a tightly rolled surface.

11. One-piece rotor portion according to claim 9 or 10, characterized in that the base body (10) at least in the region between the blade elements (11) has a solidly rolled surface (13).

12. One-piece rotor portion according to one of claims 9 to 11, characterized in that a plurality of axially Rich ^¬ tion behind one another on the base body arranged blade elements are provided, which are designed with a solid-rolled surface.