U.S. patent application number 12/781100 was filed with the patent office on 2010-11-18 for method for surface strengthening and smoothening of metallic components.
This patent application is currently assigned to ROLLS-ROYCE DEUTSCHLAND LTD & CO KG. Invention is credited to Goetz G. FELDMANN, Thomas HAUBOLD, Wolfgang HENNIG, Oleksandr KYRYLOV.
Application Number | 20100287772 12/781100 |
Document ID | / |
Family ID | 42610071 |
Filed Date | 2010-11-18 |
United States Patent
Application |
20100287772 |
Kind Code |
A1 |
HENNIG; Wolfgang ; et
al. |
November 18, 2010 |
METHOD FOR SURFACE STRENGTHENING AND SMOOTHENING OF METALLIC
COMPONENTS
Abstract
With a method for surface strengthening and smoothening of
metallic components, in particular of rotors or rotor drums (7)
with integral blading for aircraft engines, the components are
loaded in a vessel (2) which is filled with strengthening elements
(10). A tumbling movement is performed by which the metallic
components are strengthened and smoothened by a relative movement
between the workpiece surface and the strengthening elements in one
process step. The strengthening elements (10) have a
circumferential, rounded edge area, or compressive strengthening
area (13) for strengthening the surface, and, extending therefrom
on both sides, a flatly curved smoothening area (14) for
smoothening the surface roughened by strengthening. With low time
and apparatus investment, workpieces can be provided that feature
high fatigue strength and advantageous aerodynamic properties.
Inventors: |
HENNIG; Wolfgang; (Simmern,
DE) ; HAUBOLD; Thomas; (Wehrheim, DE) ;
KYRYLOV; Oleksandr; (Frankfurt/Main, DE) ; FELDMANN;
Goetz G.; (Oberursel, DE) |
Correspondence
Address: |
SHUTTLEWORTH & INGERSOLL, P.L.C.
115 3RD STREET SE, SUITE 500, P.O. BOX 2107
CEDAR RAPIDS
IA
52406
US
|
Assignee: |
ROLLS-ROYCE DEUTSCHLAND LTD &
CO KG
Blankenfelde-Mahlow
DE
|
Family ID: |
42610071 |
Appl. No.: |
12/781100 |
Filed: |
May 17, 2010 |
Current U.S.
Class: |
29/889 ;
72/362 |
Current CPC
Class: |
Y10T 29/49316 20150115;
B24B 31/14 20130101; F05D 2230/90 20130101; B24B 39/006 20130101;
B24B 31/06 20130101; Y02T 50/673 20130101; F01D 5/34 20130101; Y02T
50/60 20130101 |
Class at
Publication: |
29/889 ;
72/362 |
International
Class: |
B21D 53/78 20060101
B21D053/78; B21D 31/00 20060101 B21D031/00 |
Foreign Application Data
Date |
Code |
Application Number |
May 15, 2009 |
DE |
10 2009 021 582.4 |
Claims
1. A method for surface strengthening and smoothening a metallic
component, comprising: providing strengthening elements having
circumferentially rounded compressive strengthening areas for
strengthening a surface of the metallic component, and, extending
therefrom on both sides, flatly curved smoothening areas for
smoothening the surface roughened by strengthening; and placing the
metallic component and a plurality of the strengthening elements in
a vessel, and creating a relative movement between the surface of
the metallic component and the strengthening elements to
simultaneously strengthen and smooth the surface of the metallic
component.
2. The method of claim 1, and further comprising: causing the
strengthening elements to circulate horizontally and vertically
within the vessel, as well as to have vibratory movement; adjusting
a mass of each strengthening element to these movements; and
causing the strengthening elements to access confined areas of the
metallic component via a flattened shape of the strengthening
elements.
3. The method of claim 2, and further comprising masking surface
areas of the metallic component which are not to be
strengthened.
4. The method of claim 3, and further comprising providing the
compressive strengthening areas in at least one of a circular and
an elliptical form.
5. The method of claim 4, and further comprising providing the
compressive strengthening area of each strengthening element with
cross-sectionally circle segment form having a small radius, and
providing the smoothening areas in spherical segment form having a
several times larger radius then the compressive strengthening
area.
6. The method of claim 1, and further comprising providing the
strengthening elements as spheres, each with a formed-on,
circumferential ring, with a rounded free edge of the ring forming
the compressive strengthening area and the two free spherical
surfaces forming the smoothening area.
7. The method of claim 1, and further comprising providing the
strengthening elements as flattened spheres whose circumferential
small-radius edge area forms the compressive strengthening area and
whose opposite large-radius areas form the smoothening areas.
8. The method of claim 7, and further comprising providing the
strengthening elements in lenticular form.
9. The method of claim 7, and further comprising providing the
strengthening elements in disk-shaped form.
10. The method of claim 4, and further comprising providing the
strengthening elements in stainless steel.
11. The method of claim 1, wherein the metallic component is at
least one of an aircraft engine rotor and an aircraft engine rotor
drum.
Description
[0001] This application claims priority to German Patent
Application
[0002] DE102009021582.4 filed May 15, 2009, the entirety of which
is incorporated by reference herein.
[0003] This invention relates to a method for surface strengthening
and smoothening of metallic components, in particular of rotors or
rotor drums with integral blading for aircraft engines, and to a
strengthening element conceived for the performance of the
method.
[0004] The rotors of gas turbines, in particular aircraft engines,
are subject to high operational stress especially in the bladed
area. In order to reduce the wear resulting therefrom and increase
fatigue strength, it is known to strengthen the surface of the
rotors in the bladed area by shot peening. In this process, steel
or ceramic peening shot accelerated by compressed air is propelled
with high speed via nozzles onto the surface sections to be
strengthened which, in particular in the bladed area, are subject
to high wear. Other known methods for surface strengthening are
ultrasonic peening, laser-shock peening or roller burnishing.
[0005] In order to reduce the high apparatus and time investment
incurred with sectional surface strengthening by shot peening, it
is proposed in Specification EP 1731262 A1 to load the component to
be surface-strengthened into a vessel which is filled with
spherical shot and performs a tumbling movement. The tumbling
movement produces a relative movement between the workpiece moving
together with the vessel and the spherical shot, as a result of
which the shot impacts the workpiece surface thereby effecting
strengthening of the latter.
[0006] Besides surface strength, minimum roughness of the surface
of the rotors of aircraft engines is a further important
requirement for good aerodynamic properties and maximum efficiency
of the engine. However, shot peening incurs a significantly
increased surface roughness which fails to satisfy the requirements
on the efficiency of the engine and demands a subsequent
surface-smoothening grinding and polishing treatment incurring
considerable work and equipment investment.
[0007] In a broad aspect, the present invention provides a method
for surface strengthening and smoothening of metallic components,
in particular of rotors with integral blading for aircraft engines,
which keeps apparatus and time investment low and effects both
strengthening and smoothening of the workpiece surface, which
otherwise, while being strengthened, would also be roughened by the
impacting shot.
[0008] In the process of surface strengthening and smoothening of
metallic components, in particular of rotors or rotor drums with
integral blading for aircraft engines, the components, which are
loaded in a vessel filled with strengthening elements and
performing a tumbling movement, are strengthened by vertically and
horizontally circulating as well as vibrating movements of the
strengthening elements and, in the same operation, the strengthened
surface is also smoothened.
[0009] Simultaneous strengthening and smoothening of the workpiece
surface is obtained by a specific shape of the strengthening
elements moved relative to the workpiece surface, these having a
circularly or elliptically circumferential, rounded edge area, or
compressive strengthening area for strengthening the surface, and,
extending therefrom on both sides, a flatly curved area for
smoothening the surface. The workpieces, for example, an
aircraft-engine rotor drum including several rotors with integral
blading, can thereby be strengthened and immediately smoothened in
one operation in one and the same apparatus with low time and
apparatus investment and will have high fatigue strength and
advantageous aerodynamic properties.
[0010] For producing the kinetic energy required for strengthening
and smoothening, the strengthening and smoothening elements have a
mass adjusted to the movement imparted onto them. Owing to their
flattened shape, the strengthening and smoothening elements,
despite the relatively large volume, will also access confined
workpiece areas. Surface areas of the workpiece which are not to be
strengthened are masked during the treatment.
[0011] The strengthening and smoothening elements provided for the
performance of the method have a circularly or elliptically
circumferential, rounded edge area or compressive strengthening
area, respectively, and, extending therefrom on both sides, a
flatly curved smoothening area.
[0012] The circumferential compressive strengthening area
cross-sectionally forms a circle segment with small radius, while
the smoothening area forms a spherical segment with many times
larger radius.
[0013] In an advantageous development of the present invention, the
strengthening and smoothening elements are provided as spheres with
formed-on, circumferential ring, with a rounded free edge of the
ring forming the compressive strengthening area and the two free
spherical surfaces the smoothening area.
[0014] In a further development of the present invention, the
strengthening and smoothening elements are provided as flattened
spheres whose circumferential small-radius edge area forms the
compressive strengthening area and the opposite large-radius areas
extending on both sides from the edges form the smoothening
areas.
[0015] In a further development of the present invention, the
strengthening elements are lenticular.
[0016] In a further development of the present invention, the
strengthening elements are disk-shaped.
[0017] In a further development of the present invention, the
strengthening elements are made of stainless steel.
[0018] The present invention is more fully described in light of
the accompanying drawing.
[0019] FIG. 1 shows an embodiment of an apparatus for compressive
strengthening and simultaneous smoothening of the surface roughened
by the peening pressure;
[0020] FIG. 2 shows an embodiment of a strengthening and
smoothening element for use in the present method, having an oval
cross-section all around;
[0021] FIG. 3 shows an alternative embodiment of the strengthening
and smoothening element, having a lenticular shape;
[0022] FIG. 4 shows an alternative embodiment of the strengthening
and smoothening element, having a raised circumferential ring;
[0023] FIG. 5 shows a further alternative embodiment of the
strengthening and smoothening element, having a raised
circumferential ring; and
[0024] FIG. 6 shows a further alternative embodiment of the
strengthening and smoothening element, having a raised
circumferential ring.
[0025] FIG. 1 shows, connected to an unbalanced motor drive 1, a
vessel 2 with a centrally arranged base 3 and, arranged thereon, a
mounting plate 4 for retaining the workpiece 5 to be processed. The
workpiece 5 is a rotor drum 7 including several rotors 6 weldedly
joined to each other and integrally bladed (blisks) of which the
surfaces exposed in operation to an air or hot-gas flow, in
particular the blade surfaces and the surfaces remaining between
the blades 8, are both to be strengthened by application of peening
pressure to obtain high fatigue strength and be provided with the
low surface roughness necessary to enhance the aerodynamic
properties and the efficiency of the turbomachine. The vessel 2,
which is provided with a protective lining 9, is filled with a
processing medium 11 made up of a multitude of strengthening and
smoothening elements 10 to a level beyond the rotor drum 7. For
clarity, the strengthening and smoothening elements 10 are shown
enlarged in the drawing. As shown in the drawing, those portions of
the workpiece 5, here the rotor drum 7, whose surface is to be
excluded from processing, or which are to be prevented from being
accessed by the strengthening and smoothening elements 10, can be
masked with masking elements 12.
[0026] An essential characteristic of the strengthening and
smoothening elements 10 in the vessel 2 is that they have
considerably larger mass than the spherical shot used in shot
peening and accelerated by compressed air. This large mass is
required for the production of the kinetic energy necessary for
peening pressure strengthening of the workpiece surface since only
the tumbling movement of the vessel 2 and the workpiece 5 is
available for effecting vibration and circular movement and,
compared to shot peening, low acceleration of the strengthening and
smoothening elements 10. This large mass is essentially achieved in
that the strengthening and smoothening elements 10 have an
essentially oval cross-sectional shape (see FIG. 2) or a lenticular
shape (see FIG. 3). Compressive strengthening is effected by
impingement of the edge areas, or the compressive strengthening
area 13, with correspondingly small radius (corresponding to a
sphere diameter of 0.8 mm, for example) of the strengthening and
smoothening elements 10, while the large-radius areas, or
smoothening areas 14, impinging on the thus strengthened, but
roughened surface of the workpiece 5 provide, in one and the same
process, for a surface smoothening of the surface roughened by
compressive shot strengthening. Upon strengthening and smoothening,
roughness values of less than 0.25 .mu.m [Ra] are, for example,
achievable which are favorable for aerodynamics and thus the
efficiency of the engine.
[0027] Accordingly, besides the relatively high mass, an important
characteristic of the strengthening and smoothening elements 10,
which simultaneously act as smoothening elements, is the provision
of approximately semicircular compressive strengthening areas 13
and, opposite these, nearly flat smoothening areas 14 with always
considerably larger radius. The strengthening and smoothening
elements 10 can, for example, be lenticular or disk-shaped (see
FIG. 3), or be satellite-like elements (see alternative embodiments
shown in FIGS. 4, 5 and 6) cross-sectionally re-created to the
shape of the planet Saturn. The flatly conceived cross-sectional
shape of the strengthening and smoothening elements 10, although
significantly larger in comparison with conventional peening shot,
enables them, despite their larger volume, to access even confined
spaces and therein effect compressive strengthening in conjunction
with smoothening of the workpiece surface. Variations on the shown
shapes also fall within the scope of the invention.
LIST OF REFERENCE NUMERALS
[0028] 1 Unbalance motor drive [0029] 2 Vessel [0030] 3 Base [0031]
4 Mounting plate [0032] 5 Workpiece [0033] 6 Rotor with integral
blading [0034] 7 Rotor drum [0035] 8 Blades [0036] 9 Protective
lining [0037] 10 Strengthening and smoothening elements [0038] 11
Processing medium [0039] 12 Masking element [0040] 13 Compressive
strengthening area, edge area [0041] 14 Smoothening area
* * * * *