U.S. patent application number 12/724455 was filed with the patent office on 2010-10-28 for tooling for holding thin metal parts making up a hollow structure in order to enable them to be friction-welded together.
This patent application is currently assigned to EUROCOPTER. Invention is credited to Delphine ALLEHAUX, Philippe DURAND, Jean-Loup GATTI, Laurent MARCHIONE.
Application Number | 20100269326 12/724455 |
Document ID | / |
Family ID | 41328623 |
Filed Date | 2010-10-28 |
United States Patent
Application |
20100269326 |
Kind Code |
A1 |
ALLEHAUX; Delphine ; et
al. |
October 28, 2010 |
TOOLING FOR HOLDING THIN METAL PARTS MAKING UP A HOLLOW STRUCTURE
IN ORDER TO ENABLE THEM TO BE FRICTION-WELDED TOGETHER
Abstract
A tooling for holding parts in position to enable them to be
friction-welded together in order to construct a hollow structure,
the tooling includes: a framework made up of two frames for
receiving the parts for welding together in their positions for
forming the hollow structure, the parts including preformed parts
and an intermediate section; shape-holder members for holding the
hollow structure, associating backing thrust members and lateral
grip members for gripping the outsides of the preformed parts;
anvils suitable for being placed inside the set of preformed parts
beside the section; and clamping elements operable to take up a
clamping position in which they cause opposing thrust to be applied
against the anvil and the inside face of a preformed part, its part
itself bears against the shape-holder members.
Inventors: |
ALLEHAUX; Delphine; (Velaux,
FR) ; GATTI; Jean-Loup; (Marseille, FR) ;
MARCHIONE; Laurent; (Pourrieres, FR) ; DURAND;
Philippe; (Berre L'Etang, FR) |
Correspondence
Address: |
YOUNG & THOMPSON
209 Madison Street, Suite 500
Alexandria
VA
22314
US
|
Assignee: |
EUROCOPTER
Marignane Cedex
FR
|
Family ID: |
41328623 |
Appl. No.: |
12/724455 |
Filed: |
March 16, 2010 |
Current U.S.
Class: |
29/559 ;
269/43 |
Current CPC
Class: |
B64C 3/26 20130101; B64F
5/10 20170101; Y10T 29/50 20150115; B23K 20/126 20130101; B23K
37/0443 20130101; B23K 2101/045 20180801; Y10T 29/49998 20150115;
B23P 2700/01 20130101; B23K 37/0435 20130101 |
Class at
Publication: |
29/559 ;
269/43 |
International
Class: |
B25B 1/20 20060101
B25B001/20; B23Q 7/00 20060101 B23Q007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 27, 2009 |
FR |
09 02023 |
Claims
1. Holder tooling for holding parts (2, 3, 4) in order to enable
them to be friction-welded together to construct a generally plane
hollow structure (1), said hollow structure (1) being made up of a
set of preformed parts (2, 3) brought successively into abutment
against at least one internal stiffener section (4) that is
provided at the ends of its section with flanges (8, 9) for
receiving in overlap edges of the preformed parts (2, 3), the
tooling including at least one anvil (19, 20) suitable for
receiving the adjacent edges of the parts (2, 3, 4) for welding
together pressed thereagainst, and reversible clamping means (21,
22) suitable for causing said edges to be subjected to an opposing
thrust between the anvil (19, 20) and shape-holder members (25, 26)
of the hollow structure (1), wherein the tooling comprises: a
framework (31) for receiving the parts (2, 3, 4) for welding
together in their positions for forming the hollow structure (1),
the framework (31) being subdivided into two frames (12, 13)
provided with reversible junction means (17, 18) for joining them
together in an assembled position on either side of the hollow
structure (1) that is to be obtained, on either side of the general
plane in which it extends; said shape-holder members (25, 26, 27)
for holding the preformed parts (2, 3) installed inside the
framework (31), which members are carried by the framework (31); at
least one anvil (19, 20) suitable for being placed inside the set
of preformed parts (2, 3) installed inside the framework (31),
being placed laterally relative to the section (4), between its
flanges (8, 9); and said clamping means (21, 22) suitable for being
placed inside the set of preformed parts (2, 3) installed inside
the framework (31), which clamping means are movable into a
clamping position in which they cause opposing thrust to be applied
between the anvil (19, 20) and the inside face of at least one
preformed part (2, 3) associated with the clamping means.
2. Holder tooling according to claim 1, wherein the shape-holder
members comprise at least one lateral grip member (27) for gripping
an outer preformed part (2, 3) of the hollow structure (1) with
which it is associated.
3. Holder tooling according to claim 2, wherein the lateral grip
member (27) is mounted on the framework (31) via movement means
(28) enabling it to move between a disengaged position in which its
grip on the preformed parts (2, 3) associated therewith is capable
of being interrupted, and a clamping position in which it is
suitable for exerting grip on the outer side of said preformed part
(2, 3).
4. Holder tooling according to claim 2, wherein the lateral grip
member (27) includes a jaw (29) of shape that is complementary to
the portion of the preformed part (2, 3) with which it is
associated and against which it is suitable for coming into
engagement.
5. Holder tooling according to claim 2, wherein the lateral grip
member (27) is subdivided into a plurality of individual lateral
grip members that are distributed along the framework (31) along
its side extending in the extension direction of the hollow
structure (1) that is to be obtained.
6. Holder tooling according to claim 5, wherein the individual
lateral grip members (27) are individually mounted to move on the
framework (31).
7. Holder tooling according to claim 1, wherein the shape-holder
members comprise backing thrust members (25, 26) that are
individually mounted on one and/or the other of the frames (12, 13)
via position-adjustment means.
8. Holder tooling according to claim 7, wherein the backing thrust
members (25, 26) are distributed at least along a pair of length
members (14, 15) forming part of each of the frames (12, 13), the
length members (14, 15) of the pair leaving between them a path
(16) for passing a welding tool towards the preformed parts placed
in overlap on the flanges of the section.
9. Holder tooling according to claim 1, wherein the clamping means
(21, 22) are arranged as deformable members that are movable
between said clamping position and an assembly position in which
they are suitable for being inserted inside the set of preformed
parts (2, 3) installed inside the framework (31).
10. Holder tooling according to claim 9, wherein the clamping means
(21, 22) are arranged as at least one inflatable bladder (24).
11. Holder tooling according to claim 10, wherein the clamping
means (21, 22) comprise a body (23) that is suitable for bearing
against said inside face of the preformed part (2, 3) and that
houses the bladder (24) suitable for bearing against said anvil
(19, 20).
12. Holder tooling according to claim 1, wherein the framework (31)
includes handle members (30) suitable for engaging overturning
means forming parts of a stand of a friction-welding machine.
13. Holder tooling according to claim 1, wherein the anvils (19,
20) are at least two in number, being associated with a single
section (4) and being suitable for being placed laterally on either
side thereof.
14. A method of implementing holder tooling according to claim 1,
wherein the method includes performing the following operations:
placing the section (4) in position on one of the frames (12, 13);
placing the anvil (19, 20) in position on said frame (12, 13)
beside the section (4) on the side allocated thereto; placing the
clamping means (21, 22) associated with said anvil (19, 20) on said
frame (12, 13) on its corresponding lateral side; docking the parts
for welding (2, 3) in succession against the section (4) by sliding
their corresponding walls at least under the anvil (19, 20) and
possibly also under the clamping means (21, 22) and over at least
one of the shape-holder members (25, 26); putting the other frame
(12, 13) in place and joining the frame together; and operating the
clamping means (21, 22).
15. A method according to claim 14, wherein the shape-holder
members comprise at least one lateral grip member (27) for gripping
an outer preformed part (2, 3) of the hollow structure (1) with
which it is associated, and wherein the method includes operating
said lateral grip means (27) prior to operating the clamping means
(21, 22).
16. A method according to claim 14, wherein the anvils (19, 20) are
at least two in number, being associated with a single section (4)
and being suitable for being placed laterally on either side
thereof, and wherein the method includes after the parts (2, 3, 4)
have been welded together in one of the large faces of the hollow
structure (1) that is to be obtained, turning the framework (31)
over in order to weld the parts (2, 3, 4) together in the other
large face of the hollow structure (1) that is to be obtained.
17. A method according to claim 14, wherein implementing the
clamping means (21, 22) consists in applying lateral thrust against
the anvil (19, 20) to cause the flanges (8, 9) of the section (4)
to bear against the corresponding edges of the preformed parts (2,
3), the shape-holder members (25, 26) constituting members
providing opposing thrust against which said preformed parts (2, 3)
are respectively pressed.
Description
FIELD OF THE INVENTION
[0001] The invention lies in the technical field of using
friction-welding to weld together various thin metal parts for
assembly. The invention provides holder tooling for holding said
parts to enable them to be friction-welded together, so as to
obtain a hollow structure such as an airfoil, a tail fin, or an
analogous hollow structure.
BACKGROUND OF THE INVENTION
[0002] Welding techniques include those performed by friction, such
as so-called "friction stir welding" (FSW). Such a technique is
advantageous for assembling together metal parts that are thin,
e.g. presenting thickness of less than about 1.5 millimeters (mm).
By way of example, such parts are constituted by plates, sheets, or
other analogous parts that are thin and of large dimensions in the
general plane in which they extend. The parts may be plane parts or
they may be shaped, and their edges that are used for welding them
together are considered as being generally plane in the welding
zone. In general terms, the friction-welding technique consists in
holding together the parts that are to be assembled by means of
specific tooling. More particularly, the parts are held adjacent
one another and pressing one against the other, e.g. in abutment so
as to put their corresponding edge faces into contact one against
the other, or with one of the edges of a first part overlapping the
edge of a second part. The first part is thicker than the second
part and it includes a rabbet or analogous feature for receiving
the corresponding edge of the second part.
[0003] With the parts held in position for welding by the tooling,
a chuck carrying a welding pin is used to cause the adjacent edges
of the part to be heated. The welding pin is provided with
roughness in relief formed at its free end remote from its end that
is engaged in the chuck. By way of example, this roughness in
relief is a thread or is the result of the free end of the welding
pin being given a section of polygonal shape. Putting the welding
pin into contact with the adjacent edges of the parts and then
moving it relative thereto serves to cause a bead of welding to be
formed, thereby assembling the parts together. The bead of welding
is obtained in the welding zone as a result of the parts heating
under the effect of the friction applied locally thereto by the
welding pin. This heating causes the materials constituting the
parts to take on a pasty state, which materials then mix together
by spreading. The parts are subsequently joined together by
continuous dynamic recrystallization of the material in the welding
zone.
[0004] In a first technique for holding the parts, their edges are
held pressed adjacently against an anvil by clamping or by some
other analogous technique. Clamping members press at least one of
the parts against opposing thrust received by one and/or the other
of the parts against an anvil. The term "anvil" is used to
designate any member suitable for forming a bearing surface or
analogous bearing member against which the parts are pressed by
clamping, whether directly or indirectly.
[0005] In a second technique for holding the parts, the edges of
the parts are held in their relative position by means of a pair of
spools bearing respectively against one and the other of the
opposite faces of the parts to be assembled together. More
particularly, a bottom spool is fitted with the welding pin
arranged as a threaded rod that is secured to a top spool. Clamping
the edges of the parts between the spools enables them to be docked
and held together in localized manner in the welding zone.
[0006] Furthermore, in the field of aviation, it is desirable to be
able to make a hollow structure that is made up of a plurality of
parts that are assembled together one after another. Such a hollow
structure constitutes in particular an airfoil, a tail unit, or
some other analogous hollow structure. For example, two component
parts of the hollow structure may be preformed by being folded in
half so as to enable them to be shaped, and they are abutted via a
third part that is arranged as a transversal section for
transversally stiffening the hollow structure. Each preformed part
presents a generally plane profile of the hollow structure, one of
the parts constituting a leading profile and the other a trailing
profile. The section has an I-shaped section or the like with end
flanges depending on the profile of the section. The section is
interposed between the facing edges of the leading profile and of
the trailing profile, said section being oriented orthogonally
relative to the general plane in which the preformed parts extend.
The flanges of the section include rabbets for receiving respective
corresponding edges of the parts, so as to make it easier to
position them relative to one another.
[0007] Traditionally, a riveting technique is used for assembling
the preformed parts with the section. Nevertheless, it is desirable
for the rivets to be flush with the outside face of the hollow
structure, and this is difficult to achieve when the desired
preformed parts are of small thickness, e.g. of thickness less than
about 1.5 mm. Although the friction welding assembly technique is
advantageous for use in assembling preformed parts with the
section, it is difficult to implement in this context. Applying the
welding pin against the edges of the preformed parts gives rise to
large tensions and vertical forces in the general plane in which
the parts extend. The quality and the reliability of the resulting
assembly are uncertain, and holding the preformed parts in shape
during the welding operation is difficult to achieve, particularly
since the hollow structure is made up of preformed parts that are
thin and that present a cross section of height that is small
relative to length in the general plane in which they extend.
[0008] The first above-mentioned holding technique is more
particularly suitable for use in assembling plane or curved parts
having adjacent edges that are held in abutment via their
corresponding edge faces, or else in overlap. The parts are held
firmly and effectively over their entire length throughout the
complete welding operation serving to form the bead of welding.
However, at present, that holder tooling is massive and although it
is effective for parts that are plane or curved, it is not suitable
in its current state for assembling together parts that enable a
hollow structure of the above-mentioned kind to be made.
[0009] The second above-mentioned technique for holding the parts
runs the risk of the parts overheating because they are engaged
between the spools and because of the resulting friction. When
assembling together parts of small thickness, thickness of the
order of less than 1.5 mm, such heating tends to give rise to local
spoiling of the properties of the material constituting the parts,
and can even make it impossible to obtain continuous dynamic
recrystallization of the resulting bead of welding. In addition,
localized holding of the preformed parts at their corresponding
edges does not guarantee that they are kept in shape, and therefore
does not guarantee that a hollow structure will be obtained that is
made up of the desired profiles.
[0010] Furthermore, document US 2004/050907 describes using a
plurality of anvils and pressure backing-tools in order to hold the
parts for assembly in position in the vicinity of the connection
that is to be made.
[0011] Document JP 10230375 describes using anvil systems so as to
avoid the parts moving apart during friction welding.
[0012] Document JP 11058038 describes a device that provides more
thorough holding of the structure. In contrast, document US
2005/045693 provides for localized holding of the parts.
[0013] Finally, document JP 61146430 provides for the use of two
frames.
OBJECT AND SUMMARY OF THE INVENTION
[0014] The object of the present invention is to propose tooling
for holding thin metal parts together to enable them to be
friction-welded to each other in order to construct a hollow
structure that constitutes in particular an airfoil, a tail unit,
or some other analogous hollow structure. The hollow structure is
made up in particular of preformed parts forming at least a leading
profile and a trailing profile, and it houses at least one section
providing transverse stiffening and an intermediate junction
between the preformed parts. More specifically, the proposed
tooling is of the kind making use of at least one anvil and of
shape-holder members for holding the parts against the anvil.
[0015] The present invention seeks more particularly to provide
such tooling that enables the axial forces to be taken up that
result from pressing the welding pin against the edges of the
parts, and that also serves to take up the lateral forces that
result from tensions induced in the parts during the welding
operation so as to avoid deforming the profiles of the resulting
hollow structure.
[0016] The present invention also seeks more particularly to
provide such tooling that is suitable for use in making a hollow
structure with a wall that is of small thickness, of the order of
less than 1.5 mm, and of an inside volume that is relatively small.
Such an inside volume corresponds to a hollow structure having
overall height of an order lying in the range 50 mm to 100 mm for a
width of an order lying in the range 300 mm to 600 mm and for a
length of an order lying in the range 2000 mm to 4000 mm. These
numbers are given by way of indication and they do not restrict the
scope of the present invention, but rather they illustrate the
difficulties that need to be overcome in applying the present
invention to holding parts in order to obtain a hollow structure
using a friction-welding technique between the parts. These
difficulties lie in particular in providing tooling that is as
compact as possible and that is suitable for use in forming such
hollow structures.
[0017] The present invention also seeks more particularly to
provide such tooling that is suitable for holding in shape
preformed parts while the welding operation is being performed in
order to guarantee that the hollow structure that is obtained has
the desired shape. The tooling must also make it possible to
accommodate the docking and thickness tolerances of the parts over
their entire length, without that affecting the quality of the
resulting bead of welding.
[0018] The present invention also seeks more particularly to
provide such tooling in which the operations needed to implement it
during the various successive steps of welding the parts together
are few in number and easy and quick to perform.
[0019] Broadly, the present invention consists in deciding to use
the technique of holding parts for a friction-welding operation
that consists in clamping the parts for welding together between
shape-holder members and at least one anvil. The choice of this
holding technique seeks to assemble the parts together in a manner
that is robust and reliable in spite of their small thickness, of
the order of less than 1.5 mm, via a welded joint that is of
constant quality along the welded-together parts because of the
reliable control achieved over the heat generated and because
continuous and stable dynamic recrystallization is obtained of the
bead of welding that is being made.
[0020] It is recalled that the parts for welding together are parts
that are arranged relative to one another so as to make up a hollow
structure after they have been welded in succession one to another.
These parts for welding are made up in particular of preformed
parts that provide the profile of the hollow structure that is to
be obtained and of at least one internal stiffening and junction
section intermediate between the preformed parts. In particular, at
the ends of its section, such a section includes flanges that are
suitable for receiving in overlap the corresponding edges of the
preformed parts so that they can be welded together. The section
preferably has an I-shaped cross section, or any other analogous
section that provides at least one middle web having said flanges
at its ends. Preferably, the flanges are of a thickness that is
greater than the thickness of the edges of the parts for welding
together, and they include rabbets receiving said edges so as to
enable them to be lap welded, using the "self-holding joint"
technique.
[0021] The empty inside of the hollow structure is used to receive
the anvil and clamping means that serve to press together the edges
of the parts for welding in a direction that corresponds to the
direction in which the welding pin applies pressure against the
parts during the friction-welding operation. The edges for welding
together are clamped between the anvil located inside the hollow
structure and the shape-holder members that are placed outside the
hollow structure, bearing against the outside face of the preformed
parts. This clamping is achieved by operating the clamping means
that are placed inside the hollow structure and that exert lateral
thrust against the anvil. The anvil is placed beside the section
and is held by lateral clamping between the section and the
clamping means that bear against the inside faces of the preformed
parts installed inside the framework. The clamping means make use
in particular of deformable means, such as inflatable bladders or
the like in order to make them easier to operate and also to make
it easier to assemble and disassemble the tooling. The shape-holder
members are carried by frames that are placed on either side of the
hollow structure that is to be obtained, on either side of the
general plane in which it extends. These frames include junction
means for joining them together, e.g. making use of co-operating
fastener members, so that together they constitute a framework that
houses in position all of the parts for welding together, holding
them by means of the shape-holder members. The shape-holder members
are preferably mounted to move on the framework so as to enable
their positions to be adjusted relative to the shape of the hollow
structure to be obtained. The section is installed on the frames by
means of the flanges with which it is provided. Each frame has a
pair of middle length-members that extend in the general direction
in which the hollow structure that is to be obtained extends, and
that leave between them a path for passing the welding pin.
[0022] Lateral grip members for gripping the preformed parts are
carried by the framework to hold the profile of the hollow
structure that is to be obtained in shape, while avoiding any
deformation of the preformed parts during the welding operation.
Such a grip member individually comprises a jaw of profile that is
complementary in shape to the profile of the outside portion of the
preformed part with which it is associated. The lateral grip
members are distributed along the framework in the general
direction in which the hollow structure that is to be obtained
extends.
[0023] The framework is suitable for being turned over so that the
welding operations can be performed firstly on one large face of
the hollow structure that is to be obtained and then on the other
large face, without any need to disassemble the part-holder
tooling.
[0024] According to a general definition of the present invention,
the proposed tooling is tooling for holding parts in order to
enable them to be friction-welded together in order to construct a
generally plane hollow structure. The hollow structure is more
particularly made up of a set of preformed parts that are
successively abutted via at least one internal stiffening section
of the hollow structure that is to be obtained. Such a hollow
structure is constituted in particular by an airfoil, a tail unit,
or some other analogous hollow structure. The section is
advantageously used as an intermediate junction part for joining
together the preformed parts, and it is provided at the ends of the
section with flanges for receiving the edges of the preformed parts
in overlap. The tooling includes at least one anvil suitable for
receiving the adjacent edges of the parts for welding together
pressed thereagainst, and reversible clamping means suitable for
subjecting said edges to opposing thrust between the anvil and
shape-holder members for the hollow structure, and more
particularly preformed parts installed inside the framework.
[0025] According to the present invention, such tooling is mainly
recognizable in that it comprises: [0026] a framework for receiving
the parts for welding together in their positions for forming the
hollow structure, the framework being subdivided into two frames
provided with reversible junction means for joining them together
in an assembled position on either side of the hollow structure
that is to be obtained, on either side of the general plane in
which it extends; [0027] said shape-holder members for holding the
preformed parts installed inside the framework, which members are
carried by the framework; [0028] at least one anvil suitable for
being placed inside the set of preformed parts installed inside the
framework, being placed laterally relative to the section, between
its flanges; and [0029] said clamping means suitable for being
placed inside the set of preformed parts installed inside the
framework, which clamping means are movable into a clamping
position in which they cause opposing thrust to be applied between
the anvil and the inside face of at least one preformed part
associated with the clamping means.
[0030] Preferably, the shape-holder members comprise at least one
lateral grip member for gripping an outer preformed part of the
hollow structure with which it is associated.
[0031] In particular, the lateral grip member is mounted on the
framework via movement means enabling it to move between a
disengaged position in which its grip on the preformed parts
associated therewith is capable of being interrupted, and a
clamping position in which it is suitable for exerting grip on the
outer side of said preformed part.
[0032] Preferably, the lateral grip member includes a jaw of shape
that is complementary to the portion of the preformed part with
which it is associated and against which it is suitable for coming
into engagement.
[0033] In a preferred embodiment, the lateral grip member is
subdivided into a plurality of individual lateral grip members that
are distributed along the framework along its side extending in the
extension direction of the hollow structure that is to be
obtained.
[0034] Preferably, the individual lateral grip members are
individually mounted to move on the framework. This subdivision of
the lateral grip member enables the clamping positions of
individual lateral grip members to be adjusted individually, with
the advantage of being able to accommodate tolerances in the
straightness of the edges of the preformed parts, and possibly also
variations in the thrust they receive in overlap against the
section.
[0035] Preferably, the shape-holder members comprise backing thrust
members that are individually mounted on one and/or the other of
the frames via position-adjustment means.
[0036] Advantageously, the backing thrust members are distributed
at least along a pair of length members forming part of each of the
frames, the length members of the pair leaving between them a path
for passing a welding tool towards the preformed parts placed in
overlap on the flanges of the section.
[0037] In an advantageous embodiment, the clamping means are
arranged as deformable members that are movable between said
clamping position and an assembly position in which they are
suitable for being inserted in floating manner inside the set of
preformed parts installed inside the framework. Such deformable
clamping means are constituted, for example, as at least one
inflatable bladder or analogous deformable member.
[0038] In a preferred embodiment of the clamping means, the
clamping means comprise a body that is suitable for bearing against
said inside face of the preformed part and that houses the bladder
suitable for bearing against said anvil.
[0039] Preferably, the framework includes handle members suitable
for engaging overturning means forming parts of a stand of a
friction-welding machine.
[0040] In particular, the anvils are at least two in number, being
associated with a single section and being suitable for being
placed laterally on either side thereof.
[0041] The present invention also provides a method of implementing
part-holder tooling as described above, the method being suitable
for allowing said parts to be friction-welded together in order to
obtain a hollow structure made up of said parts.
[0042] In general terms, the method consists in performing the
following operations: [0043] Placing the section in position on one
of the frames. This operation consists more particularly in placing
the section on one of the frames, in causing the corresponding
flange of the section to be carried between the length members that
are incorporated in said frame and that leave between them the path
for passing the welding pin. [0044] Placing the anvil in position
on said frame beside the section on the side allocated thereto.
Preferably, a pair of anvils is placed on the frame, these anvils
being disposed laterally on either side of the section, and more
particularly on either side of the web or the like that it
includes. [0045] Placing the clamping means associated with said
anvil on said frame on its corresponding lateral side. Preferably,
a pair of clamping means is placed on the frame, the clamping means
being disposed laterally relative to one of the anvils with which
they are associated. [0046] Docking the parts for welding in
succession against the section by sliding their corresponding walls
at least under the anvil and possibly also under the clamping means
and over at least one of the shape-holder members. This docking
corresponds in particular to causing the flanges of the section to
be overlapped by corresponding edges of a preformed part. Each
flange of the section includes an outer rabbet for receiving the
corresponding edge of a preformed part. Putting the preformed part
into place causes their corresponding outer faces to come into
contact with the corresponding backing thrust members with which
the frame is provided. [0047] Putting the other frame in place and
joining the frame together, in particular to form the framework.
The preformed parts are thus placed in position on one of the
frames, with the installation of the other frame enabling the
shape-holder members with which it is equipped, and more
particularly the backing thrust members, to be put into contact
with the corresponding outside faces of the preformed parts. [0048]
Operating the clamping means. This operation consists more
particularly in inflating the bladders so as to press the anvils
laterally against the section, causing bodies housing the bladders
to apply opposite thrust against the corresponding inside faces of
the preformed parts.
[0049] Preferably, the proposed method further includes the
operation consisting in operating said lateral grip means prior to
operating the clamping means.
[0050] Advantageously, the proposed method includes the additional
steps consisting, after the parts have been welded together in one
of the large faces of the hollow structure that is to be obtained,
in turning the framework over in order to weld the parts together
in the other large face of the hollow structure that is to be
obtained.
[0051] Preferably, implementing the clamping means consists in
applying lateral thrust against the anvil so as to cause the
flanges of the section to bear against the corresponding edges of
the preformed parts. In such a method, the shape-holder members
constitute backing thrust members against which said preformed
parts are respectively pressed under the effects of the section
being held in position and of the backing thrust being pressed
laterally by the clamping means respectively against the section
and against the inside faces of the preformed parts in the general
direction in which they extend.
BRIEF DESCRIPTION OF THE DRAWINGS
[0052] A preferred embodiment of the present invention is described
below with reference to the figures of the accompanying sheets, in
which:
[0053] FIG. 1 is an example of a hollow structure that is to be
obtained by joining together the various parts making it up by
friction-welding;
[0054] FIG. 2 is a detail of FIG. 1, showing the particular ways in
which an edge of one part for welding is arranged to overlap an
edge of another part;
[0055] FIGS. 3 and 4 are respectively exploded and assembled
perspective views of tooling for holding parts for welding together
in order to obtain a hollow structure as shown in FIG. 1; and
[0056] FIG. 5 is a section view of the holding tooling of FIGS. 3
and 4 having installed therein the various parts for welding
together.
MORE DETAILED DESCRIPTION
[0057] In FIG. 1, a hollow structure 1 is obtained from a plurality
of parts 2, 3, 4 that are welded to one another by friction. In the
embodiment shown, the hollow structure 1 is an airfoil that
presents a leading profile 5 and a trailing profile 6, and that
includes an internal stiffening section 4. This hollow structure 1
has an overall height of about 70 mm for a width of about 500 mm
and a length in its general extension plane of about 3000 mm. Two
parts 2 and 3 are preshaped respectively to form the leading
profile 5 and the trailing profile 6, and they are assembled
together via the section 4. With reference also to FIG. 2, the
section 4 is an I-shaped member made up of a web 7 provided at each
of its ends with a flange 8, 9 that is used for welding the section
4 to the corresponding edges of the preformed parts 2, 3. Each of
the flanges 8, 9 of the section 4 has rabbets 10, for receiving in
overlap the corresponding edges of the preformed parts 2, 3 using
the "self-holding joint" assembly technique. The preformed parts 2,
3 and the section 4 are assembled together by a weld bead using the
friction-welding technique whereby a welding pin heats the parts 2
and 4 and then the parts 3 and 4 for assembling together in
succession so as to cause material forming the weld bead to spread
and mix.
[0058] In FIGS. 3 to 5, tooling is organized for holding the parts
2, 3, 4 making up the hollow structure 1 shown in FIG. 1 for the
purpose of performing all of the welding operations needed to
obtain said hollow structure 1. The tooling is arranged to enable
all of these welding operations to be performed starting from a
single installation of the parts 2, 3, 4 making up the hollow
structure 1 on said tooling. This installation can be performed
quickly and easily, with the parts 2, 3, 4 being accurately
positioned relative to one another, while nevertheless taking
account of docking tolerances between the parts 2, 3, 4 and any
possible variations in their thicknesses. In addition, the tooling
serves to hold the hollow structure 1 in shape in spite of the
forces and tensions to which it is subjected during the various
welding operations, as results in particular from pressing the
welding pin against the parts 2, 3, 4 and from the heat given off
by forming the weld beads.
[0059] The tooling comprises two frames 12, 13 that make up a
framework 31 for receiving the parts 2, 3, 4 for welding together
in their positions for forming the hollow structure 1. These frames
12, 13 are generally rectangular, each having middle length-members
14, 15 extending in the general extension direction of the hollow
structure 1 to be obtained. For each of the pairs of length members
14, 15, a path 16 is provided for passing the welding pin between
the length members 14, 15 so as to enable the pin to be pressed
against the edges of the parts 2, 3, 4 for welding together. The
frames 12, 13 are suitable for being placed on either side of the
hollow structure 1 that is to be obtained, on either side of its
general extension plane, and they are provided with junction means
17, 18 for joining them together, which means are constituted by
co-operating fastener members, for example.
[0060] A pair of anvils 19, 20 is fitted inside the preformed parts
2, 3 placed in their welding positions on the framework 31. This
pair of anvils 19, 20 may be constituted by anvils that are
structurally distinct or by a one-piece unit, in which case the
anvils 19, 20 are connected together at their ends in a zone lying
outside the zone in which the weld beads are formed. More
particularly in FIG. 5, the anvils 19, 20 are placed on either side
of the web 7 of the section 4 in order to exert lateral thrust
thereagainst so as to hold it in position. This lateral thrust is
applied by using clamping means 21, 22 located respectively on
opposite sides of the anvils 19, 20 on their sides remote from the
sides that thrust against the web 7 of the section 4. These
clamping means 21, 22 comprise a body 23 that houses an inflatable
bladder 24. Each frame 12, 13 carries backing thrust members 25, 26
against which the preformed parts 2, 3 press when the clamping
means 21, 22 are put into operation. These backing thrust members
25, 26 are members that comprise a set of members for holding the
hollow structure that is to be obtained in shape. Inflating the
bladders 24 causes them to be pressed against the corresponding
anvils 19, 20 and causes an opposing thrust to be applied by the
bodies 23 against the inside faces of the preformed parts 2, 3 with
which they are associated. The preformed parts 2, 3 are clamped
between the clamping means 21, 22 and more particularly between the
body 23 and the backing thrust members 25, 26 that are carried by
the frames 12, 13. The backing thrust members 25, 26 are carried in
particular by the middle length members 14, 15 forming parts of the
frames 12, 13, being positioned to correspond with the bearing
zones occupied by the body 23 of each of the clamping means 21, 22
against the inside faces of the corresponding preformed parts 2,
3.
[0061] The framework 31 is provided with lateral grip members 27
for gripping the preformed parts 2, 3, which members are disposed
along the framework 31 along its side corresponding to the general
extension of the hollow structure 1 that is to be obtained. These
lateral grip members 27 are members forming part of the set of
members for holding the hollow structure 1 that is to be obtained
in shape. These lateral grip members 27 are constituted by a
plurality of individual lateral grip members that are mounted on
the framework 31 via individual movement means 28. The lateral grip
members 27 are movable between a disengaged position enabling the
preformed parts 2, 3 to be installed on the framework 31, and a
clamping position in which the lateral grip members 27 engage the
ends of the preformed parts 2, 3. Each lateral grip member 27 has a
jaw 29 of shape that is complementary to the portion of the
preformed parts 2, 3 with which it comes into engagement. While the
welding operations are being performed, the preformed parts 2, 3
are held in shape on the framework 31 by the combination of thrust
exerted against them by the shape-holder members, comprising the
backing thrust members 25, 26 and the lateral grip members 27.
[0062] In FIG. 4, the framework 31 is fitted with handle members 30
enabling it to be turned over. These handle members 30 serve, after
welding operations have been preformed on one of the faces of the
hollow structure 1 that is to be obtained, to turn the framework 31
over and allow welding operations to be performed on the other face
of the hollow structure 1. Turning the structure over in this way
serves more particularly to enable all of the operations of welding
the parts 2, 3, 4 together to be preformed so as to obtain the
hollow structure 1 without it being necessary to remove the parts
2, 3, 4 from the holder tooling.
* * * * *