U.S. patent application number 11/791879 was filed with the patent office on 2007-11-15 for installation for welding frameworks of nuclear fuel assemblies, programming method, corresponding methods for framework welding and assembling.
This patent application is currently assigned to SOCIETE FRANCO-BELGE DE FABRICATION DE COMBUSTIBLE. Invention is credited to Thierry Taillandier.
Application Number | 20070263760 11/791879 |
Document ID | / |
Family ID | 34951996 |
Filed Date | 2007-11-15 |
United States Patent
Application |
20070263760 |
Kind Code |
A1 |
Taillandier; Thierry |
November 15, 2007 |
Installation for Welding Frameworks of Nuclear Fuel Assemblies,
Programming Method, Corresponding Methods for Framework Welding and
Assembling
Abstract
The installation provided includes at least one structure for
receiving and holding guide tubes and structural elements; a
carriage movable parallel to the guide tubes; at least one welding
tool; and displacement means for moving the welding tool, the
displacement means connecting the pincer to the carriage and
presenting at least six degrees of freedom.
Inventors: |
Taillandier; Thierry; (St.
Paul Les Romans, FR) |
Correspondence
Address: |
DAVIDSON, DAVIDSON & KAPPEL, LLC
485 SEVENTH AVENUE, 14TH FLOOR
NEW YORK
NY
10018
US
|
Assignee: |
SOCIETE FRANCO-BELGE DE FABRICATION
DE COMBUSTIBLE
Tour Areva, 1 Place de la Coupole
Courbevoie
FR
92400
|
Family ID: |
34951996 |
Appl. No.: |
11/791879 |
Filed: |
November 30, 2005 |
PCT Filed: |
November 30, 2005 |
PCT NO: |
PCT/FR05/02984 |
371 Date: |
May 30, 2007 |
Current U.S.
Class: |
376/261 ;
700/245; 901/42 |
Current CPC
Class: |
G21C 3/334 20130101;
B23K 9/1272 20130101; Y10S 901/42 20130101; G21C 21/00 20130101;
Y02E 30/40 20130101; Y02E 30/30 20130101 |
Class at
Publication: |
376/261 ;
700/245; 901/042 |
International
Class: |
G21C 19/00 20060101
G21C019/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 30, 2004 |
FR |
0412707 |
Claims
1 to 14. (canceled)
15. An installation for welding structural elements onto guide
tubes of a nuclear fuel assembly skeleton, the installation
comprising: at least one structure for receiving and holding guide
-tubes and structural elements; a carriage movable parallel to the
guide tubes; at least one welding tool; and displacement means for
moving the welding tool, the displacement means connecting the
welding tool to the carriage and presenting at least six degrees of
freedom.
16. An installation according to claim 15, wherein the displacement
means present at least seven degrees of freedom.
17. An installation according to claim 15, wherein the displacement
means comprise an arm having at least two segments articulated one
to another, and wherein the displacement means further comprise a
wrist that carries the welding tool, the wrist extending the arm
and being articulated to the arm via a connection presenting at
least two degrees of freedom.
18. An installation according to claim 17, wherein the wrist is
articulated to the arm by a connection enabling movement in
rotation about at least two distinct axes.
19. An installation according to claim 17, wherein the arm
comprises at least three segments articulated one to another.
20. An installation according to claim 17, wherein the at least two
segments of the arm are articulated one to another via respective
connections allowing movement in rotation about two distinct
axes.
21. An installation according to claim 15, wherein the displacement
means comprise a support box movable transversely to the guide
tubes.
22. An installation according to claim 15, wherein the carriage is
mounted to move on the structure.
23. An installation according to claim 15, wherein the welding tool
is a resistance-welding pincer.
24. An installation according to claim 15, further comprising a
programmable controller controlling the displacement means for
moving the welding tool, and a manual controller controlling the
displacement means for moving the welding tool.
25. An installation according to claim 24, wherein the displacement
means include position sensors.
26. A method of programming an installation according to claim 24,
the method comprising the steps of: manually controlling the
displacement means so that the welding tool executes a welding
sequence; and recording the welding sequence in the programmable
control means.
27. A method of welding a nuclear fuel assembly skeleton, the
skeleton comprising guide tubes and structural elements welded to
the guide tubes, the method comprising the steps of welding
structural elements to the guide tubes using an installation
according to claim 15.
28. A method of making a nuclear fuel assembly, the assembly
comprising nuclear fuel rods and a skeleton for supporting the
rods, the skeleton comprising guide tubes and structural elements
welded to the guide tubes, the method using a skeleton welding
method according to claim 26.
29. An installation for welding structural elements onto guide
tubes of a nuclear fuel assembly skeleton, the installation
comprising: at least one structure for receiving and holding guide
tubes and structural elements; a carriage movable parallel to the
guide tubes; at least one welding tool; and a connector connecting
the welding tool to the carriage and capable of moving the welding
tool with at least six degrees of freedom.
Description
[0001] The present invention relates to an installation for welding
structural elements onto guide tubes of a nuclear fuel assembly
skeleton, the installation comprising: [0002] at least one
structure for receiving and holding guide tubes and structural
elements; [0003] a carriage movable parallel to the guide tubes;
[0004] at least one welding tool; and [0005] displacement means for
moving the welding tool, the displacement means connecting the
pincer to the carriage and presenting at least five degrees of
freedom.
[0006] The invention applies in particular to welding grids for
holding nuclear fuel rods.
[0007] FR-2 670 947 discloses an installation of the
above-specified type that enables grids to be welded that are
provided with welding tongues projecting from the top faces of the
grids. The displacement means of the welding installation comprise
a support box that is movable transversely relative to the guide
tubes, a vertically-extensible arm, and a steerable wrist that
carries a welding pincer. The steerable wrist is capable of moving
in rotation about three distinct axes, such that the welding pincer
presents a total of six degrees of freedom. The above-described
installation makes it possible to achieve high rates of welding
throughput, but it is still desirable to increase those rates.
[0008] U.S. Pat. No. 4,587,394 also discloses a welding
installation, which installation has four welding tools moving
simultaneously so that each contributes to welding grids to the
guide tubes of a given skeleton. Each tool is connected to a
carriage that is movable longitudinally relative to the guide tubes
by displacement means that present three degrees of freedom.
Although the four welding tools move simultaneously, the rates of
throughput achieved by such a welding installation are likewise
found to be too slow.
SUMMARY OF THE INVENTION
[0009] An object of the invention is to solve that problem by
providing an installation of the above-specified type that makes it
possible to achieve faster rates of welding.
[0010] To this end, the invention provides an installation for
welding structural elements onto guide tubes of a nuclear fuel
assembly skeleton, the installation comprising: [0011] at least one
structure for receiving and holding guide tubes and structural
elements; [0012] a carriage movable parallel to the guide tubes;
[0013] at least one welding tool; and [0014] displacement means for
moving the welding tool, the displacement means connecting the
welding tool to the carriage and presenting at least five degrees
of freedom; [0015] the installation being characterized in that the
displacement means present at least six degrees of freedom.
[0016] The invention also provides a programming method.
[0017] The invention also provides a method of welding a nuclear
fuel assembly skeleton.
[0018] The invention also provides a method of making a nuclear
fuel assembly.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] The invention can be better understood on reading the
following description given purely by way of example and made with
reference to the accompanying drawings, in which:
[0020] FIG. 1 is a diagrammatic perspective view showing a welding
installation of the invention, the structure for receiving the
skeletons not being shown;
[0021] FIG. 2 is a diagrammatic face view of the FIG. 1
installation, seen looking along the direction of arrow II in FIG.
1;
[0022] FIG. 3 is a fragmentary diagrammatic view in perspective
showing a portion of the skeleton of a nuclear fuel assembly that
can be welded by the installation of FIG. 1;
[0023] FIGS. 4 and 5 are fragmentary diagrammatic views in
perspective showing the means for moving the welding tool in the
installation of FIGS. 1 and 2; and
[0024] FIG. 6 is a fragmentary diagrammatic view in perspective
showing a welding installation in another embodiment.
DETAILED DESCRIPTION
[0025] FIGS. 1 and 2 are diagrams showing an installation 1 for
welding structural elements onto guide tubes of nuclear fuel
assembly skeletons.
[0026] More precisely, the structural elements considered below are
grids for holding nuclear fuel rods, even though other structural
elements, such as sleeves, could also be welded by the installation
1.
[0027] With reference to FIG. 3, it is recalled that a fuel
assembly 2 mainly comprises nuclear fuel rods 3 and a structure or
skeleton 4 for supporting the rods 3.
[0028] Conventionally, the support skeleton comprises: [0029] a
bottom nozzle 5 and a top nozzle 6 disposed at the longitudinal
ends of the assembly 1; [0030] guide tubes 7 for receiving the rods
of a cluster (not shown) for controlling and stopping the nuclear
reactor; and [0031] grids 8 for holding the rods 3.
[0032] The nozzles 5 and 6 are secured to the longitudinal ends of
the guide tubes 7.
[0033] The rods 3 extend vertically between the nozzles 5 and 6.
The rods 3 are disposed at the nodes of a substantially regular
square-based array in which they are held by the grids 8. Some of
the nodes of the array are occupied by the guide tubes 7, and
possibly by a central tube for instrumentation purposes.
[0034] Conventionally, the grids 8 comprise sets of crossed plates
that define between them cells that are centered on the nodes of
the regular array. Most of the cells are for receiving a respective
fuel rod 3. Each of the other cells receive a guide tube 7, and the
central cell optionally receives an instrumentation tube 14.
[0035] Usually, the grids 8 are provided with welding tabs that
project upwards and that enable the grids 8 to be welded to the
guide tubes 7. There are also exist grids that do not have such
tabs, as shown in U.S. Pat. No. 4,849,161. The double plates of the
grid in that document then present top setbacks defining zones for
welding the grid to the guide tubes 7.
[0036] Like the installation of document FR-2 670 947, the
installation 1 of FIGS. 1 and 2 comprises an assembly bench 10
suitable for being covered laterally by protective panels. The
bench 10 is constituted by a metal gantry comprising uprights and
two horizontal longitudinal rails 11 on which there travels a
carriage 12 carrying a welding robot 13.
[0037] The bench 10 defines two parallel work zones (FIG. 2), each
at least as long as a skeleton 4 for welding, and disposed side by
side. In each of the zones there is placed a structure 14 enabling
a skeleton 4 to be preassembled thereon. Each structure 14 extends
parallel to the rails 11 and may comprise a machine-welded table 16
with a surface slab 18.
[0038] As shown in FIG. 2, the bench 10 also has rails 22 disposed
transversely to the rails 11 and enabling a cage 24 to move between
the position in which it is shown in FIG. 2, where it is facing one
of the structures 14, and another position where it is facing the
other structure 14. The cage 24 is provided with longitudinal rails
on which there travels a carriage 25 for positioning expandable
mandrels that are to be inserted in the guide tubes 7 at the
welding locations in order to prevent the tubes becoming deformed.
These mandrels may have the structure as already described in
document FR-A-2 533 353 and they may be guided by frames carried by
the cage (not shown).
[0039] The surface slab 18, which extends over the entire length of
the structure 14, is designed to receive, at adjustable locations,
frames 20 for positioning and holding the grids 8 of the skeleton
that is to be welded. These frames 20, are provided with means
enabling them to be opened in order to insert a grid 8 and enabling
them to be reclosed, and they may be of conventional structure. In
the example shown, the frames 20 for receiving the grids 8 of a
skeleton 4 have their diagonals extending horizontally and
vertically.
[0040] The carriage 12 occupies the entire width of the assembly
bench and carries at least one transverse rail 34.
[0041] The welding robot 13 has a resistance welding pincer 36 and
displacement means 38 for moving the welding pincer 36 that connect
the pincer 36 to the carriage 12.
[0042] The displacement means 38 comprise: [0043] a support box 40
that is movable transversely on the rail(s) 34; [0044] an
articulated arm 42 extending the support box 40 downwards; and
[0045] a steerable wrist 44 extending the arm 42 and carrying the
welding pincer 36.
[0046] The support box 40 may contain the welding transformer for
feeding electricity to the welding pincer 36.
[0047] By means of the carriage 12, it is possible to move the
welding pincer 36 relative to the bench 10 in translation in the X
direction as represented by double-headed arrow A in FIG. 1, i.e.
parallel to the guide tubes 7 of a skeleton placed on a structure
14. Because of the support box 40, it is also possible to move the
pincer 36 in translation along the Y direction, i.e. transversely
relative to the guide tubes 7, as represented by double-headed
arrow B in FIG. 1.
[0048] As shown in FIGS. 4 and 5, the arm 42 comprises three
successive segments 46, 48, and 50. The first segment 46 extends
the support box 40 downwards. The second segment 48 is articulated
to the first segment 46 via a double rotary connection enabling
both rotary movement about a vertical axis, as represented by
double-headed arrow C in FIG. 4, and rotary movement about a
horizontal axis, as represented by double-headed arrow D in FIGS. 4
and 5.
[0049] The third segment 50 is articulated to the second segment 48
of the arm 42 by a double rotary connection enabling both relative
rotary movement about a horizontal axis as represented by
double-headed arrow E in FIG. 5, and relative rotary movement about
the longitudinal axis of the third segment 50, as represented by
double-headed arrow F in FIGS. 4 and 5.
[0050] The wrist 44 carries the case 52 of the welding pincer 36.
The case 52 is provided with the usual electrical and pneumatic
power supply means, constituted by cables. The wrist 44 is
connected to the third segment 50 of the arm 42 via a double rotary
connection enabling both relative rotary movement about an axis
that is orthogonal to the longitudinal axis of the third segment
50, as represented by double-headed arrow G in FIGS. 4 and 5, and
rotary movement about the longitudinal axis of the pincer 36, as
represented by double-headed arrow H in FIGS. 4 and 5.
[0051] Thus, the welding pincer 36 presents eight degrees of
freedom represented by arrows A to H, with the displacement means
38 providing seven of them.
[0052] As shown in FIG. 2, the installation 1 further includes
programmable means 54 for controlling the displacement and the
operation of the pincer 36. By way of example, these control means
54 comprise a computer having one or more processors, data storage
means 56, input and output means, and display means (not
shown).
[0053] The input/output means comprise, for example, a user
interface, e.g. in the form of a controller 58 enabling the welding
pincer 36 to be moved and operated under manual control.
[0054] In order to program the control means 54, which means are
intended subsequently to control the operation of the welding
pincer 36 automatically, it is possible to proceed as follows, by
way of example.
[0055] An operator uses the controller 58 to control the
displacement of the pincer 36 manually until it reaches a first
location for welding a first grid 8 to one of the guide tubes 7 of
a skeleton 4 that has been preassembled on one of the structures
14, and then the operator causes a welding operation to be
performed at this location. The electrodes of the pincer 36 then
press the corresponding zone 9 of the grid 8 against the guide
tubes 7 in question, thus performing welding by resistance. The
coordinates of this first welding location, e.g. delivered by
position sensors 60 present in the displacement means 38 are then
recorded in the storage means 56. Conventional sensors are shown
very diagrammatically in FIG. 1.
[0056] Thereafter, the operator continues with the welding sequence
for all of the first grid 8 in question, the storage means 56
progressively recording the coordinates of the various locations
where welding is performed, and also the positions of the pincer 36
during those welding operations. This sequence for welding a grid 8
is merely a portion of the complete sequence for welding the
skeleton 4, and it is therefore referred to below as a
"sub-sequence".
[0057] Thereafter, the operator brings the pincer 36 to the first
location for welding a second grid 8 to the guide tubes 7 of the
skeleton 4. The operator can then trigger execution of the welding
sub-sequence as previously carried out manually on the first grid 8
and recorded.
[0058] By proceeding in this way for each of the grids 8, the
storage means 56 record the data needed for performing all of the
welding operations that need to be performed on all of the grids
present along the guide tubes 7.
[0059] This complete sequence for welding the grids 8 of a skeleton
4 is then stored and can be executed automatically when a skeleton
4 of the same type is to be welded by the installation, with the
operator then needing only to position the pincer 36 on the first
location for welding the first grid 8 and then triggering execution
of the entire sequence.
[0060] It is also possible to store, e.g. in the same manner as
described above, complete sequences in the storage means 56 for
welding skeletons of other types.
[0061] This programming method, based on recording a training
sequence carried out under manual control, is very user-friendly
and can be implemented very quickly. In particular, it is less
time-consuming than prior art methods that require all of the
coordinates of all of the welding positions to be defined one by
one. Nevertheless, programming in ways other than that described
above can also be used with the installation 1. Conversely, this
programming technique by training can be used with an installation
1 in which the number of degrees of freedom for the pincer 36 is
arbitrary, e.g. six as in FR-2 670 977.
[0062] It should also be observed that the complete programmed
welding sequences may include sub-sequences that are different for
some of the grids 8, and also a sub-sequence for welding guide
tubes to one of the nozzles 5 or 6 or to connection elements
belonging to one of the nozzles 5 or 6.
[0063] Because of the numerous degrees of freedom presented by the
pincer 36, it has been found that welding sequences can be
performed much more quickly than in the prior art. Surprisingly, it
is better to increase the number of degrees of freedom than to
increase the number of welding tools.
[0064] This is because shorter paths can be followed between the
various welding locations.
[0065] In addition, because of the extra degrees of freedom in
rotation, and in particular because of the possibility of rotating
about a horizontal axis as represented by double-headed arrow D,
the pincer 36 can move at speeds that are very high, and in
particular greater than 13 meters per second (m/s).
[0066] In addition, because of the large number of degrees of
freedom, the pincer 36 can reach zones that are difficult of
access, and in particular zones for welding grids of the kind
disclosed in U.S. Pat. No. 4,849,161. The installation 1 can
therefore be used for welding grids 8 of all types, and in
particular grids that do not present any welding tabs.
[0067] Furthermore, the pincer is capable of applying high welding
forces, e.g. of the order of 60 decanewtons (daN), even in
locations that are difficult of access.
[0068] As in FR-2 670 947, the presence of two structures 14 makes
it possible to use one for preassembling a skeleton while the other
one is being used with the pincer 36 to weld together the elements
of a skeleton 4 that has already been preassembled. By operating in
parallel in this way, the welding robot 13 is used on an almost
continuous basis.
[0069] Nevertheless, in certain variants, the installation 1 could
have only one structure 14.
[0070] In general, the displacement means 48 can present fewer
degrees of freedom, for example only seven.
[0071] Similarly, the degrees of freedom are not necessarily those
described above. It is possible to envisage using combinations of
movements in rotation and in translation other than those described
above.
[0072] FIG. 6 shows another embodiment of a welding installation 1
that differs from that described above mainly as follows.
[0073] The gantry 10 is mounted to slide on the structure 14 that
receives a skeleton for welding. The support box 40 is secured to
the top web 62 of the gantry 10 and therefore does not present any
degree of freedom relative thereto. The double-headed arrow B of
the above-described embodiment is therefore not shown in FIG.
6.
[0074] The connection between the segments 48 and 50 of the arm 42
is a simple rotary connection, represented by double-headed arrow
E. The connection between the segment 50 and the wrist 44 is a
triple rotary connection, represented by double-headed arrows F to
H.
[0075] The displacement means 38 for moving the tool 36 thus
present six degrees of freedom represented by the arrows C to
H.
[0076] Mounting the gantry 10 on the structure 14 thus enables one
degree of freedom to be eliminated, specifically the degree of
freedom represented by the arrow B in the above figures.
[0077] In addition, mounting the gantry 10 on the structure 14
improves the positioning of the tool 36 relative to a skeleton for
welding.
[0078] It should be observed that this characteristic can be used
independently of the number of degrees of freedom of the
displacement means 38.
[0079] Thus, a welding installation 1 may have a gantry 10 slidably
mounted on a structure 14, without its displacement means 38
presenting at least six degrees of freedom.
[0080] In general, the welding tool 36 can implement welding of
some type other than resistance welding.
* * * * *