U.S. patent application number 13/812861 was filed with the patent office on 2013-05-23 for device for insertion, guidance and evacuation of cylindrical parts such as nuclear fuel pellets, in a centreless grinder.
This patent application is currently assigned to AREVA NC. The applicant listed for this patent is Serge Fantini, Herve Medina. Invention is credited to Serge Fantini, Herve Medina.
Application Number | 20130130602 13/812861 |
Document ID | / |
Family ID | 43828228 |
Filed Date | 2013-05-23 |
United States Patent
Application |
20130130602 |
Kind Code |
A1 |
Fantini; Serge ; et
al. |
May 23, 2013 |
Device For Insertion, Guidance And Evacuation Of Cylindrical Parts
Such As Nuclear Fuel Pellets, In A Centreless Grinder
Abstract
The invention relates to a device (1) for the insertion,
guidance and evacuation of cylindrical parts to be ground in a
centreless grinder (10). According to the invention, micrometric
means (4, 40, 41) for adjustment of the alignment of the guides at
the entry (3) to and the exit (5) from the guide chute (2) are
provided and these micrometric adjustment means are independent
from each other. The invention enables very precise adjustment of
the alignment and prevents any shift of the parts.
Inventors: |
Fantini; Serge; (Saint
Genies De Comolas, FR) ; Medina; Herve; (Saint Genies
De Comolas, FR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Fantini; Serge
Medina; Herve |
Saint Genies De Comolas
Saint Genies De Comolas |
|
FR
FR |
|
|
Assignee: |
AREVA NC
Paris
FR
|
Family ID: |
43828228 |
Appl. No.: |
13/812861 |
Filed: |
July 25, 2011 |
PCT Filed: |
July 25, 2011 |
PCT NO: |
PCT/EP11/62748 |
371 Date: |
January 28, 2013 |
Current U.S.
Class: |
451/340 ;
451/364 |
Current CPC
Class: |
B24B 5/36 20130101; B24B
5/355 20130101; B24B 41/005 20130101; Y02E 30/30 20130101; B24B
5/225 20130101; G21C 21/02 20130101; B24B 5/22 20130101; B24B 5/313
20130101 |
Class at
Publication: |
451/340 ;
451/364 |
International
Class: |
B24B 5/36 20060101
B24B005/36; B24B 5/22 20060101 B24B005/22 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 27, 2010 |
FR |
10 56138 |
Claims
1. Device for the insertion, guidance and evacuation of cylindrical
parts such as nuclear fuel pellets, in a centreless grinder,
comprising: an insertion guide chute adapted to guide said
cylindrical parts over the length of the grinding wheel and drive
wheel of a centreless grinder, a first guide, called the entry
guide, arranged at one longitudinal end of the guide chute and
adapted to allow the insertion of cylindrical parts one by one onto
the guide chute from a conveyor system on the entry side of the
centreless grinder, mechanical means for micrometric adjustment of
the entry guide relative to the guide chute, a second guide, called
the exit guide, arranged at the other longitudinal end of the guide
chute and adapted to transfer parts from the chute to a conveyor
system on the exit side from the centreless grinder, mechanical
means for micrometric adjustment of the alignment of the exit guide
relative to the guide chute, wherein the mechanical means for
micrometric adjustment of the alignment of the entry guide are
independent from the micrometric alignment means of the exit
guide.
2. Device according to claim 1, in which the guide chute is a
single piece part made of XC 38 steel, on which surface and in-core
annealing and quenching heat treatments have been made and
preferably surface treatments once the guide chute has been
finished.
3. Device according to claim 1, in which at least one of the two
guides is composed of two strips one of which is fixed and parallel
to the longitudinal edge of the chute and the other is installed on
a pivot that adjusts the space from the fixed guide facing it, the
distance from the pivoting guide being varied by actuation of
mechanical means for adjusting the alignment of said guide.
4. Device according to claim 3, in which the entry guide and the
exit guide are each composed of two strips, one of which is fixed
and parallel to a longitudinal edge of the chute and the other is
free to pivot to adjust the spacing of the guide from the fixed
guide facing it.
5. Device according to claim 3, in which the pivoting strip of the
two guides is installed pivoting about an axis fitted with a
polymer bearing.
6. Device according to claim 4, in which: the pivot axis of the
pivoting strip of the entry guide and/or the exit guide is (are)
mounted in a support, the mechanical micrometric means for
adjustment of the alignment of the entry guide relative to the
guide chute and/or the mechanical adjustment means of the exit
guide comprise a first screw screwed into the pivot axis support
and a second screw nested into the first screw, with a smaller
pitch than the first screw and adapted to bear in contact with a
part of the pivoting strip, screwing of the first screw into the
support causing translation of the two screws while screwing the
second screw into the first screw and bearing in contact with the
part of the pivoting strip causes pivoting of the pivoting
strip.
7. Device according to claim 6, in which the pitch of the second
screw is smaller than but sufficiently close to the pitch of the
first screw to create a micrometric adjustment of the pivoting
strips.
8. Device according to claim 6, comprising a spring adapted to
compensate for functional clearances of the device by guaranteeing
permanent bearing between the second screw and the pivoting
strip.
9. Device according to claim 7, in which each pivot axis and screw
axis support is fixed to the guide chute.
10. Device according to claim 7, in which each pivot axis and screw
axis support is shaped in a turret with the two screws nested in
each other and arranged in the upper part of the turret.
11. Device according to claim 1, in which the geometric shape and
the length of the exit guide are adapted to limit the number of
ground cylindrical parts buffered at the exit from the wheels.
12. Device according to claim 1, forming a single piece assembly to
which adapted handles are fixed to enable its insertion into and
removal from a centreless grinder.
13. Centreless grinder comprising: an insertion guide chute adapted
to guide said cylindrical parts over the length of the grinding
wheel and drive wheel of a centreless grinder, a first guide,
called the entry guide, arranged at one longitudinal end of the
guide chute and adapted to allow the insertion of cylindrical parts
one by one onto the guide chute from a conveyor system on the entry
side of the centreless grinder, mechanical means for micrometric
adjustment of the entry guide relative to the guide chute, a second
guide, called the exit guide, arranged at the other longitudinal
end of the guide chute and adapted to transfer parts from the chute
to a conveyor system on the exit side from the centreless grinder,
mechanical means for micrometric adjustment of the alignment of the
exit guide relative to the guide chute, wherein the mechanical
means for micrometric adjustment of the alignment of the entry
guide are independent from the micrometric alignment means of the
exit guide.
14. Centreless grinder according to claim 13, adapted to grinding
of nuclear fuel pellets (P).
15. Glove box in which a centreless grinder is arranged according
to claim 13.
16. Device for the insertion, guidance and evacuation of
cylindrical parts such as nuclear fuel pellets, in a centreless
grinder, comprising: an insertion guide chute adapted to guide said
cylindrical parts over the length of the grinding wheel and drive
wheel of a centreless grinder, a first guide, called the entry
guide, arranged at one longitudinal end of the guide chute and
adapted to allow the insertion of cylindrical parts one by one onto
the guide chute from a conveyor system on the entry side of the
centreless grinder, a first plurality of screws for micrometric
adjustment of the entry guide relative to the guide chute, a second
guide, called the exit guide, arranged at the other longitudinal
end of the guide chute and adapted to transfer parts from the chute
to a conveyor system on the exit side from the centreless grinder,
a second plurality of screws for micrometric adjustment of the
alignment of the exit guide relative to the guide chute, wherein
the first plurality of screws for micrometric adjustment of the
alignment of the entry guide are independent from the second
plurality of screws for micrometric alignment means of the exit
guide.
17. Device according to claim 15, in which the first plurality of
screws and/or the second plurality of screws comprise a first screw
and a second screw nested into the first screw.
Description
TECHNICAL FIELD
[0001] The invention relates to a device for the insertion,
guidance and evacuation of cylindrical parts such as nuclear fuel
pellets in a centreless grinder.
[0002] It is particularly aimed at improving the reliability of
centreless grinding.
[0003] The main application is grinding of nuclear fuel pellets for
which quality is strict and imposes requirements to avoid
generating defects on the pellets.
PRIOR ART
[0004] Centreless grinding is a known advantageous grinding process
for grinding cylindrical parts, particularly for nuclear fuel
pellets.
[0005] A centreless grinder usually includes two grinding wheels,
one of which is a drive wheel used to rotate the pellets on
themselves and making them advance on a guide rail called the guide
chute in the case of nuclear fuel pellets, and the other is a
grinding wheel with the function of grinding the pellet diameters
by abrasion.
[0006] Obviously, the quality of ground nuclear fuel pellets
depends on the efficiency of the centreless grinder itself, but
also on the quality of the pellet transfer immediately on the entry
side into the centreless grinder, in it, and immediately on the
exit side from it, in other words the quality of insertion of
pellets into the guide chute, of their guidance in the guide chute
between the grinding wheel and the drive wheel and of their
evacuation from the drive wheel when they have been ground.
[0007] The general purpose of the invention is to propose a
solution to further improve the transfer quality of cylindrical
parts such as nuclear fuel pellets, immediately on the entry side
into a centreless grinder, in it and immediately on its exit
side.
[0008] One particular purpose is to propose a solution that is easy
to use in a glove box environment.
PRESENTATION OF THE INVENTION
[0009] To achieve this, the purpose of the invention is a device
for the insertion, guidance and evacuation of cylindrical parts
such as nuclear fuel pellets, in a centreless grinder
comprising:
[0010] an insertion guide chute adapted to guide said cylindrical
parts over the length of the grinding wheel and drive wheel of a
centreless grinder,
[0011] a first guide called the entry guide arranged at one
longitudinal end of the guide chute and adapted to allow the
insertion of cylindrical parts one by one onto the guide chute from
a conveyor system on the entry side of the centreless grinder,
[0012] mechanical means for adjustment of the entry guide relative
to the guide chute,
[0013] a second guide called the exit guide arranged at the other
longitudinal end of the guide chute and adapted to transfer parts
from the chute to a conveyor system on the exit side from the
centreless grinder,
[0014] mechanical means for adjustment of the alignment of the exit
guide relative to the guide chute.
[0015] According to the invention, mechanical means for the
micrometric adjustment of the alignment of the entry guide are
independent from the alignment means of the exit guide.
[0016] In other words according to the invention, means of
adjusting the alignment of the entry and exit guides are provided
that enable a very precise alignment of the guides and the space
between the grinding and drive wheels, to within the nearest
micrometre. Making the two adjustment means independent enables an
even more precise adjustment. This prevents any shifting of the
parts to be ground such as nuclear fuel pellets, still present
between the grinding wheels.
[0017] Thus, the parts (fuel pellets) may be inserted at the entry
to the centreless grinder with no mechanical interference between
them.
[0018] Similarly, there is a continuity in the contact line of the
ground parts and the drive wheel at the exit from the grinder. This
prevents grinding defects related to discontinuity in the contact
as is possible in the state of the art.
[0019] Preferably, the guide chute is a single piece steel part on
which surface and in-core annealing and quenching heat treatments
have been made. These treatments may preferably be completed by
surface treatments once the part (guide chute) has been finished,
to increase some characteristics such as a better coefficient of
friction and greater resistance to wear. This steel is preferably
an XC 38 steel.
[0020] Guide chutes according to the state of the art for a
centreless grinder application for nuclear fuel pellets are
composed of a steel base on which a tungsten carbide plate has been
added that forms the actual guide rail for the pellets, in other
words the part in direct contact with the pellets to be ground.
[0021] The advantage of a tungsten carbide plate is that it has a
very good resistance to wear. The major disadvantage is its
brittleness under shocks and internal stresses in the steel base.
Thus, the disadvantages of guide chutes according to the state of
the art are avoided by making a single-piece steel chute with
in-core and surface heat treatments providing wear resistance
equivalent to tungsten carbide and good resistance to shocks and
the relaxation of internal stresses in the chute.
[0022] According to one advantageous embodiment, at least one of
the two guides is composed of two strips, one of which is fixed and
parallel to the longitudinal edge of the chute placed on the
grinding wheel side and the other is installed on a pivot that
adjusts the space from the fixed guide facing it, the distance from
the pivoting guide being varied by actuation of mechanical means
for adjusting the alignment of said guide. Preferably, the entry
guide and the exit guide are each composed of two strips, one of
which is fixed and parallel to a longitudinal edge of the chute and
the other is free to pivot to adjust the spacing of the guide from
the fixed guide facing it.
[0023] Also preferably, the axis of the pivots of the adjustable
guides is fitted with a polymer bearing. This makes the pivot axis
compatible with the dust and splinters from pellets during
grinding, and consequently eliminates the risk of seizure.
[0024] According to one advantageous variant embodiment:
[0025] the pivot axis of the pivoting strip of the entry guide
and/or the exit guide is (are) mounted in a support,
[0026] the mechanical micrometric means for adjustment of the
alignment of the entry guide relative to the guide chute and/or the
mechanical adjustment means of the exit guide comprise a first
screw screwed into the pivot axis support and a second screw nested
into the first screw with a smaller pitch than the first screw and
adapted to bear in contact with a part of the pivoting strip,
screwing of the first screw into the support causing translation of
the two screws while screwing the second screw into the first screw
and bearing in contact with the part of the pivoting strip causes
pivoting of the pivoting strip.
[0027] The pitch of the second screw is smaller than but
sufficiently close to the pitch of the first screw to create a
micrometric adjustment of the pivoting strips, so as to obtain the
greatest possible precision. The device advantageously comprises a
spring adapted to compensate for functional clearances of the
device by guaranteeing permanent bearing between the second screw
and the pivoting strip.
[0028] Each pivot axis and screw axis support is fixed to the guide
chute, to facilitate assembly.
[0029] Each pivot axis and screw axis support is shaped in a turret
with the two screws nested in each other and arranged in the upper
part of the turret.
[0030] Due to a turret type arrangement, the alignment adjustments
can be made manually by manipulating the screws from the top. This
is perfectly suitable for a glove box environment in which the
centreless grinder is installed.
[0031] The geometric shape and the length of the exit guide are
preferably adapted to limit the number of ground cylindrical parts
buffered at the exit from the wheels. In other words, this avoids
the accumulation of pellets, some of which could collect between
the grinding wheels and be machined beyond the required tolerances.
The inclination of the exit guide and the inclined length cause the
evacuation of the pellets while limiting their kinetic energy
during evacuation to the conveyor on the exit side so that they
remain in the horizontal position on the conveyor.
[0032] If their kinetic energy were not limited, they would be
likely to tip on the conveyor which could damage their final
quality.
[0033] The device preferably forms a single piece assembly to which
adapted handles are fixed to enable its insertion into and
evacuation from a centreless grinder in a glove box. Making it easy
to remove the device manually facilitates maintenance operations on
the centreless grinder.
[0034] The invention also relates to a centreless grinder
comprising a device described above. Such a centreless grinder is
adapted to grinding of nuclear fuel pellets.
[0035] Finally, the invention relates to a glove box in which a
centreless grinder is arranged as above.
BRIEF DESCRIPTION OF THE DRAWINGS
[0036] Other advantages and characteristics will become clear after
reading the detailed description given below with reference to the
following figures among which:
[0037] FIG. 1 is a perspective view of the side of the entry guide
of a device according to the invention in a non-installed
configuration,
[0038] FIG. 2 is another perspective view of a device according to
the invention in a non-installed configuration but on the exit
guide side,
[0039] FIG. 3 is a side view of a device according to the invention
in its configuration installed in a centreless grinder for nuclear
fuel pellets,
[0040] FIGS. 3A and 3B are cross-sectional views on lines A-A and
B-B respectively of the device according to FIG. 3.
DETAILED PRESENTATION OF PARTICULAR EMBODIMENTS
[0041] The terms "lower", "upper", "below", "above", "entry side"
and "exit side" should be considered in the installed configuration
of device 1 according to the invention, in other words with the
guide chute in the horizontal position between the grinding wheel
and the drive wheel of a centreless grinder as shown in FIG. 3.
[0042] The device 1 according to the invention includes firstly a
guide chute 2 adapted to guide pellets over the length of the
grinding wheel 8 and drive wheel (not shown) of a centreless
grinder 10 shown in FIG. 3.
[0043] The guide chute 2 is a single piece part made of XC 38 steel
on which surface and in-core quenching and annealing heat
treatments have been performed. The heat treatments were done to
give the guide chute wear resistance equivalent to tungsten
carbide, good shock resistance and so that the chute 2 has no
internal stresses. This chute 2 comprises an upper part 20, the
function of which is to guide the pellets P of nuclear fuel. As can
be better seen in FIGS. 3A and 3B, the guide part 20 is inclined
and is delimited by two longitudinal edges 200, 201.
[0044] An entry guide 3 is arranged at a longitudinal end of the
guide chute 2: it is adapted to enable pellets P to be slid onto
the chute 2 from a conveyor system not shown on the entry side of
the centreless grinder 10. This entry guide 3 comprises a fixed
strip 30 approximately aligned on the longitudinal edge 200 of the
chute 2 and another strip 31 free to pivot to change the
inclination relative to the other longitudinal edge 201 of the
chute 2.
[0045] The strip 31 is installed free to pivot on an axis 310
fitted with a polymer bearing installed in a support 32 arranged as
a turret.
[0046] The alignment of the pivoting strip 31 is adjusted relative
to the edge 201 of the chute by mechanical means 4. These means are
composed of two screws 40, 41, one nested into the other in the
upper part of the turret 32 (FIG. 3A). The first screw 40 is
screwed into the support 32. The second screw 41 has a smaller
pitch which is similar to the pitch of the screw 40, and the screw
41 is fixed in rotation.
[0047] Rotating the screw 40 causes translation along its axis
relative to the fixed support 32 (screw-nut connection). At the
same time, this rotation of the screw 61 creates a second
translation along its axis relative to the second screw 41. The
difference in pitch results in a small translation of the bearing
point of the screw 41 on the guide 31, which rotates the guide 31.
Such adjusting means 4, 40, 41 make it possible to achieve very
precise adjustment of the alignment of the pivoting strip 31, to
the nearest micrometer.
[0048] A spring 42 compensates for functional clearances of the
device to achieve permanent bearing between the screw 41 and the
strip 31 in the pivoted position.
[0049] Due to the shape and dimensional characteristics of the
entry guide 5 and the alignment adjustments of the pivoting strip
described above, the nuclear fuel pellets P can be inserted with no
mechanical interference between them.
[0050] An exit guide 5 is arranged at the other longitudinal end of
the guide chute 2; it is adapted to enable transfer of pellets P
from the chute 2 to a conveyor system not shown at the exit from
the centreless grinder 10.
[0051] The assembly and arrangement of the entry guide 5 with the
means of adjusting the alignment of the pivoting strip 31 are made
in a similar manner for the exit guide 5, the adjustment means 6,
60, 61 of the pivoting strip 51 of the exit guide 5 being
independent of the adjustment means 4, 40, 41 of the pivoting
strips 31 of the entry guide 3.
[0052] Thus, the exit guide 5 comprises a fixed strip 50
approximately in line with the longitudinal edge 200 of the chute 2
and another strip 51 installed free to pivot to change the
inclination relative to the other longitudinal edge 201 of the
chute 2.
[0053] The strip 51 is installed free to pivot on an axis 510
provided with a polymer bearing installed in a support 52 arranged
as a turret.
[0054] Mechanical means 6 are provided to adjust the alignment of
the pivoting strip 51 relative to the edge 201 of the chute. These
means are composed of two screws 60, 61 nested in each other in the
upper part of the turret 52 (FIG. 3B). The first screw 60 is
screwed into the support 52. The second screw 61 has a smaller
pitch but similar to the pitch of the screw 60 and the screw 61 is
fixed in rotation. Rotation of the screw 60 causes translation
along its axis relative to the fixed support 52 (screw-nut
connection). At the same time, this rotation of the screw 60 causes
a second translation along its axis relative to the second screw
61. The difference in pitch results in a small translation of the
bearing point of the screw 61 on the guide 51 which causes a
rotation of the guide 51. Such adjustment means 6, 60, 61 are
capable of achieving very precise adjustment of the alignment of
the pivoting strip 51 to the nearest micrometer.
[0055] A spring 62 for compensation of functional clearances of the
device is installed between the pivoting strip 51 and the support
52; it can thus provide a permanent bearing between the screw 61
and the strip 51 in the pivoted position.
[0056] As shown, the geometric shape and length of the outlet guide
5 are adapted to limit the number of ground pellets in the buffer
and their exit speed. This prevents said pellets P from tipping on
the conveyor system at the exit from the centreless grinder 10.
[0057] As shown in FIGS. 1 and 2, the device 1 according to the
invention 1 forms a single piece assembly to which pivoting handles
70, 71 are fixed, adapted to enable the insertion into and
withdrawal from a centreless grinder 10. This facilitates
maintenance operations that are difficult in a glove box
environment.
[0058] The assembly 1 is single piece because: [0059] the turrets
32, 52 in which the pivoting strips 31, 51 are installed with
adjustment means 4, 6 and [0060] the supports 72 of handles 70, 71
to which the fixed strips 30, 50 are fixed, are fixed by screwing
to the guide chute which is itself a single piece.
[0061] Although described as a reference to an application in a
centreless grinder in which the functions of the device are
insertion, guidance and evacuation of nuclear fuel pellets in a
centreless grinder, any application that requires insertion,
guidance and evacuation of cylindrical parts with very high
precision to prevent any shift of the parts, could also be
envisaged.
* * * * *