Abstract:
The disclosure relates to a tool for fitting an inner bearing race carrying a bearing cage and rollers and screws in a turbomachine, comprising two sectored cylindrical casings which respectively cover an upstream end part of the race and the bearing cage, a cylindrical annulus which surrounds the second casing, and a locking ring which is fitted on an upstream part of the first casing and which has means for axially pressing against the annulus and for axially clamping the second casing between the annulus and the heads of the screws carried by the flange.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a tool for mounting an assembly comprising an inner bearing race, a bearing cage and screws for holding in a turbine engine. 
       PRIOR ART 
       [0002]    In the prior art, an assembly of the aforementioned type is mounted on a turbine-engine shaft by means of a dedicated tool. The inner bearing race of a turbine-engine bearing may comprise an upstream end part comprising outer annular wipers of a labyrinth seal, a middle part defining a race for rolling elements (balls, rollers, needles, etc.), in particular rollers, and a cage holding these rollers, and at its downstream end an outer annular flange for fixing to a turbine shaft of the turbine engine, this flange comprising an annular row of orifices for the passage of screws, the heads of which bear on the upstream annular face of the flange. 
         [0003]    The tools of the prior art are not entirely satisfactory, in particular since they do not sufficiently or effectively protect the race, the cage and the bearing rollers, which may therefore be damaged during the use of the tool and the mounting of the race on the turbine-engine shaft, which may result in breakage of the bearing and premature dismantling of the engine. In addition, the tools currently used are relatively heavy, bulky and complex to use, and are not always designed to avoid human errors in faulty use. 
         [0004]    Finally, a tool of the prior art is in general designed to mount a race on a single assembly configuration of the engine and another tool must be used to mount an identical race on another assembly configuration of the engine. It is for example the case of mounting an inner bearing race on a minor engine module, which is generally used in the workshop. The tool for mounting this race cannot be used to mount the same race on a major module of the engine, which represents the actual environment of the turbine engine in maintenance. 
         [0005]    There is therefore a real need for a tool that affords a simple, effective and economical solution to at least some of the aforementioned problems. 
       DISCLOSURE OF THE INVENTION  
       [0006]    The invention proposes a tool for mounting an assembly comprising an inner bearing race, a bearing cage equipped with rollers, and screws for holding in a turbine engine, the race comprising a raceway for the rollers and, at its downstream end, an outer annular flange comprising an orifice for the screws to pass, characterised in that it comprises a first sectored cylindrical envelope that is intended to cover an upstream end part of the race and comprises means for axial holding on the race, a second sectored cylindrical envelope that is intended to cover the cage and the rollers and at least one downstream end part of the first envelope and to come into axial abutment on the screw heads of the flange, a cylindrical ring that is intended to at least partly surround the second envelope and comprises means for downstream axial abutment on this second envelope, and a locking annulus that is mounted on an upstream end part of the first envelope, between the ring and axial retaining means of this first upstream part, and which comprises means for downstream axial abutment on the ring and axial clamping of the second envelope between the bearing means of the ring and the screw heads of the flange. 
         [0007]    The tool according to the invention thus comprises two coaxial envelopes for covering and protecting (against impacts and contaminations for example) the upstream end part of the race, of the cage and of the bearing rollers, respectively, these envelopes being sectored in order to assist mounting/demounting thereof. The first envelope may be held axially on the race by cooperation of shapes and is held radially outwards by the second envelope. The second envelope is held radially outwards by the ring and is immobilised axially on the race while being clamped between the ring and the screw heads. The second envelope thus holds the screw heads in axial abutment on the upstream annular face of the flange of the race, which prevents them from moving during mounting operations (and in particular floating in the orifices of the flange). The second envelope surrounds the rollers of the cage, preferably with a radial clearance, so as to prevent any risk of contact with these rollers. The second envelope may comprise means for radial abutment towards the inside (with respect to the longitudinal axis of the tool and of the race) on the first envelope in order to hold it pressed against the race, and the ring may comprise means for radial abutment towards the inside of the second envelope in order to hold it pressed against the first envelope and the race. This ring is preferably in a single piece. The locking annulus is housed axially towards the upstream end by holding means for the first envelope. It comprises means for axial abutment on the ring and urging of the ring towards the downstream end so that the second envelope, on which the ring bears axially towards the downstream end, is clamped axially between the ring and the screw heads. This locking annulus is also preferably in a single piece. 
         [0008]    The tool according to the invention does not have the drawbacks of the tools of the prior art. It is simple to use and relatively light (a few kilograms) and can easily be manipulated by an operator. It can be used in all types of mounting configuration on the engine, whether it is for example on a minor module or a major module. Finally, the tool according to the invention is not limited to one type of bearing and can be used for several types of inner bearing race. 
         [0009]    Advantageously, the first envelope comprises, at its upstream end, claw teeth intended to engage with complementary claw teeth on the locking annulus so as firstly to allow axial mounting of the annulus on the upstream end part of the envelope and secondly to axially hold the annulus towards the upstream end when the annulus is rotated by a predetermined angle with respect to the first envelope. 
         [0010]    The first envelope preferably comprises at least one resilient annular seal intended to cooperate with the second envelope. This seal in particular limits the relative movements between the first and second envelopes. 
         [0011]    Preferably, the second envelope carries at its downstream end a resilient annular seal intended to come into abutment on the screw heads. This seal in particular makes it possible to compensate for the differences in height of the screw heads carried by the flange, the seal being constrained to a greater or lesser extent according to the heights of the screw heads. 
         [0012]    In the aforementioned case where the inner bearing race comprises, on an upstream end part, outer annular wipers of a labyrinth seal, the tool preferably comprises a protective annulus intended to surround these wipers, this annulus being surrounded by the first envelope and being locked axially on the race by this first envelope. 
         [0013]    The first envelope may comprise an annular groove oriented towards the upstream end for receiving a cylindrical rim oriented towards the downstream end of the second envelope. This rim and this groove form attachment means and cooperate together in order to radially hold the second envelope vis-à-vis the first envelope, before the ring is mounted on the second envelope. 
         [0014]    The ring may comprise, at its upstream end, an internal annular rim intended to be interposed between the upstream end of the second envelope and the locking annulus. 
         [0015]    The locking annulus preferably comprises threaded axial orifices for mounting screws, the free ends of which are intended to bear axially towards the downstream end on the ring, the tightening of the screws urging the ring downstream and causing the clamping of the second envelope between the ring and the screw heads. 
         [0016]    The locking annulus preferably comprises means for gripping the tool, such as two handles diametrically opposed with respect to the longitudinal axis of the tool. 
         [0017]    The tool may comprise a base for supporting the aforementioned assembly (race, cage and bearing rollers and holding screws) and for assembling the various parts of the tool, this base comprising an annular surface that is intended to serve as an abutment for the flange of the race and which comprises orifices for the screws of this flange to pass. The aforementioned assembly is intended to be disposed vertically on the base. 
         [0018]    The present invention also concerns a method for mounting an assembly comprising an inner bearing race, a cage and bearing rollers and screws for holding in a turbine engine, by means of a tool as described above, characterised in that it comprises the steps consisting of: 
         [0019]    c) mounting the first-envelope sectors on the race, 
         [0020]    d) mounting the second-envelope sectors on the race and the first envelope, 
         [0021]    e) engaging the ring on the second envelope, 
         [0022]    f) engaging the locking annulus on the first envelope, for example by an axial translation towards the first envelope and then a rotation by a predetermined angle about the longitudinal axis of the tool, 
         [0023]    g) axially clamping the second envelope between the ring and the screw heads, 
         [0024]    j) engaging the tool and the race on a turbine-engine shaft by axial translation from the upstream end until it comes into axial abutment on an annular surface of this shaft and so that the screws carried by the race flange pass through the orifices in this surface, 
         [0025]    k) screwing nuts onto the free ends of the screws, and 
         [0026]    l) removing the tool. 
         [0027]    The method may comprise one or more of the following additional steps:
       before step c):       
 
         [0029]    a) placing the aforementioned assembly vertically on the supporting base, so that the screws of the flange pass through the orifices in the base, 
         [0030]    b) engaging the protective annulus on the wipers of the race,
       between steps g) and j):       
 
         [0032]    h) heating the aforementioned assembly, either by putting the race and the tool and its base in an oven, or by induction by means of an element that passes axially through the tool and the race and passes through a central orifice in the base, 
         [0033]    i) removing the tool from its base. 
         [0034]    Finally, the present invention relates to a kit for implementing the method as described above, characterised in that it comprises a case for arranging and storing the sectors of the first and second envelopes, the ring, the locking annulus, and optionally the protective annulus, the supporting base and a tool for individual dismantling of the second-envelope sectors. 
     
    
     
       DESCRIPTION OF THE FIGURES 
         [0035]    The invention will be better understood and other details, features and advantages of the invention will emerge from a reading of the following description given by way of non-limitative example and with reference to the accompanying drawings, in which: 
           [0036]      FIG. 1  is a schematic view in exploded perspective of a tool according to the invention for mounting an inner bearing race carrying a bearing-roller cage and holding screws, 
           [0037]      FIGS. 2 to 10  are schematic perspective views of the tool of  FIG. 1  and depicts steps of assembling this tool, 
           [0038]      FIG. 11  is a schematic view in axial cross-section of the tool of  FIG. 1 , 
           [0039]      FIG. 12  is another schematic view in perspective of the tool according to the invention and depicts a variant embodiment of the supporting base, 
           [0040]      FIGS. 13 and 14  are schematic perspective views of the tool of  FIG. 1  and a minor turbine-shaft module of a turbine engine, and depicts steps of mounting the inner bearing race on this module, 
           [0041]      FIG. 15  is a schematic view in axial cross-section of the tool and shaft of  FIGS. 13 and 14 , 
           [0042]      FIGS. 16 to 22  are schematic perspective views of the tool of  FIG. 1  and a major turbine-shaft module of a turbine engine, and depict steps of mounting the inner bearing race on this module and of removing the tool, and 
           [0043]      FIG. 23  is a schematic perspective view of a kit according to the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0044]    Reference is made first of all to  FIG. 1 , which depicts a tool  10  according to the invention for mounting an assembly  12  comprising an inner bearing race  14 , a bearing cage  16  and screws  18 , on a minor or major turbine-engine shaft module, this tool  10  comprising a plurality of parts, the function of which is in particular to protect the race  14  and the bearing cage  16  during mounting and which are assembled on a supporting base  20 . 
         [0045]    In the following description, the terms “upstream” and “downstream” are used with reference to the flow of gases in the turbine engine. In the position of mounting in the turbine engine, the race  14  comprises an upstream end situated towards the upstream end of the turbine engine and a downstream end situated towards the downstream end of the turbine engine. The same terms are used to designate ends of the parts of the tool. In other words, an upstream end of a part of the tool will be situated towards the upstream end of the bearing race  14 , and vice-versa. 
         [0046]    The bearing race  14  has a substantially cylindrical shape with a longitudinal axis A. The expressions “radially inner” and “radially outer” are used hereinafter to designate the radial positions with respect to the axis A. 
         [0047]    The bearing race  14  comprises outer annular wipers  22  on its upstream end part, a raceway on its middle part and an outer annular flange  24  at its downstream end. The wipers  22  are intended to be surrounded by and cooperate with a part of the stator of the turbine engine in order to form a labyrinth seal. The bearing cage  16  is engaged on the raceway of the race  14 , which comprises means for axial holding of this cage in this raceway. The annular flange  24  comprises an annular row of axial orifices for passage of the screws  18 , which are eleven in number in the example depicted. The screws  18  are in general engaged with clearance in these orifices. The assembly  12  formed by the race  14 , the bearing cage  16  and the screws  18  is intended to be mounted on a turbine shaft of the turbine engine, by means of a single tool  10 . 
         [0048]    As will be described hereinafter, the supporting base  20  is designed so as to receive the assembly  12  in the vertical position, that is to say, when the tool is assembled, the longitudinal axis A of the race  14  and of the tool  10  is oriented vertically. This base  20  has a cylindrical shape, its bottom end being intended to be in abutment on a flat surface and its top end comprising an annular groove  26  for receiving the flange  24  of the race  14 . This groove  26  is delimited by two coaxial cylindrical rims that form means for centring the race  14  on the base, the bottom of the groove  26  comprising an annular row of orifices  28  for passage of the screws  18  carried by the race  14 . These orifices  28  are distributed on the bottom of the groove  26  in the same way as the orifices of the flange  24 . They preferably have a diameter slightly greater than that of the screws  18  in order to limit their movement. The base  20  further comprises a central orifice  29  with a square cross-section for passage of means (not shown) for heating the race  14  by induction, these heating means being intended to pass axially through the race  14 , the tool  10  and the base  20 . The supporting base is for example produced from aluminium alloy. 
         [0049]    In the example shown, the tool  10  comprises five annular parts coaxial with each other and with the race  14 , at least some of these parts extending some around the others in the mounting position, as can be seen in  FIG. 11 . The tool  10  comprises a protective annulus  30 , a first sectored envelope  32 , a second sectored envelope  34 , a ring  36  and a locking annulus  38 . 
         [0050]    The protective annulus  30  is intended to surround the upstream end part of the race  14  and to protect the wipers  22  of the race. As can be seen in  FIG. 11 , this annulus  30  comprises, at its upstream (or top) end, an inner annular rim  40  that is intended to come into axial abutment on the upstream end of the race  14 . This annulus  30  is formed in a single piece, for example from aluminium alloy. 
         [0051]    The first envelope  32  has a cylindrical shape overall and is intended to surround the protective annulus  30 . It comprises, at its upstream end, an inner annular rim  42  that extends upstream of the rim  40  of the annulus  30  and provides the axial holding of the annulus  30  on the race  14 . It further comprises, at its upstream end, an annular row of claw teeth  44  that extend radially towards the outside. These teeth  44  are four in number and are regularly distributed around the axis A. They each have an angular extent 45° and are separated from one another by inter-tooth circumferential spaces each having an angular extent of 45° around the axis A. These teeth  44  are visible in  FIG. 1  but not in  FIG. 11  since the cross-section has been produced at the aforementioned inter-tooth spaces. 
         [0052]    The envelope  32  comprises at its downstream end an inner annular rim  46  that is intended to be housed in an annular outer groove with a complementary shape in the race  14 , this groove being situated directly upstream of the bearing cage  16 . The first envelope  32  therefore extends axially over the end part of the race  14  situated upstream of the bearing cage. As can be seen in  FIG. 11 , the envelope  32  has a diameter close to that of the bearing cage  16 . 
         [0053]    The envelope  32  further comprises at its downstream end a cylindrical rim  48  oriented upstream and which forms a channel or annular groove for receiving and attaching a cylindrical rim  50  oriented towards the downstream end of the second envelope  34 . The first envelope  32  further comprises on its outer surface an annular groove for receiving a resilient seal  52  that is intended to cooperate with an inner surface of the second envelope  34 . This seal  52  can be mounted captive in the groove of the envelope  32 . 
         [0054]    The envelope  32  is sectored and formed by sectors intended to be disposed circumferentially end to end. In the example depicted, the envelope  32  comprises two sectors, each sector comprising a complete claw tooth  44  and two half-teeth  44  situated at the circumferential ends of the sector. Each sector further comprises one half of the aforementioned seal  52 . 
         [0055]    The second envelope  34  has a cylindrical shape overall and is intended to surround in particular the bearing cage  16  and the downstream end part of the first envelope  32 . The envelope  34  surrounds the bearing cage  16  with a radial clearance (for example around 1.5 mm) in order to prevent any contact between the bearings and inner surface of the envelope  34 . 
         [0056]    The envelope  34  comprises at its downstream (or bottom) end an outer annular rim  54  that extends upstream of the heads of the screws  18  and comprises, on its downstream annular face, an annular groove for receiving a resilient seal  56  intended to bear axially on the heads of the screws  18 . This seal  56  can be mounted captive in the groove of the envelope  34 . The envelope  34  can bear radially towards the inside on one or more annular surfaces of the race  14 . The envelope  34  comprises at its upstream end an outer annular rim  58  for axial abutment of the ring  36 . 
         [0057]    The envelope  34  is sectored and formed by sectors intended to be disposed circumferentially end to end. In the example depicted, the envelope  34  comprises five sectors, each sector comprising a sector of the aforementioned seal  56 . 
         [0058]    The envelopes  32  and  34  are for example produced from steel. 
         [0059]    The ring  36  has a cylindrical shape overall and is intended to surround the upstream end part of the second envelope  34 . It comprises at its upstream (or top) end a radial protrusion formed by respectively inner and outer annular rims, the inner rim  60  extending upstream of the rim  58  of the second envelope  34  and being intended to come into axial abutment on this rim  58 . 
         [0060]    The ring  36  is formed of a single piece, for example made from steel. 
         [0061]    The locking annulus  38  comprises an annular row of claw teeth  62  that extend radially inwards. These teeth  62  are four in number and are regularly distributed around the axis A. They each have an annular extent of 45° and are separated from one another by inter-tooth circumferential spaces each having an angular extent of 45° around the axis A. These teeth  62  are visible in  FIG. 1  but not in  FIG. 11  since the cross-section has been made at the aforementioned inter-tooth spaces. The teeth  44  and  62  of the envelope  32  and of the locking annulus  38  are intended to cooperate with each other for the mounting of the annulus  38  on the envelope  32  by claw coupling. 
         [0062]    The annulus  38  is intended to be mounted on the upstream end part of the envelope  32  and to be interposed axially between the claw teeth  44  of the envelope  32 , situated upstream, and the upstream end of the ring  36 , situated downstream. 
         [0063]    The annulus  38  comprises an annular row of threaded through orifices for screwing screws  64  from the upstream end, the free ends of these screws  64  being intended to bear axially on the upstream end of the ring  36  in order to urge it downstream and thus to clamp the second envelope  34  between the ring and the heads of the screws  18 . 
         [0064]    The annulus  38  further comprises handles  66  for gripping and manipulating the tool  10 , these handles here being two in number, connected to the upstream end of the annulus and diametrically opposite with respect to the axis A. 
         [0065]    The assembly of the tool  10  on the bearing race  14  will now be described with reference to  FIGS. 2 to 10 . 
         [0066]    A first step of the assembly method consists of placing the aforementioned assembly  12  (race  14 , cage and bearing rollers  16  and screw  18 ) on the supporting base  20 . For this purpose, the assembly  12  is positioned coaxially above the base  20  disposed horizontally, so that the screws  18  carried by the flange are aligned with the orifices  28  in the base  20  ( FIG. 2 ). The assembly  12  is then moved in translation along the axis A towards the base  20  until the screws  18  pass into the orifices  28  in the base and the flange  24  engages in the groove  26  in the base and bears on its bottom. 
         [0067]    The protective annulus  30  is then engaged on the wipers of the race  14  ( FIG. 3 ) by translation of the ring downwards, until its rim  40  bears on the upstream or top end of the race. 
         [0068]    The sectors of the first envelope  32  are next mounted one after the other on the protective annulus  30  and the race  14  ( FIGS. 4 and 5 ). For this purpose, each sector is positioned radially outside the annulus  30  and is moved in radial translation towards the annulus until its rim  46  (not visible in  FIGS. 4 and 5 ) engages in the corresponding groove in the race  14 . The envelope  32  holds the annulus  30  axially on the race by means of its rim  42 , and is itself held axially on the race by cooperation of its rim  46  with the race  14 . 
         [0069]    The sectors of the second envelope  34  are next mounted one after the other on the first envelope  32  and the race  14  ( FIGS. 6 to 7 ). For this purpose, each envelope sector  34  is disposed radially outside the first envelope  32  so that the rim  50  of the envelope  34  is situated upstream of the rim  48  of the envelope  32 . The envelope  34  is then moved in radial translation inwards until it comes into radial abutment on the envelope  32  and is then moved in axial translation downstream so that its rim  50  engages in the groove defined by the rim  48  of the envelope  32 . The lengths or axial dimensions of the rims  48 ,  50  are designed so that they do not prevent the axial abutment of the seal  56  of the envelope  34  on the screw heads  18 . More precisely, the length of the rim  50  of the envelope  34  is less than the depth or axial dimension of the groove defined by the rim  48  of the envelope  32  so that on mounting an axial clearance remains between the free end of the rim and the bottom of the groove. Likewise, the length of the rim  48  and the envelope  32  is less than the depth or axial dimension of the groove defined by the rim  50  of the envelope  34  so that on mounting an axial clearance remains between the free end of this rim and the bottom of this groove. These clearances enable the envelope  34  to be clamped between the ring  36  and the screw heads  18 . Because of the manufacturing tolerances, the upstream or top surfaces of the screw heads  18  are not all necessarily coplanar. The tool  10  makes it possible to overcome this drawback by means of the seal  56 , which is intended to come into abutment on the screw heads and to compensate for the differences in axial positions of these heads, the seal being compressed to a greater or lesser extent according to these axial positions, which vary over a few tenths of a millimetre for example (IT=0.4 mm). 
         [0070]    The ring  36  is next engaged on the second envelope  34  by axial translation downwards ( FIG. 8 ), until its rim  60  bears axially on the rim  58  of the second envelope  34 . 
         [0071]    The locking annulus  38  is next mounted by claw coupling on the upstream end part of the first envelope  32  ( FIGS. 9 and 10 ). For this purpose, the annulus  38  is positioned coaxially above the first envelope  32  so that its claw teeth  62  are aligned axially with the inter-tooth spaces of the envelope  32  ( FIG. 9 ). The annulus  38  is next moved by axial translation downwards until it comes into abutment on the upstream end of the ring  36 . The teeth  62  of the annulus  38  are then situated downstream of the teeth  44  of the envelope  32 . The annulus is next rotated about the axis A by an angle of 45° so that the teeth  44 ,  62  are aligned axially ( FIG. 10 ). The annulus  38  is then held axially upwards by the teeth  44  of the envelope  32 , which extend upstream of the teeth  62  of the annulus. 
         [0072]    The screws  64  are screwed, preferably manually, so that their free ends bear on the ring  36  and urge it downstream. This will cause the annulus  38  to be put in axial abutment on the claw teeth  44  of the envelope  32  and moreover cause the envelope  34  to be clamped axially between the ring  36  and the screw heads  18 , which will be prevented from moving when the tool is manipulated. 
         [0073]    The tool  10  makes it possible to distribute the reverse forces of the pressing of the screws  18  in the groove of the race that receives the rim  46  of the first envelope, without any risk of hammering or scratching the surfaces of the groove and of the bearing cage. 
         [0074]    Before it is mounted on a turbine-engine shaft, the assembly  12  may be heated. The base  20  shown in  FIGS. 1 to 11  comprises a central orifice for induction heating means to pass, as described above. In the variant embodiment in  FIG. 12 , this same base  20  (but turned over) is used to heat the assembly  12 , this base being intended to be introduced into an oven with the assembly  12  and the tool  10 . This base  20  has the overall form of a cylindrical bowl, the base of the bowl being intended to be in abutment on a flat surface and the top periphery of the bowl comprising a cylindrical surface  72  for abutment of the flange  24  of the race  14 . 
         [0075]      FIGS. 13 to 15  are now referred to, which depict steps of mounting the assembly  12  on a minor module  80  of a turbine shaft of a turbine engine. This minor module  80  can be used in particular in a workshop. It comprises a cylindrical part  82  that is connected substantially at its middle to a substantially frustoconical part  84  comprising an annular surface  86  oriented upstream and on which the upstream ends of axial orifices  88  for mounting the screws  18  of the assembly  12  emerge. 
         [0076]    A first step depicted in  FIG. 13  consists of coaxially positioning the tool  10  upstream of the module (which is in general placed so that its longitudinal axis is oriented horizontally, so that the screws  18  are aligned axially with the orifices  88  in the module  80 . The tool  10  is next moved by axial translation towards the module until the screws  18  engage in the orifices  88  in the module and the flange  24  of the race bears on the annular surface  86  of the module ( FIGS. 14 and 15 ). Nuts are then screwed onto the threaded rods of the screws  18  and are tightened against the module. The tool  10  can then be disassembled, as will be described in more detail hereinafter. 
         [0077]      FIGS. 16 to 18  depict steps of mounting the assembly  12  on a major module  90  of a turbine shaft of a turbine engine, this major module  80  representing the actual environment of the turbine engine under repair conditions. The major module  80  comprises a minor module as described above, at the upstream end of which annular parts  92  are fixed. These parts  92  comprise in particular inner annular wipers (not visible) that must be protected during the operation of mounting the assembly  12  on the module  90 . For this purpose, a removable annular protective member  94  is engaged in the parts  92 , this member covering the aforementioned wipers but not interfering with the mounting of the assembly  12  on the module  90 . 
         [0078]    The steps of mounting the assembly  12  on the major module  90  by means of the tool  10  ( FIGS. 17 and 18 ) are the same as those described above with reference to  FIGS. 13 to 15 , 
         [0079]      FIGS. 19 to 22  show steps of disassembling or demounting the tool. 
         [0080]    In  FIG. 19 , the screws  64  of the locking annulus  38  have been unscrewed and the annulus has been rotated by 45° about the axis A, so as to be able to remove it from the envelope  32  by axial translation upstream. The ring  36  is next removed by axial translation upstream ( FIG. 20 ) and the sectors of the second envelope  34  are removed one after the other. The sectors of the first envelope  32  are removed one after the other ( FIG. 21 ) and then the protective annulus  30  is removed by axial translation upstream. The protective member  94  is then removed by axial translation upstream ( FIG. 22 ). At least some of the steps of removing the parts of the tool  10  and of the member  94  can be performed by means of another tool such as pliers. 
         [0081]      FIG. 23  shows a kit  100  for implementing the aforementioned steps. This kit  100  comprises a case  102  for arranging and storing the various parts of the tool  10  described above. The case  102  comprises a box  104  and a lid  106  closing the box, the box comprising a foam block  108  comprising hollowed-out parts forming chambers for housing the various parts of the tool. The block  108  defines a chamber for housing the supporting base  20 , a housing chamber for each sector of the second envelope  34 , a housing chamber for each sector of the first envelope, a chamber housing the ring, a chamber housing the protective annulus  30 , a chamber housing the locking annulus  38  and a chamber  110  housing pliers (not shown) for disassembling the tool  10 .