FR2990555B1 - MECHANISM FOR GRIPPING A TUBULAR PLATE AND METHOD FOR SUPPORTING SAID MECHANISM - Google Patents

Abstract

Tubular plate anchoring device (30) for suspending a tool from the underside of a heat exchanger tubular plate (30). The device inserts one end of two fingers (70, 72) into corresponding openings in the tubular plate (30) and exerts a lever effect on one finger (70, 72), from the other, to apply a force rubbing against the openings of the tubular plate (30) into which the fingers (70, 72) are inserted to clamp the fingers (70; 72) on the tubular plate (30).

Description

Mechanism for gripping a tubular plate and method for supporting said mechanism

The present invention relates to the field of robotic systems and relates in particular to an improved gripping mechanism for light robotic systems for the maintenance of heat exchanger tubes in a nuclear steam generator.

In a nuclear power system producing pressurized water, the heat produced by the nuclear reaction is absorbed by a primary heat transfer fluid which circulates in the reactor core and is used to produce steam in a heat exchanger called usually steam generator. The steam generator is typically a vertical cylindrical pressure vessel with hemispherical end portions. A transverse plate called tubular plate, located at the lower end of the cylindrical portion, separates the steam generator into a primary side, which is the lower hemispherical section below the tubular plate, and a secondary side lying above the tube plate. A vertical wall divides the primary side into an input section and an output section. The tubular plate is a thick plate of ordinary steel having an array of thousands of holes into which are inserted the ends of U-shaped tubes. One end of each U-shaped tube is inserted into a hole in the tube plate which communicates. with the input section of the primary side, and the other end is inserted into a hole of the tubular plate which communicates with the output section. The primary heat carrier is introduced under pressure into the inlet section of the primary side, flows through the U-shaped tube and exits through the outlet section. The water introduced into the secondary side of the steam generator circulates around the U-shaped tubes and is transformed into steam by the heat released by the primary coolant. Typically, there are thousands of small diameter U-shaped tubes, which provide a large area for heat transfer. The number of tubes in a steam generator is about 4,000 to 15,000. Some steam generators use straight tubes each about 60 feet long. Most steam generators consist of U-shaped tubes or long vertical sections with two 90 ° elbows connected by a shorter horizontal length tube. During the operation of the plant, the high pressure water flowing through the reactor core carries a certain amount of radioactive particles through the steam generators, and some particles settle on the inner surface of the tubes. After the operation of the plant, the steam generators become a source of radiation.

During operation of the steam generator, sometimes degradation occurs in some tubes. This is undesirable because the primary coolant is radioactive and any leakage of the coolant from the reactor to the secondary side of the generator contaminates the steam. However, it is not usually practical to replace the degraded tubes, and instead, the steam generator is periodically inspected and the affected tubes are plugged at both ends. Given the thousands of tubes in the steam generator, the plugging of some tubes does not appreciably affect the efficiency of the heat transfer.

Due to the risk of irradiation present in the steam generators used in a nuclear power plant, the heat exchange tubes of such steam generators must for the most part be remotely maintained in order to avoid exposure of maintenance personnel to potentially dangerous radiation. As a result, a number of robotic systems have been developed to remotely perform repair and maintenance operations on these heat exchange tubes. These robotic systems typically include a kind of robotic distribution arm in combination with any one of a number of specialized tools designed to be carried by the robotic arm, which are known in the art as "end effectors". Some of the common robotic systems for this task use the holes in the tube plate to anchor the robot for example using a number of cam fasteners (typically four or more), as shown in US Patent No. 7,314,343. assigned to the beneficiary of the present invention. Each cam attachment is comprised of a cylindrical arrangement of flexible "fingers" that advance in a single tube and are spaced apart by a central cam actuated to engage the inner surface of the tube. They thus perform the anchoring by the resulting friction force of the fingers on the inner diameter of the tubes. This method of anchoring is effective but poses the problem that cam fasteners are expensive complex devices and can unexpectedly come off if the actuating force is lost.

The present invention aims to provide a simpler gripping tool adapted to anchor a robot on the underside of a tubular plate, without using cam attachment means.

Another object of the invention is to provide a unique mechanism that performs both anchoring and rotary alignment.

Another object of the invention is to provide such a mechanism which produces a very large gripping force through a mechanical advantage.

Another object of the present invention is to provide such a mechanism which automatically locks in place and does not require an actuating force to remain locked.

Another object of the present invention is to provide such a mechanism that can release and tighten again very quickly.

A further object of the present invention is to provide such a mechanism which is self-aligning and provides accurate positioning. The invention relates to a tool comprising an actuator for gripping a tubular plate of a heat exchanger having a plurality of heat exchange tubes extending at least partially through through holes in the tube plate, each of heat exchange tubes having a central axis extending along the length thereof. The actuator includes a first elongated finger sized to have a first end of the first elongated finger at least partially inserted into a first through hole in the tube plate. A second elongated finger is sized to have a first end of the second elongate finger inserted at least partially into a second through hole in the tube plate. The second elongated finger is spaced from the first elongated finger to be substantially aligned with the second one of the through holes when the first elongated finger is substantially aligned with the first through hole. A connecting bar is connected between the first elongated finger and the second elongate finger, at a first height along the first elongated finger and the second elongated finger, which is spaced from the first ends. The connection of the connecting bar between the first elongate finger and the second elongate finger is configured to prevent movement at the first height of the first elongate finger and the elongated second finger in at least one of two lateral directions, ie one towards the other, in opposite directions. The actuator also includes an actuating arm connected between the first elongate finger and the second elongated finger at a second height along the first elongate finger and the second elongated finger, which is spaced from the first height and spaced from the first ends. . The connection of the actuating arm between the first elongate finger and the second elongate finger is configured to move the first elongated finger in at least one of two lateral directions and incline at least one finger among the first elongated finger and the second elongate finger by relative to the axis of a tube or corresponding through hole, into which it is to be inserted, to press a finger of the first elongate finger and the second elongate finger against an inner wall of the tube or hole through and maintain this position until the actuating arm is positively released.

According to one embodiment, the actuating arm tilts both the first elongate finger and the second elongated finger relative to the axis of the tube or the corresponding through hole in which it is intended to be inserted, in order to squeeze the first elongate finger and the second finger elongated against the corresponding tube into which it is inserted. Preferably, the actuating arm switches between a locked position, in which at least one of the first elongated finger and the second elongated finger is inclined relative to the axis of the corresponding through-tube or hole in which it is to be located. inserted, and an unlocked position in which the first elongated finger and the second elongate finger are not pressed against the inner wall of the corresponding tube or through hole. According to another embodiment, both the first elongate finger and the second elongated finger are pressed against the inner wall of the tube or the corresponding through hole when the actuating arm moves in the direction of the number of at least one , among the two lateral directions.

According to yet another embodiment, wherein the first height is between the first ends and the second height, the connecting bar prevents the movement of the first elongated finger and the second elongated finger, one towards the other . In an alternative embodiment, the connecting bar prevents movement of the first elongated finger and the second elongated finger in opposite directions to each other.

According to another embodiment, the second height is between the first ends and the first height, and the connecting bar prevents the movement of the first elongated finger and the second elongate finger, one towards the other. Alternatively, the connecting bar prevents movement of the first elongated finger and the second elongate finger in opposite directions to each other.

According to another embodiment, the first elongate finger and the second elongated finger are configured to move a distance in the vertical direction, independently of the actuating arm. Preferably, the actuating arm comprises a compensator which is configured to accommodate a change in through hole spacing, while maintaining a substantially constant clamping force. The compensator may for example be a pneumatic spring.

In a second aspect, the invention relates to a method of supporting a tool from the underside of a heat exchange tubular plate having a plurality of openings extending through a bottom face. The method includes the step of inserting a portion of a first elongate finger into a first opening in the underside of the tubular plate, and inserting a portion of a second elongate finger into a second opening in the underside of the tube plate. The method exerts a leverage effect on the first elongated finger from the second elongate finger to clamp at least a portion of the portion, either of the first finger or the second finger, which is inserted into the corresponding aperture, against a wall of the opening; and locks the first finger and the second finger in their tight position.

According to one embodiment, the method exerts a leverage effect on both the first finger and the second finger to apply them against the wall of the corresponding opening. Preferably, the lever effect applying step inclines either the first finger, the second finger, or both with respect to an axis of the corresponding aperture into which it is inserted. The method also includes the step of suspending the tool from the first and second fingers. The preceded may also include the step of moving the first finger and the second finger in a vertical direction, independently of a mechanism for performing the levering step. On the other hand, the method may further include the step of compensating for a change in the distance between openings in the underside of the tube plate, while substantially maintaining a constant clamping force. The object of the invention will be better understood by those skilled in the art to the detailed study of the description below of the preferred embodiments, with reference to the accompanying drawings, in which: - Figure 1 is a view in perspective and in partial vertical section of a steam generator, some parts having been removed for clarity; FIG. 2 illustrates a probe support drive assembly disposed in a steam generator reservoir chamber, under a steam generator tube to be inspected, and releasably connected to a remote maintenance arm, for position the drive assembly under the tube to be inspected; FIG. 3 is a cross-sectional view of a portion of a tubular plate, showing the ends of heat exchange tubes that extend therethrough, and an embodiment of the tool of FIG. according to the present invention, for supporting a robot, such as the remote maintenance arm shown in FIG. 2; FIG. 4 is a cross-sectional view of the portion of the tubular plate shown in FIG. a second embodiment of the gripping tool according to the present invention, which is shown when inserted into two of the heat exchange tube ends; FIG. 5 is a cross section of the portion of the tubular plate shown in FIGS. 3 and 4, with a third embodiment of the gripping tool according to the present invention, which is shown when it is arranged in two heat exchange tube ends; FIG. 6 is a cross-sectional view of the portion of the tubular plate shown in FIGS. 3, 4 and 5, with a fourth embodiment of the gripping tool according to the present invention, which is shown when is disposed in two ends of the heat exchange tube; and FIG. 7 is a cross-sectional view of the portion of the tubular plate shown in FIGS. 3, 4, 5 and 6, with a fifth embodiment of the gripping tool according to the present invention, which is shown when disposed in two ends of the heat exchange tube.

Sometimes it is necessary to inspect steam generator tubes for surface and volume defects, using a robot that can position an inspection probe in the tubes to be inspected and can support the equipment used to facilitate the inspection. the displacement of the probe in the tube. The simplified anchoring illustrated in the figures allows a robot type to be supported from the underside of the tube plate.

Referring to Figure 1, a steam generator is generally designated by the reference 10 and comprises a substantially cylindrical outer casing 12, having a cylindrical upper portion 14 and a cylindrical lower portion 16. A moisture separation means 54 for separating a steam-water mixture is disposed in the upper portion 14, so that entrained water is removed from the steam-water mixture. An inner casing 20 is disposed in the lower portion 16. The inner casing 20 is closed at its upper end, with the exception of a plurality of openings in its upper end to allow passage of the steam-water mixture from the inner casing 20 to the moisture separating means 18. The inner casing 20 is open at its lower end and defines an annular space 21 between the inner casing 20 and the lower part 16 of the outer casing 12. A vertical steam generator tube bundle 22 is disposed in the inner shell 20 and has a plurality of U-shaped vertical steam generator tubes 24. A plurality of horizontal circular tube support plates 26 are arranged at different locations. locations along the length of the tube bundle 22, and each has holes for receiving each tube of the bundle of tubes 22, to laterally support the tubes and reduce the vibration caused by the flow in the tubes. An additional support for the tubes in the bundle of tubes 22 is provided in the region of the U-bends of the tube bundle 22, by a plurality of antivibration bars 28.

Still with reference to FIG. 1, a horizontal circular tubular plate 30 is disposed in a lower portion 14 of the outer shell 12, below the first lower support plate 52, and has a plurality of vertical openings 32 which through it, intended to receive the ends of the tube bundle tubes 22, which ends of the tubes extend a predetermined distance through the openings 32. The tube plate 30 is sealingly attached, for example by welding, around the a circumferential edge, to a hemispherical circulation box 34. A vertical semi-circular partition plate 36 is disposed in the circulation box 34, u and is sealed, for example by welding, to the circulation box 34, along the circumferential edge of the partition plate 36. The separating plate 36 is also sealingly attached, for example by welding, to the tube plate 30 along the flat edge of the separating plate 36. The plate 36 separates the circulation box 34 into a reservoir chamber. intake 38 and outlet tank chamber 40.

Referring again to FIG. 1, a first intake manifold 42 and a first outlet manifold 44, which are respectively in fluid communication with the inlet reservoir chamber 38 and the outlet reservoir chamber 40, are disposed on the outer casing 12, below the tubular plate 30. A plurality of manholes 46 are disposed on the outer casing 12, below the tubular plate 30, to allow access to the intake tank chamber 38 and the outlet tank chamber 40. A second intake pipe 48 is disposed on the outer shell 12, above the bundle of tubes 22, and is connected to a water ring. 50 horizontal and substantially toric perforated feed 50 disposed in the upper portion 14 of the outer casing 12 to allow the entry of non-radioactive secondary fluid or feed water into the upper portion 14, through the tubing d 48 and through the perforations (not shown) of the supply water ring 50. A second outlet pipe 54 is disposed on top of the upper portion 14 to let steam out of the steam generator 10 .

During operation of the steam generator 10, the radioactive primary fluid from the reactor, which can reach a temperature of about 620 ° F (327 ° C), enters the intake tank chamber 38 through the first manifold intake 42, and flows through the tube bundle 22 to the outlet tank chamber 40 where the primary fluid leaves the steam generator 10 through the first outlet pipe 44. The secondary fluid, which is water, enters the supply water ring 50 through the second intake manifold 48, which is connected to the feed water ring 50, and flows to the bottom from the perforations (not shown) of the supply water ring 50, in the annular space 21, until the secondary fluid is in fluid communication with the tubular plate 30. Then the secondary fluid leaves the annular space 21 flowing upwards by convection is natural through the bundle of tubes 22, where the secondary fluid boils and vaporizes into a steam-water mixture, following the transfer of heat by conduction of the primary fluid to the secondary fluid, through the walls of the tube bundle 22 which operates as a heat conductor. The steam-water mixture flows upwardly from the tube bundle 22 and is separated by the moisture separation means 18 into saturated water and dry saturated steam which can reach a minimum quality of about 99.75%. The saturated water flows downward from the moisture separating means 18 and mixes with the secondary fluid. Thus, as the secondary fluid enters through the second intake manifold 48, the dry saturated steam leaves the steam generator 10 through the steam outlet manifold 54. In a manner that is well known in the art , the saturated dry steam is finally transported to produce useful work, such as driving turbogenerators for the production of electricity. On the other hand, as mentioned above, in a nuclear reactor, the primary fluid is radioactive and therefore, the steam generator 10 is designed so that the primary fluid is at no point in direct communication with the fluid secondary, to prevent the non-radioactive secondary fluid is contaminated by radioactivity by mixing with the radioactive primary fluid.

It may happen that, due to defects in the walls of the tubes or to cracks in the walls of the tubes, caused by stress and corrosion, certain tubes in the bundle of tubes 22, for example a suspect tube of steam generator ( see Figure 2), develops surface and volume defects and is therefore no longer leakproof. Therefore, it is customary to inspect the tubes of the steam generator, such as tube 56, to detect the location and extent of defects or irregularities, so that corrective action can be taken, preferably before leaks do not develop. A determination as to whether the tube 56 has defects or irregularities sufficient to require corrective measures can be performed by checking the tube 56 with a non-destructive inspection scanning device (not shown). Of course, the scanning device must be appropriately moved, without slipping or creep, on the inner surface of the tube 56, so that the tube can be carefully scanned for defects or irregularities.

As shown in FIG. 2, a probe support drive assembly, generally designated 58, is suitable for moving a probe holder 60 in the tube 56. As described above , a robotic arm 62, supported from two or more of the tubular plate holes 32 with cam fasteners, was used to support the drive assembly 58 during this process. With the present invention a simplified single mechanism allows such a robot to be supported on the underside of the tubular plate which provides a lockable anchorage with rotational stability which would require at least two of the prior art cam fasteners.

A preferred embodiment is shown in FIG. 3. Instead of being engaged with a single tube hole by the cam fastener, as in the prior art, this mechanism is engaged with two tube holes 64 and 66. separated, spaced from one another by one or more steps. When the link mechanism 68 is actuated, it advances the first and second clamping fingers 70 and 72 and engages an inner diameter surface of each tube 64 and 66 (or corresponding hole when the tubes do not fully penetrate the hole). Due to the geometry, the gripping of the fingers will align the mechanism with the two holes 64 and 66, thus establishing a fixed rotation reference, and will produce an anchoring force by friction with the inner diameter surface of the tubes. The rod mechanism 68 provides a significant mechanical advantage that is such that the gripping force is much greater than the actuating force, and with proper sizing and flexibility, the linkage will switch to a locked position, so that the mechanism will remain tight even after the actuating force is removed. As can be seen in FIG. 3, the fingers 70 and 72 have a first end 74 and 76 which are inserted at least partially into the tube plate openings of the heat exchange tubes 64 and 66. The distal ends of the fingers 70 and 72 are prevented from moving laterally outwardly by a connecting bar or rod 78 which extends respectively through an opening 80 and 82 into the distal ends of the fingers 70 and 72 and is retained by an enlarged end or a nut 96 at each end. Preferably, the connecting bar loosely adjusts through the openings 80 and 82, or the connecting rod or rod 78 is flexible, so that the fingers 70 and 72 can tilt (place themselves obliquely). ) against the side walls of the openings in the tubes 64 and 66, when the actuating arm 68 is controlled to come to the horizontal position in which it is locked. The robotic arm 62 which supports the tool (shown in FIG. 2) can be supported by one or the other finger 70, 72 or by the connection bar 78. The actuating arm consists mainly of the two rods 84 and 86 which are connected centrally by a hinge pin 92 and at the ends by articulated supports 88 and 90. There is provided an actuating handle 94 which can be accessed using a remote tool, for example a pole, which is manipulated from outside from one of the manholes.

Figure 4 shows another embodiment in which the actuating rods 84, 86 of the actuating arm 68 are formed as tensioning elements. As explained with respect to FIG. 3, the mechanism automatically aligns with the holes, has a significant mechanical advantage as regards the gripping force and is able to switch to a locked state. Identical references are used to identify corresponding components in the different figures. In this embodiment, the ends of the connecting bars 78 are screwed into openings 80 and 82 in the distal ends of the fingers 70 and 72. The rods 84 and 86 of the actuating arm 68 extend respectively through openings. 98, 100 in the fingers 70 and 72. The distal ends of the rods 84 and 86 are retained by nuts 102, 104 on the other side of the openings 98 and 100. Thus, when the actuating disc 106 is turned in the counterclockwise, the rods 84 and 86 are energized by pulling the fingers 70 and 72 toward each other and pressing the distal ends 74 and 76 against the inner walls of the tube openings 64 and 66. It should be noted that a similar result could be obtained by attaching the distal ends of the rods 84 and 86 directly to the inner surfaces of the fingers 70 and 72, as was the case in the illustrated embodiment. 3 in FIG. 3, and turning the actuating disc clockwise to place the rods 84 and 86 under compression and tilt the ends 74 and 76 of the fingers 70 and 72 outward, against the walls of the openings 64 and 66.

Figures 5 and 6 show other embodiments in which the fulcrum (connecting bar 78) is moved to the upper position and the fingers 70 and 72 are used as levers from the actuating rods 84, 86 , at the lower or distal ends of the fingers, arranged either as compression elements or as tensioning elements. As before, the mechanism automatically aligns with the holes of the tubes, has a significant mechanical advantage for applying the gripping force and is able to switch to the locked state.

It should be noted that different support structures may contain this mechanism and be supported by the tubular plate to perform any number of mechanical tasks, such as inspection of heat exchange tubes, sealing of the ends of the tubes. tubes, rolling the ends of the tubes, welding sections of tubes, and others. In addition, if the finger connections 70, 72 are slit, it is possible to slide the fingers vertically into and out of the tube plate when the mechanism is not actively tightened, which offers a possibility disengaging the tubular plate mechanism, i.e. the connecting bar or the actuating arm or both are loosely connected to the fingers through slots. An example of this arrangement is shown in Figure 7.

Figure 7 shows yet another embodiment of the present invention which has two additional features not provided for in the previous embodiments. The first additional feature provides clearance slots 108 and 110 respectively in the fingers 72 and 70, which allow the fingers to move vertically with respect to the connecting bar 78 or the actuating rods 84 and 86 or both, for enter the tubular plate 30 or leave it. This allows the connecting bar 78 and / or the activation rods 84, 86 to be supported separately as the fingers penetrate the tubes of the tube plate 30, before tightening, or leave the tube plate after Tightening. The second feature includes a pneumatic spring 120 between the primary cam lever 116 and the lock lever 118 to absorb dimensional changes.

As shown in FIG. 7, the two fingers 70 and 72 can be raised to enter the tube plate 30, using the common bar 130, while the connecting bar 78 and the actuating rods 84 and 86 are supported separately, for example by a robot 62. The fingers 70 and 72 can be moved vertically by a neumatic or hydraulic cylinder 136. As the fingers 70 and 72 are raised or lowered, the slots 110 and 108 move respectively on the actuating rods 84 and 86. The rods 84 and 86 are provided with notches 126 which are retained in the slots 110 and 108 by the ends 112 and 114 widened rods 84 and 86, that is to say compared to the notches 126. Similarly, the connecting bar 78 can move in similar slots, although this is not necessary unless the connecting bar 78 and the rods 84 and 86 are supported together, for example Alternatively, the actuating rods 84 and 86 may be provided with apertures in their ends, into which finger notches which move vertically in a similar manner pass. Alternatively, in this latter embodiment, the actuating rods 84 and 86 may be flat bars with through holes in the direction of the peripheral ends of the bars, for the passage of the fingers. In this embodiment, the lower connecting bar 78 is optional, since the common lifting bar 130 for lifting and lowering the fingers can also be used to hold the lower fingers.

The actuating mechanism 68 comprises a cam and a series of actuating rods interconnected. The actuating rods 116 and 118 are connected to the rear plate 148, respectively by pivot couplings 138 and 140, and the cam is connected to the rear plate 148 by a rotatable coupling 142. A pin 132 projects from the surface of the cam and bears against the curved surface of the hook 134 at the lower end of the actuating rod 116, on at least a portion of the stroke of the cam. The actuating rod 116 is connected to one end of the actuating rod 118 via a pneumatic spring 120 which is pivotally connected at its ends respectively to an intermediate segment of the actuating rod 116 and at one end of the actuating rod 118. The actuating rod 84 is pivotally coupled to an intermediate segment of the actuating rod 118, via the fastening tab 124 which is fixed in a manner rigidly to the actuating rod 84. Similarly, the actuating rod 86 is pivotally coupled to an end portion of the actuating rod 118 via the bracket 122 which is rigidly connected to the actuating rod 86.

Once the fingers are in the up position in the appropriate tubes of the tube plate, rotating the cam has the effect of pushing the actuating rod lever 116 to compress the air spring 120 which moves to its position. turn the actuating rod lock lever 118 to tilt the ends 74 and 76 of the fingers 70 and 72 inwardly to engage the side walls of the tubesheet tubes 64 and 66. As the cam 106 continues its clockwise movement, it compresses the air spring 120, thereby producing the locking action. The rotation of the cam 106 continues until it has reached the curved hook 134 on the operating lever 116, at which point the geometry causes a detent (i.e. the cam can not be brought back by the air spring). The use of the air spring 120 allows the locking mechanism to compensate for small dimensional variations in the spacing of the tubes, while producing a nearly constant locking force.

It should be noted that the fingers do not necessarily have a round cross section and that two points of contact provide better automatic alignment with the openings of the tube plate. In addition, the tips of the fingers 70, 72 may be provided with elastomeric sleeves 150 (shown in FIG. 7) to protect the heat exchange tubes.

Claims (23)

A tool comprising an actuator for gripping a tubular plate (30) of a heat exchanger having a plurality of heat exchange tubes (64, 66) extending at least partially through through holes in the tubular plate, each of the heat exchange tubes (64, 66) having a central axis extending along the length thereof, the actuator comprising: a first elongated finger (70) sized to have a first end (74) of the first elongate finger inserted at least partially into a first through-hole in the tubular plate (30); a second elongated finger (72) sized to have a first end (76) of the second elongate finger inserted at least partially into a second through-hole in the tubular plate (30), the second elongated finger being spaced from the first elongate finger to be substantially aligned with the second of the through holes when the first elongated finger is substantially aligned with the first of the through holes; a connecting bar (78) connected between the first elongate finger and the second elongate finger, at a first height along the first elongate finger and the second elongate finger which is spaced from the first ends, connecting the connecting bar between the first elongate finger and the second elongated finger being configured to prevent movement at the first height of the first elongated finger and the second elongate finger, in at least one of two lateral directions, one towards the other, in opposite directions; and an actuating arm (68) connected between the first elongate finger and the second elongated finger at a second height along the first elongated finger and the second elongated finger, which is spaced from the first height and spaced from the first ends, connecting the actuating arm between the first elongate finger and the second elongated finger being configured to move the first elongated finger in at least one of the two lateral directions and incline at least one of the first elongated finger and the second elongate finger by relative to the axis of a tube or corresponding through hole, into which it is to be inserted, to press a finger of the first elongate finger and the second elongate finger against an inner wall of the tube or hole through and maintain this position until the actuating arm is positively released. 2. Tool according to claim 1, characterized in that the actuating arm (68) tilts both the first elongated finger and the second elongate finger relative to the axis of the tube or the corresponding through hole in which it is intended to be inserted, in order to press the first elongate finger and the second elongated finger against the corresponding tube into which it is inserted. 3. Tool according to claim 1, characterized in that the actuating arm (68) switches between a locked position, wherein the finger, at least one of the first elongate finger and the second elongate finger is inclined relative to the axis of the tube or corresponding through hole in which it is intended to be inserted, and an unlocked position in which the first elongated finger and the second elongate finger are not pressed against the inner wall of the tube or the matching through hole. 4. Tool according to claim 1, characterized in that both the first elongated finger and the second elongated finger are pressed against the inner wall of the tube or the corresponding through hole when the actuating arm moves in the direction, to the number at least one of the two lateral directions. 5. Tool according to claim 1, characterized in that the first height is between the first ends and the second height. 6. Tool according to claim 5, characterized in that the connecting bar (78) prevents the movement of the first elongated finger and the second elongated finger, one towards the other. 7. Tool according to claim 1, characterized in that the connecting bar (78) prevents movement of the first elongated finger and the second elongated finger in opposite directions to each other. 8. Tool according to claim 1, characterized in that the second height is between the first ends and the first height. 9. Tool according to claim 8, characterized in that the connecting bar (78) prevents movement of the first elongated finger and the second elongated finger, one towards the other. 10. Tool according to claim 8, characterized in that the connecting bar (78) prevents the movement of the first elongated finger and the second elongated finger in opposite directions to each other. Tool according to claim 1, characterized in that the first elongate finger and the second elongated finger are configured to move a distance in the vertical direction, independently of the actuating arm (68). Tool according to claim 1, characterized in that the actuating arm (68) comprises a compensator which is configured to accommodate a change in the spacing of the through holes, while maintaining a substantially constant clamping force. . 13. Tool according to claim 12, characterized in that the compensator is a pneumatic spring (120). 14. Tool according to claim 1, characterized in that a portion of the first end of the first elongated finger or the second elongate finger or both has a non-circular cross section. 15. Tool according to claim 1, characterized in that it comprises a sheath (150) flexible on a portion of the first end of the first elongated finger or the second elongated finger or both. 16. Tool according to claim 15, characterized in that the sheath is made from an elastomeric material. A method of supporting a tool from a lower face of a heat exchange tubular plate (30) having a plurality of openings extending through said bottom face, comprising the steps of: a portion of a first finger (70) in a first opening in the lower face of the tubular plate (30); inserting a portion of a second finger (72) into a second opening in the underside of the tubular plate (30); applying a lever effect to the first finger, from the second finger, to clamp at least a portion of the portion, either of the first finger or the second finger, which is inserted in the corresponding opening, against a wall of the 'opening; and locking the first finger and the second finger in their tight position. 18. The method of claim 17, characterized in that the lever effect applying step clamps both the first finger and the second finger against the wall of the corresponding opening. 19. The method of claim 17, characterized in that the lever effect applying step inclines either the first finger or the second finger relative to an axis of the corresponding opening in which it is inserted. 20. The method of claim 19, characterized in that the lever effect applying step tilts both the first finger and the second finger relative to the axis of the corresponding opening in which it is inserted. , in order to clamp the first finger and the second finger against the wall of the corresponding opening. 21. The method of claim 17, characterized in that it comprises the step of suspending the tool from the first and second fingers. 22. A method according to claim 17, characterized in that it comprises the step of moving the first finger and the second finger in a vertical direction, independently of a mechanism for performing the effect-applying step. of leverage. 23. The method of claim 17, characterized in that it comprises the step of compensating for a change in a distance between openings in the lower face of the tube plate, while maintaining a substantially constant clamping force.