JPS6141806A - Gripper for inner wall of tubular body - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a gripping device for gripping and removing a tubular body from a tube bundle, and is particularly useful for removing sample heat transfer tubes from the secondary side of a nuclear steam generator.

The operating mechanism of this gripper includes an expandable collet having a plurality of gripping threads that can be inserted into the mouth of the heat exchanger tube to grip the heat exchanger tube and pull it out of the tube bundle of the heat exchange base. Tapered expander members that can be matched are typically used. The tapered expander member is connected to a rod that is slidably inserted into the collet center hole from the collet mouth. When a tensile force is applied to the rod, the taper-shaped expander member is pulled up into the collet mouth. The simulated force applied to the collet mouth by the taper-shaped expander member causes the collet walls to expand outward, causing the collet outer threads to expand. The strips are brought into gripping engagement with the inner wall of the heat transfer tube. Once the heat transfer tube is gripped, a pulling means, such as a hydraulic ram, applies a pulling force across the gripper to zatva.

Pull it out from the tube bundle.

Some of these conventional mechanisms are configured so that the pulling force applied by the hydraulic ram causes the walls of the expandable collet to expand into gripping contact with the tube inner wall as well as to pull the heat transfer tubes from the tube bundle. There is. However, such mechanisms require some sort of collet retention mechanism, such as a hydraulically actuated telescoping sleeve arrangement, to allow the pulling force to pull on the tapered expander member while simultaneously forcing the expandable collet into the mouth of the heat transfer tube. Otherwise, the pulling force by the hydraulic ram would only act to pull the expandable collet out of the mouth of the heat transfer tube rather than expanding the collet into gripping engagement with the inner wall of the tube.

Although these conventional tube grippers work well when the mouth of the heat exchanger tube is in a freely accessible location (such as the tube sheet next to a nuclear steam generator), Find out how difficult it is to use such conventional tube grippers on the steam generator secondary, which are difficult to use in difficult-to-access locations, such as on the secondary of a nuclear steam generator. This will require general considerations regarding the construction and maintenance associated with nuclear steam generators.

In general, a nuclear steam generator includes a primary side that introduces hot, radioactive water from a furnace into, for example, a plurality of U-shaped heat transfer tubes. , including a secondary side in which non-radioactive water is circulated between the heat transfer tubes to generate non-radioactive steam from the energy output of the core; the heat transfer tubes on the secondary side are arranged in a closely spaced tube bundle. . Heat transfer tubes in steam generators transfer heat from radioactive water flowing inside the tubes to non-radioactive water flowing outside. To facilitate this heat transfer, a plurality of horizontally arranged baffle plates and support plates are installed throughout the steam generator secondary to evenly space the heat transfer tubes from each other. Each plate includes a plurality of equally spaced openings (eg, holes) through which the heat exchanger tubes pass, the openings in the plates being aligned with each other such that the legs of the U-shaped heat exchanger tubes are parallel to each other.

After a certain period of use, the heat exchanger tube leg, which is the part of the heat exchanger tube surrounded by the tube sheet that separates the primary side of the steam generator from the secondary side, and the support plate located on the secondary side of the steam generator Corrosive sludge deposits can build up around the pores. To determine the extent to which this sludge deposit is corroding the tube walls in this area, samples of these tubes are periodically cut and removed through the tubesheet from either the primary or secondary side of the generator. When a sample tube to be drawn is removed from the downstream side of the generator through the tube sheet, the mouth of the heat transfer tube is easily accessible since it is at the same level as the side of the tube sheet facing the downstream side of the generator. However, the opening of the sample tube on the secondary side of the generator is not so easy to access.When taking out the sample on the secondary side, first cut off most of the bridge part of the U-shaped heat exchanger tube to be sampled.
The upper ends of the legs of the shaped heat exchanger tube must be opened, and each leg is cut with an inner diameter tube cutter for removal from the tubesheet. Unfortunately, however, the open upper end of the sample tube is closely surrounded by the bridge portions of other U-shaped tubes that are not sampled. When attempting to use a conventional tube gripper to grasp and pull one of these sample tubes, two problems are immediately encountered.

The first problem is that the collet retention mechanism is large, requiring the gripper to be positioned deep between the closely spaced heat exchanger tubes in the tube bundle to properly position the expandable collet within the mouth of the sample tube. It is impossible to confuse. Even if the tube gripper has a cross section small enough to be inserted between these adjacent heat transfer tubes:1. In order to position the gripper and connect it to the hydraulic ram, some kind of stretching mechanism must almost always be used, but in this case correct and reliable operation of the expander is a secondary problem. becomes. As previously mentioned, proper operation of conventional grippers requires a mechanism that applies a tensile force to the tapered expander member to pull it up into engagement with the expanding collet and simultaneously apply a collet retention force. Become. Stretching mechanisms incorporating such collet retention mechanisms (such as the pair of nested sleeves or rod/cylinder mechanisms discussed above) are difficult and costly to machine, and are difficult and complicated to operate.

Further, such a configuration does not provide a stretching mechanism that allows for easy length adjustment (or, in other words, the ability to easily add segments until the desired length is achieved).

Therefore, there is a need for a tube gripper that can be inserted into sample tubes in a dense tube bundle and operated by a simple rod-like stretching means that can be easily adjusted to the required length. In addition, the structure of the gripper itself is simple and reliable, and the sample tube can be quickly grasped and pulled out from the nuclear steam generator, thereby minimizing the time maintenance personnel spend in the radioactive environment of the nuclear steam generator. The present invention broadly relates to a collet assembly having an expandable collet at one end that is insertable into a tubular body and slidably engaged within said collet assembly and engaged with said collet. a gripping means including a collet expander band which is forcibly expanded to bring it into gripping contact with the inner wall of the tubular body; and a rotatable latch for arbitrarily releasing the engagement between the collet and the expander. The present invention provides a device for gripping the inner wall of a tubular body, characterized by comprising:

The preferred embodiment described below is a tube gripper for gripping the inner wall of a heat exchanger tube that can be actuated by a rotary operating latch.

Generally, a tube gripper includes a gripping means that includes a collet assembly and an expander that expands the expandable collet into engagement with the assembly.

and a rotating latch that arbitrarily releases the engagement force between the expander and the collet. When the gripping means is inserted into the upper end of the opening of the substantially vertical heat transfer tube, the weight of the collet assembly supplies the engagement force between the expander and the collet.6 The gripper of the tube of the present invention is also connected to the expander. It also includes a suspension member that is detachably connected to the collet assembly in order to suspend the collet above the expander. A collet engages the expander and expands it into gripping engagement with the inner wall of the heat transfer tube to be extracted.

A relatively simple, gravity-actuated tube gripper with a rotary operating latch for arbitrary actuation allows the gripper to be easily positioned and manipulated within dense tube bundles via a simple extension rod to 1M. The rotary operation latch of the present invention provides a gripper that is particularly useful for gripping and pulling out a sample tube from a tube bundle on the secondary side of a secondary steam generator. The expandable collet of the present invention may include a latch hook having a pin-fitting notch.The expandable collet of the present invention has a mouth portion of the expandable collet at one end and a restraint at the other end that limits the extent to which the expandable collet can be inserted into the mouth portion of the heat transfer tube. They may be constructed as an integral part of a collet assembly, each including a collar.

The gripper of the invention may include an elongated rod that can be easily attached to the suspension member of the gripping means. The elongated rod can be formed of a plurality of removably connectable elongated members having different lengths so that the length thereof can be easily adjusted.

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

1 and 2, in which the same reference numerals indicate the same components, the tube gripper 1 of the present invention includes, as main parts, a gripping means 5 including a collet assembly B, a collet expander 27, and a suspension member. It consists of 35 parts. The suspension heavy member 35 is connected to the collet expander 27 and is detachably connected to the collet assembly 8 via a rotary operation latch 40. The latch 40 includes a latch hook 42 and a latch pin 48. As will be explained in detail later, the gripping means 5 and the suspension member 35
The latch pin 42 provided on the collet assembly 6 can be manually rotated relative to the latch pin 48 provided on the suspension string member 35. In the disengaged state, the weight of the collet assembly 6 causes the frusto-cone 28 to engage the expandable collet 7 and expand said expandable collet 7 when the expander 27 is pulled through the collet assembly 6. Connect thread 17 of collet 7 to tube 3
engage the inner wall of the

In particular, as is clear from diagrams s2 and g4A-4E,
The collet assembly 7 of the gripper 1 includes a collet base 23 forming a distal opening 5 and a proximal stop 25, the expandable collet 7 of the collet assembly 6 having a frustoconical cavity 11 therein. , the tip of this cavity defining said opening 8 of the collet. The cavity 11 has a substantially complementary annular shape to the truncated cone 28 of the collet expander 27. 4B, the proximal end of the frusto-conical cavity 11 follows a cylindrical bore 13 over the entire length of the collet assembly B, with respect to the outside of the collet assembly 8, on the outside of the expandable collet. A plurality of tube gripping threads 17 are formed as shown. As shown in Figure 4D,
A hook-shaped sharp end 18 is formed at the end of each thread 17. When a given retaining pressure is applied, the thread tip 18 of the thread 17 having the hooked profile is more likely to penetrate the inner wall of the tube 3 due to its sharp edges, so it is more effective than the thread having the conventional triangular profile. also effectively engages the inner wall of the tube. This effective initial engagement of the thread tip 18 against the inner wall of the tube 3 is of particular importance in the present invention as an anti-slip measure. This is because a full-scale collet expansion force does not act until a force to pull the tube is applied to the proximal end of the gripper 1.

In a preferred embodiment, the threads 17 are coated with Armoroy™ to increase the hardness to about 70 to facilitate penetration into the Inconel wall of the tube 3. Further, as will be described in detail later, in order to make it easier to remove the expansion collet 7 from the inner wall of the tube 3,
A thread 17 is formed so as to run in a left-handed spiral around the main body of the device.

In order to provide mechanical flexibility, the expandable collet 7 has a plurality of longitudinal slots 1!3a, 1f3 in the wall of the collet 7 so that the gripping action can be carried out effectively.
b, 1f3c, 19d and 19e are formed. As shown in Figure 4C, these slots are preferably evenly spaced around the expandable collet 7, these slots dividing the expandable collet 7 into a plurality of resilient "fingers". Although it is not clear from the drawing, each of the elastic fingers forming the expandable collet 7 tapers slightly inwardly in the non-expanded state, so that the truncated cone 28 of the collet expander 27 forms the truncated end of the collet 7. When drawn into the conical cavity 11, each thread 17 of the gripping means engages with the inner wall of the tube 3 during the gripping movement which becomes almost cylindrical. As is clear from the TJI4A diagram, the longitudinal slot) 1lla.

I8b, 18c,! 8d and 19e form stress relief keyholes 21a, 21b, 21c, 21d and 21e at their respective tips. These keyholes reduce the stresses concentrated at the ends of the longitudinal slots when the frustocone 29 of the collet expander 27 is drawn into the frustocone cavity 11 of the expandable collet, which has a complementary shape. effectively dissipate.

As previously mentioned, the proximal end of the collet assembly 6 includes a collet base 23 and a stop collar 25, and when the operator inserts the gripper 1 from the open end of the tube to the position shown in FIG. In order to prevent the collet from getting caught on the mouth edge of the tube 3, it is preferred that the end of the expandable collet 7 transitions to the front surface of the collet base 23 via an arcuate shoulder as shown. , the collet base 23 has two functions. As a first function, the cylindrical shape of the base 23 keeps the threaded exterior 15 of the expandable collet 7 in a concentric relation to the interior wall of the tube 3 during insertion of the gripping means 5 of the gripper 1 into the opening of the tube 3. position.

)! As a function of 82, the collet base 23 provides the weight of the collet assembly 6 necessary for the frustocone 2S of the collet expander to engage and expand the collet 7 during tube gripping operations. The proximal end of collet assembly 6 terminates in a stop collar 25. The stop collar 25 serves the important function of limiting the extent to which the expandable collar 7 is inserted along the longitudinal axis of the tube 3; the stop collar 25 also
A gripping means 5 is seated at the open end of the tube 3 so that the weight of the collet assembly B is supported by the tube 3 during the gripping operation. Although in the preferred embodiment the stop collar 25 is integrally formed with the collet base 23, other embodiments include the following:
An adjustable stop collar formed by a ring locking screw arrangement may be fitted to the collet base 23; this embodiment limits the extent to which the expandable collet 7 is inserted along the longitudinal axis of the tube 3 prior to the tube gripping operation. Advantageously, it provides a means for longitudinal adjustment.

In addition, if it is desired to make the insertion range into the open end of the tube 3 extremely shallow, a sleeve may be used instead of a ring. In the preferred embodiment, the collet assembly 6 is Vas.
It is made of comax 300 VM tooling and has a sufficiently small diameter to facilitate insertion of the grease 2per 1 into a hole formed in a support plate in a nuclear steam generator. By setting the dimensions in this way, the gripper 1 can grip and pull the sample tube located below the secondary support plate of the steam generator.

The collet expander 27 has a truncated cone 29 at its tip.
and also includes a rod 31 terminating in a threaded end 33 at its proximal end.
1 slidably passes through a cylindrical hole 13 formed at the center of the collet assembly 8. In order for the gripper 1 to operate properly, the rod 31 of the collet expander 27 must be able to slide freely within the hole 13 without getting caught.
7 is also preferably formed with a Vascomax 300 VM tooling network. Although not shown in the drawings, the truncated cone 28
A circular flange may be provided at the tip of the collet to limit the extent to which the truncated cone 29 can be inserted into the truncated conical cavity 11 of the collet and which has a complementary shape. This is desirable if it is desired to limit the amount of radial gripping force that the cone head 29 can exert on the finkers of the expandable collet 7, and also for highly corroded samples where the walls are likely to rupture due to the radial pressure resulting from the gripping force. When pulling the tube, it is necessary to limit the radial gripping force as described above.

Especially the first one. f35 and FIG. 6, the gripper 1 also includes in the preferred embodiment a suspension member 35 which includes a threaded hole 36 for threading the threaded end 33 of the loft 31 of the collet expander 27.
The suspension member 35 includes a pair of parallel flat surfaces 38a, 38b in its central portion, and a slot in the bag 52 shown in FIGS. 3A and 3B for connecting this portion of the gripper 1 to a hydraulic ram. The flat surface can be fitted within 53. Preferably, the suspension top member 35 also includes at its proximal end another threaded hole 37 for receiving the external thread 57 of the extension member 55.

Next, as shown in FIGS. 1, 2, 4A, and 5, the tube gripper 1 of the present invention includes a collet assembly B.
The latch assembly 40 also includes a rotatable latch assembly 40 for removably coupling the collet assembly 1 to the suspension member 35, which latch assembly 40 is preferably integral with the stop collar 25 at the proximal end of the collet assembly 6. The pin includes a latch footer 42 formed therein and a latch pin 48 that can be fitted into a hole 50 provided at the tip of the suspension member 35.
It can be secured with the pin-fitting notch 44 formed in 2. The pin-fitting notch 44 preferably includes a slightly arcuate upper portion 46, so that the weight of the collet assembly 8 is reduced by the collet assembly 6.
The pin 48 is maintained in engagement with the notch 44 while applying a tensile load between the pin 48 and the suspension 35 . However, as soon as this tensile load is removed by, for example, seating the stop collar 25 on the open end of the tube 3, the suspension member 35 can be manually rotated by a small angle in the counterclockwise direction. can be easily removed from the notch 44.

FIG. 7 shows an extension adapter 55 of the gripper 1 of the present invention.
The proximal end is provided with a male threaded portion 57 that can be screwed together. Similar to the suspension member 35, the extension adapter has a 1 in its central portion that can be fitted into the slot 53 of the pack 52.
A pair of parallel flat surfaces $1a, 131b are each provided with a right-handed threaded hole 58 at the proximal end.

The tube gripper 1 also includes stretching means consisting of a single or a plurality of stretching segments 71, an example of which is shown in FIG. Equipped with. Furthermore, each elongated segment 71 has an internal thread 73 of the @1 elongated segment 71 which includes a pair of parallel flat surfaces 77a, 77b which can fit into said slots 53 of the pack 52 for connecting the gripper l to the hydraulic ram. After screwing into the screw hole 58 of the stretching adapter 55, the remaining stretching segments 71 are screwed together in series to form a stretching means of any length. In the preferred embodiment, each stretch segment) 71 is connected to the stretch adapter 55 and the suspension 35, as well as the stretch segment 304.
Constructed from stainless steel. In order to enable the segment 71 to form a stretching means of the required length with a minimum number of threaded joints, it is preferable to form the segment 71 in various lengths from 1 m to 15 cm. To facilitate recovery if dropped,
Eyelet hole 84 with externally threaded portion 87 and ring 68 is screwed into threaded hole 75 of final drawn segment 71 . If gripper 1 is accidentally dropped into the tube bundle, the wire element (first
It is easy to hook it onto the ring 68 of the eyelet hole 65 (shown in the figure) and pull it up.

In operation, as described above, a plurality of stretching segments 71 are sequentially screwed together in series to construct a stretching means of a desired length.

Preferably, a relatively long 1 m stretching segment 71 is first screwed together until the required length of stretching means is obtained.
Next, by completing the stretching means using 15c of stretching segments, the stretching means can be formed with a minimum number of screws.

Next, the male thread 73 of the first elongated segment 71 is screwed into the threaded hole 58 of the elongated adapter 55 . Now, with the collet 7 facing downward, the latch pin 48 is inserted into the pin insertion notch 44 of the rotary latch assembly 40, and the gripper 1 is manually raised upright.

The collet assembly 6 of the gripping means 5 is inserted into the nearly vertical tube 3 until the stop collar 25 of the collet assembly 8 seats around the open end edge of the tube 3. When the gripper operator hits the open end of the tube 3, the operator of the gripper knows that this seating has taken place because of the hard engagement feeling transmitted to the hand from the stretching means. supports the full weight of the Therefore, there is no longer any tensile load between the launch pin 48 connected to the suspension binding member 35 and the arcuate upper portion 46 of the notch 44 of the latch footer 42; By manually rotating the suspension member 35 by a slight angle in the counterclockwise direction, the retainer pin 48 can be easily removed from the pin insertion notch 44.

If the tube 3 is sufficiently loose it can be pulled out by hand, otherwise a hydraulic ram must then be used, in which case the puck 52 is attached to the stretching means of the gripper 1 in order to connect the ram to the gripper 1. A hydraulic ram of conventional construction is coupled to the pack 52. In the preferred embodiment, the plane above the tube bundle! A hydraulic ram is mounted on a table that is slidable along the and y-axes. By providing a slidable table in this way, the operator can easily slide the ram into the correct coupling position with respect to the stretching means after manually inserting the gripper into the open end of the sample tube 3 to be pulled. The ram is then actuated to apply a pulling force to the proximal end of gripper I. Both the flexibility of the walls of the expandable collet 7 and the total weight of the collet assembly
The sharp threads 17 on the outer surface of the collet 7 are set to engage the inner wall of the tube 3 before the tensile force transmitted by the collet expander 27 balances the weight of the collet assembly B. In many cases, the gripping work on the secondary side of a nuclear steam generator is performed under water, so the weight of the collet assembly 8 is reduced despite the weight reduction effect of the buoyancy acting on the collet assembly 8. After the truncated cone 28 of the collet expander 27 has been drawn into the mouth 8 of the collet 7, which must be set to expand, the greater the pulling force that the hydraulic ram exerts on the tube gripper 1, the more , expandable collet sharp thread 1
7 strongly engages with the inner wall of the tube 3. At this point, the tube 3 is pulled out from the secondary side of the steam generator.

In a slightly modified embodiment, the gripper may be constructed so that the stop collar 25 of the collet assembly 6 does not need to be seated around the open end edge of the tube 3 to operate. That is, the upper level 4 of the notch 44 of the latch footer 42
If B is formed in a straight line instead of an arc, the expandable collet is inserted into the open end of the tube 3, and the gripper's stretching means is moved at high speed so that the pin 48 leaves the notch 44 due to the rotational inertia of the collet assembly 8. Gripper 1 just by rotating
can be made to work. When detached, the truncated cone 2
The collet assembly 6 is moved along the rod 31 of the expander 27 under the action of gravity until the collet 8 strongly engages the mouth 8 of the expandable collet 7, causing the collet 7 to expand and engage the inner wall of the tube 3. It slides smoothly.

To release the expandable collet from the inner wall of the tube 3, the operator of the gripper 1 need only remove the stretching means and the stretching adapter 55 and apply a strong compressive force to the suspension member 35 for a short period of time. - detaching the protruding cone 29 from the frusto-conical cavity 11 of the expandable collet 7 and deflecting the elastic fingers of the collet 7 formed by the slots) IEla, 19b, etc., thereby assembling the collet; Release the solid body from the inner wall of the tube 3. Next, push the suspension member 35 toward the open end of the tube 3 and rotate it by a slight angle in the direction of the hour hand to fit the latch pin 48 into the pin insertion notch 44 of the latch footer 42 again. Here, the meaning of giving the spiral 17 a left-handed pitch will be understood.
As the latch assembly 40 is reconnected by rotating the latch assembly 40 in the direction of the hour hand, the thread 17 can move slightly forward along the inner wall of the tube 3 due to its left-handed pitch. The thread 17 is deflected inwardly by this forward movement, and the sharp end 18 of the thread is detached from the inner wall of the tube 3.

[Brief explanation of the drawing]

FIG. 1 is a partial side sectional view showing an embodiment of the tube gripper of the present invention inserted into the open end of a tube. FIG. 2 is a side view of the rotary operation latch of this tube gripper. 3A and 3B are plan and side views, respectively, of a puller pack used to connect the tube gripper of the present invention to a hydraulic ram; FIG. 14A is a side view of the collet assembly of the gripper. FIG. 4B is a cross-sectional view of the expandable collet of the collet assembly shown in FIG. 4A. Figure @40 is a front view of this expandable collet. FIG. 4D is an enlarged sectional view of a sharp thread employed in the expandable collet of the present invention. FIG. 4E is a sectional view of the collet assembly taken along line E-E in FIG. 1. FIGS. 5, 8, and 7 are exploded side views of the tube gripper of the present invention, showing the assembly of the collet expander, suspension member, and stretching adapter of the present invention. FIG. 8 shows sides 1, tube gripper 3, tube 5, gripping means 8, collet assembly 7, fist--collet 27, which can be used in the present invention. ψ・Collet expander 35...Suspension member 40...Rotation operation latch

Claims (1)

[Scope of Claims] 1. A collet assembly having an expandable collet at one end that can be inserted into a tubular body; a gripping means including a collet expander that is brought into gripping contact with the inner wall of the tubular body by expanding the collet, and a rotatable latch for arbitrarily releasing the engagement between the collet and the expander. A device for gripping the inner wall of a tubular body. 2. The apparatus of claim 2, wherein the tubular body is substantially vertical and at least a portion of the force causing said engagement is provided by the weight of the collet assembly. 3. The apparatus of claim 1, wherein said expander is generally conical and slidably engages a central hole of said collet assembly. 4. A suspension member coupled to the expander and detachably coupled to the collet assembly for suspending the collet of the collet assembly above the expander, wherein the latch is connected to the collet assembly. 4. Apparatus according to claim 3, characterized in that the solid body is optionally released from the suspension member. 5. the collet assembly, at an end opposite the expandable collet, limits the depth to which the expandable collet can be inserted into the tubular body; 5. The apparatus of claim 4 including a stop collar for seating said collet assembly of said gripping means at the open end of said tubular body so as to support the weight of the assembly. 6. The present invention further comprises means for operating the latch by rotating the suspension member while the weight of the collet assembly is supported by the open end of the tubular body. Apparatus according to paragraph 6. 7. The latch includes a hook member and a pin member, and the pin member is separated from the hook member by rotating the suspension member while the weight of the collet assembly is supported by the open end of the tubular body. 6. A device according to claim 5, characterized in that it is capable of: 8. The device according to claim 7, wherein the hook member is fixed to the stop collar, and the pin member is fixed to the suspension member. 5. The expander and the collet assembly are configured to slidably engage the expander so that the expander can be slidably inserted into the expandable collet. Equipment described in Section. 10. The apparatus of claim 5, wherein the expander includes a tapered expansion member connected to a suspension member via a rod. 11. The collet assembly includes a hole extending from the mouth of the expandable collet to the other end of the collet assembly, and the rod of the expander passes through the hole. Apparatus according to scope 10. 12. Claim 5, further comprising an extension means for extending the length of the suspension member.
Equipment described in Section. 13. The apparatus of claim 12, wherein said extension means includes a plurality of extension members connectable to each other so as to adjust the length of said extension means. 14. The device of claim 12, wherein said extension means comprises a threaded rod. 15. The device according to claim 13, characterized in that the plurality of extension members can be connected to each other in series via threaded joints. 16. The device of claim 5, wherein the tubular body is substantially vertical. 17. The device according to claim 5, wherein the end of the suspension member is formed as an eyelet. 18. The apparatus of claim 5, wherein the expandable collet includes a plurality of sharp threads for gripping engagement with the inner wall of the tubular body.