AN APPARATUS FOR AN UNINTERRUPTED CASTING OF CONCRETE INTO BORE HOLES OR THE LIKE FOR THE CONSTRUCTION OF FOUNDATION PILLARS AND FED THROUGH A SYSTEM OF TELESCOPIC PIPES FLUIDE DYNAMICALLY OPERABLE

Abstract: A transportable apparatus comprising a framework (1) supporting by means of hydraulic jacks (7) a pipe telescopic system, to be moved up or down, in its collapsed condition. The telescopic system (3) comprises telescopically con­ nected coaxial pipes (3a, 3b,...) defining in combination, a duct (30) open at its ends for casting concrete, in a bore hole (2). Each of the pipes, the last excepted, is formed by two coaxial walls (15, 15′; 14, 14′,...) and by an upper sidely extending outwards head (28b, 28c,...) forming annular chamber upstream the head (28, 28c,...) and pairs of annular chambers (29a, 29a; 29b′, 29b′;...) downstream of the respective head. Said chambers are open at their opposite end and respectively house the head of the subsequent pipe and at least a variable portion of this latter, means are provided for feeding a pressurized fluid into the chambers (11, 28b, 28c,...) or alternatively in the chambers (29a, 29a; 29b′, 29b′;...), which act together with the heads (28b, 28c,...) as double acting annular cylinders and pistons, for perform­ ing the elongation or collapse of the pipe telescopic system.

Description: AN APPARATUS FOR AN UNINTERRUPTED CASTING OF CONCRETE INTO BORE HOLES OR THE LIKE FOR THE CONSTRUCTION OF FOUNDATION PILLARS AND FED THROUGH A SYSTEM OF TELESCOPIC PIPES FLUIDE DYNAMICALLY OPERABLE The invention concerns a transportable apparatus for the uninterrupted casting of concrete into vertical bore holes or the like, for the construction of foundation piles or pillars or bulkheads made of reinforced concrete, for building purposes, said concrete being fed through a vertical duct, of a variable lenght which is formed by a system of telescopically connected pipes fluid-dynamically operable. It is known that in the building yards, in order to construct foundation piles or pillars of reinforced concrete, first of all vertical holes are drilled in the ground, in which a reinforcement assembly made of iron rods or the like is inserted, afterwards the cement mixture is poured therein until the respective bore hole has been filled up. This procedure is extremely easy and quick, on condition that no ground water be present since when said ground water seeps into said hole in a considerable amount, it can fill up the whole hole drilled in the ground. For the aforementioned purposes the reinforcement cage of iron rods, which is inserted into said bore hole is so shaped so as to define a hollow cylindrical central space of a height equal to the depth of the bore hole or the like, in which pipes of modular lenght, are let down which are every time screwed one to the other so as to define a duct of a height substantially equal to the depth of the bore hole. By way of example, it is stated that a bpre hole can have a diameter of 40 to 180 Cm, while the diameter of the pipes is, in general, of 25 cm; the depth of the bore hole or the like can be from 10 to 60 m, according to the characteristics of the ground. Such a duct, formed by the connection of a plurality of pipes is necessary, since it would be impossible to cast the concrete mixture in the water which is present in the bore hole, because in this case the cement would be taken up by the water and then it could not set, as it is necessary. When the expedient is taken of maintaining the lowermost pipe sligthly spaced apart over the bottom of the bore hole and when the cement mixture is poured through the duct formed by said pipes, the mixture which is being deposited, causes the reascending of the water which raises until the ground surface, from which it is duly removed. As much as the layer of concrete in the space comprised between the outer surfaces of the pipes and the inner surface of the bore hole increases, as much as the length of the duct has to be decreased, by unscrewing one pipe after the other, until the operation will be completed. These last operations have particular importance, since, if the length of the casting duct is not decreased at the right time, -by duly unscrewing the pipes in excess,- there is the risk that the concrete mass could stick in the inside of the duct. This involves the loss of the pipes forming the duct, the loss of the reinforcement cage inserted in the bore hole, the necessity of renouncing to the use of said hole, and what's more, that obliges to drill two other holes on the aides of the abandoned hole, in equally spaced apart aymmetric positions and which substitutes the hole which can no more be used. The just now described inconvenience is recurrent and causes very heavy economical consequences. The removal of one or more sections of the duct, at a not right time, involves also the risk that the reinforcement cage can be raised upwards by the cement mixture. If said inconvenience takes place during the casting, i.e. when the concrete mixer is operative on the place, one incures in higher charges caused by the stopping of the concrete mixer for the time necessary for carrying out the pipe removal. The most serious inconvenience of the present procedure consists in the fact that all the pipes have to be screwed to each other manually and the duct must be lowered everytime into the bore hole, in which the operation is performed, and that an identical manual operation has to be accomplished for the pipe removal therefrom. This involves an enormous waste of time and hand labour, even if, however, the risks of always possible accidents could be left out consideration. The task of the invention is that of providing an apparatus enabling to carry out an uninterrupted casting of a cement mixture into bore holes or pits of circular or rectangular cross section, designed for the construction of foundation piles, pillars or walls of reinforced concrete for buildings or other building constructions, avoiding the aforementioned inconveniences and by employing a labour, which can be reduced to only one workman The invention accomplishes said task by providing an apparatus, transportable from one place to another and which comprises a framework to which a fluid-dynamic operable system of telescopically connected pipes is connected, and which defines a casting duct of a variable length. In the transport or non-use position of the system of telescopic pipes, this latter is raised in the inner space of said framework slightly over the ground level, while during the operation, it is caused to descend into the bore hole until the upper edge of the outermost pipe is positioned at the ground level, while the inner pipes are successively caused to lower, automatically coming out from each other until they come nearly in contact with the bottom of the bore hole, and then these pipes can be withdrawn one after the other, as the cement casting is carried out in their inside, owing to oleodynamic driving system, incorporated in the system of telescopic pipes. As it has been just described, the cement mixture has to be poured in the inside of the feeding duct formed by the plurality of the pipes of the telescopic system, inserted in the bore hole, for the purpose of forcing the water which is present in the hole, to rise on the outside of the duct. The telescopic devices, which are known up to this date, are constituted'of pipes sliding one into the other under the action of pressurized oil or other suitable fluid fed in the inside of a closed axial duct defined in the inside of them. Therefore, this type of known devices cannot be employed for the intended purposes of this invention, since it is necessary that said inner duct defined by the pipes must be an open duct, because it must be used for the feeding of the cement mixture. Provision has been made therefore of a telescopic system of pipes, each having two walls, in the inside of which annular chamber are formed, in said chambers oleodynamic circuits are created for moving the pipe telescopic system, so that the inner space of the axial duct defined in the inside of the telescopically connected pipes is free to receive the casting of the cement mixture. The object of the invention will be described therebelow in more detailed manner, reference being made to an embodiment of the invention given merely by way of an illustrative and not limitating example and shown in the accompanying drawings, in which: Figure 1 is a diagrammatical axial sectional view of the apparatus according to the invention in the rest and/or transfer position thereof; Figure 2 is a view similar to that of Figure 1, but showing the pipe telescopic system in its operative position; and Figure 3 is an axial sectional view of the detail of the telescopic system in an enlarged scale. In Figure 1 the apparatus according to the invention has been shown in its rest and or transfer position. The framework, having a shape substantially similar to a bell of a square plan, is generally indicated at 1. It consists of four support columns 4 having broad resting feet 4a (Pigures 1, 2). Said columns 4 are connected at their upper ends to a truss 5 on which, with the interposition of brackets 7' are securely mounted at least two double acting hydraulic jacks 7 having vertical axis and in the inside of which a piston can reciprocate which is connected to a piston rod 8 (Figures l, 2). Each of said piston rods 8 is hinged at 9 to a radial arm 10, made integral, by welding, for instance, with a collar head 11 fixed on the upper end of the outermost pipe 3a of the pipe telescopic system, generally indicated 3, as a whole. In the Figure 1 the telescopic system is in its raised position and the pipe system is in its collapsed condition, slightly spaced apart over the level of the ground T. The apparatus is transportable and it will be installed just above the bore hole 2, for instance, using a building yard elevator, a crawled truck, a mechanical mule or the like which comprises an oleodynamic transmission by the use of such an elevator or the like the apparatus can be raised by the insertion of the elevator hook through the hooking slot 6 (Figures 1 and 2). Likewise the source of pressurized oil of the same elevator or the like can be used for the feeding of the oleodynamic assemblies which form part of the apparatus and which will be thereinafter described in a more detailed manner. On the contrary, Figure 2 shows the apparatus according to the invention with the telescopic system in working position; in this embodiment the system comprises the pipes 3a, 3b and 3c. The pipes 3a, 3b, 3c define, in combination, an axial casting duct 30 (Figures 1, 2, 3), open on both their ends and having a variable length, owing to the telescopic connection of the component pipes. On the entrance orifice of the outermost pipe 3a (Figure 2), which consists of the collar head 11 a feed hopper 12 is mounted in an amovable manner, by screwing, for instance. With reference to Figure 2 it must be noted that from the outermost pipe 3a the pipe 3b is get out downwards, from the pipe 3b the pipe 3c is get out downwards and that the lower edge of this latter reaches nearly the bottom of the hole 2. Of course, more than three pipes can be provided. That will depend on the chosen modular length of the pipes and on the depth of the bore hole or the like. It must be noted also, that the pipe telescopic system 3 is so arranged that the pipes 3a, 3b, 3c come out from each other according to the decreasing order of their diameters having the annular open orifices of all the working chambers facing downwardly. Such an expedient enables to avoid, as far as possible, that particles of the mixture poured through said pipes can remain adherent to their inner surfaces, thus hampering the operation of the telescopic device. The pipe telescopic system 3, defining, in combination, the casting duct 30, will be described referring in particular to Figure 3. First of all it can be seen that the first pipe 3a, i.e. the outermost one, is stationary and consists of a pair of coaxial walls 14, 14' and that is closed, at its upper end, by the collar 11 acting as a head, and welded to the arms 10 which connect the telescopic assembly to the support framework 1. The second pipe too is formed by two coaxial walls 15, 15', which are interconnected at their upper end by an outwards ligthly extending head 28b, slidably received into the annular chamber 29 (Figures 2 and 3) defined by the walls 14, 14' of said first pipe 3a. Therefore the pipe 3b is always at least partially housed in the chamber 29, forming an oleodynamic cylinder or hydraulic jack having annular working chamber, piston and head 28b. On the side surfaces of the annular head 28b annular grooves are arranged, each housing partially an annular elastic seal element 17 (Figure 3} of the "O-ring" type or the like, so as to permit a seal sliding of the head 28b along the inner surfaces of the two walls 14, 14' of said first pipe 3a. At the inner lower portion of the walls 14, 14' of said first pipe 3a are screwed respectively the annular rings 18 provided with a lower outer flange 18a for abutting against the lower edge of the pipe 3a and which are also provided with annular grooves on the side surfaces facing the walls 15, 15' each groove housing partially an annular elastic element 17. These two rings 18 together with their annular elastic elements 17, form a second guiding means for a seal sliding of the second pipe 3b (Figure 2) along the chamber 29. The rings 18 extend upwards on the side adjacent to the walls 15, 15' with a conical flange 18b, forming a stop means for the downwards stroke of the head 28b. The third pipe 3, which in this embodiment is the last one of the assembly, consists, on the contrary, of a simple wall 16 of a suitable thickness which remains always at least partially inserted in the 29' defined ky the walls 15, 15' of the pipe 3b downstream of the head 28c. The pipe 3c comprises, similarly to the pipe 3b, an annular sidely enlarged head 28c of an outer diameter equal to the inner diameter of the wall 15, and of an inner diameter equal to the outer diameter of the wall 15'. On the lateral surfaces of the head 28c annular grooves are arranged, each of which partially houses an elastic element allowing the seal sliding of the head 28c along the inner surface of each of the two walls 15, 15' of the second pipe, according to a solution similar to the one described with reference to the pipe 3a. Therefore also at the lower end of the inner surfaces of the walls 15, 15' of said second pipe 3b rings 17 are mounted having an outer and respectively inner lower flange 18a and upper conical upwards protecting flange 18b. Each ring 18 has likewise an annular groove to partially house an annular elastic seal element 17. These two rings 18 together with their respective annular elastic elements 17 form second guiding means enabling the seal sliding of the pipe 3c that in this case is the last one of the pipe assembly. In correspondance of the junction zone between the flange 18a and the threaded portion 18c of each ring 18 and annular groove is arranged for receiving a seal ring 17a. Near to the upper head or collar 11 of the pipe 3a in the outer wall 14 of the pipe 3a an orifice 19 is arranged for the admission into or the exit of the pressurized oil from the annular chamber 29 which is formed by the walls 14, 14' upstream of th head 28b, while near to the lower end of the pipe 3a and facing the upwards projecting edge 18b of the ring 18 thereof an orifice 20 for the admission into and the exit of the oil from the outermost annular chamber 29 formed downwards of the head 28k is arranged. The orifices 19 and 20 are connected bs hoses 13' to a source of pressurized oil (Figures 1, 2), said pipes being controlled ky valves (not shown). Said source may be, for instance, the same source installed on the elevator or the like, and which has been used for the transfer of the apparatus. Through the head 28b of the second pipe 3k at least an orifice 21 is arranged for the passage of the pressurized oil from the chamber 29 to the chamber 29k, defined by the walls 15, 15' and the head 28b upstream of the head 28c. A passage 22 beginning from the orifice 22a arranged in the shoulder 15", underneath the head 28b on the side of the wall 15 and which traverse the head 28b in a zone spaced apart from the zone in which passes the vertical orifice 21 and which ends in an orifice 22a' which opens in the innermost chamber 29a, creates a communication between the two annular chambers 29a formed downstream of the head 28b. The passage 22 communicates also with an inner space or longitudinal cavity 23 arranged in the thickness of the wall 15' which opens through an orifice 22a' positioned in its lower part in one of the two annular chambers 29' created by the wall 16 downstream of the head 28c, while the other chamber 29b' is put in communication with the preceding one by at least an orifice 33 arranged in the upper part of the wall 16. The pressurized oil or other suitable fluid fed from the source, installed, for instance, on the building elevator or the like, which has been employed for the transfer of the apparatus, can be fed through one or the other of the hoses 13 to the upper or lower orifice delivery of the hydraulic jacks 7. Likewise the pressurized oil will ke conveyed by means of the hoses 13' in the annular chambers incorporated in the walls of the pipes telescopically inserted of the system 3, (Figure 2) so that as oil will be fed which will passes through the orifices 19 and 21, it will cause the coming out of the pipes 3b and 3c from the pipe 3a, while said pipes are caused to collapse, when the oil is fed through the orifice 20, the passages 22a, 22, 22a', 23, 23a and the orifices 33. In these conditions the pipes 3a, 3b, 3c telescopically mounted can be caused to slide axially one into the other both directions and with a seal connection, letting their inner duct 30 available for the concrete casting. In order to maintain the wall surfaces cleaned out from concrete and muds so as to safeguard the efficiency of the annular elastic seal elements 17 and so as to prevent changes in the seal sliding of the pipes, scraping means 24 (Figure 3) are mounted along the inner lower edges of the rings 18 of the pipe 3a bent towards the respective facing surfaces ES, 15' of the second pipe 3b, as well as along the inner lower edges of the rings 18 of the second pipe 3b, bent towards the facing surfaces of the single wall 16 of the last pipe 3c. At 25 are indicated (Figure 3) means for stopping the upstroke of the head 28b, which are fixedly mounted, underneath the orifice 19, on the inner surfaces of the walls 15, 15t, other means 26 for stopping the upstroke of the head 28c are mounted in the chamber 29b slightly underneath the outlet of the orifice 21. The operation of the apparatus according to the invention takes place as follows. As it has been already said, it is assumed that the same source of pressurized oil of the building elevator, which is employed for the transport of the apparatus is connected to the hoses 13 e 13' provided for the actuation of the jacks 7 of the framework 1, as well as of the oleodynamic system incorporated in the telescopic assembly 3. First of all the elevator provides to raise the apparatus by the use of the hooking slot 6 and the elevator hook and to transfer said apparatus on the use site, duly positioning this latter on the ground just above the hole 2 which has keen previously bored and into which the reinforcement iron framing has been already inserted which will occupy the annular space that will be comprised between the inner surface of the hole 2 and the outer surfaces of the pipe telescopic system 3. During this manoeuvre the telescopic assembly 3 is in its collapsed condition and raised at a level slightly over the level of the ground T (Figure 1). By means of the jacks 7, which could be also substituted by telescopic mechanisms of conventional type, the assembly 3 is caused to lower until the collar head 11 of the first pipe 3a be placed substantially at the level of the ground T. Now (Figure 3) by means of one of the hoses 13' pressurized oil is fed through the orifice 19 of the first pipe 3a, while the other orifice 20 is connected to the recovery tank. A pressure is thus created in the annular chamber 20 upstream of the head 28b of the pipe 3b, so that said pipe 3b (Figures 1, 2, 3) begins to be forced to move downwards, whilst, at the same time the oil passes through the orifices 21 of the head 28b, thus forcing the head 28c together with the third pipe 3c to move downwards until the lower edge thereof reaches a short distance from the bottom of the bore hole 2. The downstroke of the second pipe 3b will be stopped as the shoulders 15" of the head 28b abut against the conical flanges 18b of the lower outer and inner rings 18 fixed to the walls 14, 14' of the pipe 3a, while the third pipe 3c will ke stopped during its downstroke when the shoulders 16' of the head 20c against the conical flanges 18b extending upwards from the lower outer and inner rings 18, fixed to the outer and inner walls 15, 15' of the second pipe 3b. At this point through the feed hopper 12 the casting of the cement mixture can begin; during said casting the pipes 3c, 3b will be automatically retracted one after the other by controlling the respective distributing vales, as the casted mixture will ascend in the annular space comprised between the pipe system 3 formed by the pipes 3a, 3b, 3c and the inner surface of the bore hole 2 or the like. As the oil or other pressurized fluid is fed through the orifice 20, it will fill up the outer chamber 29a and through the passage 22a, 22, 22a' the inner chamber 29a both defined downstream of the head 28b forcing said head 28b to move upwards together with the second pipe 3b until the head 25b abuts against the stop means 25. Through the orifice 22a and the passage 22, the orifice 22a', the inner space 23 and the orifices 23a provided in the wall 15W of the second pipe 3k, the oil passes from the outermost chamber 29a into the innermost chamber 29a, as well as in that 29b' and then into the outermost chamber 29b' passing through the orifices 33, thus forcing the head 28c together with the last pipe 3c to move upwards until the said head 28c abuts against the stopping means 26. When the casting has keen completed, the telescopic assembly, in its collapsed condition, is caused to raise above the level of the ground T by means of the hydraulic jacks 7 so that the elevator or other employed device will ke able to transport the apparatus so as to stop this latter over another bore hole or the like. It is to be noted that all the operations which have keen described and concerning the apparatus as well as the telescopic assembly according to the invention can be carried out by means of the sole workman of the building elevator or other employed transport device. The object of the invention has been described and illustrated with reference to a preferred embodiment. Of course, variants or modifications could ke made concerning the dispositions, dimensions and relative proportions of the parts, without coming out from the field of the invention.

Claims: CLAISS 1. A transportable apparatus for the uninterrupted casting of concrete into a bore hole (2) or the like, for the construction of foundation piles, pillars or walls, made of reinforced concrete or the like, characterized by the fact that it comprises a framework (1) supporting, by means of vertical hydraulic jacks (7), a system (3) of pipes telescopically connected to each other and which are apt to raise and lower said pipe telescopic system (3), which comprises a plurality of coaxial pipes (3a, 3b, ..) which, in combination, define a vertical central hollow casting duct (30) open at its ends and of a length which can vary from a minimum value in which all the pipes are collapsed, each into the other, to a maximum value corresponding to about the depth of the hole (2) and wherein the pipe having the greatest outer diameter is the pipe /3at, the pipes of the telescopic system (3), the last pipe excepted, are each formed by pairs of coaxial walls fl4, 14'; 15, 15', ...) spaced apart from each other and connected to each other by their upper annular heads (11, 28b,28c,...), the heads (28b, 28c,...) extending outwardly from the respective pair of pipes (15, 15'; 16, 16', ...) so as to define respectively an annular chamber (29, 29b, 29c, ...) upstream of the respective head (28b, 28c, ...) and two coaxial annular twin chambers (29a, 29a; 29b', 29b';...), downstream of the respective head, said chambers having a variable volume and slidingly housing the head together with at least a part of the subsequent pipe and being closed at their lower end by a seal and guiding ring (18) fixed to the lower portions of the facing surfaces of the walls of the preceding pipe,and wherein the chambers (29,29b,...), as well as the pairs of chambers (29a, 29b', ...) are respectively interconnected, and wherein in said system of pipes, the first of which is stationary, a pressurized fluid is admitted, so that said the annular chambers (29; 29a, 29a; 29b; 29b', 29b';...), in combination, with the heads (28a, 28k, ...), which respectively act as pistons, form a system of fluid dynamic, double acting, cylinders having annular working chambers and pistons, each incorporated in one of said pipes (3a, 3b, ...) of the telescopic system (3), enabling to obtain the extension or the collapse of said system (3) of the pipes which, in combination, define the concrete casting duct (30), which is provided, at its entrance orifice, with a feed hopper (12) connected to said orifice, in an movable manner. 2. An apparatus according to claim 1, wherein the pipe telescopic system (3) is supported by a framework (1) by means of radial arms (10) made integral with the collar head (11) of the first stationary pipe (3a), said arms being hinged with their outer ends, at (9), to the piston rods (8) of the oleodynamic jacks (7). 3. An apparatus according to claim 1, wherein the framework (1) and the jacks are so dimensioned as ke akle to let raise the pipe telescopic system (3), in its collapsed condition, until a height greater than that of the orifice of the hole fez), and to let lower the same until the head (11) of the pipe (3a) reaches nearly the level of the entrance opening of the hole (2). 4. A telescopic system of pipes to be used in the apparatus according to claim 1 or for other intended purposes, for obtaining an axial duct of a variable length and including an oleodynamic operative system, characterized by the fact, that it is formed, in combination, by a plurality of coaxial pipes (3a, 3b,...) telescopically inserted one into the other, open at its ends, said pipes, the last excepted, being formed by pairs of coaxial cylindrical walls (14, 14'; 15, its';...) of different diameter, each pair of walls being connected at one of their ends by an annular collar or head (11, 28b, 28c, ,.,) so as to define therebetween an annular chamber (29, 29a,...) and wherein the first pipe (3a) having the greatest outer diameter, is stationary, while the subsequent ones are each provided with a collar head (28b, 28c,. ..) forming a peripheral outwards extending flange of such an outer diameter that it can always be housed and seal slide along the walls of the annular chamfer (29, 29a, ...) of the preceding pipe, while the walls of the pipe comprising said head are spaced apart from the respective inner surfaces of said chamber, so as to define, downstream of said head, two annular shoulders if5", 16", ...) and underneath said shoulders two chambers (29a, 29a; 29k, 29b'; ;...) which are closed at the other end ky means of pairs of seal and guiding rings (18), fixed to the lower end of the inner surfaces of the walls facing the inner surfaces of the walls connected to a respective head (28k, 28c, ...) and in the corresponding facing surfaces of the rings (18) annular groove are arranged for partially housing elastic seal rings (17, 17'), while stopping means (25, 26, ...) to limit the upstroke of the respective heads (28b, 28c,...) in the collapsed condition of the pipe system (3) are provided to define the minimum volume of the respective annular chambers are upstream of the respective heads (28k, 28c, ...) which act as pistons, while the stopping means for the downstroke in the elongation direction of the pipe system consist in axially extending conical (18b) flanges of the guiding rings (18). 5. A pipe telescopic system according to claim 4 wherein near one end of the outer wall (14) of the pipe (3a) an orifice (19) is arranged positioned upstream of the stopping means (25) for the upstroke of the head (28k), while near the other end of the same wall (14) a second orifice (20) is arranged, positioned upstream of the ring (18) which seal closes the outer chamber (29a) at this lower end, said orifices (19, 20) being respectively connected to hoses (13') which are, in turn, connected to a source of pressurized oil, with the interposition of control and distribution valves, apt to connect the orifice (19) to the delivery outlet of said source, and the orifice (20) to the oil recovery tank, during the elongation phase of the pipe telescopic system (3), and vice versa, during the collapse stroke of said pipes, wherein through each head (28, 28c, ...) at least an orifice (21) is bored so as to put in communication the annular chambers (29, 29b, ...) placed upstream and downstream of the heads (28b, 28c,...) acting as pistons, while the two annular chambers placed downstream of each heads (28b) 28c,...) are interconnected therebetween by a passage (22a, 22, 22a'), said passage (22, 22a') being also connected to an inner space or longitudinal cavity (23) arranged in the thickness of at least one of the walls of the pipe provided with said head, said cavity extending longitudinally until the other end of said pipe and is provided with an orifice (23a) which opens in the inside of the adjacent chamber of the two chambers of said pipe, while in the other end of the sole wall (16) which forms the last pipe (3n) and which separates the two coaxial chambers, at least one orifice (33) is provided in order to put in communication said chambers to each other. 6. A pipe telescopic system according to claims 4 and 5, wherein at the outer ends of the rings (18), near their inner edges annular scraping means (24) are mounted, bent towards the facing surfaces of the respective walls 15, 15'; 14, 14', ...) of said pipe, which is always partially housed in the annular chamber of the preceding pipe, means which are designed to remove therefrom each particle of any material adherent to said surfaces.

Inventors: GARAVINI, ROBERTO
Applicants: GARAVINI, ROBERTO
Application year: 1985
Main classification: E02D5
IPC codes: E02D5