EP0716195A1 - Mechanical connection for concrete reinforcing rods, device for installing this mechanical connection and process for fixing mechanical connections for concrete reinforcing rods - Google Patents

Abstract

A mechanical connection for concrete reinforcing rods lacking a threaded end or the like comprises - a sleeve (11) with a cylindrical hollow body into which is introduced axially the end of the reinforcing rod (7) which has no connecting element; - a coaxial threaded portion (8) on the end of the sleeve (11); - the outer material of the sleeve (11) having undergone deformation by necking-in in the area of the end of the reinforcing rod so that - the material of the ribs (10) on the reinforcing rod also deforms in order connect the reinforcing rod and the sleeve. This deformation may be produced by a piston (21) and die (23) of a jack screwed on to thread (8). After removal of the jack, the further reinforcing rod is attached via thread (8). <IMAGE>

Description

The invention relates to a mechanical connection of concrete rods. It relates to a mechanical connection of concrete rods, a socket with a hollow body, as well as a device for the establishment of this mechanical connection. The invention also relates to a method for fixing a mechanical connection of concrete rods.

It will find its application in particular in the field of construction of buildings using concrete such as buildings in a city or port or road works.

In these fields of application, it is known to use mechanical connections to link the concrete rods in order to ensure the continuous transmission of a tensile force.

The mechanical connection according to the invention can be used on construction sites in order to link parts that have been the subject of industrial preparation in the workshop with other concrete reinforcing bars available on the construction site.

These rounds that are used on the site can have a straight end or be in the shape of a butt and the round has in known manner on its outer surface ribs or ribs whose dimensions are quite irregular but which are naturally proportioned relative to the diameter of the circle. All these elements are calculated to give the connection a certain resistance and depending on the structure used, it will be possible to have rounds of large diameter with large ribs or of small diameter with smaller ribs.

These ribs are generally arranged on the external surface of the circle, for example according to a helicoid whose pitch will also depend on the diameter of the circle used and the resistance sought.

In certain circumstances, it will sometimes be necessary to link concrete rods embedded in a mass of old building concrete with new concrete rods, to carry out a work extension or a modification.

Thus, in many cases, concrete reinforcing bars arrangement on the existing structure has not been provided by construction with a mechanical connection such as a thread to facilitate the connection or, on the contrary, has a thread damaged by corrosion or sea water.

Thus, in many cases, the ends of bars embedded in the concrete to be bonded do not have, by construction, a sufficient mechanical connection. The ends of unprepared concrete rods are free and free of threads and it is therefore not easy to connect two concrete rods end to end.

Sometimes the absence of thread on the end of a bar rather than being due to the construction of the bar is due to an impossibility of using this thread because it is corroded.

The absence of threading could also have as its origin an accident on site, for example if such a previously threaded bar had been sawed inadvertently.

Any mechanical preparation of the end of the bars requires intervention in a specialized workshop on the bar. This operation creates a break in the reinforcement production chain and involves considerable handling. This load break is very expensive and often involves the transport of hundreds of tonnes of steel, from the place of mechanical preparation to the place of shaping and / or assembly.

The object of the present invention is to integrate the assembly operation of the sleeve into the manufacturing circuit without having the obligation to prepare the end of the bar before assembling the reinforcements.

It may also be that on a site, a series of vertical bars must be linked with a concrete slab such as a floor produced industrially in the workshop and which would present a series of horizontal bars at the outlet of the concrete. These bars can be rectilinear or crossed but it is their end that must be connected on the site with vertical concrete rods which will constitute the vertical concrete element.

There is also sometimes on site high concentration of steel when the floor bars and the vertical bars are very close together and it is sometimes difficult to be able to access it easily with large tools.

It is known today to bond such bars by means of a tubular sleeve which is crimped to the press. For this, it is necessary to use bulky outer jaws since the system which implements an enveloping jaw by external pressure must be powerful. This size is a drawback when the concentration of steel and reinforcing bars is high because, if the two bars are too close together, it is no longer possible to intervene quickly on site.

The pressing elements and the tool environment are heavy and bulky, this is why there must be sufficient space between the axes of the concrete rods to be able to crimp them and in practice, fifteen centimeters of spacing are required.

The operator's daily output on the site is very modest and it takes four to eight connections per hour for heavy equipment, for example of the order of one hundred and sixty kilograms.

It should also be noted that, when the jaws intervened by external pressure to crimp the two bars end to end, it is not possible to check and test if the operation is correctly carried out and it is then necessary to trust the 'operator.

The devices and dies used are very heavy to allow a reaction of the force on the tool. The large force used on the matrix means that a heavy and bulky outer frame must be used because the force must be transmitted to the frame. We use pressures up to two hundred tonnes and it is not easy to intervene quickly and efficiently with total security on all crimps.

The known devices which crimp perpendicularly to the rounds in successive passes act in a random manner because they do not know exactly how the round will be stressed in a hollow or in a rib. It is therefore necessary to use sleeves of considerable length, of the order of 200 to 250 millimeters, and it cannot be guaranteed that all the crimps will be carried out in good conditions. The result of the crimping depends on the pressure used by the operator.

Known devices employing perpendicular crimping with a movable jaw and a fixed die also lead to an almost compulsory misalignment of the two rounds to be bonded because the two bars are no longer aligned taking into account the asymmetry and the irregularity of the rounds which are used.

The object of the present invention is to provide a mechanical connection of concrete rods, which overcomes the aforementioned drawbacks and which allows a concrete rod to be bonded, the end of which has no connection means such as a thread. This absence of threading can be due to corrosion or simply to the fact that no mechanical connection was planned during construction. It is also possible that this mechanical connection was inadvertently cut on site.

Another object of the mechanical connection of concrete reinforcing bars according to the invention is to be able to operate quickly on the site and therefore with light and handy tools.

Another object of the mechanical connection of concrete reinforcing bars according to the invention is to be able, precisely because of the small size of the tool, to operate on concrete irons in high concentration, that is to say very close together. each other.

Another object of the mechanical connection of concrete reinforcing bars according to the invention is to be able to be tested by applying thereto after bonding a stress, for example equal to 90% of the elastic limit.

Another object of the device for the establishment of a mechanical connection according to the invention is to allow the production of tested connections so that all the connections produced will be completely safe in terms of the quality of the crimping of the socket on the end of the round.

Another advantage of the mechanical round connection to concrete according to the invention, by controlling the quality of the crimping, is therefore to be able to greatly reduce the length of the sleeve itself and of course to achieve a cost price of the mechanical connections in a very small work since the amount of metal used will be greatly reduced.

Another object of the present invention is to be able to intervene quickly on the site to bond an element which has been industrially manufactured with concrete rods protruding with other concrete rods usable on the site.

We can for example prepare all the horizontal slabs at the same time industrially and then bond them with vertical bars which will all be adjusted to the same height for example by means of a preliminary coppicing of the ends of the bars.

Another advantage of the device according to the invention is to be very handy and easily usable on site.

The device is provided with a possibility of testing the work which has just been carried out to have the proof that the connection is functional, which will naturally be very advantageous since before, it was not possible to have, using crimping with jaws, quality control of the manufactured link.

Another object of the device according to the invention is to be able to greatly increase the quantities of links processed which may increase to four hundred per day instead of forty today. The device can be installed at a fixed station to industrialize the preparation of bars.

• une douille avec un corps creux cylindrique dans lequel est introduite l'extrémité du rond qui est dépourvue d'élément de connexion,
• un filetage à l'extrémité de la douille,
• le corps creux et le filetage étant coaxiaux afin de pouvoir liaisonner deux ronds placés bout à bout,
• la matière externe de la douille ayant subi une déformation par formage d'empreintes linéaires ou hélicoïdales,
• la matière des côtes du rond pénètre dans le corps creux de la douille,

afin de liaisonner le rond et la douille.According to the present invention, the mechanical connection of concrete rods, which will find its application in particular in the field of construction of concrete elements on site, intended to come to fit on a straight end or butt, the round having ribs on its external surface, is characterized by the fact that it comprises:

• a socket with a cylindrical hollow body into which the end of the round which is devoid of element is introduced connection,
• a thread at the end of the socket,
• the hollow body and the thread being coaxial so as to be able to link two rounds placed end to end,
• the external material of the sleeve having undergone deformation by forming linear or helical impressions,
• the material of the ribs of the round enters the hollow body of the sleeve,

in order to link the round and the socket.

• un corps de vérin à double effet,
• un tube prolongateur taraudé ou fileté s'adaptant sur le filetage de l'extrémité de la douille et fixé au corps du vérin,
• un piston creux du vérin se déplaçant entre le corps et le prolongateur,
• un outil à billes ou à grains disposé à l'extrémité du piston susceptible de se déplacer verticalement et/ou en rotation pour déformer la matière externe de la douille et forcer les côtes du rond à béton à pénétrer à l'intérieur de la douille, afin de provoquer la liaison et sertir la douille sur l'extrémité du rond.

The device for implementing the mechanical connection on a concrete ring, the end of which is devoid of connection element, intended to link two rounds end to end, is characterized in that it comprises:

• a double-acting cylinder body,
• a threaded or threaded extension tube fitting onto the thread of the end of the bushing and fixed to the cylinder body,
• a hollow piston of the jack moving between the body and the extension,
• a ball or grain tool placed at the end of the piston capable of moving vertically and / or in rotation to deform the external material of the bush and force the ribs of the concrete rod to penetrate inside the bush, to cause the connection and crimp the sleeve on the end of the round.

• recouvrir l'extrémité d'un rond à béton sans élément de connexion au moyen d'une douille,
• provoquer l'écrasement de la douille sur l'extrémité du rond par déplacement vertical et/ou circulaire d'un outil,
• choisir une matière pour la douille plus malléable que la matière du rond afin de provoquer la pénétration des côtes du rond à l'intérieur du corps creux de la douille,
• renvoyer sur le rond les efforts induits par l'outil.

The method of fixing a mechanical connection of concrete rods, in particular usable on site, implementing the connection according to the invention, is characterized in that it consists in:

• cover the end of a concrete rod without connection element by means of a socket,
• cause the sleeve to be crushed on the end of the round by vertical and / or circular movement of a tool,
• choose a material for the socket more malleable than the material of the round in order to cause the penetration of the ribs of the round inside the hollow body of the socket,
• return the forces induced by the tool to the circle.

The present invention will be better understood on reading of the following description, which is given for information only and which is not intended to limit it. It is accompanied by the accompanying drawings which form an integral part thereof.

Figure 1 shows the mechanical connection of concrete rods according to the invention implemented on a vertical bar and a horizontal bar in stock.

Figure 2 is a view of the device according to the invention actuating the mechanical connection of a concrete ring on a round whose end is devoid of connection element.

Figure 3 is a sectional view of the sleeve showing the shape obtained after deformation.

Figure 4 shows a variant of the tool which, instead of having offset grains as shown in Figure 2, will be ball.

Reference is made to FIG. 1 which shows a mechanical connection of a concrete reinforcing iron, generally designated by (1). This concrete reinforcing rod known to those skilled in the art is widely used today on construction sites to reinforce constructions. We will try to link the concrete ring (2) with another round (3) which will be arranged coaxially and end to end with the round (2). The connection (1) thus ensures a transmission of the tensile force in a continuous manner between the circle (2) and the circle (3).

There is shown in Figure 1 a single round (3) but it could for example be part of a horizontal floor (4) but which would include a multitude of rounds arranged substantially parallel. Each round (3) can come out of the floor (4) in a straight line or on the contrary have a butt-shaped end (5) as shown in FIG. 1.

We can also use the mechanical connection of concrete reinforcing bars according to the invention in other devices suitable for certain buildings with male / male or female / female sleeves.

The structure also includes a vertical part into which a series of circles (2) arranged in parallel will be integrated. It is therefore necessary to connect the end (6) of the round (3) with the end (7) of the round (2). It should be noted that this end (7) of the concrete round is devoid of connection element, that is to say that it does not include any threading or tapping because then it would be easy for the skilled person d '' operate a mechanical connection.

We have seen that the absence of threads could come from construction or be due to corrosion or an unfortunate sawing on the site.

The mechanical connection (1) according to the invention, when it has been secured to the end (7) of the round by the method according to the invention, can be connected to the round (3) for example by screwing. The system used will be of the union type (3 pieces), no bar that can be turned.

Reference is made to FIG. 2 which shows the concrete rod (2) with its end (7) devoid of any connection element and in particular of thread. This concrete rod of appropriate diameter has on its outer surface ribs (10) arranged for example in a circular or helical fashion. These ribs may be irregular but in known manner facilitate the maintenance of the circles in the concrete when subjected to significant pulls. These ribs have different width and height dimensions and are adapted according to the diameter of the circle.

Taking into account the construction method, the diameter of the round is not very regular and these ribs are not very precisely distributed on the external surface of the round.

The mechanical connection of concrete reinforcing bars according to the invention comprises a socket (11) with a cylindrical hollow body into which the end of the round (7) is introduced through the orifice (12).

In one embodiment, the sleeve (11) has a cylindrical shape over a large part of its height but it still has a chamfered part (13), the end of the sleeve (11) has beyond the chamfer ( 13) a thread (8) also shown in FIG. 1.

The mechanical connections of concrete reinforcing bars are therefore constituted by the cylindrical sleeve (11) which adapts to the non-threaded end (7) of the round (2) and which includes a thread (8). It should be noted that the round (2) and the thread (8) are arranged coaxially along the axis (14) in order to be able to make an end-to-end connection of the rounds (2 and 3).

It should be noted that the circles must be very well aligned and coaxial because if the edges are no longer aligned, it may result in offset forces creating a moment prejudicial to the traction of the circles and to the tests of "permanent elongation" or test of slip.

According to the invention, by axial crimping imposed by the threaded rod and the tapping of the crimping sleeve as well as by the annular shape of the tool, the method according to the invention leads in a more certain way to center the two bars which whatever the geometry of the concrete rod.

The various elements of the mechanical connection are naturally made of metal but it is advantageously possible to choose for the sleeve (11) a material which is more malleable than the material constituting the concrete reinforcing rod (2) and this in order to cause the penetration of the ribs ( 10) inside the socket (11) when a pressure is exerted on the external surface of this socket. This penetration can be achieved for example at the end (7) of the round by causing the bushing to be crushed on the end of the round. This can be obtained for example by vertical and / or circular displacement of a tool generally designated by (15).

The material of the ribs of the concrete rod penetrates into the internal zone of the sleeve facing the circle in order to bond the circle and the sleeve.

There is shown in Figure 2 the device (15) for the establishment of the mechanical connection (1).

This device is provided with a threaded extension tube (16) comprising at one of its ends a thread (17) and a thread (30) which is screwed onto the thread (8) of the connection (1).

The thread (17) of the extension is fixed in the end (18) of the body of the hollow cylinder preferably used double-acting. The body (19) of this jack defines with the extension (16) an area (20) in which is likely to move a hollow piston (21). A tool (23) which may be of different suitable shapes and for example circular, with offset grains, or with balls, has been secured to the end (22) of this piston. These devices can, in certain cases, be adjustable according to the diameter of the round to be bonded. We can adjust the crimp by playing on the number of balls and possibly creating a circular movement to achieve a crimp in a helical pattern.

To improve surface contacts and obtain a better bond, it is advantageous to use a heating system allowing a temperature rise from 500 to 750 ° C for five to ten seconds. A high-frequency self-induction system is satisfactory for providing localized heating of small rooms. We can obtain rapid heating and a rise in temperature in a few seconds with small, low-frequency light equipment.

The cooling of the metal after bonding has an important advantage because the thermal stress of the shrinking accentuates the crimping and thus causes very good adhesion and complete and total solidarity of the round and the sleeve.

Heating, in particular by self induction, gives much reduced crimping forces and allows the use of lesser tools.

It should therefore be noted that, for a round diameter of 40, sixty tonnes of pressure are required with four balls and that for a round diameter of 40, fifteen tonnes of hot pressure are required for a circular tool (23).

It is by having thus mastered the connection by securing the round and the coupler in complete safety, it will then be possible to greatly reduce the length of the coupler with respect to the couplers used for example with crimping perpendicular to the bars.

FIG. 4 shows the detail of this tool (23) equipped with balls. Balls produce deformations (27) on the external part of the sleeve (11). A longitudinal and / or circular crimping is caused during the vertical descent of the tool with a grip on the outer surface of the sleeve, which causes controlled penetration and possible adjustment by means of the balls. This adjustment is for example obtained by means of the screws shown diagrammatically in (28).

The ball crimping can be helical if an inclined and semi-peripheral groove is practiced on the outside of the crown of the tool, a fixed point forcing rotation during the pushing, the tool being fixed on a ball thrust, the angle of the groove being fixed as a function of the pitch (s) of the propeller and in relation to the spacing of the bolts of the concrete rod.

The goal is to considerably increase the length of the footprint and to penetrate well into the hollow spaces of the concrete rod, while recreating on the mechanical parts the adhesion function of the concrete rod.

The external material of the sleeve undergoes deformation by forming linear or helical impressions.

When the piston descends in the direction of arrow F, the end of the tool (23) moves vertically by a distance D. The base (24) of the tool (23) comes into contact with a swivel element (25). This element is itself placed on a swivel plate (26) with an interposed neoprene washer.

The tool (23) is applied first on the plane (13) then on the whole of the external periphery of the sleeve (11) by a high pressure communicated by the piston. It is this pressure and the simultaneous deformation of the periphery of the bush, as shown in FIG. 3, which cause the end (7) of the concrete rod to bond with the bush. The tool makes streaks (27) on the external part of the sleeve in sufficient numbers, preferably regularly distributed over the entire periphery. The number of streaks will naturally depend on the diameter of the round to be bonded.

The tool during its vertical and / or circular displacement over the distance D will dig grooves on the outer periphery of the sleeve and by pressure, will also cause penetration of the ribs (10) of the concrete ring at its end (7). This penetration will naturally be made possible by the choice of the material constituting the sleeve (11) which will be more malleable than the material of the round in (7).

We can thus link the socket with the end of the concrete ring and crimp them. The material of the ribs of the round at its end (7) will be housed in the internal part of the sleeve to cause this connection.

Referring to Figure 2, we see that the device (15) is operated by the piston (21) when sending the oil under pressure. The sleeve (1) which forms a body with the extension (16) is fixed to the body of the jack (8). A reaction takes place on the hollow piston which descends over distance D and causes crimping. The drawings (10) on the outer surface of the round penetrate the material in the inner area of the sleeve which is more malleable.

At the end of the operation, the face (24) of the tool comes to bear on the swivel element and we test at the preset value for example 99% of the elastic limit of the concrete reinforcing bar. This test will be considered good if, during the traction exerted, no slip is observed recorded by a drop in the oil pressure read on the cylinder pressure gauge.

If the crimping was not carried out in good conditions of application, the connection will be detached during the test, and it is better that it is at this time there to avoid subsequent inconvenience on the site. It will either have to be redone or replaced.

We see that the device for the establishment of the mechanical connection which has been described is very compact and that it acts vertically on the circle. It can therefore be easily used in areas where space is reduced or where there is a large concentration of concrete reinforcing bars.

It should be noted that the forces induced by the tool (23) are returned to the sleeve (1) and the round (3). We use the reaction of the part. The force induced by the jack is returned by the part. This effort contained in the room is not dispersed and it is not necessary to have a frame press release to amortize it. The force dispersed by the jack is returned and fully taken up by the part. It is the inertia of the parts which totally tolerates the force of the jack, something which was not possible with the previous devices because the part did not play this role of reaction during crimping. The sleeve and the end of the round play a functional role of reaction during the operation and one can work in the air without important tools or support.

The value of the distance D over which the crimping will be carried out will naturally depend on the density of the ribs and the protuberances on the circle as well as on the diameter of the circle and on the operating mode, cold, hot, longitudinal or helical.

The present invention may also be applied to products other than concrete rods and for example smooth crimp bars, the end being previously "scratched" by mechanical means or by compression of an imprint.

For the final test, there is the ball joint support device in the event of bars protruding from the concrete, for the test on free bars the locking system on the bar is with self-tightening jaws of the type of traction.

Claims (8)

Mechanical connection of concrete rods, which will find its application in particular in the field of construction of concrete elements on site, intended to come to fit on a straight end or butt, the circle having ribs on its external surface, characterized by the fact that it includes: - a socket (11) with a cylindrical hollow body into which is introduced the end of the round which is devoid of connection element, - a thread (8) at the end of the bush (11), - the hollow body and the thread being coaxial in order to be able to link two rounds placed end to end, - the external material of the sleeve having undergone deformation by forming linear or helical impressions, - the material of the ribs (10) of the round penetrating into the hollow body of the sleeve (11), in order to link the round and the socket. Mechanical connection of concrete reinforcing bars, in particular usable on construction sites, according to claim 1, characterized in that chamfers (13) are produced on the external surface of the bush (11) between the thread and the cylindrical part of the sleeve. Device for the implementation of the mechanical connection on a concrete ring whose end is devoid of connection element, intended to link two rounds end to end, is characterized in that it comprises: - a double-acting cylinder body (19), - a threaded or threaded extension tube (16) adapting to the thread of the end of the socket and fixed to the body of the jack, - a hollow piston (21) of the jack moving between the body (19) and the extension (16), - a ball or grain tool (23) disposed at the end of the piston capable of moving vertically and / or in rotation to deform the external material of the sleeve (11) and force the ribs (10) of the concrete ring to penetrate to inside the socket, to cause the connection and crimp the socket on the end of the round. Device for setting up a mechanical connection according to claim 3, characterized in that it comprises a swivel element (25) on which the periphery of the tool abuts in the end of descent phase of the jack , to test the bond. Method for fixing a mechanical connection of concrete rods, in particular usable on site, implementing the connection according to claim 1, characterized in that it consists in: - cover the end of a concrete ring without connection element by means of a socket, - provoke the crushing of the sleeve on the end of the round by vertical and / or circular displacement of a tool, - choose a material for the socket more malleable than the material of the round in order to cause the penetration of the ribs of the round inside the hollow body of the socket, - return the forces induced by the tool to the circle. Method for fixing a mechanical connection of concrete reinforcing bars, in particular usable on a building site, according to claim 5, characterized in that once the connection has been made, for example, the elastic limit of the concrete concrete. Method for fixing a mechanical connection of concrete bars, according to claim 5, characterized in that to improve the contact surfaces and obtain a better bond, the end of the circle is heated to a temperature of 500 to 750 ° C for five to ten seconds and cooled to cause the assembly to shrink and accentuate the crimping. Device for setting up a mechanical connection according to claim 3, characterized in that the heating is carried out by means of a high frequency self-induction.

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