EP1160027A1 - Expansion plier - Google Patents

Abstract

The shaping pliers for connecting copper tubes has a cap with a plastic plug (4), an axial stop (3) and a shaft (5) extending through the plug to actuate the stop for movement towards the plug. A linkage exerts a traction force on the shaft opposite to a hole formed in a washer (11) surrounding the shaft. The linkage has a handle with a cavity receiving the washer and a piston sliding in the cavity. The piston is moved by a lever hinged on the handle.

Description

The invention relates to the connection of tubes, and more specifically, the devices for making sockets on plastically deformable tubes.

A socket designates the connection of two tubes of diameters substantially equivalents by fitting one tube into the other or by fitting tubes and an intermediate piece. A female socket designates a slight increase in the inside diameter of a tube over a given length, which can be produced by plastic deformation. When forming an socket, it is usual to achieve a female socket by plastic deformation carried out on a tube or on the intermediate piece. In the following, the term socket is used to designate a female socket produced by plastic deformation.

The assembly by socket applies in particular to the assembled copper tubes by welding or soldering, or to synthetic tubes connected by inserts.

It is notably known to connect two copper tubes annealed by soldering or by brazing by making a socket beforehand on one of the two tubes. We thus forms a socket on one of the sides of the connection. This socket presents an inner diameter slightly greater than the nominal diameter of the tube, on a length of about once this nominal diameter. After formation of the socket and pickling of the parts to be welded, the smooth end of the other tube is introduced at the bottom of the socket, the connection is then made by hot capillary action, by welding or solder.

It is also known to carry out sockets on tubes based on materials semi-rigid synthetic materials (polyethylene, crosslinked polyethylene, polybutene, polypropylene ...) but also on multi-layer tubes, and in particular tubes with metallic core, which are connected by mechanical fittings. One of the types of fitting used is the compression fitting by ring sliding. Such fitting consists of the fitting body with a part of a grooved insert to be inserted inside the tube, the tube, and a ring that slides outside the tube. During the slip of the ring in superposition of the insert, the part of the captive tube between insert and ring are in compression and the tube / fitting assembly becomes non-removable and resistant. The fitting of the fitting therefore requires a slight increase the inside diameter of the tube in order to introduce the fluted insert without difficulty. This increase in diameter is obtained by plastic deformation. To avoid bead formation (which is unsightly and increases the effort of mounting) when installing the ring, this increase in diameter must be precise in diameter but especially in length.

The JR company markets a pliers with tilting by two metal sectors. This shouldered tool, of the J.R pliers type, consists of two articulated handles and a mouthpiece. The tip consists of two stacks of half-cylinders of different diameters, which are articulated at the level of a generator of their peripheral surface. We make the socket by introducing the tip into the tube to be deformed, then by applying successive pressures on the handles. We do thus rotate the half-cylinders between them and these thus deform the tube to form a socket. This clamp can be used for different diameters but it is mainly intended for forming casings on copper tube annealed before fitting and brazing. The instructions for use with the annealed copper tube recommend a progressive action with rotation of the nozzle in the tube. For tubes made of material synthesis, to obtain certain socket characteristics corresponding to the need, such as the length or the inside diameter of the socket, or the regularity of the forming, it is necessary to take certain precautions: it is necessary in particular to give expansion shots while turning but on the other hand avoid sinking the jaws over their entire length.

The SAPER company also markets multi-sector socket pliers. The tip is cylindrical, made up of several metal sectors deviating under the action of a cone. A set of sectors is reserved for only one tube diameter to be deformed. Switching to a different diameter tube requires thus the change of the complete nozzle. This tool is more precise than the previous, with a higher cost in return.

These solutions have drawbacks. Due to the geometry of sectors, plastic deformation is heterogeneous and it can result in embrittlement or bleaching of the tube. This has the consequences of causing montages defective, create unsightly bulges and cause breaks in clamps: thus, during the formation of a bead, any excessive effort causes the breakage of the advance ratchet of the mounting clamp. Precision interlocking requires a more complex and therefore more expensive tip. In addition, handling of the clamp proves to be delicate, in particular requiring rotation of the nozzle in the tube.

The document GB-639 103 describes a socket training device. This device consists of a matrix, a tip and an actuation key the mouthpiece. The matrix is formed by two articulated parts defining the profile final exterior of a tube. The articulated parts also define a stop for the end of the tube and a stop for the actuation key. The activation key is consisting of a cylindrical sleeve with an internal thread and a bar passing through the sleeve and arranged perpendicular to the sleeve. Buffer comprises a threaded cylindrical rod integral with a piston. A tampon is placed against the piston and surrounds an unthreaded part of the rod. Key rotation causes compression of the buffer between the piston and the tube stop. Buffer thus widens radially.

The document JP09193250 describes a process for forming an enclosure. The end of a polyethylene tube is heated. We use a tool with a elastomer pad crossed by a rod. This rod ends with a stop in contact with the tampon. Another stop is brought into contact with the pad. A cylinder pulls on the rod. The pad is thus compressed between the stops and widens radially.

The document FR-A-2 380 831 describes a tool for forming an socket comprising an expandable mandrel fitting into the tube. This chuck is consisting of several segments linked together elastically. These segments form a conical axial passage for the passage of a conical needle. The pull of the needle causes the radial expansion of the mandrel.

Document EP-A-0 397 570 describes an apparatus for forming sockets. this device has a fixed handle with movable jaws, a chuck conical end and a movable handle articulated on the mandrel by a pivot. The movable handle is also connected by a link, offset from the axis of the mandrel, with movable handle.

No clamp of the state of the art solves all of these problems.

There is therefore a need for an interlocking pliers resolving one or more of these disadvantages.

The invention proposes a solution to these various problems; she offers a pliers fitted with a nozzle making it possible to obtain both uniform deformation of the tube and high deformation precision, both in length and in diameter. The invention allows simplified handling during the production of the socket. The invention also improves the service life of the pliers and of the tips. The invention also allows to obtain a conical socket bottom.

More specifically, the invention relates to an interlocking clamp comprising an end piece with an elastomeric pad, an axial stop, a through shaft said pad, the shaft driving the stop in translation towards the pad when it is stressed, a thrust washer pierced with a hole through which the shaft passes, means for traction of the shaft, opposite the hole, the traction means having a body with a handle and a through cavity formed in the body, said washer stop substantially closing one end of the cavity, a piston sliding in said cavity, in which are provided means for coupling the shaft, a lever mobile mounted for rotation on the handle and one end of which biases the piston.

Alternatively, the end of the lever is separable from the piston.

According to another variant, the lever is rotatably mounted on the handle by at least one link.

According to yet another variant, the tampon is of substantially cylindrical shape.

According to yet another variant, the stop comprises a circular face of diameter substantially equal to the diameter of the tampon.

It can also be provided that the stop is metallic.

Alternatively, the pad comprises several elastomeric washers.

According to another variant, metal washers are interposed between elastomeric washers.

According to another variant, each tampon has a hardness of between 50 and 110 Shore A.

• figure 1, une vue schématique en coupe d'une pince à emboíture, d'un embout et d'un tube , avant formation d'une emboíture selon l'invention;
• figure 2, une vue schématique en coupe d'une pince à emboíture, d'un embout et d'un tube , durant la formation d'une emboíture selon l'invention;
• figure 3, une vue schématique en coupe partielle d'une pince à emboíture et d'un embout selon l'invention.

Other characteristics and advantages of the invention will appear on reading the following description of embodiments of the invention, given by way of example and with reference to the appended drawings, which show:

• Figure 1, a schematic sectional view of a socket pliers, a tip and a tube, before forming a socket according to the invention;
• Figure 2, a schematic sectional view of a socket pliers, a tip and a tube, during the formation of a socket according to the invention;
• Figure 3, a schematic partial sectional view of a locking pliers and a tip according to the invention.

The invention proposes to achieve a socket in a tube, to compress axially inside the tube and between two stops an elastomeric pad, for cause its radial widening. The radial deformation of the tampon causes the formation of the socket when the pad comes into contact with the wall of the tube in which it is inserted. The invention also provides a device facilitating compression buffer between the two axial stops.

The invention thus makes it possible to achieve a localized increase in diameter of a tube, uniform and of high precision, with a simple handling tool and long life. Tests have shown that the tip is held better than 50,000 operations. The tool body has withstood over 250,000 operations without failure.

The example which follows details an embodiment of a nozzle according to the invention. Figure 1 is a schematic sectional view of a socket pliers, a end piece and a tube, before forming a socket according to the invention. The figure shows in section a tube 1, at the end of which is inserted a nozzle 2. This tip includes a stop 3, a shaft 5 and an elastomeric pad 4. Also shown in the figure, a clamp 6 coupled to the endpiece, which is described in detail below.

An elastomeric pad here designates a pad which is both incompressible, but deformable. The fact that the tampon is incompressible ensures that it deforms radially when it is axially stressed in compression by the stop and by the clamp, as explained below; preferably, the variation in volume of the buffer, when is subjected to a pressure of 50 MPa, is less than 5%. This value ensures that the deformation of the tampon effectively causes deformation of the tube in which the tip is inserted. The fact that the pad is deformable ensures that it deforms radially when it is compressed, and when it exerts a pressure substantially constant over the entire inner surface of the tube with which it is in contact. This pressure can reach 30 Mpa, even 40 Mpa and depends on the force exerted on the handles. The stamp comprises two faces, substantially perpendicular to the axis of the end piece and parallel: the first face is in contact with the stop 3, the second face is a free face. In the example, it has a substantially cylindrical shape, which corresponds to the inner straight section of the tube.

The stop 3 is disposed against one face of the pad 4, and extends substantially on the entire face of the tampon. Its function is to transmit an axial force of compression on the tampon. The shaft 5 crosses the buffer and is connected to the stop 3 of so as to allow it to transmit to the buffer 4 a force exerted on the shaft. can transmit an axial force on the stop 3. In the embodiment of the figure, the shaft 5 is a piece of low-cut steel, which is screwed onto the stop 3.

Thus, by an axial traction on the shaft 5, the tensile force is transmitted to the stop. The stop therefore exerts a force on the tampon. By having a second stop, described later, against the free face of the pad, we compress axially the buffer between these two stops, and a radial expansion is thus generated buffer. Indeed, the pad is deformable, so we can vary its length. In addition, it is incompressible, a decrease in its length therefore implies a increase in its diameter. The axially compressed pad extends radially as and when the compression imposed on it, and radially stresses the tube in which it is inserted. The radial force is exerted by the buffer on the walls of the tube against which the periphery of the buffer abuts. Compression effort sufficient thus causes plastic deformation of the tube area to the right of the buffer. This gives a local increase in the diameter of the tube, as this is shown in Figure 2. In the absence of stress, the elastomeric pad quickly returns to its original geometry and can therefore easily be removed from the end of the tube after expansion.

Various particular embodiments of the nozzle according to the invention provide additional benefits. The tampon being a part intended to be compressed axially to obtain its radial expansion, a buffer is preferably chosen made of an elastomeric material, for its deformability and incompressibility properties, such as for example a silicone derivative or a polyurethane. In addition, for favor the homogeneity of the deformation of generally cylindrical tubes, it is preferable to use pads of substantially cylindrical shape because the pad thus comes directly into contact with the entire surface to be deformed. More generally, the pad section preferably corresponds to the inner section of the tube to be deformed, with a clearance allowing the introduction of the buffer into the tube.

It can also be interesting to check the hardness of the tampon. This ensures that the tampon can thus deform the tube homogeneously during its deformation, even in the event of a defect in the tube, or in the case where the outer section of the buffer is not exactly the same as that of the tube. A hardness between 50 and 110 Shore A seems particularly suitable. It is also best to choose a elastomer having good time resistance and good chemical resistance, in particular to resist greases and solvents commonly used in the trades construction.

The description has so far indicated the use of a one-piece pad. he it is however possible to vary the ratio between the length of tube to be deformed and the diameter to be obtained using a multi-ring buffer, composed of several stacked elastomer washers, between which it is possible to interpose non-deformable parts, such as metal washers 14. This puts on steel washers and elastomer washers on the shaft 5. The introduction of washers elastomers has no influence on the quality of the socket, because of the properties deformability of the elastomeric washers, these may completely cover the metal washers to cover the entire surface of the desired tube. The introduction washers ensures that the elastomeric pad formed of elastomeric washers and homogeneous radially deforms.

An additional advantage of the tampon according to the invention is that due to the deformability of the elastomeric pad, the junction 15 between the socket 16 and the rest of the tube is progressive and conical.

The stop 3 of the nozzle has the function of axially compressing one face of the pad, and more specifically the side of the pad which is pressed into the tube. Preferably, the stop is chosen with a circular compression face, of diameter substantially equal to the diameter of the tampon, so as to compress the most large pad area possible. In addition, the diameter of a cylindrical pad used is very close to the initial diameter of the portion of tube to be deformed. So if we uses a stop diameter close to the diameter of the buffer, an axial creep is avoided of the buffer during compression, harmful to the operation of the device. According to a particular embodiment, the stop is metallic to allow good transmission of the compression forces imposed on the buffer. We can finally realize a rounded projection on the free face of the tampon, to facilitate its insertion at inside the tube. The stop has fixing means on the shaft 5, so that transmit the forces exerted by the shaft to the elastomer pad.

The function of the shaft is to transmit a compression force of the mouthpiece. It can therefore have any shape. Having it in the center of the tampon avoids limiting the radial deformation of the tampon. At one end, the shaft has fixing means on the stop, in the example a thread of its end. We could also use a monobloc shaft with the stop, and for example simple to use as a shaft and as a stopper a screw: the rod of the screw would then serve shaft, while the head of the screw would serve as a stop.

The invention also provides a clamp 6 intended to exert traction on the shaft 5 of the nozzle and provide a stop complementary to the stop of the nozzle. The structure of this clamp will appear more clearly from the following description of operation of a tip coupled to a clamp. An example of realization of a such pliers are shown in FIG. 3. According to this exemplary embodiment, the pliers 6 comprises a body 7 with a handle 13, a lever 8, a piston 9, a link 10, a compression stop 11 and a dowel 17.

The body 7 is made of treated steel. It defines a cavity 12 passing through it in part, and is fixed to the end of a handle 13. The piston 9 is shaped to slide in the cavity 12 and protrudes from one end of the cavity. On a part protruding from this piston is mounted a pin 17, which serves for hooking the lever 8. The end of the lever 8 is fork shaped and has two ends parallel planes each with a recess into which one end of the pin 12. The lever can thus pivot around this pin, while driving it. Conversely, the lever 8 can easily be released from the end of the piston. A rod 10 pivots at one of its ends around an axis of lever 8, which is close of its fork shaped end. This link 10 pivots at its other end around an axis of the handle 13. This link can be doubled by one second rod placed symmetrically on the other side of the lever 8 and of the handle 13. The handle 13 is integral with body 7 and extends substantially radially relative to the common axis of the piston 9 and of the cavity 12. The second end of the cavity 12 is partially closed by a washer 11. This washer is drilled so as to leave pass the tree 5.

The piston has means for fixing the free end of the shaft to a mouthpiece. It can simply be a tapped hole, allowing the mounting of the shaft by screwing.

The operation of the clamp is as follows. A nozzle is fixed on the piston 9, the shaft passing through the hole of the washer 11. In this position, as shown in Figure 1, the tip pad is in contact with the washer of the clamp part and the stop on the other hand. It will be noted that for fixing the end piece to the piston, the lever 8 can be released from the end of the piston which projects from the body 7. This allows the piston to be rotated, or changed easily, for example if there are several types of trees with different attachment means.

Once the nozzle has been fixed, the lever 8 is hooked on the end of the piston. In this position, the nozzle can be introduced at the end of a tube; previously the tube if necessary, cut to the right length, well perpendicularly. The tip is pressed into the tube, so that the end of the tube comes into contact with the washer 11 of the clamp, and that the elastomeric pad is entirely in the tube. This configuration is shown in Figure 1.

With a few presses on the lever 8 and the handles 13, the shaft 5 is urged traction, which has the effect of compressing the buffer between the stop 3 and the washer 11, and thus increase the diameter of the buffer. It follows an expansion of the diameter of the tube to the right of these washers, and a plastic deformation of the tube.

When the lever 8 is released, the tampon ceases to be stressed, and can easily be removed from the deformed end of the tube.

In the case of a synthetic material tube, for assembly with a insert, it is preferable to insert the insert immediately after removing the clamp, because that the memory effect of the material tends to bring the part more or less quickly distorted to its original diameter. If there is a crimp ring, this is engaged on the tube before it is deformed, and it is brought back after deformation against the insert, using suitable mounting pliers.

The passage from one diameter to another is done by simple replacement of the end piece, by spacing the handles, detaching the end piece in place, and hanging it of the new tip.

• un ensemble d'embouts interchangeables adaptés aux différents diamètres de tubes. Ces embouts sont composés, par diamètre, d'un axe en acier décolleté sur lequel sont enfilées des rondelles acier et des bagues élastomères. Le gonflement de ces embouts permet l'expansion du diamètre intérieur des tubes aux dimensions souhaitées; pour chaque embout, la longueur de déformation peut simplement être réglée en modifiant le nombre de rondelles utilisées, lors du montage de l'embout sur la pince;
• un corps en acier usiné traité muni de poignées et d'un système d'accrochage pour la mise en place et le maintien des embouts.

The invention can also take the form of a set of tools comprising:

• a set of interchangeable tips adapted to different tube diameters. These end pieces are composed, by diameter, of a low-cut steel axis on which steel washers and elastomer rings are threaded. The swelling of these tips allows the expansion of the inner diameter of the tubes to the desired dimensions; for each end piece, the deformation length can simply be adjusted by modifying the number of washers used, when mounting the end piece on the clamp;
• a treated machined steel body fitted with handles and a hanging system for fitting and holding the end caps.

The tubes that can be formed with the tool are in particular copper tubes annealing with a diameter of 12 mm to 20 mm, or tubes made of synthetic materials from DN 12 to DN 25 in series 5, from DN 16 to DN 25 in series 3.2, tubes of minimum thickness from 2mm from DN12 to DN22, or the metal core composite tubes from DN 14 to DN22. One can in particular use the tubes marketed by the applicant under the RETUBE brand, which are cross-linked polyethylene tubes.

The following table shows examples of characteristics of tubes to be enlarged, as well as the dimensions of these tubes after expansion according to the invention: DN 5 series 2 mm mini series 3.2 series DImini Dexp Lexp DImini Dexp Lexp DImini Dexp Lexp 12 9 10.85 11 7 8.75 11 16 12.2 14.05 11 11 12.85 11 10.6 12.35 11 20 15.4 17.25 11 15 16.85 11 13.4 14.95 11 25 19.4 21.8 16.4 19.4 21.8 16.4 17 18.55 16.4 DN Nominal outside diameter of the tube. DImini Minimum inside diameter of the tube. Dexp Internal diameter of the tube after expansion. Lexp Expanded tube length.

Dexp = diamètre embout +0.2/+0.25 mm

Lexp=L embout +/-0.5 mm

During the five seconds following the expansion, we can see, for this type of pipe, the following relationships:

Dexp = tip diameter + 0.2 / + 0.25 mm

Lexp = L tip +/- 0.5 mm

The socket produced according to the invention reduces the risk of thinning or localized bleaching. The invention makes it possible to reduce the risk of producing sockets defective. The socket has an expansion of uniform diameter over the entire periphery of the tube, with an absence of any generator preferably requested.

The progressive deformation of the buffer allows for a bottom case conical, which is particularly useful when using inserts fitting, such as barbed fitting inserts. The bottom cone allows thus forming a stop for the insert. This cone also allows the wedging of this insert and thus prevents the fitting from dropping unexpectedly during handling phases later.

The invention is of course not limited to the embodiments described. In particular, it is conceivable within the framework of the invention, to integrate the tree of the end piece in the pliers, to produce a stopper washer 11 detachable from the pliers or of the tip or even a tip integrating the two stops described.

Claims (9)

Snap-in pliers comprising: a tip with: an elastomeric pad (4); an axial stop (3); a shaft (5) passing through said pad (4), the shaft (5) driving the stop (3) in translation towards the pad when it is stressed; a thrust washer (11) pierced with a hole through which the shaft (5) passes; traction means (7, 8, 9, 10, 12, 13, 17) of the shaft (5), facing the hole, characterized in that :
the traction means have: a body (7) with a handle (13) and a through cavity (12) formed in the body (7), said thrust washer (11) substantially closing one end of the cavity; a piston (9) sliding in said cavity (12), in which are provided means for coupling the shaft; a movable lever (8) rotatably mounted on the handle (13) and one end of which biases the piston (9). The socket pliers of claim 1, characterized in that the end (8) of the lever is separable from the piston (9). The clamp of claim 1 or 2, characterized in that the lever (8) is rotatably mounted on the handle (13) by means of at least one link (10). The socket pliers of one of claims 1 to 3, characterized in that the pad (4) is of substantially cylindrical shape. The socket pliers of one of claims 1 to 4, characterized in that the stop (3) has a circular face of diameter substantially equal to the diameter of the pad (4). The socket pliers of one of claims 1 to 5, characterized in that the stop (3) is metallic. The socket pliers of one of claims 1 to 6, characterized in that the pad (4) comprises several elastomeric washers. The socket pliers of claim 7, characterized in that metal washers (14) are interposed between elastomeric washers. The socket pliers of one of claims 1 to 8, characterized in that each pad (4) has a hardness between 50 and 110 Shore A.

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