Gasket for forming end flaring in pipe made of thermoplastic material

Abstract

The invention describes a gasket for forming end flares in pipe fittings (100) made of a thermoplastic material, in particular PVC-U, each pipe fitting having a first end (110) intended to be flared (101); the gasket (1) comprises: a body (10) configured to at least partially mate with a first end (110) of a pipe (100) and having a longitudinally extending main axis (X); the body (10) comprises a front portion (8) and a rear portion (7), the front portion (8) having at least one end element (12) designed to form a tapered portion (102) of a first end (110) of the tube (100); the body (10) having a compartment (4) designed to receive a plurality of inserts (3) and means (5) for moving the inserts (3) configured to move the inserts (3) between a retracted position (P1), in which they are positioned inside the compartment (4), and a deployed position (P2), in which at least a portion of the inserts (3) are positioned outside the compartment (4); the insert (3) is inserted between the front portion (8) and the rear portion (7) of the body (10); the main body (10) comprises a bearing shaft (6) supporting the main body (10) and means (5) at least for moving the insert (3), which means extend parallel to a longitudinally extending main axis (X); the forming liner (1) comprises a system (23) for cooling the body (10); the cooling system (23) comprises a plurality of conduits (230) for conveying the liquid (80), which conduits extend at least partially in the rear portion (7) of the body (10), in the front portion (8) of the body (10) and in the carrier shaft (6).

Description

Technical Field

[0001] The present invention relates to a gasket for forming an end flare in a pipe made of thermoplastic material. Background Art

[0002] When producing by thermoplastic extrusion pipe fittings designed for the manufacture of pipes for conveying and / or discharging fluids, such as drainage networks and drinking water distribution networks for construction projects, the end portions of the pipe fittings are formed into a characteristic "flared" shape using a flaring machine. This wider shape is used to connect the pipe fittings to one another in succession to form a pipeline. In fact, the unformed end of the pipe fitting is usually inserted into the flared end of an adjacent pipe fitting in the pipe fitting. The flared portion can be cylindrical, designed for a simple snap-on connection with or without bonding, or it can include a seat for an elastomeric gasket designed for a gas-tight seal of the joint.

[0003] Most belling machines make the belled portion by thermoforming. They are equipped with one or more heating stations to heat the end of the tube, bringing the wall to be formed into a softened state that is plastically deformable. The forming device then forms the heated end of the tube into the belled shape by using a suitable die and cools the belled shape on the die. The belling machine installed in the extrusion line comprises an operating head equipped with at least one oven for heating the tube, and a forming device associated with a workbench provided with movement means, on which the tube to be processed is progressively developed in a continuous cycle.

[0004] In all types of expanding machines, the various tube elements, consisting of rectilinear pieces, are processed one after another after being introduced into the table of the machine in a direction coinciding with the longitudinal axis of the tube. After reaching the table, they are translated transversely with respect to the direction in which they arrived, intermittently making step-like movements, remaining parallel to one another. During the stops between one step and the next, the tube undergoes a separate processing which essentially consists in heating the end to be formed in an oven and then forming the flared portion. In addition to forming the flared portion, the cooling of the flared portion is also carried out simultaneously in the same forming station. Both the heating step and the forming step are carried out by associating an oven and a device for forming the tube by means of a carriage, which is appropriately moved according to the various operating steps, moving the oven and the forming device towards and away from the tube.

[0005] The machines that make up the extrusion line are designed to process tubes of different sizes within a relatively large size range. Considering the belling machine, different elements in the machine must be replaced as the diameter size of the tube changes. Among these interchangeable elements, the dies designed to form the end belling integrated in the tube are of great importance.

[0006] The process of forming the flared portion depends largely on the material of the pipe fitting; therefore, the shape of the mold also depends on the material of the pipe fitting. The most commonly used thermoplastic materials in pipe fitting systems are unplasticized polyvinyl chloride (PVC-U), polypropylene (PP) and high-density polyethylene (HDPE). Among them, PVC-U pipe fittings are used in underground drainage pipe fitting systems, especially sewage pipe fittings.

[0007] In PVC-U pipe fittings, a metal mold in the shape of a cylindrical spindle is usually used to shape the inside of the flared part into a smooth cylindrical shape. These spindles are called smooth liners, because the outer surface of the liner reproduces the smooth cylindrical shape of the flared part to be connected, and the part of the flared part that is connected to the pipe fitting has a smooth conical shape. The smooth liner is inserted into the end of the pipe fitting, which has been softened by previous heating, and the end of the pipe fitting adopts the shape and size of the smooth liner by mechanical action, or by the simultaneous action of compressed air outside the flared part or vacuum inside the flared part. When the flared part is formed and cooled, the smooth liner is removed from the flared part.

[0008] As is known, for PVC-U pipe fittings, two different flared portion forming technologies are used: the Rieber system and the mechanical gasket system to form the flared portion with a gasket internally.

[0009] With the Rieber system, the gasket is preloaded in the die and, at the end of the flaring process, is integrated into the wall of the flared section; it is therefore non-removable and can no longer be replaced in the finished flared section. In the Rieber system, the metal die is shaped like a smooth gasket, but it is equipped with a housing for the gasket. The gasket and the associated housing are shaped so that when the flared section is formed and cooled, the gasket is removed from the flared section and the gasket remains locked in the flared section.

[0010] In the mechanical lining system, the die is a metal spindle, also called a mechanical liner, which has an outer surface configured to form the shape of the seat for the gasket in the wall of the flared part. The gasket will thus be inserted into the finished flared part, in any case the gasket in the flared part being removable and replaceable. In short, in the mechanical lining flaring system, the end of the pipe, which has been softened by previous heating, is inserted into the liner, and the end of the pipe adopts the shape and size of the liner by the action of compressed air outside the wall of the pipe or vacuum inside the wall of the pipe. When the flared part has been formed and cooled, the liner is removed from the flared part. In order to allow the liner to be removed from the flared part, the liner part that reproduces the seat of the gasket includes a deployable insert that is completely retracted in the liner body by means of a mechanism and an associated drive, thereby allowing the liner to be removed from the flared part with the retraction of the insert.

[0011] PVC-U pipe fittings for sewage pipes mainly use pipe fittings with a flared portion, which includes a square-shaped gasket seat. The flared portion has a high level of internal dimensional accuracy, which can only be achieved through mechanical lining technology.

[0012] The mechanical gasket comprises a tubular body provided with a circumferential opening along the side surface facing a compartment inside the tubular body. The compartment houses a plurality of metal sectors, also called inserts, which are bent outwards according to the seat to be made on the tube. The inserts are moved between two positions by means of actuators and mechanisms inside the gasket: in the deployed position the continuity of the metal outer surface of the mould is achieved, which reproduces the internal shape of the cup; in the retracted position they completely disappear inside the gasket body. Among the numerous configurations of the mechanisms for moving the inserts, important configurations are described in patent documents EP0052581, US4395218, IT1180547, DE2515461 and DE2758188; currently, the most commonly used insert movement mechanisms are rotary cam mechanisms and wedge mechanisms, which classify mechanical rotary cam gaskets and mechanical wedge gaskets, respectively.

[0013] In a rotary cam pad, the movement of the insert is achieved by a number of cams opposite each other, which are positioned in circular symmetry around the axis of the pad. Each pair of cams is attached to the insert. All cams are keyed to a single shaft coaxial with the body of the pad, called the camshaft. With the aid of actuation, the shaft of the cams rotates to determine the two angular positions of the cams, which impose the extended and retracted positions of the insert.

[0014] In a wedge-shaped pad, a "wedge" element is connected to the insert and slides coaxially in two directions inside the pad body, without the possibility of relative rotation, by means of a jack drive and a rod rigidly connected to the plunger of the jack. The wedge translates between two axial positions which respectively impose the extended and retracted position of the insert.

[0015] The common feature of cam pads and wedge pads is the presence of a first plurality of inserts, the cross section of the first plurality of inserts being substantially triangular and bent outwards according to the seat to be made on the tube, and a second plurality of inserts, the cross section of the second plurality of inserts being substantially trapezoidal and bent outwards like the first plurality of inserts, alternating with the preceding inserts. The specific shape of the inserts allows mutual sliding of the associated side walls during expansion and retraction, which results in the so-called self-cleaning phenomenon of the parts in contact with the inserts. Cam pads are characterized in that the geometry of the cam is specific to the first plurality of inserts, and the geometry of the cam is specific to the second plurality of inserts, which is different from the first plurality of inserts. In mechanical wedge pads, such as those described in patent documents EP0052581, US4395218, IT1180547, the wedge is provided with a first and a second series of equidistant guides at the periphery, which extend alternately with each other along the generatrix of the wedge. The first plurality of inserts is coupled to the guides of the first series by bilateral constraints. The second plurality of inserts are simply placed onto the underlying respective guides of the second series.

[0016] In both cam pads and wedge pads, the pad body is supported by a central bearing shaft. The pad body consists of two parts, front and rear, rigidly joined to the bearing shaft and separated by an insert compartment. The outer surface of the rear part of the pad body forms the end edge of the flared portion, while the outer surface of the front part forms the cylindrical portion of the flared portion and the conical portion joined to the pipe. In cam pads, the bearing shaft performs the function of constraining and guiding the insert, and in its longitudinal extension it has a cavity that encloses the rotating movable shaft of the cam coaxial with the bearing shaft. In wedge pads, the bearing shaft performs the function of constraining and guiding the wedge in its translational movement.

[0017] During the expansion process of PVC-U pipe fittings, the formation of the expanded part at the end of the pipe fitting in a hot state occurs at a temperature of 105°C-140°C, which is the optimal temperature for inserting the liner at the end of the pipe fitting, and is therefore higher than the glass transition temperature of PVC-U (about 80°C), so that the wall of the pipe fitting is plastically deformable. After the inner end of the pipe fitting adopts the shape of the liner, when the temperature of the PVC-U reaches a value below the glass transition temperature, the expanded part becomes rigid and dimensionally stable. In the expansion process, the wall temperature of the expanded part at the end of cooling is lower than 55°C, usually in the range of 40°C-50°C.

[0018] The internal geometric and dimensional accuracy of the flared part required for the function of the joint is very high; therefore, it is important to limit the spontaneous dimensional shrinkage of the flared part when it is removed from the gasket, which is caused by the decrease in the specific volume of the material with the decrease in temperature. During the flaring process of PVC-U, the dimensions of the gasket are usually designed to take into account the spontaneous shrinkage of the flared part removed from the gasket relative to the optimal internal dimensions of the flared part at an ambient temperature of 23℃±2℃, which is 0.35%-0.45%. The shrinkage corresponds exactly to the volume shrinkage determined in the thermal equilibrium channel of 45℃-55℃ to 23℃ in PVC-U.

[0019] In addition, the diameter contraction of the flared portion is not uniform around the circumference of the flared portion because the thickness of the tube wall produced by extrusion is not uniform. For example, a tube with a nominal outer diameter of 110 mm and a nominal minimum wall thickness of 3.2 mm is considered to be satisfactory and usable when the wall thickness varies within the range of 3.2 mm-3.7 mm. The variation in wall thickness results in a greater ovalization of the finished flared portion the greater the thermal jump that the flared portion removed from the liner must undergo in order to reach ambient temperature during the cooling of the flared portion removed from the liner. The effect of ovalization will be more obvious if the cooling of the flared portion formed on the liner during the flaring process is not uniform around the circular extension of the flared portion. Similarly, if the cooling during flaring is not uniform in the longitudinal direction of the flared portion, the flared portion removed from the liner will undergo a conical deformation.

[0020] The efficiency of the cooling and flaring process step is a decisive factor for the economic output of the flaring machine, since for the marketing of the flared pipes, a certain accuracy of the flared part is required in terms of shape and size established for the function of the flared part joint. Moreover, the greater the economic output potential of the flaring machine, the faster the machine's production speed.

[0021] As mentioned above, it is important to make the machining of the cooling flared portion uniform in both the circular and axial extensions of the flared portion and to quickly bring the flared portion into conformity with the operating requirements.

[0022] The flaring system for forming a smooth Rieber flared portion uses a smooth liner mold without internal mechanisms; it is therefore simple and advantageous to construct the liner body with an inner cavity that is axially symmetrical with respect to the liner axis and to circulate a cooling liquid in this cavity. Conveniently, the cooling liquid is water mixed with ethylene glycol, distributed by an autonomous cooling machine connected in a closed circuit to the flaring machine, or the hydraulic circuit of the flaring machine is connected to a centralized cooling system that can serve several machines of a plant for the production of plastic pipe fittings. The symmetrical configuration of the inner cavity of the liner, in which the cooling liquid flows, favors uniform cooling in the circular extension of the flared portion, which is therefore optimal for minimizing the ovalization of the flared portion.

[0023] In the belling machine, in order to make the cooling step faster, both conduction cooling is carried out by direct contact of the wall of the belled part with the cold metal wall of the liner and a convection cooling system is activated by means of air and / or water to act on the outer wall of the belled part being formed. The air can be ventilated or pre-cooled compressed. In most belling machines with the highest performance levels, the external cooling system by convection has atomized or sprayed water distribution with compressed air.

[0024] The liner cooled with coolant is suitable for multiple flaring machine configurations. During multiple flaring, the flaring machine picks up the tubes from the extrusion line each time and accumulates them in groups of two or more tubes. Several groups of tubes transferred and processed at various stations are used for heating and forming cooling of the flaring machine, which has a clear advantage in the number of processed tubes over time.

[0025] However, the multiple flare configuration does not facilitate uniform external convective cooling of the circular extension of the flared portion, nor uniform cooling of all the tubes of the multiple flare group. In fact, in a separate cooling chamber enclosing all the tubes of the multiple flare unit, the internal tubes in the multiple flare unit are exposed to the convective cooling fluid in a different manner than the transverse tubes of the unit. Even if there are multiple cooling chambers, i.e., a separate cooling chamber for each tube of the multiple flare unit, it is technically difficult to evenly distribute the convective flow in the various chambers, especially when the convective flow is completely or partially gaseous.

[0026] The cooling of the flared part, which is achieved by conduction through a smooth liner provided with internal cooling water circulation, is not subject to the above-mentioned disadvantages. In fact, in order to limit the effects of ovalization of the flared part and to maintain high production capacity values, it is sufficient to make the cooling contribution inside the flared part by conduction more prevalent than the cooling contribution outside the flared part by convection.

[0027] However, in mechanical liner expansion systems, the method of cooling the liner with internal circulation of a coolant is prevented by the construction of the deployable sectors and the movement mechanism of the insert occupying the inner body of the liner. The internal cooling mode of mechanical liner occurs with the aid of compressed air and / or ventilation, which enters from the rear part of the liner and is then discharged from the front end of the liner. The cooling air is usually preheated in a radiator or heat exchanger. Therefore, the air cooling capacity is much smaller than that of water. In order not to impair the performance of the expansion machine, even at the expense of increasing the consumption of compressed air and / or electricity, over time, advanced cooling systems have been introduced that combine the convection treatment of the outside of the expansion with the internal cooling of the liner by air. These systems, such as those described in patent documents EP0516595, EP0684124 and EP2189268, have proven to be particularly effective and widely used in mechanical liner expansion machines.

[0028] Over time, the technology for heating the ends of the tubes has evolved in terms of the speed of the heating step in the flaring process, so that in a mechanical liner flaring system, the limit on the minimum time required to perform a flaring cycle is set by the minimum time to cool the flared section formed on the liner. Shorter times will emphasize the gradual overheating of the mechanical liner until the maximum acceptable temperature for making the flared section according to the operation requirements is exceeded.

[0029] This technical limitation is particularly critical in the production of PVC-U pipe fittings for sewage pipes, which feature a flared section with a seat for a square gasket made with mechanical lining technology. In fact, in the field of PVC-U sewage pipe fittings, smaller diameter pipes such as 110mm, 125mm, 160mm and 200mm outer diameters are used, so the market needs these pipes, especially relatively short lengths, that is, nominal commercial lengths of 1000mm and 500mm plus the flared section. Therefore, at the same extrusion speed, the shorter the length of the pipe, the greater the number of pipes that the flaring machine must receive and process over time. The molding of the flared section with mechanical lining guarantees the high quality of the flared section, but using modern extrusion systems, a single flaring machine cannot support production plans involving small diameters and short pipes.

[0030] When matched to market demand, a less onerous production schedule is drawn up for flaring, in which the production of short tubes is carried out simultaneously with the production of long tubes. If even this situation is not sufficient to be handled with a separate flaring machine, two or more flaring machines are installed, independent of each other, or two or more flaring machines are integrated in a single machine, in which the operating stations of the two or more flaring machines are positioned in parallel but served by a separate workbench for moving the tubes. A mechanical liner flaring machine capable of working in a multi-flaring mode would be advantageous, but the possibility of such a development is excluded according to the current prior art for the reasons mentioned above, in particular due to the lack of a system for cooling the inside of the liner with a coolant, making internal cooling of the flared section more effective than external convection cooling of the flared section. Summary of the invention

[0031] Under this background, there is a need to provide a liner for forming an end flared portion on a pipe made of thermoplastic material, in particular PVC-U, to solve the above-mentioned disadvantages.

[0032] The object of the present invention is to provide a gasket for forming an end flared portion on a pipe made of thermoplastic material, in particular PVC-U, which reduces the time for cooling the formed flared portion compared to conventional mechanical gaskets, thereby improving production capacity.

[0033] Another object of the present invention is to provide a gasket for forming an end flared portion on a pipe made of thermoplastic material, particularly PVC-U, which gasket uniformly cools the formed flared portion in a circular extension of the flared portion and performs a mechanical gasket-like flaring process in a multi-flaring mode. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The technical features of the present invention are clearly described in the claims with reference to the accompanying drawings, and its advantages are obvious from the following specific embodiments. The accompanying drawings only provide preferred embodiments of the present invention by way of example, and do not limit the scope of the inventive concept. In the accompanying drawings:

[0035] - Figure 1 A pipe member is shown which is expanded by means of a gasket and an expander for forming an end expanded portion in a pipe member made of a thermoplastic material according to the present invention;

[0036] - Figure 2A and 2B Schematic front view and side cross-sectional view, respectively, of a forming liner according to the present invention;

[0037] - Figure 3 yes Figure 2B A schematic cross-sectional view of a forming pad in FIG. 1 with some details highlighted;

[0038] - Figure 4A and 4B is a cross-sectional view showing a schematic diagram of details of the belling machine and the PVC-U thermoplastic pipe fitting in a disengaged state and an engaged state, respectively;

[0039] - Figure 5 is a schematic illustration of a cross-sectional view of a belling machine operating on a thermoplastic pipe made of PVC-U;

[0040] - Fig. 6A is a perspective view of a first embodiment of a forming pad according to the present invention;

[0041] - Figure 6B and 6C It is shown Fig. 6A A perspective cutaway view of an embodiment of a forming liner according to the present invention shown in FIG.

[0042] - Fig.6D yes Fig. 6A A perspective cutaway view of some details of the forming liner shown in ;

[0043] - Fig. 6E and 6F is a cross-sectional view showing Fig. 6A Some details of the forming pad shown in different operating positions;

[0044] - Fig. 7A is a perspective view of a second embodiment of a forming pad according to the present invention;

[0045] - Figure 7B and 7C It shows Fig. 7A A cross-sectional view of an embodiment of a forming liner shown in ;

[0046] - Fig.7D and 7E is a cross-sectional view showing Fig. 7A Some details of the forming liner shown in different operating positions;

[0047] - Figure 7F Shows Fig. 7A Details of the formed liner;

[0048] - Figure 7G Shows Figure 7F two cross-sectional views of details of a forming liner;

[0049] - Fig. 8A is a perspective view of an embodiment of a belling machine;

[0050] - Figure 8B yes Fig. 8A A perspective cutaway view of the belling machine shown in;

[0051] - Fig. 9 is a cross-sectional view of an embodiment of a belling machine;

[0052] - Fig.10 is a cross-sectional view of an embodiment of a belling machine;

[0053] - Fig.11 It is a schematic block diagram of a belling machine. DETAILED DESCRIPTION

[0054] Referring to the drawings, numeral 1 denotes a gasket (hereinafter also referred to as a forming gasket 1 or a gasket 1 for short) for forming an end flared portion in a pipe 100 made of a thermoplastic material, particularly PVC-U.

[0055] Each tube 100 has a first end 110 intended to be formed as a flared portion 101 .

[0056] like Figure 1 As shown in the figure, the first end portion 110 of the pipe 100 formed with the flared portion 101 has a tapered portion 102 connecting the flared portion 101 and the pipe 100, a cylindrical portion 103 adjacent to the tapered portion 102, a cylindrical portion 104 at the end of the flared portion 101, and a portion 105 inserted between the cylindrical portions 103 and 104 and configured to accommodate a gasket.

[0057] In other words, if Figure 1 As shown in FIG. 1 , the portion 105 of the flared portion 101 is a cylindrical portion having a radius greater than the radius of the cylindrical portions 103 and 104, thereby defining a seat for the gasket. For example, the seat may be a square-shaped seat, but the scope of the invention is not limited thereto.

[0058] According to the invention, the mechanical gasket 1 comprises a body 10 of substantially cylindrical shape with a main axis X extending longitudinally, configured to at least partially cooperate with a first end 110 of a pipe 100 .

[0059] The body 10 has a compartment 4 designed to accommodate a plurality of inserts 3 and means 5 for moving the insert 3 .

[0060] In other words, the compartment 4 for housing the insert 3 is formed in the body 10 of the pad 1 .

[0061] The movement device 5 is configured to move the inserter 3 between a retracted position P1 , in which the inserter 3 is at least partially positioned inside the compartment 4 , and a deployed position P2 , in which at least a portion of the inserter 3 is positioned outside the compartment 4 .

[0062] According to one aspect of the present invention, the inserting member 3 is divided into a first inserting member 3A and a second inserting member 3B, which are alternated with each other and are both bent outward.

[0063] The main body 10 includes a front portion 8 and a rear portion 7 .

[0064] According to the invention, the insert 3 is inserted between the front portion 8 and the rear portion 7 of the body 10 .

[0065] The body 10 comprises a bearing shaft 6 supporting the body 10 and at least means 5 for moving the insert 3 , which extend parallel to a main axis X extending longitudinally.

[0066] In the drawings, for quicker understanding, the second axis Y and the third axis Z are further defined as being perpendicular to each other and to the main axis X extending longitudinally.

[0067] According to one aspect of the invention, the rear portion 7 and the front portion 8 of the body of the pad 10 are two separate tubular pieces, which are assembled coaxially to each other by means of a bearing shaft 6 and known locking means 29 .

[0068] The carrier shaft 6 has a contact surface 9 which is configured to fix the front part 8 and the rear part 7 to each other.

[0069] The front part 8 and the rear part 7 are assembled to form a compartment 4 for housing the insert 3 .

[0070] In other words, the front portion 8 and the rear portion 7 have respective surfaces 11, perpendicular to the main axis X extending longitudinally and facing each other, and the mutual arrangement of said portions 8, 7 defines between the surfaces 11 a circumferential opening of a width suitable for housing the insert 3, i.e. the compartment 4. The surface 11 is also configured to allow the insert 3 to slide between a retracted position P1 and a deployed position P2.

[0071] The front portion 8 of the body 10 has at least one end element 12 intended to form a tapered portion 102 of a first end 110 of the pipe 100 .

[0072] According to a preferred embodiment, the end element 12 is detachably connected to the front portion 8 of the body 10 .

[0073] The end element 12 comprises part of a tapered outer surface 13 which is configured to define a tapered portion 102 of a first end 110 of the pipe 100 in use.

[0074] In other words, the tapered outer surface 13 of the end member 12 corresponds to the tapered portion 102 connected to the flared portion 101 of the pipe 100 .

[0075] The end member 12 includes a tapered nose portion 12A configured to be inserted into the pipe 100 .

[0076] It should be noted that the diameter of the tapered nose portion 12A of the end element 12 is smaller than the inner diameter of the pipe 100. Advantageously, the end element 12 is inserted into the pipe 100 without interference.

[0077] Advantageously, the end element 12 is removable relative to the body 10, since for the same outer diameter and flared portion, the pipe 100 can have different thickness size grades and thus different inner diameter values. Therefore, as the thickness of the pipe 100 being processed changes, in order to make the flared portion 101 in the pipe 100, it is not necessary to replace the entire mechanical liner 1, but it is sufficient to replace the end element 12.

[0078] For example, among PVC-U sewage pipe fittings 100 with a nominal outer diameter of 110 mm, there are fittings 100 with minimum nominal thicknesses of 3.2 mm and 4.0 mm, both of which are made of flared portions 101 of equal shape and inner dimensions. The liner 1 will have two end members 12: one suitable for forming a fitting 100 with a thickness of 3.2 mm and the other suitable for forming a fitting 100 with a thickness of 4.0 mm.

[0079] According to the invention, the pad 1 comprises a system 23 for cooling the body 10 .

[0080] The cooling system 23 comprises a plurality of ducts 230 for conveying the liquid 80 , which ducts extend at least partially in the rear portion 7 of the body 10 , in the front portion 8 of the body 10 and in the carrier shaft 6 .

[0081] Preferably, the delivery pipes 230 are connected to each other by a coupling comprising a gas-tight sealing element of the prior art.

[0082] The liquid 80 is, for example, water or a cooling liquid in a non-limiting manner.

[0083] According to a preferred non-limiting embodiment, the liquid 80 is a solution of water and ethylene glycol, pressurized at a pressure of 3-4 bar and thermally controlled at 8-12° C. by a chiller outside the pad 1 .

[0084] Advantageously, the extension of the duct 230 for conveying the liquid 80 into the rear portion 7 , into the front portion 8 and into the bearing shaft 6 of the body allows the liquid 80 to reach various parts of the pad 1 , even with separate circulations through said conveying duct 230 .

[0085] According to the invention, the conduit 230 for conveying the liquid 80 comprises at least a first annular chamber 15 made in the rear portion 7 of the body 10 and a second annular chamber 16 made in the front portion 8 of the body 10 .

[0086] The first annular chamber 15 and the second annular chamber 16 extend at least partially around a main axis X extending longitudinally of the body 10 .

[0087] According to one aspect of the invention, the body 10 comprises side walls 14 both at the front portion 8 and at the rear portion 7 .

[0088] The side wall 14 of the body 10 is configured to define a first annular chamber 15 in the rear portion 7 and a second annular chamber 16 in the front portion 8 .

[0089] It should be noted that the first chamber 15 and the second annular chamber 16 are located on opposite sides of the body 10 relative to the compartment 4 .

[0090] The annular chambers 15 and 16 extend in size so that the movement means 5 of the insert 3 can be actuated without interference.

[0091] According to the invention, the conduit 230 for conveying the liquid 80 comprises at least one conveying conduit 32 and at least one return conduit 35 inside the bearing shaft 6 and has a main extension direction parallel to the main axis X extending in the longitudinal direction of the body 10 .

[0092] The delivery conduit 32 is in fluid communication with the first annular chamber 15 and the second annular chamber 16 .

[0093] The delivery conduit 35 is in fluid communication with the second annular chamber 16 .

[0094] Advantageously, the delivery duct 32 and the return duct 35 extending in the carrier shaft 6 allow fluid communication between at least a portion of the duct 230 located in the rear portion 7 and at least a portion of the duct 230 located in the front portion 8 .

[0095] Advantageously, the arrangement of the delivery duct 32 and the return duct 35 inside the bearing shaft 6 allows fluid communication between the ducts 230 located in the rear portion 7 and the front portion 8 to pass through the compartment 4 for housing the insert 3 and its movement means 5 without interference.

[0096] Preferably, the supply duct 32 and the return duct 35 are parallel to the main axis X extending longitudinally.

[0097] According to one embodiment, the delivery duct 32 and the return duct 35 are longitudinal holes made directly in the body of the bearing shaft 6 , passing through the ends and closed at the ends by a plurality of caps 17 .

[0098] Advantageously, the delivery duct 32 and the return duct 35 formed as longitudinal through holes facilitate cleaning and maintenance of the bearing shaft 6 and the pad 1 .

[0099] According to an alternative embodiment, in the case of a hollow load-bearing shaft 6 , the delivery duct 32 and the return duct 35 may be flexible or rigid ducts inserted into a cavity of the load-bearing shaft 6 .

[0100] According to a preferred aspect of the present invention, the conduit 230 for conveying the liquid 80 comprises an inlet opening 21 for the liquid 80 in fluid communication with the first annular chamber 15 and an outlet opening 22 for the liquid 80 in fluid communication with the second annular chamber 16 .

[0101] Preferably, the inlet opening 21 and the outlet opening 22 for the liquid 80 are positioned in the rear portion 7 of the body 10 .

[0102] The following special reference Figure 3 Described is a preferred, non-limiting embodiment of the cooling system 23 and, more specifically, the path followed by the liquid 80 within the pad 1 by means of a plurality of conduits 230 (hereinafter also referred to as conduits 230 ) defined for conveying the liquid 80 .

[0103] The conduit 230 comprises: - a first channel 30 extending from the inlet opening 21 of the liquid 80 to the first annular chamber 15;

[0104] - a second channel 31 which extends from the first annular chamber 15 to the delivery duct 32;

[0105] a third channel 33 extending from the delivery duct 32 to the second annular chamber 16;

[0106] a fourth channel 34 extending from the second annular chamber 16 to the return duct 35 ;

[0107] A fifth channel 36 which extends from the return duct 35 to the outlet opening 22 for the liquid 80 .

[0108] More specifically, “a channel extends from one conduit to another conduit” means that the channel fluidically connects one conduit to another conduit. In other words, this embodiment defines a path for loading and unloading liquid 80 relative to the first annular chamber 15 and the second annular chamber 16.

[0109] Special References Figure 3 The continuous arrow line indicates the path for loading the liquid 80 into the annular chambers 15 and 16 , and the dotted arrow line indicates the path for discharging the liquid 80 from the annular chambers 15 and 16 .

[0110] The duct 230 includes the following small passages inside and transverse to the load-bearing shaft 6:

[0111] a first transverse channel 37 configured to put the second channel 31 in fluid communication with the delivery duct 32;

[0112] a second transverse channel 38 configured to put the delivery duct 32 in fluid communication with the third channel 33;

[0113] a third transverse channel 39 configured to put the fourth channel 34 in fluid communication with the return duct 35 ;

[0114] A fourth transverse channel 40 , which is designed to put the return line 35 in fluid communication with the fifth channel 36 .

[0115] The first annular chamber 15 has a first hole 41 configured to place the first annular chamber 15 in fluid communication with the second passage 31 .

[0116] The second annular chamber 16 has a second aperture 42 configured to place the second annular chamber 16 in fluid communication with the fourth passage 34 .

[0117] More specifically, in the depicted embodiment, the path of liquid 80 within liner 1 is illustrated by conduit 230 .

[0118] The liquid 80 is supplied to the first annular chamber 15 through the first channel 30 in fluid communication with the inlet opening 21 and the first channel 30 is preferably positioned at a height below the axis X in use. The liquid 80 fills the first annular chamber 15 up to the height determined by the first hole 41. Preferably, in use, the first hole 41 is positioned at the maximum possible height above the axis X. In fact, the height position of the first hole 42 establishes the limit for filling the first annular chamber 15 and it is convenient to achieve a maximum filling of the chamber 15 in order to maximize the cooling effect of the pad 1. The first hole 41 delivers the liquid to the delivery duct 32 through the second channel 31 and the first transverse channel 37 formed in the bearing shaft 6, which is used to deliver the liquid 80 to the second annular chamber 16. Therefore, the liquid 80 from the first annular chamber 15 flows through the delivery duct 32 to the second transverse channel 38 connected to the third channel 33. The third channel 33 allows the liquid 80 to flow to the second annular chamber 16 through the connection, which is preferably positioned at a height below the axis X in use. The second annular chamber 16 has a second outlet opening 42 for the liquid 80, which is positioned in use as high as possible above the axis X to ensure maximum filling of the second annular chamber 16. The liquid 80 flowing out of the second annular chamber 16 reaches the return duct 35 via the fourth channel 34 and the third transverse channel 39. The liquid 80 reaches the fifth channel 36 via the fourth transverse channel 40, which is connected to the outlet opening 22.

[0119] According to one aspect, outside the pad 1 , the inlet opening 21 and the outlet opening 22 are connected to a cooling machine also outside the pad 1 by means of known elements (pipes and connectors).

[0120] Advantageously, the liquid 80 circulating in the first annular chamber 15 and the second annular chamber 16 contributes to the transfer of heat by conduction from the wall of the flared portion 101 to the chambers 15, 16. The transfer of heat and therefore the cooling of the flared portion 101 are particularly effective in the cylindrical portions 103 and 104 adjacent to the portion 105 of the flared portion 101. In fact, the cylindrical portions 103 and 104 machined for forming the pipe 100 are in contact with the wall of the body 10 which delimits the annular chambers 15, 16 cooled by the liquid 80 that circulates continuously.

[0121] According to one aspect of the present invention, the cooling system 23 includes one or more inlet branches 45 for the gaseous fluid 82, which extend in the rear portion 7 of the main body 10 from an inlet opening 451 toward one or more outlet openings 452 leading to the compartment 4, and one or more outlet branches 46 for the gaseous fluid 82, which extend in the front portion 8 of the main body 10 from an inlet opening 461 connected to the compartment 4 toward one or more outlet openings 28 leading to the external environment.

[0122] In other words, the inlet branch 45 delivers the gaseous fluid 82 to the compartment 4 through the inlet opening 451 of the inlet branch 45 .

[0123] Similarly, the outlet branch 46 delivers the gaseous fluid 82 from the compartment 4 through the inlet opening 461 of the outlet branch 46 and through the outlet opening 28 to the external environment.

[0124] Advantageously, the gaseous fluid 82 delivered by the inlet branch 45 and the outlet branch 46 allows the zone of the pad 1 in which it circulates to be cooled.

[0125] According to one aspect of the invention, the outlet opening 452 of the inlet branch 45 of the gaseous fluid 82 is configured to distribute the gaseous fluid 82 onto the surface portion 47 of the first annular chamber 15 facing the compartment 4 .

[0126] The inlet branch 45 has an opening 18 which is configured to convey the gaseous fluid 82 towards the surface portion 47 of the first annular chamber 15 .

[0127] Advantageously, by means of the outlet opening 452 , the gaseous fluid 82 cools the compartment 4 and the insert 3 it contains.

[0128] Advantageously, distributing the gaseous fluid 82 onto the surface portion 47 of the first annular chamber 15 allows the gaseous fluid 82 to contact the first annular chamber 15. Thus, the gaseous fluid 82 is cooled by contact with the surface 47 of the first annular chamber 15 in which the liquid 80 flows.

[0129] According to one aspect of the invention, the inlet opening 461 of the outlet branch 46 for the gaseous fluid 82 is configured to convey the gaseous fluid 82 onto the surface portion 48 of the second annular chamber 16 facing the compartment 4 .

[0130] The outlet branch 46 has an opening 19 which is configured to convey the gaseous fluid 82 towards the surface portion 48 of the second annular chamber 16 .

[0131] Advantageously, delivering the gaseous fluid 82 onto the surface portion 48 of the second annular chamber 16 allows the gaseous fluid 82 to contact the second annular chamber 16. Thus, the gaseous fluid 82 is cooled by contact with the surface 48 of the second annular chamber 16 in which the liquid 80 flows.

[0132] According to one aspect, the inlet branch 45 and the outlet branch 46 comprise elements 84 for conveying the gaseous fluid 82 configured to facilitate contact between the gaseous fluid 82 and the surface portions 47 , 48 of the first annular chamber 15 and the second annular chamber 16 , respectively.

[0133] The branch 46 for the gaseous fluid 82 has a gap 490 configured to convey the gaseous fluid 82 over the inner surface 49 of a portion of the end element 12 designed to form the tapered portion 102 of the first end 110 of the tube 100 .

[0134] In other words, the outlet branch 46 is configured to allow the gaseous fluid 82 to contact the inner surface 49 of the end element 12 through the gap 490 .

[0135] Advantageously, the gaseous fluid 82 contacting the inner surface 49 of the end element 12 allows cooling thereof.

[0136] The outlet opening 28 of the outlet branch 46 for the gaseous fluid 82 is positioned on an end wall 120 of the end element 12 perpendicular to the main axis X of the longitudinal extension of the body 10 .

[0137] Advantageously, the outlet opening 28 located on the end wall 120 of the end element 12 allows the gaseous fluid 82 to contact as much of the surface 49 of the end element 12 as possible, thereby maximizing cooling of the end element.

[0138] It should be noted that, advantageously, an embodiment of the liner 1 comprises a plurality of conduits 230 for conveying the liquid 80, in particular a plurality of conduits for the annular chambers 15, 16, as well as an inlet branch 45 and an outlet branch 46 for conveying a gaseous fluid 82 for contacting the annular chambers 15, 16, essentially in all the parts constituting the liner 1, allowing for optimized cooling of the liner 1.

[0139] Basically, as described above, the cooling system 23 is configured to circulate the gaseous fluid 82 inside the liner 1 so that it contacts: the surface portion 47 of the first annular chamber 15, the surface of the insert 3 inside the compartment 4, the surface portion 48 of the second annular chamber 16 and the inner surface 49 of the portion of the end element 12. Thus, the gaseous fluid 82 cools the insert 3 and the end element 12 previously contacted with the first annular chamber 15 and the second annular chamber 16, respectively. The liner 1 includes a heat exchanger system inside it in order to cool the gaseous fluid 82 before it cools the elements of the liner 1, in particular the insert 3 and the end element 12.

[0140] Advantageously, the cooling system 23 of the pad 1 makes it possible to optimize, even out and accelerate the cooling of the pad 1 .

[0141] Optimizing and accelerating uniform cooling of the liner 1 can increase productivity.

[0142] The invention also defines a belling machine 200 for pipes 100 made of thermoplastic material, in particular PVC-U, each having a first end 110 intended to be formed in the form of a bellows 101 .

[0143] The belling machine 200 comprises a belling station 202 which comprises a liner 1 .

[0144] According to one embodiment, the belling machine 200 includes a belling forming unit 20 configured to realize a fluid pressure action on the outer wall of the pipe 100 toward the side surface 2 of the main body 10 of the liner 1 and form it into the shape of the belled portion 101, such as Figure 4B as shown in .

[0145] More specifically, the forming unit 20 forms a sealed container of pressurized air having a function of molding the heated and softened end of the tube 100 against the side surface 2 of the gasket 1 to form the flared portion 101 .

[0146] The flaring forming unit 20 comprises a forming chamber 43, a plurality of clamps 58 for locking the pipe 100, a half flange 59 applied to the locking clamps 58 and a flange 67 movable relative to the gasket 1 and telescopically connected to the forming chamber 43 by means of a compression spring.

[0147] The shaped chamber 43 comprises an elastomeric gasket 57 adhered to the outer wall of the tube 100 and, at the front, to the flat surface of the half-flange 59 .

[0148] According to the present invention, the expanding machine 200 comprises a cooling chamber 203 configured to cool the first end 110 of the tube 100 and to at least partially accommodate the forming pad 1 inside thereof.

[0149] The belling machine 200 comprises means 25 for distributing a fluid 81 comprising a gaseous portion 82 and a liquid portion 83 in a cooling chamber 203 configured to distribute the fluid 81 onto a first end 110 of a tube 100 at least partially engaged by a forming pad 1 .

[0150] More specifically, the distribution device 25 distributes the convective cooling flow to the outside of the flared portion 101 of the tube 100 .

[0151] According to a preferred embodiment, the distribution device 25 comprises a plurality of nozzles configured to diffuse the fluid 81 comprising the gaseous portion 82 and the liquid portion 83 over the first end 110 of the tube 100 formed as the flared portion 101 to optimize the convective cooling of the flared portion.

[0152] Preferably, the dispensing device 25 is fixed to the flange 67 .

[0153] refer to Figure 5 In the most advanced prior art configuration, as shown in document EP2189268, convection for cooling the outside of the flared portion is achieved by a fluid 81 of compressed air 82 and finely atomized water 83.

[0154] The belling machine 200 includes a passage 24 for introducing a fluid 81 pre-cooled by a known external device into the cooling chamber 203 .

[0155] According to the invention, the expanding station 202 comprises a duct 26 for discharging a fluid 81 comprising a gaseous portion 82 and a liquid portion 83 flowing out of the cooling chamber 203 .

[0156] In other words, the flow of the liquid 81 is discharged from the cooling chamber 203 through the discharge channel 26 after impacting and cooling the flared portion 101 .

[0157] According to the present invention, the expanding station 202 comprises a separator 205 which is configured to separate a gaseous portion 82 and a liquid portion 83 from the fluid 81 flowing out of the cooling chamber 203 .

[0158] The discharge conduit 26 is configured to convey the fluid 81 including the gaseous portion 82 and the liquid portion 83 toward the separator 205 .

[0159] The separated liquid portion 83 is discharged to the outside of the expanding station 202 by known means.

[0160] It should be noted that, as is well known, the gas portion 82 also remains moist after the action of the separator 205.

[0161] According to the invention, the expanding station 202 comprises a source 204 of a gaseous fluid 82 under pressure which is in fluid communication with an inlet opening 451 of an inlet branch 45 for the gaseous fluid 82 of the forming pad 1 .

[0162] According to one aspect of the invention, the separator 205 is in fluid communication with the source 204 of pressurized gaseous fluid 82 and is configured to supply the gaseous portion 82 of the fluid 81 to the source 204 of pressurized gaseous fluid 82 .

[0163] According to one aspect of the invention, belling machine 200 comprises an inlet conduit 27 extending between a source 204 of pressurized gaseous fluid 82 and an inlet branch 45 of the gaseous fluid 82 in liner 1 .

[0164] Preferably, the inlet duct 27 extends adjacent to the surface of the first annular chamber 15 .

[0165] More specifically, the belling machine 200 is configured to deliver the still wet and cold gaseous fluid 82 into the liner 1 through the inlet pipe 27. According to the above-described embodiment of the liner 1, the wet gaseous fluid 82 passes through the interior of the liner 1 and is introduced into the external environment through the outlet opening 28 located on the end wall 120 of the end element 12.

[0166] Advantageously, the belling machine 200 can recover at least part of the convective cooling flow which has externally cooled the belled portion 101 , ie it can recover at least part of the fluid 81 .

[0167] It should be noted that, as described above, this embodiment is not exclusive and source 204 may introduce gaseous fluid 82 into liner 1 through inlet opening 451 even without partially or completely recovering gaseous fluid 82 from fluid 81 used to cool the exterior of flared portion 101 .

[0168] According to a preferred embodiment, the flaring station 202 comprises a pair of forming pads 1 for simultaneously flaring two tubes 100 at a time, thereby defining a double flaring mode of operation.

[0169] This embodiment can be configured in a first configuration and a second configuration.

[0170] The first configuration comprises a single cooling chamber 203 and / or forming chamber 43 which at least partially accommodates two forming pads 1 .

[0171] The second configuration comprises two cooling chambers 203 and / or forming chambers 43, each chamber at least partially accommodating a forming pad 1 .

[0172] In both configurations, the gaskets 1 are positioned parallel to each other, defining a center-to-center distance D between the two gaskets 1. It is convenient to set the center-to-center value D as small as possible. In fact, the larger the center-to-center distance D, the larger the transverse dimensions of the belling machine 200 and the dimensions of the belling equipment, resulting in a longer time required to move the pipe 100 from one work station to another, as well as a longer time required to move the belling device.

[0173] In a first configuration, with a separate cooling chamber 203, the minimum value of D is determined by the obvious need to avoid contact between the two flared portions 101 and / or the size of the mechanical pad 1, but also by the need not to adversely affect the cooling uniformity. In fact, the convective cooling flow from the distribution device 25 of the cooling chamber 203 is different from the convective cooling flow occurring in the relative lateral areas of the two flared portions 101 formed relative to each other, and its intensity is less than the convective cooling flow occurring in the relative lateral areas of the two flared portions 101 formed relative to each other. In other words, the two flared portions 101 are shielded from each other with respect to the convection distributed by the distribution device 25. The greater the value of D, the smaller the negative impact of the cooling non-uniformity. With the increase of the value of D, the size of the cooling chamber 203 also increases with the increase of the time required for its pressurization and decompression and the increase of the pressurized air consumption. The pad 1 for a specific cooling system 23 in a pad 1 with liquid 80 reduces the above-mentioned negative impact.

[0174] In the second configuration with two cooling chambers 203, since each gasket 1 is accommodated in its own cooling chamber 203, there is no uneven cooling of the flared portions 101 caused by mutual shielding of the convection of the two flared portions 101. In this configuration, uneven cooling of the flared portions 101 exists in any case because it is technically difficult to divide the convection of the fluid 81 in the two cooling chambers 203 equally. The gasket 1 for the specific cooling system 23 inside the gasket 1 with the liquid 80 reduces the above negative impact. On the other hand, in the second configuration, the minimum value D that can be achieved is equal to the lateral dimension of the forming chamber 43 and / or the cooling chamber 203 and the mechanical gasket 1 assembly, which can be obtained by arranging the cooling chambers 203 adjacent to and parallel to each other, as Fig.10 shown in

[0175] Experimentally, in order to obtain the advantages of economic output and higher productivity, compared with single flaring, higher productivity can be achieved through double flaring processing. It has been evaluated that when producing PVC-U sewer pipe fittings 100 with flared portions 101 having a sealing seat portion, where "de" is the value of the outer diameter of the fitting to be processed in mm, "s" is the value of the wall thickness of the fitting in mm, and the center-to-center distance D in mm must meet the condition D < Dl, where

[0176] Dl = [2 + f]de, where f = [2.125 - 0.0416(de / s)].

[0177] This means that the value of the center-to-center distance D in mm must meet the condition:

[0178] D < [4.125 - 0.416(de / s)]de.

[0179] Due to the characteristics of the mechanical gasket 1 according to the present invention, especially the characteristics of the specific internal cooling system 23 of the gasket 1 and the lateral dimension of the gasket 1, which is always equal to or not greater than the dimension in the mechanical gasket of the prior art, in both the first configuration and the second configuration, the condition D < Dl is generally satisfied. Specifically, in the second configuration, it is convenient to use the value of the lateral dimension of the assembly composed of the forming chamber 43 and / or the cooling chamber 203 and the mechanical gasket 1 as the D value, as Fig.10 shown in

[0180] Regarding the production capacity of the flaring machine 200, the consumption of compressed air for forming, and the consumption of the liquid 80 for cooling outside the flaring machine 110, the second configuration has an advantage over the first configuration because it allows the dimensions of the cooling chambers 203 such that the total internal volume of the two cooling chambers 203 in the second configuration is less than the total internal volume in the single cooling chamber 203 according to the first configuration.

[0181] In short, this embodiment of the belling machine 200 allows two liners 1 to be cooled simultaneously as if they were a single piece, thereby speeding up the process of making the belled portion 101 .

[0182] The simultaneous cooling of the two liners 1 allows an increase in productivity, since it potentially allows twice as many pipes 100 to be processed in the same period of time.

[0183] These advantages are even more pronounced in the case of short tubes 100. In fact, the extrusion of the tube 100 made of thermoplastic material takes place at a predetermined extrusion speed, so cutting a short tube 100 requires machining more pieces than any longer tube 100 cut at the same speed from the extruded tube 100. Accelerated cooling means the possibility of not reducing the extrusion speed, thus keeping the productivity at an optimal level.

[0184] According to one embodiment, the source 204 of gaseous fluid 82 under pressure is in fluid communication with the inlet opening 451 of the inlet branch 45 for gaseous fluid 82 of the respective forming pad 1 .

[0185] In other words, the source 204 of gaseous fluid under pressure 82 is the same for both pads 1 .

[0186] According to one embodiment, the discharge conduit 26 of each cooling chamber 203 is configured to convey the fluid 81 including the gaseous portion 82 and the liquid portion 83 towards the same separator 205 .

[0187] In other words, the separator 205 is identical for both pads 1 .

[0188] According to a preferred embodiment, the belling machine 200 comprises one or more heating stations 201, which are positioned upstream of a separate belling station 202 according to the feed direction V, for processing the pipe 100, such as Fig.11 as shown in .

[0189] Each heating station 201 includes a separate oven 206 configured to heat the ends 110 of a pair of tubes 100 .

[0190] In other words, the expanding machine 200 has a separate oven 206 in the heating station for the two ends 110 of the two pipes 100 .

[0191] Below is described example embodiments of the formed liner 1. These examples relate to a liner 1 intended to form an end flare with a gasket seat in a PVC-U sewer pipe having an outer diameter of 110 mm and a nominal wall thickness of 3.2 mm.

[0192] Preferably, the gasket 1 is a mechanical gasket.

[0193] according to Figures 6A to 6F In the embodiment shown in , the means 5 for moving the inserter 3 comprise a wedge-shaped mechanism 50 .

[0194] Fig. 8A and 8B The liner 1 is shown with a wedge 50 positioned within a forming cavity 43, the dimensions of which are optimized and specific to the dimensions of the tube 100 to be expanded.

[0195] In the pad 1 with the wedge 50, the bearing shaft 6 has a cylindrical rod shape and is configured to support the body 10, the wedge 50 and the insert 3. The bearing shaft 6 is also a guide for the wedge 50 to slide.

[0196] The wedge 50 comprises a pair of sliding bushings 51 which engage in the carrier shaft 6 .

[0197] In short, the device 5 for moving the insert 3 in the pad 1 shaped as a wedge 50 consists of a wedge-shaped element 50 and a bushing 51 .

[0198] The pad 1 comprises a socket 60 screwed to the rear portion 7 of the body 10 , a plunger 62 of the socket 60 and a pair of rods 61 passing through the rear portion 7 of the body 10 , the rods 61 rigidly connecting the wedge 50 to the plungers 62 .

[0199] The socket 60 is a linear actuator that controls the translational movement of the wedge 50 that moves the insert 3 between the retracted position P1 and the deployed position P2 .

[0200] The stroke of the jack 60 corresponds to the operating stroke of the wedge 50. Figure 6C Marked as C.

[0201] The two rods 61 are configured to prevent the wedge 50 from rotating about the bearing shaft 6 , thereby preventing the wedge 50 from rotating and the insert 3 from rotating about the axis X.

[0202] According to an exemplary embodiment of the pad 1 shaped as a wedge 50, the bearing shaft 6 is solid and has an outer diameter measuring 20 mm. The delivery duct 32 and the return duct 35 allowing communication between the rear portion 7 and the front portion 8 of the body 10 during the circulation of the liquid 80 are made as parallel through holes symmetrical with respect to the axis X, with a diameter of 5 mm. The ends of these holes are closed with covers 17 equipped with rubber sealing elements.

[0203] The conveying line 32 is intercepted by a first transverse channel 37 and a second transverse channel 38 .

[0204] The return line 35 is intercepted by a third transverse channel 39 and a fourth transverse channel 40 .

[0205] The delivery duct 32 and the return duct 35 form a passage portion sufficient to maintain a minimum flow rate of the liquid 80 circulating in the gasket 1 in the order of 6-8 lit / min. This flow rate can be maintained by a conventional industrial cooler and is sufficient to achieve the effect of reducing the step time of cooling the flared portion 101, which allows the productivity of the flaring machine 200 to be increased by more than 15% for PVC-U sewage pipe fittings with an outer diameter of 110 mm and a nominal wall thickness of 3.2 mm, compared to conventional air-cooled mechanical gaskets. With the insert 3 in the retracted position P1, the first annular chamber 15 extends beyond the position reached by the larger base of the wedge 50, and the longitudinal length value Lc of the rear chamber is greater than the operating stroke C in the wedge 50. This configuration increases the heat exchange surface and thus increases the cooling intensity of the flared portion 101.

[0206] The expanding machine 200 comprises a liner 1 with a wedge 50, comprising an electromechanical device configured to send a position signal of the sector 3 to an electrical control unit of the expanding machine 200. This device is located directly in the socket 60 and is used to actuate the wedge 50 by means of sensors applied to the sheath of the socket 60. These sensors can be activated by a magnetic ring integrated in the plunger 62.

[0207] In the example shown in the figures, the device is applied to the outside of the support of the socket 60 by means of a metal pin 52 with a mushroom-shaped head, the axis of which preferably coincides with the axis X of the pad 1. The pin 52 is slidable in the axial direction and is held in the rest position by the axial contact achieved by the compression spring 53. At the end opposite the mushroom-shaped head, the pin 52 is connected to a metal element 63 outside the socket 60. In the rest position, the head of the mushroom-shaped pin 52 is located in a chamber 64 of the socket 60. In the case of the rear end of the stroke position of the plunger 62, the pin 52 performs an axial movement so that the metal element 63 activates the proximity sensor 54 outside the socket 60. The proximity sensor 54 signals the retracted position P1 of the insert 3 to the electrical command and control unit of the expanding machine 200. In the case of the front end of the stroke position of the plunger 62, the pin 52 returns to the rest position by means of the compression spring 53 and the proximity sensor 54 is deactivated, signaling the state of the insert 3 in the deployed position P2.

[0208] according to Figures 7A to 7G In the embodiment shown in , the means 5 for moving the inserter 3 comprise a cam mechanism 55 .

[0209] Fig. 9 A liner 1 is shown with a cam 55 integral with a flange 68 fixed to the liner. The liner 1 is positioned within a forming chamber 69. The forming chamber 69 is intended to operate with liners of different sizes, i.e. liners for flaring pipes of different sizes and greater than an outer diameter of 110 mm.

[0210] The bearing shaft 6 is hollow in the pad 1 with the cam 55. In this cavity, the axis of the cam 70 is coaxial with the bearing shaft 6.

[0211] The pad 1 comprises two annular elements, namely a rear element 71 and a front element 72 , opposite each other relative to the compartment 4 , and a key 56 configured to connect the shaft of the cam 70 to the annular elements 71 and 72 .

[0212] The annular elements 71 and 72 are essentially flanges which are mirror-symmetrical with respect to the insert 3 .

[0213] The elements 71 and 72 have the same longitudinal dimension B and the cam 55 is made of these elements. Thus, the rotation of the shaft of the cam 70 , by means of the key 56 , performs a rotational movement of the annular elements 71 and 72 and thus a radial translational movement of the insert 3 .

[0214] The pair of cams 55 formed in the ring members 71 and 72 have the same shape and size but are opposed to each other.

[0215] In short, the device 5 for moving the insert 3 in the pad 1 with the cam 55 comprises the annular elements 71 and 72 of the cam 55 and the key 56 .

[0216] The pad 1 comprises an actuator 65 , preferably mounted and already integrated in the belling machine 200 , configured for controlling the rotation of the shaft of the cam 70 .

[0217] The actuator 65 includes a coupling 66 by which the actuator 65 is connected to the shaft of the cam 70 .

[0218] More specifically, unlike the pad 1 with wedge 50 , the pad 1 with cam 55 engages a common actuator 65 for moving the insert 3 already present in the expanding machine 200 .

[0219] According to an exemplary embodiment of a gasket 1 with a gasket 55, the gasket 1 is again intended for forming an end flared portion 101 with a gasket seat in a PVC-U sewer pipe fitting having an outer diameter of 110 mm, a nominal wall thickness of 3.2 mm, and an outer diameter of a bearing shaft 6 of 42 mm. The diameter of the cavity is 19 mm. The delivery duct 32 and the return duct 35 allowing communication between the rear portion 7 and the front portion 8 of the body 10 are made in the outermost area of ​​the bearing shaft 6 and are made as through holes parallel to the X axis and symmetrical with respect to the axis X, with a diameter of 5 mm. The ends of these holes are closed with threaded caps 17 with airtight seals.

[0220] The conveying line 32 is intercepted by a first transverse channel 37 and a second transverse channel 38 .

[0221] The return line 35 is intercepted by a third transverse channel 39 and a fourth transverse channel 40 .

[0222] The delivery duct 32 and the return duct 35 form a passage portion sufficient to maintain a minimum flow rate of the liquid 80 circulating in the liner 1 in the order of 6-8 lit / min. This flow rate can be maintained by a conventional industrial chiller and is sufficient to achieve the effect of reducing the step time of cooling the flared portion 101, which allows the productivity of the flaring machine 200 to be increased by more than 15% for PVC-U sewer pipe fittings with an outer diameter of 110 mm and a nominal wall thickness of 3.2 mm, compared to conventional air-cooled mechanical linings.

[0223] The first annular chamber 15 extends beyond the position of the element 71 , the longitudinal length Lc of the rear chamber having a value greater than the longitudinal extension B of the element 71 . This configuration increases the heat exchange surface and thus the cooling intensity of the flared portion 101 .

[0224] It should be noted that the outer surfaces of the annular elements 71 and 72 are shaped so as to perform the function of a conveying portion 84 for a gaseous fluid 82 intended to contact the surfaces of the first and second annular chambers 15 and 16 .

[0225] The expanding machine 200 comprises a liner 1 with wedges 55, comprising an electromechanical device configured to send a position signal of the sectors 3 to the electrical command and control unit of the expanding machine 200. In order not to make the best internal embodiment of the liner 1 for internal cooling of the liner 1, the device is made outside the body 10 of the liner 1.

[0226] It should be noted that in the liner 1 according to the invention, as in the exemplary embodiment, the shape and size of the outer surface 2 of the liner 1 (including the insertion hole 60 in the case where the liner 1 has a wedge 50) are the same as those required for conventional mechanical liners, and in particular the radial dimensions are not greater than those of conventional mechanical liners. According to the exemplary embodiment, the system for fixing the corresponding conventional liner to the belling machine 200 is maintained. These features that can be obtained by the present invention are advantageous because they make the liner 1 according to the present invention installable and usable in most belling machines 200 present in the production system of PVC-U pipes 100, and also in conventional belling machines already operating on existing extrusion lines.

[0227] In fact, usually, the dedicated belling machine 200 for the mechanical lining 1 processing of the PVC-U pipe 100 is also equipped for processing the smooth lining 1. The smooth lining 1 includes a cooling system 23 inside the lining 1, and the cooling system 23 has a liquid 80. Therefore, the belling machine 200 including the cooling system 23 of the smooth lining 1 can be used together with the same system for belling processing using the mechanical lining 1 according to the present invention.

[0228] An exemplary embodiment of the present invention relates to an apparatus intended to give a flared portion 101 in a PVC-U sewer pipe fitting 100 a minimum dimension of 110 mm for the diameter of a particular sewer pipe fitting 100. The embodiment according to the present invention is undoubtedly easier and more versatile in an apparatus intended to give a flared portion 102 of a sewer pipe fitting 100 with a larger diameter, since it is obvious that the larger the diameter of the fitting 100, the larger the space available in the liner 1 for manufacturing the specific features according to the present invention. In particular, the pipes 32 and 35 in the load-bearing shaft 6 can be composed of more than two pipes or pipes with a larger channel cross section. The structural shape of the pipes 32 and 35 can also be conveniently different from the structural shape of the through-holes made directly in the body of the load-bearing shaft 6, for example they can be rigid pipes or flexible pipes, which can be enclosed in a cavity in the load-bearing shaft 6 in a detachable manner.

[0229] Fig.10 An exemplary embodiment of a belling machine 200 for multiple belling, in particular double belling, is shown, which is configured with two cooling chambers 203 and / or forming chambers 43, each chamber accommodating a forming pad 1. Fig.10 The pad 1 shown in FIG. 1 is a wedge-shaped pad 50, which has been described as an exemplary embodiment and is Fig. 8A and 8B 203. The flaring station 202 comprises two cooling chambers 203 and / or forming chambers 43, one for each pad 1 of a pair of forming pads 1 with a wedge 50. The forming chambers 43 and / or cooling chambers 203 are positioned adjacent to each other and in parallel and define a center-to-center distance D between the two pads 1, the value of which is equal to the size of the cooling chamber 203 and / or forming chamber 43.

[0230] More specifically, according to Fig.10 The embodiment shown in , shall consider an application example, in which the applicant has manufactured a belling machine 200 intended for belling a PVC-U sewer pipe fitting 100 having a diameter of 110 mm, a nominal wall thickness of 3.2 mm, and a center-to-center value D equal to 210 mm. Considering the formula defining the value of Dl, Dl = [2 + [2.125 - 0.0416 (de / s)] de, where "de" = 110 mm and "s" = 3.2 mm, Dl = 296 mm, so this value D satisfies the condition D <Dl。

[0231] Advantageously, the liner 1 internally cooled with liquid 80 allows for more uniform cooling around the flared portion 101 than conventional machine liners. This advantage, coupled with the reduced radial dimensions of the liner 1, facilitates the use of the liner 1 cooled with liquid 80 in multiple flaring operations, whether a single cooling chamber 203 is used for all tubes 100 in a group of multiple flared tubes 100, or multiple cooling chambers 203 are used for each tube 100 in a group of multiple flared tubes 100.

[0232] Advantageously, the pad 1 is cooled from the inside by the circulation of the liquid 80 .

[0233] Advantageously, the flow of gaseous fluid 82 intended for cooling the insert 3 and the end element 12 is cooled by the liquid 80 by means of the metal surface which is itself cooled by the liquid 80 circulating in the body 10 of the gasket 1 .

[0234] Advantageously, the convective cooling of the insert 3 and the end element 12 using the gaseous fluid 82 is intensive and uniform.

[0235] Advantageously, the cooling system 23 within the liner 1 with the liquid 80 allows the liner 1 to remain within the radial dimension limitations of conventional mechanical liners.

[0236] Advantageously, the cooling system 23 inside the liner 1 with the liquid 80 according to the invention allows the liner 1 to be manufactured according to requirements interchangeable with traditional mechanical liners, thus allowing adaptability and possibility of installation in traditional belling machines.

[0237] Advantageously, the liner 1 according to the invention increases the productivity of a belling machine for manufacturing the belled portion 101 with a mechanical lining system.

[0238] Advantageously, the liner 1 according to the invention allows the production of belling machines for mechanical liner systems having multiple belling configurations.

[0239] Advantageously, the liner 1 according to the invention and the expanding machine 200 according to the invention improve the cooling energy efficiency in the expanding of mechanical liner, in particular reduce the consumption of compressed air for cooling the expanded portion 101 .

[0240] These advantages can be quantified in the non-limiting example of a production plan described below.

[0241] The PVC-U pipe fitting 100 to be expanded with the mechanical gasket is a pipe fitting 100 having an outer diameter of 110 mm and an actual wall thickness of 3.5 mm.

[0242] The time tb of the expansion cycle is given by the sum of the three contributions: tb = tm + tf + tr, where:

[0243] tm = movement time of pipe fittings and flaring equipment

[0244] tf = minimum time required to form the end of the pipe in the liner

[0245] tr = cooling time of the flared portion formed in the liner.

[0246] Generally speaking, the following conditions apply:

[0247] - Since the movement stroke of the pipe 100 in the belling machine 200 is longer, tm is longer in double belling;

[0248] - tf is adjusted by the material, the shape of the flared portion 101 and the volume of the forming chamber 43, in particular by the volume to be pressurized;

[0249] When cooling the pad 1 with liquid 80 is used, tr is shorter.

[0250] For conventional mechanical liners with internal cooling by air and separate flares: tb = tm + tf + tr = 6 + 3 + 6 = 15 seconds (production speed OS = 240 flares / hour, compressed air consumption per flare = 280 Nl).

[0251] For mechanical linings with liquid and separate flare internal cooling: tb = tm + tf + tr = 6 + 3 + 3 = 12 seconds (OS = 300 flares / hour, compressed air consumption per flare = 150 Nl / cycle).

[0252] For mechanical lining with liquid and double flare internal cooling: tb = tm + tf + tr = 9 + 4 + 3 = 16 seconds (OS = 225 x 2 = 450 flares / hour, compressed air consumption per flare = 150 Nl / cycle).

Claims

1. A gasket for forming an end flared portion in a pipe (100) made of thermoplastic material, in particular PVC-U, each of the pipes having a first end (110) designed to be flared (101); the gasket (1) include: a body (10) configured to at least partially fit the first end (110) of the pipe (100) and having a longitudinally extending main axis (X); The body (10) comprises a front portion (8) and a rear portion (7), the front portion (8) having at least one end element (12), the end element (12) being designed to form a tapered portion (102) of the first end (110) of the tube (100); The body (10) has a compartment (4) designed to accommodate a plurality of inserts (3) and means (5) for moving the inserts (3), the means (5) being configured to move the inserts (3) between a retracted position (P1) in which they are positioned inside the compartment (4) and an extended position (P2) in which at least a portion of the inserts (3) are positioned outside the compartment (4); The insert (3) is inserted between the front portion (8) and the rear portion (7) of the body (10); The body (10) comprises a bearing shaft (6) supporting the body (10) and at least means (5) for moving the insert (3), the means (5) extending parallel to the main axis (X) extending longitudinally; The forming pad (1) comprises a system (23) for cooling the body (10), the cooling system (23) comprising a plurality of ducts (230) for conveying a liquid (80), the ducts (230) comprising at least a first annular chamber (15) formed in the rear portion (7) of the body (10) and a second annular chamber (16) formed in the front portion (8) of the body (10); the first annular chamber (15) and the second annular chamber (16) extending at least partially around the main axis (X) of the longitudinal extension of the body (10), The gasket is characterized in that the pipe (230) for conveying the liquid (80) includes at least a conveying pipe (32) and a return pipe (35) within the bearing shaft (6), and has a main extension direction parallel to the main axis (X) extending longitudinally of the main body (10); the conveying pipe (32) is fluidically connected to the first annular chamber (15) and the second annular chamber (16), and the return pipe (35) is fluidically connected to the second annular chamber (16).

2. A pad according to the preceding claim, It is characterized in that The conduit (230) for conveying the liquid (80) comprises an inlet opening (21) for the liquid (80) for fluid communication with the first annular chamber (15) and an outlet opening (22) for the liquid (80) for fluid communication with the second annular chamber (16).

3. A pad according to the preceding claim, It is characterized in that The inlet opening (21) and the outlet opening (22) for the liquid (80) are located in the rear portion (7) of the body (10).

4. The pad according to claim 2 or 3, It is characterized in that The pipeline (230) for conveying the liquid (80) comprises: a first passage (30) extending from the inlet opening (21) of the liquid (80) to the first annular chamber (15); a second passage (31), the second passage extending from the first annular chamber (15) to the delivery pipe (32); a third passage (33), the third passage extending from the delivery pipe (32) to the second annular chamber (16); a fourth passage (34), the fourth passage extending from the second annular chamber (16) to the return pipe (35); A fifth channel (36) extends from the return conduit (35) to the outlet opening (22) for the liquid (80).

5. A pad according to the preceding claim, It is characterized in that The first annular chamber (15) has a first hole (41), which is configured to connect the first annular chamber (15) with the second channel (31) fluidically, and the second annular chamber (16) has a second hole (42), which is configured to connect the second annular chamber (16) with the fourth channel (34) fluidically.

6. The pad according to claim 4 or 5, It is characterized in that The pipeline (230) for conveying the liquid (80) comprises: a first transverse channel (37) configured to connect the second channel (31) to the delivery conduit (32) in fluid communication; a second transverse passage (38) configured to connect the delivery conduit (32) to the third passage (33) in fluid communication; a third transverse channel (39) configured to connect the fourth channel (34) to the return conduit (35) in fluid communication; a fourth transverse channel (40) configured to connect the return conduit (35) to the fifth channel (36) in fluid communication, The first transverse channel (37), the second transverse channel (38), the third transverse channel (39) and the fourth transverse channel (40) are positioned in the bearing shaft (6) and have a main extension direction transverse to the main axis (X) of longitudinal extension.

7. A pad according to any one of the preceding claims, It is characterized in that The delivery duct (32) and the return duct (35) are longitudinal through holes formed directly in the body of the bearing shaft (6).

8. A gasket according to the preceding claim, comprising a plurality of covers (17), the delivery duct (32) and the return duct (35) comprising respective ends; each end of the delivery duct (32) and the return duct (35) being closed by a respective cover (17).

9. The pad according to any one of claims 1 to 6, It is characterized in that The load-bearing shaft (6) has a cavity, and the delivery pipe (32) and the return pipe (35) are flexible pipes or rigid pipes positioned in the cavity of the load-bearing shaft (6).

10. A pad according to any one of the preceding claims, It is characterized in that The means (5) for moving the insert (3) comprises a cam mechanism (55).

11. The pad according to any one of claims 1 to 9, It is characterized in that The means (5) for moving the insert (3) comprises a wedge mechanism (50).

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