BACKGROUND OF THE INVENTION Flared pipes/tubes are usually used in cases where a relatively precise connection is needed between a pipe and a connector. For instance, it is required to make such connection securely in cases where high-pressure fluid transfer from the pipe to the connector part is needed. Otherwise, there may arise a leak in the pipe to connector connection, and it will not be possible to transfer the liquid to the connector at desired pressure.

The connector comprises a conical housing for the flared pipe connection, and after the conical surface of the flared head is seated on the conical housing in the connector, it is secured via a connecting means. The connecting means is generally a threaded sleeve, and the connection is fixed by the engagement of the threads of the sleeve with threads formed on the connector.

There are two main aspects taken into consideration in flared pipe connections: The axial force applied to the flared head by the connecting means is required to be within a certain range, and the torsion stress occurring on the flared pipe by the connecting means should not exceed a certain limit. If the axial force applied by the connecting means on the flared head exceeds a certain limit, the flared head undertakes more plastic deformation than necessary and the coupling balance between the tapering of the flared head and the housing in the connector fails. In case the axial force is lower than a certain amount, the necessary plastic deformation on the flared head will not form and coupling balance between the flared pipe and the connector will not occur. In such a case, the l flared head cannot be positioned precisely in the slot of the connector, and leakage may take place. On the other hand, if the connecting means is tightened too much, torsion stress on pipe increases and this may cause the connection to loose in time as tension stress forms stored torque in direction of loosening the connection. Furthermore, the loosening risk of the connection due to vibration in time may increase depending on an arrangement where pipe-to-connector connection will be used.

A solution to the above-mentioned problems can be offered by providing different frictions basically at different parts of the connection. For example, such a proposal is made in US 8,172,278 to this problem by applying a coating on the surfaces where connecting means is contacting the connector and flared head, and on the threaded surface. According to US 8,172,278, the coefficient of friction applied to threads of the connecting means is larger than the coefficient of friction of the coating on the other coated surfaces. The proposal in US 8,172,278 is disadvantageous and costly, since it requires applying two different coating on different parts of the connecting means.

BRIEF DESCRIPTION OF THE INVENTION

The object of the present invention is to provide an effective flared pipe for piping connections.

Another object of the invention is to provide an effective flared pipe connection arrangement. According to the above objects, the present invention relates to a pipe comprising a flare arranged at at least one end of the pipe, the flare extending outwardly from the pipe wall and having an upper surface close to the pipe wall and a lower conical surface below the upper surface, wherein the upper surface of the flare is at least partially coated with a coating material. According to a preferred embodiment of the invention, the external surface of the pipe remaining slightly above the flare is coated at least partially with the coating material in addition to the upper surface of the flare. According to the preferred embodiment of the invention, the coefficient of friction of the coating material is lower than coefficient of friction of the lower conical surface.

The invention, in a further aspect, relates to a pipe connection arrangement. The connection arrangement comprises a pipe comprising a flare at least at one end of the pipe, the flare extending outwardly from the pipe wall and having an at least partially coated upper surface close to the pipe wall and a lower conical surface below the upper surface; a connector comprising a conical housing having a form for supporting the lower conical surface; a threaded connecting means forcing the upper surface of the flare for connecting the pipe to the connector and the threaded connecting means having threads engaging to threads threaded formed on the connector.

According to a preferred embodiment of the invention, the threads of the threaded connecting means are at least partially coated with a coating material. According to the preferred embodiment of the invention, the coefficient of friction of the material, with which are the threads coated, is higher than the coefficient of friction the material, with which the upper surface of the flare is coated.

According to one embodiment of the invention, both the threads of the threaded connecting means and the surface of the threaded connecting means forcing the upper surface of the flare are coated with a coating material. BRIEF DESCRIPTION OF THE FIGURES

In order to better understand the configuration of the present invention and its advantages with additional elements, it is necessary to evaluate it along with the figures that are described below.

Figure 1 is the side of view of the flared pipe according to the invention.

Figure 2 is the sectional side of view of the pipe connection arrangement according to the invention.

Figure 3 is another sectional side of view of the pipe connection arrangement according to the invention. DETAILED DESCRIPTION OF THE INVENTION

As it is seen in Figure 1, the flared pipe (1) according to the invention comprises a flare (2) extending outwardly from the pipe wall (1.1) on at least one end of the pipe (1). The flare (2) has preferably a circular form and comprises an upper surface (3) close to the pipe wall (1.1) and a lower conical surface (4) formed below the upper surface (3). The flare (2) is preferably monolithic with the pipe (1) and formed on the far end of the pipe (1) by undergoing plastic deformation.

The flare (2) can have various forms. For example, the upper surface (4) can have an angle 22.5° to 135° with the pipe axis. Therefore, a connection element can find a sufficient space to be located onto the flare upper surface (3). For example, in Figure 1, the angle between the upper surface (3) and the pipe axis is 90°.

The lower conical surface (4) is also formed so that it can have a various tapering angles. According to the preferred embodiment of the invention, tapering angle of the flare lower surface (3) may vary from 22.5° to 135°, and it has a tapering angle of 115° in male flares, and 90° or 120° in female flares. These angles are amounted with reference to the axial line of the pipe.

Flare upper surface (3) is at least partially coated with a coating material. After coating is applied, the coefficient of friction of the flare upper surface (3) preferably has a value between 0.03 - 0.08. The coefficient of friction of the flare lower surface (4) is higher than that of the upper surface in any case, and is 2 to 5 times more than the latter.

According to the preferred embodiment of the invention, the thickness of coating is between 5μ-20μ, more preferably between 7μ-15μ. Molybdenum disulfide (MoS ₂ ) is used as the coating material, and optionally, molybdenum disulfide polytetrafluoroethylene (PTFE) can be admixed.

The coating can be applied on the flare upper surface (3) in several ways, such as spraying or dipping as known in the art. Yet, necessary precautions are taken for avoiding the coating of the flare lower surface (4) while coating is made; for example, the coating can be made by covering the lower conical surface (4) via a mask. The lower conical surface (4) should not be coated since it will be positioned precisely in a conical housing to be seated on the connector where the pipe connection is to be applied.

According to one embodiment of the invention, area where coating is to be applied can also include the external surface (5) of the pipe wall slightly above the flare (2). Therefore, the coating is applied both onto the flare upper surface and the external surface slightly above the upper surface, which would be advantageous. Likewise, as a connection element (for example a sleeve) applies force in axial direction on the flare upper surface for the attachment of the pipe to a connector provides a better friction, the coating on the pipe wall just above the flare may provide that this friction happens at a greater extent. Likewise, the coating layer on the pipe wall may contact to the cylindrical inner surface of the connecting means.

The invention relates, in a further aspect, to pipe connection arrangement. Example of such an arrangement is shown in figure 3, and the arrangement comprises a flared pipe (1) with the flare upper surface (3) coated. In addition, it comprises a connector (6), which the pipe (1) can be connected to, and a connecting means (10) for the fixation of the pipe-to-connector connection. Such a pipe connection arrangement may be suitable for the transfer of a pressurized liquid passing through the pipe (1) into an opening (8) formed on the connector. Such an arrangement can be used for example in motor vehicles (for example in hydraulic brake system of motor vehicles).

The pipe (1) is connected to the connector (6) on the end where the flare (2) is formed. The connector (6) comprises a conical housing (7), and the flare lower surface (4) of the pipe in conical form is seated on the connector conical housing (7). Thereafter, the pipe

(I) that is provided through a bore (13) formed along a connecting means (10) is fixed to the connector (6) by screwing the connecting means (10), such as a sleeve, having threads formed at its cylindrical body surface. In order to achieve a connection, the tip (11) of the connecting means applies pushing force on the upper side of the flare upper surface (3). The threads (12) formed on the body (14) of the connecting means (10) are formed the way that they engage to threads (9) formed on the inner walls of an opening (15) formed along the connector (6).

The connecting means (10) is preferably completely coated by an anti-corrosion material comprising zinc-nickel. Forcing the flare upper surface (3) is the circular end (11) of the connecting means (10) and the tip (11) of the connecting means can be coated with a coating material via a known coating method (by dipping or spraying etc.). The coefficient of friction of the material used in coating the tip (11) of the connecting means is lower than the coefficient of friction of the material used in coating all the surfaces of the connecting means (10). According to the preferred embodiment of the invention, the tip

(II) of the connecting means (10) has a coefficient of friction of 0.03 to 0.07 after being coated. As the coating material, molybdenum disulfide (MoS2) is used, and optionally, molybdenum disulfide polytetrafluoroethylene (PTFE) can be admixed thereto. According to the preferred embodiment of the invention, the coating thickness of the tip (11) of the connecting means is 5μ to 20μ. The connecting means threads (12) may be preferably coated (dipping, spraying etc.) with a coating having a higher coefficient of friction. When threads (12) are coated, the coefficient of friction of threads is higher than the coefficient of friction of the other surfaces of the connecting means (10), the whole of which is coated with another anti- corrosive material (for example zinc-nickel admixture). Furthermore, the coefficient of friction of threads is higher than the coefficient of friction of the coated flare upper surface (3). Similarly, in cases where the tip (11) of the connecting means (11) is coated in addition to the threads (12), the coefficient of friction of the threads is higher than that of the coated tip (11) of the connecting means. According to the preferred embodiment of the invention, the threads of the connecting means (12) have a coating thickness of 15μ to 20μ after being coated.