Pipe processing method, pipe, and pipe connection device

Abstract

A method for treating a pipe (1), particularly an automotive pipe, is characterized by forming a flare (2) on at least one pipe end of the pipe. At least a predetermined area (3, 6) of the flare has at least one layer (4, 7) that changes the frictional properties of the coated surface of the flare. The flare is coated with a plasma coating.

Description

Technical Field

[0001] (Related Application) This disclosure is a PCT application claiming the benefit of European Application No. 20193135.9 filed on Aug. 27, 2020, the entire content of which is incorporated herein by reference.

[0002] This disclosure relates to a method for processing pipes, particularly pipes for motor vehicles. The pipe has a flare formed at at least one pipe end. Further, this disclosure relates to a corresponding pipe and a pipe connection device for connecting the pipes. The flare of the pipe particularly includes an F-type flare or an E-type flare.

Background Art

[0003] Such pipes having a flare at the end are connected to a connection element or a connection block, particularly as pipes for motor vehicles. For example, the pipes are used for hydraulic fluid or brake fluid. For connection to a connection element, the pipe usually passes through the axial hole of a threaded joint, and the end face of the threaded joint acts on the back side of the flare of the pipe. The threaded joint has a male thread and is screwed into a corresponding female thread to be connected to the connection element. When the threaded joint is tightened, usually, the front end of the flare of the pipe is pressed against the sealing surface of the connection element. Usually, the connection element is integrated with an additional pipe located at the same height as the connected pipe. When screwing in the threaded joint, the pipe rotates together, and due to the torsion of the pipe, so to speak, spring force is stored in the pipe. Torsion of the pipe generates a reverse torque, and therefore, loosening or detachment of the screwed connection, which is undesirable or uncontrollable during operation, may occur. Such undesirable loosening of the screwed connection may particularly occur due to vibrations, for example, in the engine compartment of a motor vehicle.

Summary of the Invention

Problems to be Solved by the Invention

[0004] The methods, pipes and pipe connection elements of the types described above are known in various configurations. In order to reduce the above-described drawbacks related to the torsion of the pipe, it is already known to process the flare at the end of the pipe, in particular the rear end of the flare on which the end face of the screwed joint acts. Therefore, it is known that by removing the coating on the flare already applied to the pipe and polishing the corresponding surface of the flare, the friction characteristics are affected. This is intended to reduce the friction between the acting end face of the screwed joint and the rear end of the flare. However, it has been found that such known processes have a number of drawbacks, one of which is that the process becomes relatively complex due to a series of procedures and further increases the cost. Another one is that an undesirable corrosive effect occurs by removing the coating. Furthermore, since the quality of the surface to be processed depends on a number of parameters, the surface cannot be set or adjusted with high reproducibility. As a result, it has been found that the functional reliability of the screwed connection is not necessarily ensured.

Means for Solving the Problems

[0005] In contrast, the present disclosure is based on the above technical problems and easily and effectively avoids the above problems. The present disclosure is further based on the technical problem of providing a corresponding pipe and a corresponding pipe connection device.

[0006] To solve this technical problem, the present disclosure teaches a method for processing a pipe, in particular a pipe for an automobile. In this method, a flare is formed at at least one pipe end of the pipe. At least one layer that changes the friction characteristics of the coated surface of the flare is applied to at least a predetermined region of the flare. The flare is coated by plasma coating. Advantageously, the flare is formed integrally with the pipe at the pipe end or is formed from the pipe.

[0007] The framework of the present disclosure includes that at least a predetermined area of the flared rear end facing the pipe has one layer, i.e., the first layer, by plasma coating. Said layer, i.e., the first layer, has a friction value μ1. Advantageously, one layer, i.e., the first layer, is applied by plasma coating to at least 50%, particularly at least 60%, of the surface of the flared rear end. Furthermore, the framework of the present disclosure includes that this layer, i.e., the first layer, applied by plasma coating has a relatively small friction value or a relatively very small friction value. Thereby, when tightening or screwing in a threaded joint acting on the flared rear end, the torsion of the pipe can be reliably avoided or greatly avoided. In such an embodiment including a threaded joint, advantageously, the end face of the threaded joint has a layer with a small friction value. Said layer is likewise preferably applied by plasma coating. In a preferred embodiment of the present disclosure, the thread or male thread of the threaded joint, in an embodiment including a threaded joint, is particularly preferably coated with a layer having a larger friction value or a layer having a friction value larger than the friction value μ1 of the layer of the flared rear end. The friction value of the layer on the male thread or thread of the threaded joint is preferably 3 times, particularly at least 4 times, very preferably at least 5 times larger than the friction value μ1 of the layer of the flared rear end or the first layer. Furthermore, the framework of the present disclosure includes that the layer on the male thread or thread of the threaded joint is applied by plasma coating. It has been found that plasma coating is particularly effective for applying a coating with a varying friction value.

[0008] The present disclosure is based on the finding that by using the plasma coating according to the present disclosure, the friction value of the flared rear end can be reproducibly set as desired and in a very reliable and functional manner. Since damage to the pipe and damage to the coating on the pipe can be completely avoided, no signs of corrosion known from the prior art appear. In particular, a layer having a relatively small friction value can be applied very simply and inexpensively by plasma coating. By the method according to the present disclosure, a plurality of processing steps and the associated costs can be reduced.

[0009] In one embodiment of the present disclosure, at least a predetermined region of the flare front end portion that is spaced apart from the pipe and forms the end face of the pipe has one layer, i.e., a second layer, by plasma coating. The layer, i.e., the second layer, has a friction value μ2. Advantageously, the friction value μ2 is greater than or much greater than the friction value μ1 of the layer, i.e., the first layer, applied to the flare rear end portion. In one embodiment of the method according to the present disclosure, the first layer having a friction value μ1 is applied to the flare, particularly the flare rear end portion, at least in the region, by plasma coating, and the second layer having a friction value μ2 is applied to the flare, particularly the flare front end portion, at least in a predetermined region, by plasma coating. The second friction value μ2 is greater than the first friction value μ1. Advantageously, the second friction value μ2 is at least 3 times, particularly at least 4 times, preferably at least 5 times greater than the first friction value μ1, and preferably is applied to the layer at the flare rear end portion.

[0010] In a preferred embodiment of the present disclosure, the flare at the pipe end includes an F-type flare or an E-type flare. In the framework of the present disclosure, the F-type flare is particularly preferred. It is most preferred to use a pipe made of metal or substantially made of metal. The framework of the present disclosure includes that the flare, particularly the F-type flare, is integrally formed with the pipe or the pipe end portion, and similarly, is made of metal or substantially made of metal.

[0011] The framework of the present disclosure includes that the surface to be coated by plasma coating is first cleaned, preferably by a plasma jet. This embodiment has been proven to be particularly effective in the framework of the present disclosure. Advantageously, particularly, the flare rear end portion of the flare of the pipe is cleaned by a plasma jet, and then, by plasma coating, a layer having a friction value μ1 is applied to the flare rear end portion or the surface of the flare rear end portion.

[0012] Particularly preferred embodiments of the method according to the present disclosure are characterized in that at least one layer applied by plasma coating consists of or consists essentially of at least one material or at least one substance selected from the group consisting of metals, metal salts, and polymers. The layer applied to the surface of the flare rear end preferably consists of or consists essentially of at least one material selected from the above group. In particular, the polymers used herein are fluoropolymers, polyolefins, and / or polyamides. The low-friction layer applied by plasma coating has at least one lubricant that reduces the friction value of the layer, and this lubricant is preferably a fluoropolymer, particularly polytetrafluoroethylene (PTFE) and / or molybdenum sulfide (MoS 2 ) is desirable. Advantageously, the layer having the lubricant is applied to the surface of the flare rear end by plasma coating. The layer applied by plasma coating basically consists of or consists essentially of various organic and / or organometallic compounds and / or mixtures thereof.

[0013] The framework of the present disclosure includes that the plasma coating is performed at normal pressure or atmospheric pressure. The plasma coating may basically be performed under other pressures, for example, under vacuum. However, plasma coating at normal pressure is preferred. Advantageously, the plasma coating is performed as physical vapor deposition and / or chemical vapor deposition.

[0014] The framework of the present disclosure includes that a plasma coating device for plasma coating is used, and the coating material is supplied to the plasma coating device as a powder. Advantageously, the coating material in the plasma coating device is converted into the gas phase and then deposited as a solid in at least the flare region of the pipe, particularly at the flare rear end of the pipe.

[0015] To solve the technical problem, the present disclosure teaches a pipe, preferably a pipe for an automobile. A flare is provided at at least one pipe end of the pipe. At least a predetermined region of the flare has at least one layer applied by a plasma coating. Advantageously, at least a predetermined region of the rear end portion of the flare has at least one layer applied by a plasma coating. This layer advantageously has a relatively small or very small friction value.

[0016] To solve the technical problem, the present disclosure further teaches a pipe connection device for connecting pipes, in particular pipes for automobiles. This connection device includes at least one pipe and at least one screw element, in particular a screwed joint, and at least one surface of the screw element is in contact with a plasma-coated flare surface. The screw element or the screwed joint preferably contacts the rear end portion of the plasma-coated flare. The framework of the present disclosure includes that at least a predetermined region of the screw element or the screwed joint has a coating, in particular a coating of a thread or a male thread. The friction value μ3 of the thread coating is greater than the friction value μ1 of the layer applied by plasma coating at the rear end portion of the flare of the pipe, preferably very large. Advantageously, the friction value μ3 of the thread coating is at least twice, in particular at least three times, preferably at least four times, very preferably at least five times greater than the friction value μ1 of the layer applied by plasma coating at the rear end portion of the flare.

[0017] The present disclosure is based on the finding that the flare of a pipe, particularly the rear end portion of the flare, can be coated in a particularly simple and inexpensive manner, and the frictional value of the layer can be set with high reproducibility. No adverse damage to the flare surface or the pipe surface occurs. As a result, in contrast to known processes according to the prior art, signs of corrosion can be avoided. The steps required for the method according to the present disclosure are clearly fewer than the known process steps according to the prior art. In this regard, the production of pipes according to the present disclosure can be carried out in a very short time, with a reduction in manufacturing complexity and at a lower cost. The coated flare has an optimal surface quality, and this surface quality can be achieved with high reproducibility. Overall, the present disclosure is characterized by simplicity, low labor, and low cost. Since the adverse torsion of the pipe can be extremely effectively avoided by the flare coated according to the present disclosure, substantially no reverse torque that would damage the pipe occurs.

[0018] Hereinafter, the present disclosure will be described in more detail based on the drawings showing exemplary embodiments.

Brief Description of the Drawings

[0019]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0020] Figure 1 shows a pipe 1 according to the present disclosure that has been processed based on the method according to the present disclosure. In a preferred embodiment and an exemplary embodiment, the pipe 1 is a pipe for an automobile. The pipe 1 has a flare 2 at one pipe end. Preferably, in an exemplary embodiment, the flare 2 is designed as an F-type flare. In a particularly preferred configuration and an exemplary embodiment, the flare 2 has a first layer 4 at the flare rear end 3. The layer 4 preferably has a relatively small coefficient of friction μ1. The layer at the flare rear end 3 is applied in accordance with the present disclosure by means of a plasma coating, specifically, preferably by means of the plasma coating device 5 shown in Figure 3.

[0021] In the exemplary embodiment according to Figure 1, the flare front end 6 forms the end face of the pipe 1 and has a second layer 7. The second layer 7 has a coefficient of friction μ2. Advantageously, the second layer 7 is applied by means of a plasma coating. In the framework of the present disclosure, the coefficient of friction μ2 of the second layer 7 is greater than the coefficient of friction μ1 of the first layer at the flare rear end 3, preferably significantly greater than the coefficient of friction μ1. In an exemplary embodiment, the coefficient of friction μ2 is three times the coefficient of friction μ1. Advantageously, the pipe 1 is made of metal. Similarly, the flare 2 or the F-type flare is made of metal and is preferably formed integrally with the pipe 1.

[0022] Figure 2 shows an exemplary embodiment of a pipe connection device according to the present disclosure. The pipe 1 shown in Figure 1 is connected to this connection device. In the exemplary embodiment in Figure 2, the pipe 1 is preferably connected to a connection element or connection block 8. In an exemplary embodiment, the connection block 8 has an integrated second pipe 9. In an exemplary embodiment, the pipe passes through the axial hole 10 of the threaded joint 11. The threaded joint 11 has a male thread 12. In the exemplary embodiment in Figure 2, the threaded joint 11 is screwed into a complementary female thread corresponding to the male thread 12. In the screwed state, the end face 13 of the threaded joint 11 contacts the flare rear end 3 of the flare 2. The threaded joint 11 presses the flare 2, i.e., the flare front end 6, against the sealing surface 14 of the connection block 8.

[0023] The first layer 4 at the flare rear end portion 3 having a small friction value μ1 reduces the friction between the end face 13 of the screw joint 11 and the flare rear end portion 3, thereby effectively preventing the torsion of the pipe 1. The present disclosure is based on the finding that coating the flare rear end portion 3 with the first layer 4 by plasma coating brings particularly advantageous results. In one embodiment and the exemplary embodiment shown in FIG. 2, the male thread 12 of the screw joint 11 has a third layer 15. The third layer 15 has a friction value μ3. In the exemplary embodiment, the friction value μ3 of the third layer 15 is preferably greater than the friction value μ1 of the first layer 4 of the flare rear end portion 3, and particularly preferably significantly greater than the friction value μ1 of the layer 4. In the exemplary embodiment, the friction value μ3 of the layer 15 in the male thread 12 of the screw joint 11 is at least three times greater than the friction value μ1 of the first layer at the flare rear end portion 3. Further, the framework of the present disclosure includes that the end face 13 of the screw joint 11 has a layer with a small friction value. The layer may be the same layer applied to the flare rear end portion 3. Further, the framework of the present disclosure includes that the coating on the end face 13 of the screw joint 11 is similarly applied by plasma coating. Also, the third layer 15 in the male thread 12 of the screw joint 11 having a relatively large friction value μ3 is basically applied by plasma coating. The present disclosure is based on the finding that when applying a layer by plasma coating, the friction value of the layer can be accurately set particularly as desired.

[0024] FIG. 3 shows a plasma coating apparatus 5 preferably used for implementing the method according to the present disclosure. FIG. 3 shows the coating of the flare rear end portion 3 including the first layer 4 by plasma coating. The plasma coating apparatus 5 has an electrode 16 and a gas supply line 17. Further, a flow path 18 is provided. Through this flow path, a material for plasma coating is preferably introduced as powder. Also shown is a plasma jet 19 for coating the flare rear end portion 3.

Claims

1. A method for processing a pipe (1), comprising: forming a flare (2) at at least one pipe end of the pipe (1); providing at least one layer (4) in at least a predetermined region of the flare (2) to change the frictional properties of the coating surface of the flare (2); coating the flare (2) by plasma coating; providing a first layer (4) by plasma coating in at least a predetermined region of the flare rear end (3) facing the pipe (1); the first layer (4) has a first friction value μ1; providing a second layer (7) by plasma coating in at least a predetermined region of the flare front end (6) forming the end face of the pipe (1) spaced apart from the pipe (1); the second layer (7) has a second friction value μ2; the second layer (7) having the second friction value μ2 is applied to the flare (2) in at least a predetermined region by plasma coating; the second friction value μ2 is greater than the first friction value μ1; A method characterized by the above.

2. The method according to claim 1, wherein the flare (2) is formed as an F-type flare or an E-type flare.

3. The method according to claim 1, wherein the pipe (1) is made of metal.

4. The method according to claim 1, wherein at least one layer (4, 7) applied by plasma coating is made of at least one material selected from the group consisting of metals, metal salts, polymers, and fluoropolymers.

5. The method according to claim 1, wherein plasma coating is performed at normal pressure or atmospheric pressure.

6. The method according to claim 1, wherein plasma coating is performed as physical vapor deposition and / or chemical vapor deposition.

7. using a plasma coating device (5) for plasma coating; supplying a coating material as a powder to the plasma coating device (5); A method characterized by the above.

8. The method according to claim 1, wherein the coating material in the plasma coating device (5) is converted into a gas phase and then deposited as a solid in at least a predetermined region of the flare (2) of the pipe (1).

9. A pipe processed by the method according to claim 1, comprising: having a flare (2) at at least one pipe end; A pipe, characterized in that at least one layer (4, 7) applied by plasma coating is provided in at least a predetermined region of the flare (2).

10. A pipe connection device for connecting pipes (1), comprising: at least one pipe (1) treated by the method according to Claim 1, and at least one thread element forming a screwed joint (11); A pipe connection device, characterized in that at least one surface of the thread element is in contact with the surface of the plasma-coated flare.

11. The pipe connection device according to Claim 10, characterized in that the thread element is in contact with the plasma-coated rear end portion (3) of the flare.

12. At least a predetermined region of the thread element has a thread coating, The pipe connection device according to Claim 10, characterized in that a third friction value μ3 of the thread coating is greater than a first friction value μ1 of the layer (4) applied to the rear end portion (3) of the flare by plasma coating.

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