METHOD FOR COATING A SCREW ELEMENT, SCREW ELEMENT AND PIPE CONNECTION DEVICE

Abstract

A method for coating a screw element, in particular a screw element for connecting pipes, preferably motor vehicle pipes, wherein the screw element has at least one thread as well as at least one unthreaded contact surface. At least areas of the thread are provided with a first coating, and at least areas of the unthreaded contact surface are provided with a second coating. Both the first coating of the thread as well as the second coating of the unthreaded contact surface are applied to the thread or to the unthreaded contact surface via plasma coating.

Claims

1. A method for coating a screw element for connecting pipes, wherein the screw element has at least one thread as well as at least one unthreaded contact surface, wherein at least areas of the thread are provided with a first coating, and wherein at least areas of the unthreaded contact surface are provided with a second coating, wherein both the first coating of the thread as well as the second coating of the unthreaded contact surface, are applied to the thread or to the unthreaded contact surface via plasma coating.

2. The method according to claim 1, wherein the first coating has a friction value 1 and the second coating has a friction value 2, and wherein the first friction value 1 is larger than the second friction value 2.

3. The method according to claim 1, wherein the first friction value 1 measures at least two times the second friction value 2.

4. The method according to claim 1, wherein the layer thickness of the first coating measures 1 m to 25 m, and/or wherein the layer thickness of the second coating measures 5 m to 100 m.

5. The method according to claim 1, wherein the used screw element is a screw bolt or a screw fitting, which has a thread designed like a male thread, at least areas of which are provided with the first coating.

6. The method according to claim 5, wherein the end face of the screw fitting has an unthreaded contact surface, at least areas of which are provided with the second coating, and/or wherein a thread-sided underside of a screw head of the screw fitting has an unthreaded contact surface, at least areas of which are provided with the second coating.

7. The method according to claim 1, wherein the plasma coating for the first coating and for the second coating is performed at normal pressure or at atmospheric pressure.

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

9. The method according to claim 1, wherein a plasma coating device is used for plasma coating, and wherein the material for the first coating and/or the material for the second coating is fed to the plasma coating device as a powder.

10. The method according to claim 1, wherein the material for the first coating and/or the material for the second coating in the plasma coating device is converted into the gas phase, and then deposited in a solid form onto the thread and/or onto the unthreaded contact surface.

11. The method according to claim 1, wherein at least one material from the metal, metal salt, polymer group is used for the first coating and/or the second coating.

12. A screw element manufactured based upon a method according to claim 1 for connecting pipes, wherein the screw element has at least one thread as well as at least one unthreaded contact surface, wherein at least areas of the thread are provided with a first coating, and wherein at least areas of the unthreaded contact surface are provided with a second coating, characterized in that both the first coating of the thread as well as the second coating of the unthreaded contact surface are applied via plasma coating.

13. A pipe connection device for connecting pipes, with a screw element according to claim 12, wherein a pipe is connected to the screw element, and wherein the screw element is connected to a connection element via a screwed connection.

14. The pipe connection device according to claim 13, wherein the screw element is a screw fitting with an axial bore, with the axial bore being penetrated by a pipe, wherein the pipe end of the pipe has a flare, and that the unthreaded contact surface provided with the second coating at the end face of the screw fitting abuts against the rear flare side of the flare.

15. Use of a screw element according to claim 12 in motor vehicle construction for fuel lines or hydraulic lines.

16. The method according to claim 1, wherein the first friction value measures at least three times the second friction value 2.

17. The method according to claim 1, wherein the layer thickness of the first coating measures 2 m to 20 m, and/or wherein the layer thickness of the second coating measures 5 m to 50 m.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The disclosure will be described in more detail below based upon a drawing that only illustrates an exemplary embodiment. Shown schematically on:

[0023] FIG. 1: is a longitudinal section through a screw element according to the disclosure designed as a screw fitting,

[0024] FIG. 2: is a pipe connection device with the screw fitting according to FIG. 1 and connected pipe, and

[0025] FIG. 3: is a schematic view of a plasma coating device for implementing the method according to the disclosure.

DETAILED DESCRIPTION

[0026] The figures show a screw element according to the disclosure designed as a screw fitting 1, which preferably and in the exemplary embodiment is provided for connecting a pipe 2. In particular, the pipe 2 involves a motor vehicle pipe. The screw fitting 1 has a thread 3 as well as unthreaded contact surfaces 4 and 5. The unthreaded contact surface 4 is arranged at the end face of the screw fitting 1, and the unthreaded contact surface 5 is arranged on the thread-sided underside of the screw head 6 of the screw fitting 1.

[0027] In the exemplary embodiment, the thread 3 or the male thread of the screw fitting 1 is preferably completely provided with a first coating 7. In the exemplary embodiment, the two unthreaded contact surfaces 4, 5 are preferably completely provided with a second coating 8. The friction value 1 of the first coating 7 is larger than the second friction value 2 of the second coating 8. In the exemplary embodiment, the first friction value 1 preferably measures five times the second friction value 2. In the exemplary embodiment, the screw fitting 1 preferably consists of metal or essentially of metal.

[0028] In the preferred embodiment of the screw fitting 1 shown on FIG. 1, the first coating 7 with the higher friction value 1 was applied in the area of the thread 3 by means of plasma coating. The first coating 7 forms the outer surface of the screw fitting 1 in the area of the thread 3. The second coating 8 with the lower friction value 2 was applied in the area of the unthreaded contact surfaces 4 and 5 by means of plasma coating. The second coating 8 forms the outer surface of the screw fitting 1 in the area of these unthreaded contact surfaces 4 and 5.

[0029] FIG. 2 shows a screw fitting 1 generated according to the disclosure in an operating state or a pipe connection device according to the disclosure with the screw fitting 1. In the exemplary embodiment, the pipe 2 preferably penetrates the screw fitting 1 in an axial direction, and the end of this pipe 2 has a face element, which in the exemplary embodiment is designed like a flare 9, as recommended. It lies within the framework of the disclosure that a metal flare 9 be involved, which in the exemplary embodiment is preferably integrally molded onto the pipe end. In the exemplary embodiment according to FIG. 2, the screw fitting 1 is screwed into a connection element designed as a connecting block 10. In the exemplary embodiment, the connecting block 10 best has an integrated second pipe 11. The end face sealing surface 12 of the screw fitting 1 presses the flare 9 against a connecting surface of the connecting block 10. For this purpose, the thread 3 or male thread of the screw fitting 1 is screwed into the blind hole 13 of the connecting block 10. In the exemplary embodiment, the blind hole 13 has a corresponding complementary female thread. The thread 3 or the male thread of the screw fitting 1 is provided with the first coating 7, which was applied according to the disclosure via plasma coating. The unthreaded contact surface 4 at the face end of the screw fitting has the second coating 8, which was likewise applied by means of plasma coating. The unthreaded contact surface 5 on the thread-sided underside of the screw head 6 is likewise provided with the second coating 8, which here as well was applied by means of plasma coating.

[0030] FIG. 3 shows a plasma coating device 14 suitable for the method according to the disclosure. In the exemplary embodiment according to FIG. 3, this plasma coating device 14 is used to apply the second coating 8 with the lower friction value 2 to the unthreaded contact surface 4 at the end face of the screw fitting 1. In the usual manner, the plasma coating device has an electrode 15 as well as a gas supply line 16. In the exemplary embodiment, the material for the coating is preferably supplied through the channel 17 as a powder. The plasma jet 18 is discernible above the surface to be coated. In a preferred embodiment, the surface to be coated can be cleaned prior to plasma coating with the plasma coating device or with its plasma jet 18, as was already pointed out above.