Method of improving a corrosion protection of a hollow shaft

Abstract

A method for improving a corrosion protection of a hollow shaft may include introducing a lance into the hollow shaft, and cleaning and expelling a liquid from an inside of the hollow shaft via spraying a gas from the lance. The method may also include applying a corrosion protection medium onto an inner lateral surface of the hollow shaft at least in certain regions, and closing off the hollow shaft.

Claims

1. A method for improving a corrosion protection of a hollow shaft, comprising: introducing a lance into the hollow shaft; cleaning and expelling a liquid from an inside of the hollow shaft via spraying a gas from the lance; applying a corrosion protection medium onto an inner lateral surface of the hollow shaft at least in certain regions; and closing off the hollow shaft; wherein closing off the hollow shaft includes connecting a plug to one longitudinal end of the hollow shaft prior to spraying the gas from the lance and prior to applying the corrosion protection medium; and wherein applying the corrosion protection medium to the inner lateral surface of the hollow shaft includes applying the corrosion protection medium to an axially facing surface of the plug.

2. A method for improving a corrosion protection of a hollow shaft, comprising: introducing a lance into the hollow shaft; cleaning and expelling a liquid from an inside of the hollow shaft via spraying a gas from the lance; applying a corrosion protection medium onto an inner lateral surface of the hollow shaft at least in certain regions; and closing off at least one end of the hollow shaft to prevent the corrosion protection medium from leaking out of the hollow shaft wherein the at least one longitudinal end of the hollow shaft is closed off prior to spraying the gas from the lance and prior to applying the corrosion protection medium; introducing the lance into the hollow shaft includes moving the lance to a first position adjacent to the closed off longitudinal end of the hollow shaft; and spraying the gas from the lance includes pulling the lance out of the hollow shaft from the first position while spraying the gas from the lance.

3. The method according to claim 2, wherein: closing off the at least one longitudinal end of the hollow shaft includes connecting a plug to one longitudinal end of the hollow shaft prior to spraying the gas from the lance and prior to applying the corrosion protection medium; and applying the corrosion protection medium to the inner lateral surface of the hollow shaft includes applying the corrosion protection medium to an axially facing surface of the plug.

4. A method for improving a corrosion protection of a hollow shaft, comprising: introducing a lance into the hollow shaft; cleaning and expelling a liquid from an inside of the hollow shaft via spraying a gas from the lance; applying a corrosion protection medium onto an inner lateral surface of the hollow shaft at least in certain regions; and closing off the hollow shaft; wherein spraying the gas from the lance includes passing the gas through at least one first nozzle of the lance; wherein applying the corrosion protection medium to the inner lateral surface of the hollow shaft includes passing the corrosion protection medium through at least one second nozzle of the lance; and wherein the at least one second nozzle is disposed axially behind at least one first nozzle relative to a direction the lance is introduced into the hollow shaft.

5. The method according to claim 4, wherein applying the corrosion protection medium includes applying at least one of an oil, a grease, a wax, a dewatering medium with a corrosion protection medium, and a drying agent to the inner lateral surface of the hollow shaft.

6. The method according to claim 4, wherein spraying the gas from the lance includes spraying an inert gas.

7. The method according to claim 4, wherein spraying the gas from the lance includes spraying argon gas.

8. The method according to claim 4, wherein spraying the gas from the lance includes spraying nitrogen gas.

9. The method according to claim 4, further comprising, while spraying the gas from the lance, moving the lance coaxially to the hollow shaft at a distance of 0.5 mm to 3 mm from the inner lateral surface.

10. The method according to claim 4, further comprising: performing a forward movement of the lance while spraying out the gas and expelling any of the liquid present in the hollow shaft; and performing a reverse movement of the lance while applying the corrosion protection medium to the inner lateral surface of the hollow shaft.

11. The method according to claim 4, further comprising performing a forward movement of the lance while (i) spraying out the gas and expelling any of the liquid present in the hollow shaft and (ii) behind the spraying relative to the entry direction, applying the corrosion protection medium to the inner lateral surface of the hollow shaft.

12. The method according to claim 4, further comprising introducing a plug into a longitudinal end of the hollow shaft (i) before spraying the gas from the lance and (ii) before applying the corrosion protection medium.

13. The method according to claim 4, further comprising, while spraying the gas from the lance, moving the lance coaxially to the hollow shaft at a distance of 1 mm to 2 mm from the inner lateral surface.

14. The method according to claim 4, further comprising: performing a forward movement of the lance while (i) spraying out the gas and expelling any of the liquid present in the hollow shaft and (ii) applying the corrosion protection medium to the inner lateral surface of the hollow shaft; performing a reverse movement of the lance after performing the forward movement of the lance; and applying another layer of the corrosion protection medium to the inner lateral surface of the hollow shaft while performing the reverse movement of the lance.

15. The method according to claim 4, further comprising performing a rotational movement of the lance while spraying the gas from the lance.

16. The method according to claim 4, further comprising providing the hollow shaft with at least one ventilation hole that fluidically connects the inside of the hollow shaft and an outside of the hollow shaft in a radial direction prior to spraying the gas from the lance and prior to applying the corrosion protection medium.

17. The method according to claim 4, wherein: closing off the hollow shaft includes closing off one longitudinal end of the hollow shaft prior to spraying the gas from the lance and prior to applying the corrosion protection medium; the lance is introduced into the hollow shaft in an entry direction; and spraying the gas from the lance includes spraying a gas jet in a direction opposite the entry direction while moving the lance in the entry direction.

18. The method according to claim 4, wherein: closing off the hollow shaft includes closing off one longitudinal end of the hollow shaft prior to spraying the gas from the lance and prior to applying the corrosion protection medium; introducing the lance into the hollow shaft includes moving the lance to a first position adjacent to the closed off longitudinal end of the hollow shaft; and spraying the gas from the lance includes pulling the lance out of the hollow shaft from the first position while spraying the gas from the lance.

19. The method according to claim 4, wherein: closing off the hollow shaft includes connecting a plug to one longitudinal end of the hollow shaft prior to spraying the gas from the lance and prior to applying the corrosion protection medium; and applying the corrosion protection medium to the inner lateral surface of the hollow shaft includes applying the corrosion protection medium to an axially facing surface of the plug.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) There it shows, in each case schematically,

(2) FIGS. 1 to 4 each show different method steps for carrying out the method according to the invention for the corrosion protection of an initially open hollow shaft.

(3) FIGS. 5 to 8 each show different method steps for carrying out the method according to the invention for the corrosion protection with a hollow shaft closed off on one side.

DETAILED DESCRIPTION

(4) According to FIGS. 1 to 4, different method steps for carrying out the method according to the invention for producing a corrosion protection of a hollow shaft 1 are shown, wherein in the first method step, which is shown in FIG. 1, initially a lance 2 is introduced into the hollow shaft 1, which can be formed for example as a camshaft 3. On introducing the lance 2 into the hollow shaft 1, a gas 4, in particular air, is sprayed out by means of the lance 2, by means of which the hollow shaft 1 is cleaned from the inside, in particular liquid 5, for example water, or moisture present there is expelled. To this end, the hollow shaft 1 can be arranged horizontally, obliquely or even vertically, wherein according to FIGS. 1 to 4 exclusively a horizontal position of the hollow shaft 1 is shown.

(5) In a following method step shown according to FIG. 2, a corrosion protection medium 6 is applied to an inner lateral surface 7 of the hollow shaft 1 by means of the lance 2 at least in certain regions, upon which in the method step according to FIG. 3, the lance 2 is moved out of the hollow shaft 1. Finally, the hollow shaft 1, in the fourth method step, shown according to FIG. 4, is closed, for example by means of a plug 9 or a cover 8.

(6) By way of the method according to the invention, a significant lowering of a corrosion risk is achievable, since under certain conditions liquid 5 or moisture still present in the hollow shaft 1 can be preferentially removed entirely prior to applying the corrosion protection medium 6.

(7) In FIGS. 1 to 3, always only a single lance 2 is shown, by means of which during a forward movement (see FIG. 1), i.e. an entry movement of the lance 2 into the hollow shaft 1, gas 4, in particular air, is sprayed out and thereby the liquid 5 present in the hollow shaft 1 is expelled, while with the same lances 2 during a reverse movement, i.e. an exit movement of the lance 2 from the hollow shaft 1 (see FIG. 2) the corrosion protection medium 6 is applied to the inner lateral surface 7 of the hollow shaft 1. Purely theoretically it is also conceivable however that for this purpose two different lances 2 are provided, of which one is designed for spraying out the gas 4, in particular the air, and the other for applying or spraying out the corrosion protection medium 6. Purely theoretically it is also conceivable that the lance 2 during a forward movement sprays out gas 4 and because of this removes the liquid 5 present in the hollow shaft 1 and simultaneously, in entry direction behind that, applies the corrosion protection medium 6 by way of suitable nozzles to the inner lateral surface 7 of the hollow shaft 1. This would have the major advantage that applying the corrosion protection medium 6 by means of the lance 2 is possible both during the entry movement and also during the exit movement and because of this can apply a larger quantity of corrosion protection medium 6.

(8) Viewing FIG. 1 further it is noticeable that the lance 2 during the spraying-out of the gas 4, in particular of the air, and according to FIG. 2 also during the applying of the corrosion protection medium 6, is moved with a distance d of 0.5 mm to 3 mm, in particular with a distance d of 1 mm to 2 mm, to the inner lateral surface 7 of the hollow shaft 1, as a result of which in particular during the spraying-out of the gas 4 the pressure required for the preferentially complete expulsion of the liquid 5 can be built up. There, beside a purely coaxial, i.e. linear movement of the lance 2, a rotating of the same is also conceivable.

(9) Viewing FIG. 4 it is evident on the hollow shaft 1 shown there that the same comprises a passage opening 10 (ventilation hole), via which a ventilation of an interior 11 of the hollow shaft 1, in particular of the camshaft 3, is possible during the operation. By way of such a passage opening 10, moisture or liquid can be expelled from the interior 11 of the hollow shaft 1 and under certain conditions oil, i.e. a corrosion protection medium 6, be introduced into the interior 11 during the operation of the hollow shaft 1. Such a passage opening 10 is usually arranged in a place that is not covered by a bearing or a cam with installed camshaft.

(10) According to FIGS. 5 to 8, different method steps for carrying out the method according to the invention for producing a corrosion protection of a hollow shaft 1 are likewise shown, but which is already closed on one side by a plug 9 or a cover 8 at the beginning. In the first method step shown in FIG. 5, a lance 2 is initially introduced into the hollow shaft 1, which can be formed for example as camshaft 3, and in the process a gas 4, in particular air, sprayed out by means of the lance 2, by means of which the hollow shaft 1 is cleaned from the inside at least in certain regions, in particular liquid 5, for example water or moisture present there, is expelled. To this end, the hollow shaft 1 can be arranged horizontally, obliquely or even vertically, wherein according to FIGS. 5 to 8 exclusively a horizontal position of the hollow shaft 1 is shown. The entry movement can even take place with a gas jet directed against the entry movement, wherein it is also conceivable that the lance 2 is initially moved in up to just before the cover 8 or the plug 9 without pressure and the hollow shaft 1 blown out only during a pulling-out which is not shown.

(11) In a method step following thereon and shown according to FIG. 6, a corrosion protection medium 6 is applied at least in certain regions by means of the lance 2 on an inner lateral surface 7 of the hollow shaft 1 and in particular also on an end face of the cover 9 or of the plug 9, upon which in the method step according to FIG. 7 the lance 2 is moved out of the hollow shaft 1.

(12) Here, the corrosion protection medium 6 can be output only over a length L and because of this not directly as far as to the right longitudinal end of the hollow shaft 1. This has the advantage that during a thermal joining of the cams or other components, no running out of the corrosion protection medium 6 from the hollow shaft 1 has to be feared. The introducing of the corrosion protection medium 6 only limited over a length L could also be employed for the case in which the plug 9 is positioned only thereafter. Here, the advantage would be offered that the hollow shaft 1 with corrosion protection medium 6 already introduced could be heated and the same need not have to be injected into a hot hollow shaft 1, so that an explosion risk can be reduced. The region outside the length L not wetted with corrosion protection medium 6 still offers sufficient adhesion surface for the torque transmission between inner lateral surface 7 and plug 9.

(13) Obviously it is also clear that the hollow shaft 1 can be initially blown out as hollow shaft 1 that is open on both sides and subsequently closed on one side with a cover 8 or a plug 9. Following this, the lance 2 is moved into the hollow shaft once more and gas 4, in particular air, ejected in order to clean for example a plug joint and the inner lateral surface 7. During a following reverse movement of the lance 2, the corrosion protection medium 6 is then output. Alternatively, this can obviously also be output during a second entering of the lance 2.

(14) Finally, the hollow shaft 1, in the fourth method step, which is shown according to FIG. 8, is also closed off at the other longitudinal end by means of a plug 9 or a cover 8. To this end, the hollow shaft 1 can be heated again without it having to be feared that in the process the corrosion protection medium 6 leaks out of the same.

(15) It is likewise clear that the lance 2 can be moved into the hollow shaft 1 initially without air output from the lance 2, after which a “blowing”, i.e. an air output from the lance 2, subsequently takes place in order to blow traces of water out of a joint, in particular out of a plug joint. During the subsequent pulling out of the lance 2 from the hollow shaft 1, the corrosion protection medium 6 is then applied to the inner lateral surface 7 of the hollow shaft 1 at least in certain regions. Finally, a closing-off of the hollow shaft 1 can take place which was initially closed only on one side.

(16) As corrosion protection medium 6, for example an oil, a grease, a wax, a dewatering medium with a corrosion protection medium and/or a drying agent can be used for example, wherein in particular oils, greases and wax seal the inner lateral surface 7 and by way of this keep any moisture or condensed remnants unintentionally entering the hollow shaft 1 away from the hollow shaft 1 even after the same has been closed, thereby protecting it from corrosion.

(17) The gas 4 used for expelling the liquid 5 can be for example air or an inert gas, in particular argon, nitrogen, helium or similar. Such inert gases have the major advantage that these are inert and because of this do not or hardly react chemically.

(18) With the method according to the invention any liquid 5 that may be present in the hollow shaft 1 can be almost completely expelled and at the same time the inner lateral surface 7 of the hollow shaft 1 sealed, as a result of which altogether a significantly improved corrosion protection can be achieved.