Process for hot-rolling metallic hollow bodies and corresponding hot-rolling mill

Abstract

In order to optimize the lubrication of a rolling rod in a process for hot-rolling metallic, elongate hollow bodies (21) by means of the rolling rod (2), which is arranged in the hollow body and to which lubricant is applied before the hot-rolling operation, the lubricant is applied to the rolling rod in solid form.

Claims

1. A method for hot-rolling a metallic, elongated hollow body, said method comprising: disposing a rolling rod in the hollow body; providing a solid lubricant as a lubricant film; applying the lubricant film in solid form to the rolling rod; and subsequently hot rolling the hollow body after the lubricant film is applied in solid form to the rolling rod; wherein a first roller disposed adjacent to the rolling rod presses the lubricant film onto the rolling rod; and wherein: a functional agent is provided as a functional agent film or as a functional agent sheet and the functional agent film or the functional agent sheet is applied in solid form to the rolling rod or to the lubricant film before the lubricant film is applied in solid form to the rolling rod.

2. The method according to claim 1, wherein before the lubricant film is applied in solid form to the rolling rod, the lubricant film is prefabricated.

3. The method according to claim 2, wherein the lubricant film is prefabricated in a fabrication station and the lubricant film is applied to the rolling rod in a lubricant application station, the lubricant application station being disposed separate from the fabrication station.

4. The method according to claim 1, wherein the lubricant film is rolled onto the rolling rod via the first roller.

5. The method according to claim 1, wherein the lubricant film has a varying layer thickness along the rolling rod.

6. The method according to claim 1, wherein the lubricant film is applied to the rolling rod in multiple layers.

7. The method according to claim 6, wherein the lubricant layers have different material properties.

8. The method according to claim 1, wherein the functional agent film or the functional agent sheet is applied to the lubricant film before application of the lubricant film to the rolling rod.

9. The method according to claim 8, wherein the functional agent comprises an adhesive, a binder, a release agent or an insulation agent.

10. The method according to claim 1, wherein the functional agent film or the functional agent sheet is applied to the rolling rod before application of the lubricant film to the rolling rod.

11. The method according to claim 1, wherein the elongated hollow body comprises a shell or a pipe.

12. The method according to claim 1, wherein the lubricant film comprises graphite.

13. The method according to claim 1, wherein the lubricant film comprises a support material.

14. The method according to claim 13, wherein the support material is lost during the rolling process.

15. The method according to claim 1, wherein the elongated hollow body comprises steel.

16. The method according to claim 1, wherein a second roller disposed adjacent to the rolling rod presses the lubricant film onto the rolling rod.

17. The method according to claim 1, wherein the first roller is a half-round roller.

18. A method for hot-rolling a metallic, elongated hollow body, said method comprising: disposing a rolling rod in the hollow body; providing a solid lubricant as a graphite lubricant sheet; applying the graphite lubricant sheet in solid form to the rolling rod; and subsequently hot rolling the hollow body after the graphite lubricant sheet is applied in solid form to the rolling rod; wherein a first roller disposed adjacent to the rolling rod presses the graphite lubricant sheet onto the rolling rod; and wherein: a functional agent is provided as a functional agent film or as a functional agent sheet and the functional agent film or the functional agent sheet is applied in solid form to the rolling rod or to the graphite lubricant sheet before the graphite lubricant sheet is applied in solid form to the rolling rod.

19. The method according to claim 18, wherein before the graphite lubricant sheet is applied in solid form to the rolling rod, the graphite lubricant sheet is prefabricated.

20. The method according to claim 19, wherein the graphite lubricant sheet is prefabricated in a fabrication station and the graphite lubricant sheet is applied to the rolling rod in a lubricant application station, the lubricant application station being disposed separate from the fabrication station.

21. The method according to claim 18, wherein the graphite lubricant sheet is rolled onto the rolling rod via the first roller.

22. The method according to claim 18, wherein the graphite lubricant sheet has a varying layer thickness along the rolling rod.

23. The method according to claim 18, wherein the graphite lubricant sheet is applied to the rolling rod in multiple layers.

24. The method according to claim 23, wherein the lubricant layers have different material properties.

25. The method according to claim 18, wherein the functional agent film or the functional agent sheet is applied to the graphite lubricant sheet before application of the graphite lubricant sheet to the rolling rod.

26. The method according to claim 25, wherein the functional agent comprises an adhesive, a binder, a release agent or an insulation agent.

27. The method according to claim 18, wherein the functional agent film or the functional agent sheet is applied to the rolling rod before application of the graphite lubricant sheet to the rolling rod.

28. The method according to claim 18, wherein the elongated hollow body comprises a shell or a pipe.

29. The method according to claim 18, wherein the graphite lubricant sheet comprises a support material.

30. The method according to claim 29, wherein the support material is lost during the rolling process.

31. The method according to claim 18, wherein the elongated hollow body comprises steel.

32. The method according to claim 18, wherein a second roller disposed adjacent to the rolling rod presses the graphite lubricant sheet onto the rolling rod.

33. The method according to claim 18, wherein the first roller is a half-round roller.

Description

(1) Further advantages, goals, and properties of the present invention will be explained using the following description of exemplary embodiments, which are particularly also shown in the attached drawing. The drawing shows:

(2) FIG. 1 the principle of pipe-rolling with an internal rolling rod, in this case a cross-rolling method;

(3) FIG. 2 the principle of pipe-rolling with an internal rolling rod, in this case a longitudinal rolling method;

(4) FIG. 3 spraying on of a liquid lubricant dispersion, by means of a nozzle ring, in schematic longitudinal section;

(5) FIG. 4 the arrangement, according to FIG. 3 in a sectional view through the rolling rod;

(6) FIG. 5 coating of a rolling rod by means of winding on a lubricant film;

(7) FIG. 6 rolling rod lubrication in which a lubricant film is unwound from rolls and pulled over the rolling rod longitudinally;

(8) FIG. 7 pressing on of lubricant onto a rotating mandrel rod, by way of an application band;

(9) FIG. 8 casting of lubricant powder onto a rolling rod;

(10) FIG. 9 a rolling-rod cycle of a hot-rolling mill having a lubricant application station;

(11) FIG. 10 rolling rod lubrication in which a lubricant sheet is unwound from rolls and pulled over the rolling rod longitudinally;

(12) FIG. 11 a cross-sectional view through a rolling rod with a lubricant film and a functional agent film disposed between the lubricant film and the rolling rod;

(13) FIG. 12 a cross-sectional view through a rolling rod with a lubricant film and a functional agent sheet disposed between the lubricant film and the rolling rod;

(14) FIG. 13 a cross-sectional view through a rolling rod with a lubricant sheet and a functional agent film disposed between the lubricant film and the rolling rod; and

(15) FIG. 14 a cross-sectional view through a rolling rod with a lubricant sheet and a functional agent sheet disposed between the lubricant film and the rolling rod.

(16) In hot-rolling of a work piece 1 by means of a rolling rod 2, as shown schematically in FIGS. 1 and 2, a hollow block, as the work piece 1, in which a corresponding rolling rod 2 is disposed, is guided past rollers, whether cross-rollers 3 (see FIG. 1) or longitudinal rollers 4 (see FIG. 2), whereby the rollers 3, 4 form the work piece 1 accordingly, in the direction toward the rolling rod 2, which accordingly exerts a counter-pressure to the rollers 3, 4, so that after rolling, an elongated internal opening in the work piece 1 remains. In this connection, however, the rolling rod 2 enters into interaction with the work piece 1 not with pressure but rather in sliding or rubbing manner. Accordingly, a lubricant is generally provided between work piece 1 and rolling rod 2, in order to accordingly reduce the stress both for the work piece 1 and for the rolling rod 2. Also, it must be taken into consideration that such rolling processes take place at relatively high temperatures, particularly also at temperatures above 1000 C.

(17) In this connection, it is known from the state of the art to apply a lubricant dispersion 6 onto a rolling rod 2 from a nozzle ring 7, which rod is being guided past the nozzle ring 7 by means of transport rollers 5, for example (see FIGS. 3 and 4), in order to make a corresponding lubricant layer 15 available. However, corresponding suspensions have the disadvantage that the solvent can evaporate in uncontrolled manner on the hot rolling rod 2, so thatin order to ensure a sufficient amount of lubricanta relatively large amount of lubricant must be sprayed on. Furthermore, there is the risk that the lubricant will evaporate as friction wear after evaporation of the solvent, and therefore will no longer be available for the rolling process. This is remedied, according to the state of the art, in that dry powder, directed over an electrical field, is supposed to be applied. However, it is not possible to eliminate the risk of uncontrolled friction wear in this way. Likewise, targeted application continues to be very difficult, particularly since the electrical field is very difficult to control and to maintain in the desired manner under actual operating conditions. In the present case, this is ensured by means of control of the lubricant layer, not shown, by means of which the layer thickness of the lubricant is measured before introduction of the lubricated rolling rod 2 into the hollow block 1, and then the throughput through the nozzle ring 7 is acted on to regulate it, in order to be able to compensate for possible losses caused by friction wear or dropping off.

(18) As shown in FIG. 5 for example, the press-on apparatus may include at least one film winding apparatus 37. By means of the use of a lubricant film 8 (see FIG. 5), which is applied to the rolling rod 2 from a supply roll 9, to form a lubricant layer 15, this disadvantage can be countered, also in simple and operationally reliable manner. Because the lubricant is applied in solid form, the risk of uncontrolled evaporation of liquid does not exist. Likewise, the risk of uncontrolled friction wear can be minimized by means of this solid form. In this connection, it is understood, as is directly evident from FIG. 5, that the lubricant film 8 can be wound around the rolling rod 2 in spiral shape, with joined edges. Likewise, however, an overlap or a certain gap between the individual windings can remain, thereby making it possible to control the amount of lubricant in targeted manner, and also to vary it locally. Likewise, it is obvious that in this manner, multiple layers, particularly also multiple layers of different lubricant films 8, can accordingly be wound onto the rolling rod 2. It is also understood that the lubricant film 8 can be provided with a functional agent 36, such as a binder, an adhesive, or the like, before being wound ondepending on the requirements. In this connection, the lubricant film 8 can also be configured to be self-adhesive, or a suitable adhesive is applied to the rolling rod 2 in advance. Likewise, it is possible that the lubricant film 8 comprises a support layer, for example composed of paper, cellulose, or the like, wherebyif necessarythe support layer can also be pulled off after the lubricant has been applied to the rolling rod 2, if the lubricant layer then remains on the roller rod 2 with sufficient inherent stability, something that can be guaranteed by means of a suitable adhesive or also by means of pressing it on.

(19) As shown as an example in FIG. 6, the lubricant film 8 can also be unwound longitudinally from a supply roll 9 and applied to the rolling rod 2, for example by means of two half-round rollers 10, whereby in the exemplary embodiment according to FIG. 6, the work is done with two separate lubricant films 8, which are applied on both sides, by means of an application roller 10 each. Likewise, further supply rolls 9 with lubricant films 8 can be disposed around the rolling rod 2, and can interact with corresponding application rollers 10. Also, it is possible that only one lubricant film 8 runs off from a supply roll 9, which is then laid around the rolling rod 2 by means of rollers or also corresponding nozzles. In an alternative implementation, the lubricant film 8 can first be formed into a tube and subsequently pulled onto or pulled over the rolling rod 2. Lubricant may be applied to a matrix 34 shown in FIG. 6 adapted to the rolling rod 2 and subsequently applied to the rolling rod 2.

(20) In the case of the latter implementations, in particular, it is possible that films having a varying layer thickness are used, so that a varying layer thickness profile of the lubricant layer 15 is directly applied to the rolling rods. In this connection, the application rollers 10 form an apparatus 35 for varying the layer thickness of the lubricant along the rolling rod 2. On the other hand, it is understood that a corresponding profile can also be made available by means of multiple layers that are applied or put on.

(21) As is directly evident, the application rollers 10 bring about the result, in the exemplary embodiment according to FIG. 6, that the lubricant film 8 is pressed onto or pressed down onto the rolling rod 2, thereby making it possible to minimize the risk that lubricant is lost in uncontrolled manner. However, the latter can also be used advantageously in the implementation according to FIG. 5, but also when using a tube, analogously.

(22) However, such mechanical pressing on or pressing down can also be advantageously utilizedin accordance with the exemplary embodiment shown in FIG. 7in the case of fluidic lubricants, for example in the case of dry or at most slightly moistened lubricant powders, but also in the case of a corresponding paste-like material. For this purpose, the fluidic lubricant is applied to an application band 12, for example from a lubricant supply 11; this band runs by way of deflection rolls 13. In this connection, the application band 12 is disposed at a slight incline relative to the movement direction of the rolling rod 2, which rolls over the application band 12, so that the lubricant is pressed onto the rolling rod 2. In this manner, the lubricant can be applied to the rolling rod 2 in targeted and operationally reliable manner, at minimal loss. The layer thickness can be controlled, on the one hand, by means of the speed of the application band 12, by means of the take-off speed from the lubricant supply 11 and/or by means of the slanted position between rolling rod 2 and application band 12.

(23) Flowable lubricant can also, as shown as an example in FIG. 8, be applied to a rolling rod 2 from a supply container 11 by way of a slinger wheel 14, whereby this slinger wheel 14 is preferably provided in an enclosed space, in order to minimize exit of lubricants and contamination of the workplace in this manner. Also in the case of such an embodiment, as is furthermore true for the other aforementioned embodiments, it is possible to measure the lubricant thickness of the lubricant layer 15, in order to thereby adapt the lubricant thickness locally to the desired requirements.

(24) In this connection, it is understood that, in particular also in the implementations according to FIGS. 5, 7, and 8, the lubricant can be mixed with a corresponding functional agent, which has adhesive properties or other properties, in order to promote adhesion to the rolling rod 2. Furthermore, it is understood that in place of a moving application band 12, application rollers that lie against the rolling rod 2, similar to the application rollers 10 of the example of use according to FIG. 6, can be used. Likewise, other or further devices that have a press-down effect, such as nozzle arrangement or link chains or prism chains, can be used accordingly; these can also serve as application devices, if necessary. Also, it is possible to apply the lubricant to the rolling rod 2 by way of brushing.

(25) In the case of a hot-rolling mill 20, as explained as an example in FIG. 9, using a Konti roller train, a perforated hollow block is first dragged to a deoxidation system 23 by way of transverse transport 22. There, loose scale on the interior surface of the hollow block 21 is blown out, and a borate and/or phosphate powder is blown in to dissolve adhering scale. It is understood that depending on the concrete implementation of the present invention, alternative or further measures can be provided at this point.

(26) Subsequently, the hollow block 21 is positioned in front of a corresponding rolling mill 24 (here a longitudinal rolling mill), and a rolling rod 2 coated with lubricant is pushed into the hollow block 21. The latter takes place, in the case of this embodiment, by way of a retention apparatus 25 that positions the rolling rod 2 accordingly and holds it in place also during the subsequent rolling process. In other implementations of the present invention, the rolling rod 2 can rotate freely, without retention, whereby then, preferably, a corresponding positioning device is provided for the roller rod 2, in order to introduce the rod into the hollow block 1 and continue to convey it, if necessary.

(27) After rolling, the rolling rod 2 is retracted and moved out of the roiling line by way of transverse transport 26. After the transverse transport, the rolling rod 2 is conveyed through a cooling device 28, by way of roller conveyors 27, in the case of this exemplary embodiment, and there cooled to the temperature required for subsequent lubrication. Depending on the concrete implementation of the present invention, it is also possible to do without separate cooling, if necessary.

(28) After cooling, the rolling rod 2 is once again transported transversely in a transverse transport 29, and passed to a lubricant application station 30 according to the invention, which is connected, in the case of this exemplary embodiment, with a separate lubricant prefabrication station 33, from which prefabricated lubricant is made available, being kept on hand. In this exemplary embodiment, the hot-rolling mill 20 and the lubricant prefabrication station 33 do not work synchronous with one another, whereby it is understood that in other embodiments, synchronous work or even doing without such separate lubricant prefabrication can be provided, if necessary. The latter lubricant application station 30 can be any one of the application stations described above, or can implement any one of the application methods described above.

(29) After lubrication, the rod is transported to a waiting position, by way of further roller conveyors 31 or by way of a further transverse transport 32, from which position it can be picked up by the retention device 25, if this has been moved back (shown with a dotted line) and introduced into a hollow block 21 that has been made available.

(30) It is understood that such a cycle for rolling rod lubrication can deviate in details from the exemplary embodiment described above, without deviating from the basic idea of the present invention.

(31) FIG. 10 shows a rolling rod lubrication similar to that shown in FIG. 6 but with a lubricant in the form of a sheet 48, e.g. a graphite sheet, being pulled over and then pressed onto the rolling rod 2 longitudinally via the rollers 9 and 10.

(32) FIGS. 11-14 show cross-sectional views through a rolling rod 2 with a lubricant film 8 or a lubricant sheet 48 disposed on the rolling rod 2 and with a functional agent film 37 or a functional agent sheet 37 being disposed between the lubricant film or sheet 8, 48 and the rolling rod 2.

REFERENCE SYMBOL LIST

(33) 1 work piece 2 rolling rod 3 cross-rolling 4 longitudinal rollers 5 transport roller 6 lubricant dispersion 7 nozzle ring 8 lubricant film 9 supply roll 10 application roller 11 lubricant supply 12 application band 13 deflection roll 14 slinger wheel 15 lubricant layer 20 hot-rolling mill 21 hollow block 22 transverse transport 23 deoxidation system 24 rolling mill 25 retention device 26 transverse transport 27 roller conveyor 28 cooling device 29 transverse transport 30 lubricant application station 31 roller conveyor 32 transverse transport 33 lubricant fabrication station