EP3733317B1 - Rolling of a product - Google Patents

Description

The invention relates to a method and a rolling device for rolling a rolling stock with a reversing rolling stand.

In a reversing rolling stand, a rolling stock is alternately guided in two opposite rolling directions through a roll gap between two rotating work rolls in order to reduce the thickness of the rolling stock. The rolling stock is usually a metallic rolled strip. A passage of the rolling stock through the roll gap is referred to as a roll pass. During the first rolling pass, the rolling stock enters the roll gap with a relatively high pickling roughness, which is then further smoothed out with each subsequent rolling pass. The friction of the rolling stock with the work rolls is correspondingly high in the first rolling passes. The consequences are high rolling forces and negative effects of the rolling abrasion on the strip cleanliness of the rolling stock. Excessively high rolling forces may lead to a higher number of rolling passes being required in the reversing rolling stand and thus to longer production times. Excessively high coefficients of friction can also mean that particularly thin products cannot be manufactured at all, since due to the elastic roll deformation, no further reduction in thickness is possible from a certain thickness of the rolling stock. Poor strip cleanliness results in reduced product quality (in the case of a cold-rolled end product) or additional effort in the subsequent processing steps (in the case of an annealed and/or galvanized end product). In order to reduce the friction between the rolling stock and the work rolls, the roll gap is usually lubricated. Also, the work rolls are typically cooled to reduce the temperature and wear of the work rolls.

EP 2 651 577 B1 discloses a method and apparatus for applying a lubricant when rolling a metallic rolled strip, which is guided through a roll gap between two work rolls. In this case, a mixture of the lubricant and a carrier gas is produced in an atomization device, and the mixture is applied to the surface of at least one work roll and/or to the surface of the rolled strip using spray nozzles.

EP 3 092 088 B1 discloses a method and apparatus for applying a lubricating oil when rolling a metal flat stock in a rolling mill. For this purpose, the lubricating oil is atomized by means of compressed air to form an aerosol, which is sprayed onto the rolling stock and/or at least one roll of the roll stand by means of a plurality of spray nozzles arranged next to one another.

WO 2013/029886 A1 discloses operating methods for a reversing rolling mill with at least one reversing rolling stand for rolling a rolling stock, the rolling stock passing through the at least one reversing rolling stand in a sequence of passes with changing throughput direction. After each pass, before coiling, pure rolling oil without water is applied to the rolling stock by means of a rolling oil application device arranged between the reversing rolling stand and the respective coiler. The rolling oil can be atomized in the form of an oil-air mixture evenly over the entire width of the rolling stock. Cooling is independent of the application of rolling oil, with pure water being discharged onto the rolls of the reversing mill from a cooling device arranged on one side of the reversing mill, so that the rolling oil application and the water application take place on the same side of the reversing mill for every second rolling pass.

The invention is based on the object of specifying an improved method and an improved rolling device for rolling a rolling stock with a reversing rolling stand.

The object is achieved according to the invention by a method having the features of claim 1 and a rolling device having the features of claim 10 .

Advantageous configurations of the invention are the subject matter of the dependent claims.

In the method according to the invention for rolling a rolling stock, the rolling stock is guided alternately in two opposite rolling directions through a roll gap between two work rolls of a reversing roll stand. A lubricant, for example a lubricating oil, is introduced into a contact zone in which the rolling stock is in contact with the work rolls to lubricate the contact zone, and a coolant is applied to the rolling stock and/or the work rolls. The lubricant is dispensed in a mixture with a carrier gas, with the mixture being applied exclusively to the work rolls and/or to the Rolled stock is sprayed. The coolant is discharged onto the work rolls and/or onto the rolling stock exclusively on an entry side of a rolling pass, on which the rolling stock enters the roll gap. Since every two consecutive rolling passes have different rolling directions, the entry side of a rolling pass is a side of the reversing mill, which is the exit side of the following rolling pass, and the exit side of a rolling pass is a side of the reversing mill, which is the entry side of the following rolling pass.

In other words, the invention provides for rolling stock to be lubricated with a lubricant only on the outlet side during rolling in a reversing rolling mill and to be cooled with a coolant only on the inlet side, with the lubricant being applied in a mixture (aerosol) with a carrier gas to the work rolls and/or the rolling stock is sprayed. Preferably, the lubricant is only applied to the work rolls because less lubricant is carried out of the reversing mill stand, which reduces lubricant consumption. The application of the lubricant by spraying the work rolls and/or the rolling stock with a mixture of the lubricant and a carrier gas has the advantage, for example compared to the application of a lubricating emulsion, that the lubricant is only applied very specifically to certain surface areas of the work rolls and/or the rolling stock can be applied in order to concentrate the lubricant application on the contact zone in which the rolling stock is present in the nip on the work rolls. In this way, in particular, the lubrication can be reduced to a minimum quantity lubrication (so-called minimum quantity lubrication) with a minimal amount of lubricant.

The only entry-side dispensing of coolant on the work rolls and / or on the rolling stock prevents larger amounts of coolant are carried out the outlet side of the reversing mill, which is precisely at higher rolling speeds of the rolling stock due to the Mass inertia of the coolant can occur. The only spraying of the work rolls and/or the rolling stock on the outlet side with the mixture of the lubricant and the carrier gas takes into account that with spraying on the inlet side and simultaneous dispensing of coolant on the inlet side on the work rolls and/or on the rolling stock, the coolant can prevent the mixture from the lubricant and the carrier gas reaches the work rolls and/or the rolling stock. This exploits the fact that lubricant that is applied by spraying the work rolls and/or the rolling stock with the mixture of the lubricant and the carrier gas adheres better to the work rolls and/or the rolling stock than, for example, a lubricant that is applied with an emulsion so that no lubricant is required on the inlet and outlet side, since lubricant applied on the outlet side also acts on the inlet side due to its adhesion.

Water or a cooling emulsion, for example, is used as the coolant. The cooling emulsion contains, for example, a rolling oil with a proportion of less than ten percent by volume of the cooling emulsion. Furthermore, the coolant can contain at least one emulsifier, which prevents the components (for example water and rolling oil) of the cooling emulsion from segregating and improves adhesion of the lubricant to the work rolls and/or to the rolling stock. Using pure water as a coolant has the advantage over using a cooling emulsion that the temperature of the coolant can be kept lower than with emulsion cooling (a cooling emulsion requires a certain minimum temperature), which improves the cooling effect. In addition, with pure water cooling, there is no effort (installation, ongoing operating costs) for the production and recycling of the cooling emulsion. By adding an emulsifier that prevents the lubricant from sticking to the work rolls and/or improved on the rolling stock, the need for lubricant can advantageously be further reduced.

Furthermore, it can be provided that the mixture of the lubricant and the carrier gas is sprayed onto the work rolls and/or onto the rolling stock in one of the two rolling directions only when the rolling stock is being passed through the roll gap. As a result, spray bars need only be arranged on one side of the reversing mill stand to dispense the mixture.

Alternatively, it can be provided that the mixture of the lubricant and the carrier gas is sprayed onto the work rolls and/or onto the rolling stock in both rolling directions when the rolling stock is passed through the roll gap. This requires spray bars for discharging the mixture on both sides of the reversing mill stand, but allows for more flexible lubrication, since lubricant can be applied to the work rolls and/or the rolling stock on the outlet side for any rolling pass.

Furthermore, it can be provided that when the rolling stock is passed through the roll gap for the first time (i.e. during the first rolling pass), a rolling stock head of the rolling stock, which is guided as the first area of the rolling stock through the roll gap, at a lower speed than the remaining area of the rolling stock through the Roll gap is performed. Furthermore, it can be provided that no coolant is discharged onto the work rolls and/or onto the rolling stock when the rolling stock head is passed through the roll gap for the first time. In this embodiment of the invention, the slower passage of the head of the rolling stock through the roll gap during the first pass does not result in such a great need for cooling as when it is passed through at a higher speed. As a result, cooling during the threading of the rolling stock into the reversing rolling stand can be dispensed with. As a rule, this does not pose a problem, since the rolling stock head is usually of reduced quality anyway and is therefore scrapped.

• ein Reversierwalzgerüst mit zwei Arbeitswalzen,
• wenigstens einen Sprühbalken, der dazu eingerichtet ist, das Gemisch aus dem Schmiermittel und dem Trägergas auf eine Arbeitswalze oder/und auf das Walzgut zu sprühen,
• wenigstens einen Kühlbalken, der dazu eingerichtet ist, das Kühlmittel auf eine Arbeitswalze oder/und auf das Walzgut auszugeben, und
• eine Steuereinheit, die dazu eingerichtet ist, jeden Sprühbalken und jeden Kühlbalken derart zu steuern, dass das Gemisch aus dem Schmiermittel und dem Trägergas ausschließlich auf einer Auslaufseite eines Walzstichs und das Kühlmittel ausschließlich auf einer Einlaufseite eines Walzstichs ausgegeben wird.

A rolling device according to the invention for carrying out the method according to the invention

• a reversing mill stand with two work rolls,
• at least one spray bar, which is set up to spray the mixture of the lubricant and the carrier gas onto a work roll and/or onto the rolling stock,
• at least one cooling beam, which is set up to discharge the coolant onto a work roll and/or onto the rolling stock, and
• a control unit configured to control each spray bar and each cooling bar in such a way that the mixture of the lubricant and the carrier gas is discharged exclusively on an outlet side of a rolling pass and the coolant is exclusively discharged on an inlet side of a rolling pass.

A rolling device according to the invention makes it possible to carry out the method according to the invention. The advantages of a rolling device according to the invention therefore correspond to the advantages of the method according to the invention already mentioned above.

In one embodiment of the rolling device, all the spray bars are arranged on the same side of the reversing rolling stand. Compared to an arrangement of spray bars on both sides of the reversing rolling stand, this configuration of the rolling device saves space, effort and costs and takes into account that due to the good adhesion of the lubricant to the work rolls and/or to the rolling stock, as already discussed above, lubrication with each rolling pass usually can be omitted.

In a further embodiment of the rolling device, at least one spray beam and at least one cooling beam are arranged on at least one side of the reversing rolling stand.

In a further embodiment of the rolling device, at least one spray bar is arranged on at least one side of the reversing rolling stand above a rolling stock level in which the rolling stock is guided, and at least one spray bar is arranged below the rolling stock level. Furthermore, at least one cooling beam can be arranged above the rolling stock level and at least one cooling beam below the rolling stock level on at least one side of the reversing rolling stand. These refinements of the rolling device advantageously enable the work rolls and/or the rolling stock to be lubricated and/or cooled on both sides of the rolling stock.

• FIG 1 schematisch eine Seitenansicht eines ersten Ausführungsbeispiels einer erfindungsgemäßen Walzvorrichtung,
• FIG 2 schematisch eine Seitenansicht eines zweiten Ausführungsbeispiels einer erfindungsgemäßen Walzvorrichtung.

The properties, features and advantages of this invention described above, and the manner in which they are achieved, will become clearer and more clearly understood in connection with the following description of exemplary embodiments, which will be explained in more detail in connection with the drawings. show:

• FIG 1 schematically a side view of a first embodiment of a rolling device according to the invention,
• FIG 2 schematically a side view of a second embodiment of a rolling device according to the invention.

Corresponding parts are provided with the same reference symbols in the figures.

figure 1 shows a schematic side view of a first exemplary embodiment of a rolling device 1 according to the invention for rolling a rolling stock 2. The rolling stock 2 is a metallic rolled strip, for example a steel strip, the thickness of which is reduced by rolling. The rolling device 1 comprises a reversing rolling stand 3, two spray bars 5, 6, four cooling bars 9 to 12 and a control unit 27.

The reversing mill stand 3 has two work rolls 23, 24 arranged one above the other and two back-up rolls 25, 26, one back-up roll 25 being arranged above the two work rolls 23, 24 and the other back-up roll 26 being arranged below the two work rolls 23, 24. The two work rolls 23, 24 are spaced apart from one another by a roll gap 17.

To roll the rolling stock 2, the work rolls 23, 24 are rotated and the rolling stock 2 is alternately guided through the roll gap 17 by the rotating work rolls 23, 24 in two opposite rolling directions. In figure 1 a rolling pass is shown in which the rolling stock 2 is guided from left to right through the roll gap 17, so that the left side of the reversing mill stand 3 is the entry side of the rolling pass and the right side of the reversing mill stand 3 is the exit side of the rolling pass. In the subsequent rolling pass, the rolling stock 2 is guided from right to left through the roll gap 17, so that the right-hand side of the reversing rolling stand 3 is the entry side of the rolling pass and the left-hand side of the reversing rolling stand 3 is the exit side of the rolling pass.

The spray bars 5, 6 are arranged on one side of the reversing rolling stand 3, one spray bar 5 being arranged above a rolling stock plane 19 in which the rolling stock 2 is guided, and the other spray bar 6 being arranged below the rolling stock plane 19. Each spray bar 5, 6 is set up to spray a mixture 20 (aerosol) of a lubricant 21, for example a lubricating oil, and a carrier gas onto the surface of a work roll 23, 24. To produce the mixture 20, each spray bar 5, 6 has an atomizing device, not shown in detail, to which the lubricant 21 and the carrier gas are supplied and which atomizes the lubricant 21 in the carrier gas. Neither does each spray bar 5, 6 have the mixture 20 for dispensing spray nozzles shown in more detail, which are designed to spray the mixture 20 onto the surface of a work roll 23, 24.

The cooling beams 9 to 12 are arranged on both sides of the reversing rolling stand 3, with a cooling beam 9, 11 being arranged above the rolling stock level 19 on each side of the reversing rolling stand 3 and a cooling beam 10, 12 being arranged below the rolling stock level 19. Each cooling beam 9 to 12 is set up to emit a coolant 22 onto a surface of a work roll 23, 24 and/or a surface of the rolling stock 2. For this purpose, each cooling bar 9 to 12 has, for example, spray nozzles, not shown in detail, through which the coolant 21 can be discharged. The coolant 22 is, for example, water or a cooling emulsion containing water and a rolling oil, the oil content of the cooling emulsion being less than ten percent by volume. Furthermore, the coolant 22 can contain at least one emulsifier, which improves adhesion of the lubricant 21 to the work rolls 23, 24 and/or to the rolling stock 2.

The spray bars 5, 6 and the cooling bars 9 to 12 can be controlled by the control unit 27. The control unit 27 is set up to control the spray bars 5, 6 and the cooling bars 9 to 12 in such a way that the mixture 20 is sprayed onto the work rolls 23, 24 exclusively on the outlet side of a rolling pass and the coolant 22 is sprayed exclusively on the inlet side of a rolling pass onto the work rolls 23, 24 and/or onto the rolling stock 2. Since at the in figure 1 In the exemplary embodiment shown, the spray bars 5, 6 are only arranged on one side of the reversing rolling stand 3, in this exemplary embodiment the mixture 20 is therefore only sprayed onto the work rolls 23, 24 at most every second rolling pass.

Preferably, in the first rolling pass, a rolling stock head of the rolling stock 2, which is the first area of the Rolling stock 2 is guided through the roll gap 17 at a lower speed than the remaining area of the rolling stock 2 through the roll gap 17 and when the rolling stock head is passed through the roll gap 17 for the first time, no coolant 22 is applied to the work rolls 23, 24 and/or to the Rolling stock 2 issued.

figure 2 shows a schematic side view of a second exemplary embodiment of a rolling device 1 according to the invention for rolling a rolling stock 2. This exemplary embodiment differs from that in figure 1 shown first embodiment only by the number and arrangement of spray bars 5 to 8. In the second embodiment, on each side of the reversing rolling stand 3 are a spray bar 5, 7 and a cooling bar 9, 11 above the rolling stock plane 19 and a spray bar 6, 8 and a cooling bar 10, 12 are arranged below the plane 19 of the rolling stock.

Analogously to the first exemplary embodiment, the control unit 27 is set up to control the spray bars 5 to 8 and the cooling bars 9 to 12 in such a way that the mixture 20 is sprayed onto the work rolls 23, 24 exclusively on the outlet side of a rolling pass and the coolant 22 exclusively is discharged onto the work rolls 23, 24 and/or onto the rolling stock 2 on an entry side of a rolling pass. Since at the in figure 2 shown embodiment spray bar 5 to 8 are arranged on both sides of the reversing mill stand 3, in contrast to the in figure 1 In the embodiment shown, the mixture 20 is sprayed onto the work rolls 23, 24 at each rolling pass. In figure 2 is like in figure 1 a rolling pass is shown, in which the rolling stock 2 is guided from left to right through the roll gap 17, so that the entry side of the rolling pass is the left-hand side of the reversing rolling stand 3 and the exit side of the rolling pass is the right-hand side of the reversing rolling stand 3. Accordingly, the work rolls 23, 24 in this rolling pass only from the right spray beams 5, 6 arranged by the reversing roll stand 3 are sprayed with the mixture 20 and the coolant 22 is only discharged from the cooling beams 11, 12 arranged to the left of the reversing roll stand 3 onto the work rolls 23, 24 and/or the rolling stock 2.

Although the invention has been illustrated and described in detail by means of preferred embodiments, the invention is not limited by the disclosed examples and other variations can be derived therefrom by a person skilled in the art without departing from the protective scope of the invention as defined by the claims.

Reference List

1

rolling device

2

rolling stock

3

reversing mill stand

5 to 8

spray bar

9 to 12

chilled beam

17

roll gap

19

rolling stock level

20

mixture

21

lubricant

22

coolant

23, 24

stripper

25, 26

backup roll

27

control unit

Claims (14)

1. Method for rolling a rolling stock (2), wherein

   - the rolling stock (2) is guided alternatingly in two opposite rolling directions through a rolling gap (17) between two working rollers (23, 24) of a reversing rolling stand (3),

   - a lubricant (21) for lubricating a contact zone is introduced into the contact zone, in which the rolling stock (2) bears against the working rollers (23, 24),

   - and a coolant (22) is applied to the working rollers (23, 24) or/and to the rolling stock (2), wherein

   - the lubricant (21) is dispensed in a mixture (20) with a carrier gas, wherein the mixture (20) is sprayed onto the working rollers (23, 24) or/and onto the rolling stock (2) exclusively on a run-out side of a rolling pass, on which run-out side the rolling stock (2) runs out of the rolling gap (17),

   - and the coolant (22) is dispensed onto the working rollers (23, 24) or/and onto the rolling stock (2) exclusively on a run-in side of a rolling pass, on which run-in side the rolling stock (2) runs into the rolling gap (17).
2. Method according to Claim 1, wherein the lubricant (21) is a lubricating oil.
3. Method according to Claim 1 or 2, wherein water is used as coolant (22).
4. Method according to Claim 1 or 2, wherein a cooling emulsion is used as coolant (22).
5. Method according to Claim 4, wherein the coolant (22) contains at least one emulsifier, which improves adhesion of the lubricant (21) to the working rollers (23, 24) or/and to the rolling stock (2).
6. Method according to one of the preceding claims, wherein the mixture (20) of the lubricant (21) and the carrier gas is sprayed onto the working rollers (23, 24) or/and onto the rolling stock (2) only when the rolling stock (2) is passing through the rolling gap (17) in one of the two rolling directions.
7. Method according to one of Claims 1 to 5, wherein the mixture (20) of the lubricant (21) and the carrier gas is sprayed onto the working rollers (23, 24) or/and onto the rolling stock (2) when the rolling stock (2) is passing through the rolling gap (17) in both rolling directions.
8. Method according to one of the preceding claims, wherein, when the rolling stock (2) is passing through the rolling gap (17) for the first time, a rolling-stock head of the rolling stock (2), which is the first region of the rolling stock (2) to be guided through the rolling gap (17), is guided through the rolling gap (17) at a slower speed than the remaining region of the rolling stock (2).
9. Method according to Claim 8, wherein, when the rolling-stock head is passing through the rolling gap (17) for the first time, no coolant (22) is dispensed onto the working rollers (23, 24) or/and onto the rolling stock (2).
10. Rolling apparatus (1) for carrying out the method according to one of the preceding claims, the rolling apparatus (1) comprising:

    - a reversing rolling stand (3) with two working rollers (23, 24),

    - at least one spraying bar (5 to 8), which is configured to spray the mixture (20) of the lubricant (21) and the carrier gas onto a working roller (23, 24) or/and onto the rolling stock (2),

    - at least one cooling bar (9 to 12), which is configured to dispense the coolant (22) onto a working roller (23, 24) or/and onto the rolling stock (2), and

    - a control unit (27), which is configured to control each spraying bar (5 to 8) and each cooling bar (9 to 12) in such a way that the mixture (20) of the lubricant (21) and the carrier gas is dispensed exclusively on a run-out side of a rolling pass and the coolant (22) is dispensed exclusively on a run-in side of a rolling pass.
11. Rolling apparatus (1) according to Claim 10, wherein all the spraying bars (5, 6) are arranged on the same side of the reversing rolling stand (3).
12. Rolling apparatus (1) according to Claim 10 or 11, wherein at least one spraying bar (5 to 8) and at least one cooling bar (9 to 12) are arranged on at least one side of the reversing rolling stand (3).
13. Rolling apparatus (1) according to one of Claims 10 to 12, wherein, on at least one side of the reversing rolling stand (3), at least one spraying bar (5, 7) is arranged above a rolling-stock plane (19), in which the rolling stock (2) is guided, and at least one spraying bar (6, 8) is arranged below the rolling-stock plane (19).
14. Rolling apparatus (1) according to one of Claims 10 to 13, wherein, on at least one side of the reversing rolling stand (3), at least one cooling bar (9, 11) is arranged above a rolling-stock plane (19), in which the rolling stock (2) is guided, and at least one cooling bar (10, 12) is arranged below the rolling-stock plane (19).

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