RU2774690C1 - Method for cold rolling aluminum product and associated cold rolling plant - Google Patents

Abstract

FIELD: aluminum products.

SUBSTANCE: method for cold rolling an aluminum product, such as a sheet, through at least one rolling stand (1), in which a lubricant is applied to the product in the vicinity of said at least one rolling stand (1) using first application means (2), wherein said lubricant contains an emulsion of oil and water. A corresponding rolling plant is also described.

EFFECT: rolling process of products made of aluminum or its alloys, in particular sheets, is carried out with increased lubrication efficiency, increased ability to remove heat generated during plastic deformation, increased safety of the working environment and simplified lubrication management, including after the rolling operation, as well as in obtaining stable the integrity of the thin film of lubricant in the rolling department, to avoid direct contact between the work rolls and the aluminum product.

11 cl, 4 dwg

Description

The field of technology to which the invention belongs

The present invention relates to a cold rolling process specifically for rolling aluminum or aluminum alloy products, in particular sheets, and to a related cold rolling plant.

State of the art

Friction is one of the key parameters in the processes of plastic deformation of metal products. Lubrication plays an important role in the final aspect of the metal surface, especially in cold working: in particular in the case of cold-rolled products made of aluminum or its alloys, such as, for example, sheets.

At present, kerosene is widely used as a lubricant in industrial aluminum cold rolling mills, which does not leave marks on the surface of rolled sheets that affect the quality of such a surface. On the other hand, handling kerosene is a difficult and dangerous task, primarily due to the risk of fire and the risk to the health of operators. The kerosene also needs to be filtered to separate the aluminum powder and waste generated from the rolling process, and filtering is a complex and costly process.

Therefore, the disadvantages of kerosene mainly include:

- significant fire risk and related social costs, insurance costs and costs associated with production downtime;

- reducing the ability to remove heat generated during plastic deformation;

- characteristic toxicity (given that it is a by-product of oil);

- a complex control process also outside the rolling stand (it must be transported, filtered and distilled).

In more detail, the use of kerosene involves:

- the use of an expensive carbon dioxide fire extinguishing system, which in turn involves the removal of CO ₂ from the working area for the safety of the operator;

- the obligation of operators near the machine to always carry an oxygen bottle with them, since the carbon dioxide fire extinguishing system will saturate the atmosphere surrounding the machine in the event of a fire;

- the presence of vapors and aerosols that have a negative impact on human health and the environment;

- high costs for the lubrication itself, given that the cost of kerosene today exceeds 1 euro per liter, and on average a rolling mill consumes about several hundred thousand liters of kerosene per year.

In this regard, it is extremely important to rethink and redesign the technology of cold rolling of aluminum products and obtain a safe technology that does not have a negative impact on the environment and reduces costs.

Moreover, during cold rolling of aluminum sheets, it is not always possible to ensure the integrity of the thin film of lubricant (several hundred millimeters) in the rolling department, which serves to prevent direct contact between the work rolls and the formation of defects on the surface of the material. One such method and associated apparatus are described in JPH07132314A and correspond to the preamble of claims 1 and 5, respectively.

Therefore, there is a need to create an innovative method and associated apparatus, which will overcome the above disadvantages.

Disclosure of invention

The first objective of the present invention is to provide a rolling process for products made of aluminum or its alloys, in particular sheets, with increased lubrication efficiency, increased ability to remove heat generated during plastic deformation, increased safety of the working environment and simplified lubrication management, including after the rolling operation.

Another object of the invention is to provide a rolling process for products made of aluminum or its alloys, which makes it possible to consistently achieve the integrity of a thin film of lubricant in the rolling department in order to avoid direct contact between the work rolls and the aluminum product.

An additional object of the invention is to provide a suitable rolling plant for more efficient rolling of products made of aluminum or its alloys.

Thus, the present invention aims to achieve at least one of the above objects by providing a process for cold rolling a product made of aluminum or its alloys, which provides at least one rolling stand and in which a lubricant, which is an emulsion of oil and water, is applied near the specified at least one rolling stand using several first application means, while

Δv = v _s – v _r is the difference between the feed rate v _s of the rolled stock measured at the exit of at least one rolling stand and the circumferential speed v _r of the work rolls of said at least one rolling stand measured during the rolling operation,

and Δv ₀ = v _s0 - v _r0 is the calculated value of the specified difference,

and each time when the relation [(δv * v _r0 )/(v _r * Δv ₀ )] - 1 < L, where L is equal to a value from 0.0005 to 0.002, is not satisfied, before the specified at least one rolling stand, with taking into account the direction of supply of the product, only oil is applied to the aluminum product by means of several second application means until the indicated ratio is fulfilled again.

In addition, the present invention provides an installation for rolling products from aluminum or its alloys, configured to carry out the above rolling method, which contains:

- at least one rolling stand;

- several first means of application, located near the specified at least one rolling stand and made with the possibility of applying an emulsion of oil and water on the product;

and which provides

first sensors for detecting first data, the first data being values of the feed rate v _s of the rolled product exiting at least one rolling stand;

- second sensors for detecting second data, the second data being values of peripheral speed v _r of the work rolls of at least one rolling stand;

- second application means located near said at least one rolling stand and configured to apply only oil to the product;

- a control system configured to:

- receive said first data and said second data,

- calculate the difference Δv = v _s – v _r ,

- check whether the ratio [(δv * v _r0 )/(v _r * Δv ₀ )] – 1 < L, where Δv ₀ = v _s0 – v _r0 is the calculated value of the specified difference and L is the value in the range from 0, 0005 to 0.002,

and, if said ratio is not met, actuating said second application means.

The solution in accordance with the present invention has significant advantages, while completely eliminating the risk of fire and significantly reducing the complexity of lubricant management. The water-based emulsion's ability to remove heat is more than twice that of kerosene, and hence the required flow rates are lower for the same performance.

Other advantages in accordance with the present invention include:

- use of more accessible lubricant;

- the use of a water-based emulsion with greater lubricity compared to traditional technologies, with a subsequent improvement in rolling processes and the quality of rolled aluminum;

- elimination of surface defects on aluminum, which is a quality problem that occurs after the rolling process, which is well known in the production of aluminum products such as sheets;

- increasing the cooling capacity, which allows rolling at higher speeds, thereby increasing the productivity of the rolling mill;

- increasing the productivity of the rolling mill without the risk of fires (an average of two fires per year);

- does not require an expensive carbon dioxide fire extinguishing system;

- for the operation of the rolling mill, a smoke purification device is not required;

- increasing the compactness of the installation.

Considering also the lower costs associated with insurance, maintenance and increased utilization due to the elimination of the risk of fire, a 10% reduction in operating costs can be expected compared to using kerosene.

In addition, this technology using a water-based emulsion can be implemented on already existing operating plants with minimal modifications associated only with the replacement of the filter block in the exhaust ventilation system, bypassing the evaporator, and with improving the product drying system, if necessary. The rest of the setting can remain unchanged.

The invention advantageously comprises a closed loop control system which, by measuring the advance, i.e. the difference between the speed of the rolled sheet, measured at the exit of at least one rolling stand, and the circumferential speed of the work rolls, measured during rolling, determines whether oil needs to be added to the rolled product, and, if confirmed, applies only oil to the product in front of the rolling department, taking into account the direction of supply of the product itself. This dynamic correction of the amount of lubricant applied to the sheet surface, just before each rolling stand, always ensures the integrity of the thin film of lubricant in the rolling department, thus avoiding direct contact between the work rolls and the aluminum product.

The dependent claims describe preferred embodiments of the invention.

Brief description of the drawings

Additional features and advantages of the invention will become more apparent in view of the detailed description of preferred, but not exclusive, embodiments of the rolling process and associated apparatus, disclosed by way of non-limiting examples, with the help of the accompanying drawings, in which:

in FIG. 1 shows a flow diagram associated with a system for dynamically controlling a lubricant layer on a rolled product;

in FIG. 2 shows a diagram of an installation according to the invention;

in FIG. 3 shows a first embodiment of a part of a plant according to the invention;

in FIG. 4 shows a second embodiment of a part of a plant according to the invention.

The same reference numbers in the figures refer to the same elements or components.

Implementation of the invention

The method of rolling products made from aluminum or aluminum alloys, in accordance with the present invention, provides that an aluminum product, for example, a sheet, crosses at least one rolling stand 1 to obtain a rolled product, while in the vicinity of said at least one rolling stand 1 , with the help of several first application means 2 in front of the rolling department, taking into account the direction of supply of the product itself, a lubricant is applied to the product.

The lubricant preferably contains or consists of an emulsion of oil and water. Some additives may optionally be included in the emulsion.

In addition, if necessary, a dynamic correction of the amount of lubricant applied directly in front of at least one rolling stand is provided, always taking into account the direction of supply of the product itself.

In particular, Δv = v _s - v _r is the difference between the feed rate v _s of rolled products measured at the exit of at least one rolling stand 1, preferably directly at the exit of the rolling stand, and the circumferential speed v _r of the work rolls 3 indicated at least one rolling stand 1 measured during the rolling operation,

and Δv ₀ = v _s0 - v _r0 is the calculated value of said difference, i.e. the difference between the theoretical feed speed v _s0 of the rolled product exiting at least one rolling stand 1, preferably directly at the exit of the rolling stand, and the theoretical circumferential speed v _r0 work rolls 3 of said at least one rolling stand 1,

and each time when the ratio [(Δv * v _r0 )/(v _r * Δv ₀ )] - 1 < L, where L is equal to a value from 0.0005 to 0.002, is not satisfied, before the specified at least one rolling stand, with taking into account the direction of supply of the product, by means of several second application means 6, only oil is applied to the aluminum product until the indicated ratio is fulfilled again.

Preferably, the oil used to dynamically adjust the amount of lubricant to maintain a constant thin film of lubricant, that is, the thin gap occupied by the lubricant located between the surface of the sheet and the surface of the work roll, is the same oil used in the water-based emulsion.

Preferably, but not necessarily, the value of L may be equal to 0.001.

The feed rate v _s of the rolled product is measured, for example, using the first sensors 4 to obtain the first data. By way of example, such first sensors 4 may be laser flow meters, photocells or tachometer wheels.

The circumferential speed v _r of the work rolls 3 is measured, for example, using the second sensors 5 to obtain second data. For example, such second sensors 5 may be sensors for an electric motor that moves the work rolls themselves. The circumferential speed v _r can preferably be measured using the rotational speed of the motor that moves the work rolls, taking into account the possible gear ratio between the transmission and the work rolls.

The feed rate v _s and peripheral speed v _r can be determined substantially continuously, for example every 5-15 ms, preferably every 10 ms.

The theoretical feed speed v _s0 and the theoretical circumferential speed v _r0 are easily calculated in a known manner by those skilled in the art, and for this reason their calculation is not described here. In general, starting from some initial design data, such as, for example, the thickness of the plate at the entry and exit of the rolling stand, the mechanical characteristics of the material, the tensile forces applied to the plate, the theoretical feed speed v _s0 and the theoretical circumferential speed v _r0 and, therefore, advance and coefficient of friction are easily calculated. It is worth noting that the original data is easy to find and is available in the documentation that all manufacturers should have in order to manage the installation.

The control system 20, preferably closed loop, receives first data, ie v _s values, and second data, ie v _r values; checks whether the specified ratio is met, and if the specified ratio is not met, temporarily activates the second application means 6 until the specified ratio is performed again.

The reception of the first and second data and the verification of the relationship may be carried out almost continuously, for example every 5-15 ms, preferably every 10 ms.

In order to better explain the method of the above dynamic correction of the amount of lubricant, it is worth noting that lead is a phenomenon in which the product, preferably a sheet, at the exit from the rolling department has a feed speed v _s that is greater than the circumferential speed v _r of the work rolls.

The advance "fs" is defined as follows:

When substituting the index "0" for the calculated (or theoretical) speed values, the following is similarly determined:

Thus, the control system evaluates the ratio:

As shown in the block diagram in FIG. 1, if this ratio exceeds a predetermined threshold set in the range of 0.05 to 0.2%, for example 0.1%, then the control system sends a command to the second application means 6 to apply additional oil. As such, the deviation between measured values (no index) and calculated values (index "0") should be consistently low. If, for example, the detected sheet feed speed is much higher than the calculated speed, it is likely that the thin film of lubrication is broken in certain areas of the rolling department and, accordingly, there is a problem of contact of the work rolls with the aluminum product. To eliminate this undesirable circumstance, the system introduces clean oil to restore a thin layer of lubrication. This application of pure oil should be considered as occasional (it may be done in transitional steps) and short in relation to the entire rolling process. Mostly, it is performed in a few moments to avoid potentially dangerous circumstances. The application of pure oil lasts until the ratio is satisfied again.

[(Δv * v _r0 )/(v _r * Δv ₀ )] - 1 < L.

The oil and water emulsion is preferably contained in a first tank 7 which supplies the first application means 2, and in said first tank the emulsion is optionally mixed with at least one mixing device 21.

The following is a description of an embodiment of a rolling plant with the possibility of performing the method described above.

On FIG. 2 shows an installation for rolling products from aluminum or aluminum alloy, which contains:

- at least one rolling stand 1;

- several first application means 2 located near said at least one rolling stand and configured to apply an oil and water emulsion to the product, for example sheet 13.

Preferably also provided:

- first sensors 4 for detecting first data, the first data being the values of the feed rate v _s of the rolled product coming out of at least one rolling stand 1;

second sensors 5 for detecting second data, said second data being peripheral speeds v _r of work rolls 3 of said at least one rolling stand 1;

a plurality of second application means 6 located in the vicinity of said at least one rolling stand and configured to apply only oil to the article;

- a control system configured to:

- receive said first data and said second data,

- calculate the difference Δv = v _s - v _r ,

- check if the ratio [(Δv * v _r0 )/(v _r * Δv ₀ )] - 1 < L, where L is a value from 0.0005 to 0.002,

- and, if the specified ratio is not met, actuate the specified second means of application 6.

Optionally, the first reservoir 7 contains the emulsion and supplies it to the first application means 2, preferably by means of a first dosing device 10 located between the reservoir 7 and the application means 2.

A second reservoir 8 can also be provided, which contains only oil and, on command from the control system, supplies it to the second application means 6, optionally with the help of a second dosing device 9, located between the reservoir 8 and the application means 6.

At least one mixing device 21 can be provided inside the tank 7 and/or inside the tank 8.

Preferably, at least one solenoid valve 14 is provided between the emulsion reservoir 7 and the application means 2, or between the metering device 10 and the application means 2.

Similarly, at least one solenoid valve 15 may be provided between the oil reservoir 8 and the application means 6, or between the metering device 9 and the application means 6.

Solenoid valve 15 and/or solenoid valve 14 are controlled by control system 20.

The oil application means 6 can always be loaded with oil, if required, so that when actuated by the control system 20 by means of the solenoid valve 15, they supply a predetermined amount of oil.

In a preferred embodiment of the invention, drying means 11 are provided, placed behind at least one rolling stand 1, taking into account the direction of the product feed, and in front of the winder 12. Such drying means 11 are designed to remove water from the rolled product. For example, at least one CJD (limited jet dryer) dryer capable of delivering at least one jet of compressed air in a direction opposite to that of the aluminum product may be used.

In the case of a single rolling stand 1, this can advantageously be a reversing stand located between the two winders 16 and the product unwinder 12 in the feed direction of the rolled product. In this case, the application means 2 and the application means 6 are located on both sides of the rolling stand 1 along the product feed direction, preferably both above and below the product feed plane (FIG. 3). The drying means 11 may be located between each winder 16, 12 and the rolling stand 1.

If the rolling stand 1 worked in only one direction, the application means 2 and the application means 6 would be located only on the side of the aluminum product feed into the rolling stand 1, preferably both above and below the product delivery plane. In this case, the drying means 11 will only be located between the rolling stand 1 and the winder 12, with the rolling stand located between the unwinder 16 and the winder 12.

Similarly, if at least two rolling stands 1 were provided one behind the other, the configuration known as the "tandem" mill, both the application means 2 and the application means 6 would be located only on the supply side of each rolling stand, preferably both above and below the product delivery plane. Alternatively, in the embodiment shown in FIG. 4, a plurality of reversible rolling stands 1 are provided, wherein application means 2 and application means 6 are located on both sides of each rolling stand 1 along the direction of product infeed, preferably both above and below the plane of product infeed (see FIG. 4).

More generally, the control system 20 can be equally applied to "four" stands (also known as 4-Hi), "six" stands (6-Hi) and cluster stands ("Sendizimir mill") in a configuration with 12 or 20 swaths (12-Hi and 20-Hi respectively). While the first two types of rolling stands can be grouped, resulting in tandem mills, cluster stands are always made separately.

In some embodiments of the invention, preferably, the application means 6 are located in a position that is close to the work rolls 3 of the rolling stand 1, but removed from the plane of the product feed relative to the application means 2. Similarly, the application means 2 are located in a position remote from the work rolls 3, but close to the product delivery plane in relation to the application means 6.

For example, the distance between the application means 6 and the vertical plane containing the axes of rotation of the work rolls of the corresponding rolling stand is between D/4 and 3D, preferably between D/3 and 2D, where D is the diameter of the work rolls 3; while the distance between said application means 6 and the product delivery plane is between D/10 and D/2, preferably between D/5 and D/3.

Optionally, the distance between the application means 2 and the vertical plane containing the axes of rotation of the work rolls of the respective rolling stand is between D/3 and 4D, preferably between D/2 and 3D; while the distance between said application means 2 and the product delivery plane is between D/10 and D/2, preferably between D/8 and D/4.

However, in other embodiments of the invention, the application means 6 are located in a position remote from the work rolls 3 of the rolling stand 1, but near the product feed plane, while the application means 2 are located near the work rolls 3, but removed from the product feed plane. The distance ranges mentioned in the previous paragraph can be considered inverse.

By way of example, both the application means 2 and the application means 6 comprise or consist of injection devices, for example contain rows of nozzles, which preferably extend across the width of the aluminum product, i.e. transverse to the plane of delivery of the product.

Claims (28)

1. The method of cold rolling an article made of aluminum or aluminum alloys through at least one rolling stand (1), in which the product is lubricated near said at least one rolling stand (1) using several first application means (2), with this specified lubricant contains an emulsion of oil and water; characterized by the fact that Δv = v _s – v _r is the difference between the feed rate v _s of rolled products measured at the exit of at least one rolling stand (1) and the circumferential speed v _r of the work rolls (3) of said at least one rolling stand (1 ) measured during the rolling operation, and Δv ₀ = v _s0 - v _r0 is the calculated value of the specified difference, and each time when the ratio [(Δv * v _r0 )/ (v _r * Δv ₀ )] - 1 < L, where L is equal to a value from 0.0005 to 0.002, is not satisfied, before the specified at least one rolling stand, with Considering the feed direction of the article, only oil is applied to the aluminum article by means of the second application means (6) until the indicated ratio is fulfilled. 2. The method according to p. 1, in which L = 0.001. 3. The method according to claim 1 or 2, in which the feed speed v _s of the rolled product is measured preferably continuously using the first sensors (4) with the first data, and said circumferential speed v _r of the work rolls (3) is preferably measured continuously using the second sensors (5) to obtain second data; and wherein the control system preferably continuously receives said first data and second data, checks whether said ratio is met, and if said ratio is not met, actuates the second application means (6). 4. Method according to any of the preceding claims, wherein said oil and water emulsion is contained in a first reservoir (7) which supplies the first application means (2), and preferably in which said emulsion is mixed. 5. Installation for rolling products from aluminum or aluminum alloy, with the possibility of performing the rolling method according to any of the previous paragraphs, which contains: - at least one rolling stand (1); - several first application means (2) located near said at least one rolling stand (1) and configured to apply an emulsion of oil and water to the product; and which provides: - the first sensors (4) for determining the first data, and the first data are the values of the feed rate v _s of the rolled product coming out of at least one rolling stand; - second sensors (5) for determining second data, said second data being the circumferential speed v _r of the work rolls (3) of said at least one rolling stand (1); - several second application means (6) located near said at least one rolling stand and made with the possibility of applying only oil to the product; - control system (20) configured to: - receive said first data and said second data, - calculate the difference Δv = v _s – v _r , - check whether the ratio [(δv * v _r0 )/ (v _r * Δv ₀ )] – 1 < L, where Δv ₀ = v _s0 – v _r0 is the calculated value of the specified difference and L is the value in the range from 0, 0005 to 0.002, - and, if said ratio is not fulfilled, actuate said second application means (6). 6. Installation according to claim 5, which provides for: - a first reservoir (7) for holding said emulsion and supplying it to the first application means (2), preferably by means of a first dosing device (10); - preferably a second reservoir (8) for containing only oil and supplying it to the second application means (6), optionally by means of a second dosing device (9). 7. Installation according to claim 5 or 6, in which drying means (11) are provided, placed after at least one rolling stand (1), taking into account the direction of product supply and in front of the winder (12) and made with the possibility of removing water from the rolled product . 8. Installation according to any one of paragraphs. 5-7, in which, in the case of one or more reversible rolling stands (1), said first application means (2) and said second application means (6) are located on both sides of said rolling stand (1) along the product feed direction, preferably as above and below the product delivery plane. 9. Installation according to any one of paragraphs. 5-7, in which, in the case of at least two rolling stands (1) located one behind the other, said first application means (2) and said second application means (6) are located only on the supply side of each rolling stand, preferably as above and below the product delivery plane. 10. Installation according to any one of paragraphs. 5-9, in which said second application means (6) are located in a position close to the work rolls (3) of the rolling stand (1), but remote from the product supply plane, while said first application means (2) are located in a position remote from the work rolls (3) and close to the product feed plane. 11. Installation according to any one of paragraphs. 5-9, in which said second application means (6) are located in a position remote from the work rolls (3) of the rolling stand (1), but close to the product feed plane, while said first application means (2) are located in position near the work rolls (3), and remote from the product feed plane.

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