Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21B—ROLLING OF METAL
  • B21B37/00—Control devices or methods specially adapted for metal-rolling mills or the work produced thereby
  • B21B37/28—Control of flatness or profile during rolling of strip, sheets or plates
  • B21B37/30—Control of flatness or profile during rolling of strip, sheets or plates using roll camber control
  • B21B37/32—Control of flatness or profile during rolling of strip, sheets or plates using roll camber control by cooling, heating or lubricating the rolls
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21B—ROLLING OF METAL
  • B21B27/00—Rolls, roll alloys or roll fabrication; Lubricating, cooling or heating rolls while in use
  • B21B27/06—Lubricating, cooling or heating rolls
  • B21B27/10—Lubricating, cooling or heating rolls externally
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21B—ROLLING OF METAL
  • B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
  • B21B1/22—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling plates, strips, bands or sheets of indefinite length
  • B21B2001/221—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling plates, strips, bands or sheets of indefinite length by cold-rolling
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21B—ROLLING OF METAL
  • B21B27/00—Rolls, roll alloys or roll fabrication; Lubricating, cooling or heating rolls while in use
  • B21B27/06—Lubricating, cooling or heating rolls
  • B21B27/10—Lubricating, cooling or heating rolls externally
  • B21B2027/103—Lubricating, cooling or heating rolls externally cooling externally
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21B—ROLLING OF METAL
  • B21B45/00—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
  • B21B45/02—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills for lubricating, cooling, or cleaning
  • B21B45/0203—Cooling
  • B21B45/0209—Cooling devices, e.g. using gaseous coolants
  • B21B2045/0212—Cooling devices, e.g. using gaseous coolants using gaseous coolants
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21B—ROLLING OF METAL
  • B21B38/00—Methods or devices for measuring, detecting or monitoring specially adapted for metal-rolling mills, e.g. position detection, inspection of the product
  • B21B38/006—Methods or devices for measuring, detecting or monitoring specially adapted for metal-rolling mills, e.g. position detection, inspection of the product for measuring temperature
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21B—ROLLING OF METAL
  • B21B9/00—Measures for carrying out rolling operations under special conditions, e.g. in vacuum or inert atmosphere to prevent oxidation of work; Special measures for removing fumes from rolling mills

Definitions

• the present invention relates to a method for the cold rolling of metallic rolled stock, which for plastic deformation enters a roll gap formed between oppositely rotating rolls on a run-in side and leaves the roll gap on a run-out side, deformation heat that is produced being removed by supplying an industrial gas which is at a lower temperature than the rolled stock.
• a strand - for example in the form of a strip, profile or sheet of steel, nonferrous metals, aluminium or other metals - is continuously fed to a rolling stand and cold-formed in it.
• the rolled stock is not heated before the plastic deformation.
• the change in shape below the respective recrystallization temperature of the metals brings with it advantageous changes in properties, for example an increase in strength and hardness.
• the deformation energy that is introduced into the rolled stock causes internal friction, and consequently heat, which on the one hand changes the material properties of the rolled stock and on the other hand leads to gradual heating up of the rolling stand, and consequently to changes in the properties of the product, such as the surface and flatness of the rolled strip and oxidation.
• inert gas for "gas cooling lubrication” offers particularly good protection from oxidation by completely displacing the ambient air and avoids remains of lubricant on the surface of the rolled stock.
• the proposed cooling of the surface of the rolled stock may cause moisture to condense and cause corrosion when it leaves the inert environment, and on the other hand the oxygen content of the ambient air is reduced by the sup- ply of large amounts of inert gas, which can lead to health problems for the personnel working in the vicinity of the rolling stand.
• the present invention is based on the object of providing a cold rolling method which avoids the aforementioned problems.
• the development according to the invention of the known method for "gas cooling lubrication” essentially consists in that the industrial gas is supplied in a controlled manner on the basis of the surface temperature of at least one roll.
• the roll temperature is kept constant, that is to say counteracting both gradual heating up of the rolls and gradual cooling down.
• the surface temperature is determined at one of the rolls - or at a number of rolls with subsequent averaging.
• the known temperature measuring methods in particular optical measuring methods, are suitable for the determination.
• Industrial gases that are suitable for "gas cooling lubrication" are inert gases such as nitrogen, argon, carbon dioxide and mixtures thereof - but also air, as explained in more detail further below.
• the surface temperature of the roll increases as it rotates about its axis of rotation from the run-in side to the run-out side.
• the roll is heated by the frictional heat pro- **d at the bearings.
• the surface temperature of the roll is therefore at its highest and may have irregular temperature peaks, which in the region of the run-in side are levelled out and not falsified by previously applied industrial gas. Therefore, the surface temperature of the roll in the region of the run-in side is particularly suitable as a measure for determining the necessary amount of industrial gas.
• the industrial gas is not supplied to the surface of the rolled stock or directly to the roll gap, but is applied directly to the surface of the roll.
• the method according to the invention particular attention is given to the setting of the surface temperature of the rolls to a predetermined temperature or within a predetermined temperature range. The direct cooling of the roll ensures that the deformation heat in the roll gap and frictional heat at the bearings of the rolls is completely or largely removed.
• the surface temperature of the roll is at its highest in the region of the run-out side.
• the industrial gas is therefore used most effectively on the run-out side of the roll, since the temperature difference between the surface of the rolls and the industrial gas that is necessary for heat transfer is at its greatest and, as a result, the required amount of industrial gas can be minimized.
• the high-impact application of the industrial gas to the surface of the rolls further improves the effectiveness of the use of the industrial gas, so that, in a preferred variant of the method, the industrial gas is sprayed onto the outer cylindrical surface of the roll.
• High-impact spraying of the industrial gas allows the amount of gas required to be further reduced.
• a further improvement with regard to the efficiency of the use of gas is achieved if the industrial gas is directed onto the roll in a stream of coolant, the main direction of flow of which is essentially perpendicular to the outer cylindrical surface of the roll.
• This measure also makes it easier in particular to set a high impact pulse when spraying the inert gas onto the surface of the rolls.
• the industrial gas is supplied in a cryogenic gaseous form, but with preference in a liquid form.
• a gas containing carbon dioxide is used as the industrial gas.
• Carbon dioxide is inexpensive and can be easily handled.
• the carbon dioxide is kept liquid at ambient temperature in a supply line and is directed onto the outer cylindrical surface on the run-out side of at least one of the rolls as a cryogenic carbon dioxide gas or in the form of a mixture of dry ice and carbon dioxide gas.
• the carbon dioxide is kept available in a liquid state in the supply line without complex cooling measures.
• This storage of the liquid carbon dioxide in the supply line that. is preferred according to the invention requires only moderate pressures even at ambient temperature.
• the liquid carbon dioxide expands at ambient pressure, a transformation of the liquid carbon dioxide into solid and gaseous carbon dioxide takes place.
• the heat of evaporation and sublimation that is necessary for this brings about a cooling down of the carbon dioxide and leads to particularly effective heat removal from the surface of the rolls.
• the carbon dioxide is directed onto the outer cylindrical surface on the run-out side of at least one of the rolls avoids impairments of the surface of the rolled stock that may occur if dry ice, which forms when liquid carbon dioxide expands at ambient pressure, is drawn into the gap. Small amounts of unused ice sublimate without leaving any residue on the rolled stock on the run-out side of the rolls.
• the liquid carbon dioxide supplied via the supply line of the roll is preferably sprayed with high impact onto the surface of the roll that is to be cooled in a gaseous and solid (ice) form via at least one nozzle.
• an industrial gas which contains liquefied or gaseous cryogenic air is used.
• the industrial gas is supplied to the surface to be cooled in a gaseous form, but with preference in liquid form.
• the use of air for cooling is unproblematical with regard to contamination of the air in the working area, so that even relatively high use of industrial gas can be safely maintained when a particularly low surface temperature of the roll is desired or particularly great amounts of heat are to be removed. It has been found that the proportion of oxygen in the air is not critical with respect to oxidation of the rolls and of the rolled stock when setting a low temperature level.
• the control of the supply of industrial gas on the basis of the average surface temperature of the rolls takes place manually or automatically. It is preferred, however, for the surface temperature of the rolls to be kept at a setpoint value by means of an automatic control, the throughflow of the industrial gas or a parameter which can be correlated with it being used as the manipulated variable of the control.
• the industrial gas demand required for maintaining the surface temperature is set by means of the automatic control by changes of the mass throughflow or volume throughflow of the industrial gas.
• the accuracy that can be achieved on the basis of the automatic temperature control allows the use of industrial gas to be minimized further. It has proven successful if the setpoint value of the surface temperature of the rolls lies in the range between +/- 20% of the maximum temperature of the rolled stock on the run-in side.
• the surface temerature of the roll niay be controlled to a constant setpoint temperature value within a tolerance range, which lies between +/- 20% of the maximum temperature of the rolled stock on the run-in side, or it is just ensured that the surface temperature keeps within this tolerance range.
• the industrial gas is preferably directed onto the roll along a cooling section, which extends parallel to the longitudinal axis of the rolls.
• the cooling section extends over the entire length of the roll or a large part of the entire length and so allows particularly uniform cooling of the surface of the roll and the rolled stock, so that stresses and changes in shape caused by local differences in temperature are reduced.
• a spraying device is preferably used, arranged along the longitudinal axis of the rolls and on the run-out side of the rolled stock.
• Figure 1 shows in a schematic representation a side view of a rolling stand with coolant nozzles arranged on the run-out side of the rolls for the automatically controlled supply of coolant according to the method as provided by the invention.
• Figure 1 schematically shows a cold rolling stand with two rolls 1, 2 arranged one vertically above the other, which form a roll gap 3, through which rolled stock in the form of a metal strip 4 is drawn in the direction of the arrow 9.
• nozzles 5 for the supply of a coolant in liquid form to the surface of the rolls.
• the nozzles 5 are formed as tubular nozzles which extend along the entire length of both rolls 1, 2.
• the liquid jet 6 emerging from the nozzles 5 is directed at the surface of the rolls I 5 2, its main direction of propagation, which is identified by the dashed line 5a, extending perpendicularly in relation to the outer cylindrical surface 20 of the respective roll 1, 2.
• the surface temperature of the rolls 1 and 2 is recorded at a measuring point 11 on the strip entry side "A" by means of the pyrometers 7 and 8.
• the pyrometers 7 and 8 are each connected to a temperature controller 9 and 10, by means of which the measured value of the surface temperature is recorded and evaluated for controlling the supply of coolant.
• pneumatically activated throughflow control valves 14 and 15, which are respectively connected to one of the temperature controllers 9, 10, are fitted in the supply lines for the coolant 12, 13.
• the rolls 1, 2 are driven in a rotating manner, whereby the rolled stock 4 is drawn through the roll gap 3 while undergoing plastic deformation.
• the surface temperature of the rolls 1 and 2 is recorded by means of the pyrometers 7, 8 and the measured value is passed on to the temperature controllers 9, 10.
• the surface temperature of the rolls 1, 2 is controlled by means of the temperature controllers 9, 10 to a predetermined setpoint value, which may lie in the temperature range between minus 20°C and plus 6O 0 C. In the exemplary embodiment, the setpoint value is set to 20°C.
• the manipulated variable for this is the mass flow or volume flow of the coolant sprayed onto the rolls 1, 2, which is supplied to the nozzles 5 via the control valves 14, 15.
• Liquid carbon dioxide is used as the coolant, fed into the supply lines 12, 13 from a liquefied gas tank 18 via a feed line 16 which can be closed by means of a ball- cock 17, the carbon dioxide being located in the supply lines 12, 13 in a liquid state of aggregation in the range from 252 to 304 K at a pressure of 19 to 73 bar.
• the carbon dioxide is supplied in a liquid form at about 292 K and 56 bar. When it leaves the nozzles 5, gaseous carbon dioxide and dry ice form, impinging with high impact on the surface of the rolls. Evaporation and sublimation of the carbon dioxide has the result that the cooling of the rolls 1, 2 takes place very effectively.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Metal Rolling (AREA)

Applications Claiming Priority (2)

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• 2005
  • 2005-01-13 DE DE200510001806 patent/DE102005001806A1/de not_active Ceased
• 2006
  • 2006-01-06 WO PCT/EP2006/000070 patent/WO2006074875A1/en not_active Ceased
  • 2006-01-06 BR BRPI0606654-2A patent/BRPI0606654A2/pt not_active IP Right Cessation
  • 2006-01-06 EP EP06700773A patent/EP1838470A1/de not_active Withdrawn
  • 2006-01-06 CN CNA2006800021957A patent/CN101102856A/zh active Pending

Non-Patent Citations (1)

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