Classifications

• • 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
  • B21B13/00—Metal-rolling stands, i.e. an assembly composed of a stand frame, rolls, and accessories
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21B—ROLLING OF METAL
  • B21B31/00—Rolling stand structures; Mounting, adjusting, or interchanging rolls, roll mountings, or stand frames

Definitions

• the present invention relates to a new method of cooling rolls (or rolls) rolling, optionally variable diameter, based on a highly turbulent flow regime (high turbulence cooling, HTC).
• the process is called high turbulence work roll cooling (HTRC) work roll cooling.
• HTRC high turbulence work roll cooling
• the invention also relates to the device for implementing the method.
• the heating of the hot rolling rolls is due to the heat transfer to the rolls by conduction from the product, such as a metal strip, during rolling.
• the cooling of the rolling rolls has been studied intensively because of the very strong influence of it on the degradation of said rolls (wear) as a result of the thermomechanical fatigue generated and on the control of the cylinder crown. .
• the degradation of the cylinders has a very great influence on the product quality.
• Tubes or modules or cooling water tanks are equipped with sprayers and placed around each cylinder, with means for supplying cooling water.
• cooling water guide plates In association with the upper cylinder and the lower cylinder are arranged cooling water guide plates. These plates are provided with a scraper, for example covered with rubber, associated with each of the cylinders to prevent water from flowing over the product being rolled.
• the water can either be fed through one end of the head and evacuated through the other end (JP-A-20 84205), either be conveyed through both ends and be evacuated through the center (EP-A-919 297). , the evacuation being carried out through the head itself, scraper systems preventing leakage along the circumference of the rollers. Outward evacuation can still be performed between one end of the head and the surface of the roll (JP-A-1127713).
• JP-A-58 047502 there is further described a cooling shoe deformable by means of springs to be able to adapt to the surface of the roller.
• the present invention aims at providing a solution making it possible to overcome the drawbacks of the state of the art.
• this invention aims to provide efficient cooling of the rolling rolls while ensuring a reduction in thermomechanical fatigue and therefore less degradation of the roll surface.
• the invention also aims to request, equivalent heat exchange, a lower flow rate and water pressure than the cooling systems of the state of the art, particularly those with flat jet.
• a first object of the present invention relates to a cooling device for a working roll belonging to a roll stand of a long or flat product, characterized in that comprises a cooling head in the form of an essentially watertight box, except on a front face which is a short distance from said cylinder and in which a plurality of nozzles has been machined or positioned in a two-dimensional pattern, said box, provided with means for supplying cooling liquid, being concave and cylindrical at its front face with a radius such that, when the device is in the working position, the distance in the radial direction between said front face and the surface of the cylinder increases from the end of the box closest to the right-of-way and away from the product being rolled.
• the cooling head is equipped with a transverse bottom plate arranged longitudinally with respect to the cylinder and located at a distance from the cylinder such that said bottom plate cooperates with the front face of the box, so as to ensure the control of the coolant flow and the confinement of it in the form of a highly turbulent water cushion.
• This transverse bottom plate is mandatory in the case of small diameter cylinders.
• the cooling head is further provided with adjustable side plates arranged on the side of the transverse ends of the cylinder and located at a distance from the cylinder such that said side plates cooperate with the front face of the box and with the transverse bottom plate. , so as to ensure control of the coolant flow and confinement thereof in the form of a highly turbulent water cushion.
• the curvature of the side plates corresponds to the maximum curvature of the cylinders used on the installation.
• the front face comprises a plate or a sheet in which are positioned or machined sprinklers, the holes consist of small holes of axial right section.
• the orifices of the nozzles are of round, square or oval cross section.
• the radius of the cylindrical concave surface of the front face has a value greater than a maximum value of predetermined cylinder radius, which limits the usable cylinder size range.
• the machining pattern of the nozzles is chosen to make the cooling of the cylinder as homogeneous as possible over the entire surface of the cylinder and in particular over the width of the cylinder.
• the machining pattern of the nozzles is defined by the number, the position and the diameter or the size of the orifices in the plate of said front face.
• the orifices are machined according to a given network and the above drawing is obtained by closing certain orifices.
• the cooling liquid comprises water.
• Another object of the present invention relates to a cooling method of a working cylinder belonging to a roll cage of a product. or a flat product, in particular a metal strip, implementing the aforementioned device, characterized by the fact that:
• the cooling head is arranged near the surface of the cylinder to create a space between 5 and 200 mm between the front face of the box and said surface of the cylinder, said space increasing from the right-of-way and by moving away from the product being rolled; -
• the cooling head is supplied with cooling liquid, preferably water, and this water is injected into said space through nozzles having an orifice having a diameter of between 1 and 6 mm; -
• the coolant pressure is adjusted to a value between 1 and 6 bar and the specific flow between 100 and 500 m 3 / hour / m 2 , to create in the aforementioned space a liquid cushion in a highly turbulent regime.
• the coolant pressure in the box is less than 4 bar.
• the coolant pressure is between 2 and 4 bar. Still according to the method of the invention, the distance between the lower transverse plate and the cylinder is adjusted so as to obtain a specific liquid flow rate in the gap between 2 and 10 m / s, and preferably greater at 3 m / s.
• the side plates are set to have a minimum opening of between 0 and 10 mm.
• Figures IA and IB show schematically two embodiments showing the principle of a working cylinder cooling head on a hot rolling line according to the state of the art (flat nozzles).
• FIGS. 2A to 2D schematically show several embodiments showing the principle of such a cooling head in the case of the present invention (highly turbulent cooling).
• FIG. 3 represents graphically the evolution of the temperature over time, in different positions of the working cylinder respectively in a conventional installation at 8 bar of pressure and in the case of an HTRC installation according to the present invention, at 2.4 bar pressure and with water guide plates.
• FIG. 4 shows an industrial layout of an HTRC cooling head.
• FIG. 5 shows graphically the cooling performance of the installation according to the invention at low pressure (only at the level of the lower cylinder) in comparison with the high-pressure flat jet cooling, according to the state of the art.
• Figure 6 shows the degradation of the surface of the upper and lower cylinders respectively in the case of 3 HTRC configurations and a configuration according to the state of the art.
• FIG. 7 shows the surface state of a cylinder after a rolling campaign using cooling according to the state of the art (on the left) and HTRC cooling according to the present invention (on the right) respectively. . Description of an embodiment according to the state of the art
• Figures 1A and 1B show schematically a cooling installation of working rollers in a rolling mill, according to the state of the art, with, in this example either sprinklers mounted on independent tubes (Figure IA), or sprinklers arranged on a module ( Figure IB).
• the pair of rollers has an upper roll 1 and a lower roll 2 rotating in opposite directions to advance the steel strip 3.
• a cooling device 4A At the upper roll is a cooling device 4A, with its adjustment accessories, provided with nozzles Plates 40 facing the upper roller 1.
• a cooling device 4B At the bottom roller is a cooling device 4B, with its adjustment accessories, provided with flat nozzles 40 facing the lower roller 2.
• the jets are placed on 4 tubes while in the device of Figure IB, the jets are arranged in a module 4A, 4B.
• the distance between the nozzles and the cylinder is 150-500 mm, which does not allow to use cylinders of different diameters with a single cooling device.
• the cooling head is designed to implement the WPC technology, that is to say to create a highly turbulent water cushion between the cooling head and the surface of the working roller. Turbulence is caused by low water injection pressure in the water cushion through jet sprinklers developed by the Applicant.
• the cooling installation according to the invention consists of an upper box ⁇ h facing the upper roll 1 and a lower box 6B facing the lower roll 2.
• Each box 6A , 6B comprises a concave surface 42 opposite the corresponding roller 1, 2.
• This concave surface 42 consists of a wall provided with a plurality of orifice of specific size forming straight jets 41 and forming a drawing determined.
• the concave surface 42 may advantageously cover a greater portion of circumference in the case of the upper cylinder 1, than in the case of the lower cylinder 2.
• the water cushion is formed in the space limited by the roller and the cooling head, but also, if necessary, by a transverse lower guide 7 (Figure 2B) and / or by transverse guides 5, 7 and lateral 8 ( Figures 2C and 2D).
• the lateral guides 8 can be mounted adjustably depending on the roll diameter.
• the properties of the water cushion are also a function of the water flow. The heated water flows outward by gravity or pressure at the interstices between the cylinders and the guides, without additional evacuation device.
• the shape of the cooling head and the distribution pattern of the jet jets are specific to the present development, particularly with regard to taking into account variations in diameter, automatic changes of work rolls, for checking roller profiles, maintenance requirements as well as offset and curvature of the work rolls.
• the shape of the cooling head has been machined to have intensive cooling close to the right of way. The distance between the surface of the head and the surface of the working roller thus decreases toward the end of the head closest to the right-of-way 9, where this distance is the smallest.
• the radius of the concave part of the cooling head must be greater than the maximum possible radius of the working roller.
• transverse plates 5, 7 and adaptable side 8 were provided to control the flow of water but also to ensure the formation and stabilization of the water cushion ( Figures 2C and 2D).
• the distribution pattern of the jet sprinklers was selected to obtain an optimal homogeneity of the turbulence in the water cushion and also to control the thermal evolution and the cylinder crown, taking into account the distribution of water. Differential water over the entire width of the working roller.
• FIG. 3 shows a comparison of the temperature decrease over time of the Cryotron probe, used to determine the transfer coefficient, between a conventional installation 21 (in gray) cooling with flat nozzles operating under a pressure of 20 ° C.
• FIG. 5 shows the temperature difference between the lower and upper rollers as a function of the width measurement position on the roll, counted from the engine side (squares: HTRC on lower roll; triangles: state of the roll). technical). The performances are very similar. If HTRC cooling is performed on both the upper and lower rolls, the roll temperature is at least 70 ° C lower than the performance achieved with the prior art systems (no represent) .
• a lower water flow pressure and preferably between 2 and 4 bar is sufficient. This allows substantial savings over a period of a year for example.
• Figure 6 shows the effect of cooling on the degradation of the surface of the work rolls (Figure 4 installation).
• the four upper views correspond to a flat nozzle cooling of the upper roller according to the state of the art.
• Bottom views # 1, 2 and 4 are cooling inner roller according to the present invention; the view No. 3 corresponds to a cooling of the lower roller according to the state of the art.
• Figure 7 shows in detail the surface condition of the top roll (conventional cooling, on the left) and the lower roll (cooling HTRC, on the right), respectively, after a typical rolling campaign.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Control Of Metal Rolling (AREA)
• Metal Rolling (AREA)
• Reduction Rolling/Reduction Stand/Operation Of Reduction Machine (AREA)
• Heat Treatment Of Articles (AREA)
• Laminated Bodies (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (3)

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Cited By (2)

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• 2007
  • 2007-02-09 BE BE2007/0055A patent/BE1017462A3/fr not_active IP Right Cessation
  • 2007-12-20 AT AT07855376T patent/ATE524249T1/de active
  • 2007-12-20 ES ES07855376T patent/ES2372631T3/es active Active
  • 2007-12-20 PL PL07855376T patent/PL2114584T3/pl unknown
  • 2007-12-21 KR KR1020097016566A patent/KR101452835B1/ko active Active
  • 2007-12-21 JP JP2009548550A patent/JP5351050B2/ja active Active
  • 2007-12-21 WO PCT/BE2007/000129 patent/WO2008104037A1/fr not_active Ceased
  • 2007-12-21 CN CN2007800510816A patent/CN101600519B/zh active Active
  • 2007-12-21 BR BRPI0720818A patent/BRPI0720818B1/pt active IP Right Grant
  • 2007-12-21 EP EP07855376.5A patent/EP2114584B8/de active Active
  • 2007-12-21 US US12/525,743 patent/US8281632B2/en active Active

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