JP2011189404A - Temper rolling mill having excellent roughness transfer efficiency, and temper rolling method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a temper rolling mill using a dull work roller and efficiently producible of a metal strip having the desired surface roughness, in particular, a flexible metal strip and a hard metal strip having the desired surface roughness. <P>SOLUTION: The temper rolling mill has dull work rollers 1, 2 having the surface roughness of ≥1 μm Ra, the roller diameter of ≥1,000 mm and ≤1,400 mm, and rolls a metal strip S having the 0.2% proof stress of ≤350 MPa at the percentage of elongation of ≥0.2% and ≤3.0%. The temper rolling mill has dull work rollers 1, 2 having the surface roughness of ≥1 μm Ra, the roller diameter of ≥1,000 mm and ≤1,400 mm with the Young's modulus of a roller surface layer being ≥450 GPa, and rolls a metal strip S having the 0.2% proof stress of >350 MPa at the percentage of elongation of ≥0.2% and ≤3.0%. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a temper rolling mill and a temper rolling method that are excellent in roughness transfer efficiency of a metal strip.

  Generally, a metal strip with a dull work roll finish shipped as a product has a plate thickness, flatness, strength, elongation, and surface roughness (any of Ra and others expressed by arithmetic mean roughness described in JIS B 0601). However, it is required that the arithmetic average roughness Ra) is within a desired range. Regarding plate thickness, automatic plate thickness control (AGC, automatic elongation rate control is the same meaning), flatness is AFC (automatic shape control) and tension leveler correction, strength and elongation are handled by elongation rate or reduction rate. is doing.

  Regarding the surface roughness, the surface roughness of the work roll that is incorporated in the temper rolling mill from the metal strip material and elongation experience, and the metal strip rolled by a cold tandem rolling mill and heat-treated by a continuous annealing furnace. Temper rolling with standardization, and work roll usage conditions (total number of coils, total rolling weight, or total rolling length) so that the surface roughness of the metal strip after temper rolling falls within the target range When the rolling is performed and the above use conditions are not satisfied, the work rolls are rearranged to be dealt with.

  Measure the surface roughness of the metal strip after temper rolling, adjust the elongation of the next coil based on the result, and consider the decrease in surface roughness corresponding to work roll wear. It is an effective means to control the surface roughness of the metal strip by adjusting the rolling load (elongation rate) of the next coil according to the cumulative rolling amount so that the surface roughness of the strip becomes constant (for example, patent document) 1 and 2). In particular, adjusting the elongation rate is effective in the case where the 0.2% yield strength is a relatively hard material having a strength of over 350 MPa and the elongation rate is loosely limited.

  However, since a relatively soft material having a 0.2% proof stress of 350 MPa or less has poor roughness transfer efficiency, the surface roughness of the metal strip after temper rolling does not change much even if the elongation rate is slightly increased. There is. If the elongation rate is greatly increased, the surface roughness of the metal strip after temper rolling can be changed, but the required mechanical properties (strength and elongation) of the material cannot be satisfied. For this reason, a soft material could not give a large surface roughness to the metal strip after temper rolling (substantially change the surface roughness). For the above reason, in the case of a soft material, it is necessary to make a material having a large surface roughness with the cold tandem rolling mill described above. In other words, since it was difficult to build a surface roughness in temper rolling with a soft material, it was necessary to build it with a cold tandem rolling mill.

When creating surface roughness with a cold tandem rolling mill, there are not many degrees of freedom in the rolling schedule, so we have many work rolls with different surface roughness according to the fine range, and the surface roughness of the desired product. Depending on the degree, the work rolls need to be reassigned frequently. When the work rolls are rearranged, the rolling mill stops during that time, so that there is a problem that productivity is lowered. On the other hand, since the surface roughness affects the stability of sheet passing in the continuous annealing process, the variation in heat treatment, the press formability during secondary processing, and the sharpness after painting, the surface roughness of the metal strip is strict. There is a high demand for downsizing (narrow range). In order to meet this need, the roll replacement ratio is further increased, or the surface roughness of the rolled metal strip is measured for each coil and stored as an inventory. It is dealt with by selecting and shipping from among them. However, when the work roll exchange ratio is increased, productivity is reduced and the manufacturing cost is increased, and holding a large amount of inventory newly increases the manufacturing cost.
Furthermore, temper rolling has a flexible reduction schedule, so the controllable range of surface roughness is wide, and even with the same roll change, the frequency of roll change in temper rolling is lower than that of tandem rolling, and the manufacturing cost is reduced. There is an advantage that it is cheap.
For this reason, the technique which can build in the surface roughness of a soft material by temper rolling has been desired.

Japanese Patent Laid-Open No. 2002-1410 Japanese Patent Laid-Open No. 2-155501

  The present invention provides a dull work roll capable of efficiently producing a metal strip having a surface roughness desired by the metal strip, particularly a soft material, and further having a surface roughness desired by the soft and hard metal strips. It is an object to provide a temper rolling mill and a temper rolling method used.

  In order to solve the above problems, the temper rolling mill of the first invention includes a dull work roll having a surface roughness expressed by arithmetic mean roughness of 1 μmRa to 10 μmRa and a roll diameter of 1000 mm to 1400 mm. In addition, when rolling a metal strip having a 0.2% proof stress of 350 MPa or less obtained from a tensile test, it has a function of rolling at an elongation of 0.2% or more and 3.0% or less.

The temper rolling mill of the second invention is a temper rolling mill, comprising a dull work roll having a surface roughness represented by arithmetic mean roughness of 1 μm Ra or more and 10 μm Ra or less, a roll diameter of 1000 mm or more and 1400 mm or less,
When rolling a metal strip having a 0.2% proof stress of 350 MPa or less obtained from a tensile test, the Young's modulus of the roll surface layer is rolled on a dull work roll, and when rolling a metal strip having a 0.2% proof stress exceeding 350 MPa obtained from a tensile test. Can be replaced with 450GPa or more dull work rolls,
It has a function of rolling at an elongation of 0.2% to 3.0%.

  The temper rolling mill of the third invention is the temper rolling mill of the third invention, wherein the temper rolling mill of the first invention or the second invention is a two-stage rolling mill, wherein the upper and lower work rolls intersect ( Hereinafter, it is characterized by providing a “roll cross mechanism”.

  In the temper rolling mill of the fourth invention, the temper rolling mill of the first or second invention is a two-stage rolling mill, wherein work rolls with asymmetric crowns in the sheet width direction are arranged symmetrically in the vertical direction. A mechanism for moving the upper and lower work rolls in the plate width direction (hereinafter referred to as “roll shift mechanism”) is provided.

  The temper rolling method according to the fifth aspect of the present invention is 0.2 obtained from a tensile test using a dull work roll having a surface roughness expressed by arithmetic mean roughness of 1 μmRa or more and 10 μmRa or less and a roll diameter of 1000 mm or more and 1400 mm or less. A metal strip having a% proof stress of 350 MPa or less is rolled at an elongation of 0.2% to 3.0%.

The temper rolling method of the sixth invention uses a dull work roll having a surface roughness expressed by arithmetic mean roughness of 1 μmRa to 10 μmRa, a roll diameter of 1000 mm to 1400 mm,
When rolling a metal strip having a 0.2% proof stress of 350 MPa or less obtained from a tensile test, a dull work roll is used.
When rolling a metal strip having a 0.2% proof stress exceeding 350 MPa obtained from a tensile test, a dull work roll having a Young's modulus of the roll surface layer of 450 GPa or more is used.
It is characterized by rolling at an elongation of 0.2% or more and 3.0% or less.

  In the temper rolling mill of the first invention and the temper rolling method of the fifth invention, it is possible to efficiently produce a metal strip having a desired surface roughness (Ra) in a narrow range for a soft material, and productivity. Can be improved and the manufacturing cost can be reduced. In addition, roll exchange in tandem rolling to obtain roughness can be avoided, and the frequency of exchange is less than that in roll exchange in tandem rolling to obtain roughness, thereby reducing manufacturing costs. be able to.

  In the temper rolling mill of the second invention and the temper rolling method of the sixth invention, in addition to the effects of the temper rolling mill of the first invention and the temper rolling method of the sixth invention, by replacing the dull work roll There is an effect that a metal strip having a desired surface roughness can be produced for a soft material and a hard material with one temper rolling mill.

It is a diagram which shows the relationship between elongation rate and the roughness transfer efficiency after temper rolling about a soft material and a hard material, and shows the influence of the material which has on the roughness transfer efficiency. It is a diagram which shows the relationship between elongation rate and the rolling load (unit load) per unit width about a soft material and a hard material, and shows the influence of the material which acts on a rolling load. It is a diagram which shows the influence of the dull work roll diameter and the dull work roll material which exerts on the rolling load (line load) per unit width. 1 shows an embodiment of the present invention and is a configuration diagram of a temper rolling mill.

  In general, the rolling factors affecting the surface roughness of a metal strip after cold rolling are known to include rolling load (linear load), tension, lubrication, elongation, steel type, work roll diameter, and work roll surface roughness. The higher the load level, the closer the surface roughness of the metal strip after rolling approaches the surface roughness of the work roll. Therefore, when the material is different even under the same rolling conditions, the surface roughness of the metal strip after rolling is different.

FIG. 1 is a diagram showing the influence of materials on the roughness transfer efficiency (η (%)) after temper rolling, and FIG. 2 is a diagram showing the rolling load per unit width at that time. Here, the transfer rate (η (%)) is the surface roughness S ₀ (μmRa) of the metal strip before cold rolling, the surface roughness S _WR (μmRa) of the work roll, and the metal after cold rolling. It is defined by the formula (1) using the surface roughness S (μmRa) of the strip.
η = 100 (S ₀ −S) / (S ₀ −S _WR ) (1)

  In FIG. 1, a soft material is a steel material (hereinafter referred to as “BH”) having a 0.2% proof stress obtained from a tensile test (hereinafter referred to as “BH”), and a hard material is a high-tensile material having a 0.2% proof stress obtained from a tensile test of 600 MPa. (Hereinafter referred to as “100K”). All the materials are the results of wet temper rolling with a dull roll (roll surface roughness 3.2 μmRa) having a plate thickness of 1 mm, a material surface roughness of 0.8 μmRa and a work roll diameter of 500 mm.

  FIG. 1 clearly shows that the transfer efficiency of the soft material is significantly inferior to the transfer efficiency of the hard material. For example, at an elongation of 0.5%, the transfer rate of the hard material is 12%, whereas the transfer rate of the soft material is 2%. In order to secure a transfer rate of 10% or more with a soft material, it is necessary to obtain an elongation rate of 1.1% or more. In general, if the elongation rate is increased, the mechanical material of the product will not be satisfied, or it will deviate from the target plate thickness, so there is a limit to the elongation rate that can be adopted by temper rolling. The purpose of temper rolling is to remove the shape correction and stretcher strain material in addition to the above roughness adjustment, and the lower limit of the elongation rate is 0.2%. This is because the shape correction becomes insufficient, and the upper limit of the elongation rate of 3% is the upper limit value of the soft material necessary for completely preventing the stretcher strain. In addition, it is obvious that the upper limit value of the soft material necessary for completely preventing the above-described tretler strain is different for each steel type, and here, the maximum value among the soft material steel types is shown.

  As can be seen from FIG. 2, the rolling load of the soft material is significantly lower than the rolling load of the hard material. At an elongation of 0.5%, the rolling load of the hard material is 7.2 MN / m, while the rolling load of the soft material is 0.2 MN / m.

  The inventors focused on the rolling load for the transfer efficiency of soft and hard materials, conducted an experiment using a rolling mill, and investigated the influence of the work roll diameter as a rolling factor on the surface roughness of the metal strip after rolling. did. As other rolling factors affecting the rolling load, tension, lubrication, and the like can be considered, but even if these are changed, the rolling load is excluded because it is limited to several times.

  Hereinafter, experimental results will be described. FIG. 4 shows a rolling mill used in this experiment or a rolling mill used as an actual machine. The rolling mill used in this experiment has a work roll barrel length of 300 mm, which is shorter than that of the rolling mill used as an actual machine, but is a side view and omits the housing. Therefore, it is the same in terms of expression in the drawing as a two-high rolling mill used as an actual machine described later. Since the rolling mill used in this experiment is experimental, the diameter of the work roll can be changed step by step by changing from 400 mm to 1600 mm. In addition, the work roll diameter of a normal actual machine is about 400 to 500 mm in a 6-high rolling mill, and is about 600 to 700 mm in a 4-high rolling mill.

  The work roll is a composite roll in which a normal forged steel roll (Young's modulus: 206 GPa) and a carbide sleeve (Young's modulus: 560 GPa) are cooled and fitted to the roll body. The Young's modulus of the surface layer can be adjusted by the WC component. The thickness of the surface layer is 100 mm. FIG. 3 shows the influence of the work roll diameter and Young's modulus on the temper rolling load of 0.5% elongation rate of soft and hard materials. However, the work roll surface roughness was 3.5 μmRa, and rolling was performed while lubricating oil was applied on the rolling mill entrance side. The used coils are BH (soft material) and 100K (hard material), and are unannealed coils with a plate thickness of 1 mm and a plate width of 100 mm. Rolling was performed under the same rolling conditions at an elongation of 0.5%, the rolling mill was stopped for each coil, and the surface roughness of the work roll and the surface roughness of the metal strip after rolling were measured.

  FIG. 3 shows that the rolling load (line load) per unit width increases as the work roll diameter increases. This is due to the effect of increasing the geometric contact length as the roll diameter increases and the effect of changes in roll flatness (generation of rigid body regions). In order to ensure the same level of line load as that of a hard material having an elongation rate of 0.5% with a soft material, it has become clear that the work roll diameter needs to be about 1200 mm.

  In actual operation, temper rolling of 100K-class high-tensile steel is carried out mainly in a range of 0.5% ± 0.2% on a 6-high rolling mill. The range was ± 0.2%. On the other hand, although not shown, it has been confirmed that the transfer efficiency of the surface roughness is almost the same transfer efficiency when the line load is set to the same level.

  As shown in FIG. 3, when the line load range of operation is set, when the BH material, which is a soft material, is rolled with a forged steel roll, when the work roll diameter is 800 mm, the line load deviates from the lower operating condition and is 1600 mm. Fell off the higher. From this, it can be seen that the work roll diameter that can cover the linear load range of the operation is 1000 mm or more and 1400 mm or less. In addition, since the surface roughness of the soft material can be secured by increasing the linear load using a large-diameter roll in the temper rolling as described above, the roll change in the tandem rolling to obtain the roll roughness is avoided. Cost increase can be avoided.

  In addition, if a 100K class high tension is rolled with the above-mentioned large diameter work roll, a rolling load will increase too much. Although it is possible to change the roll diameter of 400 to 1600 mm in the experimental rolling mill, in the actual machine, when such a roll diameter is greatly changed, it is necessary to change the structure of the rolling mill. Specifically, the equipment cost increases, such as higher rigidity of the housing post (increase in cross-sectional area), larger size of the hydraulic reduction device, and larger size of the bearing (including chock). In order to prevent these, when the hard material is temper-rolled, the surface layer of the work roll is made of carbide. Since the linear load of 100K class high tensile steel can be maintained at the current level by making it super hard, the above problem can be solved. Roll flatness was predicted using the Hitchcock equation by elasto-plastic FEM calculation taking into account the rigid body region in the roll, and experiments based on this revealed that the Young's modulus of carbide is preferably 450 GPa or more. The upper limit of the Young's modulus of cemented carbide is not particularly specified, but is assumed to be about 640 GPa from the elastic modulus of the WC component. By changing the Young's modulus in this way, it is possible to avoid changing the roll diameter when changing the roll when rolling the hard material, making it easy to change the roll, and changing the structure of the rolling mill.

  Although the transfer efficiency can be ensured by the combination of the work roll diameter and the roll material (surface roughness can be built by temper rolling), shape control remains an issue. In a normal rolling mill, a work roll bender that controls the bending deformation of the work roll is used. However, in a two-stage rolling mill like the present invention, the position of the load fulcrum and the bender action fulcrum are almost the same, It hardly works. Although the decrease bender works, this alone lacks shape control ability. Therefore, it is basically necessary to have a number of work rolls with appropriate roll crowns for each steel type, sheet thickness, and sheet width, and recombine according to the temper rolling conditions. Causes to increase.

  Therefore, in the present invention, an upper and lower roll cloth mechanism or a roll shift mechanism is provided as the shape control means. Although these techniques are publicly known (for example, Japanese Patent Laid-Open No. 10-99903 for crossing and Japanese Patent Laid-Open No. 8-117809 for shift), a large-diameter work roll two-stage rolling mill as in the present invention exhibits a special effect. .

  FIG. 4 is a block diagram showing an example of a rolling mill for carrying out the present invention. Although not shown, a continuous annealing facility is arranged upstream of the temper rolling mill 9, and the heat-treated metal strip S is continuously supplied. Although not shown in the figure, downstream of the temper rolling mill 9, a cutting machine for cutting the temper rolled metal strip S and a take-up reel for winding the temper rolled metal strip in a coil shape. Is arranged.

  The temper rolling mill 9 is composed of a single rolling stand, is a two-stage rolling mill, and is composed of large-diameter work rolls 1 and 2. A spindle (not shown) is connected to the work rolls 1 and 2 and is driven by an electric motor (not shown). The work rolls 1 and 2 can be rearranged depending on whether the rolled material is a soft material or a hard material. The work roll in the case of a soft material is made of steel having a Young's modulus of around 206 GPa. The work roll in the case of a hard material consists of WC whose surface layer has a Young's modulus of 450 GPa or more. Although not shown, a PLG is attached to the electric motor, the rotational speed is detected, and the peripheral speed of the work roll is detected in consideration of the gear ratio and the work roll diameter. A known roll changing device (not shown) is disposed adjacent to the temper rolling mill 9. Depending on whether the rolled material is a soft material or a hard material, the dull work roll is rearranged by a roll changing device.

  Roll cross mechanisms or roll shift mechanisms 6 and 7 are arranged as shape control means, and the upper and lower work rolls are controlled so that a desired roll crossing angle or roll shift amount is obtained. A rolling load detection device 3 is arranged above the upper work roll chock (not shown), and loads on the work side and the drive side are detected. In addition, an electric reduction device 4 is disposed above the rolling load detection device 3, and a pass line adjustment when the metal strip S is rolled is performed. Furthermore, a hydraulic reduction device 5 for applying a rolling force is disposed below the lower work roll chock (not shown).

  A touch roll 10 is provided on the entry side of the temper rolling mill 9, and a touch roll 11 is provided on the exit side of the temper rolling mill 9. Although not shown, PLG is attached to these entry / exit side touch rolls, and the elongation rate is measured by detecting the plate speed of the metal strip S before and after the temper rolling mill. Moreover, the load cell is attached to these touch rolls, and the tension | tensile_strength of the metal strip S before and behind a temper rolling mill is detected. The tension is controlled to be a desired tension by the bridle rolls 12 and 13 installed before and after the rolling mill 9. Also, deflector rolls 14 and 15 are installed upstream and downstream of the bridle roll. Further, a lubricant during temper rolling is supplied from the lubricating oil supply nozzle 8 on the entrance side of the rolling mill.

Example 1
Using the temper rolling mill shown in FIG. 4 as an example of the present invention, the target surface roughness is 1.0 to 1.2 μmRa, and the roughness after temper rolling at an elongation of 0.5% is We investigated and confirmed the effect of the present invention. This surface roughness of 1.0 to 1.2 μmRa is one of the roughness ranges suitable for obtaining, for example, good paintability or good gloss after coating or press moldability of structural parts for automobiles. It is.
The rolling mill has a work roll diameter of 1200 mm, body length of 1800 mm, material is forged steel, and roll roughness is 3.2 μmRa (discharge dull processing). did. The coil used is soft material BH, and its 0.2% proof stress is 250 MPa. The annealed unheated coil S has a plate thickness of 1 mm, a plate width of 1020 mm, and a surface roughness of 0.8 μmRa. The metal strip S is heat-treated in a continuous annealing furnace, the coils are joined by a welding machine installed on the entry side of the continuous annealing furnace, and the metal strip is continuously supplied. The crossing angle of the upper and lower work rolls was adjusted so that the plate shape was flat.

  Also, as a conventional technology, a normal 6-high rolling mill (work roll diameter 480 mm, body length 1800 mm, material is forged steel, roll roughness 3.2 μm Ra (discharge dull processing), intermediate roll shift so that the plate shape is flat Fig. 3 shows the experimental results when a 100K forged steel roll is used in the temper rolling mill shown in Fig. 4, as shown in Fig. 3. In addition, when the work roll diameter is, for example, 600 mm, the line load exceeds the range of the present invention, and therefore, the conventional 6-high rolling mill having a work roll having a diameter of 600 mm, for example, is a conventional 6-high rolling mill. It is obvious that the line load exceeds the range of the present invention when using a roll, and when the work roll diameter exceeds 1200 mm, such a large 6-high rolling mill does exist. Since there is no, it was not possible to experiment.

  In the case of the example of the present invention, the surface roughness of the rolled plate was 1.09 μmRa, and a product having a surface roughness of 1.0 to 1.2 μmRa could be produced. However, in the case of the prior art, the surface roughness of the rolled sheet is 0.85 μmRa, and a product having a target surface roughness of 1.0 to 1.2 μmRa cannot be made from this material. Further, in order to produce a product with a surface roughness of 1.0 to 1.2 μmRa, which is the target of the prior art, it is necessary that the elongation rate is 2.4% at the same roll roughness, and the roll roughness is 12 μmRa at the same elongation rate. In the former case, the mechanical properties and sheet thickness accuracy after rolling are lost, and in the latter case, the outer diameter of the discharge dull becomes too large, which impairs the design of the product. Therefore, in the case of the prior art, it was necessary to build roughness in the cold tandem rolling process (performed by changing the roughness of the work roll), but it was impossible to build the roughness in the temper rolling process. On the other hand, it was confirmed that the present invention made it possible to build roughness in the temper rolling process.

  In addition, when rolling a 100K high-tensile material (plate thickness 1 mm, plate width 1020 mm, 0.2% proof stress 400 MPa, material surface roughness 0.9 μmRa obtained from a tensile test), a forged steel roll having a large diameter (roll diameter 1200 mm) Although it could not be rolled at the load limit, it was a large diameter carbide roll (roll diameter 1200 mm, roll surface sleeve Young's modulus 560 GPa, surface roughness 3.1 μmRa dull roll. Sleeve thickness 100 mm, length 1800 mm. As a result of using a WC (caking material: Co) sleeve ring by cold fitting into a steel roll structure to produce a dull roll, surface roughness after rolling in this case can be achieved. Was about 1.18 μmRa. Furthermore, when a hot-dip galvanized steel sheet (thickness 1 mm, sheet width 980 mm, 0.2% proof stress 260 MPa) was rolled with a forged steel roll by changing the material, there was a case where an earlobe was generated at the edge in the conventional technique. On the other hand, no earlobe was generated in the present invention.

(Example 2) The effect of the present invention was confirmed by giving another example (Example 2) of the present invention. In Example 2, the temper rolling mill, the diameter of the work roll, the trunk length, the material, the roughness, and the coil used are the same as those in Example 1. The surface roughness of the coil after temper rolling at an elongation of 0.5% was investigated. In addition, the roll shift amount of the upper and lower work rolls was adjusted by arranging work rolls with asymmetrical crowns in the width direction of the board so that the plate shape is flat and symmetrical in the vertical point. Also, as a conventional technology, a normal 6-high rolling mill (work roll diameter 480 mm, body length 1800 mm, material is forged steel, roll roughness 3.2 μm Ra (discharge dull processing), intermediate roll shift so that the plate shape is flat And the work roll bender was adjusted and rolled under the same rolling conditions.

  In the case of the example of the present invention, the surface roughness of the rolled plate was 1.09 μmRa, and a product having a surface roughness of 1.0 to 1.2 μmRa could be produced. However, in the case of the prior art, the surface roughness of the rolled sheet is 0.85 μmRa, and a product having a target surface roughness of 1.0 to 1.2 μmRa cannot be made from this material. Further, in order to produce a product with a surface roughness of 1.0 to 1.2 μmRa, which is the target of the prior art, it is necessary that the elongation rate is 2.4% at the same roll roughness, and the roll roughness is 12 μmRa at the same elongation rate. In the former case, the mechanical properties and sheet thickness accuracy after rolling are lost, and in the latter case, the outer diameter of the discharge dull becomes too large, which impairs the design of the product. Therefore, in the case of the prior art, it was necessary to build roughness in the cold tandem rolling process (performed by changing the roughness of the work roll), but it was impossible to build the roughness in the temper rolling process. On the other hand, it was confirmed that the present invention made it possible to build roughness in the temper rolling process.

  Also, when rolling 100K high-tensile material (plate thickness 1mm, plate width 1020mm, 0.2% proof stress 400MPa, material surface roughness 0.9μmRa obtained from tensile test), large diameter forged steel rolls cannot be rolled at the load limit. However, a large-diameter carbide roll (a roll surface sleeve with a Young's modulus of 560 GPa and a surface roughness of 3.1 μmRa is a dull roll with a sleeve thickness of 100 mm and a length of 1800 mm of WC (bonding material: Co). As a result of using a dull roll by cooling and fitting the ring to a steel roll structure, a surface roughness after rolling of about 1.19 μmRa is obtained, and the conventional work roll diameter, work roll material and work roll roughness are obtained. Rolling with the same degree of roughness was achieved. Furthermore, when the hot-dip galvanized steel sheet was rolled with a forged steel roll while changing the material, there was an earlobe generated at the edge portion in the prior art, whereas no earlobe was generated in the present invention.

  As described above, the method of controlling the plate shape by the roll cross method and the roll shift method in the two-high rolling mill has been described. However, as another shape control method, a method using a work roll bender in a four-high rolling mill may be used. However, because the load fulcrum position and the bender fulcrum position need to be shifted, the work roll chock needs to be divided, the length of the neck part needs to be longer, etc., the equipment becomes larger than the roll cross type and roll shift type equipment, and the shape control capability However, it is possible to control the shape of the plate to some extent.

DESCRIPTION OF SYMBOLS 1, 2 Work roll 3 Rolling load detection apparatus 4 Electric reduction device 5 Hydraulic reduction device 6, 7 Roll cross mechanism or roll shift mechanism 8 Lubrication supply nozzle 9 Temper rolling mill
10, 11 Touch roll 12, 13 Bridle roll 14, 15 Deflector roll S Metal strip

Claims (6)

  In a temper rolling mill, a dull work roll having a surface roughness expressed by arithmetic mean roughness of 1 μm Ra or more and 10 μm Ra or less, a roll diameter of 1000 mm or more and 1400 mm or less, and a 0.2% proof stress obtained from a tensile test is 350 MPa. A temper rolling mill having a function of rolling at a rate of elongation of 0.2% to 3.0% when rolling the following metal strip. In a temper rolling mill, a surface roughness represented by arithmetic average roughness is 1 μm Ra or more and 10 μm Ra or less, and a roll diameter is 1000 mm or more and 1400 mm or less, and a dull work roll is provided.
When rolling a metal strip having a 0.2% proof stress of 350 MPa or less obtained from a tensile test, the Young's modulus of the roll surface layer is rolled on a dull work roll, and when rolling a metal strip having a 0.2% proof stress exceeding 350 MPa obtained from a tensile test. Can be replaced with 450GPa or more dull work rolls,
A temper rolling mill having a function of rolling at an elongation of 0.2% to 3.0%.   The temper rolling mill according to claim 1 or 2, wherein the temper rolling mill is a two-stage rolling mill, and is provided with a mechanism that intersects upper and lower work rolls.   The temper rolling mill according to claim 1 or 2 is a two-stage rolling mill, wherein work rolls with asymmetric crowns in the sheet width direction are arranged symmetrically in the vertical direction, and the upper and lower work rolls are arranged in the sheet width direction. A temper rolling mill, characterized in that a mechanism for moving to is provided.   In the temper rolling method, a 0.2% proof stress determined by a tensile test is 350 MPa using a dull work roll having a surface roughness expressed by arithmetic mean roughness of 1 μm Ra or more and 10 μm Ra or less and a roll diameter of 1000 mm or more and 1400 mm or less. A temper rolling method, wherein the following metal strip is rolled at an elongation of 0.2% to 3.0%. In the temper rolling method, a surface roughness represented by arithmetic average roughness is 1 μmRa or more and 10 μmRa or less, and a roll diameter is 1000 mm or more and 1400 mm or less.
When rolling a metal strip having a 0.2% proof stress of 350 MPa or less obtained from a tensile test, a dull work roll is used.
When rolling a metal strip having a 0.2% proof stress exceeding 350 MPa obtained from a tensile test, a dull work roll having a Young's modulus of the roll surface layer of 450 GPa or more is used.
A temper rolling method comprising rolling at an elongation of 0.2% or more and 3.0% or less.

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