JP3629127B2 - Equipment for continuous annealing of strips - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention mainly relates to a continuous annealing facility for strips after cold rolling, and aims to stably produce high-quality annealed products. Here, the band-like body is subjected to tin plating, galvanization, surface coating, etc. as necessary after continuous annealing, and finally used for manufacturing cans, steel furniture, automobiles, electrical products, etc. Say what is called.
[0002]
[Prior art]
In general, the tension of the cold-rolled steel strip in the continuous annealing equipment is preferably as large as possible for the purpose of preventing walks and fluttering, and as small as possible for the purpose of preventing heat buckles and preventing reduction of the plate width in the high temperature part. Further, in the annealing of the cold-rolled magnetic steel strip, this tension is preferably as small as possible for the purpose of preventing magnetic deterioration.
[0003]
Due to this conflicting requirement, the tension of the strip is reduced in a heating furnace or a soaking furnace where the strip becomes high in normal operation, and in the cooling zone or overaging zone where the temperature of the strip and the strip are relatively low. Measures are taken to increase the tension.
[0004]
Such a tension distribution can be obtained by finely adjusting and controlling the speed of the hearth roll. Furthermore, when it is desired to change the tension suddenly at a certain point, a bridle roll is generally provided.
[0005]
FIG. 2 is a side view of a cold-rolled steel strip continuous annealing facility showing an example of this, and a bridle roll 2 is provided in the furnace. A roll group comprising a hearth roll 3 arranged in each furnace 4-7 so as to guide the strip 1 supplied into each furnace 4-8 from the entry side to the exit side; A bridle roll 2 is provided immediately before the strip 1 passed through the furnace 5 enters the quenching furnace 6 where it is exposed to a high-speed gas jet, and the tension of the strip 1 becomes a large value after passing through the bridle roll 2. Then, it passes through the subsequent quenching furnace 6, overaging furnace 7, and final cooling furnace 8.
[0006]
Of course, the bridle roll 2 and the hearth roll 3 provided for such a purpose should surely restrain the strip 1 and do not cause slip. However, in reality, it has been found that the bridle roll 2 and the hearth roll 3 often slip, particularly when the thickness of the belt-like body 1 is reduced, and the original function is not exhibited.
[0007]
As an improvement measure, there is a measure disclosed in the republished patent publication WO093 / 24664, in which the surface pressure of the roll is set to 10 kpa (kilopascal).
[0008]
[Problems to be solved by the invention]
In the continuous annealing equipment in which the tension of the strip 1 is relatively large, the roll surface pressure of the bridle roll 2 and the hearth roll 3 is set to 10 kpa (kilopascal) or more, and the slip is eliminated if the strip 1 is reliably restrained. However, it has been newly found that the slip in the continuous annealing equipment with a low tension of the strip 1 cannot be improved, and the bridle roll 2 and the hearth roll 3 often cause slip and do not exhibit their original functions.
[0009]
An object of the present invention is to solve such problems and to provide a continuous annealing facility for a strip-like body capable of fully exhibiting the functions of a bridle roll and a hearth roll and capable of stable operation of an annealing furnace.
[0010]
[Means for Solving the Problems]
To achieve the above object, the inventors bridle roll and hearth rolls of the surface pressure, as well as to investigate the relationship between the friction coefficient and the slip between the surface of the roll and the strip, superposed ingenuity results below ( According to the present invention of 1) and (2), the above-mentioned problems have been solved, and the functions of bridle rolls and hearth rolls have been fully demonstrated to enable stable operation of the annealing furnace.
[0011]
(1) In a continuous annealing facility for strips having a group of rolls arranged in the annealing facility so as to guide the strip supplied to the annealing facility from the entry side to the exit side, at least one of the roll groups The unit tension of the belt on the roll entry side (pressing roll exit side when pressed with a pressing roll) is σ1, and the roll unit is on the roll exit side (pressing roll entry side when pressing with a pressing roll). When the unit tension of the strip is σ2, the thickness of the strip is h, the diameter of the roll is D, and the friction coefficient between the roll surface and the strip is μ, the range of the thickness of the strip, unit tension, etc. For each of the conditions, among the rolls having a diameter D and a friction coefficient μ such that the unit frictional force f of the roll contact surface obtained by the equation (I) is 750 pa (Pascal) for each of the conditions, Equation 2 Roll contact represented by formula (I) Unit frictional force f of the surface is 750 Pa (pascal) or [where the roll surface pressure p = h (σ1 + σ2) / D is less than 10 kpa] and characterized by comprising diameter D such that the roll of the friction coefficient μ Continuous annealing equipment for strips.
[0012]
[Expression 2]
f = μh (σ1 + σ2) / D (I)
[0013]
(2) The continuous annealing equipment for a strip-shaped body according to (1), wherein at least one roll in the roll group is a bridle roll or a hearth roll .
[0014 ]
[0015 ]
[0016 ]
[0017 ]
[0018 ]
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
[0020]
The present inventor started by using various strips, changing the tension of the strips in various ways, and investigating the occurrence limit of slip in bridle rolls of various materials and roll diameters.
[0021]
In terms of engineering, as shown in FIG. 4, the entry side tension of the bridle rolls 2a to 2c is T1, the exit side tension is T2, the winding angle of the strip 1 on the bridle rolls 2a to 2c is θ (= θ1 + θ2 + θ3), roll When the friction coefficient between the surfaces 2a to 2c and the belt-like body 1 is μ, the maximum tension T2 that does not cause a slip is expressed by Equation (II) .
[0022]
[Equation 3]
T2 = T1 · exp (μθ) (II)
[0023]
FIG. 5 shows an example of the bridle rolls 2a to 2c pressed by the pressing rolls 11a and 11c. At this time, T1 is the tension on the exit side of the pressing roll 11a of the entry bridle roll 2a, and T2 is the tension on the entry side of the pressing roll 11c of the exit bridle roll 2c. The same applies when one of the entry / exit sides of the bridle rolls 2a to 2c is pressed by the pressing roll.
[0024]
In any case, in other words, the tension magnification T2 / T1 is uniquely determined by the parameter μ and is not related to the absolute value of the tension. However, in an actual bridle roll, even if this tension magnification is the same, slipping tends to occur when the absolute value of the tension becomes small. That is, the friction coefficient μ is considered to be affected by the tension.
[0025]
The number of bridle rolls is not limited and may be one. The number is determined from θ obtained by reverse calculation of the formula (II).
[0026]
In an actual continuous annealing furnace, regarding a hearth roll and a bridle roll having different diameters and friction coefficients μ, where D is the bridle roll diameter and W is the width of the belt-like body, the slip generation limit is expressed by Formula 4 (III) It was found that it is defined by the unit frictional force f ( Formula 5 (IV) ) of the roll contact surface, which is the product of the defined surface pressure and the friction coefficient μ.
[0027]
[Expression 4]
p = (T1 + T2) / (DW) (III)
[0028]
[Equation 5]
f = pμ = μ (T1 + T2) / (DW) (IV)
[0029]
The data shown in FIG. 1 is for a strip made of a smooth steel bridle roll, a hearth roll, a roll made of rubber or a nonwoven fabric, a cold rolled steel strip, and a cold rolled silicon steel strip. And obtained under the conditions of a line speed of 50 to 600 mpm. The coefficient of friction is a measured value at the slip limit in each combination of roll and strip.
[0030]
As is apparent from FIG. 1, there is a transition point near the unit friction force f = 750 pa (Pascal) of the roll contact surface (hereinafter, the unit friction force f of the roll contact surface at this transition point is expressed as the roll contact surface). The limit unit frictional force fc). In the region where the unit frictional force f of the roll contact surface is fc or more, the bridle roll and the hearth roll are in a state of normally restraining the belt-like body, and in the region of fc or less, the slip state, that is, the friction is in a kinetic friction state. In order for the bridle roll and the hearth roll to function normally, the roll material (surface) and diameter must be determined so that the unit frictional force f of the roll contact surface is fc or more. Further, it can be seen from FIG. 1 that by optimizing the roll material (surface), the bridle roll and the hearth roll can normally restrain the belt-like body even if the roll surface pressure is less than 10 kpa (Pascal).
[0031]
The hearth roll is generally intended to be conveyed without changing the tension of the belt-like body. However, as can be seen from FIG. 1, when the unit frictional force f = 750 pa (Pascal) or less on the roll contact surface, the dynamic friction state occurs, and slippage occurs due to a slight difference in tension before and after the hearth roll. The phenomenon of slipping even though there is almost no tension difference is strange at first glance, but the control device of the motor that drives the hearth roll generally has no means of knowing the true speed of the belt, so the roll peripheral speed is the command value. Such a phenomenon occurs because of control (same as bridle roll). In addition, the roll peripheral speed also promotes this phenomenon because the diameter of the hearth roll thermally expanded in a high-temperature furnace is not accurately known and does not follow the command. The presence of such slipping is the occurrence of wrinkles on the strip or the build-up on the hearth roll surface due to permanent slipping (iron warts sticking, which also causes wrinkles of the strip). However, the present invention can solve this problem by selecting an appropriate material (surface) and diameter of the roll so as to be not less than the limit unit frictional force of the roll contact surface.
[0032]
Since the normal operation is performed so that the unit tension σ of the belt-like body is constant, the equation (IV) is rewritten using the relationship of tension T = σhW as shown in Equation 6 (V) .
[0033]
[Formula 6]
f = μh (σ1 + σ2) / D (V)
[0034]
When the surface finish (roughness, etc.) of the bridle roll or hearth roll changes with use, it is necessary to design with the numerical value of the lower limit value (before roll replacement) within the use limit.
[0035]
If the line speed and the friction coefficient between the roll surface and the belt are greatly different, the limit unit friction force fc of the roll contact surface determined by FIG. 1 may change, but the bridle roll or the hearth roll is changed to the limit unit friction of the roll contact surface. There is no change in the basic idea of deciding to be more than power.
[0036]
Note that the concept of selecting a roll having a friction coefficient and a diameter so that the limit unit frictional force fc on the roll contact surface is set to a limit value that does not cause slipping is not limited to bridle rolls as described above. Applicable.
[0037]
When the hearth roll diameter cannot be reduced due to equipment restrictions, such as a heating furnace equipped with a radiant tube, it is effective to increase the friction coefficient of the roll surface within a range that does not cause quality problems.
[0038]
In addition, if there is no roll with an appropriate coefficient of friction, it is necessary to consider the design and adjustment of the hearth roll drive system so as not to apply excessive driving force exceeding the torque required to transport the hearth roll. For example, it is also effective to limit the speed command common to the furnace so that a speed error of a certain value (several mpm) or more does not occur, or to have an appropriate drooping characteristic.
[0039]
In addition, this invention is not limited to the annealing equipment of a cold-rolled steel strip and a cold-rolled silicon steel strip, It is applied about the processing equipment of all the strip | belt bodies.
[0040]
【Example】
Examples are shown below.
[0041]
[Example 1]
The design example of the bridle roll in the furnace of the continuous annealing equipment of the cold rolled steel strip according to the present invention is shown below.
[0042]
Units tension σ1 = 0.7kg / mm ² of the strip in the bridle roll entry side, a unit tension σ2 = 1.2kg / mm ² of the outgoing side, and a thickness h = 0.25 mm of the strip. Each roll is made of steel in terms of product quality and is smoothly finished, and the strip is also a cold-rolled steel strip that has been smoothly finished. The friction coefficient between the surface of each roll and the strip is measured. 09. From the formula (II) and the equipment layout, the number of rolls is 3, the winding angle in each roll is 180 degrees, and the tension magnification in each roll is constant value = σ2 / σ1 = 1.2 . Substituting the limit unit frictional force fc = 750 pa of the roll contact surface into the formula (V) to obtain the respective roll diameters D1, D2, and D3, D1 = 460 mm, D2 = 550 mm, and D3 = 660 mm.
[0043]
Actually, the roll diameters are different from each other in terms of production and maintenance, so all roll diameters are set to 460 mm or less from the safety side.
[0044]
[Example 2]
A design example of the hearth roll in the furnace of the continuous annealing equipment for the cold rolled steel strip according to the present invention will be shown below. The conditions for preventing slipping are the same as the bridle roll of the first embodiment.
[0045]
In the hearth roll, the unit tension of the strips before and after the same is generally the same (σ1 = σ2), σ1 = σ2 = 0.7 kg / mm ² , and h = 0.25 mm. Each roll is made of steel and is a cold-rolled steel strip with a smooth finish, and the friction coefficient between the surface of each roll and the strip is 0.09. . It can be substituted into the formula (V) to apply a single place frictional force fc = 750pa. By substituting the limit unit frictional force fc = 750 Pa of the roll contact surface Formula (V), at the Request B Lumpur diameter D, equal to or less than 420 mm.
[0046]
[Example 3]
An example of the design of a bridle roll between the furnace and the exit side looper of the continuous decarburization annealing equipment for the directional cold-rolled silicon steel strip according to the present invention is shown below. FIG. 3 shows drawings before and after the furnace of the continuous decarburization annealing equipment for the directional silicon steel strip to which the present invention is applied.
[0047]
Units tension σ1 = 0.5kg / mm ² of the strip in the bridle roll entry side, a unit tension σ2 = 1.1kg / mm ² of the outgoing side, and a thickness h = 0.23 mm of the strip. Each roll is made of rubber, and its surface is smoothed by a change with time before roll replacement. Moreover, a strip | belt body is a decarburization annealing board, The surface is oxidized. The coefficient of friction between each roll and the surface of the strip was set to 0.105, which is a measurement result. From the formula (II) and the equipment layout, the number of rolls = 2, the winding angle in each roll = 220 degrees, and the tension magnification in each roll was set to a constant value = σ2 / σ1 = 1.5. Substituting the limit unit frictional force fc = 750 pa of the roll contact surface into the formula (V) to obtain the respective roll diameters D1 and D2, D1 = 400 mm and D2 = 600 mm.
[0048]
Actually, since the roll diameters are different from each other in terms of production and maintenance, all roll diameters are set to 400 mm or less in view of safety.
[0049]
[Example 4]
Another example of the design of the bridle roll between the furnace and the exit side looper of the continuous decarburization annealing equipment for the directional silicon steel strip according to the present invention is shown below.
[0050]
Units tension σ1 = 0.3kg / mm ² of the strip in the bridle roll entry side, a unit tension σ2 = 1.5kg / mm ² of the outgoing side, and a thickness h = 0.15 mm of the strip. Each roll has a laminated structure of non-woven fabric, and its surface is rough even after long-term use. Moreover, a strip | belt body is a decarburization annealing board, The surface is oxidized. The coefficient of friction between each roll and the surface of the strip was set to 0.28, which is a measurement result. From the formula (II) and the equipment layout, the number of rolls = 2, the winding angle in each roll = 220 degrees, and the tension magnification in each roll was set to a constant value = σ2 / σ1 = 2.2. Substituting the limit unit frictional force fc = 750 pa of the roll contact surface into the formula (V) to determine the respective roll diameters D1 and D2 yields D1 = 530 mm and D2 = 1180 mm.
[0051]
Actually, since the roll diameters are different from each other in terms of production and maintenance, all roll diameters are set to 530 mm or less from the viewpoint of safety.
[0052]
【The invention's effect】
According to the present invention, the bridle roll and hearth roll provided in the continuous annealing equipment can surely exert the tension amplification action of the belt-like body which is the original function, and the highly stable operation of the continuous annealing equipment of the belt-like body is achieved. I can do it. In addition, it is possible to prevent a serious defect that wrinkles occur due to slippage between the belt and the roll, and the industrial value is tremendous.
[Brief description of the drawings]
FIG. 1 is a diagram showing measured values obtained by determining the relationship between roll surface pressure and friction coefficient of a bridle roll and a hearth roll and slip.
FIG. 2 is a schematic side view showing an arrangement example of in-furnace bridle rolls and hearth rolls in a continuous annealing facility for cold-rolled steel strips.
FIG. 3 is a schematic side view showing an arrangement example of bridle rolls and hearth rolls in a continuous decarburization annealing facility for cold-rolled silicon steel strip.
FIG. 4 is a diagram showing a general example of a relationship between a winding angle of a belt-like body around a bridle roll and a tension.
FIG. 5 is a diagram showing another example of the relationship between the winding angle of the belt-like body around the bridle roll and the tension.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Strip | belt body 2, 2a, 2b, 2c Bridle roll 3 Hearth roll 4 Heating furnace 5 Soaking furnace 6 Quenching furnace 7 Overaging furnace 8 Final cooling furnace 11a, 11c Pressing roll (theta), (theta) 1, (theta) 2, (theta) 3 To roll of strip | belt body Wrapping angle T1, T2 Band tension

Claims (2)

In a continuous annealing facility for a strip having a group of rolls arranged in the annealing facility so as to guide the strip supplied to the annealing facility from the entry side to the exit side, a roll of at least one roll in the roll group The unit tension of the band on the entry side (when pressed by the pressing roll, the exit side of the pressing roll) is σ1, and the unit tension of the band on the roll exit side (when pressing with the pressing roll, the pressing roll entry side) When the unit tension is σ2, the thickness of the strip is h, the diameter of the roll is D, and the friction coefficient between the roll surface and the strip is μ, the thickness of the strip, the unit tension, etc. Of the rolls having a diameter D and a friction coefficient μ such that the unit frictional force f of the roll contact surface obtained by Formula (I) is 750 pa (Pascal) for each condition, Formula 1 (I Of the roll contact surface represented by Position the frictional force f is 750 Pa (pascal) or [where the roll surface pressure p = h (σ1 + σ2) / D is less than 10 kpa] strip, characterized in that it comprises a diameter D such that the roll of the friction coefficient μ Equipment for continuous annealing of the body.

The continuous annealing equipment for strips according to claim 1, wherein at least one roll in the roll group is a bridle roll or a hearth roll.

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