JP2013185161A - Temperature equalizing roller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a temperature equalizing roller which can stably equalize temperature distribution of a roller surface.SOLUTION: A temperature equalizing roller has a multi-layered structure composed of an inner cylinder 1 and an outer cylinder 6 and includes a circumferentially-spiral structure (spiral blade) 9 which is provided between the inner cylinder 1 and the outer cylinder 6, at interval in a roller-length direction. The temperature equalizing roller is configured in such a way that: the inner cylinder 1 does not rotate and the outer cylinder rotates or rotational speed of the inner cylinder 1 and that of the outer cylinder 6 are different; the inside of the inner cylinder 1 is formed in a space 2 having such a form that working fluid does not stay (for example, the tapered space); the inner space 2 of the inner cylinder and the surface of the inner cylinder (the outer surface of the inner cylinder) 8 are connected together; and in the roll, as the working fluid (heating medium), material with high thermal conductivity (liquid metal or molten metal) is sealed.

Description

  The present invention relates to a soaking roll that makes the roll surface temperature distribution uniform.

  In a production line using rolls, there are many situations where temperature uniformity on the roll surface is required.

  For example, in a continuous annealing furnace of a steel production line, a roll called a hearth roll is installed in the furnace in order to allow the steel strip to pass through the furnace stably. In order to prevent meandering in the width direction of the steel strip, this hearth roll is often provided with a center convex crown on the roll surface. This is because the steel strip can be automatically centered in the center of the roll body length by the convex crown of the roll when tension is applied.

  However, in the heating zone of the continuous annealing furnace, the steel strip temperature entering the heating zone is lower than the ambient temperature of the heating element, so the center part of the hearth roll is cooled by the steel strip and the center in the trunk length direction becomes a concave inverted crown. As a result, meandering of the steel strip was promoted, and the steel strip contacted the furnace wall or fractured in the furnace, leading to serious troubles.

  On the other hand, in the cooling zone of the continuous annealing furnace, the steel strip temperature entering the cooling zone is higher than the ambient temperature of the cooling zone, so the center of the hearth roll is heated by the steel strip and applied to the original center in the longitudinal direction. The raised crown was further emphasized by heating, and as a result, the steel strip buckled at the center of the roll, which caused wrinkles and a heat buckle, which also caused serious problems in production.

  In addition, with respect to the crown previously given to the roll, the crown which arises by the temperature change by the contact of a steel strip etc. is called a thermal crown.

  Therefore, as a countermeasure, it is possible to maintain the roll crown originally applied by making the temperature distribution in the barrel length direction of the hearth roll uniform, suppressing the occurrence of the concave or convex thermal crown in the center in the barrel length direction. It is effective and the following techniques are disclosed.

  For example, in Patent Document 1, a porous material is provided on the inner surface of a hearth roll, the inside of the roll is evacuated, and a working fluid such as sodium is enclosed inside to provide a uniform temperature distribution in the axial direction. That is, the roll itself is configured like a heat pipe so that the temperature distribution in the body length direction is automatically made uniform.

  In Patent Document 2, a double sleeve is fitted (fixed), and cooling water is supplied to a groove provided in a straight line in the cylinder length direction with a space in the circumferential direction between the inner sleeve and the arbor body part. It shows a roll that is made to flow and makes the roll crown variable, and is divided into a circumferential groove in the forward direction and a circumferential groove in the reverse direction, and the cooling water flows separately.

JP-A-6-279836 JP 59-153508 A

  However, as a result of investigations by the present inventors, it has been found that the techniques described in Patent Documents 1 and 2 have the following problems.

  First, in Patent Document 1, it is difficult to maintain a stable vacuum for a long period of time, and in heat transfer using passive physical changes such as evaporation / condensation of the working fluid, tracking of the generated temperature changes is followed. Since the property is not high, there is a problem that the roll surface temperature is difficult to be uniform.

  Moreover, in patent document 2, when the temperature of the steel strip passed by the roll is changed, the direction in which the cooling water flows is limited to be linear in the body length direction, so the roll surface temperature is set in the circumferential direction. It is difficult to make it sufficiently uniform, and the roundness of the roll deteriorates due to the thermal crown, making it difficult to pass the plate, and the steel strip and the roll slip to cause wrinkles.

  This invention is made | formed in view of the above situations, and it aims at providing the soaking | uniform-heating roll which can make uniform the surface distribution of a roll body length direction and the circumferential direction stably. Is.

  As a result of various studies to solve the above problems, the present inventors have obtained the following knowledge.

  The inside of the roll forces the working fluid rather than using natural convection or passive physical phenomena such as evaporation / condensation of the working fluid or flowing the working fluid in one direction. Heat is transferred more efficiently by convection or forced agitation, and soaking effect on the roll surface is higher. For that purpose, the roll has a multiple structure consisting of an inner cylinder and an outer cylinder, a space is provided between the inner cylinder and the outer cylinder in the longitudinal direction, and a spiral structure is provided in the circumferential direction, the inner cylinder is stationary and the outer cylinder is rotated, Or it is good not to make the rotation speed of an inner cylinder and an outer cylinder correspond. Further, it is more preferable to provide a tapered space or a diagonally downward space inside the inner cylinder, and connect the space and the inner cylinder surface with a hole or an opening. Furthermore, it is better to use a high thermal conductivity material such as liquid metal or molten metal as the working fluid.

  The present invention has been made based on the above findings and has the following characteristics.

  [1] In order to make the roll surface temperature distribution uniform, working fluid is sealed inside the roll, and a multiple structure consisting of an inner cylinder and an outer cylinder is formed. A temperature equalizing roll characterized in that a spiral structure is provided at intervals in the direction, the inner cylinder is not rotated and the outer cylinder is rotated, or the rotational speeds of the inner cylinder and the outer cylinder are different.

  [2] The temperature equalizing roll according to [1], wherein the inner cylinder is a space in which the working fluid does not stay, and the space and the inner cylinder surface are connected to each other.

  [3] The temperature equalizing roll according to [1] or [2], wherein the working fluid is a liquid metal or a molten metal having high thermal conductivity.

  In the present invention, the roll surface distribution can be made uniform stably. Therefore, for example, when the present invention is applied to a hearth roll of a continuous annealing furnace, the roll surface temperature is made uniform, the thermal crown is suppressed, and the occurrence of steel strip meandering and heat buckle is greatly reduced, resulting in stable communication. A board becomes possible, and a product yield and an equipment operation rate can be improved.

It is roll width direction sectional drawing explaining the roll structure in one Embodiment of this invention, and the flow of a working fluid (heat medium). It is a figure explaining the position of the hearth roll made into the application object in the Example of this invention.

  The best embodiment of the present invention will be described.

  The essence of the present invention is to make the temperature distribution on the roll surface uniform by moving the working fluid (heat medium) inside the roll surface at a high speed with forced convection and forced stirring.

  Therefore, in the best embodiment of the present invention, as shown in FIG. 1, a multi-layered structure composed of an inner cylinder 1 and an outer cylinder 6 is formed, and a spiral structure (in the barrel length direction) is formed between the inner cylinder 1 and the outer cylinder 6. The inner cylinder 1 does not rotate and the outer cylinder 6 rotates, or the inner cylinder 1 and the outer cylinder 6 have different rotational speeds. The fluid is forcibly agitated and can be moved at a high speed. Further, the inside of the inner cylinder 1 is a space (for example, a tapered space) 2 in which working fluid does not stay, and the inner cylinder inner space 2 and the inner cylinder surface (inner cylinder outer surface) 8 are connected. In the roll, a high thermal conductivity material (liquid metal or molten metal) is sealed as a working fluid (heat medium) and always flows at a high speed in the roll use temperature range. In FIG. 1, 1a is an inner cylinder shaft, and 6a is an outer cylinder shaft.

  First, the operation of the high thermal conductivity material (heat medium) will be described with reference to FIG. In the roll use temperature range, at least the heat medium is a fluid.

  (S1) As indicated by A in FIG. 1, the heat medium flows diagonally downward along the wall surface 3 of the inner space 2 of the inner cylinder 1 by gravity.

  (S2) As indicated by B in FIG. 1, the heat medium that has reached the lowest point of the inner space 2 of the inner cylinder 1 passes through the opening 4 connecting the inner cylinder inner space 2 and the inner cylinder outer surface 8 to the inner surface of the outer cylinder. 5

  (S3) Since the outer cylinder 6 is rotating, the heat medium is also dragged to the inner surface 5 of the outer cylinder, and sticks to the inner surface 5 of the outer cylinder due to centrifugal force and starts to rotate.

  (S4) As indicated by C in FIG. 1, the heat medium advances in the roll body length direction while rotating along the helical structure (spiral blade) 9 between the outer cylinder 6 and the inner cylinder 1. . During this time, since the outer cylinder and the inner cylinder have different rotational speeds, a shearing force is applied to the heat medium, and the heat medium is forcibly agitated.

  (S5) As indicated by D in FIG. 1, the heat medium that has reached the end of the roll cylinder length flows out from the opening 7 connecting the inner cylinder outer surface 8 and the inner cylinder inner space 2 to the inner cylinder inner space 2. During this time, the heat medium is forcibly agitated, and forced convection also occurs due to the temperature difference between the heat medium flowing into the space 2 and the heat medium already stored while flowing in the inner cylinder internal space 2.

  (S6) Hereinafter, the above (S1) to (S5) are repeated, and the heat medium circulates inside the roll.

  Next, (S1) to (S5) will be described in detail.

  (S1) The inner cylinder 1 is not rotated and the outer cylinder 6 is rotated, or the rotational speeds of the inner cylinder 1 and the outer cylinder 6 are different from each other, but the inner cylinder 1 is preferably not rotated. In addition, when the rotational speeds of the inner cylinder 1 and the outer cylinder 6 are different, the rotational speed of the inner cylinder 1 may be slower than the rotational speed of the outer cylinder 6. And although the shape of the inner cylinder internal space 2 is not ask | required, it is set as the shape where a heat carrier does not stay. For example, in the case of a tapered space as shown in FIG. 1, the heat medium flows downward along the tapered surface by gravity. Since the inner cylinder inner space 2 plays a role of moving the heat medium in the roll body length direction by the gravitational action, it is reasonable to make the inner cylinder 1 non-inverted unless there is a special reason. When the inner cylinder 1 is also rotated, a plurality of openings 4 that communicate with the inner surface 5 of the outer cylinder and openings 7 that communicate with the inner space 2 of the inner cylinder may be provided in the inner circumferential direction. Thereby, the heat medium flows easily without accumulating between the inner cylinder 1 and the outer cylinder 6 or in the inner cylinder inner space 2.

  (S2) The opening 4 is preferably in the vertical direction. This is because the heat medium that has reached the opening 4 flows out quickly.

  (S3) Since the outer cylinder 6 rotates according to the production speed, it is a moving wall when viewed from the heat medium. The heat medium on the inner surface 5 of the outer cylinder starts to move together with the inner surface 5 of the outer cylinder due to viscosity and receives centrifugal force, so that it sticks to the inner surface 5 of the outer cylinder and starts to rotate.

  (S4) A space between the inner cylinder 1 and the outer cylinder 6 is a spiral channel (spiral channel). Basically, a spiral blade 9 is fixed to the inner surface 8 of the outer cylinder. If there is nothing, the heat medium sticks to the inner surface 5 of the outer cylinder at the position where it flows out of the inner cylinder 1 and accumulates on the spot and rotates in the circumferential direction. In particular, it proceeds in the longitudinal direction in the spiral flow path. Here, the direction of the spiral is set so that the heat medium travels in a direction opposite to the body length direction in which the heat medium has traveled through the inner cylinder internal space 2. In addition, if the gap between the inner cylinder 1 and the outer cylinder 6 is too large, effective transport of the heat medium in the body length direction cannot be performed. Therefore, it is determined in consideration of the amount of heat medium enclosed, the roll rotation speed, and the like. .

  (S5) The heat medium that has reached the end of the roll cylinder in the spiral flow path flows out again from the opening 7 provided in the inner cylinder internal space 2. For the same reason as described in (S2), it is desirable that the opening 7 be in the vertical direction.

  And as a characteristic calculated | required by a heat medium, in order to conduct heat | fever effectively, it has high thermal conductivity, and it is easy to stick to an outer cylinder inner surface, ie, there exists a high viscosity. Thus, liquid metal or molten metal can be a strong candidate.

  Here, as the liquid metal, in addition to mercury, a commercially available grease having improved safety is preferable. The molten metal is preferably a metal that liquefies even at the minimum use temperature of the roll, and in the case of a steel strip continuous annealing furnace, tin, tin alloy, zinc, zinc alloy, lead, lead alloy, and the like are preferable.

  Although the present invention is effective for uniforming the surface temperature of the hearth roll for a continuous annealing furnace in a steel production line, the present invention is not limited to the above-described embodiment, and does not depart from the gist thereof. Various modifications can be made.

  As an example of the present invention, the present invention was applied to a hearth roll for a continuous annealing furnace in a steel production line. The implementation conditions are as follows.

・ Used place: Continuous annealing furnace Hearth roll at the heating zone outlet (Fig. 2)
・ Strip length of steel strip: 10,000m in total
Steel strip width: 1250mm
Steel strip temperature: 680-720 ° C
-Furnace temperature: 800-900 ° C
・ Heath roll outer diameter: Φ600mm
・ Encapsulated heat medium: Zinc ・ Heath roll surface temperature measurement position: The following two locations The center of the hearth roll length direction, 50 mm inside from the steel strip contact end of the hearth roll inside the barrel length direction and the above hearth roll length direction A temperature deviation ΔT inside 50 mm was calculated in the length direction from the center and the steel strip contact end of the hearth roll.

  The results were as follows.

First, ΔT = 50 ° C. for a conventional hearth roll without internal cooling. In addition, in the hearth roll provided with a gap in the circumferential direction described in Patent Document 2 and having a groove linearly in the body length direction, ΔT = 30 ° C. On the other hand, in the hearth roll to which the present invention is applied, ΔT could be reduced to 10 ° C., and the surface temperature was made uniform. As a result, the thermal crown was suppressed, and there was almost no wrinkling of the steel strip due to the meandering of the steel strip or the occurrence of heat buckles, which significantly improved the product yield and equipment availability.

DESCRIPTION OF SYMBOLS 1 Inner cylinder of roll 1a Inner cylinder axis | shaft 2 Inner cylinder internal space of roll 3 Wall surface of inner cylinder inner space of roll 4 Opening which connects inner cylinder inner space of roll and outer surface of inner cylinder 5 Inner cylinder inner surface of roll 6 Out of roll Cylinder 6a Outer cylinder shaft 7 Opening part connecting inner cylinder outer surface of roll and inner cylinder inner space 8 Inner cylinder outer surface of roll (inner cylinder surface)
9 Spiral feather

Claims (3)

  In order to make the roll surface temperature distribution uniform, working fluid is sealed inside the roll, and it has a multiple structure consisting of an inner cylinder and an outer cylinder. A soaking roll provided with a spiral structure in the circumferential direction, the inner cylinder is stationary and the outer cylinder rotates, or the inner cylinder and the outer cylinder have different rotational speeds.   2. The temperature equalizing roll according to claim 1, wherein the inside of the inner cylinder is a space in which the working fluid does not stay, and the space is connected to the surface of the inner cylinder.   The temperature equalizing roll according to claim 1 or 2, wherein the working fluid is a liquid metal or a molten metal having a high thermal conductivity.

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