Adiabatic Roll

Description

TECHNICAL FIELD

The present invention relates, in general, to an adiabatic roll and, more particularly, to an adiabatic roll which has low thermal conductivity, prevents reduction of the atmospheric temperature of a furnace; and has excellent deformability according to thermal expansion and shrinkage due to changes in temperature when the furnace is operated or stopped.

BACKGROUND ART

A conventional adiabatic roll is exemplified by a carrier roll in a furnace for preheating a slab before hot rolling, and an example is shown in FIG. 7. A plurality of heat-resistant rings 2 for supporting the load of a slab is welded into a water-cooled metal tub shaft 1. Studs 3 made of heat-resistant steel are welded into a portion of a surface of the metal tub shaft 1 other than ring-welded portions, and the resulting structure is coated with heat-resistant mortar 4, thereby achieving adiabatic construction of the adiabatic roll 6A. However, the above-mentioned constitution is not disclosed in patent documents.

DETAILED DESCRIPTION OF INVENTION Technical Problem

The conventional adiabatic roll having the above-mentioned constitution has the following problems.

In other words, since rings made of heat-resistant steel are directly welded into a metal tub shaft in the conventional adiabatic roll, heat loss through the water-cooled metal tub shaft is high, and the atmospheric temperature of a furnace is reduced or fuel consumption increases.

Furthermore, the temperature difference between surfaces of the heat-resistant rings and welded parts of the water-cooled metal tub shaft is high, thus resulting in high heat stress. Additionally, because the heat-resistant rings or the metal tub shaft are frequently separated from the welded parts, operation of the furnace must be stopped in order to change the roll.

Also, since an adiabatic structure is formed by applying a heat-resistant mortar, gaps are formed at interfaces of the heat-resistant rings and the mortar due to shrinkage that occurs when the mortar is dried and cured and due to thermal shrinkage caused by heating during operation of the structure. Heat permeates through the cracks into the water-cooled metal tub shaft, thus increasing fuel consumption and deteriorating the metal tub shaft, resulting in the reduced life of the roll.

Additionally, the heat-resistant mortar is easily removed due to a heating cycle associated with operation and stoppage of the furnace, thus making it necessary to renovate the mortar every three or four months.

Therefore, an object of the present invention is to provide an adiabatic roll in which heat-resistant rings and disks are not welded into a metal tub shaft but are fitted around the metal tub shaft, so that thermal conductivity is low, the adiabatic roll deforms in accordance with thermal expansion and shrinkage of the heat-resistant rings and thus prevents the formation of cracks and heat loss, the atmospheric temperature of a furnace is not lowered, fuel consumption is not increased, and resistance to impact is excellent.

TECHNICAL SOLUTION

The present invention provides an adiabatic roll. The adiabatic roll comprises a metal tub shaft 1 which has a through hole 1A for passing cooling water 20 therethrough, a plurality of heat-resistant rings 2 which is fitted around the metal tub shaft 1 and axially arranged at predetermined intervals between a fixed flange 5 and a movable flange 6 provided on a circumference of the metal tub shaft 1, and a plurality of disks 7 which is axially arranged between the heat-resistant rings 2. The heat-resistant rings 2 and the disks 7 are fitted around the metal tub shaft 1 without welding.

The present invention also provides an adiabatic roll characterized in that each of the heat-resistant rings 2 comprises first and second heat-resistant ring parts 2A, 2B which have different diameters and are concentrically arranged on the same vertical axis.

The present invention also provides an adiabatic roll characterized in that the first and second heat-resistant ring parts 2A, 2B of the heat-resistant rings 2 are joined together using a pair of ring-shaped plates 2D and round head screws 2E axially threaded into the ring-shaped plates 2D at a joint 2M thereof.

The present invention also provide an adiabatic roll characterized in that metal tub shaft key grooves 1d are formed on an external wall of the metal tub shaft 1, key grooves 2C are formed on internal walls of the heat-resistant rings 2, and the heat-resistant rings 2 are fitted around the metal tub shaft 1 by keys 10 which engage with the metal tub shaft key grooves 1d and the key grooves 2C.

The present invention also provides an adiabatic roll characterized in that metal tub shaft key grooves 1d are formed on an external wall of the metal tub shaft 1, key grooves 2C are formed on internal walls of the second heat-resistant ring parts 2B having relatively smaller diameters among the heat-resistant rings 2, and the second heat-resistant ring parts 2B are fitted around the metal tub shaft 1 by keys 10 which engage with the metal tub shaft key grooves 1d and the key grooves 2C.

The present invention also provides an adiabatic roll characterized in that the heat-resistant rings 2 are partially or entirely made of ceramic.

The present invention also provides an adiabatic roll characterized in that the external first heat-resistant ring part 2A of each of the heat-resistant rings 2 is made of nickel•cobalt or stainless steel, and the internal second heat-resistant ring part 2B of each of the heat-resistant rings 2 is made of ceramic.

EFFECTS OF INVENTION

An adiabatic roll of the present invention having the above-mentioned structure provides the following effects.

In the adiabatic roll of the present invention, heat-resistant rings which constitute an external surface part of the roll have excellent resistance to abrasion and impact, and can endure a load occurring in the course of carrying a slab during a hot rolling process and also endure abrasion and impact. Furthermore, the heat-resistant rings are fitted around a water cooled metal tub shaft, thereby reducing heat loss through the metal tub shaft due to heat conduction and preventing separation of the heat-resistant rings from the metal tub shaft due to heat stress. Additionally, heat-resistant rings having larger and smaller diameters are used in example 2, thus reducing thermal conductivity. SUS310S, instead of only using costly nickel•cobalt-based heat-resistant steel, is used to manufacture the rings, thus minimizing cost.

Furthermore, heat-resistant ceramic rings are used, thereby preventing heat loss due to heat conduction.

Furthermore, since disks made of inorganic material are used in an adiabatic part, no gaps or cracks occur at the interfaces of the heat-resistant rings with the adiabatic disks because of the cushiony disks, and direct inflow of heat to the water-cooled metal tub shaft is prevented. In addition, if nuts tightening the disks are loosened after the adiabatic roll is tested in example 1, the disks made of inorganic material are axially restored by 15 mm (25%) so as to sufficiently absorb 1.5 mm (calculated when the entire ring is at 1200° C.: linear expansion coefficient 17.8×10⁻⁶) which corresponds to the change in axial thermal expansion of the rings made of nickel-cobalt-based heat-resistant steel, thereby preventing the occurrence of gaps.

The present invention can be applied to an adiabatic roll for manufacturing iron and other carrier equipment at high temperatures.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a longitudinal sectional view of an adiabatic roll according to the present invention;

FIG. 2 is a longitudinal sectional view of the roll of FIG. 1, which is to be tested;

FIG. 3 is a sectional view taken in the direction of arrows along the line Y-Y of FIG. 2;

FIG. 4 is a sectional view of a main part of FIG. 2;

FIG. 5 is a transverse sectional view of another type of ring, which is different from that of FIG. 3;

FIG. 6 is a longitudinal sectional view of FIG. 5; and

FIG. 7 is a longitudinal sectional view of a conventional adiabatic roll.

DESCRIPTION OF REFERENCE NUMERALS FOR MAIN PARTS OF THE DRAWINGS

	1: metal tub shaft
	1A: through hole for passing cooling water therethrough
	1a: end
	1b: the other end
	1c: threaded part
	1d: metal tub shaft key groove
	2: heat-resistant ring
	2C: key groove
	5: fixed flange
	6: movable flange
	7: disk
	8: nut
	10: key
	6A: adiabatic roll
	2A: first heat-resistant ring part
	2B: second heat-resistant ring part
	2D: ring-shaped plate
	2E: round head screw

MODE FOR CARRYING OUT INVENTION

A description will now be provided for an adiabatic roll of the present invention with reference to the accompanying drawings. Furthermore, the same reference numerals are used throughout the different drawings to designate the same or similar components.

In FIG. 1, reference numeral 1 denotes a tub-shaped metal tub shaft which has a through hole 1A for guiding cooling water therethrough. A fixed flange 5 is welded into a circumference of an end 1a of the metal tub shaft 1, and a movable flange 6 is provided at the other end 1b thereof. The movable flange 6 is axially and elastically supported by a nut 8, which is screwed around an externally threaded part 1c of the other end 1b.

Disks 7 made of a predetermined material (for example, plural sheets of ring-shaped inorganic material which includes a non-asbestos containing ASK#2057 manufactured by ASK Technika Co. in Japan) and nickel•cobalt-based heat-resistant rings 2 are axially fitted around the metal tub shaft 1 between the flanges 5, 6. When the nut 8 is screwed to be moved toward to press the fixed flange 5, the disks 7 and the heat-resistant rings 2 are pressed and elastically and firmly supported, thereby creating an adiabatic roll 6A.

Furthermore, the heat-resistant rings 2 and the disks 7 are fitted around the metal tub shaft 1 without welding.

When the adiabatic roll 6A having a structure shown in FIG. 1 is subjected to a characteristic test, the roll may be as shown in FIGS. 2 to 4. However, with respect to the basic principle, all of the structures shown in FIGS. 1 to 4 constitute the same adiabatic roll 6A according to the present invention.

A pair of metal tub shaft key grooves 1d is formed with a 180° interval on an external wall of the metal tub shaft 1 shown in FIGS. 1 to 4 so that they are opposite to each other. A pair of key grooves 2C is formed on an internal wall of each heat-resistant ring 2, and keys 10 are inserted into spaces formed by the key grooves 1d, 2C. Accordingly, it is impossible to circumferentially rotate the heat-resistant rings 2 with respect to the metal tub shaft 1, but the rings can axially move.

In other words, the heat-resistant rings 2 are not axially fixed, but can axially move while they are interposed between the disks 7 made of inorganic material when thermal expansion and shrinkage occur.

Furthermore, a design is conducted so as to sufficiently compensate for circumferential thermal expansion and shrinkage, thus preventing idling of the heat-resistant rings 2 caused by impact applied in a rotational direction (circumferential direction) in the course of carrying a slab. In other words, if axial thermal expansion and shrinkage of the heat-resistant rings 2 occurs, the disks 7, which act as a spring prevent gaps from occurring and the heat-resistant rings 2 are not fixed. Accordingly, the generation of heat stress is reduced and it is possible to prevent separation.

With respect to heat loss of the water-cooled metal tub shaft 1 due to heat conduction of the heat-resistant rings 2, unlike a conventional structure in which the rings are welded into the metal tub shaft, the heat-resistant rings 2 are fitted around the water-cooled metal tub shift 1, thus providing resistance to heat transfer at interfaces of the rings and the shaft, thereby decreasing the amount of heat transferred.

A better understanding of the present invention may be obtained through the following examples, which are set forth to illustrate, but are not to be construed as the limit of the present invention.

EXAMPLE 1

An adiabatic roll (6A) having the size shown in FIGS. 2 to 4 was manufactured, and heated at 1200° C. in a siliconit furnace 11, indicated by a dotted line. Temperatures of portions of nickel•cobalt-based heat-resistant rings (xA to xD portions in FIGS. 3 and 4) were measured, and inlet and outlet temperatures of cooling water 20 were measured, so that the amount of heat loss was compared with that of a conventional welding structure or heat-resistant mortar adiabatic structure. Furthermore, whether gaps were formed at interfaces of the heat-resistant rings 2 and adiabatic material was visually confirmed.

In the conventional welding structure or heat-resistant mortar adiabatic structure, heat-resistant rings 2 were welded into a water-cooled metal tub shaft 1 in an adiabatic roll 6A shown in FIG. 7, and Y members 3 were welded into a portion of the metal tub shaft 1, at which disks 7 made of inorganic material were provided. Asahi light caster-13 (LC-13) manufactured by Asahi Glass Co., Ltd. was mixed therewith to produce a structure 4 which contained 35 wt % heat-resistant mortar and had an external diameter of 280, and comparison tests were conducted. The amount of cooling water used was 3 L/min.

EXAMPLE 2

The nickel•cobalt-based heat-resistant ring 2 was the same as described in example 1 except that it consisted of a first heat-resistant ring part 2A having a larger diameter and a second heat-resistant ring part 2B having a smaller diameter so that they were concentrically arranged on the same vertical axis as shown in FIGS. 5 and 6, and the second heat-resistant ring part 2B constituting the internal ring part was made of SUS310S. Furthermore, ring-shaped plates 2D and round head screws 2E were provided at a joint 2M so as to join the first and second heat-resistant ring parts 2A, 2B together. The remaining test conditions were the same as those of example 1.

EXAMPLE 3

The second heat-resistant ring part 2B, which constituted the internal ring part of the first and second heat-resistant ring parts 2A, 2B of example 2, was made of an Al₂O₃ ceramic sintered body instead of SUS310S. The remaining test conditions were the same as those of example 1.

EXAMPLE 4

The heat-resistant ring 2 of example 1 was made of an Al₂O₃ ceramic sintered body instead of nickel-cobalt-based heat-resistant steel. The remaining test conditions were the same as those of example 1.

The results of examples 1, 2, 3, and 4, and a comparative example are described in Table 1.

	TABLE 1
					Comparative
	Example 1	Example 2	Example 3	Example 4	Example

Temperature	Inlet	19	19	19	19	19
of cooling	Outlet	41	37	32	27	48
water ° C.
Temperatures	A	1165	1172	1185	1192	1149
of portions of	B	1070	1100	1150	1155	1055
heat-resistant	C	921	921	1100	950	843
ring ° C.	D	251	225	186	153	255

Heat loss amount of	3960	3240	2340	1440	5220
cooling water Kcal/Hr
Appearance of roll	No cracks	No cracks	No cracks	No cracks	Cracks and
after test	and no	and no	and no	and no	gaps (1.0-1.5 mm)
	gaps were	gaps were	gaps were	gaps were	were
	formed at	formed at	formed at	formed at	formed at the
	the	the	the	the	interface of the
	interface of	interface of	interface of	interface of	heat-resistant
	the heat-	the heat-	the heat-	the heat-	steel ring and
	resistant	resistant	resistant	resistant	the heat-
	ring and	ring and	ring and	ceramic	resistant mortar
	the	the	the	ring
	adiabatic	adiabatic	adiabatic	(Al2O3)
	disk	disk	disk	and the
				adiabatic
				disk