Insulating of furnace rolls

Abstract: An insulating roll is provided which is constructed with a roll body formed of a plurality of inorganic material-derived discs (6) laminated with each other and positioned axially of and around a metal conduit (1), and a heat-resistant metal tube (7) disposed integrally over an outer periphery of the roll body. The discs (6) do not consist of metal. A tubular cover formed by spray coating a ceramic material on the heat-resistant metal tube (7), or a sintered ceramics-made sleeve may be disposed, where desired, in place of the heat-resistant metal tube. This roll has low thermal conductivity and high impact strength without involving reduced surface temperature of a material being heat treated in a furnace, or reduced ambient temperature in the furnace during heat treatment.

Description: BACKGROUND OF THE INVENTION Technical Field of the Invention This invention relates to insulating rolls and has particular reference to an improved type of insulating roll which has low thermal conductivity and high impact strength without involving reduced surface temperature of materials being heat treated in a furnace (of materials being rolled), or reduced ambient temperature in the furnace during heat treatment. Description of the Related Art Certain rolls are generally known as insulating rolls, and they include a transport roll used in a process step of heat treatment wherein stainless steel tubes are welded with each other, a sealing roll used in a preheating step of steel in a reducing furnace so as to shield the ambient furnace gas at the inlet and outlet of the furnace, and a transport roll used in transporting a material to be treated in a furnace. EP 473926A discloses an insulating roll cover comprising compressed substantially ceramic fibre. EP 91292A discloses a ceramic coated roll. US 1,853,879 discloses a roll for sheet glass annealing leers. JP9-125157 discloses an insulating roll comprising a roll body having a water passage, through which cooling water is supplied from a longitudinal one end to a longitudinal other end of said roll body; a supplying source of cooling water for supplying cooling water to said roll body; an outer contact pipe coaxially mounted on said roll body at intervals radially outward from the outer periphery thereof; a heat insulating layer comprising powder and granular material having insulation, said layer lying between the inner periphery of said outer contact pipe and the outer periphery of said roll body; and a surface layer formed on the outer periphery of said outer contact pipe, said surface layer being made of heat resistant material endurable at least more than 700°C. SUMMARY OF THE INVENTION Accordingly, the present invention for its object provides an insulating roll which is capable of affording low thermal conductivity and high impact strength and is free of reduced surface temperature of materials beings heat treated in a furnace (of materials being rolled), or reduced ambient temperature in the furnace during heat treatment. According to one important aspect of the present invention, an insulating roll is provided which comprises: a roll body comprising a metal conduit 1 arranged to pass cooling water therethrough, and a thermally insulating material positioned axially of and around said metal conduit 1; and a metal tube 7 formed of a heat-resistant metal and fitted to cover said roll body; characterised in that said insulating material comprises a plurality of discs 6 formed of an inorganic material which does not consist of metal or asbestos; the metal tube 7 is mounted at one end 7a on a stepped portion 3aA provided in a fixed flange 3, and is securely attached to the stepped portion 3aA of the fixed flange 3, the fixed flange 3 being secured to one end 1a of the conduit 1 on its outer periphery; the metal tube 7 is mounted at the opposed end 7b on an outer periphery defined on a movable flange 4, and is capable of relatively moving on the movable flange 4, the movable flange 4 being movably mounted at the opposite end of the metal conduit 1, and being so structured as to be urged against nuts 5 interengaged with a screwed portion 1b of the metal conduit 1 and movable relative to both the conduit 1 and the tube 7 by rotating the nuts 5; and said discs 6 are tightly packed by means of the nuts 5 so as to fill a space defined between the conduit 1, the metal tube 7, the fixed flange 3 and the movable flange 4. Preferably, such roll further includes a tubular cover formed by spray coating of a ceramic material over the metal tube. Another aspect of the invention provides an insulating roll which comprises: a roll body comprising a metal conduit 1 arranged to pass cooling water therethrough, and a plurality of discs 6 formed of an inorganic material which does not consist of metal positioned axially on and around said metal conduit 1; and and a sleeve fitted to cover said roll body; characterised in that the sleeve is formed of sintered ceramic and is mounted at one end 7a on a stepped portion 3aA provided in a fixed flange 3, and is securely attached to the stepped portion 3aA of the fixed flange 3, the fixed flange 3 being secured to one end 1a of the conduit 1 on its outer periphery; and the sleeve is mounted at the opposed end 7b on an outer periphery defined on a movable flange 4, and is capable of relatively moving on the movable flange 4, the movable flange 4 being movably mounted at the opposite end of the metal conduit 1, and being so structured as to be urged against nuts 5 interengaged with a screwed portion 1b of the metal conduit 1 and movable relative to both the conduit 1 and the tube 7 by rotating the nuts 5; and further characterised in that said discs 6 are tightly packed by means of the nuts 5 so as to fill a space defined between the conduit 1, the metal tube 7, the fixed flange 3 and the movable flange 4. The discs are made of an inorganic material which does not consist of metal. Preferably, the inorganic material is a ceramic material or similar heat resistant material, such as ceramic fibre or rockwool. The above and other objects, features and advantages of the present invention will be readily apparent to those versed in the art from the following detailed description taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of one form of the insulating roll according to the present invention. FIG. 2 is a schematic diagram explanatory of a test apparatus used for the performance evaluation of the roll shown in FIG. 1. FIG. 3 is a schematic diagram explanatory of a test method used in determining the acoustic properties of the roll shown in FIG. 1. ILLUSTRATIVE EMBODIMENTS OF THE INVENTION Referring now to the drawings and to FIG. 1 in particular, a metal conduit designated at 1 is arranged to flow cooling water therethrough and is provided with guide paths 2. A fixed flange 3 is secured by welding to one end 1a of the conduit 1 on its outer periphery, and a movable flange 4 is located at the opposite end 1b of the conduit 1. The flange 4 is so structured as to be urged against nuts 5 interengaged with a screwed portion 1b. A plurality of ring-shaped inorganic material-derived discs 6 are laminated with each other and positioned axially of the roll and in a space defined between the metal conduit 1 and the fixed and movable flanges 3, 4. In this embodiment, the inorganic material-derived discs 6 are formed of a non-asbestos material which is made commercially available as tradenamed ASK #2055 from the assignee of the invention presented here. The non-asbestos material, however, should not be construed as limiting to the invention because other suitable inorganic materials may be employed where desired. When inwardly rotated, the nuts 5 are pressed toward the fixed flange 3 so that the discs 6 are brought into firmly pressed relation to each other. Lamination of the discs 6 on the conduit 1 leads to formation of a roll body 6A. A metal tube 7 made of a heat-resistant metal for example of SUS 310S is fitted to cover the roll body 6A between the fixed flange 3 and the movable flange 4. The metal tube 7 is mounted at its one end 7a on a stepped portion 3aA provided in the fixed flange 3 and at the opposed end 7b on an outer periphery 4a defined on the movable flange 4. The end 7a of the metal tube 7 is securely attached as by spot welding to the stepped portion 3aA, whereas the end 7b of the metal tube 7 is arranged to be in a non-stationary state, that is, capable of relatively moving on the movable flange 4. Due to the free movement of the end 7b even at high temperatures, the heat-resistant metal tube 7 can absorb structural changes tending to arise from heat shrinkage. Alternatively, a well-known sleeve (not shown) derived from a sintered ceramics may be used in place of the metal tube 7. It is desired that in the case of use of the heat-resistant metal tube 7, a tubular cover (not shown) be further disposed peripherally of such metal tube (namely sleeve), which tubular cover is obtainable by a known process for spray coating of a ceramic material. EXAMPLES Although the present invention has been generally described, a clear understanding of the invention can be obtained by reference to certain specific examples provided below. It should be noted that these examples are considered illustrative, but not restrictive. Example 1 Performance evaluation was made of an insulating roll viewed in FIG. 1. Testing was carried out with use of an apparatus shown in FIG. 2. Namely, the insulating roll 30 was positioned in a heating furnace 40, and a load roll 41 was located in adjoined relation to the roll 30. Cooling water 42 was allowed to flow through both of the rolls 30, 41, thereby putting the same in cooled condition. In this test, a heat-resistant metal tube 7 was made of SUS 310S, while inorganic material-derived discs 6 were formed from ASK #2055 manufactured by Astechnika Co. To facilitate comparison, a roll was produced and tested, though not shown, wherein a support ring with a thickness of 5 mm had been mounted centrally peripherally of a roll body so as to support a heat-resistant metal tube with respect to the roll body. Heating was effected by the heating furnace 40 of FIG. 2. Thermal insulation was adjudged by measurement of those temperatures read at an inlet and at an outlet of each of the two rolls 30, 41 at which places the cooling water 42 was introduced and discharged. Scale deposit was observed by causing the SUS 316-made load roll 41 to roll on the test roll 30. Test conditions were 1150°C in furnace temperature, 2.5 l/min in flow rate of cooling water, 78 N/cm [8kgf/cm] in linear pressure of load roll, 40 rpm in roll revolution and 24 hr in test time. Example 2 The same test conditions as in Example 1 were repeated except that a tubular cover was further disposed over the heat-resistant metal tube 7. This tubular cover was formed by spray coating of an Al 2 O 3 ·ZrO 2 ceramics in a thickness of 0.4 to 0.5 mm. Example 3 The same test conditions as in Example 1 were repeated except that a sleeve formed of an Al 2 O 3 ceramics manufactured by Nickerto Co. was used in place of the heat-resistant metal tube. Upon attachment of this sleeve to and over the metal conduit 1, the sleeve and the fixed flange 3 were fitted to each other with an inorganic adhesive of a thermally resistant type coated on their respective contacting surfaces. This was because the fixed flange 3 was not susceptible to welding. The beneficial effects obtained with Examples 1, 2 and 3 are tabulated in Table 1. Beneficial Effects of Example 1, 2 and 3 Example 1 Example 2 Example 3 Comparison Temperature of cooling water Inlet 18 18 18 18 °C Outlet 45 45 42 85 Flow rate of cooling 2.5 2.5 2.5 7.8 water, l/min Furnace temperature, °C 1150 1150 1150 860 Scale deposit Δ ○ ○ ○ Remarks Sufficient thermal insulation attained. ← ← Vapor lock avoided by increased flow rate of cooling water. Slight scale deposit Good Furnance temperature observed. resistance to ← not possibly scale deposit maintained at 1150°C obtained. due to too small capacity of furnance heater. Example 4 A comparative test was conducted with a transport roll of a commercial scale used for transporting a welded stainless steel tube to an annealing furnace. The transport roll currently practiced in the art is dimensioned to be 139.8mm in outside diameter of the outer tube, 9.5 mm in thickness of the outer tube and 2000 mm in face length of the roll and is formed from a SUS 310 material. Moreover, such transport roll is provided with a metal conduit 1 of a water-cooled type having an outside diameter of 60 mm, and support rings of 120.5 mm x 60 mm x 80 mm positioned at a pitch of 200 mm to thereby support the outer tube. After dismantling of those support rings from the roll, discs material which is derived by ASK #2055 which is made from Astechnika CO., Ltd. were located instead and fixed with a movable flange 4 and nuts 5. The outer tube was welded on a side where a fixed flange 3 was located, but was placed in a key-pin structure on a side where the movable flange 4 was located. This structure had a role to escape thermal expansion occurring axially of the outer tube, but absorb only torsional stress of the outer tube arising from rotation of the roll. An insulating roll 30 within the scope of the present invention and a conventional insulating roll as a comparative example were further tested by a method shown in FIG. 3. A steel ball 50 was allowed to drop on each of the rolls from a height of 650 mm at which time the resulting loudness of sound was collected by means of a vibration pickup 51. The beneficial effects obtained with Example 4 are tabulated in Table 2. Beneficial effects of Example 4 Example 4 Comparison (currently practiced) Temperature of cooling water Inlet 19 19 °C Outlet 53 78 Flow rate of cooling water, l/min. 10 80 Surface temperature of roll, °C 1075 795 Vibration level, dB 117 138 Being constructed as described and shown hereinbefore, the insulating roll of the present invention is conducive to significant advantages given below. In this roll construction, a heat-resistant metal tube, a tubular cover obtainable by spray coating a ceramic material on such metal tube, and a sleeve derivable from a sintered ceramics, all these members being arranged to constitute external parts of the roll, are excellent in thermal wear resistance and also in thermal shock resistance. Furthermore, the heat-resistant metal tube for use as an outer tube is highly resistant to warping due to deflection in the hot state since inorganic material-derived discs tightly packed are capable of supporting the outer tube in its entirety. The ceramics-spray coated cover or the sintered ceramics-made sleeve when used precludes surface defects such as scale deposition and the like which would take place on a material being heat treated, which defects cannot be fully prevented by use of the heat-resistant metal tube. This also avoids dents resulting from such defects and appearing on the heat-treated material, thus contributing greatly to improved yield of the treated material. Besides and advantageously, noise is abated which would be emitted upon collision of the roll with a material being transported.

Claims: An insulating roll comprising: a roll body comprising a metal conduit (1) arranged to pass cooling water therethrough, and a thermally insulating material positioned axially of and around said metal conduit (1); and a metal tube (7) formed of a heat-resistant metal and fitted to cover said roll body; characterised in that said insulating material comprises a plurality of discs (6) formed of an inorganic material which does not consist of metal or asbestos; the metal tube (7) is mounted at one end (7a) on a stepped portion (3aA) provided in a fixed flange (3), and is securely attached to the stepped portion (3aA) of the fixed flange (3), the fixed flange (3) being secured to one end 1a of the conduit (1) on its outer periphery; the metal tube (7) is mounted at the opposed end (7b) on an outer periphery defined on a movable flange (4), and is capable of relatively moving on the movable flange (4), the movable flange (4) being movably mounted at the opposite end of the metal conduit (1), and being so structured as to be urged against nuts (5) interengaged with a screwed portion (1b) of the metal conduit (1) and movable relative to both the conduit (1) and the tube (7) by rotating the nuts (5); and said discs (6) are tightly packed by means of the nuts (5) so as to fill a space defined between the conduit (1), the metal tube (7), the fixed flange (3) and the movable flange (4). An insulating roll according to claim 1, further including a tubular cover formed by spray coating of a ceramic material over said metal tube (7). An insulating roll comprising: a roll body comprising a metal conduit (1) arranged to pass cooling water therethrough, and a plurality of discs (6) formed of an inorganic material which does not consist of metal positioned axially on and around said metal conduit (1); and and a sleeve fitted to cover said roll body; characterised in that the sleeve is formed of sintered ceramic and is mounted at one end (7a) on a stepped portion (3aA) provided in a fixed flange (3), and is securely attached to the stepped portion (3aA) of the fixed flange (3), the fixed flange (3) being secured to one end (1a) of the conduit (1) on its outer periphery; and the sleeve is mounted at the opposed end (7b) on an outer periphery defined on a movable flange (4), and is capable of relatively moving on the movable flange (4), the movable flange (4) being movably mounted at the opposite end of the metal conduit (1), and being so structured as to be urged against nuts (5) interengaged with a screwed portion (1b) of the metal conduit (1) and movable relative to both the conduit (1) and the tube (7) by rotating the nuts (5); and further characterised in that said discs (6) are tightly packed by means of the nuts (5) so as to fill a space defined between the conduit (1), the metal tube (7), the fixed flange (3) and the movable flange (4).

Inventors: HIRAGURI KANJI, YOKOMIZO TOMOAKI, HIRAGURI, KANJI, YOKOMIZO, TOMOAKI, Hiraguri, Kanji, c/o Ask Technica Corporation, Yokomizo, Tomoaki, c/o Ask Technica Corporation
Applicants: ASK TECHNICA CORP, ASK TECHNICA CORPORATION
Application year: 1998
Main classification: F27D3
IPC codes: C21D1, C21D9, C03B35, F27D3