CA1079099A - Method for producing a steel strip by hot rolling - Google Patents
Method for producing a steel strip by hot rollingInfo
- Publication number
- CA1079099A CA1079099A CA286,896A CA286896A CA1079099A CA 1079099 A CA1079099 A CA 1079099A CA 286896 A CA286896 A CA 286896A CA 1079099 A CA1079099 A CA 1079099A
- Authority
- CA
- Canada
- Prior art keywords
- hot
- overlapped portions
- rolling
- steel band
- steel
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B15/00—Arrangements for performing additional metal-working operations specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
- B21B15/0085—Joining ends of material to continuous strip, bar or sheet
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
- B21B1/22—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling plates, strips, bands or sheets of indefinite length
- B21B1/24—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling plates, strips, bands or sheets of indefinite length in a continuous or semi-continuous process
- B21B1/26—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling plates, strips, bands or sheets of indefinite length in a continuous or semi-continuous process by hot-rolling, e.g. Steckel hot mill
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B2261/00—Product parameters
- B21B2261/02—Transverse dimensions
- B21B2261/04—Thickness, gauge
- B21B2261/05—Different constant thicknesses in one rolled product
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Metal Rolling (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
In a method for producing a hot strip by hot rough roll-ing, a steel slab heated to a rolling temperature to obtain a steel band, and hot finishing rolling the steel band in a continuous man-ner, the improvements comprising overlapping a forward end portion of a steel band which is being rolled by the rough hot rolling o-ver a finishing end portion of a similarly rolled preceding steel band before or during the hot finishing rolling step, with inser-tion between the overlapped portions of the both hot bands of an oxide scale-fusing agent which reacts with the oxide scale present on the opposing surfaces of the overlapped portions by the heat of the overlapped portions and forms a low-melting point substance, fixing temporarily the overlapped portions by means of a metallic nail-like member driven into the overlapped portions if necessary, bonding the overlapped portions by reduction, and subjecting the steel bands thus bonded to the hot finishing rolling continuously.
In a method for producing a hot strip by hot rough roll-ing, a steel slab heated to a rolling temperature to obtain a steel band, and hot finishing rolling the steel band in a continuous man-ner, the improvements comprising overlapping a forward end portion of a steel band which is being rolled by the rough hot rolling o-ver a finishing end portion of a similarly rolled preceding steel band before or during the hot finishing rolling step, with inser-tion between the overlapped portions of the both hot bands of an oxide scale-fusing agent which reacts with the oxide scale present on the opposing surfaces of the overlapped portions by the heat of the overlapped portions and forms a low-melting point substance, fixing temporarily the overlapped portions by means of a metallic nail-like member driven into the overlapped portions if necessary, bonding the overlapped portions by reduction, and subjecting the steel bands thus bonded to the hot finishing rolling continuously.
Description
1~'79()99 The present invention relates to a method for produc-ing a steel strip by hot rolling in a continuous way.
For producing a hot strip coil from a stell slab, the steel slab is subjected to surface defect detection, and removed of the surface defects by hot scarfing, etc. The steel slab thus surface-conditioned ls heated in a reheating furnace, then subject-ed to rough rolling, intermediate rolling in some cases, finishing rolling, cooling on a run-out table, and is coiled on a coiler.
The rolling is intermittently slab by slab. In this case, the forward end of the hot strip coming out of the last stand of the finishing rolling train is normally maintained in a running speed of 1600 to 1800 f.p.m. from while it runs on the run-out table. -When the forward end of the hot strip runs on the run-out table at - a higher speed, it leaps vigorously, often causing flying. When the forward end of the hot strip is coiled on the coiler, the run-ning speed of the hot strip is increased up to the speed designated by the mill operation or determined by a specific hot strip produc-tion line.
In this way, in case of an intermittent rolling proce-dure in which the rolling is done slab by slab, it is necessary tomaintain the running speed of the hot strip while the forward end of the hot strip comes out and reaches the coiler, and the produc-tivity of the hot strip mill is low because and idle time of ope-ration exists between the completion of rolling of a preceding slab and the starting of rolling a subsequent slab.
Further, the temperature of the hot strip lowers consi-derably before the forward end of the hot strip reaches the coiler, because the running speed of the hot strip is maintained at a remar-kably low speed while it comes out of the finishing rolling mill 3Q train and reaches the coiler as mentioned above.
In case of rolling a hot strip, however, it is requir-ed that the temperature of the hot strip at the exit side of the - ::
-1~79099 finishing rolling mill train is within a certain zone in order tomaintain a required quality of the hot strip, and for this requi-rement, the temperature at which the steel slab is extracted from a slab heating furnace must be maintained higher so as to compen-sate the temperature lowering mentioned before. This is the rea-son why the heat unit can not be lowered in the hot strip rolling.
m irdly it is required that the hot strip from its for-ward end to the finishing end is subjected to a uniform heat his-tory in order to control the quality, but as mentioned before, the running s'peed of the hot strip must be maintained at a remarkably low speed while the forward end comes out of the finishing rolling mill train and reaches the coiler, so that it is almost impossible to avoid the irregularity of the heat history in the length direc-tion of the hot strip.
Fourthly, the forward end and the finishing end of the hot strip must be cut off, because they are in the tongue-like or fish tail-like shape, thus lowering the production yield.
In order to perform the hot rolling continuously, it has been proposed to bond successively the steel materials to be rolled. According to this method, the end portion of a preceding steel material being rolled is overlapped with the forward end portion of a subsequent steel material being rolled, and the roll-ing is done on the overlapped portions to bond the preceding and subsequent steel materials, and thus bonded materials are supplied to the finishing hot rolling step to perform the hot rolling con-tinuously. In this method, however, it is necessary that both sldes of the overlapped portions are temporarily welded, that the thicX-ness of scales on both inside opposing surfaces of the overlapped -portions is maintained 40 ~u or less, that the length in the rolling direction of the overlapped portions is at least 1/2 of the width of the steelmaterial being rolled~, and thatthe overlappedportions are ' ~ -2-1C~79099 rolled with a reduction percentage 30 % or higher at the initial stage of the finishing rolling step.
Therefore, the method according to the above Japanese Laid-Open Patent Specification has disadvantages that a welding machine is required for performing the temporary welding of the both sides of the overlapped portions while the material running, that the production yield is low because of the necessity to over-lap the materials over a length of at least 1/2 of the width of the material, and that a rolling equipment of large capacity is required because at least 30 % reduction is done on the overlapped portions at the initial rolling of the subsequent material in the finishing rolling mill train.
The object of the present invention is to provide a production method of hot strip by continuous hot rolling which eli-minates completely the above problems and disadvantageous confront-ed with by the conventional methods and can be carried out advan-tageously on a commercial scale.
The above object of the present invention is achieved by the following features that in a method in which a steel slab heated to its rolling temperature is subjected to a rough hot rol-ling, an intermediate hot rolling lf necessary and a finishing hot rolling to obtain a hot strip, a forward end portion of a steel band rolled by the hot rough rolling and, if necessary, subsequen-tly by the intermediate hot rolling is overlapped with a finishing end portion of a preceding steel band similarly rolled before or during the hot finishing rolling step, with insertion between the overlapped portions of the both hot bands of an oxide scale-fusing agent which reacts with the oxide scale present on the opposing surfaces of the overlappe~ portions by the heat of the overlapped portions and forms a low melting point substance having high flowability, at least one metallic nail-like member is driven into the overlapped portions to temporarlly fixed the overlappeJ portions ' ~ .
1079~99 if necessary and the overlapped portions are bonded by rolling re-duction and subjected to the hot finishing rolling to obtain a steel hot strip continuously.
For the continuous production of the hot strip by the hot rough rolling step, the intermediate rolling step, if necessary, and the hot finishing rolling step, the steel slabs may be bonded one after another before the hot rough rolling or the steel bands after the rough rolling are bonded between the rough rolling step and the finishing rolling step, or in same cases between the inter-mediate rolling step and the finishing rolling step or the roughrolling step.
However, when the steel slabs are bonded before the hot rough rolling step, the rough rolling step and the finishing rolling step must be associated, but such association through the whole mill stands is difficult to achieve by the present rolling technics, and as the steel slabs have a relatively large thickness the jointed (overlapped) portion after the finishing rolling step occupies a considerable length in the final hot strip which must be cut off, thus resulting in considerable lowering of the production yield.
Whereas, when the steel bands after the rough rolling step are bonded as above, the disadvantages by the slab bonding can be eliminated.
Therefore, the present invention is limited to the bonding of the steel bands after the rough rolling step and thus according to the present invention, the forward end portion of a steel band obtained by the hot rough rolling, or in some cases fur-ther by the intermediate rolling is overlapped and bonded with the finishing end portion of a preceding steel band before or during the finishing rolling step.
The bonding, however, must be performed with the fol-lowlng considerations that the bonded portions are not adverse to the rolling condition and the bonding is done in a very short period of time, and the bond strength must stand for at least the rolling under tension in the finishing rolling step.
For the above considerations, the finishing end por-tion of the preceding steel hot band is overlapped with the forward end portion of the subsequent steel hot band and the overlapped portions are bonded together by pressure in the present invention.
As mentioned just above, the strength of the portions bonded by pressure must be enough to stand for the rolling under tension of the steel hot band in the finishing rolling step. The pressure bond-ing can be achieved by contact bond of the opposing surfaces of the base metals of the overlapped portions of the hot bands. However, the oxide scale present on the surface of the steel band hinders the bonding by pressure of the base metals, and thus the oxide sca-le must be removed before the bonding.The oxide scale may be remo-v~ed by a mechanical grinding such as brushing or by a gas grinding such as ~ hot scarfing using the oxygen gas, but it is extremely dif-ficult to remove the oxide scale from the running steel band i~ a short time by the above means, and if removed, a new oxide scale is formed soon on the steel band surface and this newly formed oxide scale hinders the bonding.
According to the present invention, for removal of the oxide scale present on the surfaces of the finishing end portion of a preceding steel band and on the surface of the forward end portion of a subse~uent steel band, a scale-fusing agent which reacts to the oxide scale at the temperature of the steel bands to be bonded and forms a low melting point substance having high flowability is in-serted betweeen the overlapped end portions to be bonded by the rol-ling and is squeezed out. Together with the low melting point sub-stace being squezed out, the oxide scale is substantially removedfrom the band surfaces of the overlapped end portions so that sa-tisfactory bonding of the opposing metal surfaces can be obtained.
The temperature of the steel bands at the time of their bonding by pressure is advantageously not less than 1000C and as the steel band is supplied to the hot finishing rolling mill train normally at a temperature between about 1000 and 1050C, a desirable pressu-re bonding temperature can be maintained without any specific consi-deration so far as the rolling is done under the ordinary hot rol-ling conditions.
As the scale-fusing agent used in the present invention, one or~more i5 selected from the group consisting of oxides, complex oxides, chlorides, sulfates, nitrates, carbonates and phosphates in the powder form of Li, Na, K, Mg, Ca, Ba, B, Al, Si, Pb, P and Fe which reacts with the oxide scale with the heat (not lower than 1000C) contained in the hot steel bands to w'nich the agent is appli-ed and forms a low melting point substance having high flowability.
For the application of the scale fusing agent to the surfaces of the hot steel bands to be bonded together, in case of the oxides or complex oxides, for example boron oxides or complex oxides, they may be applied directly in the form of B203.for exam-ple, or they may be applied in the form of boric acid ( H2B03) which is dehydrated immediately into the boron oxide because the hot band is at high temperatures not lower than 1000C so that the same re-sult can be obtained as the boron oxide (B2O3) is applied. Therefo-re, in the present invention the oxides or complex oxides include substances which decompose at a temperature not lower that 1000C
to produce an oxide.
As described above, the scale-fusing agent is applied to the opposing surfaces of the overlapped portions of the hot steel bands and the overlapped portions are bonded by the rolling and the - oxide scale which has been converted into the low melting point substance is squeezed out so that a satisfactory bondage between the opposing metal surfaces is obtained. However, in order to as-sure the bondage, it is desirable to avoid the slipping of the op-- -posing surfaces in the overlapped portions before the completion of the bondage, and it is also desirable to avoid the increase in the width and warping of the overlapped portions during the rolling.
In this way, a satisfactory bondage can be obtained.
The slipping between the opposing surfaces of the over-lapped portions, and the width increase and warping of the over-lapped portions during the rolling can be avoided by temporarily fixing the overlapped portions mechanically, and as the mechanical temporary fixing means according to the present invention, at least one nail-like member made of carbon steel or low ally steel, for example, is driven through the overlapped portions to temporarily fixed them. This can be done easily in a very short period of time during the running of the steel bands. As t~e means for drivin~
the nail-like member through the overlapped portions, in may be do-ne by one or more known nail driving gun of explosion, high pressu-re gas or compressed air type.
The nail-like member is required to have a strength higher than that required for driving through the overlapped por-tions at the high temperature, but when the strength of nail-like member is excessively high, it damages the roll surace during the subsequent rolling and thus an excessively high strength of the nail-like member should be avoided. Preferably, nail-like members should be selected which have such a character that the strength lowers as they receive heat from the steel band and becomes almost equal to the strength of the steel band during the subsequent rolling.
The number of the nail-lide members to be driven per unit surface area of the overlapped portions should be limited to the minimum required for maintaining the stability of the rolling of the overlapped portions. An excessive number of the nail-lide members driven through the overlapped portions will lower the strength of the overlapped portions, often resulting in rupture thereof dur-ing the subsequent Folling .
The present invention will be more clearly understood from the following description of preferred embodiments with refe-rence to the attached drawings.
Fig. 1 shows on example of the apparatuses used for carrying out the method according to the present invention.
Fig. 2 shows the overlapped portions of the steel bands temporarily fixed by the nail-like members.
Fig. 3(a)(b)(c) show respectively the modes of during the nail-like members into the overlapped portions.
In Fig. 1, 1 represents the last stand of a hot rough rolling mill train. A hot band 2 prepared by rolling a soaked steel slab in the hot rough rolling mill train comes out of the last stand l of the said mill train and advances on the roller of the delay table in the direction of the arrow (a) to direct to the first stand 9 of a hot finishing rolling mill train. The delay table arranged between the last stand 1 and the first sta~d 9 is .: -composed of a fixed delay table 10 having rollers 12, a tilting delay table 10' having rollers 12' and a fixed delay table 10"
having rollers 12". m e tilting delay table 10' is so structured as to shift from its horizontal position to its tilted position as the piston rod 13 of the hydraulic unit 11 provided at the forward end rises.
In Fig. 1, a part of the preceding hot band 3 which has been rough hot rolled is already introduced in the finishing hot rolling mill train, while the tail end of the hot band 3 is on the roller 12 of the delay table 10 at the inlet side of the hot rolling mill train, and the lead end of the subsequent rough hot rolled hot band 2 is overlapped on the tail end of the hot band 3 .
The tail end of the preceding hot band 3 is detected by the hot metal detector 4 (infrared measuring meter) when it has passed the hot metal detector 4 . The detection signal is ~079099 sent to the spraying device 5 which stores and sprays the oxide scale fusing agent, and this spraying device 5 starts to operate immediately when it receives the signal from the hot metal detec-tor 4 that the tail end of the hot band 3 has passed the hot metal detector 4 and sprays the oxide scale fusing agent on the tail end of the hot band 3 for a predetermined period of time.
When the hot metal detector 4 detects the tail end of the hot band 3 , the detection signal is simultaneously sent to the operation circuit of a solenoid valve 11' , which actuates a hydraulic unit 11 for tilting the delay table 10' .
When the operation circuit rçceives the signal from the hot metal detector, the hydraulic unit 11 operates to tilt the delay table 10' . The detection signal emitted when the hot metal detector 4 detects the tail end of the hot band 3 is sent to a rotation control deyice (not shown) for controlling the rotation speed of the rollers 12' and 12 of the delay table.
When the rotation control device receives the signal from the hot metal detector 4 , the rotation speed of the rollers 12' and 12 is increased to increase the running speed of the subsequent hot band 2 .
In this way, the lead end of the hot band 2 overlaps over the tail end of the hot band 3 on which the oxide scale fusing agent has been sprayed.
Meanwhile, before the hot metal detector 4 detects the tail end of the hot band 3 , the rotation speed of the roll-ers 12 , 12' and 12" of the delay table 10 , 10' and 10"
is controlled so as to cause the preceding hot band 3 and the ., subsequent hot band 2 run at a constant distance and at the same speed.
As the hydraulic lifting rod 13 rises, the delay table 10' shifts from its horizontal position to its tilted position as ~,J _9_ shown, and on the other hand, as the running speed of the hot band
For producing a hot strip coil from a stell slab, the steel slab is subjected to surface defect detection, and removed of the surface defects by hot scarfing, etc. The steel slab thus surface-conditioned ls heated in a reheating furnace, then subject-ed to rough rolling, intermediate rolling in some cases, finishing rolling, cooling on a run-out table, and is coiled on a coiler.
The rolling is intermittently slab by slab. In this case, the forward end of the hot strip coming out of the last stand of the finishing rolling train is normally maintained in a running speed of 1600 to 1800 f.p.m. from while it runs on the run-out table. -When the forward end of the hot strip runs on the run-out table at - a higher speed, it leaps vigorously, often causing flying. When the forward end of the hot strip is coiled on the coiler, the run-ning speed of the hot strip is increased up to the speed designated by the mill operation or determined by a specific hot strip produc-tion line.
In this way, in case of an intermittent rolling proce-dure in which the rolling is done slab by slab, it is necessary tomaintain the running speed of the hot strip while the forward end of the hot strip comes out and reaches the coiler, and the produc-tivity of the hot strip mill is low because and idle time of ope-ration exists between the completion of rolling of a preceding slab and the starting of rolling a subsequent slab.
Further, the temperature of the hot strip lowers consi-derably before the forward end of the hot strip reaches the coiler, because the running speed of the hot strip is maintained at a remar-kably low speed while it comes out of the finishing rolling mill 3Q train and reaches the coiler as mentioned above.
In case of rolling a hot strip, however, it is requir-ed that the temperature of the hot strip at the exit side of the - ::
-1~79099 finishing rolling mill train is within a certain zone in order tomaintain a required quality of the hot strip, and for this requi-rement, the temperature at which the steel slab is extracted from a slab heating furnace must be maintained higher so as to compen-sate the temperature lowering mentioned before. This is the rea-son why the heat unit can not be lowered in the hot strip rolling.
m irdly it is required that the hot strip from its for-ward end to the finishing end is subjected to a uniform heat his-tory in order to control the quality, but as mentioned before, the running s'peed of the hot strip must be maintained at a remarkably low speed while the forward end comes out of the finishing rolling mill train and reaches the coiler, so that it is almost impossible to avoid the irregularity of the heat history in the length direc-tion of the hot strip.
Fourthly, the forward end and the finishing end of the hot strip must be cut off, because they are in the tongue-like or fish tail-like shape, thus lowering the production yield.
In order to perform the hot rolling continuously, it has been proposed to bond successively the steel materials to be rolled. According to this method, the end portion of a preceding steel material being rolled is overlapped with the forward end portion of a subsequent steel material being rolled, and the roll-ing is done on the overlapped portions to bond the preceding and subsequent steel materials, and thus bonded materials are supplied to the finishing hot rolling step to perform the hot rolling con-tinuously. In this method, however, it is necessary that both sldes of the overlapped portions are temporarily welded, that the thicX-ness of scales on both inside opposing surfaces of the overlapped -portions is maintained 40 ~u or less, that the length in the rolling direction of the overlapped portions is at least 1/2 of the width of the steelmaterial being rolled~, and thatthe overlappedportions are ' ~ -2-1C~79099 rolled with a reduction percentage 30 % or higher at the initial stage of the finishing rolling step.
Therefore, the method according to the above Japanese Laid-Open Patent Specification has disadvantages that a welding machine is required for performing the temporary welding of the both sides of the overlapped portions while the material running, that the production yield is low because of the necessity to over-lap the materials over a length of at least 1/2 of the width of the material, and that a rolling equipment of large capacity is required because at least 30 % reduction is done on the overlapped portions at the initial rolling of the subsequent material in the finishing rolling mill train.
The object of the present invention is to provide a production method of hot strip by continuous hot rolling which eli-minates completely the above problems and disadvantageous confront-ed with by the conventional methods and can be carried out advan-tageously on a commercial scale.
The above object of the present invention is achieved by the following features that in a method in which a steel slab heated to its rolling temperature is subjected to a rough hot rol-ling, an intermediate hot rolling lf necessary and a finishing hot rolling to obtain a hot strip, a forward end portion of a steel band rolled by the hot rough rolling and, if necessary, subsequen-tly by the intermediate hot rolling is overlapped with a finishing end portion of a preceding steel band similarly rolled before or during the hot finishing rolling step, with insertion between the overlapped portions of the both hot bands of an oxide scale-fusing agent which reacts with the oxide scale present on the opposing surfaces of the overlappe~ portions by the heat of the overlapped portions and forms a low melting point substance having high flowability, at least one metallic nail-like member is driven into the overlapped portions to temporarlly fixed the overlappeJ portions ' ~ .
1079~99 if necessary and the overlapped portions are bonded by rolling re-duction and subjected to the hot finishing rolling to obtain a steel hot strip continuously.
For the continuous production of the hot strip by the hot rough rolling step, the intermediate rolling step, if necessary, and the hot finishing rolling step, the steel slabs may be bonded one after another before the hot rough rolling or the steel bands after the rough rolling are bonded between the rough rolling step and the finishing rolling step, or in same cases between the inter-mediate rolling step and the finishing rolling step or the roughrolling step.
However, when the steel slabs are bonded before the hot rough rolling step, the rough rolling step and the finishing rolling step must be associated, but such association through the whole mill stands is difficult to achieve by the present rolling technics, and as the steel slabs have a relatively large thickness the jointed (overlapped) portion after the finishing rolling step occupies a considerable length in the final hot strip which must be cut off, thus resulting in considerable lowering of the production yield.
Whereas, when the steel bands after the rough rolling step are bonded as above, the disadvantages by the slab bonding can be eliminated.
Therefore, the present invention is limited to the bonding of the steel bands after the rough rolling step and thus according to the present invention, the forward end portion of a steel band obtained by the hot rough rolling, or in some cases fur-ther by the intermediate rolling is overlapped and bonded with the finishing end portion of a preceding steel band before or during the finishing rolling step.
The bonding, however, must be performed with the fol-lowlng considerations that the bonded portions are not adverse to the rolling condition and the bonding is done in a very short period of time, and the bond strength must stand for at least the rolling under tension in the finishing rolling step.
For the above considerations, the finishing end por-tion of the preceding steel hot band is overlapped with the forward end portion of the subsequent steel hot band and the overlapped portions are bonded together by pressure in the present invention.
As mentioned just above, the strength of the portions bonded by pressure must be enough to stand for the rolling under tension of the steel hot band in the finishing rolling step. The pressure bond-ing can be achieved by contact bond of the opposing surfaces of the base metals of the overlapped portions of the hot bands. However, the oxide scale present on the surface of the steel band hinders the bonding by pressure of the base metals, and thus the oxide sca-le must be removed before the bonding.The oxide scale may be remo-v~ed by a mechanical grinding such as brushing or by a gas grinding such as ~ hot scarfing using the oxygen gas, but it is extremely dif-ficult to remove the oxide scale from the running steel band i~ a short time by the above means, and if removed, a new oxide scale is formed soon on the steel band surface and this newly formed oxide scale hinders the bonding.
According to the present invention, for removal of the oxide scale present on the surfaces of the finishing end portion of a preceding steel band and on the surface of the forward end portion of a subse~uent steel band, a scale-fusing agent which reacts to the oxide scale at the temperature of the steel bands to be bonded and forms a low melting point substance having high flowability is in-serted betweeen the overlapped end portions to be bonded by the rol-ling and is squeezed out. Together with the low melting point sub-stace being squezed out, the oxide scale is substantially removedfrom the band surfaces of the overlapped end portions so that sa-tisfactory bonding of the opposing metal surfaces can be obtained.
The temperature of the steel bands at the time of their bonding by pressure is advantageously not less than 1000C and as the steel band is supplied to the hot finishing rolling mill train normally at a temperature between about 1000 and 1050C, a desirable pressu-re bonding temperature can be maintained without any specific consi-deration so far as the rolling is done under the ordinary hot rol-ling conditions.
As the scale-fusing agent used in the present invention, one or~more i5 selected from the group consisting of oxides, complex oxides, chlorides, sulfates, nitrates, carbonates and phosphates in the powder form of Li, Na, K, Mg, Ca, Ba, B, Al, Si, Pb, P and Fe which reacts with the oxide scale with the heat (not lower than 1000C) contained in the hot steel bands to w'nich the agent is appli-ed and forms a low melting point substance having high flowability.
For the application of the scale fusing agent to the surfaces of the hot steel bands to be bonded together, in case of the oxides or complex oxides, for example boron oxides or complex oxides, they may be applied directly in the form of B203.for exam-ple, or they may be applied in the form of boric acid ( H2B03) which is dehydrated immediately into the boron oxide because the hot band is at high temperatures not lower than 1000C so that the same re-sult can be obtained as the boron oxide (B2O3) is applied. Therefo-re, in the present invention the oxides or complex oxides include substances which decompose at a temperature not lower that 1000C
to produce an oxide.
As described above, the scale-fusing agent is applied to the opposing surfaces of the overlapped portions of the hot steel bands and the overlapped portions are bonded by the rolling and the - oxide scale which has been converted into the low melting point substance is squeezed out so that a satisfactory bondage between the opposing metal surfaces is obtained. However, in order to as-sure the bondage, it is desirable to avoid the slipping of the op-- -posing surfaces in the overlapped portions before the completion of the bondage, and it is also desirable to avoid the increase in the width and warping of the overlapped portions during the rolling.
In this way, a satisfactory bondage can be obtained.
The slipping between the opposing surfaces of the over-lapped portions, and the width increase and warping of the over-lapped portions during the rolling can be avoided by temporarily fixing the overlapped portions mechanically, and as the mechanical temporary fixing means according to the present invention, at least one nail-like member made of carbon steel or low ally steel, for example, is driven through the overlapped portions to temporarily fixed them. This can be done easily in a very short period of time during the running of the steel bands. As t~e means for drivin~
the nail-like member through the overlapped portions, in may be do-ne by one or more known nail driving gun of explosion, high pressu-re gas or compressed air type.
The nail-like member is required to have a strength higher than that required for driving through the overlapped por-tions at the high temperature, but when the strength of nail-like member is excessively high, it damages the roll surace during the subsequent rolling and thus an excessively high strength of the nail-like member should be avoided. Preferably, nail-like members should be selected which have such a character that the strength lowers as they receive heat from the steel band and becomes almost equal to the strength of the steel band during the subsequent rolling.
The number of the nail-lide members to be driven per unit surface area of the overlapped portions should be limited to the minimum required for maintaining the stability of the rolling of the overlapped portions. An excessive number of the nail-lide members driven through the overlapped portions will lower the strength of the overlapped portions, often resulting in rupture thereof dur-ing the subsequent Folling .
The present invention will be more clearly understood from the following description of preferred embodiments with refe-rence to the attached drawings.
Fig. 1 shows on example of the apparatuses used for carrying out the method according to the present invention.
Fig. 2 shows the overlapped portions of the steel bands temporarily fixed by the nail-like members.
Fig. 3(a)(b)(c) show respectively the modes of during the nail-like members into the overlapped portions.
In Fig. 1, 1 represents the last stand of a hot rough rolling mill train. A hot band 2 prepared by rolling a soaked steel slab in the hot rough rolling mill train comes out of the last stand l of the said mill train and advances on the roller of the delay table in the direction of the arrow (a) to direct to the first stand 9 of a hot finishing rolling mill train. The delay table arranged between the last stand 1 and the first sta~d 9 is .: -composed of a fixed delay table 10 having rollers 12, a tilting delay table 10' having rollers 12' and a fixed delay table 10"
having rollers 12". m e tilting delay table 10' is so structured as to shift from its horizontal position to its tilted position as the piston rod 13 of the hydraulic unit 11 provided at the forward end rises.
In Fig. 1, a part of the preceding hot band 3 which has been rough hot rolled is already introduced in the finishing hot rolling mill train, while the tail end of the hot band 3 is on the roller 12 of the delay table 10 at the inlet side of the hot rolling mill train, and the lead end of the subsequent rough hot rolled hot band 2 is overlapped on the tail end of the hot band 3 .
The tail end of the preceding hot band 3 is detected by the hot metal detector 4 (infrared measuring meter) when it has passed the hot metal detector 4 . The detection signal is ~079099 sent to the spraying device 5 which stores and sprays the oxide scale fusing agent, and this spraying device 5 starts to operate immediately when it receives the signal from the hot metal detec-tor 4 that the tail end of the hot band 3 has passed the hot metal detector 4 and sprays the oxide scale fusing agent on the tail end of the hot band 3 for a predetermined period of time.
When the hot metal detector 4 detects the tail end of the hot band 3 , the detection signal is simultaneously sent to the operation circuit of a solenoid valve 11' , which actuates a hydraulic unit 11 for tilting the delay table 10' .
When the operation circuit rçceives the signal from the hot metal detector, the hydraulic unit 11 operates to tilt the delay table 10' . The detection signal emitted when the hot metal detector 4 detects the tail end of the hot band 3 is sent to a rotation control deyice (not shown) for controlling the rotation speed of the rollers 12' and 12 of the delay table.
When the rotation control device receives the signal from the hot metal detector 4 , the rotation speed of the rollers 12' and 12 is increased to increase the running speed of the subsequent hot band 2 .
In this way, the lead end of the hot band 2 overlaps over the tail end of the hot band 3 on which the oxide scale fusing agent has been sprayed.
Meanwhile, before the hot metal detector 4 detects the tail end of the hot band 3 , the rotation speed of the roll-ers 12 , 12' and 12" of the delay table 10 , 10' and 10"
is controlled so as to cause the preceding hot band 3 and the ., subsequent hot band 2 run at a constant distance and at the same speed.
As the hydraulic lifting rod 13 rises, the delay table 10' shifts from its horizontal position to its tilted position as ~,J _9_ shown, and on the other hand, as the running speed of the hot band
2 is increased over that of the hot band 3 so that the forward end portion of the hot band 2 begins to overlap over the finishing end portion of the preceding hot band 3.
At a forward position in the advancing direction of the hot bands, there is positioned another X-ray measuring meter 6 above the hot band 3. When the forward edge of the hot band 2 is detected by the X-ray measuring meter 6 while it is r-unning and overlapping over the finishing end portion of the hot band 3, the lifting rod 13 of the hydraulic unit 11 is caused to get down to restore the delay table 10' to its original hoxizontal state, and at the same time the rotation control device of the rollers 12, 12' of the delay table 10, 10' is actuated to synchronize the running speed of the hot band 3 with that of the hot band 2. In this way the overlapping of the end portions of both bands is completed.
The overlapped portions run on the rollers 12" of the delay table 10" and are introduced into the first stand 9 of the , hot finishing rolling mill train, where the overlapped portions are bonded by the rolling reduction. During the rolling reduction, the oxide scale on the opposing surfaces of the overlapped portions :
, is squeezed out because it has been already,converted into the low melting point and fluid substance by reaction with the oxide scale-fusing agent, so that the base metal of the opposing surfaces is substantially exposed thereby and a metal-to-metal bonding is ob- ' ; tained'.' The bonding may be performed by a pressing means such as a rotary press (not shown) before the overlapped portions enter -the first stand 9.
The hot bands thus bonded are~cont'inuously finish-rolled in'the.hot finishing rolling mill train.
During the bonding of the overlapped portions by the rolling or the pressing, it someti~es occurs that the overlapped portions deviate from each other, increase in width, or warp.
~ f_10_ .. . . . . ...
-` ~079~99 Therefore, it is desirable that the overlapped portions are temporarily fixed as described below and then rolled or pressed to bond them.
As shown in Fig. 1, the hammering device 7 and the X-ray measuring meter 8 are arranged closer to the finishing rolling mill train than the X-ray measuring meter 6 . The X-ray measuring meter 8 detects the overlapped portion, namely, the lead end of the hot band 2 on which the tail end of the hot band 3 overlaps.
When the X-ray measuring meter 8 detects the lead head of the hot band 2 the detection signal is sent to the hammering device 7 , so that the hammering device 7 is actuated to drive the nail-like members successively into the overlapped portions of the tail end of the hot band 3 and the lead end of the hot band 2 . In this way, the overlapped portions of the tail end of the hot band 3 and the léad end of the hot band 2 are temporarily fixed. Then the temporarily fixed overlapped portions are introduced into the first stand 9 of the hot finish rolling mill train where the overlapped portions are bonded by the roll-ing reduction and then the hot bands thus bonded are continu-, , ously ! subjected;to the finishing rolling by the first and ,~
~' ' - :`
. ~; ' ' .
. . .
.
.
` ~ ' - ' : :
. . . ~. - .: .- .
107909g subsequent stands of the hot finishing rolling mill train.
The driving of the nail-like members 14 into the over-lapped portions may be done in such a manner as they penetrate just across the hot bands 2 and 3 as shown in Fig. 2 or in such a manner as they penetrate the hot bands 2 and 3 with both end projecting out the both surfaces, or penetrate partially across the overlapped por-tions as shown in Fig. 3(a) to (c).
In the above embodiment, the preceding and subsequent hot bands are bonded between the last stand of the hot rough rolling mill train and the first stand of the hot finishing rolling mill train to continuously produce the hot strip. However, without deviating from the scope and spirit of the present invention, the last stand 1 of the hot rough rolling mill train may be replaced by the first stand of the hot finishing rolling mill train, and the first stand 9 of the hot finishing rolling mill train may be replaced by the second stand of the hot finishing rolling mill train so as to bond the hot bands between these stands durin~ the finish-ing rolling.
Further, the bonding of the preceding and subsequent hot bands may be done in certain cases after an intermediate rol- -ling step following the hot rough rolling step.
; m us, the preceding and subsequent hot bands which have been passed through the intermediate rolling step are bonded between the hot finishing rolling step or during the continuous hot finishing rolling.
~he present invention will be more clearly understood from the following axamples.
A low-carbon steel slab of 250 mm in thickness and 10 m in length is continuously hot rolled to obtain a steel hot strip.
m e above low-carbon steel slabs were soaked to 1200C, reduced by the hot rough rolling mill train 1 to obtain steel hot bands of 30 mm in thickness, and these hot bands are successi-vely bonded one by one and continuously hot rolled under the con-" --11--- .. , . . . -- ' : ~ -: . '' ' ,. . .
1079~99 ditions shown in the table below.
No. 1 and No. 2 in the table are comparative examples in which no oxide scale-fusing agent was applied and the overlapped portions were temporarily fixed by the nail-like members. In Nos.
At a forward position in the advancing direction of the hot bands, there is positioned another X-ray measuring meter 6 above the hot band 3. When the forward edge of the hot band 2 is detected by the X-ray measuring meter 6 while it is r-unning and overlapping over the finishing end portion of the hot band 3, the lifting rod 13 of the hydraulic unit 11 is caused to get down to restore the delay table 10' to its original hoxizontal state, and at the same time the rotation control device of the rollers 12, 12' of the delay table 10, 10' is actuated to synchronize the running speed of the hot band 3 with that of the hot band 2. In this way the overlapping of the end portions of both bands is completed.
The overlapped portions run on the rollers 12" of the delay table 10" and are introduced into the first stand 9 of the , hot finishing rolling mill train, where the overlapped portions are bonded by the rolling reduction. During the rolling reduction, the oxide scale on the opposing surfaces of the overlapped portions :
, is squeezed out because it has been already,converted into the low melting point and fluid substance by reaction with the oxide scale-fusing agent, so that the base metal of the opposing surfaces is substantially exposed thereby and a metal-to-metal bonding is ob- ' ; tained'.' The bonding may be performed by a pressing means such as a rotary press (not shown) before the overlapped portions enter -the first stand 9.
The hot bands thus bonded are~cont'inuously finish-rolled in'the.hot finishing rolling mill train.
During the bonding of the overlapped portions by the rolling or the pressing, it someti~es occurs that the overlapped portions deviate from each other, increase in width, or warp.
~ f_10_ .. . . . . ...
-` ~079~99 Therefore, it is desirable that the overlapped portions are temporarily fixed as described below and then rolled or pressed to bond them.
As shown in Fig. 1, the hammering device 7 and the X-ray measuring meter 8 are arranged closer to the finishing rolling mill train than the X-ray measuring meter 6 . The X-ray measuring meter 8 detects the overlapped portion, namely, the lead end of the hot band 2 on which the tail end of the hot band 3 overlaps.
When the X-ray measuring meter 8 detects the lead head of the hot band 2 the detection signal is sent to the hammering device 7 , so that the hammering device 7 is actuated to drive the nail-like members successively into the overlapped portions of the tail end of the hot band 3 and the lead end of the hot band 2 . In this way, the overlapped portions of the tail end of the hot band 3 and the léad end of the hot band 2 are temporarily fixed. Then the temporarily fixed overlapped portions are introduced into the first stand 9 of the hot finish rolling mill train where the overlapped portions are bonded by the roll-ing reduction and then the hot bands thus bonded are continu-, , ously ! subjected;to the finishing rolling by the first and ,~
~' ' - :`
. ~; ' ' .
. . .
.
.
` ~ ' - ' : :
. . . ~. - .: .- .
107909g subsequent stands of the hot finishing rolling mill train.
The driving of the nail-like members 14 into the over-lapped portions may be done in such a manner as they penetrate just across the hot bands 2 and 3 as shown in Fig. 2 or in such a manner as they penetrate the hot bands 2 and 3 with both end projecting out the both surfaces, or penetrate partially across the overlapped por-tions as shown in Fig. 3(a) to (c).
In the above embodiment, the preceding and subsequent hot bands are bonded between the last stand of the hot rough rolling mill train and the first stand of the hot finishing rolling mill train to continuously produce the hot strip. However, without deviating from the scope and spirit of the present invention, the last stand 1 of the hot rough rolling mill train may be replaced by the first stand of the hot finishing rolling mill train, and the first stand 9 of the hot finishing rolling mill train may be replaced by the second stand of the hot finishing rolling mill train so as to bond the hot bands between these stands durin~ the finish-ing rolling.
Further, the bonding of the preceding and subsequent hot bands may be done in certain cases after an intermediate rol- -ling step following the hot rough rolling step.
; m us, the preceding and subsequent hot bands which have been passed through the intermediate rolling step are bonded between the hot finishing rolling step or during the continuous hot finishing rolling.
~he present invention will be more clearly understood from the following axamples.
A low-carbon steel slab of 250 mm in thickness and 10 m in length is continuously hot rolled to obtain a steel hot strip.
m e above low-carbon steel slabs were soaked to 1200C, reduced by the hot rough rolling mill train 1 to obtain steel hot bands of 30 mm in thickness, and these hot bands are successi-vely bonded one by one and continuously hot rolled under the con-" --11--- .. , . . . -- ' : ~ -: . '' ' ,. . .
1079~99 ditions shown in the table below.
No. 1 and No. 2 in the table are comparative examples in which no oxide scale-fusing agent was applied and the overlapped portions were temporarily fixed by the nail-like members. In Nos.
3 to 12, which are examples of the present invention, the bonding of the hot bands was done before the hot finishing rolling. In Nos.
13 and 14, which are also examples of the present invention, the bonding of the hot bands was performed during the hot finishing rol-ling.
As clearly shown in the table, although the temporary fixing by the nail-like members alone permits the subsequent conti-nuous hot rolling, a relatively large number of nail-like members are required for affording an enough bonding strength of overlapped portions which satisfactorily stands for the subsequent hot fini-shing rolling. The number of the nail-like members driven into the overlapped portions should be appropriate. If the number is too small, the nail-like members will be broken by the tension dur-ing the finishing rolling step so that the desired effects o the temporary fixing can not be obtained. On the other hand, if the num-ber is too large, the overlapped portions into which the nail-like members are driven would rupture during the finishing rolling due to too many penetrations by the nail-lide members.
, .
-:~79099 .. . .
Oxide* Over- Number Temp.at Steel Scale Amount lapp- of Press- Re- which NO. Width ~using ;ng Nail- Bond- duc- Bonding Material Agent Length like ing tion is Member Device Rate done Driven~
.
MM g/m2 mm %~C
Low Carbon 1200 - - 200 10 R.P.** 40 1050 Steel Slab 2 " 1200 - - 200 20 Fl*** 301045 3 " 1200 No.l 30 200 4 R.P. 401050 104 " 1200 No.1 30 200 - R.P. 401060 " 1200 No.1 30 200 4 Fl 301060 6 " 1200 No.2 100 100 4 R.P. 20 1040 7 " 1200 No.2 100 300 - R.P. 20 1050 8 " 1200 No.2 200 100 4 R.P. 20 1050 9 " 1200 No. 3 200 100 4 R.P. 20 1065 " 1200 No.4 200 100 4 R.P. 20 1055 11 " 1200 No.5 200 100 4 R.P. 20 1050 12 " 1200 No.6 200 100 4 R.P. 20 1050 ~13 " 1200 No.2 100 100 4 R.P. 40 1010 ; 20 14 " 1200 No.2 100 300 - R.P. 40 1010 * Composition of oxide scale fusing agent : -No-l B2O3(50%) - Na2B4O7t50%) No.2 : B2o3(45.6%) - SiO~(17.5%) 2 - A12O3(4.5%) - CaO(5.0%) - MgO(2.4%) No.3 : P2O5(60.9%) ~ B2O3(5-3%) K20 (16- %) -Na2O (9.8%) - Lio ~4.8%) - A12O3(3.2%) No.4 : NaCl No.5 : NaNO3 ` `
No.6 : Na2SO4 *!* R.P. = Rotary Press - . -1~79099 *** Fl = First stand of hot finishing rolling mill train According to the present invention in which the oxide scale-fusing agent is applied to the opposing surfaces of the over-lapped portions so that a strong bondage is achieved by pressure between the exposed metal of the opposing surfaces, thus affording a continuous and stable hot rolling operation even under the seve-re conditions in the subsequent hot finishing rolling step. Further, when the overlapped portions are temporarily fixed by the nail~ e members, it is possible to avoid the deviation of the opposing sur-faces of the overlapped portions, and the width increase and warplingof the overlapped portions so that an accurate and firm bondage can be obtained. It is also possible to reduce the length of the over-lapped portions and thus a good production yield can be assured.
.
. .
.
13 and 14, which are also examples of the present invention, the bonding of the hot bands was performed during the hot finishing rol-ling.
As clearly shown in the table, although the temporary fixing by the nail-like members alone permits the subsequent conti-nuous hot rolling, a relatively large number of nail-like members are required for affording an enough bonding strength of overlapped portions which satisfactorily stands for the subsequent hot fini-shing rolling. The number of the nail-like members driven into the overlapped portions should be appropriate. If the number is too small, the nail-like members will be broken by the tension dur-ing the finishing rolling step so that the desired effects o the temporary fixing can not be obtained. On the other hand, if the num-ber is too large, the overlapped portions into which the nail-like members are driven would rupture during the finishing rolling due to too many penetrations by the nail-lide members.
, .
-:~79099 .. . .
Oxide* Over- Number Temp.at Steel Scale Amount lapp- of Press- Re- which NO. Width ~using ;ng Nail- Bond- duc- Bonding Material Agent Length like ing tion is Member Device Rate done Driven~
.
MM g/m2 mm %~C
Low Carbon 1200 - - 200 10 R.P.** 40 1050 Steel Slab 2 " 1200 - - 200 20 Fl*** 301045 3 " 1200 No.l 30 200 4 R.P. 401050 104 " 1200 No.1 30 200 - R.P. 401060 " 1200 No.1 30 200 4 Fl 301060 6 " 1200 No.2 100 100 4 R.P. 20 1040 7 " 1200 No.2 100 300 - R.P. 20 1050 8 " 1200 No.2 200 100 4 R.P. 20 1050 9 " 1200 No. 3 200 100 4 R.P. 20 1065 " 1200 No.4 200 100 4 R.P. 20 1055 11 " 1200 No.5 200 100 4 R.P. 20 1050 12 " 1200 No.6 200 100 4 R.P. 20 1050 ~13 " 1200 No.2 100 100 4 R.P. 40 1010 ; 20 14 " 1200 No.2 100 300 - R.P. 40 1010 * Composition of oxide scale fusing agent : -No-l B2O3(50%) - Na2B4O7t50%) No.2 : B2o3(45.6%) - SiO~(17.5%) 2 - A12O3(4.5%) - CaO(5.0%) - MgO(2.4%) No.3 : P2O5(60.9%) ~ B2O3(5-3%) K20 (16- %) -Na2O (9.8%) - Lio ~4.8%) - A12O3(3.2%) No.4 : NaCl No.5 : NaNO3 ` `
No.6 : Na2SO4 *!* R.P. = Rotary Press - . -1~79099 *** Fl = First stand of hot finishing rolling mill train According to the present invention in which the oxide scale-fusing agent is applied to the opposing surfaces of the over-lapped portions so that a strong bondage is achieved by pressure between the exposed metal of the opposing surfaces, thus affording a continuous and stable hot rolling operation even under the seve-re conditions in the subsequent hot finishing rolling step. Further, when the overlapped portions are temporarily fixed by the nail~ e members, it is possible to avoid the deviation of the opposing sur-faces of the overlapped portions, and the width increase and warplingof the overlapped portions so that an accurate and firm bondage can be obtained. It is also possible to reduce the length of the over-lapped portions and thus a good production yield can be assured.
.
. .
.
Claims (11)
1. In a method for producing a hot strip by hot rough rolling, a steel slab heated to a rolling temperature to obtain a steel band, and hot finishing rolling the steel band in a conti-nuous manner, the improvements comprising overlapping a forward end portion of a steel band which is being rolled by the rough hot rol-ling over a finishing end portion of a similarly rolled preceding steel band before or during the hot finishing rolling step, with insertion between the overlapped portions of the both hot bands of an oxide scale-fusing agent which reacts with the oxide scale pre-sent on the opposing surfaces of the overlapped portions by the heat of the overlapped portions and forms a low-melting point sub-stance, bonding the overlapped portions by reduction, and subjecting the steel bands thus bonded to the hot finishing rolling continuous-ly.
2. In a method for producing a hot strip by hot rough rolling, a steel slab heated to a rolling temperature to obtain a steel band, and hot finishing rolling the steel band in a continuous manner, the improvements comprising overlapping a forward end por-tion of a steel band which is being rolled by the rough hot rolling over a finishing end portion of a similarly rolled preceding steel band before or during the hot finishing rolling step, with insertion between the overlapped portions of the both hot bands of an oxide scale-fusing agent which reacts with the oxide scale present on the opposing surfaces of the overlapped portions by the heat of the overlapped portions and forms a low-melting point substance, fixing temporarily the overlapped portions by means of a metallic nail-li-ke member driven into the overlapped portions, bonding the overlap-ped portions by reduction, and subjecting the steel bands thus bon-ded to the hot finishing rolling continuously.
3. A method according to claims 1 and 2, in which the steel band is subjected to an intermediate rolling after the hot rough rolling.
4. A method according to claims 1 and 2, in which the low melting substance formed between the overlapped portions is squeezed out of the overlapped portions during the reduction of the overlapped portions thereby removing the oxide scale from the opposing surfaces of the overlapped portions to expose substantially the base metal and causing bondage therebetween by metal-to-metal contact, so as to give the overlapped portions a bonding strength enough for standing against the rolling under tension in the subsequent hot finishing rolling step.
5. A method according to claims 1 and 2, in which the oxide scale-fusing agent is at least one selected from the group consisting of oxides, complex oxides, chlorides, sulfates, nitrates, carbonates and phosphates of Li, Na, K, Mg, Ca, Ba, B, A1, Si, Pb, P and Fe.
6. A method according to claims 1 or 2, in which the oxide scale-fusing agent is at least one selected from the group consisting of oxides, complex oxides, chlorides, sulfates, nitrates, carbonates and phosphates of Li, Na, K, Mg, Ca, Ba, B, A1, Si, Pb, P and Fe, the oxides and the complex oxides including a substance which decomposes at the temperature of the steel band to which it is applied to form an oxide.
7. A method according to claims 1 and 2, in which the oxide scale-fusing agent is applied to the steel band at a temperature not lower than 1000°C.
8. A method according to claim 2, in which the nail-like member has a strength higher than the strength of the overlapped portions of the hot band at the time of overlapping.
9. A method according to claim 2, in which the nail-like member is made of a material which will have a final strength equal to that of the overlapped portions of the hot bands when it is affected by the heat of the hot band.
10. A method according to claims 1 and 2, in which the reduction of the hot bands for their bonding is done by the hot finishing rolling mill stand or by a separate reduction means.
11. A method according to claims 1 and 2, in which the reduction of the hot bands for their bonding is done when the hot bands are at a temperature higher than 1000°C.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11197576A JPS5820681B2 (en) | 1976-09-18 | 1976-09-18 | Hot endless continuous rolling method for steel strip |
| JP52051743A JPS587398B2 (en) | 1977-05-07 | 1977-05-07 | Hot joint method for steel materials |
| JP9657877A JPS5855844B2 (en) | 1977-08-13 | 1977-08-13 | Continuous hot rolling method for steel materials |
| JP9657777A JPS5855843B2 (en) | 1977-08-13 | 1977-08-13 | Hot joint method for steel materials |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1079099A true CA1079099A (en) | 1980-06-10 |
Family
ID=27462681
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA286,896A Expired CA1079099A (en) | 1976-09-18 | 1977-09-16 | Method for producing a steel strip by hot rolling |
Country Status (8)
| Country | Link |
|---|---|
| AU (1) | AU507448B2 (en) |
| BE (1) | BE858765A (en) |
| BR (1) | BR7706215A (en) |
| CA (1) | CA1079099A (en) |
| DE (1) | DE2742151C2 (en) |
| FR (1) | FR2364704A1 (en) |
| GB (1) | GB1588468A (en) |
| NL (1) | NL168433C (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE69206188T2 (en) * | 1991-04-26 | 1996-03-28 | Hitachi Ltd | Method and device for joining heated tapes. |
| JP3784948B2 (en) * | 1997-12-05 | 2006-06-14 | 三菱重工業株式会社 | Method and apparatus for suppressing surface oxide film during hot finish rolling |
| WO2017140886A1 (en) | 2016-02-17 | 2017-08-24 | Sms Group Gmbh | Device and method for the friction welding of warm metallic products |
| DE102017213986A1 (en) | 2017-08-10 | 2019-02-14 | Sms Group Gmbh | Apparatus and method for friction welding warm metallic products |
Family Cites Families (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE544607C (en) * | 1927-10-11 | 1932-02-20 | Robert Victor Neher A G | Method and device for stapling together metal foils in web form |
| US1940939A (en) * | 1928-06-04 | 1933-12-26 | United Eng Foundry Co | Metal working |
| US2761208A (en) * | 1952-02-28 | 1956-09-04 | Colin C Mitchell | Method of producing metallic strip |
| GB745426A (en) * | 1952-03-24 | 1956-02-29 | Metals & Controls Corp | A method of solid-phase bonding metals |
| DE1730132U (en) * | 1956-01-27 | 1956-09-20 | Huettenwerke Ilsede Peine A G | DEVICE TO COMPENSATE FOR FEED DIFFERENCES OF AN ENDLESS ROLLED PRODUCT TO BE WELDED TOGETHER FROM INDIVIDUAL STUDS. |
| FR1206203A (en) * | 1957-05-15 | 1960-02-08 | Reynolds Metals Co | Improvements in cold compression welding processes for metals and alloys |
| SE302280B (en) * | 1966-02-01 | 1968-07-15 | Svenska Metallverken Ab | |
| DE1932665A1 (en) * | 1969-06-27 | 1971-01-07 | Duerrwaechter E Dr Doduco | Process for the surface bonding of metallic materials |
| FR2077716A1 (en) * | 1970-02-09 | 1971-11-05 | Wendel Sidelor | |
| JPS51112459A (en) * | 1975-03-29 | 1976-10-04 | Nippon Steel Corp | Continuous hot rolling method |
| FR2335301A2 (en) * | 1975-12-17 | 1977-07-15 | Kloeckner Werke Ag | Alloy steel cladding welded onto steel slabs - using alternate austenitic and ferritic welding passes to reduce mfg. costs |
-
1977
- 1977-09-13 GB GB3811477A patent/GB1588468A/en not_active Expired
- 1977-09-13 AU AU28749/77A patent/AU507448B2/en not_active Expired
- 1977-09-16 BE BE2056253A patent/BE858765A/en not_active IP Right Cessation
- 1977-09-16 CA CA286,896A patent/CA1079099A/en not_active Expired
- 1977-09-16 NL NL7710191A patent/NL168433C/en not_active IP Right Cessation
- 1977-09-16 FR FR7727985A patent/FR2364704A1/en active Granted
- 1977-09-16 BR BR7706215A patent/BR7706215A/en unknown
- 1977-09-19 DE DE19772742151 patent/DE2742151C2/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| NL7710191A (en) | 1978-03-21 |
| NL168433B (en) | 1981-11-16 |
| DE2742151C2 (en) | 1983-11-17 |
| NL168433C (en) | 1982-04-16 |
| BR7706215A (en) | 1978-05-09 |
| GB1588468A (en) | 1981-04-23 |
| DE2742151A1 (en) | 1978-03-30 |
| AU2874977A (en) | 1979-03-22 |
| FR2364704B1 (en) | 1981-04-10 |
| BE858765A (en) | 1978-01-16 |
| AU507448B2 (en) | 1980-02-14 |
| FR2364704A1 (en) | 1978-04-14 |
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