CA2366299C - Surface cutting of hot-rolled steel products - Google Patents

Abstract

In cutting the top and bottom surfaces of a hot-rolled steel sheet by the rotation of milling cutters holding the sheet therebetween in the thickness direction of the sheet in the running process of the hot-rolled sheet, the cutting resistance is determined by the cutting conditions including the type of hot-rolled sheet, the temperature in cutting, and the cut depth is controlled by the adjustment of cut depth, and cutting is performed by making the tension produced on the hot-rolled sheet by the cutting resistance lower than the breaking strength of the joint portion to prevent the breakage of hot-rolled sheet.
The apparatus employed includes a moveable sheet passing guide for holding the hot-rolled steel product during passage of the product from the input side to the output side of the milling cutter pair.

Description

1.
SURFACE CUTTING OF HOT-ROLLED STEEL PRODUCTS
This is a division of our co-pending Canadian Patent Application No. 2,200,740 filed July 23, 199.6.
The present invention relates to a method., and apparatus for surface cutting of hot-rolled steel products, especially of wide hot-rolled 'bong sheets, and a method and apparatus for surface cutting which are advantageous in removing raised portions ,(projections) and burrs produced in a joint region by butt joint of semi finished steel products such as sheet bars, slabs, billets, and blooms.
BACKGROUND ART
Regarding the technologies for making a repair of flaws produced on the surface of hot-rolled steel products such as sheet bars during the hot rolling process and for removing projections inevitably produced. in the joint portion in the continuous hot rolling process in which rolling is carried out by butt joining the tail edge of preceding steel product to the leading edge of following steel product, many proposals have already been made in:
Unexamined Japanese Patent Publication No. 57-137008, Unexamined Japanese Patent Publication No. 63-160707, Unexamined Japanese Patent Publication No. 5-23706, Unexamined Japanese Patent Publication No. 5-104261, Unexamined Japanese Patent Publication No. 57-91856, Unexamined Japanese Patent Publication No. 53-112593, and so forth.
However, these technologies have disadvantages that there arises a trouble of breaking of a hot-rolled steel product (hereinafter referred simply as to a steel product) in surface cutting the steel product, and that the improvement in cutting efficiency cannot be achieved because the life of cutting edge is short and quick action cannot be taken when local wear of cutting edge occurs. Also, there remain problems in that it is difficult to adjust a predetermined allowance in cutting a steel product, that the equipment is damaged by the contact of cutting edges which cut a steel product from upside and downside, that chips produced by cutting cannot be disposed well, and that fluttering of steel product occurs during the cutting process.
SUMMARY OF THE INVENTION
The present invention provides a surface cutting apparatus for hot-rolled steel products that cuts top and bottom surfaces of a hot-rolled steel product continuously or intermittently by passing said steel product in a sheet passing plane between a pair of rotary cutting drums rotating in a direction reverse to each other, said apparatus having a movable sheet passing guide that is supported to be selectively movable and insertable between a lower one of the pair of rotary cutting drums and the sheet passing plane before a leading edge of the hot-rolled steel product reaches the pair of rotary cutting drums to hold the hot-rolled steel product during a period of time when the leading edge of the steel prc>duct advances from an input side to an output side of the rotary cutting drum pair.
The invention will further be described, by way of example only, with reference to the accompanying drawings wherein:
Fig. 1 is a side view showing a state of surface cutting of a steel product;
Fig. 2 is a plan view of Fig. 1;

Fig. 3 is a schematic view of a continuous hot-rolling facility;
Fig. 4 is a view showing a state of cooling at the leading edge of cutting edge of a rotary drum;

Fig. 5 is a diagram showing t~-ae relationship between the circumferential speed of milling c~-utter and the pressure of cooling water;
Fig. 6 is a diagram showing the relationship between the outside diameter of milling cutter and the pressure of cooling water;
Fig. 7 is a view showing a overall configuration of cutting apparatus;
Fig. 8 is a view showing a construction of: rotary dry of the conventional construction;
Fig. 9 is a view showing another construction of rotary drum of the conventional construction;
Fig. 10 is a view for illustrating the configuration of a cutting apparatus in accordance with the present invention;
Fig. 1l is views taken along the lines A-A and B-B
of Fig . 10 ;
Fig. 12 is a view showing only a rotary drum for the apparatus in accordance with the present invention;
Fig. 13 is a view showing only another rotary drum for the apparatus in accordance with the present invention;
Fig. 14 is a view showing a fixing construction of disks;
Fig. 15 is a view showing the principal portion of cutting edge;
Fig. 16 is a view for illustrating a construction of another rotary drum for the apparatus in accordance with the present invention;
Fig. 17 is a view for illustrating a construction of still another rotary drum for the apparatus in accordance with the present invention;
Figs. 18(a) and 18(b) are enlarged views of principal portion of the rotary drum shown in Fig. 17;
Fig. 19 is a diagram showing a positional change of rotary drum with time;
Fig. 20 is a view showing a surface cutting state of a steel product;
Fig. 21 (a) is a diagram showing a load degree of rotary drum in the drum width direction, and Fig. 21(b) is a view showing the outside diameter of rotary drum;
Fig. 22 is a view showing a configuration of the apparatus in accordance with the present, invention, which can prevent the breakage of cutting edge and can recognize the gap between drums;
Fig. 23 is a view showing another configuration of the apparatus in accordance with the present invention, which can prevent the breakage of cutting edge and can recognize the gap between drums;
Fig. 24 is a view showing still another configuration of the apparatus in accordance with the present invention, which can measure the wear amount of cutting edge;
Fig. 25 is a view showing an example in which measuring means are disposed on the upside and downside of rotary drum;

w Fig. 26 is a view showing another example of cutting apparatus in accordance with the present invention;
Fig. 27 is a chart showing a specific procedure carried out when zero adjustment is made;
Fig. 28 is a view showing a typical arrangement of apparatuses for a continuous hot rolling facility;
Fig. 29 is a view showing a state of the joint portion of steel products when continuous hot rolling is performed;
Fig. 30 is a view showing a state in which the joint portion shown in Fig. 29 has been rolled;
Fig. 31 is a view showing a state in which the joint portion of steel product is cut;
Fig. 32 is a view showing a state in which chips produced in cutting steel products are disposed;
Fig. 33 is a view showing a configuration of a continuous hot rolling facility in which the cutting apparatus in accordance with the present invention is arranged;
Fig. 34 is a view taken along the line II-II of Fig. 33;
Fig. 35 is a view taken along the line III-III of Fig. 34;
Fig. 36 is a view showing a state in which the leading edge of steel product hangs down;
Fig. 37 is a view showing a configuration of the side of the cutting apparatus in accordance with the present invention;

Fig. 38 is a view taken along the line III-III of Fig. 37; .
Fig. 39 is a view showing a state in which a steel product flutters during the cutting process;
g Fig. 40 is a view showing a basic configuration of an apparatus for restraining the fluttering of steel product during the cutting process;
Fig. 41 is a view showing a basic configuration of another apparatus for restraining the fluttering of steel 1p product during the cutting process;
Fig. 42 is a view showing the relationship between cutting resistance and cutting resistance reaction in surface cutting of steel product; and Fig. 43 is a diagram showing a comparison between the 15 case where cutting is performed by holding down a steel product and the case where cutting is performed without holding down.
BEST MODE FOR CARRYING OUT TFiE INVENTION
In hot rolling, when rolling is performed 20 continuously by joining the tail edge of a preceding sheet to the leading edge of a following sheet between, the rough rolling and the finish 'rolling to achieve a high efficiency, a method for finishing the sheet surface, in which the raised portion including the front and rear regions thereof is 25 surface-cut by milling, has been used practically. At present, however, the cut depth in milling is the same for all objects, and special consideration is not given.

, 64881-449E
Therefore; when the cutting resistance is varied greatly by the type, temperature; etc. of sheet, a trouble such that the sheet is broken at the joint portion having a low breaking strength occurs. As the technology for removing the raised portions (projections) at the sheet joint portion, a method has been proposed in Which the weld is detected by a detector, a cutting apparatus is activated by the detection signal , and weld burrs are removed while the sheet is runni=ig, as in Unexamined Japanese Patent Publication No. 53-112593 (Method for Removing Weld Burrs of Sheet) . Also, a method has been proposed in Which the projections at the joint portion are cut by cutting edges of a surface treatment apparatus provided before a hot rolling mill, as in Unexamined Japanese Patent Publication No. 53-160707 (Hot Rolling Equipment).
However, it is very difficult to overcome the trouble of breakage of joint portion by these methods.
The present invention solves the above problem by using the means described in 1) to 4). Specifically,: the cutting resistance defined by the cutting conditions (type of steel (chemical composition), temperature, sheet width, sheet thickness, running speed, ratating direction of milling cutter, circuraferential speed of cutting edge, cut depth, etc. ) for the milling cutter is controlled by the adjustment of cut depth, and the tension produced on the steel product by the cutting resistance is decreased to a value lower than the breaking strength of the joint portion to prevent the breakage of the steel product. The following is g _ a a specific description of this point for the case of sheet as an example.
Figs. 1 and 2 are a side view and a plan view, respectively, showing a state in which the surface of a running sheet is cut by milling cutters.
In Figs. 2 and 2, reference numeral 1 denotes a milling cutter having cutting edges at the tip end thereof, 2 denotes a sheet, 3 denotes a position control cylinder for milling cutter, 4 denotes a thermometer, 5 denotes a process computer, 6 denotes a control panel, and 7 denotes a joint portion of sheet 2 . Arrow A indicates the running direction of sheet 2, arrow B indicates the rotating direction of mi111ng Cutter 1, and arrow C indicates the direction of tension caused on the sheet 2 by the cutting resistance.
Reference character b denotes the width of sheet 2, T denotes the thickness of sheet 2, t denotes the cut depth on one side produced by milling cutter 1, and w denotes the enjoined length at the edge in the sheet width direction at the j oint portion 7. .
Fig. 3 is a view showing a typical arrangement of a cutting apparatus having the milling cutters in accordance with the present invention.
In Fig. 3, the sheet (sheet bar) rolled by, for example, a rough rolling mill 8 iS wOUnd by a winding/rewinding device 9 , the edge of respective sheets Sl and S2. is cut into a predetermined shape by a cutting device 10 (drum shear etc. ) on the input side of a scale breaker (not shown) and a hot finish rolling mill 13 (F1, F2, F3, . . . ) while the sheet is rewound by the winding/rerainding device 9, the tail edge of the preceding sheet S1 and the leading edge of the following sheet S2 are arranged ~.n an opposed relation with a small gap being provided therebetween, and then the nearby region is held in the sheet thickness direction by clamps lla and llb mounted on a movable joining device 1l.
In this state, the sheets are joined by pressing by means of a pressing means (the clamps lla and llb can be moved so as to be closer to each other) while being induction heated by, for example, an inductor for induction heating located at at least one position of just above and just below the portion to be joined or after being induction heated. After the raised portions caused by this joining operat:a.on including the front and rear regions thereof are surface-finished by a milling device 12, the rolling is performed.
In the case where surface cutting is performed between the rough rolling mill 8 and the finish rolling a~i.ll 13, the tension produced on the sheet. by cutting resistance acts between.the milling cutter 1 and the downstream-side finish rolling mill 13 when the rotating direction of the milling cutter 1 is the direction as shown in Figs. 1 and 2 (up cut), and the tension acts between the milling cutter l and the upstream-side coil winding/rewinding device 9 when 'tee rotating direction of the milling cutter is reverse to the above (down cut) .
The sheets are joined usually by the: induction heating process, in which unjoined portions are formed in the sheet width direction at present for various reasons caused by the fact that heating is not uniform in the sheet width direction. Therefore, the joint portion 7 has a -lower breaking strength than the base metal because the joint portion is hotter tharu the base metal due to heating in joining (base metal: about 900°C, joint portion: about 1300°C) and the joint portion has the enjoined portions.
According to the present invention, in Figs: 1 and 2, the information about the data on sheet 2 (steel type, sheet width b, sheet thickness T) is given to the control panel 6 by the process computer 5 to which these data are inputted, a temperature signal of the running sheets (S1, SZ) is sent from the thermometer 4 installed on the apparatus input side to the control panel 6, and the cut depth t on one side is determined at the control panel 6! based on the signal .
The milling cutter position control cylinders 3 are activated by the signal from the control panel 6, and cutting of the cut depth.t determined as described above is performed by using milling cutters 1.
then the joint portion 7 including the front and rear regions thereof is surface-cut, the joint portion 7 is detected by sudden rise in temperature on the thermometer 4 and the milling cutter position control cylinders 3 are activated through the control panel 6 based on the temperature signal, by which the surface cutting of that portion can be performed reliably. At this time, it is 64~~g-449F
important to appropriately determine the distance between the thermometer 4 and the milling cutter 1 by considering time lag etc.
The surface cutting of the joint portion 7 including the front and rear regions thereof of the sheet 2 is important not only to the removal of projections at the joint portion 7 and the nearby regions thereof but also to the removal of misalignment produced in the sheet thickness direction at the . j oint portion, clamp flaws , new scale , etc . Accordingly, it is essential to cut to a depth such that these defects can be removed.
The procedure for deriving an experimental equation for determining the cut depth in the case of up cut as shown in Fig. 2 is as follows.
First, using the strength of joint portion 7: Qb (kgf /mm2 ) , unj oined length : w (mm) , cut depth : t (mm) , width of sheet 2 : b (mm) , and sheet thickness : T (mm) , -the breaking strength of the joint portion 7: fb (kgf) can be. expressed as fb = Qb ~ (b-2w) ' (T-2t) ... (3) where the above fb and Qb are values for which teiaperature is considered.
On the other hand, the relationship between the cut resistance for each steel type: k (kgf/mm2) and the temperature of sheet during cutting: Tk(°C) is given by experiment as k = C ' exp [A/ (Tk+273) ] . . . (4) where C (kgf/mm2) and A (°C) are constants determined by the steel type of sheet 2. From Eq. (4) , using the running speed of sheet 2: VM (mm/s) and the circumferential speed of milling cutter cutting edge: Vc (mm/s), the cutting resistance: fa (kgf) is expressed as f$ = k ~ b ~ t ~ VM/Vc . . . (5) Using Eqs. (3) , (4) , and (5) and considering safety factor: Sf (2 - 5, it is especially important to consider the deterioration in breaking characteristics caused by notch effect of unj oined portion) , the cut depth : t (mm) such that the joint portion 7 is not broken by cutting can be determined as follows 2Sf - f$ = fb ... (6) Substitution of Eqs. (3) , (4) and (5) in Eq. (6) yields 2Sf ~ C - exp [A/ (Tx+273) ] - b ~ t - VM/Vc - Qb - (b-2w) - (T-2t) , ~
Theref ore , t = Qb ' (b-2w) ~ T/ ~ 2Sf C - exF~ [A/ (Tx+273) - b ' VM/Vc + 2 U b ' (b-2w) } . . . ( 8 ) can be derived.
In the case of down cut in which the rotating direction of milling cutter l is reverse to the direction shown in Fig. 2, since the tension acting on the sheet 2 by the cutting resistance fa is on the input side of the milling cutter 1, the effective sheet thickness is equal to sheet thickness: T (the projections at the joint portion 7 are ignored}, so that the above-described equation (3) is expressed as fb - Ub - (b-2w) ~ T - ... (9) Therefore, 2Sf ~ C ' exp [A/ (Tx+273) ] - b - t VM/vc - Qb - (b-2w) ~ T ... C10) From this equation, t = Ur ' (b-2w) - T/ ( 2Sf - C - ~'-xp (Al (Tx+273) ]
- b - vM/vc) ... (11) is derived.
In deriving the above equations for calculating. the cut depth t, the raised portions at 'the joint potion 7 are ignored in both cases of up cut and down cut. This is because under the ordinary process conditions, although the. joint portion 7 has a substantially great cut depth, the cutting resistance is low because of high temperature. This ~is apparent from the fact that breakage of the joint gortion 7 does not occur at all in cutting the joint portion 7 (raised portions) in the actual process.
For the sheets of various steel 'type including extra low carbon steel and SUS304 stainless steel, tyke surface cutting was performed between the rough rollirig and the finish rolling in the hot rolling, and the cut depth t was controlled so as to be a value smaller than the value calculated from Eq. (8) in the case of up cut and from'Eq.
(11) in the case of down cut. As a result, the breakage of the joint portion does not occur at all.
The following is a description of a case where the life of milling cutter used for surface cutting of sheets is prolonged and stable surface cutting is performed while preventing loading etc. by using the means described in the above item 5).
The surface finishing of slabs and hot-rolled plates is performed by using a grinder having a grindstone as disclosed in Unexamined Japanese Patent Publication No. 57-91856. Such a grinder has a low work efficiency when grinding a wide, long ob'ect such as a plate. Especially When the slab surface is finished by the grinder in direct rolling, a high energy loss is produced because the steel product being finished stays for a long period of time and the heat thereof dissipates in the air. On the other hand, a milking cutter type cutting edge having a drum length which covers the overall range in the plate width direction has been used as a means for improving the cutting effici:ency.; When a non-ferrous maternal such as ceramics and tungsten carbide is used for such a cutting edge, the life of cutting edge is greatly shortened by wear, causing the cost to climb.
Alternately, when a ferrous cutting edge is used, the problem with the cutting edge of non-ferrous material such as ceramics and tungsten carbide is eliminated, but'chips are liable to adhere to the cutting edge, so that the heat input from chips to cutting edge causes a melting loss, and also a stable operation cannot be performed for a long period of time because loading or clogging of cutting edge occurs easily.

In the present invention, therefore, when the surface cutting of sheet is performed using a ferrous milling cutter, cooling water is sprayed to tie cutting face or flank of milling cutter at a pressure in accordance with the rotating speed and outside diameter, by which the life of the milling cutter used for the surface cutting of;slabs and sheets such as hot-rolled sheets (hoops) is prolonged, and stable surface cutting to prevent loading can be achieved.
By spraying cooling water to the cutting face or flank of cutting edge at a hydraulic pressure in accordance with.the rotating speed and outside diameter of. the milling cutter, high-temperature chips adhering to the cutting edge by cutting can be removed instantly by the centrifugal force caused by the rotation of BLl.lling cutter and the pressure of water, so that the heat input from the deposits at the cutting edge is decreased greatly. Therefore, the life of milling cutter is increased remarkably and the loading of cutting edge caused by the deposits is eliminated.
The centrifugal force Fw generated by the rotation of milling cutter is expressed as Fw = m (~Ir) . (12) where m: mass of chips V: rotating~speed of milling cutter r: 1/2 of outside diameter of milling cutter.
Also, the cooling water power Fp is expressed as Fp = 1/2 ~ q~ = a (PlIp2) 3/2 . . . (13) where q: mass of water - Zs -v.: colliding speed of water a: constant determined from the flow rate at reference pressure Pl of water according to the nozzle model specification P2: supply pressure of Water Therefore, in order to .remove the chips deposited in cutting by using a milling cutter, cooling water should be sprayed so that the pressure of cooling water satisfies the following equation.
(FW + Fp) /A > ~a . (14) where A: cross sectional area of chip deposit Us : high-temperature tensile strength of sheet-The following is a description of a case where the milling cutters 14a and 14b are rotated by the drive of the shafts 15a and 15b, respectively, and cooling water is sprayed from a nozzle 16 to the cutting face thereof as shar~m in Fig. 4.
Fig. 5 shows the result of eacperiment in which the cooling water pressure such that the melting loss and loading of cutting edge do not occur is deterxdined with the outside diameter of milling cutter being set at 800 mu and the cireumferential speed thereof being varied in the range of 20 to 120 m/sec. In this figure, the solid line indicates the lower limit value of cooling water pressure when the flow rate is Q; and the broken line indicates the iawer limit value of cooling water pressure when the flow rate is 2Q.
Fram this , it is found that the centrifugal force Fw increases with the increase in circumferential speed of milling cutter, so that the melting'loss and loading of cutting edge do not occur even if the cooling water power Fp is decreased by the decrease in cooling water pressure.
That is, it is preferable that the cooling water pressure decrease with the increase in the circumferential speed of milling cutter. Also, this figure indicates that the cooling water pressure should be adjusted in the range of 3 to 300 kgf/cm2 for the circumferential speed of milling cutter in the range of 20 to 120 m/sec.
Fig. 6 shows the result of experiment in which the cooling water pressure such that the melting loss and loading of cutting edge do not occur is determined with the circumferential speed of milling cutter being fixed at 20 m/sec and the outside diameter thereof being varied in the range of 200 to 1000 imn. In this figure, the solid line indicates the lower limit value of cooling water pressure when the flow rate is Q, and the broken line indicates the lower limit value of cooling water pressure when the flow rate is 2Q.
From this, it is found that since the centrifugal force Fw decreases in inverse proportion as the outside diameter of milling cutter increases, the melting loss and loading of cutting edge a.s not produced by the increase in cooling water pressure as the power of three by two (the increase in cooling water power Fp).
That is, it is preferable that the cooling water pressure increase with the increase in the diameter of milling cutter. This indicates that cooling water; according to the rotating speed and outside diameter of milling cutter should 'be sprayed to the cutting ~ facie of milling cutter .
On the other hand, it is found from Figs . 5, and 6 that when the quantity of cooling water is doubled, the cooling Water pressure such that the melting loss and loading of cutting edge do not occur decreases . This is probably because the quantity of water colliding with the cutting edge per unit time is increased by the increase in flow rate.
The rotating speed of milling cutter should preferably be 20 to 120 m/sec. The x:eason for this is that if the rotating speed of milling cutter. is lower than 20 m/sec, the speed is decreased and the milling cutter is stopped by the cutting resistance, whale i:f the rotating speed of milling cutter is higher than 120 m/sec, the vibration frequency due to the number of revolutions becomes equal to or higher than the critical speed, so that the machine resonates, sometimes being destroyed.
The outside diameter of milling cutter should preferably be 600 to 1000 mm. The reason for th~.s is that if the outside diameter is smaller than 600 mm, the number of revolutions for achieving the circumferential speed increases; so that the vibration :~rec~uency exceeds the critical speed, or the drop in speed due to cutting resistance is great, so that the milling cutter is stopped, while if the outside'diameter is larger than.1000 uaa, though the large _ 19 _ outside diameter is advantageous in terms of vibration because of the decrease in the number of revolutions, the centrifugal force decreases, so that the melting loss and loading of cutter edge are liable to occur, and the motor output for driving increases.
In the above explanation, the: case Where cooling water i sprayed to the cutting face of cutting edge has been described. The case where cooling water is sprayed to the flank of milling cutter is the same, so that the explanation thereof is omitted.
Fig. 4 , which has been mentioned before, shows a case where surface cutting of steel product is performed using ferrous. milling cutter by spraying cooling :water to the cutting face of milling cutter. In this figure, reference numerals 14a and 14b denote milling cutters, 15a and 15b denote main shafts, l6 denotes a spray nozzle for cooling water, 17 denotes a bearing for rotatably supporting the milling cutter 14a, 14b, 18 denotes a screw down cylinder, 19 denotes a housing;, 20 denotes a power transmission spindle, 21 denotes a pinion stand, and 22 dentes an electric motor. Fig. 7 shows the overall configuration of a facility in which the milling cutter is incorporated.
Investigation was made on the state of melting loss and loading of cutting edge for the case where surface cutting of a slab of 120 mm thick and 800 mm wide was performed by rotating a ferrous milling cutter with a diameter of 800 mm at a speed of 65 m/s and by spraying cooling water With a flow ' ~~~~~'~'~~~' a rate of 500 .~/min/m and a pressure of 50 kgf/cm2 to the cutting face, and for the conventional method zn which the circumferential speed of milling cutter was 20 m/sec and the pressure of cooling water Was 3 kgf/cm2 (other conditions were the same as those of the present invention) . The result was that the melting loss and loading of cutting edge did not occur at all for about 72 hours in the method in accordance with the present invention, though the life of milling cutter was about 30 minutes in the conventional method, and,it was confirmed that the life of milling cutter can be prolonged to about 30 days.
The example in which cooling water was sprayed to the cutting face of milling cutter is as follows : By using a slab with the Saab size as. that described above, investigation was made on the state of melting loss and loading of cutting edge for the case where surface cutting of wasw performed by rotating a ferrous milling cutter with a d3.ameter of 800 ~
at a speed of 65 m/sec and by spraying cooling water with a flow rate of 500 1/min/m and a pressure of 50 kgf/cm2 to the cutting face; the case being in accordance with the present invention, and for the conventional method in which surface cutting was performed by rotating a ma.lling cutter with the same diameter at a speed of 20 m/sec by spraying coo3ing water with a flow rate of 500 1/min/m and a pressure of 3 kgf/cm2 (other conditions were the same as those of the present invention). The result was that the .life of milling cutter could be, prolonged to about 30 days in this case as well.

~~~~~~~'~~~r In this example, investigation was made for the case where the tail edge of preceding sheet ' and the leading edge of following sheet were butt joined and the resultant projections were cut. In this case as well, it was confirmed that the life of milling cutter can be prolonged remarkably as compared with the conventional method.
The following is a description of a case where the repair or replacement of milling cutter is easily made wrhen the life of milling cutter, which is used for the surface cutting of sheet by using the means described in the above items 6) to 9) , has been expired.
Regarding the technologies for making a repair of flaws produced on the surface of sheets during the hot rolling process and fox removing projections inevitably produced in the joint region in the continuous hot rolling process in which rolling is carried out by butt joining the tail edge of preceding steel -product to the leading edge of following steel product, as described before; many proposals have already been made in Unexamined Japanese Patent Publication No. 57-137008, Unexamined Japanese Patent Publication No. 63-160?07, Unexaau.ned Japanese Patent Publication No. 5-23706, Unexamined Japanese Patent Publication No. 5-104261, and so forth. Usually, cutting is'performed by using a rotary drum of milling cutter type which is about 100 mm wider than the object to be cut. Such a drum is generally a drum which is integral with a main shaft portion whose both ends are supported via bearings as showzy in Fig. 8 ~~~~~'-~~~~
(centrifugal casting etc.), or a drum which is mounted to a main shaft via a key as shown in Fig.- 9.
For the rotary drum of such a construction, especially the rotary drum integral with the main shaft; even when a partial repair of cutting edge only (for exaatple, work of reinstalling cutting edge on the roll drum) is made, troublesome work of removing the rotary drum together with the main shaft is needed, so that it is difficult to improve the efficiency of work including the assembling work.
For the rotary drum which is mounted to the main shaft via a key, since the main shaft and the drum are separate, the mounting and dismounting,of rotary drum are easy as compared with the integral type. However, since the rotary drum rotates together with the main shaft, it is necessary to strictly set the fitting tolerance to decrease the runout of rotary drum in the rotation of main shaf t . For this reason, a.t is difficult to mount the rotary drum to the main shaft.
When the rotary drum is deformed or when seizure occurs between the rotary drum and the main shaft, the rotary drum must be replaced together with the main shaft, so that the problem still remains.
In the present invention, therefore, as a cutting device, a configuration is used in which a plurality;of disks , each of which has cutting edges at the whole outer periphery and detachably fits to a main shaft, are arranged on a paa.r of main shafts which hold a sheet therebetween in the sheet thickness direction and rotate in the direction reverse to each other . For the disks , the phase of cutting edges on the adjacent disks is shifted in the circ.~uinferential direction, and the cutting edges are arranged discontinuously in the axial direction. Also, the disks are fixed by expanding the main shaft diameter. Further, the main shaft has a contracting mechanism for instantly contracting'the shaft diameter if an overload is applied. to the disk. These features are especially advantageous in the present invention.
A plurality of disks having cuttW g edges at the whole outer periphery are arranged along the axis of the main shaft (the number of disks covers the entire range of object to be cut), and these disks are bound to configure a rotary drum. Thereupon; the mounting and dismounting of rotary drum can be performed very easily,, and when the life of cutting edges has locally been expired, only the corresponding disks can be replaced.
By shifting the phase of cutting edges on the adjacent disks in the circumferential direction and by arranging the cutting edges discontinuously in the axial direction, the length of chip produced in cutting the sheet surface can be decreased, so that there is no risk of damaging the cutting edge by entanglement of chips around the cutting edge, and also the chips can be removed relatively easily.
Even about 1 to 2 aun of shift of cutting edges on the adjacent disks can be expected to achieve sufficient effect, but the cutting edges can be shifted to about 1/2 of cutting edge pitch (the distance between cutting edges disposed at the outer periphery of disk).
The disks are fixed to the main shaft by the expansion of main shaft, and removed from the main shaft by the contraction of main shaft, so that the tolerance of fitting to the main shaft need not be set so strictly as before.
The expansion and contraction of main shaft can be performed, for example; by making the interior of main shaft 'hollow, and by pouring or discharging hydraulic oil into or from the interior to regulate the pressure in the main shaft.
If an excessive load is applied to the cutting edge during the sheet cutting process , the damage to cutting edge cannot be avoided. Therefore, it is especially effective to provide a contracting mechanism in which, for- example, a striker is provided on the side of a disk fixing flange;. a plug'-is provided on the main shaft close to the striker, and the plug is allowed to be dropped from the maa.n shaft by the striker to decrease the pressure in the main shaft when a force of some amount is applied to the cutting edge and the disk tries to rotate around the main shaft, by which the shaft diameter is instantly contracted.
Figs. 10 and 11 show a sheet surface cutting apparatus in accordance with the present invention: In these-figures; reference character S denotes a sheet, 23a and 23b denote main shafts which hold the sheet S therebetween in the sheet thickness direction and rotate in the d~.rection reverse to each other, and 24a and 24b denote rntary drums. The rotary drum 24 consists of a plurality of disks i1 . . ii each of which has cutting edges at the whole outer periphery thereof-and fits detachably to the main shaft 23a, 23b . These disks i1 . . .
i;. are fixed and held by flanges etc.
Reference numeral 25 denotes a bearing for rotatably holding the main shaft 23a, 23b, and 26 denotes a liquid-operated cylinder for moving the main shaft 23a, 23b together with the bearing 25. By operating the liquid-operated cylinders 26, the gap between the rotary drums 24a and 24b is adjusted.
Reference numerals 27a anr3 27b denote driving motors, 28a and 28b denote universal joints for connecting the driving motor 27a, 27b to the main shaft 23a, 23b, 29 denotes a joint portion position detector, and 30 denotes a controller for controlling the rotational speed of the driving motor 27a, 27b, and operating the liquid-operated cylinders 26 based on the measurement result of the joint portion position detector 29.
Fig. 12 shows the rotary drum 24a,, 24b only. As shown in this figure, in the present invention; the rotary drum 24a, 24b is so configured that a plurality of disks i1 . . . i;, are arranged on the main shaft 23a, 23b, so that the mounting and dismounting of rotary drum can be performed easily.
As shown in Fig. 13, the main shaft 23a, 23b is tapered; and the disks i1 ... ii are mounted on a-sl~eve 31 fitting to this taper and bound and fixed firmly by the flanges and lock nuts etc., by which the looseness between the disk and main shaft as well as the looseness between disks can be eliminated, and moreover the mounting and dismounting of disk can be perfoxzned more easily.
The looseness between the adjacent disks in cutting can be prevented, for example, by providing a convex and concave on the adjacent faces of disks in advance as shown in Fig. 14, and by fitting the convex to the concave.
In configuring the rotary dwm 2~1a, 29b, the phase of cutting edges on the adjacent disks is shifted in the circumferential direction and the cutting edges a=e arranged discontinuously in the axial direction as shown in Fig. 15;
by which the length of chip can be decreased, so that the damage to cutting edge caused by the entanglement of chips can be avoided.
Fig. 16 shows a rotary drum which is so constructed that a portion near the outer periphery of shaft is made a hollow 32 except for the shaft end in the' interior of the main shaft 23a, 23b, a liquid such as oil is supplied to the hollow . through the supply port 33 , and the pressure in the main shaft 23a, 23b is increased after mounting the clisks i1 ... ii to expand the shaft diameter, by which the disks are fixed firmly to the main shaft. This construction can relax the worlEing accuracy of inside diameter of disk fitted to the main shaft within the range of expansion allowance of main.shaft. If the supply port 33 is closed by a screw 34 after the expansion of main shaft, the expansion of main shaft can be maintained easily.

' 64881-449E
Fig. 17 shows an example i~ which a contracting mechanism is provided such that when there is a possibility of damage to cutting edge caused by the application of an excessive load on the disk in surface cutting of sheets etc. , the pressure in the iaain shaft 23a, 23b is reduced to instantly decrease the shaft diameter.
Figs . 18. (a) and 18 (b) show the principal portion of Fig. 17. The contracting mechanism consists of a striker 35 which is fixed and held on the side of disk and a plug 36 installed on the main shaft. If an ex~..essive load is applied to the disks i1 . . . ii and a slip occurs between the disks i1 .
i; and the main shaft 23a, 23b, the striker 35 installed on the side of disk collides with the plug 36 on the main shaft, so that'the plug 36 comes off. Thereby, the liquid such as oil in the main shaft is discharged; resulting in the contraction of shaft diameter.
Fig. 19 shows an example of rising/lowering pattern of rotary drum (the pattern of only the rotary drum positioned on the upper side of the sheet is shown). Fig. 2O shows a cutting state of a sheet. Figs. 21 (a) and 21 (b) show a wearing state of cutting edge of the rotazy drum in the case where sheet surface cutting was performed by installing 20 disks with a diameter of 900 ~n and a thickness of 100 mm on the main shaft.
The projections on the joined sheet bars (heating temperature : 14 7 0 ° C , pres sing force : 2 kgf /mm2 ) were removed by cutting (circumferential speed of rotary drum: 100 m/s) in accordance with the gattern shown.in Fig. 19 by using a cutting apparatus having rotary drums of the construction shown in Fig. 12 in which 20 disks (made of S55C) with a diameter of 900 mm, a thickness of 100 mm, a cutting edge pitch of 18.84 mm, and the number of cutting edges of 150 were arranged on a main shaf t ( shif t of adj acent cutting edge s 9.42 aun). As a result, it was confirmed that although the time taken for the replacement of the :rotary drum was usually about 48 hours, only about 8 hours are required for the replacement of disks in the present .invention, so that the present invention is advantageous in improving the raork efficiency.
The following is a description of a case where excessive cutting caused by the damage to cutting edge especially by operation error of the cutting apparatus and the excessive pressing against the sheet, which is an object to be cut, is avoided by using the means described in the above items 10 ) and 11 ) .
In an apparatus having a sheet cutting rotary drum such as a milling cutter and grinding wheel , the outside diameter of the drum measured off-line is inputted to a computer by the operator , and the rotary drums are moved vertically based on the inputted information to adjust the position, by which a predetermined pressing amount is given to the cutting edge or grinding stone (specifically, he level of cutting edge or grinding stone face of the rotary drum is made to coincide with the level of sheet surface, that is, so-called zero adjustment is made, and then the rotary drum is moved from this state so as to obtain a predetermined working allowance) . In the state in which the rotary drum is being rotated at a high speed for cutting, the position of cutting edge or grinding stone face of the rotary drum cannot be checked, so.that exact zero adjustment cannot be made . Therefore, the working allowance of sheet exceeds, the allowable range, or inversely the target workingallowance cannot be obtained because the Wear of cutting edge or grinding stone is higher than expected, so that working must be performed again. In particular, if the sheet is broken by the rotary drums because of the error of input to computer by the operator (for example, error of setting of rotary drum diameter) or the failure of a servo valve etc. of the cylinder for vertical movement, the cutting edges or grinding stones of the rotary drum are brought into contact with each other, resulting in an accident of damage to rotary drum.
According to the present invention, the apparatus, in which a sheet a.s passed between a pair of rotary drums rotating in the direction reverse to each other and the top and bottom surfaces thereof is cut continuously or intermittently, is configured so than a disk for recognizing gap between drums having a larger diax~ter than that of the rotary drum is arranged at both ends or at one end of at least one rotary drum. This drum is brought into contact with the disk of the other rotary drum, and zero adjustment is made with this state being a reference. Thereby, the erro~c of working amount caused by excessive pressing of rotary can be decreased greatly. Also, even if there is an input error of disk outside diameter, the load becomes excessive by the contact between disks , so that the input error' can be recognized in the screw down system before the sheet is cut.
In the case where a measuring means (non-contact type distance meter, eddy-current type sensor, etc.) which can find the wear amount (outside diameter of cutting edge on rotary drum) of rotary drum is provided in place of the disk;
even if a wear of cutting edge or grinding stone is produced by the cutting of sheet, the rotary drums can be moved vertically on the line exactly by the wear amount (however, the speed of rotary drum is low). Therefore, more precise working can be performed than following the planned allowance. As the measuring means, an eddy-current type sensor, a laser type distance sensor; etc. can be used. The eddy-current type sensor measures a distance by detecting the current value changing according to the distance between the measuring means and the ferrous cutting edge by using eddy current. The laser type distance sensor measures a distance by detecting a reflected wave of laser beam irradiated on the cutting edge or grinding stone face by using laser beam.
At the outer periphery of rotary drum, cutting edges or grinding stones are arranged in accordance with the sheet to be cut. For example, when scratches or dents of hpt-rolled steel, projections of steel product joint portion, etc. are treated, a milling cutter cutting edge is used. When pushing flaws of cold-rolled steel, oscillation marks of hot-rolled steel, slight dents, etc. are treated; a grinding stone is used:
Fig. 22 shows a configuration of the' cutting apparatus in accordance with the present invention. In this figure, reference numerals 38a and 38b denote rotary drums arranged so as to cut the top and bottom surfaces of the sheet S1, S2 continuously or intermittently by holding the sheet therebetween (a rotary drum pan be used, for example, which is configured so that a plurality of disks having cutting edges at the outer periphery thereof are arranged along the rotating shaft of the drum and the positions of cutting edges on, the adjacent disks are shifted alternately.. ) , 39a and 39b denote disks for recognizing gap between drums shown in the example in which the disk is arranged at both ends of the rotary drum 38a, 38b, 40 denotes a shaft case for containing a bearing rotatably.supporting the rotary drum, 4l denotes a screw down cylinder, 42 denotes a housing; 43 denotes a spindle, 44 denotes a pinion stand, and. 45 denotes an electric motor.
In order to surface-cut a sheet with a predetermined allowance, the disks 39a aad 39b are brought into contact with each other by moving the rotary drums 38a and 38b to find the vertical absolute positions of cutting edges of the rotary dress (Zero adjustment) . Subsequently, the rotary drums 38a and 38b are rotated to a predetermined. speed, and the rotary drums 38a and 38b are moved from that position to the same 64$81-449E
level as that of the top and bottom surfaces of the heet S
(S1, S2) respectively, and then the movement of the rotary drums 38a and 38b is stopped at the point of time when the level such that the predetermined cutting allowance can be obtained is reached. The sheet 1 passing between the pair of rotary drums is .cut by the cutting edge or grinda.ng stone at the outer periphery of the rotary drum. Although there is fear of too large allowance caused, for example, by the setting error of initial position of the rotary drum 38a, 38b, excessive cutting or grinding of sheet can be prevented by bringing the disks 39a and 39b installed at the end of the rotary drums 38a and 38b into contact with each other in the state of maximum cutting allowance.
In the present invention, as shown in Fig. 23, the disk 39a, 39b may be installed only at one end of. the rotary drum 38a, 38b: Also, in place of the disk 39a, 39b, as shown in Figs . 24 and 25 , several measuring means 46 may be arranged along the ax3.al direction of at least one rotary drum.
Fig. 24 shows an example in which the measuring means 46 are arranged on the upside only; while Fig. 25 shows an example in wha.ch the measuring means are arranged on both the upside and downside. It is best that ttte measuring means 46 be .arranged on the upside of the rotary drum, but they may be arranged on both the upside and downside, or they may be arranged on the downside only. The measuring ateans on the downside is required to strictly take waterproof measures when cooling water is used for cutta.ng or grinding and dustproof measures against chips as compared with the measuring means on the upside. By making zero adjustment by grasping the wearing state of cutting edge or grinding stone at the outer periphery of rotary drum using the measuring means 46, excessive cutting or grinding of sheet can be avoided. By disposing a cylinder on the measuring means 46 so that the measuring means can move close to or apart from the rotary drum, an accident of contacting the measuring means 46 with the rotary drum 38a caused when the rotary drum is moved can be prevented. Also; the measuring means 46 may be constructed so as to be capable df moving in the width direction of sheet S.
Fig. 26 shows another example of apparatus in accordance with the present invention.
Although the disk 39;a, 39b, which. is provided only on one side of the rotary drum 38a, 38b, shown in Fa.g. 23, has a larger diamQter than that of the rotary ' drum, the diameter of the disk 39b is equal t:o or smaller than the diameter of the rotary drum 38b. Moreover, when the upper and lower rotary drums are brought close to each other by the screw down cylinders, the disk 39a and the disk 39b come in contact with each other before the rotary drum 38a and the rotary drum 38b come in contact with each other . In the case where the diameter of the disk 39a a.s different from that of the disk 39b, when the upper and lower rotary drums are rotated at the same rotational speed, a difference in circumferential speed occurs on. the aforementioned disks , so that there is a possibility of damage to disk caused by frictional heat generation: Therefore; adjustment including zero adjustment should be made without rotating the drum.
An example of specific procedure for zero adjustment is shown in Fig. 27: The gap between the upper and loner rotary drums is decreased with the command of zero adjustment start, and when a load is applied by hydraulic reduction, screw down is performed to the expected position (40 t load is applied when the disk width is :L50 mm~ . After it is confirmed that the oil column value calculated from the outside diameter of rotary drum agrees with the actual oil column value, the cutting edge is rotated, and it is confirmed that the load deviation caused by disk eccentricity is not larger than ~2t. Thus, zero adjustment is completed.
The wear amount at the tip end of rotary drum 38a, 38b is measured by the measuring means 4 6 as shown i~ Fig . 29 , and the upper rotary drum 38a is xaoved downward and the lower rotary drum 38b is moved upward by the wear amount, by which a constant working amount can always be maintained.
Then the cutting edge or grinding stone wears eccentrically, uniform working sometimes cannot be performed in working sheets with a different width by simply moving the rotary drums up or down. Therefore, the rotary drum is replaced, or the disks subjected to heavy eccentric wear are replaced for the rotary drum which is canfiguxed so that disks having cutting edges etc . at the outer periphery thereof are combined.

" 64881-449E
Such zero adjustment can be made not only on.-line but also off-line. In either case, a trouble caused by input error does not occur.
Next, effective recovery of high-temperature chips produced in sheet surface cutting, which is performed by the means described in the above items 12) and 13), will be described especially far an example of the case where a preceding sheet and a following sheet are joined and hot-rolled continuously.
As shown in Fig. 28, a crop shear 49 is installed on the downstream side of rough rolling mill group 47 between the rough rolling mill group.47 and a (finish rolling mill 48.
The crops at the tail ' edge of preceding sheet $1 and the leading edge of following sheet S2 are cut and removed by the crop shear 49. A joining device 50 is installed on the downstream side of the crop shear 49. The tail edge of preceding sheet S~ and the leading edge of following_sheet S2 are joined to each other by the joining device 50.
Specifically, the joining device 50 is moved at the same speed as the advance speed of preceding sheet:. S1 and following sheet S2 by using a carrier 51, and the leading edge of following sheet S2 i.s clamped by;an input-side clamp 53a in an inner frame 52 and the tail edge of precedi.ngsheet Sl is clamped by an output-side clamp 53b. In this state, the joint portion is heated by a heater 54, which uses eddy current of a high frequency coil, for example. By moving the inner frame 52 .
to the output side, the tail edge of preceding sheet Sl and ' 64881-449E
the leading edge of following sheet S2 are pressed in the advance direction and joined.
A cutting apparatus 55 for removing projections is installed on the downstream side of the joining device 50.
The projections at the joint portion between the tail edge of preceding sheet Sl and the leading edge of following sheet S2 are removed by the apparatus 55. Specifically on the top and bottom surfaces of the joint portion h between the tail edge of preceding sheet Si and the leading edge of folloc~ing sheet SZ , as shown in Fig . 2 9 , proj ections M are produced by the compression caused by press joining. At this projection M, foreign matters Ml such as scale aggregate . If the sheet with the projections -M is rolled into a finish rolled product by the finish rolling mill group 48 , as shown .in Fig: 30 , the foreign matters Ml are extended and remain in the finish rolled product over a long range . If the foreign matters Ml remain in the finish rolled product, the strength of joint portion is remarkably decreased by the foreign matters Ml.
Therefore, the projections at the joint portion are removed by the cutting apparatus 55. The cutting apparatus 55 is provided with a pair of rotary drums 55a and 55b holding a sheet therebetween, and as shown in Fig. 31, the projections M at the j oint portion are cut and removed by the cutting edges 56a and 56b on the rotary drums 55a and 55b. When the projections M of sheet is removed by the cutting, apparatus 55, high-temperature chips scatter at a high speed on the rotation side of cutting edge 56a, 56b (upstream side in the figure) and adhere to the surface of sheet, so that there is fear of degraded quality. On the output side of the cutting apparatus 55, therefore, a chip removing device 57 as shown in Fig. 32 is provided. As shown in Fig. 32, a rotating grinding stone 58 movable in the sheet width direction is provided. The surface of sheet is ground by the rotating grinding stone 58, and chips 59 are scattered in the sheet side direction. On the other hand, a dust collecting hood 60 is provided at the width end of sheet. In the dust collecting hood 60 , water is supplied in a laminar! flow form via a supply pipe 61 and a water tank 62 , so that a water film 63 is formed over the wall surface. The high-temperature chips 59 scattering toward the dust collecting hood 60 in the sheet side direction when the sheet is ground by the rotating grinding stone 58 are trapped by the water film 63, cooled and dropped, and recovered in a pit (not shown) together with water through a drainage channel 64.
Thus, in the continuous hot rolling facility, measures are taken to prevent the high-temperature chips produced when the sheet surface is cut by the cutting apparatus 55 from adhering to the sheet. However, the chip removing device 5?, which disposes chips in the sheet width direction, requires the dust collecting hood 60 having a large wall surface, which is disadvantageous in tezms of space . The cutting apparatus 55 is provided with the rotary drums 55a and 55b on the upside and downside of sheet. For the lower rotary drum 55b, the water film 63 or ~raterdrops _ ~g _ ' 64881-449E
which flaw down cannot be formed. Therefore, the chip removing device 57 is now installed near the upper rotary drum 55a only.
In the present invention, iri particular, the cutting apparatus is configured so that the rotary drums having a width larger than the maximum sheet width are arranged above and below the sheet, the upper rotary drum is supported by a chock 'moved vertically by a screw dawn, cylinder, the lower rotary drum is supported by a chock moved vertically by a height adjusting cylinder, an upper chip discharge means is provided on the chip discharge side of the upper rotary drum, and a lower chip discharge means is provided on the chip discharge side of the lotaer rotary. drum. -Thereupon, the chips produced in sheet surface cutting can be recovered without an increase in facility size. Also, in the present a:nvention, a flowing water injecting means is provided in each of upper chip discharge means and lower chip discharge means, so that the chips can be cooled rapidly, by which the chips can be recovered efficiently.
Fig. 33 is a side view showing the concept of a continuous hot rolling facility. Fig. 34 is a view taken along the line II-II of Fig. 33, and Fig. 35 is a view taken along the line III-III of Fig. 34. In Fig. 33; a crop shear 49 is installed on the downstream side of a rough rolling mill group 47. The crops at the tail edge of preceding sheet S1 and the leading edge of following sheet S2 are cut and removed by the crop shear 49. A joining device 50 is installed on the downstream side of the crop shear 49. The tail edge of preceding sheet Sl and the leading edge of following sheet S2 are j oined to each other by the j oiniaig device 50 . A cutting apparatus 55 is provided between the joining device 50 and a finish rolling mill group 48. The projections at the joint portion h are cut and removed by the apparatus 55.
The cutting apparatus 55 is provided with a pair of rotary drums 65a and 65b holding a sheet therebetween. The rotary drum 65a, 65b is formed with c.-sitting edges 66a, 66b with a width larger than the maximum sheet width of rolled product , at the outer periphery thereof . A roll chock 68 is supported by a housing h of the cutt:Lng apparatus 55 via a screw down cylinder 67 so as to be mavable vertically, and the upper rotary drum 65a a.s rotatably supported by the roll chocks 6$ . Also, a roll chock 70 is supported by the housing h via a height adjusting cylinder 69 so as to be movable vertically, and the lower rotary drum 65b is rotatably supported by the roll chocks 70.
An upper chip discharge duct 71 is provided as an upper chip discharge means near the rear side in the rotating direction of the upper rotary drum 65a. The upper chip discharge duct 71 is formed with an opening 72 which opens on the downside of the rotary drum 65a and is wider than the rotary drum 65a. Flowing water injecting headers 73 :are provided as flowing water injecting means in the upper chip discharge duct 7l, and injection nozzles ?4 of the flowing water injecting headers 73 are arranged so as to face downward. A discharge section 75 is provided in the upper chip discharge duct 71. The discharge section 75 extends from the working side of the rotary drum 65 (left side in Fig. 34) to a drainage channel 76. Chips 77 produced when a sheet is cut by the upper rotary drum 65a are recovered in'the upper chip discharge duct 71 through the opening 72, and discharged into the drainage channel 76 by the injection of flowing water from the flowing water injecting headers 73. A lower chip discharge duct 78 is provided as a lower chip discharge means near the rear side in the rotating direction of the lower rotary drum 65b. The lower chip discharge duct 78 is formed with an opening 79 which opens on the upside of the rotazy drum 65b and is wider than the rotary drum 65b. A flowing water injecting header 79 is provided as a flowing water injecting means a.n the lower.chip discharge duct 78, and an injection nozzle 80 of the flowing water injecting headers 79 is arranged so as to face upward. .A discharge section 81 is provided in the upper chip discharge duct 78. The discharge section 8l opens above the drainage channel 76.
Chips 77 produced when a sheet is cut by the lower rotary drum 65b are collected and recovered in the lower chip discharge duct 78 through the opening 79, and discharged',into the drainage channel 76 by the injection of flowing water from the flowing water injecting header 79.
In the above-described continuous hot rolling facility, the tail edge of preceding sheet S1 and the leading edge of following sheet SZ are joined to each other by the ' 64881-449E
joining device 50, and'the projections M at the joint portion h are cut and removed by the cutting edges 66a and 66b on the rotary drum 65a and 65b of the cutting apparatus 55 (see Fig. 31) .
In the cutting apparatus 55, the height of the top surface of the lower rotary drum 65b is adjusted in advance by the height adjusting cylinder 69; and the upper and lower rotary drums 65a and 65b are rotated in the direction reverse to the advance direction of sheet. In cutting, the rotary drums 65a and 65b are moved close to each other by the screw down .cylinder 67 and the height a<3justing cylinder 69, respectively, by which foreign matters including aggregated scale at the joint portion h are cut and removed together with the projections M on both of the top and bottom surfaces at the same time (see Fig. 31).
The high-temperature chips 77 scattered to the input side at a high speed by the high-speed rotation of rotary drum during the cutting process are recovered in the upper chip discharge duct 75 and the lower chip discharge duct 78, cooled by the water injected from the injection nozzles 79 and 80 of the flowing water injecting headers 73 and 79, and discharged in the drainage channel 76 through the discharge sections 75 and 81. Thereupon, the projections M at the joint portion Z on both the top and bottom surfaces of sheet can be cut and removed at the same time, and there is no possibility of adhesion of high-temperature chips 77 to other equipment etc.

The rotary drums 65a and 65b., which are rotated in the direction reverse to the advance;clirection of sheet in this example, may be rotated in the advance direction.
The following is a description of a case where surface cutting is achieved while a sheet is conveyed stably by preventing deformation of hot sheet, especially downward deformation of leading edge by using the means described in the above item 14).
Fig. 36 is a side view of a sheet surface cutting apparatus. In the apparatus thus configured, like the apparatus shown in Fig. 35, the heights of the rotary drums 82a and 82b are adjusted, the leading edge of preceding sheet Sl is passed through the opposing section of a pair of rotary drums 82a and 82b, and the rotary drums 82a and 82b are moved close to each other while being rotated at a high speed . just before the joint portion with the following sheet S2 reaches the opposing section of the pair of rotary drums 82a .and 82b, by which the projections at the joint portion L of sheet is cut. At this time, the preceding sraeet S1 passing between the pair of rotary drums 82a and 82b is at a temperature of about 800 to 900°C, so that the strength thereof is decreased. .
Therefore, there is a possibility that the leading edge of preceding sheet S1 passing through ain input-side apron 83 hangs down, as indicated by the two-dot chain line in the figure .
Since a fixing apron cannot be installed between the pair of rotary drums 82a and 82b, if the leading edge of following sheet S2 hangs down, it comes in contact with an output-side apron 84 or the cutting edge of lower rotary drum;
so that there is fear of damage. to cutting edge of rotary drum or incapability of passing of sheet.
According to the present invention, in the apparatus for cutting the top and bottom surfaces continuously or intermittently by passing a hot sheet between the pair of rotary drums rotating in the direction reverse to each other, a movable sheet passing guide for holding the hot sheet for the period during which the leading edge of preceding sheet advances from the input side to the oui~put side of the rotazy drum. Until the leading edge of preceding sheet passes between the rotary drums and reaches the output-side apron, the sheet passing guide is inserted between, the input-side apron and the output-side apron to guide the leading edge of preceding sheet by using the sheet passing guide. Therefore, the deformation of sheet, especially of the leading edge thereof, can be prevented, and the incapability of passing of sheet does not occur, so that the joint portion of sheet 2p can be cut to a predetermined depth by setting a predetermined gap between the upper and lower rotary drums before the joint portion between the preceding and following sheets reaches the rotary drum.
Figs. 37 and 38 show a configuration of cutting apparatus in accordance with the present invention. A pair of rotary drums 85a and 85b of the cutt~.ng apparatus is formed with cutting edges 8:6a and 86b with a width larger than the maximum sheet width on the outer peripheral surface . A roll chock 89 is supported by a housing 87 of -the cutting apparatus via a screw down cylinder 88 so as to movable vertically, and the upper rotary drum 85a is rotatably supported by the roll chocks 89. Also, a roll chock 91 is supported by the housing 87 via a height adjusting cylinder 90 so as to be movable vertically, and the lower rotary drum 85b is rotatably supported by the roll chocks 91. The roll chocks 89 and 91 are supported by balance cylinders 92 respectively, so that the heights of the rotary drums 85a and 85b are adjusted. On the sheet pass line, an apron 93, a table roller 94, an input-side apron 95, an output-side apron 96, a table rollex 94, and apron 93 are installed from the upstream side: The preceding sheet S1 is carried from the input-side apron 95 to between the pair of rotary drums 85a and 85b by being guided by the input-side apron 93 and the table roller 94, and carried out by passing through the output-side apron 96 by being guided by the output-side apron 93 and the table roller 94.
As shown in Figs . 37 and 38 , at the lower part of the housing 87 is provided a center shaft 97 extending in parallel With the rotating shafts for the rotary drums 85a and 85b, and the base end of an arm 98 is =otatably supported by the center shaf t 97 . A plurality of rows of arms 98 extending toward the output-side direction are arranged in the axial direction of the rotazy drum 85a, 85b, and a connection plate 99 is mounted at the tip end of the ar_m 98. The connection plate 99 is provided With arcuate sheet passing guides 100.
A plurality of rows of sheet passing guides 100 are arranged in the axial direction of the rotazy drum 85a, 85b . By turni..ng the arms 98 around the center shaft 9'7, the sheet passing guides 100 are attached from or detached to the output side to or from between the pair of rotary drums 85a and 85b between the input-side apron 95 and the output-side apron 96, that is, between the lower rotary drum 85b and the sheet passing plane. A connection plate 101 is installed at the intermediate part of the arm 98 , and an operating rod 103 of a turning cylinder 102 is pivotally mounted to the connection plate 101. Thus, by extending/contracting the operating rod 103 by the drive of the turning cylinder, the arms 98 are turned around the center shaft 97 , so that the sheet passing guides 100 are attached to or detached from between the lower rotary drum 85b and the sheet passing plane.
Before a preceding sheet S1 and a following sheet S2 are joined, the upper and lower rotary drums ,85a and 85b are apart from' each other, and after the preceding sheet Sl and the following sheet S2 are joined; the operating rod 48 is extended by the drive of the turning cylinder 102 before the leading edge of preceding sheet Si reaches the cutting apparatus. By the extension of the operating rod 103, the arms 98 are turned around the center shaft 97, by which the sheet passing guides 100 are inserted between the lower rotary drum 85b and the sheet passing plane from the output direction (the state indicated by the two-dot chain line in Fig. 37) . In this state, the leading edge of preceding sheet S1 advances from the input-side apron~95 to the output-side apron 96 by being guided by the sheet passing guides 100 without dropping. When the leading edge of preceding sheet S1 reaches the output-side table roller 94 and the apron 93 , the operating rod 103 is contracted by the drive of the turning cylinder 102 to return the plate passing guides 100 to the original positions (the state indicated by the solid line in Fig . 37 ) .
After the plate passing guides 100 are returned to the original positions, the heights of rotary drums are adjusted by the adjustments of the screw down cylinder 104 and the height adjusting cylinder 90. Just before the joint portion h of the preceding sheet Si and the following sheet S2 reaches between the rotary drums 85a and 85b, the upper and lower rotary drums are rotated at a high speed in the direction reverse to the sheet advance direction. In cutting, the upper and lower rotary drums 85a and 85b are moved close to each other by the screw down cylinder 104 and the height adjusting cylinder 90, respectively, to cut the top and bottom surfaces at the same time while removing the projections M at the.joint portion Iy.
In this example, the rotary drums 85a and 85b are rotated in the direction reverse to the sheet advance clirection. However, they may be rotated in the sheet advance direction. Also, the sheet passing gu5.des 100 are formed into an arcuate shape, and the sheet passing guides 100 .are ° 64881-449E
attached or detached by turning the arms 98 in this example .
However, plate-shaped sheet passing guides may be attached to or detached from between the rotary drums by being slid.
Thus, in the present invention, movable sheet passing guides 100 are provided between the rotary drum and the sheet passing plane in the cutting apparatus, and the sheet passing guides 100 are inserted between the upper and lower rotary drums to guide the leading edge of preceding sheet S1 when the leading edge of preceding sheet S1 passes between the rotary drums. Therefore, the leading edge of preceding sheet does not come in contact with the output-side apron by high-temperature deformation etc.
In the apparatus having the movable sheet passing guides as shown in Figs . ~ 37 and 38 , the problem of sheet passing caused by the deformation of sheet, especially the leading edge thereof , can be avoided well . During the cutting process of sheet, however, as shown in Fig. 39, when the 'sheet comes in contact with the cutting edges of the rotary drums 105a and 105b, the sheet sometimes is fluttered by the resistance. In such a case, there is fear of incapability of smooth cutting. Also, at the same time, the variation in sheet tension becomes large, which causes a great disturbance in terms of the sheet thickness variation in rolling or the tension control in the sheet joining process or coil box facility. Further, when the sheet flwtters heavily, not only the cutting apparatus is damaged, but also the sheet interferes with the apparatus , by which the sheet surface is damaged, resulting in an adverse effect on the quality. In the pre ent invention, especially as.described in the above item 15), holding rolls or pinch rolls for restraining the tension variation caused by fluttera.ng in the surface cutting of hot-rolled sheet are arranged on at least one of the input side and output side of the rotary drum, by which the damage to the apparatus and the quality deterioration of sheet are prevented.
Fig. 40 shows a basic configuration of an apparatus in accordance with the present invention . This figure shows , as an example, a case where pinch rolls 106a and 106b are installed between table rolls T on the input and output sides of the rotary drums 105a and 105b . P..lso , Fig . 41 shows , as an example, a case where holding rolls 107a and 107b, which c~ ~ ~ved vertically, are arranged just above the respective table rolls T on the input and output sides of the rotary drums 105a and 105b.
In the above-described configuration; a sheet S is held by the pinch rolls 106a and 106b or the holding rolls 107a and 107b locally or in the whale range in the width direction on the input and output sides of the rotary drums 105a and 105b for cutting the sheet S1, S2: Therefore, the fluttering of sheet is decreased greatly, and uniform and smooth cut surface can be obtained. Also; a$ shown in Fig. 42, a stable tension variation is caused by cutting reaction only, so that the feedback on the rolling side can be performed by predicting the tension disturbance, and the ' 64881-449E
resultant sheet thickness variation can be reduced.
Fig. 43 shows a tension variation in the case where the sheet surface is cut by the rotary drums while the sheet is held by the holdimg rolls as shown in Fig. 41. When cutting is performed without holding the sheet; a large tension variation is caused irregularly. Contrarily, When the holding rolls are used, the tension variation is almost constant except for the cutting edge pressing time and retreating time.
The apparatus thus configured can be used for finishing strips, plates and slabs and for finishing sheets at the rough mill, as well as in the ca.>e where the projections at the j oint portion are removed whey a preceding sheet and a following sheet are joined and hot finish rolled continuously. For the specific apparatus, any of Figs: 1, 4, 7, 10, 12 to 18, 22, 23, 24, 35, 37, 40, and 41 can be applied.
INDUSTRIAh APPhICABIhITY
According to the present invention, the following effects can be expected.
1) When hot-rolled steel products having joint portions, especially a preceding sheet and a following sheet, etc. are surface-cut by using a milling cutter, the cutting resistance is controlled by the adjustment of cut depth, and the tension caused on the sheet by the cutting resistance is reduced to a value lower than the breaking strength of joint portion, by which the breakage is prevented. Therefore, the ..
production efficiency in the subsequent hot rolling process can be improved (claims 1 to 4).
2) Stable' surface cutting can be performed for a long period of time, so that the cutting efficiency can be enhanced remarkably (claim 5) ..
3) Since the rotary drum is configured by using a plurality of disks having cutting edges at the whole outer periphery, the rotazy drum can be mounted and disauounted easily, so that he work efficiency can be improved. Also, only the disks in the range where wear proceeds and tree life has been expired may be replaced, so that the cost of rotary drum can be reduced. Since the disks are fixed and held by expanding the main shaft, the disks can be mounted easily, and also the tolerance of fitting of the disks to the main shaft need not be set especially strictly, so that the disk design conditions can be relaxed. When the phase of cutting edges on the adjacent disks is shifted in the circumferential direction, and the cutting edges are arranged discontinuously in the axial direction, the length of chip produced by the sheet surface cutting can be decreased, so that there is no possibility of damage to cutting edges caused by the entanglement of chips . Further, only the rotary drum can be rotated by contracting the diameter of main shaft just when an excessive force is applied to the rotary drum, so that the damage to cutting edges or seizure of the main shaft and rotary drum does not occur (claims 6 to 9).
4) The absolute position of cutting Edge or grinding stone - '' 64881-449E
r can be detected only by vertically moving the rotary and bringing the disks into contact with each other, so that zero adjustment can be made easily, and hot-rolled steel products can always be cut in the allowable range (a predetermined cutting allowance) , by which the sheets of stable quality can be supplied for ~, long period of time-Also, the cutting edges or grinding stones installed at the outer periphery of the rotary drum are not brought into contact with each other, so that the damage to the cutting edge or grinding stone can be prevented. In particular, by using a measuring means, the wear state (wear deviata.on) of cutting edge or grinding stone in the direction along the rotary drum can be detected, and the .replacement of cutting edge etc . following the increase in deviation by wear carp be performed automatically, so that labor saving can be achieved (claims 10 and 11).
5) The rotary drums having a width larger than the maximum sheet width are arranged above and below the hot-rolled steel product between the joining device and the finish rolling mill group, the upper rotary drum is supported.by the chocks moved vertically by the screw down cylinder, the lower rotary drum is supported by the chocks moved vertically by the height adjusting cylinder, the upper chip discharge means having the flowing water injecting means is provided on the chip discharge side of the upper rotary drum, and the lower chip discharge means having the flowing water injecting means is provided on the chip discharge side of the lower rotary drum.

Therefore; by moving the rotating cutting edges close to each other via the chocks by using the screw down cylinder and the height adjusting cylinder while rotating the rotary drums at a high peed, the projections between the tail edge of preceding hot-rolled steel product and the leading edge of following hot-rolled steel product jointed by the joining device is cut and removed by the pair of upper and lower rotary drums, and the chips scattered in the rotating direction by the high-speed rotation of rotary drums are accommodated in the upper and lower chip discharge means. The chips are cooled and allowed to flow down by the flowing water injected from the flowing water injecting means , and discharged. As a result, the projections on the top and bottom surfaces at the joint portion are removed at the same time by a continuous operation matching the advance of the steel product, and the adhesion of high-temperature chips to other equipment can be prevented.
6) In the case where continuous rolling is performed by installing the joining device for joining the tail edge of prececling hot-rolled steel product to the leading edge of following hot-rolled steel product between the rough rolling mill group and the finish rolling mill group, the rotary drums having a width larger than the maximum, sheet width of rolled product are arranged above and belpw the steel product between the joining device and the finish rolling mill group, and the sheet passing guides are installed detachably between the lower rotary drum and the sheet passing plane for the steel product, so that the sheet passing guides are inserted between the upper and lower rotary druids when the preceding steel product passes between the rotary drums, and the leacling edge of preceding steel product is passed to the output side by being guided by the sheet passing guides.
After the leading edge thereof reache:~ the output side, the sheet passing guides are removed from between the upper and lower rotary drums , and before the j oint portion between the preceding steel product and following steel product reaches the rotary drums , the upper and lower rotary drums are rotated and moved close to each other, by which the joint portion can be cut to a predetermined depth: As a result, the leading edge of preceding steel product can be prevented from hanging down or contacting with the apron etc . , and the incapability of sheet passing can be elimi=iated co~letely.
7 ) The holding rolls or pinch .rolls are installed on the input or output side of rotary drum to hold the sheet in cutting, by which the fluttering of steel product occurring in cutting the sheet is eliminated, and uniform and smooth cut surface can be obtained. Moreover, a tension variation is caused by cutting reaction only, so that the feedback in the rolling process can be performed by predicting the tension disturbance, by which the sheet thickness variation can be reduced. Also, since the fluttering of steel product does not occur, the flaws on the surface and the damage to the facility can be prevented.

Claims

CLAIMS:

1. A surface cutting apparatus for hot-rolled steel products that cuts top and bottom surfaces of a hot-rolled steel product continuously or intermittently by passing said steel product in a sheet passing plane between a pair of rotary cutting drums rotating in a direction reverse to each other, said apparatus having a movable sheet passing guide that is supported to be selectively movable and insertable between a lower one of the pair of rotary cutting drums and the sheet passing plane before a leading edge of the hot-rolled steel product reaches the pair of rotary cutting drums to hold the hot-rolled steel product during a period of time when the leading edge of the steel product advances from an input side to an output side of the rotary cutting drum pair.