Patent Publication Number: US-2018029099-A1

Title: Winding/unwinding device and method for winding/unwinding a metal product in a rolling line

Description:
FIELD OF THE INVENTION 
     The present invention concerns a device and a method for winding/unwinding a semi-worked metal product, for example a flat rolled product exiting from a roughing train, in a rolling line, in particular but not only for flat products such as strip, thin strip or sheet. 
     In particular the invention concerns a winding/unwinding device, interposed between a roughing train and a finishing train, which can be used both in discontinuous or semi-endless mode, to wind the flat product exiting from the roughing train and then to unwind it so as to feed it to the finishing train, and also in continuous or endless mode, with the flat rolled product passing through the device without interruptions. 
     The invention is applied on flat rolled products which can have a thickness of less than 30 mm, advantageously comprised between 10 and 30 mm. 
     BACKGROUND OF THE INVENTION 
     In rolling lines for strip and sheet, it is known to provide winding/unwinding units, possibly associated with a heating furnace, the function of which is to wind a semi-worked product, for example a slab, exiting from a working step, and then to unwind it to feed it to a subsequent process. 
     U.S. Pat. No. 5,335,713 describes for example a winding/unwinding device disposed at exit from a continuous casting. The device comprises two reeling stations disposed inside a furnace, which alternately exchange positions so as to be disposed selectively in a first position for winding a slab exiting from the continuous casting, and a second position to feed the slab to a rolling train. The reeling stations each comprise a rotary mandrel on which the slab winds/unwinds. 
     The device does not provide a passage system which can exclude its functioning in the event that it is desired to make the slab pass without proceeding to winding/unwinding. Moreover, the device does not provide auxiliary means that intervene to facilitate the unwinding of the reel when unwinding is started, thus limiting the use of this solution to determinate thicknesses. 
     Another disadvantage of the device is that at least one end of the reel is blocked outside the heating furnace, so that it is subjected to an unwanted lowering of the temperature. 
     The purpose of the invention is to solve the above problems, achieving a device which, functioning in semi-endless mode, allows to selectively wind a complete slab exiting from a roughing train and then unwind it so as to feed it to a finishing train, but which can easily and quickly be configured to function in endless mode, with the continuous passage of the roughed slab from the roughing train to the finishing train. 
     Another purpose of the invention is to reduce the cycle times required to complete the operations to wind a reel onto a first drum, to unwind the reel from a second drum and to reposition the drums in order to start a new winding cycle of a new reel. 
     The Applicant has devised, tested and embodied the present invention to overcome these shortcomings of the state of the art and to obtain these and other advantages as shown hereafter. 
     SUMMARY OF THE INVENTION 
     The present invention is set forth and characterized in the independent claims, while the dependent claims describe other innovative characteristics of the invention. 
     According to the present invention, a winding/unwinding device for semi-worked flat rolled products is disposed between two rolling units, for example a roughing unit and a finishing unit, located respectively upstream and downstream of the device. 
     The function of the winding/unwinding device, in semi-endless mode, is to wind in the form of reel or roll a length of complete slab exiting from a first rolling process, and then to unwind it so as to feed it to a subsequent rolling process downstream. 
     The slab roughed in the first rolling process is also called transfer bar. 
     According to a characteristic feature of the present invention, the winding/unwinding device consists of a heating furnace and a support structure disposed outside the heating furnace, wherein two winding/unwinding drums are mounted on the support structure, in a substantially diametrically opposite position, positioned inside the furnace, and wherein the support structure, outside the furnace, is selectively rotating so as to dispose alternately a first of the two drums in its winding position or in its unwinding position, the second of the two drums consequently assuming the opposite unwinding/winding position. 
     According to another characteristic feature of the present invention, the two winding/unwinding drums are mounted on the support structure so that they are able to assume an inactive position not interfering with the pass-line of the flat rolled product; the device according to the invention also has support and sliding means, able to be selectively activated at least when the drums assume their inactive position, so as to define a pass-line for the flat rolled product in the event that the activation of the winding/unwinding drums is not required. 
     This can happen, to give a non-restrictive example, if the rolling line is at least temporarily configurable for a so-called endless functioning, that is, without interruptions between casting and rolling. 
     According to another solution of the invention, the device comprises an extraction unit, able to be selectively activated, suitable to cooperate with the leading end of the full reel at least at the start of the unwinding cycle, in order to promote the operations to start unwinding and accompanying the first segment of transfer bar toward the drawing and guide elements toward the rolling unit disposed downstream. 
     The two drums each have at least an eyelet to introduce the leading end of the flat rolled product at the start of winding, so that the leading end can be gripped, for a desired segment, stably inside the drum, thus promoting both the start of the winding operation and also the correct tensing and stable maintenance of the reel, also in the wound condition. 
     According to one solution of the invention, the flat rolled product is wound, after the leading end has been attached while the drum is stationary, at least partly during the step when a first drum is moved from the winding position to the unwinding position, with the simultaneous positioning of the other drum from the unwinding position to the winding position. In particular, in one embodiment of the invention, the movement from the winding position (inlet side) to the unwinding position (exit side) of the winding drum begins not before the unwinding of the reel on the other drum has terminated. 
     In practice, in this embodiment of the invention, there is only one unwinding position, whereas the winding position passes from the initial one, where the leading end of the transfer bar enters the eyelet of the drum, to a series of subsequent intermediate positions, and then moves to coincide with the unwinding position. 
     The possibility of moving the drum from the winding position to the unwinding position during the winding of the rolled product considerably reduces the cycle times. Indeed, when the winding of the reel terminates, the full drum is already in the position suitable for the unwinding of the product toward the downstream, whereas the empty drum is already in the position suitable to receive a new rolled product arriving from the equipment upstream. 
     The reduction in the cycle time allows to use the winding/unwinding device according to the invention even when the distance between the tail end of a first transfer bar and the leading end of a subsequent second transfer bar is very limited. 
     The device can therefore be used effectively and with great productivity in plants of the rapid type, or when it is desired to keep the winding speed as constant as possible. 
     The use of a constant winding speed is extremely important when the device is installed immediately downstream of a heating furnace, since it determines a constant passage time of the bar through the furnace, and therefore a more uniform temperature of the material and consequently a greater ease in rolling. 
     A constant winding speed is also important in applications different than those using a heating furnace upstream the winding/unwinding device, for example in cooling treatments, (e.g. after the casting), or in pickling or other chemical processes. 
     The uniform temperature over the length of the material is also guaranteed by the fact that, with the device according to the invention, the material is completely wound onto the drum, including its tail end, which means that the entire transfer bar is located inside the furnace, so that the tail end of the transfer bar does not go cool. 
     In another variant of the invention, there may not be a single unwinding position either. In fact, the movement of the two drums to exchange position may take place before the unwinding is totally completed. In this way, the empty drum may be prepared for a new winding cycle in a shorter time, since the space that the empty drum has to travel from the moment the unwinding ends to the moment the new winding starts is reduced. 
     Therefore, in a preferred solution, the winding step is completed with the drum already positioned in the unwinding position. 
     According to a possible form of embodiment of the invention, in the final winding step of the reel the extraction unit can be used to accompany and guide the tail end of the reel being wound. The tail end of the reel being wound therefore becomes the leading end of the reel in the subsequent unwinding step. 
     According to a variant of the invention, the unwinding operation is performed at a speed greater than the winding speed, which allows to free the mandrel more quickly and to take it to the winding position before completing the winding onto the other mandrel; in this way it is possible to manage subsequent transfer bars that have a reduced phase difference time between them. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other characteristics of the present invention will become apparent from the following description of a preferential form of embodiment, given as a non-restrictive example with reference to the attached drawings wherein: 
         FIG. 1  is a view of the overall lay-out of a rolling line in which the device according to the present invention is applied; 
         FIG. 2  is a view in section of the device for winding/unwinding a metal product according to the invention; 
         FIGS. 3-9  show in sequence the various positions that the various components of the winding/unwinding device according to the invention can assume, in relation to the step of the cycle in progress; 
         FIG. 10  shows an enlarged detail of an extraction unit; 
         FIGS. 11-12  show two positions that the components of the extraction unit in  FIG. 10  can assume. 
     
    
    
     DETAILED DESCRIPTION OF A PREFERENTIAL FORM OF EMBODIMENT 
     With reference to the attached drawings, the number  10  denotes in its entirety a device for winding/unwinding a semi-worked flat rolled product  20  in an intermediate step of a rolling process for strip or sheet. 
     The device  10 , with reference to  FIG. 1 , is inserted in a rolling line  100  comprising a continuous casting device (not shown) for conventional slabs or thin slabs, a roughing rolling unit  102 , a shears  103  to obtain in semi-endless mode lengths of slab of the desired size, a heating and equalization furnace  104 , the device  10 , an extraction unit  25 , a finishing rolling train  105 , pinch-roll type drawing devices  106  and conventional cooling and winding devices for the strip (not shown). 
     With reference to  FIGS. 3 to 9 , the device  10  comprises, as essential elements, a furnace  11  equipped with an inlet door  12  and an exit door  13 , selectively movable depending on the step of the winding/unwinding cycle in progress. The furnace  11 , provided in known manner with a chimney  14  to discharge the fumes, defines a heated internal volume  15  which houses two motorized winding drums or mandrels, respectively  18   a  and  18   b.  The drums are mounted on a support structure  16 , outside the furnace  11 , in this case conformed as a rotating disc  17 .  FIG. 2  shows the support structure  16  comprising two rotating discs  17  to which are attached the respective ends of the drums  18   a  and  18   b.    
     In order to minimize heat losses and to allow the drums  18   a,    18   b  to rotate, the furnace  11  comprises covers  40  that are made to rotate together with the discs  17 . 
     The discs  17  each comprise a wheel with stakes  41  which engages on respective movement devices  42 . Each movement device  42  of the support structure  16  comprises a motor  43  and a reduction unit  44 . 
     The two reduction units  44  are synchronized mechanically by means of a transmission shaft  45 , which provides to transfer the torque to the wheel with stakes  41 . 
     The motors  43  of the movement device  42  must be synchronized electrically so that they both provide at the same moment the same torque and the same speed of rotation. 
     Motor elements  51  are mounted directly on the discs  17  and provide to move the two drums  18   a  and  18   b.    
     In the solution shown in  FIG. 3 , to give a non-restrictive example, the centers of the motorized drums  18   a,    18   b  are disposed along a diameter  19  of the rotary disc  17  in a diametrically opposite position; when the diameter  19  joining the centers of the drums  18   a,    18   b  is disposed horizontal, it lies in this case in a position of non-interference and above the pass-line of the flat rolled product  20 , for the reasons discussed in detail hereafter. 
     The device  10  also comprises an inlet table  21  and an exit table  22 , selectively movable with respect to the rotary disc  17 , and hence to the drums  18   a,    18   b,  in relation to the different functions that they have to perform as the winding/unwinding cycle progresses. 
     The inlet table  21  comprises a first inlet segment, or feeding table,  23 , with a flat surface, the function of which is substantially to guide the leading end of the rolled product  20  into an introduction eyelet  30  with which the drums  18   a,    18   b  are provided, and a second segment, or entry table,  26 , substantially mobile, on whose surface a plurality of rolls may be present. The exit table  22  is also selectively mobile, and may also have rolls  28  ( FIG. 9 ) which define its upper surface. As an alternative to the rolls  28 , according to another form of embodiment, sliding guides may be present, both on the inlet table  21  and the exit table  22 . 
     On the exit table  22  there is in any case present in the initial part a big motorized roll  27  or snubber roll, which is used during the final winding step and/or during the unwinding of the transfer bar  20 . 
     The device  10  also comprises an extractor element  24 , disposed on the exit side of the furnace  11  and able to be selectively activated to help to open the reel at the start of the unwinding step. 
     Upstream and downstream of the device  10  there are drawing devices of a known type, for example pinch rolls  106  or suchlike. 
     An extraction/straightening unit  25  is provided in the case shown here, downstream of the device  10 , in order to perform one or both of the following functions:
         to straighten the tail end of the transfer bar  20  (which constitutes the leading end in the winding step) bent in the start of winding step when it is introduced into the eyelet  30  of the drum  18   a - 18   b;      to remove the curvature of the transfer bar  20  when its own weight and the low mechanical characteristics due to the high temperatures are not sufficient to keep the leading end of the transfer bar  20  low.       

     In fact, if the leading end were high there would be a risk of jamming in the machine downstream during the entry step. 
     In order to minimize these problems, the extraction/straightening unit  25  comprises a conveyor  39 , which facilitates the correct insertion of the transfer bar  20  into the extraction/straightening unit  25  ( FIG. 7 ). 
     With reference to  FIGS. 3-9 , we shall now describe the operating steps of the winding/unwinding cycles in which the device  10  is used. 
     In  FIG. 3 , the leading end of the transfer bar  20  is guided inside the eyelet  30  of the drum  18   a,  disposed in the winding position. The inlet door  12  of the furnace  11  is obviously open, whereas the exit door  13  is closed so as to reduce to a minimum the losses of temperature from inside the furnace  11 . 
     The drum  18   b  is in the diametrically opposite position and at the start of the casting cycle has no reel to unwind. The leading end of the transfer bar  20  is introduced for a desired segment with the drum  18   a  stationary, then the drum  18   a,  driven by the motor, starts to rotate on its own axis so as to start winding the first transfer bar  20 . 
     The first segment  23  of the inlet table  21  is still up to support the head of the bar  20 , while the second segment  26  is moved down. After few coils being wound on the drum  18   a,  also the first segment  23  of the inlet table  21  is moved down. 
     After having reached a certain diameter of the reel  29  on the drum  18   a  stationary in position ( FIG. 4 ), for example  45  wraps, the disc  17  also starts to rotate ( FIG. 5 ), so that the two drums  18   a,    18   b  start to invert their respective positions, the drum  18   a  continuing to rotate on its axis to continue and complete the winding of the reel  29 , the opposite drum  18   b  moving progressively toward the winding position. 
     When the reel  29  approaches the final winding step ( FIG. 6 ), and more particularly when the tail end of the transfer bar  20  exits from the pinch roll  106  upstream, so that the drawing is lost, the following operations occur, substantially simultaneously:
         the exit door  13  of the furnace  11  opens;   the exit table  22  is raised so that the snubber roll  27  goes into contact with the reel  29 ;   also the first segment  23  of the inlet table  21  is raised in a high position, in order to protect the drum and to support the tail of the transfer-bar  20 ; then, when the drum  18   b  has reached the winding position, the first segment  23  is moved in the winding position so as to allow the head of the transfer-bar  20  to be fed in the drum;   the extraction unit  24  is driven.       

     The extraction unit  24  comprises an actuator  32  suitable to drive a rod  31  at the end of which a presser/extractor device  33  is mounted. 
     More particularly, the presser/extractor device  33  consists of a frame  34 , substantially triangular in shape, on a first top of which an idle presser roll  35  is mounted, on a second top of which an extractor element  36  is mounted, conformed substantially as a hook. 
     With reference to  FIG. 10 , it can be seen how the frame  34  is free to rotate around the pin  37 . The frame  34  is balanced so that its mass barycenter is disposed so as to return it to the inactive position, with the presser roll  35  located forward with respect to the extractor element  36 . 
     An abutment element  48 , located substantially as an extension of the rod  31 , upstream of the frame  34 , and a striker element  49 , attached on the frame  34 , limit its spontaneous rotation in one direction. 
     It is possible, in some steps, with a clamping element  46  driven by a relative hydraulic cylinder  47 , to keep the frame  34  in the inactive position as above, preventing it from rotating in the other direction. This condition is necessary when the presser roll  35  is thrust against the surface of the reel  29 , as shown in  FIG. 11 . 
     The moment the reel  29  begins unwinding, the clamping element  46  is retracted by means of the hydraulic cylinder  47  ( FIG. 12 ). 
     The frame  34 , due to the effect of the pressure exerted by the reel  29  on the presser roll  35 , rotates around the pin  37  and takes the extractor element  36  into contact with the surface of the reel  29 . 
     In particular, in the first step when the extraction unit  24  is driven ( FIG. 6 ), the presser/extractor device  33 , by means of the actuator  32 , is made to advance until it takes the presser roll  35  into contact with the reel  29 , so that the last segment of the transfer bar  20 , that is, the tail end of the reel  29 , adheres to the last spirals already wound. 
     In this step, the winding of a new transfer bar  20  has already started on the free drum  18   b,  disposed in the winding position, substantially without any downtimes. 
     The winding step onto the drum  18   a  terminates with the tail end of the reel  29  positioned between the presser roll  35  and the snubber roll  27 . 
     When the unwinding of the completed reel  29  from the drum  18   a  has to be started ( FIG. 7 ), and before the drum  18   a  starts to rotate in the unwinding direction, the clamping element  46  is retracted so that the extractor element  36 , rotating, spontaneously moves into contact with the surface of the reel  29 , facilitating the unrolling thereof (see in particular the enlarged detail of  FIG. 10 ). 
     Furthermore, below the presser/extractor device  33 , the extractor element  24  also has a shaped profile  38  which, in cooperation with the extractor element  36 , creates a path to guide the leading end of the transfer bar  20  unrolling from the reel  29  and inserts it in the inlet of the extraction/straightening device  25 . 
     As soon as the transfer bar  20  is gripped by the extraction/straightening device  25 , the extraction unit  24  retreats, and the exit door  13  of the furnace  11  closes, even if not completely, leaving only the space necessary for the reel  29  to unroll ( FIG. 8 ). 
     According to a variant not shown here, during the unwinding step, the drum  18   b  is progressively moved towards an intermediate position between the unwinding position and the winding position, and the drum  18   a  is positioned at the same time in an intermediate position between the winding position and the unwinding position. 
     In this position, the exit table  22  may be positioned in a raised position to support the transfer-bar during the unwinding. 
     This variant allows to reduce the cycle times, since the unwinding operation is performed by moving progressively the full drum towards its position of winding of a new reel, thus providing an empty drum for a new winding cycle in a shorter time. 
       FIG. 9  shows the case where the transfer bar  20  passes through the winding/unwinding device  10  without any intervention by the latter, this solution being provided when the rolling line  100  is functioning in endless mode. 
     As said, in this case the two drums  18   a,    18   b  are disposed with the respective centers lying on a substantially horizontal plane and above the pass-line of the transfer bar  20 . 
     To allow the bar  20  to pass, both the inlet table  21 , with its two elements  23  and  26 , and also the exit table  22 , are taken to the operating position so that the bar  20  can be made to transit on the rolls  28 , if present, on the second segment  26  of the inlet table  23  and on the exit table  22 , so as to guide it toward the extraction/straightening device  25 . 
     Advantageously, in endless mode the passage of the transfer bar  20  from the roughing unit  102  to the finishing unit  105  does not entail any losses in temperature in passing through the winding/unwinding device  10 , since the furnace  11  remains active and keeps the transfer bar  20  at a temperature suitable for the subsequent finishing rolling. 
     Modifications and variants may be made to the device and method for winding/unwinding a rolled product as described heretofore, all coming within the field of protection as defined by the attached claims.