Abstract:
The invention relates to a measuring device, a roll stand and a method for detecting the height of a roll gap between two working rolls in the roll stand. In order to ensure a high level of measurement accuracy of the roll gap transmitter even in the case of horizontal displacement of the working rolls in or against the rolling direction it is proposed in accordance with the invention to carry out adjusting the movement of the roll gap transmitter ( 110 ) with respect to the working rolls in the case of a displacement in or against the rolling direction so that even in a new or displaced end position of the working rolls a suitable relative position, which is required for a high level of measurement accuracy, between roll gap transmitter and the working rolls is guaranteed.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The invention relates to a measuring device with a roll gap transmitter for direct detection of the height or the size of a roll gap between two working rolls in a roll stand. The invention additionally relates to the associated roll stand and a corresponding method. 
         [0003]    2. Description of the Prior Art 
         [0004]    A measuring device for detecting the gap of a working roll pair as an actual value for a regulator for keeping the height of the roll gap between the working rolls constant is known from German Patent Specification DE 24 04 763 C2. The measuring device comprises a measuring head which is aligned in the roll gap with the help of a scissor lever pair biased with the assistance of tension springs. The measuring head is held at the roll stand by way of a pivotable linkage. The measuring head comprises two electromagnetic measuring systems, which each detect the spacing of the individual reference plane from the associated shaft projection acting as a magnet. Through the pivotable linkage, which is dimensioned to be substantially longer by comparison with the height of the measuring head, it is ensured that uniform vertical movements of the working rolls such as, for example, vibrations are virtually without influence on the measurement result, because the spacing of each reference plane of the electromagnetic measuring systems from the associated shaft projection can be kept constant by the measuring device. 
         [0005]    It is disadvantageous with this prior art that the pivotable linkage is merely designed to cause the measuring device or the measuring head to track a vertical movement of the working rolls in order to keep the spacing between measuring head and shaft projection of the working rolls constant. Problems with a horizontal movement of the working rolls in or against the rolling direction are not discussed. 
         [0006]    U.S. Pat. No. 2,032,584 discloses a roll gap transmitter for detecting the height of the roll gap between two working rolls for a manual operation. It is not coupled with the roll stand and therefore cannot be used in any desired position of the working roll pair. 
         [0007]    Finally British Patent Application GB 886 238 discloses a measuring device for measuring the size of the roll gap between two working rolls. The measuring device comprises two measuring rolls which are mounted by a common mount and are brought into contact with the surface of the working rolls for measurement of the size of the roll gap. The measuring rolls are biased by way of a linkage and a compression spring in the direction of the rolling gap plane which is spanned by the two longitudinal axes of the working rolls. The biasing represents a working point of the compression spring. Any change in the size of the roll gap, i.e. any vertical movement of the working rolls relative to one another, leads to a change in the spring force with respect to the working point. This change in the spring force, which represents a change in the size of the roll gap, is displayed on a display device. 
         [0008]    The measuring device according to the British patent application serves, as stated, for detecting vertical movements of the working rolls relative to one another, i.e. a change in size of the roll gap with unchanged horizontal position of the working rolls. A displacement of the working rolls in or against the rolling direction would have the consequence of displacement of the working point of the spring and thus an increasing level of measurement inaccuracy. Starting from this prior art the invention has the object of developing a known measuring device as well as a known roll stand with the measuring device in such a way that the measuring device still supplies satisfactorily usable measurement results, without losses in measurement accuracy, even in the case of displacement of the working rolls in or against the rolling direction. 
       SUMMARY OF THE INVENTION 
       [0009]    This object is fulfilled by the subject of claim  1 . According to that the measuring device comprises a roll gap transmitter for detecting the height of a roll gap between two working rolls in a roll stand in a suitable relative position of the roll gap transmitter with respect to the working rolls, an initialization device for detection of a displacement of the working rolls in or against the rolling direction from a starting position to an end position and a roll gap transmitter displacing device for displacing the roll gap transmitter in dependence on the displacement, which is detected by the initialization device, of the working rolls in or against the rolling direction into the relative position, which is suitable for detection of the height of the rolling gap, with respect to the working rolls in the end position. 
         [0010]    The term “roll gap transmitter” means, in the case of the present invention, a roll gap transmitter for direct detection of the height or size of the roll gap, i.e. the roll gap transmitter is constructed for direct introduction into the roll gap or between the roll pins or the Lynette seats of the rolls. 
         [0011]    The term “displacement of the working rolls” is to be understood in the case of the present invention in the sense of a displacement vector, i.e. it denotes an amount and a direction. 
         [0012]    The term “suitable relative position of the roll gap transmitter with respect to the working rolls” designates, in particular, a suitable spacing between a measuring head of the roll gap transmitter with respect to the surface of the working rolls or the Lynette seat thereof for detection, which is as accurate as possible, of the position of an individual working roll or for detection of the spacing of two working rolls from one another. Only maintenance of the correct/suitable relative position ensures a desired high level of measuring accuracy. 
         [0013]    With the help of the initialization device which is provided in accordance with the invention and which is constructed to detect displacement of the working rolls in or against the rolling direction it is possible, in the case of a displacement of the working rolls in or against the rolling direction from an initial position to an end position, to cause the roll gap transmitter to track the working rolls in the end position so that even in the end position a suitable relative position between the roll gap transmitter and the working rolls and thus a requisite high level of measurement accuracy are guaranteed. 
         [0014]    According to first embodiment the initialization device is constructed in the form of a mechanical coupling point, a scanning head or an optical, electronic or magnetic sensor for detection of a change in the position of at least one of those elements of the mounting of the working rolls which in the case of a displacement in or against the rolling direction are conjunctively displaced. By contrast with a rigid fixing of the roll gap transmitter at the roll stand, the provision of the initialization device and the operative connection thereof with the conjunctively displaced parts of the mounting enable optimum detection of the displacement of the working rolls in or against the rolling direction. 
         [0015]    The parts, which are conjunctively displaced in or against the rolling direction, of the mounting of the working rolls are the part, which is at the roll side, of a horizontal shifting (HS) displacing device, an intermediate plate, a bending cassette or the chock, i.e. the bearing housing of the working rolls in the roll stand. 
         [0016]    In cases in which the initialization device is constructed in the form of a scanning head or one of the mechanical coupling points, thus stands in direct contact with the co-displaced parts of the mounting, the roll gap transmitter displacing device is preferably constructed in the form of a mechanical linkage for direct synchronous transmission of the displacement movement of the conjunctively displaced parts of the mounting of the working roll to the roll gap transmitter. In this embodiment there is usually no requirement for an additional drive for causing adjusting movement of the roll gap transmitter with respect to the working rolls because the displacing work for the roll gap transmitter can in this case be conjunctively exerted by the HS displacing device for the working rolls. 
         [0017]    The linkage can be constructed to be pivotable by way of coupling points. 
         [0018]    Alternatively, the mechanical coupling point in the linkage can, however, also be constructed together as a rigid connection between one of the conjunctively displaced parts of the mounting of the working rolls and the roll gap transmitter. 
         [0019]    Alternatively to a direct transmission of the displacing movements of individual ones of the conjunctively displaced parts of the mounting to the working rolls via a mechanical linkage this transmission can also be carried out contactlessly, preferably if the initialization device is constructed in the form of an optical, electrical or magnetic sensor and an optical or electrical transmission channel is provided for transmission of the measurement signals of the initialization device, which represent the displacement of the working rolls in or against the rolling direction, to a controlling and drive device for displacement of the roll gap transmitter. 
         [0020]    The above-mentioned object of the invention is additionally fulfilled by a roll stand with the claimed measuring device. The advantages of this solution substantially correspond with the advantages mentioned above with respect to the claimed measuring device. 
         [0021]    In addition, it may be mentioned that the roll stand can also comprise, apart from the HS displacing device for displacing the working rolls in or against the rolling direction, an axial displacing device for axial displacement of the working rolls. A conjunctive displacement of the roll gap transmitter in axial direction together with the working rolls is not provided in accordance with the invention because in the case of an axial displacement of the working rolls the relative position required for detection of the roll gap, i.e. the spacing between the roll gap transmitter and the surface of the working rolls or the surface of the Lynette seat thereof, does not change, particularly if the Lynette seat has a constant diameter. 
         [0022]    Finally it is advantageous if the roll gap transmitter displacing device has an operating mode for retraction of the roll gap transmitter into a rest or retracted position outside the roll gap and preferably also outside the roll stand. 
         [0023]    The above-mentioned object is finally also fulfilled by a method for measuring the height of the roll gap. The advantages of this method also correspond with the above advantages discussed with respect to the measuring device.* 
         [0024]    The novel features of the present invention, which are considered as characteristic for the invention, are set forth in the appended claims. The invention itself, however, both as to its construction and its mode of operation, together with additional advantages and objects thereof, will be best understood from the following detailed description of preferred embodiments of a rotor/rotor shaft connection, when read with reference to the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0025]    The drawings show: 
           [0026]      FIG. 1  shows an embodiment of a measuring device according to the present invention in a cross-section; 
           [0027]      FIG. 2  shows the measuring device according to the invention in a plan view; 
           [0028]      FIG. 3  shows the mounting of a working roll with different details; 
           [0029]      FIG. 4  shows the arrangement of the measuring device according to the invention in a roll stand in the case of axial displacement of the working rolls; 
           [0030]      FIG. 5  shows the measuring device according to the invention in cross-section with a controlling and drive device for displacing the roll gap transmitter; 
           [0031]      FIG. 6  shows a roll stand according to the prior art with an arrangement of the roll gap transmitter at the Lynette seats of the working rolls; 
           [0032]      FIG. 7   a - e  show different forms of embodiment for roll gap transmitters and for the arrangement thereof relative to the working rolls in accordance with the prior art; and; 
           [0033]      FIG. 8   a - c  show different examples for an HS displacement of the working rolls with respect to the stand plane according to the prior art. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0034]    The invention is described in detail in the following with reference to the mentioned  FIGS. 1 to 5 . However, the prior art, on which the invention is based, is described beforehand with reference to  FIGS. 6 to 8 . 
         [0035]      FIG. 6  shows a roll stand of the prior art with two backing rolls  240 - 1 ,  240 - 2  between which two working rolls  210 - 1 ,  210 - 2  are mounted. The spacing between the two working rolls defines a roll gap through which rolling stock (not shown here) is moved in rolling direction. Roll gap transmitters  110  for detection of the height of the roll gap are arranged at the Lynette seats  212  of the working rolls. Because the Lynette seats are typically offset relative to the diameter of the rolls, the spacing, which is detected by the roll gap transmitter, between the Lynette seats and the reduced—due the larger diameter of the working rolls—height H of the roll gap obviously has to be calculated hereunder. 
         [0036]      FIGS. 7   a ) to  7   e ) show different forms of embodiment for roll gap transmitters  110  known in the prior art. All of these roll gap transmitters have a mechanism  114  in the form of a linkage for suitable positioning of measuring heads  112  with respect to the Lynette seats of the working rolls  210 . The mechanism or the linkage is typically biased with the help of a spring so that in this manner a respective predetermined spacing between measuring head and Lynette seat or surface of the working roll or a bearing of the measuring head against the Lynette seat or against the working roll is always guaranteed even in the case of vertical movement of the working rolls  210 . 
         [0037]      FIGS. 8   a ),  b ) and  c ) respectively show different examples for a displacement V of the working rolls  210  relative to the stand plane  200 - 10 . The stand planes are respectively spanned by the longitudinal axes of the upper and lower backing rolls  240 - 1 ,  240 - 2 . As  FIGS. 8   a ),  b ) and  c ) show, the working rolls  210  and thus the roll gap can be displaced not only in rolling direction, but also against the rolling direction with respect to the stand plane  210 . The amount of the displacement, i.e. the offset, is denoted in the figures by the reference symbol V. The direction of the offset with respect to the stand plane  200 - 10  is characterized by a corresponding sign + or −. The rolling direction is respectively characterized in  FIG. 8  by a horizontal arrow. 
         [0038]    The description of the invention follows: 
         [0039]      FIG. 1  shows the measuring device  100  according to the invention arranged in the roll gap of a roll stand between the upper working roll  210 - 1  and the lower working roll  210 - 2 . The measuring device  200  comprises a roll gap transmitter  110  for detecting the height of the roll gap between the two working rolls. The measuring device  100  additionally comprises an initialization device  120  for detecting a displacement of the working rolls  210  in or against the rolling direction from a starting position to an end position. The rolling direction is characterized in  FIG. 1  by the double arrow. 
         [0040]    The roll gap transmitter  110  comprises, according to  FIG. 1 , measuring heads  112  which are arranged in a suitable relative position with respect to the circumference of the working rolls  210 - 1 ,  210 - 2  or with respect to the circumference of the Lynette seat of the working rolls. The measuring heads  112  are connected by way of a linkage  114  with a display device  116  which displays the height of the working gap. The initialization device  120  is connected by at least one half thereof with the chock  224  of the lower working roll  210 - 2 . The initialization device  120  in the case of the embodiment shown in  FIG. 1  acts by way of a roll gap transmitter displacing device  130  directly on the roll gap transmitter  110 . The roll gap transmitter displacing device  130  comprises, in the case of the embodiment shown in  FIG. 1 , a linkage which is displaceably mounted in a slide sleeve. Through the direct coupling of the chock  224  by way of the initialization device  120  and the roll gap transmitter displacing device  130  to the roll gap transmitter  110  a displacement of the chock  224  and thus of the working rolls  210  in or against the rolling direction is advantageously transmitted directly synchronously to the roll gap transmitter  110 . In this manner it is advantageously ensured that even in the case of displacement of the working rolls in or against the rolling direction the relative position of the measuring heads  112  with respect to the surfaces of the working rolls  210  or the Lynette seats (not shown in  FIG. 1 ) and thus a desired measurement accuracy are maintained. 
         [0041]      FIG. 2  shows a plan view of the arrangement known from  FIG. 1 . The arrangement of the roll gap transmitters  110  at the lefthand and righthand Lynette seats  212  of the working roll  210 - 1  can be seen. The roll gap transmitters  110  are connected by way of the roll gap transmitter displacing device  130  with the initialization device  120 , which in turn directly contacts the chock  224  of the working roll  210 . The roll gap transmitter displacing device  130  has a degree of freedom in or against the rolling direction, recognizable at the arrangement of the displacing sleeve  115  parallel to the rolling direction  400 . 
         [0042]      FIG. 3  shows individual elements of a mounting of the working roll  210  in detail. The mounting serves for bridging over the spacing between the housings of the stand and the roll pins  215  of the working roll  210 . The spacing therebetween is occupied by a horizontal shifting (HS) displacing device in the form of, for example, a wedge adjustment. In the case of the embodiment shown in  FIG. 3 , the HS displacing device comprises a first wedge firmly connected with the housing of the roll stand  200  and a second wedge  221  sliding on the first wedge. A intermediate plate  220 , a bending cassette  223  and/or a chock  224  is or are typically connected with the wedge  221  in the direction of the roll pin of the working roll. 
         [0043]    All mentioned parts of the mounting, i.e. the movable wedge  221 , the intermediate plate  220 , the bending cassette  223  and the chock  224 , can each individually serve as a reference point for the initialization device  120  for detection of a displacement of the working rolls, because in this case the stated individual parts of the mounting are conjunctively moved in or against the rolling direction. 
         [0044]    In  FIG. 4  it can be seen that even in the case of an axial displacement  500  of the working rolls  210  the roll gap transmitters  110  do not have to be conjunctively axially displaced insofar as the axial displacement has no effects on the relative position of the roll gap transmitters  110  with respect to the Lynette seats or the roll pins of the working rolls, so that the relative position, which is required for a desired measurement accuracy, of the roll gap transmitters with respect to the Lynette seats are maintained. 
         [0045]    By contrast to  FIG. 1 ,  FIG. 5  shows an embodiment for the measuring device according to the invention in which the roll gap transmitter displacing device  130  also comprises a controlling and drive device  132 , which is constructed for moving the roll gap transmitter  110  actively in or against the rolling direction. This controlling and drive device  132  is required particularly if a direct mechanical coupling between the chock  224  and the roll gap transmitter  110  is not present. This can be the case, for example, if the initialization device  120  consists of two mechanically separate coupling halves of which one, for example, is connected with the chock  224  and the other with a linkage of the roll gap transmitter displacing device  130 . Alternatively, the controlling and drive device  132  can be required if the roll gap transmitter displacing device  130  does not provide a mechanism or a linkage between the initialization device and the roll gap transmitter  110 , but provides instead an optical or electrical transmission channel for transmission of the measurement signals of the initialization device, which represent the displacement of the working rolls, to the controlling and drive device. In both cases the controlling and drive device  132  serves for active adjustment of the roll gap transmitter  110  with respect to the displaced (end) position of the working rolls. In addition, the roll gap transmitter displacing device  130  together with the controlling and drive device  132  can have an operating mode for retracting the roll gap transmitter  110  into a rest or retracted position outside the roll gap and preferably also outside the roll stand. The adjustment of the roll gap transmitter with respect to the working rolls can take place simultaneously, i.e. synchronously, with or displaced in time with respect to the displacement of the working rolls  210 . 
       REFERENCE NUMERAL LIST 
       [0000]    
       
           100  measuring device 
           110  roll gap transmitter 
           112  measuring head 
           114  mechanism 
           120  initialization device 
           130  roll gap transmitter displacing device 
           132  controlling and drive device 
           200  roll stand 
           210 - 1  upper working roll 
           210 - 2  lower working roll 
           212  Lynette seat 
           215  roll pin 
           220  mounting of the working rolls 
           221  roll-side part of an HS displacing device 
           222  intermediate plate 
           223  bending cassette 
           224  chock (=bearing housing) of the working roll 
           240 - 1  backing roll 
           240 - 2  backing roll 
           300  rolling stock 
           400  rolling direction=HS displacement direction 
           500  axial displacement direction 
         H roll gap height 
         +V positive offset relative to stand plane 
         −V negative offset relative to stand plane