Abstract:
A rolling mill, in particular a rolling mill having more than one mill stand, includes at least two rolls which are mounted in a roll bearing in a mill stand to absorb rolling forces, movers for moving at least one roll relative to the mill stand as well as determining devices for determining the roll pass, the determining device having a pass reference and a spatial reference as well as a measuring device for measuring the relative position between the pass reference and the spatial reference. At least one of the pass reference and the spatial reference is arranged peripherally in relation to the power flow occurring between the roll and the mill stand.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a divisional of and Applicant claims priority under 35 U.S.C. §§120 and 121 of U.S. patent application Ser. No. 14/346,393 filed on Apr. 4, 2014, which application is a national stage application under 35 U.S.C. §371 of PCT Application No. PCT/DE2012/000938 filed on Sep. 24, 2012, which claims priority under 35 U.S.C. §119 from German Patent Application No. 10 2011 114 143.3 filed on Sep. 23, 2011, the disclosures of each of which are hereby incorporated by reference. A certified copy of priority German Patent Application No. 10 2011 114 143.3 is contained in parent U.S. patent application Ser. No. 14/346,393. The International Application under PCT article 21(2) was not published in English. 
     
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
       [0002]    The invention relates to a rolling mill, particularly to a multi-stand rolling mill, having at least two rolls mounted in a roll stand, in a roll bearing, to absorb rolling forces, having means for displacement of at least one roll with reference to the roll stand, and having means for determining the roll pass, wherein the determination means have a pass reference and a spatial reference, as well as means for measuring the relative position between the pass reference and the spatial reference. Likewise, the invention relates to a rolling method in which rolls are positioned on-line, to a desired roll pass, taking into consideration measurement results of means for determining a roll pass. 
       2. Description of the Related Art 
       [0003]    Such rolling mills and rolling methods are actually known, whereby the means for determining the roll pass are disposed in positioning cylinders with which the rolls can be positioned, and determine the roll pass, in each instance, by way of the cylinder position or by way of the position of the corresponding piston. In this connection, the determination regularly takes place by way of a spatial reference, which is assumed, by definition, to be fixed in space, and by way of a pass reference, the position of which serves as a measure for the position of the corresponding roll and thereby as a measure for the roll pass. 
       SUMMARY OF THE INVENTION 
       [0004]    It is the task of the present invention to make available a rolling mill of the stated type and a rolling method of the stated type, which allow the most precise information possible concerning the roll pass. 
         [0005]    As a solution, rolling mills and rolling methods having the characteristics of the independent claims are proposed, which actually allow providing information about the roll pass during rolling, in some cases. Further advantageous embodiments are found in the dependent claim and the following description. 
         [0006]    Thus, a rolling mill of the stated type can be characterized in that the pass reference and/or the spatial reference is/are disposed peripheral to the force flow, with reference to a force flow that occurs between roll and roll stand. In this way, distortions of the measurement results, in each instance, caused by rolling forces, can be minimized, and correspondingly, the most precise information possible concerning the roll pass can be maximized. This particularly holds true also in comparison with the known rolling mills, in which pass reference and spatial reference are disposed, in each instance, in the cylinder that is put under pressure to apply the rolling forces. Accordingly, of course, force-related influences must be expected. 
         [0007]    It is particularly advantageous if the spatial reference is disposed outside of a force introduction region in which the rolling forces are introduced into the roll stand. In this way, the influence of stresses caused by the rolling forces can be minimized. Furthermore, it has turned out that in this way, maintenance problems can also be minimized, because corresponding regions are frequently more easily accessible. Preferably, the spatial reference is disposed outside of the force introduction region of the roll that is being measured at a specific time. In particular, it is accordingly advantageous if each spatial reference is disposed outside of a force introduction region in which rolling forces are introduced into the roll stand. In this manner, a spatial reference that is as locally fixed as possible can be made available, so that the corresponding measurement results are not or only minimally impaired. 
         [0008]    It is also possible to dispose the spatial reference, and preferably every spatial reference of at least one roll stand, on the roll stand in the vicinity of a neutral region of the roll stand, between two force introduction regions in which rolling forces are introduced into the roll stand. In this way, as well, the influence of roll stresses or forces can be minimized. 
         [0009]    In this connection, it should be explained that the term “in the vicinity” in the present connection means that the spatial reference is disposed at a distance from the neutral region of twice the minimal thickness of the roll stand or less, or twice the minimal radial thickness of or less. Naturally, a neutral region is subject to relatively little stress, so that accordingly, a change in stresses caused by the rolling forces can also exert less of an influence. In this connection, the “thickness of the roll stand” in the present connection is defined as the thickness of the roll stand parallel to the pass line or in the direction of the pass line of the rolling mill, while the “radial thickness” is defined as the thickness of the roll stand radially or perpendicular to the pass line. Both variables, particularly in their minimum value, represent a relatively reliable and practically reproducible measure for the important dimensioning present in the roll stand, in each instance, with regard to the force distribution. 
         [0010]    A pass reference disposed peripheral to the force flow can be implemented in particularly simple and operationally reliable manner if the pass reference is disposed on a projection free of rolling forces. The projection then follows the corresponding movement of the body on which the projection free of rolling forces is disposed, without being subject to possible stresses or moments. In this connection, it is advantageous to dispose this projection free of rolling forces as closely as possible in the vicinity of the roll, for example on a rocker that carries the roll by way of a bearing, or on a non-rotating module of the bearing itself. 
         [0011]    In order to minimize measurement errors caused by roll stresses or rolling forces, and therefore advantageously with regard to the most precise information possible concerning the roll pass, the pass reference can be disposed at a distance from the roll bearing of less than one bearing diameter of the roll bearing. This is accordingly advantageous even independent of the other characteristics, in the case of rolling mills of the stated type. In this way, it is ensured that the pass reference is disposed as closely as possible to the roll itself. 
         [0012]    Likewise, the closest possible placement of the pass reference to the roll can be implemented if at least one of the rolls is mounted in a bearing body and the pass reference is disposed on the bearing body. In this way, too, fewer measurement errors occur as the result of roll stresses or rolling forces, so that accordingly, the most precise information possible concerning the roll pass is made possible. It is understood that placement of the pass reference on the bearing body is advantageous even independent of the other characteristics of the present invention, in the case of a rolling mill of the stated type. 
         [0013]    Preferably, the bearing body has a rocker having a bearing side that serves as the bearing body, on which side a displacement means for displacement of the roll, in each instance, such as, for example, the piston or the cylinder of a piston/cylinder unit, acts, and having a guide side, whereby the pass reference is provided on the side of the bearing side facing away from the guide side. Such an arrangement lies peripheral to the force flow, so that accordingly, measurement errors are minimized. It is understood that other displacement means, such as electromechanical displacement means, if applicable with a hydraulic fixation element, for example, can also be used in place of piston/cylinder units. 
         [0014]    The measurement means can comprise a distance measurement device that measures the distance between pass reference and spatial reference. In this manner, a conclusion can be drawn concerning the roll pass, in simple and reliable manner, from the distance between pass reference and spatial reference, because for this purpose, only corresponding geometrical conversions are required. If applicable, however, a calibration step can be undertaken before rolling, during which step the changes in the measurement result of the measurement means are recorded in calibrating manner, as a function of the roll position. 
         [0015]    Preferably, the distance measurement device is configured to be tactile or to make contact, so that it yields measurement results in cost-advantageous and precise manner, particularly even in the presence of dust and steam. 
         [0016]    Also, a rolling mill of the stated type can be characterized in that the spatial reference is disposed separate from the roll stand. In this way, it is ensured, in every case, that the spatial reference is independent or roll stresses or rolling forces, whereby if applicable, maintenance problems due to difficult accessibility or due to affixing of the measurement means on the spatial reference or on the pass reference must be accepted, if the roll stand or, alternately, only the pass reference and the module that carries the pass reference are supposed to be removed for maintenance work or re-fitting work and brought back into the rolling mill. On the other hand, in this manner the most precise information possible concerning the roll pass can be ensured. 
         [0017]    The determination means or the measurement means can be calibrated by means of off-line calibration means that allow a measurement of the roll pass directly on at least one roll. This then makes it possible to predict the reaction of the roll, in each instance, if the rolls are acted on by way of the displacement means, in accordance with the measurement results of the measurement means or determination means. 
         [0018]    Preferably, the rolling mill has a regulation circuit for regulating the roll pass, which circuit comprises the determination means, and input means for measurement results of the calibration means as a guide variable of the regulation circuit, as a correction variable for the setting variable of the regulation circuit and/or as a correction variable for the determination means or the displacement means. In this manner, the measurement results that result from the calibration by means of the off-line calibration means can be introduced into the regulation circuit. In this connection, there are various possibilities for using these measurement results in a practical manner. Ultimately, what is most advantageous here depends on the concrete conditions, in each instance. Thus, these measurement results can serve merely for a correction of the measurement results of the determination means or measurement means. Likewise, a correction of the setting variable or a correction of the action on the displacement means or on their own control circuit can take place. 
         [0019]    More precise information concerning the roll pass can be confirmed by means of an off-line calibration of the determination means before rolling. It is understood that this can be used accordingly advantageously even independent of the other characteristics of the present invention, in the case of a rolling method of the stated type. 
         [0020]    In this connection, it is understood that such a calibration does not have to take place every time before every rolling process. Instead, such a calibration can be undertaken in the case of more extensive re-fitting work, for example, or in the case of maintenance work. 
         [0021]    In this connection, it should be explained that the term “off-line” specifically relates to work, activities or devices that are only used when no rolling is taking place in the rolling mill. 
         [0022]    Preferably, the off-line calibration takes place in-line, in other words when the rolls, in each instance, or the related roll stands are disposed in the rolling segment. Accordingly, it is also advantageous if the off-line calibration means are disposed or can be disposed directly on the rolling mill, in order to be able to measure the rolls in-line. 
         [0023]    On the other hand, it is also possible to carry out out-line measurements, in order to measure the roll pass directly. 
         [0024]    Preferably, for off-line calibration, the position of the rolls is measured directly, in order to be able to calibrate the measurement means or determination means as precisely as possible in this manner. 
         [0025]    Positioning of the rolls can take place within a regulation circuit for taking the measurement results of the determination means into consideration, so that the rolls are positioned as optimally as possible in each instance. If applicable, the regulation circuit can also use measurement results from work piece measurements downstream from the rolling mill, such as, for example, pipe wall thickness measurements or cross-sectional measurements, as a regulation variable. 
         [0026]    In the present connection, the term “roll stand” refers to any structural unit that applies and compensates the forces that occur during rolling and are required for rolling deformation. In this regard, a roll stand can be provided and designed as a frame and structurally movable unit for rapid changing processes, but this is not absolutely necessary. Instead, the roll stand can also be connected with the rest of the rolling mill in relatively rigid manner, so that changing processes, such as, for example, replacement of rolls or other wear parts, require greater installation activities. 
         [0027]    It is understood that the characteristics of the solutions described above and in the claims can also be combined, if applicable, in order to be able to implement the advantages accordingly cumulatively. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0028]    Further advantages, aims, and properties of the present invention will be explained using the following description of exemplary embodiments, which are particularly shown also in the attached drawing. The drawing shows: 
           [0029]      FIG. 1  a schematic side view of a rolling mill; 
           [0030]      FIG. 2  a schematic front view of a roll stand that can be used in the rolling mill according to  FIG. 1 , having a reference support attached independent of a roll stand; 
           [0031]      FIG. 3  a schematic front view of a further roll stand that can be used in the rolling mill according to  FIG. 1 , having a reference support attached on the roll stand in neutral regions of the roll stand; 
           [0032]      FIG. 4  a schematic front view of a further roll stand that can be used in the rolling mill according to  FIG. 1 , having reference supports attached on the roll stand in neutral regions of the roll stand; 
           [0033]      FIG. 5  a schematic front view of a further roll stand that can be used in the rolling mill according to  FIG. 1 , having reference supports attached on the roll stand in neutral regions of the roll stand; 
           [0034]      FIG. 6  a schematic front view of a further roll stand that can be used in the rolling mill according to  FIG. 1 , having reference supports attached on the roll stand in neutral regions of the roll stand, and eccentric bushings for positioning of the rolls; 
           [0035]      FIG. 7  a schematic front view of a further roll stand that can be used in the rolling mill according to  FIG. 1 , having reference supports attached independent of the roll stand, and eccentric bushings for positioning of the rolls; and 
           [0036]      FIG. 8  a section through a distance measurement device, in which the measurement electronics, in particular, have been removed, and therefore can be disposed outside of an area subject to a high temperature and/or great mechanical stress. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0037]    The rolling mill  1  shown schematically in  FIG. 1  comprises a plurality of roll stands  20  each having rolls  30  mounted on the roll stands  20 . The roll stands  20  are aligned along a pass line  2 , so that a work piece can pass through the rolls  30  along the pass line  2 , from an input side  12  to an output side  13 . 
         [0038]    The space situated between the rolls  30 , in each instance, is referred to as the roll pass and is therefore a measure of the extent to which the rolls  30  act on the work piece, in each instance. 
         [0039]    It is directly comprehensible that precise knowledge of the roll pass, in each instance, allows influencing the rolling process in advantageous manner. 
         [0040]    The rolls  30  of the exemplary embodiment concretely shown in  FIG. 1  are mounted in rockers  45  as bearing bodies  70 , whereby the bearing body  70  is configured in a bearing side  46  of the rockers  45 . 
         [0041]    The rockers  45  furthermore have a guide side  47  that ultimately defines the movement possibilities of the rocker  45 , in that this side guides the rocker  45 , in each instance. 
         [0042]    For this purpose, the bearing side  46  and the bearing body  70  have a roll bearing  35 , which bears the roll  30 , in each instance. 
         [0043]    A projection  75  free of rolling forces is disposed on the side of the bearing side  46  facing away from the guide side  47 , which projection can be used as a pass reference  54 , as will be explained in detail below, using the further exemplary embodiments. As is directly evident, this projection  75  free of rolling forces and therefore the pass reference  54  are disposed away from the roll bearing  35  by less than the bearing diameter of the roll bearing  35 . Also, it is directly comprehensible that the pass reference  54  or the projection  75  free of rolling forces is disposed peripheral to the force flow with reference to a force flow that occurs between the roll  30 , in each instance, and the roll stand  20 . In this connection, it must be taken into consideration that on the bearing side  46 , facing away from the pass, a piston/cylinder unit  42  can apply force to the rolls, in each instance, in the direction toward the pass or the pass line  2 , as is explained as an example in  FIGS. 2 to 5 . As can be seen from  FIG. 1 , the corresponding contact surface on which the piston/cylinder unit  42  can engage is disposed far removed from the projection  75  free of rolling forces or the related pass reference  54 , so that the latter can be found peripheral to the force flow. In deviating embodiments, other displacement means  40 , such as electromechanical displacement means, for example, if applicable having a hydraulic fixation element, can also be used in place of the piston/cylinder units  42 . 
         [0044]    In the exemplary embodiment shown in  FIG. 2 , three rolls  30  are disposed on the roll stand  20  and are mounted so that they can be positioned by way of rockers, whereby the positioning takes place by means of the piston/cylinder units  42 , which support themselves on the rockers  45 , on the one hand, and on the roll stand  20 , on the other hand, and in turn absorb the rolling forces and serve for pass positioning. 
         [0045]    Force introduction regions  24 , in which the supporting force and therefore the rolling force is introduced into roll stand  20 , lie, in each instance, where the piston/cylinder units  42  support themselves on the roll stand  20 , in each instance, as displacement means  40  that displace the rolls  30 . 
         [0046]    Each of the rockers  45  has a projection  75  free of rolling forces, as was already explained with regard to  FIG. 1 . 
         [0047]    Distance measurement devices  60  are disposed on the projections  75  free of rolling forces, in each instance, which devices support themselves on a support ring  78  that forms the spatial reference support  77 . 
         [0048]    With regard to each distance measurement device  60 , a pass reference  54  is disposed on every projection  75  free of rolling forces, and a spatial reference  56  is disposed on the spatial reference support  77 , which references, together with the measurement means  58  embodied by the distance measurement devices  60 , form means  50  for determining the roll pass. 
         [0049]    In the exemplary embodiment shown in  FIG. 2 , the support ring  78  or the spatial reference support  77  is attached independent of the roll stand  20 , so that the spatial references  56  are disposed separate from the roll stand  20 . 
         [0050]    The exemplary embodiment shown in  FIG. 3  corresponds, in essential parts, to the exemplary embodiments according to  FIGS. 1 and 2 , so that no renewed description of all the details will be presented here. However, in the exemplary embodiment shown in  FIG. 3 , the support ring  78  is attached to the roll stand  20 , but this takes place in neutral regions  25 , which can be found, in each instance, between two force introduction regions  24 . In this manner, stresses that could be conducted into the spatial reference support  77  and could lead to displacement of the spatial references  56  can be reduced to a minimum. If necessary, a movable attachment, which therefore equalizes displacements, of the support ring  78  on the roll stand  20  can be provided. 
         [0051]    As is directly comprehensible, the spatial reference  46  is disposed outside of a force introduction region, in each instance, in which the rolling forces are introduced into the roll stand  20 , in this arrangement as well. 
         [0052]    The arrangement shown in  FIG. 4  essentially corresponds to the arrangement according to  FIG. 3 , whereby here, however, a support ring  78  as a spatial reference support  77  is not provided. Instead, individual support arms  79  are disposed in neutral regions  25  of the roll stand  20 , in each instance, which arms serve as spatial reference supports  77 . Such an arrangement already leads to the result that the spatial references  56  are disposed outside of the force introduction region  24  and thereby peripheral to the force flow. 
         [0053]    In the exemplary embodiment shown in  FIG. 5 , as well, extensions situated on the roll stand  20 , which are set on in neutral regions  25  and project into the interior of the roll stand  20 , serve as support arms  79 . Depending on the concrete embodiment, the support arms  79  can also be configured in one piece with the roll stand  20 . 
         [0054]    Furthermore, the roll stand  20  according to  FIG. 5  is merely a two-roll stand, while the arrangements according to  FIGS. 2 to 4  are three-roll stands, in each instance. It is understood that in deviating embodiments, roll stands  20  having four and more rolls can also easily be used accordingly. For the remainder, the exemplary embodiment according to  FIG. 5  does not differ further from the exemplary embodiment shown in  FIG. 4 , so that no repetition to explain modules having the same effect will be given here. 
         [0055]    The arrangement shown in  FIG. 6  essentially corresponds to the arrangement according to  FIG. 5 , whereby in the exemplary embodiment shown in  FIG. 6 , eccentric bushings  41  are used as displacement means  40 , and surface areas of the eccentric bushings  41 , which are displaced coaxial to the axis of the roll, along with it, are used as the pass reference  54 . 
         [0056]    The eccentric bushings  41  are disposed on stand arms  21 , which in turn are firmly attached to the roll stand  20 , whereby accordingly, force introduction regions  24  into the roll stand  20  can be found in the area of this attachment. Depending on the concrete implementation of this exemplary embodiment, the stand arms  21  can also be configured in one piece with the roll stand. 
         [0057]    In the exemplary embodiment shown in  FIG. 7 , which corresponds, in most parts, to the exemplary embodiment according to  FIG. 6 , the spatial reference support  77  or the support arms  79  are disposed independent of the rolls stand  20 , as was already explained, as an example, using the exemplary embodiment shown in  FIG. 2 , so that the spatial references  56  remain uninfluenced by any rolling forces. 
         [0058]    The arrangement according to  FIG. 8 , for example, can be used as a distance measurement device  60 , in which a measurement tip  61  is provided, having a measurement contour  62  adapted to the movement of the references  54 ,  56 , a measurement foot  63  that lies opposite this measurement contour  62  or the measurement tip  61 , and a spring  64  that maintains the distance between the measurement tip  61  and the measurement foot  63 , and in which the measurement electronics, in particular, can be disposed spatially removed and thereby outside of an area subject to a high temperature and/or great mechanical stress, as this can generally be found in the vicinity of the roll during rolling. 
         [0059]    For this purpose, the distance measurement device  60  according to  FIG. 8  has a waveguide  65  that can measure the distance between measurement tip  61  and measurement foot  63 , in each instance, interacting with a magnet  66 , whereby the actual evaluation of the measurement result determined by way of the waveguide  65  can then take place far outside. 
         [0060]    The distance measurement device  60  is affixed, with its measurement foot  63 , either on the pass reference  54  or on the spatial reference  56 , for example, so that the measurement tip  61  sits on the related counter-piece of this pass reference  54  or of the spatial reference  56 , in each instance. 
       REFERENCE SYMBOL LIST 
       [0000]    
       
           1  rolling mill 
           2  pass line 
           12  input side 
           13  output side 
           20  roll stand 
           21  stand arm (numbered as an example) 
           24  force introduction region (represented as an example) 
           25  neutral region (represented as an example) 
           30  roll 
           35  roll bearing 
           40  displacement means (numbered as an example) 
           41  eccentric bushing 
           42  piston/cylinder unit (numbered as an example) 
           45  rocker (numbered as an example) 
           46  bearing side (numbered as an example) 
           47  guide side (numbered as an example) 
           50  determination means (numbered as an example) 
           54  pass reference (numbered as an example) 
           56  spatial reference (numbered as an example) 
           58  measurement means (numbered as an example) 
           60  distance measurement device (numbered as an example) 
           66  measurement tip 
           62  measurement contour adapted to the references  54 ,  56   
           63  measurement foot 
           64  distance-maintaining spring 
           65  waveguide for measurement 
           66  magnet 
           70  bearing body 
           75  projection free of rolling force 
           77  spatial reference support 
           78  support ring 
           79  support arm