Patent Publication Number: US-2022219929-A1

Title: Web Transport Control Device

Description:
The invention relates to a web transport control device having a plurality of rotary frame units each of which comprises a carrier frame and a rotary frame which is parallel to the carrier frame and carries an input roller and an output roller for a material web to be controlled and which is pivotably supported on the carrier frame by means of a bearing, the device further comprising a web guiding system arranged such that each of a plurality of material webs is fed to one of the input rollers, is deflected thereat and is then deflected again at the output roller. 
     When running material webs are to be processed, e.g. in the manufacture of composite webs for tire carcasses, it is frequently required to merge a plurality of material webs in correct lateral alignment. The movement of each web must be steered or feedback-controlled such that the web is prevented from migrating in the direction transverse to the running direction. To that end, the web is threaded through the rotary frame unit such that it is respectively deflected, by 90° for example, at the input roller and at the output roller. If the running direction deviates from the desired direction, the rotary frame which carries the input roller and the output roller is rotated relative to the carrier frame such that the input and output rollers take another posture and steer the web back into the desired direction. 
     In most conventional rotary frame constructions, the input roller and the output roller are mounted, with their axes in parallel, on a plane that is parallel with the rotary frame but is offset from the plane of the rotary frame such that the rollers can rotate freely. The rotary frame and the carrier frame are approximately congruent and are also arranged in planes that are offset from one another, so that they can be pivoted relative to one another. Thus, as a whole, the rotary frame construction has a three-layer design. An example of such an arrangement is shown in US 2003/213867 A1. 
     The rotation center about which the rotary frame is pivoted relative to the carrier frame should ideally be positioned in the center of the incoming web, so that the pivotal axis is orthogonal to the plane of the rotary frame and extends tangentially with respect to the outer vertex of the input roller. In this way, it can be achieved that, when the rotary frame is pivoted, the incoming web remains practically stationary whereas the outgoing web is displaced in the desired direction. 
     A bearing with a virtual rotation center has the advantage that the ideal position for the pivotal axis can be realized without any mechanical axis or bearing elements that could collide with the incoming web being present in this position. The bearing construction must be stable enough to withstand the force that is caused by the tension of the web and has the tendency to drag the rotary frame away from the carrier frame. 
     DE 20 2017 100 819 U1 discloses a rotary frame construction that is outstanding in having a particularly small constructional height. 
     It is an object of the invention to provide a web transport control device with reduced space requirement. 
     According to the invention, in order to achieve this object, the rotary frame units are nested one in the other such that web sections of the plurality of webs that extend between the respective input and out rollers are parallel to one another and the spacing between two neighboring ones of these web sections is not larger than the sum of the diameters of the input and output rollers between which these web sections extend, and the input rollers of the plurality of rotary frame units are offset relative to one another in the direction parallel to the web sections. 
     Thanks to the nested arrangement of the rotary frame units and to the small spacings between these units in the direction normal to the planes of the frames, a very compact design of the entire web transport control system can be achieved. This leads not only to a reduction of the required installation space but also to a shortening of the path of travel of the webs, which makes it possible to achieve a more stable web transport and a simplified design of the web guide system. Thanks to the offset of the input rollers, the possibility to deflect the webs at these input rollers by 90°, respectively, is preserved. If the virtual rotation center of the rotary frame is located at the outer vertex of the input roller, then the pivotal axis of the rotary frame coincides with the center of the incoming web portion, so that, when the rotary frame is pivoted, this incoming web portion will only be subject to a torsion, whereas the web tension will remain essentially uniform over the entire width of the web. 
     Useful embodiments of the invention are indicated in the dependent claims. 
     If the input and output rollers of all rotary frame units have the same diameter, then the spacing between the parallel web sections is smaller than twice this diameter. In case of a Z-thread, the rotary frame units have, in a side view, an approximately L-shaped overall configuration, and the length of the shorter leg of the L corresponds to twice the diameter of the rollers. Then, the rotary frame units are nested in such a manner that they overlap also in the direction normal to the planes of the frames. 
     In one embodiment, all rotary frame units have the same dimensions. This enables not only an efficient production but has also the advantage that the output rollers are also offset from one another in the running direction of the web sections, so that a 90° deflection of the web portions may also take place at the output rollers. 
     In another embodiment, the web guide system is configured for a U-thread. In this case, the spacings between the input roller and the output roller are different for the different rotary frame units, and the U-shaped web paths are nested one in the other. 
    
    
     
       Embodiment examples will now be described in conjunction with the drawings, wherein: 
         FIG. 1  is a schematic view of a web transport control device according to a first embodiment; 
         FIG. 2  is a schematic top plan view of a rotary frame construction; 
         FIG. 3  shows the rotary frame construction with a slightly pivoted rotary frame; 
         FIG. 4  is a view of the rotary frame construction as seen in the direction of arrows IV-IV in  FIG. 2 ; 
         FIG. 5  is an enlarged side view of the rotary frame construction as seen in the direction of arrows V-V in  FIG. 2 ; and 
         FIG. 6  shows a web transport control device according to another embodiment. 
     
    
    
       FIG. 1  schematically shows the design of a web transport control device according to the invention having four rotary frame units E. All four rotary frame units have equal dimensions and an L-shaped overall configuration and are thereby designed for a Z-thread of four material webs B. Each rotary frame unit E has a stationary carrier frame  10  and a rotary frame  12  that is pivotable relative to the carrier frame. An input roller  14  and an output roller  16  are rotatably supported in each rotary frame  12 . A web guide system is formed by two sets of deflection rollers U, V over which the webs B are trained such that they are deflected by 90° at the input roller  14 , from the vertical direction into the horizontal direction in this example, and that they are deflected again by 90° at the output roller  16 . From the downstream deflection rollers V, the webs then converge to a roller pair R in the nip of which the webs are merged and laminated one upon the other so that, together, they form a composite web B′. 
     In the vertical portion between the output roller  16  and the downstream deflection roller V, the lateral position of each web is detected by means of a camera K. On the basis of these position data, the rotary movements of the rotary frames  12  are controlled such that the lateral position of each web is adjusted to a respective target value, so that the webs are laminated with the correct position register. 
     The planes of the carrier frames  10  of all four rotary frame units E are parallel to one another. Between the input roller  14  and the output roller  16 , each web B forms a web section b that is parallel with the plane of the frame. Thus, all four web sections b are parallel to one another. 
     In the example shown, the input rollers  14  and output rollers  16  of all four rotary frame units have an equal diameter. In this example, the spacing between two neighboring web sections b, measured in the direction normal to the plane of the frame, is only 1.5 times the diameter of the input and output rollers, so that the input roller  14  of each rotary frame unit (except the topmost one) overlaps in height with the output roller  16  of the next higher rotary frame unit. In this way, the L-shaped rotary frame units E are compactly nested one in the other. 
     An example for a possible design of an individual rotary frame unit E will now be explained in conjunction with  FIGS. 2 to 5 . 
       FIG. 2  shows a top plan view of one of the rotary frame units E. What can be seen here are the carrier frame  10  and the rotary frame  12  that is pivotable relative to the carrier frame about a virtual rotation center P.  FIG. 3  shows the rotary frame construction with the rotary frame slightly pivoted. For ease of distinction, all parts that belong to the (stationary) carrier frame  10  have been shown in bolder lines than the parts that are movable with the rotary frame  12 . 
     The input roller  14  and the output roller  16  are rotatably supported in the rotary frame  12 , and a material web which has not been shown and the movement of which shall be steered by means of the rotary frame construction is threaded over the input and output rollers. For example, in a Z-thread as in  FIG. 1 , the material web may, run downwards (in the direction away from the viewer in  FIG. 1 ) to the input roller  14  where it is deflected into the horizontal direction so as to be passed-on to the output roller  16  where it is deflected again so that it will then move downwards again. 
     The carrier frame  10  has a horizontal base plate  18  the greatest part of which is hidden by the rotary frame  12  in  FIG. 2 , so that only the left edge of the base plate  18  is visible. On the right side in  FIG. 2 , the base plate  18  forms a lever  20  that projects beyond the lateral edge of the rotary frame  12  and is connected to a bracket or a lever  24  of the rotary frame via an articulated linear drive  22 . When the linear drive  22  draws the levers  20  and  24  together, the rotary frame  20  pivots about the vertical pivotal axis that passes through the rotation center P, as has been shown in  FIG. 3 . This pivotal axis forms a tangent to the input roller  14 , so that the input roller and, therewith, the incoming material web does not make any lateral movement when the rotary frame  12  is rotated, whereas the output roller  16  and the outgoing material web are displaced in lateral direction. 
     The rotary frame  12  forms a gutter-shaped downwardly open casing  26  the top wall of which forms a cross-bar  28  for holding a cam plate  30  that is accommodated in the interior of the casing  26  and is connected to the cross-bar  28  by a wall member  32  that is trapezoidal in plan view. 
     The edge of the cam plate  30  forms, on the bottom side in  FIG. 2 , two control curves  34  shaped as circular arcs and, on the top side, another control curve  36  shaped as a circular arc. The control curves  34  and  36  are centered on the virtual rotation center P. In order to illustrate the curvature of the control curves  34 ,  36  more clearly,  FIG. 2  shows extended circular arc segments (continuous lines). Associated with each of the control curves  34 ,  36  is a follower roll  38  that is supported on the carrier frame  10  so as to be rotatable about a vertical axis. The three follower rolls  38  engage the edge of the cam plate  30  practically without play, so that this cam plate and, therewith, the entire rotary frame  12  can only perform a circular movement relative to the carrier frame about the virtual rotation center P. 
     Four brackets  40  that project vertically from the base plate and each support a support roller  42  have been welded onto the carrier frame  10 . Two of these support rollers  42  are accommodated in slots  44  ( FIG. 4 ) that extend horizontally in the legs of the trapezoidal wall member  32 . These legs of the wall member  32  are angled such that they extend tangentially to an arc of a circle around the virtual rotation center P. If a downwardly directed force (weight) acts upon the rotary frame  12 , then the top edges of the slots  44  are urged against the support rollers  42  so that the wall member  32  and, therewith, the entire rotary frame  12  are supported on the support rollers  42 . When the rotary frame is pivoted, there is a relative movement between the support roller and the slot, and the support roller rolls along the top edge of the slot. 
     In the case that the rotary frame  20  is subject to an upwardly directed force, the lower edges of the slots  44  are urged against the support rollers  42 , and in case of a pivotal movement, the support rollers will roll along these lower edges of the slots. The play of the support rollers  42  in the slots  44  is on the one hand so large that the support rollers can move with low friction and is on the other hand so small that the vertical movement of the wall member  32  relative to the support frame, as admitted by the play, remains within the admissible tolerances. 
     The casing  26  of the rotary frame  12  accommodates another wall member  46  that is trapezoidal in plan view and is fixed on the bottom side of the cross-bar  28 , and slots are formed in the angled legs of this wall member. Two of the four support rollers  42  are accommodated in these slots of the wall member  46 . The legs of this wall member are also angled such that they extend tangentially to an arc of a circle around the virtual rotation center P. The wall member  46  is therefore guided and supported with low play by the support rollers  42  in the same manner as the wall member  32 . All in all, the engagement of the support rollers  42  in the slots  44 ,  48  prevents a vertical movement of the rotary frame relative to the carrier frame, and the rotary frame and the carrier frame are held in exact parallel alignment. 
     A holder  50  for one end of a tension spring  52  is mounted on the base plate  18  of the carrier frame and on the lever  20  formed by this base plate. The other end of the tension spring is anchored at the lever  24  of the rotary frame  12 , so that a permanent tensioning force is produced that has the tendency to draw the levers  20  and  24  together and to rotate the rotary frame  12  counter-clockwise relative to the carrier frame  10 . However, the linear drive  22  is self-arresting at least in the direction in which its length decreases, so that the torque exerted by the tension spring  52  does not actually cause a rotation of the rotary frame  12 . However, the elastic bias that is cause by the spring  52  has the effect that any play in the bearing formed by the control curves  34 ,  36  and the follower rolls  38  as well as any play in the linear drive  22  and its articulated joints with the levers  20 ,  24  is eliminated. 
     When the web transport control device is operating, the lateral position of the material web is detected by means of a sensor, and the linear drive  22  is controlled by means of a controller such that the position of the material web is adjusted to a target value. In this feedback-control process, the linear drive  22  is alternatingly extended and retracted in order to rotate the rotary frame in the one direction or the other. The tension spring  52  assures that no hysteresis occurs in this control process because the spring will always hold all components of the system in which a certain play may occur at the same limit of the range of movement that is admitted by the play. 
       FIG. 4  shows the rotary frame construction in a front view. Welded on the base plate  18  of the carrier frame  10  is a support plate  54  on which the follower rolls  34  are rotatably supported. 
     The brackets  40  for the support rollers  42  are also welded to the support plate  54 . In order to assure an exact positioning and safe immobilization of the brackets  40 , these brackets are formed, on the edge facing the support plate  54 , with pegs which have not been shown and which engage in corresponding peg holes of the support plate  54 . 
     In  FIG. 4 , the wall member  46  is largely obscured by the wall member  32  that is disposed in front thereof, so that what is visible are only downwardly projecting studs  66 . These studs are formed at their bottom ends with pegs  68  for engagement in peg holes  70  of the cam plate  30 . The cam plate  30  is welded to the pegs  68  and is thereby immobilized in its position in the rotary frame  12 . For further stabilization, the cam plate  30  has projections  72  at both ends, these projections being in form-fitting engagement with corresponding recesses in side walls  74  of the casing  26 . 
       FIG. 5  shows the rotary frame construction in a side view. Of the carrier frame, only the base plate  18  is visible here. The side walls  74  of the casing  26  of the rotary frame are prolonged at both ends to form bearing brackets  76  for the input roller  14  and the output roller  16 . These bearing brackets may have different shapes, depending upon the desired type of threading of the material web.  FIG. 5  shows the configuration for Z-thread. 
     Without the bearing brackets  76  and the input roller  14 , the entire constructional height of the rotary frame construction is only slightly larger than the diameter of the input and output rollers  14 ,  16 . Moreover,  FIG. 5  shows one of the projections  72  of the cam plate that penetrate the side wall  74 . 
       FIG. 6  illustrates another possible embodiment of a web transport control device, having two rotary frame units E 1  and E 2  that are configured for a nested U-thread. The horizontal web sections b between the input roller and the output roller extend in parallel and have the same spacing as in  FIG. 1 . The input rollers of the two rotary frame units are offset in the running direction of the web sections b so far that the incoming web portions that are deflected at the deflection rollers U can both extend in vertical direction and in parallel with one another. 
     In the example shown, the output rollers  16  are also offset from one another so that the outgoing web portions that pass-on to the deflection rollers V may also extend in vertical direction and in parallel with one another. Since only two webs B are present in this example, the cameras K for position detection can be arranged on opposite sides of the webs, so that the spacing between the outgoing web portions may be kept very small. 
     In another embodiment, the output rollers  16  may be arranged vertically one above the other, and the deflection rollers V may be arranged such that the outgoing web portions are slightly tilted relative to the vertical and therefore lie in different planes.