Patent Document

BACKGROUND OF THE INVENTION 
       [0001]    This present disclosure relates to roll forming machines, specifically how the individual stations are driven. Each station has an upper roller and a lower roller that pinch the material to progressively shape it. Each roller must be rotationally driven to move the material along and assist the forming. Currently, the stations are all driven from one power source, commonly an electric motor. The shaft of the electric motor is affixed to a single gearbox, where the rotation from the motor is then divided up and split up into several output shafts, each driving a roller. For example, in U.S. Pat. No. 5,450,740, one gearbox drives several rollers. Because of slightly different speeds of both upper and lower rollers, along with slightly different speeds of the rollers from station to station, a fixed gearbox that provides the exact same rotational speed to each roller, binding and torque spikes can occur. Further, windup (where a biased torque builds up between two rotating members) causes uneven load, rapid tooling wear, roll scuffing of the material, and possibly catastrophic failure of the gearbox. An improved roll former and driving mechanism are needed. 
       SUMMARY OF THE INVENTION 
       [0002]    The present disclosure describes an improvement to a roll former. As is known in the art, roll formers have a series of rollers. In this invention, each roller is driven independently, allowing significant flexibility in tooling and appropriate speed settings from roller to roller and station to station. Instead of a traditional gearbox arrangement, individual motors (electric or hydraulic) drive individual rollers. As is typical of a roll former, the individual output shafts of the motors are coupled to the rollers through shafts with flexible joints on each end. Frequently, each motor has its own gearbox to reduce the output speed and increase torque output, as roll forming lines can run slower than an optimum motor rotational speed. As material is fed into the machine, the operator can tailor speed and torque unique to each roller to optimize the process and reduce wasted power. The invention provides significant benefits over the prior art. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0003]    A preferred embodiment of this invention has been chosen wherein: 
           [0004]      FIG. 1  is a front view of one station of the roll forming machine with portions shown in section to illustrate the arbor connections; 
           [0005]      FIG. 2  is a front view of the station in  FIG. 1  with the upper and lower rollers disengaged from the arbor connections; 
           [0006]      FIG. 3  is a front view of the roll forming machine of  FIG. 2  with the movable portion of the mill stand rotated; 
           [0007]      FIG. 4  is a side view of the roll forming machine; 
           [0008]      FIG. 5  is a top view of the roll forming machine of  FIG. 4 ; and 
           [0009]      FIG. 6  is a view of the display panel showing individual torque for each roller. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0010]    As is known in the art, a roll forming machine takes a flat strip of material and shapes it into a continuous cross-sectional desired shape, such as tubing. Frequently, the roll forming machine is a portion of a production line where the flat strip is provided to the machine from another machine, such as an uncoiler or slitter. After the machine makes the tubing, the tubing may be finished by other processes, such as cutting, end finishing, and stacking. This specification is primarily dedicated to the machine portion of the production line. 
         [0011]    Referring first to the drawings of  FIGS. 4 and 5 , reference numeral  10  generally designates a roll forming line, commonly used in making cylindrical tubes from sheet metal products. As shown in  FIG. 4 , a typical line  10  includes numerous machines which form the various sections of the line. These include forming section  12 , which includes mill stands  13 ,  14 ,  15 ,  16  and  17 ; a cluster section  18  which includes mill stands  19 ,  20  and  21 ; a finishing section  22  which includes mill stands  23 ,  24 ,  25  and  26 ; a welding section which includes mill stands  27 ,  28  ad  29 ; a cooling section  30 ; a sizing section  31  which includes mill stands  32 ,  33 ,  34 ,  35  and  36 ; and a squaring section  37  which includes mill stands  38 ,  39 ,  40  and  41 . Sheet steel enters the line  10  from an uncoiler (not shown) at forming section  12  and exits line  10  after passing through squaring section  37 . Line  10  roll gradually forms flat sheet steel into cylindrical tubes, which are cut to specified lengths after exiting the squaring section  37 . 
         [0012]    The general process by which cylindrical tubing is formed from flat sheet steel is well-known and will not be described in detail in the interests of clarity. Generally, it is preferable if at least mill stands  13 ,  14 ,  15 ,  17 ,  23 ,  24 ,  25 ,  33 ,  35 ,  38 ,  39  and  40  are constructed according to the principles of this invention. Since the construction of these mill stands is generally the same, a detailed description will be provided only for mill stand  13  with the understanding that this general construction will apply to all affected mill stands which utilize the principles of this invention. 
         [0013]    As an example, mill stand  14  is shown in elevation in  FIG. 1 , and illustrates the working position of the mill stand. Mill stand  14  includes main support frame  42  which includes spaced rail coupling brackets  46  (one shown) located on both sides of the support frame  42 . Frame  42  is supported above slide rails  48 ,  49  by brackets  46  which slidably connect the frame to the rails for relative sliding movement between the work position of  FIG. 1  and the retracted standby and changeover positions of  FIGS. 2 and 3 . 
         [0014]    Power driven cylinder  50 , typically a hydraulic cylinder having an extensible push rod  52  is fixedly secured to rails  48 ,  49  or to bracket  58  of drive frame  60  as shown. A lower connecting bracket  54  of frame  42  is connected to the terminal end of push rod  52  as by bolt  56  to allow for linear translation of movement between the push rod  52  and bracket  54 . 
         [0015]    Upright drive frame  60  is fixed to support table  62  by conventional means. Drive frame  60  carries spaced bearing blocks  64 ,  66 . Lower bearing block  64  is fixedly connected to drive frame  60  and includes collar  68  and sleeve  70 . Upper bearing block  66  is adjustably connected to drive frame  60  as by block  72  and jackscrew  74  and also has a collar  76  and sleeve  78 . Motor  80  is supported atop drive frame  60  and includes rotatable drive shaft  82  which terminates in coupler  84 . Drive shaft  82  extends through gear box  86  which is mechanically connected to jackscrew  74  so as to translate rotational movement of the drive shaft  82  into rotational movement of the jackscrew  74 , and corresponding linear movement of bearing block  66 . 
         [0016]    As shown in  FIG. 1 , motor assemblies  140 ,  142  are attached to a driving frame  88 . The upper motor assembly  140  has an upper motor  144  and a gearbox  146  that is associated only with its corresponding motor  144 . As shown, the upper motor  144  is affixed to the gearbox  146 , which is then affixed to an upper drive shaft  91 . The lower motor assembly  142  has a lower motor  148  and a gearbox  150  that is associated only with its corresponding motor  148 . As shown, the lower motor  148  is affixed to the gearbox  150 , which is then affixed to a lower drive shaft  90 . Both drive shafts  90 ,  91  extend from driving frame  88  and are connected via universal joints  92  and  93  respectively and driving features  94 ,  95  to bearing blocks  66  and  64 . Driving features  94  and  95  extend into a respective sleeve  78 ,  70  of bearing blocks  66 ,  64  respectively. The driving features  94 ,  95  are rotatable within the sleeves  78 ,  70 . 
         [0017]    Frame  42  supports arbor frame  96  which includes spaced upright turrets  98  and  99 . Plate  100  serves to connect turrets  98  and  99  and supports gear boxes  102  and  103 . Gear boxes  102 ,  103  are used to drive height adjustment of upper arbors  114 ,  116 . Couplings  104 ,  105  respectively are connected to and extend from gear boxes  102 ,  103 . Jackscrews  106  and  107  extend through and are mechanically connected to gear boxes  102 ,  103  for translational movement. 
         [0018]    Outboard housing turret  98  carries and supports bearing blocks  108 ,  109 . Bearing block  108  is fixedly connected to turret housing  98  and is generally aligned with bearing block  64 . Bearing block  109  is vertically adjustable and is connected to turret  98  as by block  110  connected to jackscrew  106 . Turret  99  supports bearing blocks  111  and  112  in a similar fashion. 
         [0019]    A first pair of rotatable arbors  113  and  114  is carried in bearing blocks  108  and  109 . A second pair of arbors  115  and  116  is rotatably housed in bearing blocks  111  and  112 . Forming rollers  117  and  118  are carried by and supported on arbors  113  and  114  respectively. The configuration and size of rollers  117 ,  118  will depend upon the predetermined size and desired shape of pipe to be formed, and by the position of the particular mill stand  13  in line  10 . Since sheet steel is gradually bent to form pipe, the rollers  117 ,  118  will vary slightly in configuration as the line  10  progresses. The basic process of forming pipe from sheet steel is well known and does not form part of this invention. Collars  120  serve to secure rollers  117 ,  118  to arbors  113 ,  114  to prevent relative movement therebetween. In the embodiment shown, rollers  117  and  118  rotate along with arbors  113 ,  114  with no relative rotation taking place. 
         [0020]    Arbor frame  96  includes a lower table  122  which is rotatably supported atop frame  42  as by bearing  124 . Drive means (not shown) is connected to table  122  and serves to rotate the table about a vertical axis. 
         [0021]    Arbors  115  and  116  are also adapted to carry rollers (shown in dotted line form)  127 ,  128 . The construction of arbors  115 ,  116  is the same as arbors  113 ,  114 . Each arbor  113 - 116  includes a driven feature  129 ,  130 ,  131 ,  132  which mates with driving feature  94  or  95 , depending upon the position of the arbor, when the arbor frame  96  is in the work position. 
         [0022]      FIGS. 1-3  illustrate the functionality and operation of mill stand  14 . Because of the many variations in wall thickness and pipe sizes, roll forming companies must often change the rollers used in a given line. Also, due to manufacturing considerations, each mill stand is positioned relatively close to an adjacent stand to prevent slack from developing in the steel as it passes through the line, as shown in  FIG. 5 . The relatively close positioning of mill stands prevents on-line changing of rollers without physically removing the individual mill stands from the pass line. 
         [0023]    Mill stand  14  is shown in the working or on-line position in  FIG. 1 . In this position, push rod  52  is fully retracted in cylinder  50 , and each working arbor  113 ,  114  has its driven feature  129 ,  130  in mating engagement with driving features  94 ,  95  of drive shafts  90 ,  91 . Also, screw drive shaft coupler  84  engages coupling  104  which mechanically connects jackscrews  74  and  106  to equalize vertical shifting of bearing blocks  66  and  109 , if adjustment is required. 
         [0024]    During operation, rotational movement of drive shafts  90 ,  91  rotates vertically spaced adjacent arbors  113 ,  114  and rollers  117 ,  118  that are fixed on their corresponding arbors  113 ,  114 . Sheet steel is passed through the rollers  117 ,  118  to be bent. As shown in  FIG. 5 , successive mill stands in the tube line  10  further shape the steel until it emerges in sealed tube form. The upper motor assembly  140  and lower motor assembly  142  are controlled individually and independently by a controller  152 . The controller  152  allows independent speed and/or torque control of each motor, either by current monitoring, speed monitoring, or an external torque sensor affixed between the motor  144 ,  148  and its respective drive shaft  91 ,  90 . As shown in  FIG. 6 , a monitoring panel  154  controls and displays the torque as supplied by each motor assembly  140 ,  142 . The monitoring panel  154  shows the torque for all of the individual drivers for each station, allowing the user to tailor and balance the load from roller to roller and mill stand to mill stand. An operator can independently control rollers within the same mill stand so that adjacent rollers have different speeds and applied torques. Each mill stand has its own respective display group  156 ,  158  of torque/speed for the upper and lower roller for each mill stand. The torque/speed for the upper roller  160  and the torque/speed for the lower roller  162  are displayed individually, allowing the operator to adjust each roller independently. As is shown in display group  158 , the upper and lower rollers have a higher torque than display group  156 . In this case, the operator can balance the load by increasing the torque for display group  156  and reducing the torque for display group  158 . 
         [0025]    When it is time to change rollers, such as when different wall thickness or pipe diameter is to be run, mill stand  14  need not be removed from the line  10  by crane, as previously required.  FIGS. 2 and 5  illustrate the step of removing mill stand  14  from line  10 . Cylinder push rod  52  is extended, and by virtue of its connection to bracket  54 , frame  42  slides along rails  48 ,  49  in the direction of arrow  134  until the full off-line position is reached as shown. Preferably, the rollers  127 ,  128  (shown in dotted line form in  FIG. 2 , and in solid lines in  FIG. 3 ) are already secured to standby arbors  115 ,  116  (see arrow  136 ) so as to further reduce changeover time and to reduce the downtime of line  10 . 
         [0026]    Arbor frame  96  is then rotated as indicated by arrow  126  to bring the standby arbors  115 ,  116  and rollers  127 ,  128  into the working alignment shown in  FIG. 3 . Cylinder push rod  52  is then retracted to slide arbor frame  96  towards drive frame  60  (arrow  138 ) until driven features  131 ,  132  engage driving features  94 ,  95  as before described. Vertical adjustments are again performed by rotation of jackscrews  74 ,  107 . Rollers  117 ,  118  secured to standby arbors  113 ,  114  may be removed and replaced if necessary. 
         [0027]    The above procedure is carried out for each mill stand along line  10  which requires that different rollers be used. By providing for the shiftable mill stands and rotatable turret heads, changeover and down time is significantly reduced with no loss in accuracy of roller settings. Further, the differential speed control of each of the rollers in the separate mill stands provides tailored control and reduced stress on the drive mechanism. 
         [0028]    It is understood that while certain aspects of the disclosed subject matter have been shown and described, the disclosed subject matter is not limited thereto and encompasses various other embodiments and aspects. No specific limitation with respect to the specific embodiments disclosed herein is intended or should be inferred. Modifications may be made to the disclosed subject matter as set forth in the following claims.

Technology Category: b