Abstract:
Roller positioner for tubes comprising: a base structure; two lower support rollers rotating around respective axes positioned on said base structure; and an upper roller antagonist to said two lower support rollers; characterized by comprising a deformable quadrilateral for the movement of said upper roller suited for moving said upper roller along a rectilinear axis by a predetermined distance and then away from said rectilinear axis.

Description:
This application is the national stage of PCT/IB2014/064111, filed Aug. 28, 2014, which claims priority from Italian Application No. BG2013A000026, filed Sep. 4, 2013. 
     FIELD OF INVENTIION 
     The present invention relates to a positioner for tubes, and in particular to a roller positioner for tubes. 
     In the metal framework and boiler factory field it is commonplace the presence of machines suitable for arranging the work-piece in the best position for performing on the same welding and like operations (grinding, cutting etc.). Said machines are therefore called “welding positioners” and are divided into two main to categories. 
     The table positioners, characterized by a work-piece holding table, tiltable, rotating and possibly adjustable in its height from the ground, on whose surface the work-piece is clamped. 
     The roller positioners which are machines used to support cylindrical bodies (tubes) by means of elements each constituted by a crosspiece and two work-piece support rollers. In said case, the only movement of the work-piece is a rotation with respect to its longitudinal axis. 
     BACKGROUND OF THE INVENTION 
     In parallel, in common workshop use, particularly in the field of plumbing, i.e. those companies and/or units specialized in the production of tubes, flanged fittings, manifolds with joints etc. has stimulated the development of another category of positioners which is located, by its type of use and conformation, between the two main categories introduced above. 
     Said solution provides two lower support rollers and one upper “antagonist” roller which by tightening upon the work-piece ensures gripping thereof. The gripping is obtained by way of a fixed support column of the antagonist roller and by an adjusting screw for approaching the roller to the work-piece. 
     The solution is effective but the presence of the counter-roller “in irremovable position” makes the loading and unloading operations of the work-piece uncomfortable, in addition to imposing relatively narrow limits on the diameters of the loadable pieces. 
     SUMMARY OF THE INVENTION 
     Purpose of the present invention is to provide a positioner for tubes provided with an antagonist gripping element which obviates the drawbacks of the known art. 
     Another purpose is to provide an antagonist element suited to allow loading the piece from above without interference of structural elements. 
     A further purpose is to provide a positioner for tubes having reduced transversal structural dimensions suitable to allow loading of work-pieces with curves and/or close joints. 
     Another purpose is to provide a positioner for tubes having swiveling capacity in order to allow tilting of the work-piece. 
     According to the present invention, said purposes and further purposes are achieved by a roller positioner for tubes comprising: a base structure; two lower support rollers rotating around respective axes positioned on said base structure; and an upper roller antagonist to said two lower support rollers; characterized by comprising a deformable quadrilateral for the movement of said upper roller suitable for moving said upper roller along a rectilinear axis by a predetermined distance and then away from said rectilinear axis. 
     Further characteristics of the invention are described in the dependent claims. 
     The advantages of this solution compared to the solutions of the prior art are various. 
     The implementation of an antagonist counter roller with respective “removable” support arm has led to the implementation of a deformable quadrilateral geometry. 
     The antagonist counter roller, in order to properly “grip” the work-piece must be able to maintain itself along the vertical axis that crosses the center or, at least, to deviate to a limited extent from said trajectory. 
     The counter roller is kept, along its vertical stroke, close to the vertical line passing through the rotation center of the loaded work-piece. Once a height corresponding to the maximum gripable diameter is reached, kinematics deviates the motion of the counter roller allowing it to move further away from the vertical trajectory for following a parabola that leads it away from the work area. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING FIGURES 
       The characteristics and advantages of the present invention will become apparent from the following detailed description of a practical embodiment thereof, illustrated by way of a non-limiting example in the accompanying drawings, wherein: 
         FIG. 1  schematically shows a positioner for tubes, according to the present invention; 
         FIG. 2  schematically shows part of the kinematic mechanisms of a positioner for tubes, according to the present invention; 
         FIGS. 3   a,    3   b,    3   c  and  3   d  show schematically the movements of a deformable quadrilateral of a positioner for tubes, according to the present invention; 
         FIG. 4  schematically shows the fine adjustment of the counter roller of a positioner for tubes, according to the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to the attached figures, a positioner for tubes, according to the present invention, comprises a positioner support structure  10 . The structure is composed by a base  11  and by two vertical wings  12 . 
     To the two wings  12  a swiveling container  13  is hinged so as to be movable. The container  13  can then be tilted and fixed in said position by way of adjusting and fixing means  14 . 
     The container  13  is composed of two lateral substantially L-shaped walls, closed by two rectangular walls. 
     Located inside the container  13  are the kinematic mechanisms of the positioner. 
     Two support rollers  20  are rotatable around horizontal pins positioned on the horizontal L-shaped portion of the container  13 . The rollers  20  are operable in a known manner by means of motors and controls not shown. 
     Positioned above the support roller  20  is the tube  21  to be worked. 
     As known, opposed to the support rollers  20  is necessary an upper “antagonist” roller or counter roller  22  that by tightening upon the tube  20 , in association with the rollers  20 , ensures gripping. 
     The kinematic mechanisms  23  for moving the counter roller  22 , which are obtained by way of a deformable quadrilateral, are arranged mainly in the vertical portion of the L-shape of the container  13 . 
     The kinematic mechanisms  23  comprise a lower connecting rod  25 , which for locking reasons of the kinematic mechanisms  23  themselves, has substantially the shape of a circular sector. 
     The lower connecting rod  25  has a pin  26  arranged at the center of the circular sector forming the lower connecting rod  25 , and a plurality of holes  27  along the arc of the circular sector. 
     The lower connecting rod  25  can then rotate around the pin  26  with respect to the vertical portion of the L-shape of the container  13 . 
     Furthermore it has a pin  28  arranged at the upper end of the circular sector arc forming the lower connecting rod  25 . 
     The pin  28  also passes through a hole in a bottom corner (left) of an oscillating arm  29 , having a substantially rectangular shape, with the lower side (with respect to  FIG. 2 ) recessed inwards leaving space for other kinematic mechanisms. 
     In the upper corner (left with respect to  FIG. 2 ) of the oscillating arm  29 , in the proximity of the pin  28 , there is another pin  30  connected to an upper connecting rod  31  having at the other end, a pin  32  connected to the upper vertical part of the L shape of the container  13 . 
     The pins  32  and  26  are attached on the container  13 , and therefore are fixed. 
     The pin  28  is fixed between the lower connecting rod  25  and the oscillating arm  29 . The pin  30  is fixed between the oscillating arm  29  and the upper connecting rod  31 . Therefore these two pins  28  and  30  move freely and are not connected to fixed structures. 
     Comprised on the lower corner (right) of the swinging arm  29  there is a pin  40  around which an arm  41  can rotate on whose end the counter roller  22  is arranged. 
     The pin  40  is arranged substantially at the center of the arm  41 . 
     The arm  41 , at the opposite end of the counter roller  22  is hinged on the pin  39  with the end of a threaded bar  42 . On the oscillating arm  29  in its upper corner  43  (right), an internally threaded bushing  44  is pivoted, in which the bar  42  passes through. Above the bushing  44 , the bar  42  comprises a hand wheel  45 . 
     By maneuvering the hand wheel  45 , the arm  41  is made to rotate around the pin  40  and the counter roller  22  can perform an upwards or downwards arc. 
     The movement of the kinematic mechanism is assisted by a gas spring  38  connected between the container  13  and the lower connecting rod  25 . 
     The operation of the invention appears evident to the skilled in the art from what has been described and, in particular, is the following. 
     In  FIG. 3 a    the working position is shown, i.e. when the counter roller  22  is placed over the tube  21 , and the pins  26  and  28 , of the lower connecting rod  25 , are substantially horizontal, like the oscillating arm  29  and the arm  41 . The upper connecting rod  31  is inclined downwards from pin  32  by about 45°. 
     In particular, note the position of the pin  40  that lies along a vertical axis  46 . 
     The pin  40  supports the arm  41 , fixed in position by the hand wheel  45 , which will move accordingly, and therefore the counter roller  22  will move with a movement similar to that of the pin  40 . 
     By pushing upwards the pin  40 , the oscillating arm  29  is raised, which rotates around an instantaneous rotation center (I.R.C) which is arranged at the junction of two lines. The first rectilinear line  50  passes through the pins  30  and  32  of the upper connecting rod  31 . The second rectilinear line  51  passes through the pins  26  and  28  of the lower connecting rod  25 . 
     The oscillating arm  29  continues to rotate around the instantaneous rotation center, until reaching the position shown in  FIG. 3   c,  keeping the pin  40  (and consequently the counter roller  22 ) always on a trajectory along the vertical axis  46 . 
     Therefore, the movement of the pin  40  is similar to a translation motion. 
     As can be seen from  FIG. 3 c    the instantaneous rotation center is located practically in the position of the pin  30 , and advancing in motion, it follows a reversal of the rotation direction of the connecting rod  31 , and therefore from this point on the movement proceeds with rotation movement clockwise and concordant with the two connecting rods  25  and  31  of the articulated quadrilateral, moving the pin  40  away from the axis  46 . 
     The arm  29  initially assumes a rotary motion around the pin  30 , which causes it to diverge rapidly from the working area. 
     The reversal of the rotation direction of the connecting rod  31  leads to a distortion of the articulated quadrilateral, the instantaneous rotation center moves gradually towards the pin  32  and the arm  29  reaches the end of stroke with the connecting rod  31  contacting the circular sector of the lower connecting rod  25 . 
     During the movement of the kinematic mechanism, and in particular during the movement of the pin  40  along the axis  46 , it is possible to lock it in the desired position by inserting a pin  55  in one of the holes  27 , which will correspond to a locking hole on the container  13 . 
     For the use of the roller positioner for tubes, according to the present invention, the kinematic mechanism is completely raised taking the counter roller  22  laterally and away from the intermediate axis to the support rollers  20 . 
     For safety, the pin  55  is inserted in one of the holes  27  for locking the structure. 
     In this way ample space is left for positioning the tube  21 . 
     With said arrangement it is possible to lower the tube  21  from above and place it comfortably on the support rollers  20 , by means of a winch or other lifting means. 
     The pin  55  is unlocked and the counter roller  22  is lowered into position above the tube  21 . 
     Once the position is found, the pin  55  is again locked by inserting it in the most suitable hole for the purpose. 
     Since this is a discrete adjustment dictated by the positioning to of the holes  27 , it could happen that the counter roller is not properly placed over the tube  21 . 
     Therefore, a fine adjustment of the positioning of the counter roller  22  can be performed by way of the hand wheel  45 , which by lifting the pin  39  rotates the arm  41  around the pin  40  and pushes the counter roller  22  against the tube  21 . 
     The movement of the kinematic mechanism described above is manual but the use of automatic handling means is possible. 
     Both manual and automatic alternative moving and locking methods of the kinematic mechanisms described above may also be used. 
     For example it is possible to arrange a motorized or manually operated worm screw acting on the lower connecting rod  25 . 
     Or, it is possible to use a toothed sector integral with the lower connecting rod  25  and engaging on a worm reduction gear pinion. 
     Alternatively, the counter roller  22  could be fixed directly to the pin  40  of the oscillating arm  29 , and a finer fixing adjustment than that obtained with the holes  27  on the lower connecting rod  25  can be provided, obtaining the same results of the above solution. 
     The materials used, as well as the dimensions, may be any according to requirements, size and weight of the tubes being worked, and to the state of the art. 
     The positioner thus conceived is subject to numerous modifications and variations, all falling within the inventive concept; moreover, all details are replaceable by technically equivalent elements.