Apparatus and method for bending bars

Abstract

The apparatus for bending bars includes a bending unit suitable for receiving on a work surface (α) at least one bar according to a longitudinal direction (A), and a bending head which can be engaged on the bending unit, at a bending axis (B). The bending head includes a bending mandrel and an eccentric pin rotatable on the work surface (α) around the bending axis (B), to bend the bar around the mandrel.

1 . An apparatus for bending bars, in particular metal bars, comprising at least one bending unit adapted to receive at least one said bar on a work surface (α) according to a longitudinal direction (A), and a bending head which can be engaged on said bending unit, at a bending axis (B), said bending head comprising a bending mandrel and an eccentric pin, rotatable on said work surface (α) around said bending axis (B), to bend said bar around said mandrel, and a conveying device comprising an articulated arm constrained to a height below said work surface (α) and a gripping member articulated to said articulated arm at an orientation axis, said gripping member being movable between an open configuration for releasing and a closed configuration for holding, characterized in that said bending head comprises a gripping portion configured to be held by said gripping member arranged in said closed configuration and in that said transfer device is movable with a replacement motion between a first position in which said gripping member is arranged in a closed configuration at said bending head mounted on said bending unit, to hold said gripping portion, and a second raised position, in which said bending head held by said gripping member is drawn out from said work surface (α). 
     
     
         2 . The apparatus of  claim 1 , further comprising a magazine having at least one containment seat for said bending head, said transfer device being movable in said replacement motion from said second position to a third position in which said gripping member is arranged at said magazine to release said bending head in said containment seat. 
     
     
         3 . The apparatus of  claim 2 , wherein said magazine comprises a plurality of containment seats for as many spare bending heads, said transfer device being movable to take or insert said spare bending head. 
     
     
         4 . The apparatus of  claim 2 , wherein said magazine extends parallel to said longitudinal direction (A), being interposed between said feeding station and said bending unit. 
     
     
         5 . The apparatus of  claim 1 , wherein said gripping portion is made by means of a handle projecting transversely from said mandrel. 
     
     
         6 . The apparatus of  claim 5 , wherein said gripping portion has at least one recess configured to be engaged by said gripping member. 
     
     
         7 . The apparatus of  claim 6 , wherein said gripping portion comprises a pair of recesses separated by a rib shaped to be held by said gripping member in said closed configuration. 
     
     
         8 . The apparatus of  claim 1 , wherein said gripping portion is obtained at least partially from a portion of said mandrel, opposite to said eccentric pin. 
     
     
         9 . The apparatus of  claim 1 , wherein said bending assembly comprises an eccentric housing for housing said gripping portion, when said bending head is engaged on said bending unit, shaped so that said gripping portion is substantially underneath said work surface (α) when said bending head is engaged on said bending unit. 
     
     
         10 . The apparatus of  claim 9 , wherein said eccentric housing is selectively orientable with respect to said bending axis (B) according to a collecting orientation, at which said gripping portion is oriented to be held by said gripping member in said first position. 
     
     
         11 . The apparatus of  claim 1 , wherein said gripping member is a jaw member, configured to engage said gripping portion. 
     
     
         12 . The apparatus of  claim 1 , wherein said gripping member and said gripping portion have an at least partially conjugate sectional profile. 
     
     
         13 . The apparatus of  claim 1 , wherein said transfer device is configured to hold one or more said bars in said closed configuration, being also movable with a transfer motion to transfer said retained bars from and/or to said bending unit. 
     
     
         14 . The apparatus of  claim 1 , wherein said articulated arm of said transfer device is constrained in a position between the dimensions of said bending unit and the dimensions of a feeding station arranged upstream, serving said bending unit to feed said bars therein. 
     
     
         15 . A method for bending bars, in particular metal bars, comprising the steps of
 a. arranging a bending unit equipped with a bending head and at least one transfer device equipped with an articulated arm and a gripping member, articulated to said articulated arm;   b. carrying out a bending cycle of a number of bars on said bending unit and unloading said number of bent bars from said bending unit;   c. grasping with said gripping member a gripping portion of said bending head;   d. operating said transfer device in a replacement motion to draw out said bending head from said bending unit and transferring it to a magazine associated with said bending unit;   e. operating said gripping member to release said bending head in an empty position of said magazine;   f. moving said transfer device relative to said magazine to reach a position of magazine where a spare bending head is placed;   g. grasping said respective gripping portion of said spare bending head with said gripping member;   h. moving said conveying device to take from said magazine said spare bending head, transfer and engage it into said bending unit.   
     
     
         16 . The method of  claim 15 , further comprising operating said transfer device in a transfer motion to grasp said bars and load them onto said bending unit and/or to unload said bent bars from said bending unit.