A flat heat transfer tube is used for a cross fin tube type heat exchanger including the flat heat transfer tube having a bending portion and a plurality of holes extending in a direction parallel with an axis direction of the flat heat transfer tube, and a plurality of plate fins bonded by welding to the flat heat transfer tube, wherein an interval between an outer surface of the flat heat transfer tube and an inner surface of the hole of a portion which is curved with a small curvature during bending is larger than an interval between an outer surface of the flat heat transfer tube and an inner surface of the hole of a portion which is curved with a large curvature during bending in a cross section of a portion of the flat heat transfer tube which corresponds to the bending portion before bending.

The invention relates to a bending head, especially for an automatic bending machine, containing a pair of bending rolls (1, 2) and a bending support (3), whereby below the first bending roll (1) is arranged transversely on the bending head a bending arm (20), which is positioned with its longitudinal axis perpendicularly to the longitudinal axis of the first bending roll (1), the bending arm (20) is mounted on the bending head with one of its ends rotatably about the longitudinal axis of the first bending roll (1) and is coupled to a drive, while at the other end of the bending arm (20) is mounted rotatably about its longitudinal axis the second bending roll (2), whose longitudinal axis is parallel to the longitudinal axis of the first bending roll (1). The second bending roll (2) is coupled to the first bending roll (1) with the aid of means of forced torque transmission, whereby both rolls (1, 2) are provided with mutually axially symmetrical lightweight sections (X) of their circumferences, the first bending roll (1) is coupled to a drive of its rotary motion with a controlled angle of rotation and the bending arm (20) is coupled to a drive of bidirectional bending, whereby the bending support (3) is formed by a bending support for bidirectional bending.

The invention relates to a bending head, especially for an automatic bending machine, containing a pair of bending rolls (1, 2) and a bending support (3), whereby below the first bending roll (1) is arranged transversely on the bending head a bending arm (20), which is positioned with its longitudinal axis perpendicularly to the longitudinal axis of the first bending roll (1), the bending arm (20) is mounted on the bending head with one of its ends rotatably about the longitudinal axis of the first bending roll (1) and is coupled to a drive, while at the other end of the bending arm (20) is mounted rotatably about its longitudinal axis the second bending roll (2), whose longitudinal axis is parallel to the longitudinal axis of the first bending roll (1). The second bending roll (2) is coupled to the first bending roll (1) with the aid of means of forced torque transmission, whereby both rolls (1, 2) are provided with mutually axially symmetrical lightweight sections (X) of their circumferences, the first bending roll (1) is coupled to a drive of its rotary motion with a controlled angle of rotation and the bending arm (20) is coupled to a drive of bidirectional bending, whereby the bending support (3) is formed by a bending support for bidirectional bending.

A roll bending apparatus includes: a roll pair formed by a pair of rolls disposed facing each other, the roll pair being configured to sandwich an elongated material between the rolls to perform forming on the elongated material; a slide mechanism configured to slide the roll pair in a first normal direction that is a direction normal to a conveying direction of the elongated material on a plane including the conveying direction; and a tilt mechanism configured to rotate the roll pair about a tilt axis that extends in a second normal direction that is a direction orthogonal to the conveying direction and the first normal direction. The slide mechanism further slides the roll pair to change a position of the roll pair relative to the tilt axis.

A roll bending apparatus includes: a roll pair formed by a pair of rolls disposed facing each other, the roll pair being configured to sandwich an elongated material between the rolls to perform forming on the elongated material; a slide mechanism configured to slide the roll pair in a first normal direction that is a direction normal to a conveying direction of the elongated material on a plane including the conveying direction; and a tilt mechanism configured to rotate the roll pair about a tilt axis that extends in a second normal direction that is a direction orthogonal to the conveying direction and the first normal direction. The slide mechanism further slides the roll pair to change a position of the roll pair relative to the tilt axis.

A method for obtaining a three-dimensional curve in a tubular product starting from a tube extending along a rectilinear longitudinal axis includes performing, by a first bending device, a first bending operation on a bending plane passing through the rectilinear longitudinal axis (x), so that the tube leaving the first bending device has a curved portion lying on the plane of curvature, and performing on the tube leaving the first bending device, by a second bending device, a second bending operation, so that the curved portion of the tube at the output of the second bending device has a first tangent and a second tangent (t1, t2) at its opposite ends lying on a cylindrical surface having generatrices orthogonal to two planes (A1, A2) respectively containing the first and second tangents (t1, t2). A method for manufacturing complex-curvature tubular products is also provided.

A single bending device for continuous three-dimensional bending has a rotating and feeding holder for holding a workpiece, a bending roller assembly having multiple rollers being different in radius, a pressing roller head for bending the workpiece. The bending roller assembly can be moved to allow one predetermined roller to abut against the workpiece. Then the workpiece can be bent by the pressing roller head pushing the workpiece along the predetermined roller. Thus, as long as a different one of the rollers corresponds in position to the workpiece, a bending portion having a different curvature can be formed on the workpiece. Moreover, by controlling the moving length of the pressing roller head along the workpiece, the arc length of each bending portion of the workpiece can be controlled accordingly. It is not necessary to replace the jigs and the dies repeatedly.

A single bending device for continuous three-dimensional bending has a rotating and feeding holder for holding a workpiece, a bending roller assembly having multiple rollers being different in radius, a pressing roller head for bending the workpiece. The bending roller assembly can be moved to allow one predetermined roller to abut against the workpiece. Then the workpiece can be bent by the pressing roller head pushing the workpiece along the predetermined roller. Thus, as long as a different one of the rollers corresponds in position to the workpiece, a bending portion having a different curvature can be formed on the workpiece. Moreover, by controlling the moving length of the pressing roller head along the workpiece, the arc length of each bending portion of the workpiece can be controlled accordingly. It is not necessary to replace the jigs and the dies repeatedly.

The invention relates to a bending machine (M) for bending a workpiece (300), remarkable in that a clamping jaw (511) is supported by a clamping jaw holder (510) receiving at least two clamping jaws (511, 512) arranged back to back, the clamping jaw holder (510) being fastened to a shelf (513) guided and driven in translation on the bending arm (500), the support shelves (600) punctually receiving the clamping jaw holder (510) separated from the shelf (513) and to move it on either side of the bending axis transversely to the advance axis of the workpiece (300) to be bent, independently of the bending arm (500) so that the clamping jaw holder (510) can be fastened again to the shelf (513) once the bending arm (500) has been rotated 180 degrees. The invention also relates to a bending process.

The invention relates to a bending machine (M) for bending a workpiece (300), remarkable in that a clamping jaw (511) is supported by a clamping jaw holder (510) receiving at least two clamping jaws (511, 512) arranged back to back, the clamping jaw holder (510) being fastened to a shelf (513) guided and driven in translation on the bending arm (500), the support shelves (600) punctually receiving the clamping jaw holder (510) separated from the shelf (513) and to move it on either side of the bending axis transversely to the advance axis of the workpiece (300) to be bent, independently of the bending arm (500) so that the clamping jaw holder (510) can be fastened again to the shelf (513) once the bending arm (500) has been rotated 180 degrees. The invention also relates to a bending process.