When a sheet metal is sandwiched between a punch held by a punch holder and a die held by a die holder to bend the sheet metal at a set bending angle by moving the punch toward the die, a stroke calculation unit calculates a stroke of the punch for bending the sheet metal at the bending angle in consideration of a spring back amount of the bent sheet metal. A bending load calculation unit calculates a bending load required to bend the sheet metal at the bending angle. A punch deflection amount calculation unit calculates a punch deflection amount according to the bending load. A punch holder deflection amount calculation unit calculates a punch holder deflection amount according to the bending load. A depth value calculation unit calculates a depth value by adding at least the punch deflection amount and the punch holder deflection amount to the stroke.

When a sheet metal is sandwiched between a punch held by a punch holder and a die held by a die holder to bend the sheet metal at a set bending angle by moving the punch toward the die, a stroke calculation unit calculates a stroke of the punch for bending the sheet metal at the bending angle in consideration of a spring back amount of the bent sheet metal. A bending load calculation unit calculates a bending load required to bend the sheet metal at the bending angle. A punch deflection amount calculation unit calculates a punch deflection amount according to the bending load. A punch holder deflection amount calculation unit calculates a punch holder deflection amount according to the bending load. A depth value calculation unit calculates a depth value by adding at least the punch deflection amount and the punch holder deflection amount to the stroke.

A precision compensation mechanism of a full-automatic bidirectional flanging machine comprises an upper die X-direction fine adjustment assembly, an upper die Y-direction fine adjustment assembly, a lower die X-direction fine adjustment assembly and a lower die Y-direction fine adjustment assembly, wherein the fine adjustment assemblies each comprise N adjusting threaded sleeves, N adjusting screws and a threaded sleeve rotation driving device; wherein the N adjusting threaded sleeves are threaded into an upper opening or a lower opening of a C-shaped flanging beam along the length direction of an upper die or a lower die; the outer wall surfaces of the N adjusting threaded sleeves are threaded into the upper opening or the lower opening of the C-shaped flanging beam to form N screw thread pairs I with the thread pitch of P1.

A mold holder device in a press brake includes a mold clamp that clamps a mold with respect to a mold contacting surface provided for a holder body of the mold holder device. The mold clamp is pivotally arranged on the holder body. A long groove is formed in a mold clamping surface with which the mold clamp clamps the mold with respect to the mold contacting surface. The long groove is in parallel with a pivot axis of the mold clamp. A metal pipe member has a longitudinal slit and is inserted in a rotation restricted state into the long groove. A part of an outer peripheral surface of the pipe member is protruded toward the mold contacting surface.

A crowning method applied to a press brake including an upper table and a lower table as being vertically opposed to each other and including first slits opened in right and left directions on both right and left sides of the upper table or the lower table, is by deforming end sides of upper portions or lower portions of the first slits of the upper table or the lower table upward or downward to carry out a crowning regulation.

The invention relates to a method for compensating deviations in a deforming operation between two beams of a press, comprising of arranging one or more compensating element at a suitably chosen location in the press, detecting the deviations and moving the compensating element(s) relative to the beams by (electro) mechanical means during the deforming operation such that the detected deviations are compensated. The compensating elements can be moved here to an over-compensating position prior to the deforming operation and pressed out of their over-compensating position during the operation by the load on the beam, wherein each compensating element exerts an adjustable resistance force on surrounding parts of the press. The compensating elements each can be pressed stepwise to a position compensating the detected deviations during the deforming operation. Piezoelectric actuators can be used to exert the resistance force and/or to move the compensating elements.

The invention relates to a method for bending of a workpiece (2) along a straight bending line (27), by means of a first bending tool (5) and a second bending tool (6) of a press brake (3), wherein the region between the two bending tools (5, 6) is monitored for the presence of obstacles by means of a safety system (30), by a control apparatus (24), during the approach movement between the first bending tool (5) and the second bending tool (6). Subsequently, the position of the bending line (27) of the stress-relieved and pre-bent workpiece (2) is determined in relation to a center plane (40) of the first (5) and/or of the second bending tool (6), by means of the safety system (30). On the basis of a control signal, a correction of the position of the workpiece (2) is is carried out, until the position deviation (42) of the bending line (27) lies within a permissible maximal deviation from the center plane (40). Subsequently, the workpiece (2) is bent to its final angle.

A frame structure includes a C-shaped frame having a front side that opens in a forward and rearward direction among the forward and rearward direction, a leftward and rightward direction and an upward and downward direction, which are perpendicular to each other, an upper action section supported by an upper front portion of the C-shaped frame, and a lower action section supported by a lower front portion of the C-shaped frame, wherein, when a reaction force is applied through the upper action section, the C-shaped frame is deformed such that a displacement of the upper action section in the forward and rearward direction, which occurs according to an elastic deformation of the C-shaped frame, is canceled out and such that a displacement of a pivotal movement about a leftward and rightward direction axis of the upper action section is canceled out.

A press brake has a lower table arranged at lower part of left and right side frames, an upper table arranged at upper part of the side frames and facing the lower table, one of the upper and lower tables serving as a ram to be moved vertically, and left and right vertical driving units arranged on the side frames, respectively, to move the ram vertically. Strain detecting sensors are arranged on inner and outer side faces, respectively, of each of the left and right side frames, to detect strain of the side frames in such a way as to cancel horizontal deflection of the side frames and detect vertical deflection thereof.

A bending machine for bending workpieces is disclosed. The bending machine includes a lower beam and an upper beam for forming a workpiece by bending along a bending line. A tool holder for receiving bending tools is provided on the lower beam and each end of the tool holder is associated with a recessed region which is formed in the lower beam overlapping with the respective end. The lower beam includes a central element and at least one side element arranged adjacent to one another in the thickness direction of the lower beam. Recessed regions are provided in the central element and/or in the width direction adjacent to the central element. The lower beam also includes a central region in which, during a bending operation of a workpiece, a force is introduced via the tool holder both into the central element and into the at least one side element.