An electronic angle measuring device for measuring the bending angle between the legs (4) of a metal sheet (5) having a sensor element (7) which delivers angle-equivalent signals in a contact-free manner to a signal processing device (9) comprising a microprocessor and a memory unit which is connected to a digital display (10) is described. In order to create advantageous measurement conditions, it is proposed that a sensor element (7) which deflects a laser beam through a rotating mirror onto the two legs (4) of the metal sheet (5) and which forms a measured value from the reflection beam received in the emission direction, the signal processing device (9) with the microprocessor and the memory unit as well as the digital display (10) form an angle measuring device (6) which can be fastened to an upper tool (1) of a bending machine and which can be used as a manual measuring device (6).

Two press brake machines each using a single, central hydraulic actuator are provided. The press brake machines are configured to operate separately or in tandem, depending upon a size of a sheet metal workpiece to be deformed. A locking device that may include an upper connecting block and a lower connecting block is provided on each of the at least two press brake machines to allow the machines to interlock when the machines are adjacent to one another and are operating in tandem. The upper connecting block may be L shaped to help provide the interlocking. Interlocking of the press brake machines during tandem operation helps prevent distortion that can occur in the upper and lower portions of the ram due to the press brake machine's use of a single, central hydraulic actuator.

An electronic angle measuring device for a bending machine for measuring the bending angle between the legs (4) of a sheet (5) using a sensor element (7) is described, which supplies angle-equivalent signals in a contactless manner to a signal processing unit (9), which has a microprocessor and a memory unit and is connected to a digital display (10). To provide simple measuring conditions, it is proposed that the sensor element (7), the signal processing unit (9), and the display (10) form an angle measuring device (6) which is fastenable on the upper tool (1) of the bending machine and is usable as a handheld encoder, and which has a motion sensor (11), which is connected to the signal processing unit (9) and detects the lowering and/or raising movement of the upper tool (1), for triggering the measuring procedure

A bending machine includes hydraulic cylinders capable of adjusting an inclination state, eccentric shaft units, and a control device. The control device sets an inclination state of the upper table and also sets a curved state of the lower table to conform to the inclination state of the upper table in order to carry out partial bending to pressurize a limited pressurized range compared to a pressurized range in which a workpiece is pressurized by using entire areas of an upper tool and a lower tool in a lateral direction. The control device changes a combination of the inclination state of the upper table and the curved state of the lower table and repeats the partial bending while causing a transition of the limited pressurized range in order to carry out entire area bending to pressurize the workpiece over an entire area in the lateral direction.

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.

It is conversely possible for the compensating elements each to be pressed stepwise to a position compensating the detected deviations during the deforming operation.

It is possible to use (piezoelectric) actuators to exert the resistance force and/or to move the compensating elements.

The invention further relates to a device with which this compensation method can be performed.

There is provided a press brake that improves bending accuracy of a partial bending method. The press brake includes: a conveying mechanism that intermittently conveys a workpiece; a die; a punch; a crowning mechanism; a bending amount measuring device; and a control device. The control device presses an end portion of the workpiece in a conveying direction by the punch and conveys the workpiece by the conveying mechanism until the pressed portion enters into a measurement range of the bending amount measuring device. The control device drives the crowning mechanism so as to correct a crowning amount in accordance with a difference between a middle bending amount and an end bending amount measured by the bending amount measuring device.

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 press brake is equipped with an upper table provided so as to be vertically movable at an upper part of a main frame and holding a punch tool on a lower side thereof, and a lower table provided at a lower part of the main frame and holding a die tool on an upper side thereof. A pair of slits extending symmetrically in a lateral direction are formed in the lower table, and an end portion of each slit on an outer side in the lateral direction is opened. An elastic member is provided in the end portion of each slit on the outer side in the lateral direction. The elastic member is configured to be switchable between a load-receiving state for receiving a bending load acting on the lower table and a released state in which the load-receiving state has been released.

A drive system for a machine tool comprises two, at least equally long drive spindles, extending parallel to each other and being structurally identical with regard to their torsional rigidity and their axial rigidity, which are each supported to rotate about a spindle axis, and which can be driven about the spindle axis concerned. Each of the drive spindles has a fixed bearing at one end, acting in its longitudinal direction. Spindle nuts, which are seated on the drive spindles can be moved simultaneously with longitudinal movements in the longitudinal direction of the drive spindles.