Abstract: 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.

Abstract: 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.

Abstract: According to a laser cutting method, a processed part is laser-cut so that the processed part doesn't drop off from a sheet-shaped workpiece. In the laser cutting method, a cut slit of a pressing protrusion, which is curved due to a laser cutting process along an outline of the processed part and then presses a peripheral surface of the processed part, is preliminarily formed around the processed part to be cut out from the workpiece. Then, the laser cutting process is carried out along the outline of the processed part. The pressing protrusion curves toward the processed part due to the laser cutting process of the processed part, and then the processed part is retained by the pressing protrusion.

Abstract: According to a laser cutting method, a processed part is laser-cut so that the processed part doesn't drop off from a sheet-shaped workpiece. In the laser cutting method, a cut slit of a pressing protrusion, which is curved due to a laser cutting process along an outline of the processed part and then presses a peripheral surface of the processed part, is preliminarily formed around the processed part to be cut out from the workpiece. Then, the laser cutting process is carried out along the outline of the processed part. The pressing protrusion curves toward the processed part due to the laser cutting process of the processed part, and then the processed part is retained by the pressing protrusion.

Abstract: A method for bending a flat workpiece is provided. The method may include applying heat or pressure to the workpiece at a range within a first width from an edge with a residual stress formed by cutting so as to reduce the residual stress, and bending the workpiece along a bending line after applying the heat or pressure.

Abstract: A device for regulating a residual stress is comprised of: input means; a residual stress database; a process condition database; first searching means for searching a residual stress (?0) from the residual stress database; a calculator for calculating a first bending moment (Mrs) in a ridge line originated from the residual stress, and a second bending moment (Mz) in the ridge line originated from bending to obtain a total bending moment (Mrs?Mz) and calculating a camber curvature (?z) of the workpiece originated from the total bending moment (Mrs?Mz); comparing a difference (|?z??z0|) between the camber curvature (?z) and a target value (?z0) with a tolerable value (?); second searching means for searching a process condition satisfying a tolerable condition (|?z??z0|??) from the process condition database when (|?z??z0|>?); and regulating means for regulating a residual stress.

Abstract: A device for regulating a residual stress is comprised of: input means; a residual stress database; a process condition database; first searching means for searching a residual stress (?0) from the residual stress database; a calculator for calculating a first bending moment (Mrs) in a ridge line originated from the residual stress, and a second bending moment (Mz) in the ridge line originated from bending to obtain a total bending moment (Mrs?Mz) and calculating a camber curvature (?z) of the workpiece originated from the total bending moment (Mrs?Mz); comparing a difference (|?z??z0|) between the camber curvature (?z) and a target value (?z0) with a tolerable value (?); second searching means for searching a process condition satisfying a tolerable condition (|?z??z0|??) from the process condition database when (|?z??z0|>?); and regulating means for regulating a residual stress.

Abstract: An actual plate thickness and actual material constants are measured during punching before bending. The measured information is reflected on the bending, so that the bending is performed efficiently and accurately. Punching is carried out for each blank developed based on a nominal plate thickness and nominal material constants in blanking before the bending of a work W. Then, an actual plate thickness distribution and an actual material constant distribution of the work W are calculated based on various data containing a ram stroke and a pressure detected in the punching.

Abstract: In bending a workpiece, a position of the workpiece relatively pressed down by a punch is directly detected by a plurality of position detectors provided in a V-groove of a die, and a bending speed calculation section obtains a bending speed from a change in this position. If bending speeds at position of the respective position detectors differ, a uniform speed arithmetic operation section calculates a bending speed to make the bending speeds at the positions of all of the position detectors, and a driving shaft instruction section controls driving shafts to bend the workpiece at the uniform bending speed.

Abstract: A bending method includes determining a provisional bending stroke value that resulted in a predetermined angle during test bending. The bending method also includes calculating a stroke value correction amount for correcting the provisional bending stroke value, based on the number of times a test piece was contacted to obtain the predetermined angle during test bending. The stroke value correction amount is added to the provisional stroke value to obtain a corrected stroke value, so as to obtain the predetermined angle during operational bending using the corrected stroke value.

Abstract: A bending apparatus for bending a workpiece W according to cooperation of a punch P and a die D previously carries out various step bending or makes simulation of step bending, and calculates an approximation formula based on a correlation between a ratio % of a one-sided elongation value &agr; to a plate thickness t and a step bending angle &thgr; based on a relationship among the plate thickness t, the step bending angle &thgr; and the one-sided elongation value &agr; of the workpiece W so as to store the formula as a database. The more accurate one-sided elongation value &agr; of the step bending is calculated by small parameters including only two data including the plate thickness t and the step bending angle &thgr; previously input at the time of actual bending based on the approximation formula in the data base so that the bending is carried out easily.

Abstract: A plate thickness detector for a bending machine causes a punch to make a relative stroke and bend a workpiece mounted on an upper surface of a die cooperatively by the punch and the die. A displacement gauge is provided in the die, is always urged upward from a V-groove of the die, and measures a distance from the upper surface of the die to a lower surface of the workpiece. A ram position detector detects a relative stroke quantity of the punch to the die. The punch is caused to bend the workpiece from a position away from the die by a reference inter-blade distance.

Abstract: A bending apparatus for bending a workpiece W according to cooperation of a punch P and a die D previously carries out various step bending or makes simulation of step bending, and calculates an approximation formula based on a correlation between a ratio % of a one-sided elongation value &agr; to a plate thickness t and a step bending angle &thgr; based on a relationship among the plate thickness t, the step bending angle &thgr; and the one-sided elongation value &agr; of the workpiece W so as to store the formula as a database. The more accurate one-sided elongation value &agr; of the step bending is calculated by small parameters including only two data including the plate thickness t and the step bending angle &thgr; previously input at the time of actual bending based on the approximation formula in the data base so that the bending is carried out easily.

Abstract: An actual plate thickness and actual material constants are measured during punching before bending. The measured information is reflected on the bending, so that the bending is performed efficiently and accurately. Punching is carried out for each blank developed based on a nominal plate thickness and nominal material constants in blanking before the bending of a work W. Then, an actual plate thickness distribution and an actual material constant distribution of the work W are calculated based on various data containing a ram stroke and a pressure detected in the punching.

Abstract: At a time of executing a bending process of a work according to a cooperation between a punch and a die, a provisional stroke value for obtaining a predetermined angle is determined on the basis of a bending process condition. A test bending process is executed on the basis of the provisional stroke value, and a striking number required for striking the work until the predetermined angle is obtained is judged. Since a stroke value correction amount at a time of a main bending corresponding to the striking number and the predetermined angle is previously determined, a main bending process is executed by correcting to a stroke value at a time of the main bending by computing the corresponding stroke value correction amount on the basis of the stroke value correction amount at a time of the main bending process.

Abstract: In a plate thickness detector for a bending machine causing a punch to make a relative stroke and bending a workpiece mounted on an upper surface of a die cooperatively by the punch and the die, a displacement gauge (17) is provided in the die, is always urged upward from a V-groove of the die, and measures a distance from the upper surface of the die to a lower surface of the workpiece, and ram position detection means (11) detects a relative stroke quantity of the punch to the die. The punch is caused to bend the workpiece from a position away from the die by a reference inter-blade distance.

Abstract: In bending a workpiece (W), a position of the workpiece W relatively pressed down by a punch (P) is directly detected by a plurality of position detection means (RDC1, RDC2 and RDC3) provided in a V-groove (11) of a die, and a bending speed calculation section obtains a bending speed from a change in this position. If bending speeds at position of the respective position detection means differ, a uniform speed arithmetic operation section calculates a bending speed to make the bending speeds at the positions of all of the position detection means uniform, and a driving shaft instruction section controls driving shafts (7L, 7R) to bend the workpiece at the uniform bending speed.

Abstract: The low noise punch tool (17) of this invention includes an upper surface pad (51) formed of a low noise material and disposed on an upper surface of a punch head (37) to be struck by a striker (25) of a punch press. Further, an elastic member (55) formed of a low noise material is interposed between the punch head (37) and a punch guide (43), and a ring (53) formed of a low noise material is interposed between the punch body (39, 41) and the punch guide (43). The low noise punch tool (17) includes a lower surface pad (63) formed of a low noise material and attached to a lower surface of a stripper plate (45) provided at a lower end of the punch guide (43). The low noise material may be urethane. Yet further, the cutting edge (41a) provided at the lower end of the punch body (41) has preferably a shearing angle. This punch tool is advantageous in that the noises of the punch tool during punching is significantly reduced, and the structure thereof is simple.