JP2013180339A - Press brake and workpiece bending method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To apply accurate bending to a workpiece, while correcting a springback amount and a crowning amount of the workpiece, with a simple configuration using one bending angle measuring device.SOLUTION: A press brake 1 is configured as follows: a temporary bending D-value for applying temporary bending to a workpiece by using bending conditions of the workpiece W is computed; the temporary bending is applied to the workpiece W by means of the computed temporary bending D-value; a temporary bending angle during pressurization is measured in a state in which the temporary bending is applied; the temporary bending angle during the unloading of the workpiece W is measured after the measurement of the temporary bending angle during the pressurization; and a true D-value for being used to apply permanent bending to the workpiece W and a correction amount in crowning are computed by means of these measurement values to apply the bending to the workpiece W.

Description

  The present invention relates to a press brake and a workpiece bending method, and more particularly to a method of bending a workpiece while correcting a springback amount and crowning according to a measurement result of a workpiece bending angle.

  Conventionally, when bending a workpiece (a workpiece made of metal such as steel or aluminum), the workpiece is measured at the target angle (true bending angle) while measuring the bending angle of the workpiece using an angle sensor (bending angle measuring device). ) Is bent. When this bending process is performed, the amount of spring back of the workpiece is obtained, and the bending process is performed using the obtained amount of spring back. That is, in-line spring back removal is performed (the amount of spring back is acquired in-line and the angle of the spring back is corrected to bend the workpiece).

  Note that the workpiece before bending is formed in, for example, a rectangular flat plate shape, and a bending line in the bending extends in the longitudinal direction of the workpiece and is positioned at an intermediate portion in the width direction of the workpiece.

  Further, when the dimension in the longitudinal direction of a workpiece (for example, a workpiece having a thickness of about 0.5 mm to 4.5 mm) is small (in the case of 300 mm or less), one place such as a central portion in the longitudinal direction of the workpiece is provided. The workpiece is bent by online springback measurement using an angle sensor. And about the workpiece | work with a small dimension of a longitudinal direction, the substantially exact bending angle (bending angle with an error of +/- 15 ') is obtained.

  On the other hand, as shown in FIG. 10, when the dimension of the workpiece W is large (when it exceeds 300 mm), the thickness variation or hardness variation of the workpiece W (material) Slight variations in thickness, etc.) correction errors in table bending in bending machines (for example, correction errors due to crowning), variations in the form of molds such as punches and dies (for example, variations in differences in mold parts) ), The passage cannot be made under the influence of variations in the height of the die holder such as a punch holder or die holder.

  That is, when the workpiece W is long, if the workpiece W is bent while measuring one position such as the central portion in the longitudinal direction of the workpiece W with the angle sensor 201, the bending angle of the workpiece W is It will vary depending on the site of W. For example, when the target bending angle of the workpiece W is 90.0 °, the angle after bending the workpiece W is 89.0 ° at one end in the longitudinal direction of the workpiece W as shown in FIG. The angle after bending of the workpiece W is 90.0 ° at the center portion in the longitudinal direction of the workpiece W, and the angle after bending of the workpiece is 91.degree. At the other end portion in the longitudinal direction of the workpiece W. It will be 0 °.

  Such an adverse effect becomes more prominent when the length of the workpiece is 500 mm or longer.

  Therefore, a plurality of angle sensors 201 are arranged (for example, as shown by broken lines in FIG. 10A, arranged at both ends in the longitudinal direction of the workpiece, or at both ends and the center in the longitudinal direction of the workpiece. ), A method of bending the workpiece W by acquiring the amount of spring back in-line and correcting the angle of the spring back is employed.

  For example, Patent Document 1 can be cited as a document related to the prior art.

Japanese Patent No. 3797718

  However, in the above-described conventional bending of a workpiece, a plurality of angle sensors are required, which causes a problem that the structure of the apparatus becomes complicated.

  The present invention has been made in view of the above problems, and has a simple configuration using one bending angle measuring device (a pair of angle sensors), and the springback amount and crowning of a workpiece (particularly a long workpiece). An object of the present invention is to provide a press brake and a workpiece bending method capable of accurately bending the workpiece while correcting the amount.

  The invention according to claim 1 is the first mold installation body in which the first mold is installed in a press brake that bends a plate-shaped workpiece using the first mold and the second mold. And a second mold installation body that can be moved and positioned relative to the first mold installation body in a direction in which the second mold is installed and approaches or separates from the first mold installation body. A crowning device for crowning the first mold installation body, a bending angle measuring device for measuring a bending angle of the workpiece, a bending angle measuring device moving and positioning device for moving and positioning the bending angle measuring device, An input unit for inputting a bending condition of the workpiece including a true bending angle of the workpiece, and a D value for temporary bending for temporarily bending the workpiece using the bending condition of the workpiece input in the input unit are calculated. The calculated D value for provisional bending Using the first mold installed on the first mold installation body and the second mold installed on the second mold installation body, the workpiece is temporarily bent, The temporary bending angle at the time of pressurization at the first predetermined portion of the workpiece is measured by the bending angle measuring device in a state where the temporary bending process is performed, and the temporary bending process is performed after the measurement of the temporary bending angle at the time of pressurization. In the state of unloading and unloading, the temporary bending angle at unloading at the first predetermined portion of the workpiece and the temporary bending angle at unloading at the second predetermined portion of the workpiece The bending angle measuring device is moved and positioned by the bending angle measuring device moving positioning device, and the measured temporary bending angle at the time of pressurization at the first predetermined portion of the workpiece and the measured first of the workpiece are measured. 1 and a temporary bending angle at the time of unloading at a predetermined portion of the workpiece Used to perform a main bending process on the workpiece using the true bending angle input at the input unit, the calculated spring back amount, and the measured temporary bending angle during unloading. A true D value and a correction amount in the crowning device are calculated, and the installed first mold and the installed second are calculated using the calculated true D value and the correction amount in the crowning device. A press brake having a control device for controlling the mold installation body, the crowning device, the bending angle measuring device, and the bending angle measuring device moving positioning device so as to perform the main bending process on the workpiece with a die; is there.

  According to a second aspect of the present invention, in the press brake according to the first aspect, the calculated true D value and the correction amount in the crowning device correspond to the bending condition of the workpiece input in the input unit. A storage unit for storing the workpiece, and the control device corresponds to the true D value stored in the storage unit and the correction amount in the crowning device stored in the storage unit. A press brake that controls the mold installation body and the crowning device so that the workpiece is subjected to a final bending process using the corresponding true D value and the correction amount of the crowning device. It is.

  According to a third aspect of the present invention, in the press brake according to the second aspect, the true D value stored in the storage unit is a workpiece bending condition input in the input unit and a correction amount in the crowning device Even when the above-described true D value and the correction amount by the crowning device are used, a blocking signal that prevents the workpiece from being bent completely is input to the input. When the blocking signal is input from the input unit, the control device determines the true D value corresponding to the bending condition of the workpiece and the correction amount in the crowning device. Is calculated in the storage unit, the D value for provisional bending is calculated, the workpiece is provisionally bent, the provisional bending angle during pressurization is measured, and the provisional bending during unloading is performed. Measure the angle and scan the workpiece. Calculate the ringback amount, calculate the true D value and the correction amount in the crowning device, and perform the main bending of the workpiece, the mold installation body, the crowning device, and the bending angle. The press brake controls the measuring device and the bending angle measuring device moving positioning device.

  According to a fourth aspect of the present invention, there is provided a workpiece bending method for bending a plate-like workpiece using the first die, the second die, and a bending angle measuring device, and the true bending angle of the workpiece. A temporary bending D value calculating step for calculating a temporary bending D value for temporarily bending the workpiece using a bending condition of the workpiece, and a temporary bending D calculated in the temporary bending D value calculating step. In a state where a temporary bending process is performed on the workpiece with the first mold and the second mold using values, and the temporary bending process is performed in the temporary bending process And a temporary bending angle measurement step during pressurization for measuring the temporary bending angle during pressurization at the first predetermined portion, and the temporary bending angle during pressurization measured in the temporary bending angle measurement step during pressurization. In the state of unloading the applied pressure of the bending process, Unloading temporary bending angle measurement by moving the bending angle measuring device and measuring the unbending temporary bending angle at the second predetermined portion of the workpiece and moving the bending angle measuring device. Step, a temporary bending angle during pressurization at the first predetermined portion of the workpiece measured in the temporary bending angle measurement step during pressurization, and a first of the workpiece measured in the temporary bending angle measurement step during unloading The unloading provisional bending angle at a predetermined portion of 1 is used to calculate the springback amount of the workpiece, the true bending angle of the workpiece, and the springback amount calculation step. Using the calculated springback amount and the unloading provisional bending angle measured in the unloading provisional bending angle measurement step, the true D value and the crowning used to perform the main bending process on the workpiece True D value for calculating the correction amount Using the true D value calculated in the rounding correction amount calculating step, the true D value and the crowning correction amount calculating step, and the correction amount in the crowning, the first type and the second type It is a bending method of a work which has the 1st main bending process process which carries out a main bending process to a work.

  The invention according to claim 5 is the workpiece bending method according to claim 4, wherein the true D value calculated in the true D value / crowning correction amount calculating step and the correction amount in crowning are A storage step of storing in the storage unit corresponding to the bending condition of the workpiece including the true bending angle of the workpiece, and a true D value in which the bending condition of the workpiece including the true bending angle is stored in the storage unit A determination step of determining whether or not the correction amount corresponds to the amount of correction in the crowning device; and a true D value in which the bending condition of the workpiece including the true bending angle in the determination step is stored in the storage unit; When it is determined that it corresponds to the correction amount in the crowning device, the second bending process is performed on the workpiece using the corresponding true D value and the correction amount in the crowning. Work having a main bending process A bending method is.

  A sixth aspect of the present invention is the workpiece bending method according to the fifth aspect, wherein the workpiece D bending condition including the true bending angle in the determination step is stored in the storage unit. And the correction amount in the crowning device, it is determined that the workpiece is bent using the corresponding true D value and the correction amount in the crowning, or The provisional bending D value is calculated assuming that the true D value corresponding to the bending condition of the workpiece including the true bending angle and the correction amount in the crowning device do not exist in the storage unit. , Temporarily bending the workpiece, measuring the temporary bending angle during pressurization, measuring the temporary bending angle during unloading, calculating the springback amount of the workpiece, and calculating the true D value And the correction amount in the crowning device Either this bending of the workpiece, a bending method of a workpiece having a selection step of selecting a.

  According to the present invention, with a simple configuration using one bending angle measuring device (a pair of angle sensors), the workpiece (especially a long workpiece) is corrected to the workpiece while correcting the springback amount and the crowning amount. The effect that it can perform a bending process is produced.

It is a front view which shows schematic structure of a press brake. It is a side view which shows schematic structure of a press brake, and is the II arrow directional view in FIG. It is a figure which shows the bending process of the workpiece | work using a punch and die | dye. It is a three-view figure which shows the workpiece | work to which the bending process was given. It is a block diagram which shows the control apparatus (control part) etc. of a press brake. It is a flowchart which shows operation | movement of a press brake. It is a flowchart which shows operation | movement of a press brake. It is a figure which shows the bending process of a workpiece | work, and is the figure which looked at the workpiece | work bent with a prespray from the Y-axis direction, and was the figure seen from the same direction as FIG.4 (c). (A), (b), (c) is a figure which shows the temporary bending process of a workpiece | work, (b) has shown the state at the time of pressurization, (c) has shown the state at the time of unloading Yes. It is a figure which shows the bending process of the conventional workpiece | work.

  A press brake (work bending machine) 1 according to an embodiment of the present invention uses a first die (for example, a die such as a die D) and a second die (for example, a die such as a punch P). The plate-like workpiece W (a plate-like workpiece or a plate-like portion of the workpiece) is bent.

  Hereinafter, for convenience of explanation, one horizontal direction is defined as an X-axis direction, another horizontal direction perpendicular to the X-axis direction is defined as a Y-axis direction, and orthogonal to the X-axis direction and the Y-axis direction. The direction (vertical direction) to be used is the Z-axis direction. The X-axis direction is the left-right direction of the press brake 1, and the Y-axis direction is the front-rear direction of the press brake 1.

  As shown in FIGS. 1 and 2, the press brake 1 includes a first mold installation body (for example, a lower table) 5 supported by the frame 3, a second mold installation body (for example, an upper table) 7, , A crowning device 9, a bending angle measuring device (angle sensor) 11, a bending angle measuring device moving / positioning device 13, and a control device 15.

  A flat rear support plate 17 is integrally provided on the lower front side of the frame 3. A front support plate 19 having substantially the same shape as the rear support plate 17 is provided on the front side of the rear support plate 17. The thickness direction of the rear support plate 17 and the front support plate 19 is the Y-axis direction. When viewed from the Y-axis direction, the rear support plate 17 and the front support plate 19 are substantially overlapped with each other, and are developed in the YZ center plane (including the center of the press brake 1 in the Y-axis direction and the Z-axis direction). The planar upper end surface of the rear support plate 17 and the planar upper end surface of the front support plate 19 extend in a straight line in the X-axis direction.

  The front support plate 19 is supported by the rear support plate 17 via a spacer 21. As a result, a predetermined gap (gap whose dimension in the Y-axis direction is equal to the thickness of the spacer 21) 23 is formed between the rear support plate 17 and the front support plate 19.

  Further, a through hole 25 for installing the crowning device 9 is formed in the rear support plate 17 and the front support plate 19. The through-hole 25 is formed in, for example, a rectangular shape, and is formed as a single or a plurality (three in FIG. 1). The through hole 25 includes a lower surface 27 that extends in the horizontal direction and an upper surface 29 that is parallel to the lower surface 27. When viewed from the Y-axis direction, the through hole 25 and the front support plate 19 of the rear support plate 17. The through holes 25 overlap each other.

  Further, when a plurality of through holes 25 are provided, the positions of the through holes 25 coincide with each other in the Z-axis direction, with a predetermined interval in the X-axis direction, and on the YZ center plane of the press brake 1. They are arranged symmetrically.

  The lower table 5 is formed in a rectangular flat plate shape, for example. The thickness dimension of the lower table 5 is slightly smaller than the dimension of the gap 23. The lower table 5 is sandwiched between the rear support plate 17 and the front support plate 19 so that the thickness direction is in the Y-axis direction, and is positioned between the rear support plate 17 and the front support plate 19. ing. However, since the thickness dimension of the lower table 5 is slightly smaller than the dimension of the gap (interval) 23, the lower table 5 is in the state of being sandwiched between the rear support plate 17 and the front support plate 19. The table 5 is movable in the Y-axis direction and the Z-axis direction with respect to the rear support plate 17 and the front support plate 19.

  When viewed from the Y-axis direction, the dimension of the lower table 5 in the X-axis direction is slightly smaller than the dimensions of the rear support plate 17 and the front support plate 19 in the X-axis direction. The both ends of the lower table 5 in the X-axis direction are positioned outside the through hole 25. When viewed from the Y-axis direction, the planar upper end surface and the planar lower end surface of the lower table 5 extend linearly in the X-axis direction. Further, when viewed from the Y-axis direction, the planar upper end surface of the lower table 5 is located above the upper end surfaces of the rear support plate 17 and the front support plate 19, and The end face is located in the middle of the through hole 25 in the Z-axis direction. Thereby, when viewed from the Y-axis direction, a part of the lower table 5 is exposed at the through hole 25.

  Further, the lower table 5 has both ends in the X-axis direction via the pair of columnar shaft members (shaft members arranged symmetrically with respect to the YZ center plane) 31 and the front support plate 17 and the front side. The support plate 19 is supported. Thereby, the lower table 5 is a both-end support beam having both ends supported by the rotation support shaft. Note that the pair of shaft members 31 are located outside the through hole 25 in the X-axis direction.

  The upper table 7 is supported on the frame 3 by a linear guide bearing (not shown) on the upper front side of the frame 3. The upper table 7 is moved and positioned in the Z-axis direction (direction approaching or moving away from the lower table 5) by an actuator (such as a hydraulic cylinder) such as a servo motor 33 via a ball screw (not shown). It has become so.

  The upper table 7 is also formed in a flat plate shape, and is disposed above the lower table 5 away from the lower table 5 so that the thickness direction is the Y-axis direction. When viewed from the Y-axis direction, the upper table 7 is arranged symmetrically with respect to the YZ center plane, and the lower surface of the flat plate-like upper table 7 faces the lower surface of the lower table 5 in parallel and faces the X-axis direction It extends in a straight line.

  The lower surface of the upper table 7 has the same length as the upper surface of the lower table 5 and is located at the same position as the lower table 5 in the X-axis direction. Furthermore, also in the Y-axis direction, the lower surface of the upper table 7 is located at the same position as the X-axis direction and the upper surface of the lower table 5.

  The servo motors 33 are provided on the left and right sides of the upper table 7 (arranged symmetrically with respect to the YZ center plane). The left servo motor 33A and the right servo motor 33B are driven substantially synchronously. When the pair of servo motors 33 (33A, 33B) is driven, the upper table 7 moves relative to the lower table 5 while the lower surface of the upper table 7 is kept substantially parallel to the upper surface of the lower table 5. It has become. Further, by stopping the driving of the servo motor 33 and preventing the rotation output shaft of the servo motor 33 from rotating (for example, by applying a servo brake to the rotation output shaft), the upper table 7 is positioned and this position is changed. To be maintained.

  Note that the lower table 5 may be moved and positioned in the Z-axis direction instead of or in addition to the upper table 7 being moved and positioned. In any case, any configuration is acceptable as long as the upper table 7 can be relatively moved and positioned in the direction in which the upper table 7 approaches and separates from the lower table 5.

  For example, a first die (for example, a die D) is detachably and integrally installed on the lower table 5 via a die holder DH. A second die (for example, punch P) is detachably and integrally installed on the upper table 7 via, for example, a punch holder PH.

  In the Y-axis direction, the center of the punch (installed punch) P installed on the upper table 7 and the center of the die (installed die) D installed on the lower table 5 coincide with each other. . In FIG. 1, the dimensions in the X-axis direction of the punch P, the punch holder PH, the die D, and the die holder DH are the same as the dimensions in the X-axis direction of the lower table 5 and the upper table 7. , The dimension in the X-axis direction of the punch P, punch holder PH, die D, and die holder DH is smaller than the dimension in the X-axis direction of the lower table 5 and the upper table 7, and the punch P, punch holder PH, die D and the die holder DH are arranged in the X-axis direction at a position biased to the center of the lower table 5 or the upper table 7 or to the left or right.

  In the state where the upper table 7 is raised, the installed punch P is separated from the installed die D above the installed die D as shown in FIG. 2 and FIG. When the upper table 7 is lowered, the workpiece W is sandwiched between the “V” -shaped concave portion of the die D and the “V” -shaped convex portion of the punch P as shown in FIG. W is bent. The workpiece W that has been bent is shaped, for example, as shown in FIG.

  The crowning device 9 is a device that performs crowning on the lower table 5, and includes, for example, a hydraulic cylinder 35. The hydraulic cylinder 35 is installed in each of the through holes 25 of the support plates 17 and 19. The lower end of the casing of the hydraulic cylinder 35 is in contact with the lower surface of the through hole 25 and is provided integrally with the support plates 17 and 19. The tip (upper end) of the rod of the hydraulic cylinder 35 is in contact with the lower surface of the upper table 7.

  The lower table 5 is crowned by supplying compressed oil (hydraulic hydraulic oil whose pressure is higher than atmospheric pressure) to the hydraulic cylinder 35. By the crowning of the lower table 5, the lower table 5 (punch P) becomes a slightly convex curve upward as shown by a broken line L1 in FIG.

  The pressure of the hydraulic oil (compressed oil) supplied to each hydraulic cylinder 35 is equal to each other, but the pressure of the compressed oil supplied to each hydraulic cylinder 35 may be changed for each hydraulic cylinder 35. Thereby, the form of the curve L1 can be changed more variously.

  Further, the crowning device 9 may perform crowning on the upper table 7 instead of or in addition to performing crowning on the lower table 5.

  The bending angle measuring device 11 is a device that measures the bending angle of the workpiece W. As the bending angle measuring device 11, for example, a device described in JP-A-2006-205256 is adopted. One (a pair) of bending angle measuring devices 11 (11A, 11B) are provided, for example. Then, one bending angle measuring device 11A measures the inclination of one side of the workpiece W relative to the horizontal plane (the front side in the press brake 1), and the other bending angle measuring device 11B measures the other side of the workpiece W relative to the horizontal plane ( By measuring the inclination of the rear side of the press brake 1, the bending angle of the workpiece W can be measured.

  The bending angle measuring device movement positioning device 13 moves and positions the bending angle measuring device 11 in the extending direction (X-axis direction) of the bending line of the workpiece W. The extending direction of the bending line of the workpiece W is the longitudinal direction of the lower table 5 and the upper table 7, the longitudinal direction of the installed die D installed on the lower table 5, and the installed punch P installed on the upper table 7. Is coincident with the longitudinal direction.

  Moreover, the bending angle measuring device movement positioning device 13 moves and positions the bending angle measuring device 11 by, for example, a linear motor. The bending angle measuring device 11 by the bending angle measuring device moving positioning device 13 can be moved and positioned over almost the entire length of the lower table 5 and the upper table 7.

  The bending angle measuring device 11 and the bending angle measuring device moving positioning device 13 are provided obliquely below the installed die D. Further, as described above, the bending angle measuring device 11 and the bending angle measuring device moving positioning device 13 are provided as a pair on the front side and the rear side of the installed die D.

  The front bending angle measuring device 11A and the rear bending angle measuring device 11B are synchronously moved and positioned by a bending angle measuring device moving positioning device 13 supporting the bending angle measuring device 11B. That is, the front bending angle measuring device 11A and the rear bending angle measuring device 11B always coincide with each other in the X-axis direction.

  In the above description, the workpiece W is bent by the ZX center plane of the installed die D and the installed punch P (in the X axis direction and the Z axis direction through the center of the installed die D and installed punch P). As long as it is made symmetrical with respect to the unfolded plane, the configuration may be such that one bending angle measuring device 11 or the like (for example, the rear bending angle measuring device 11B or the like) is deleted.

  The press brake 1 is provided with an input unit 37 and a display unit 39 (see FIG. 5). The display unit 39 is configured by an LCD, for example, and the input unit 37 is configured by a touch panel provided on the display unit 39, for example.

  From the input unit 37, the bending condition of the workpiece including the true bending angle of the workpiece W (target bending angle of the workpiece W; the final bending angle of the workpiece W as a product or a semi-finished product) is input. .

  As a bending condition of the workpiece W, in addition to the true bending angle of the workpiece W, the material of the workpiece W and the thickness of the workpiece W can be listed. Furthermore, as a workpiece bending condition, a shape or form other than the thickness of the work W (at least one of the other forms shown below) may be adopted. As other forms, for example, the length of the bending line in the workpiece W, the width of the workpiece W (the dimension of the workpiece W in the direction orthogonal to the extending direction and the thickness direction of the bending line of the workpiece W), The position of the bending line, the mold information of the punch P and the die D used for bending the workpiece W (the shape of the mold, the installation position of the mold in the press brake 1), and the like can be listed.

  As illustrated in FIG. 5, the control device 15 includes a control unit (CPU) 41 and a memory 43. The memory 43 is provided with a work information storage unit 45, a mold information storage unit 47, an operation program storage unit 49, and a bending condition storage unit 51.

  The workpiece information storage unit 45 is a part that stores (stores) the ID of the workpiece W in association with the form of the workpiece W. For example, when only the ID of the workpiece W is input from the input unit 37, Information such as the true bending angle, material and thickness of the workpiece W corresponding to the input ID is output to the control unit 41.

  The mold information storage unit 47 is a part that stores the mold ID and the mold form in association with each other. For example, when only the mold ID is input from the input unit 37, this input is performed. Information such as the shape of the mold corresponding to the ID is output to the control unit 41.

  The operation program storage unit 49 is a part that stores the operation procedure of the press brake 1 and the like. Details of the bending condition storage unit 51 will be described later. A servo motor (D-axis servo motor) 33 that drives the upper table 7 is driven by a D-axis drive unit 53, and the crowning device 9 is driven by a CC drive unit 55. .

  The press brake 1 is controlled by the control unit 41 (control device 15) according to the operation program stored in the operation program storage unit 49, and the servo motor 33, the crowning device 9, the bending angle measurement device 11 and the upper table 7 are controlled. The bending angle measuring device moving / positioning device 13 is appropriately controlled.

  More specifically, first, using the bending condition (bending condition including the true bending angle) of the workpiece W input from the input unit 37, a temporary bending D value (for the workpiece W) for temporarily bending the workpiece W. The distance between the die D and the punch P when pre-bending is calculated (obtained).

  The temporary bending angle of the workpiece W by the temporary bending process is a slightly larger bending angle than the true bending angle. For example, when the true bending angle of the workpiece W is 90 °, the temporary bending angle is about 91 °. The temporary bending D value may be directly input by the input unit 37 instead of being calculated. In this case, a temporary bending angle of the workpiece W may be adopted that is slightly larger than the true bending angle.

  Subsequently, using the provisional bending D value calculated as described above, without being corrected by the crowning device 9, the installed die D installed in the lower table 5 and the installation installed in the upper table 7 are used. The workpiece W is temporarily bent by the finished punch P.

  Then, in the state where the above-described provisional bending process is performed (in a state where the workpiece W is pressurized with the distance between the installed die D and the installed punch P set to the provisional bending D value), The temporary bending angle at the time of pressurization at the first predetermined portion (for example, the central portion in the longitudinal direction of the workpiece W) is measured by moving and positioning the bending angle measuring device 11 with the bending angle moving positioning device 13. ing.

  Subsequently, after the measurement of the temporary bending angle at the time of pressurization described above, the applied pressure of the temporary bending process is unloaded (details will be described later), and the unloaded state (the state where the unloading is finished) is performed. Temporary bending angle during unloading at one predetermined portion (for example, the central portion of the workpiece W in the longitudinal direction) and a second predetermined portion of the workpiece W (for example, one end and the other end in the longitudinal direction of the workpiece W) The provisional bending angle at the time of unloading at (part) is measured by moving and positioning the bending angle measuring device 11 with the bending angle measuring device moving positioning device 13.

  Subsequently, the temporary bending angle during pressurization (for example, the temporary bending angle during pressurization at the center in the longitudinal direction of the workpiece W) at the first predetermined portion of the measured workpiece W and the first measured portion of the workpiece W. A spring back amount (spring back angle) in bending of the workpiece W using the unbending temporary bending angle (for example, the unloading temporary bending angle at the center in the longitudinal direction of the workpiece W) at a predetermined portion of 1 Is calculated.

  Subsequently, the true bending angle input from the input unit 37, the calculated spring back amount, the measured unloading temporary bending angle (for example, the unloading temporary bending angle at the center in the longitudinal direction of the workpiece W). And the workpiece W using the temporary bending angle at unloading at one end in the longitudinal direction of the workpiece W and the temporary bending angle at unloading at the other end in the longitudinal direction of the workpiece W). The true D value (distance between the die D and the punch P when the main workpiece is bent) and the correction amount (CC correction amount) in the crowning device 9 ) And are calculated.

  Subsequently, using the calculated true D value and the correction amount in the crowning device 9, the workpiece W (a workpiece that has been temporarily bent may be temporarily bent or temporarily bent) may be set by the installed die D and the installed punch P. The actual bending process (true bending process) is performed not on the workpiece itself but on a workpiece that has not been provisionally bent with the same specifications as the workpiece that has been temporarily bent.

  In the above-described operation, the temporary bending process and the main bending process for the workpiece W are started when the start button of the input unit 37 is pressed.

  Here, unloading when measuring the amount of springback of the workpiece W (unloading of the applied pressure in the temporary bending after the measurement of the temporary bending angle during pressurization) will be described in detail.

  In the state shown in FIG. 9A, a flat work (material) W is placed and placed on the die D. When the punch P is lowered to the temporary bending D value from the state shown in FIG. 9A, the state shown in FIG. 9B is obtained. In this state, the temporary bending angle during pressurization is measured. In the state shown in FIG. 9B, the force (pushing force) by which the punch P and the die D press the work W is, for example, about 1000 kgf (9800 N) at the maximum.

  In the state shown in FIG. 9B, the temporary bending angle of the workpiece W is continuously measured by the bending angle measuring device 11. When the punch P is lifted by a slight amount from the state shown in FIG. 9B (for example, 0.05 mm), the bending angle of the workpiece W measured by the bending angle measuring device 11 is changed by the spring back of the workpiece W. Slightly increases.

  Thereafter, when the above-described slight increase in the punch P and the measurement of the bending angle of the workpiece W are repeated a certain number of times, the slight increase in the bending angle of the workpiece W is almost as shown in FIG. (Slight increase is smaller than a predetermined threshold). Thereby, unloading when the workpiece W is temporarily bent is completed. When the unloading is completed, the punch P is stopped from rising, and the temporary bending angle of the workpiece W is measured by the bending angle measuring device 11.

  In the state shown in FIG. 9 (c), the force (pushing force) by which the punch P and the die D pressurize the workpiece W is preferably 0 kgf, but actually 10 kgf to 50 kgf (98 N to 490N). The difference between the bending angle of the workpiece W shown in FIG. 9C and the bending angle of the workpiece W shown in FIG. 9B is the spring back amount (spring back angle) of the workpiece W.

  Further, the press brake 1 is provided with a storage unit (bending condition storage unit) 51 as described above. The bending condition storage unit 51 associates the calculated true D value and the correction amount in the crowning device 9 with the bending condition (bending condition including the true bending angle) of the workpiece W input by the input unit 37. To remember. The bending condition storage unit 51 stores, for example, a plurality of types of bending conditions, true D values corresponding to these bending conditions, and correction amounts in the crowning device 9 in a database.

  The control device 15 (control unit 41) appropriately controls the servo motor 33 and the crowning device 9 of the upper table 7.

  That is, the bending condition (bending condition including the true bending angle) of the workpiece W input by the input unit 37 corresponds to the true D value stored in the bending condition storage unit 51 and the correction amount in the crowning device 9. In this case, the temporary bending angle at unloading is not calculated without calculating the above-described temporary bending D value, without performing temporary bending processing on the workpiece W, and without measuring the temporary bending angle during pressurization. Without measuring, calculating the springback amount, and calculating the true D value and the correction amount in the crowning device, the corresponding true D value and the correction amount in the crowning device Then, the workpiece W is suddenly subjected to the main bending process.

  Further, in the press brake 1, the following operation is performed when a blocking signal that prevents the stored contents of the bending condition storage unit 51 from being used is input via the input unit 37.

  Here, the blocking signal refers to the true D value stored in the bending condition storage unit 51 and the crowning device 9 in which the bending condition (bending condition including the true bending angle) of the workpiece W input at the input unit 37 is stored. Even if it corresponds to the amount of correction, the bending of the workpiece W is prevented from being performed using the corresponding true D value and the amount of correction by the crowning device 9 (performed). Signal). In addition, although the blocking signal once input is effective as long as the blocking state cancel signal is not input from the input unit 37, the blocking signal may be effective only once or a plurality of times. Good. That is, after inputting the blocking signal, the blocking signal may be effective only when bending one or a predetermined plurality of workpieces W.

  Return to the operation when the blocking signal is input. When the blocking signal is input from the input unit 37, the control unit 41 appropriately controls the servo motor 33, the crowning device 9, the bending angle measuring device 11, and the bending angle measuring device moving positioning device 13 of the upper table 7. It has become.

  More specifically, assuming that the true D value corresponding to the bending condition of the workpiece W and the correction amount in the crowning device 9 do not exist in the bending condition storage unit 51, the above-described calculation of the temporary bending D value is performed. The above-mentioned temporary bending process of the workpiece W is performed, the above-described temporary bending angle at the time of pressurization is measured, the above-described temporary bending angle at the time of unloading is measured, and the springback amount of the above-described workpiece W is calculated. The true D value and the correction amount in the crowning device 9 are calculated, and the workpiece W is bent as described above.

  In this way, the true D value separately calculated after the inhibition signal is input and the correction amount in the crowning device 9 may be overwritten in the bending condition storage unit 51 or separately stored in another area of the bending condition storage unit 51. May be. When storing separately, it is desirable to input the lot number and manufacturing apparatus of the workpiece W (material) from the input unit 37 and store them in accordance with the bending conditions of the workpiece W. In this case, the workpiece bending conditions described above include the lot number of the workpiece W (material) and the manufacturing apparatus.

  Next, the operation of the press brake 1 will be described with reference to the flowcharts of FIGS. 6 and 7 and FIG. For example, by the operation of the press brake 1, a plate-shaped workpiece (for example, a flat plate shape of the workpiece) is used by using the first mold (for example, die D), the second mold (for example, punch P), and the bending angle measuring device 11. The part bending method for bending the workpiece W is performed.

  As an initial state, the upper table 7 is raised, the crowning device 9 is not operating (the upper surface of the lower table 5 is a horizontal surface), and the bending angle measuring device 11 is a predetermined default in the X-axis direction. It is assumed that it is located at a position.

  In the initial state, when a workpiece bending condition including a true workpiece bending angle (for example, 90.0 °) is input from the input unit 37 (S1), the workpiece bending including the input true bending angle is performed. It is determined whether or not the condition corresponds to the true D value stored in the bending condition storage unit 51 and the correction amount in the crowning device (S3; determination step).

  When it is determined in the determination step of step S3 that the bending condition of the workpiece including the true bending angle does not correspond to the true D value stored in the bending condition storage unit 51 and the correction amount in the crowning device. Is a provisional bending D value for provisionally bending the workpiece W using the workpiece bending condition including the true bending angle of the workpiece (temporary bending in a state where the workpiece W is not restored by springback). An angle, for example, a D value corresponding to a temporary bending angle of 89.5 ° is calculated (S5: D value calculation stage for temporary bending).

  Subsequently, when a workpiece W is installed on the press brake 1 by a robot or an operator (not shown) and a temporary bending start signal is input via the input unit 37 (S7), the temporary bending D value calculated in step S5 is obtained. Using the installed die D and the installed punch P (lowering the installed punch P to a position corresponding to the provisional bending D value) without correction by the crowning device 9, the workpiece W is temporarily bent. (S9; provisional bending process).

  Subsequently, in a state where the temporary bending process is performed in step S9 (in a state where the workpiece W is pressurized with the distance between the installed die D and the installed punch P set as a temporary bending D value). Pressing temporary bending angle at a first predetermined portion of the workpiece W (for example, the central portion in the longitudinal direction of the workpiece W) (for example, pressing temporary bending angle measured at one central portion in the longitudinal direction of the workpiece W) ) Is measured by moving the bending angle measuring device 11 to the measurement position of the temporary bending angle during pressurization (at the center of the longitudinal direction of the workpiece W) (S11; temporary bending angle measurement step during pressurization) ).

  Fig.8 (a) has shown the workpiece | work W in step S11. In step S11, the temporary bending angle at the time of pressurization of the central part WA1 in the workpiece W is measured. Here, it is assumed that the temporary bending angle during pressurization at the central portion WA1 is, for example, 89.5 °.

  Subsequently, after the measurement of the temporary bending angle during pressurization in step S11, the first bending of the workpiece W is performed in a state where the applied pressure of the temporary bending process is unloaded and this unloading is performed (a state where the unloading is finished). Temporary bending angle at unloading at a predetermined portion (for example, temporary bending angle at unloading measured at one central portion in the longitudinal direction of the workpiece W) and unloading at a second predetermined portion of the workpiece W The temporary bending angle (for example, the temporary bending angle at the time of unloading measured at a plurality of locations in the longitudinal direction of the workpiece W at a plurality of locations) and the bending angle measuring device 11 at the measurement position of the temporary bending angle at the time of unloading ( The workpiece W is moved to the central portion in the longitudinal direction and the left and right end portions), positioned, and measured (S13; temporary bending angle measurement process at unloading).

  FIG. 8B shows the workpiece W in step S13. In step S13, the temporary bending angle at the time of unloading at the central part WB1, the left end part WB2, and the right end part WB3 in the workpiece W is measured. Here, the temporary bending angle at the time of unloading of the central portion WA1 is, for example, 91.0 °, and the temporary bending angle at the time of unloading of the left end portion WB2 is, for example, 90.5 °, and the removal of the right end portion WB3 is performed. The temporary bending angle during loading is assumed to be 90.5 °, for example.

  Subsequently, the temporary bending angle during pressurization (for example, 89.5 °) at the first predetermined portion (for example, the central portion in the longitudinal direction) of the workpiece W measured in step S11, and the workpiece W measured in step S13. The springback amount (springback angle) of the workpiece W is calculated using the temporary bending angle (for example, 91.0 °) at the time of unloading at the first predetermined portion (for example, the central portion in the longitudinal direction) (91. 0 ° -89.5 ° = 1.5 °) (S15; springback amount calculation stage).

  Subsequently, the true bending angle (for example, 90.0 °) of the workpiece W input in step S1, the springback amount (for example, 1.5 °) calculated in step S15, and the unloading provisional time measured in step S13. Using the bending angle (for example, the measurement angle 91.0 ° at the center of the workpiece W and the measurement angle 90.5 ° at both ends of the workpiece W), the workpiece W is subjected to a final bending process (product or semi-finished product). The true D value and the correction amount (for example, 0.5 °) used by the crowning device 9 are calculated (S17; true D value / crowning correction amount calculating step). ).

  Subsequently, using the true D value calculated in step S17 and the correction amount in the crowning device 9, the workpiece W (preliminarily bent workpiece W may be used) with the installed die D and the installed punch P. The main bending is performed on the workpiece W itself, which is not the bent workpiece W itself, but may be a workpiece that is not temporarily bent with the same specifications as the temporarily bent workpiece (S19; first main bending step; based on the temporary bending). This bending process).

  By the way, FIG.8 (c) has shown the workpiece | work W at the time of pressurization of this bending process using true D value and the correction amount in the crowning apparatus 9 in step S17. In FIG. 8C, the bending angle of the workpiece W is not measured, but if it is measured, the angle of the workpiece W is 88 at the central portion WC1, the left end portion WC2, and the left end portion WC3 of the workpiece W. It should be 5 °.

  Subsequently, in order to confirm whether or not the workpiece W is bent at a target bending angle, the installed punch P is slightly raised to remove the pressure on the workpiece W (unloading), The final bending angle of W (the actual bending angle at the time of unloading) is measured in the same manner as in step S13 (S21; final bending angle measurement stage). In step S21, the bending angle of the workpiece W is slightly increased by the spring back. FIG. 8D shows the workpiece W when the installed punch P is raised and separated from the workpiece W. In FIG. 8D, the bending angle of the workpiece W should be the target angle of 90.0 ° at the central portion WD1, the left end portion WD2, and the left end portion WD3 of the workpiece W.

  Subsequently, it is determined whether or not the error of the main bending angle of the workpiece W measured in step S21 is within the allowable value range (S23; main bending angle determination step).

  If it is determined in step S23 that the error in the main bending angle of the workpiece W is within the allowable value range, the true D value calculated in step S17 and the correction amount in crowning are determined as the true value of the workpiece. The bending condition is stored in the bending condition storage unit 51 corresponding to the bending condition of the workpiece including the bending angle (S25; storage stage).

  Subsequently, the installed punch P is further raised and separated from the workpiece W, and the workpiece W is taken out from the press brake 1 by a robot or operator (not shown) (step S27), the correction amount of the crowning device 9 is set to “0”, and bending is performed. The angle measuring device 11 is positioned at a predetermined default position in the X-axis direction and returns to the initial state.

  In step S3, it is determined (determination) that the bending condition of the workpiece W including the true bending angle corresponds to the true D value stored in the bending condition storage unit 51 and the correction amount in the crowning device. In this case, without calculating the provisional bending D value, without subjecting the workpiece W to provisional bending, without measuring the provisional bending angle during pressurization, and without measuring the provisional bending angle during unloading Without calculating the springback amount, and without calculating the true D value and the correction amount in the crowning device, using the corresponding true D value and the correction amount in the crowning, The workpiece is suddenly bent (S29; second final bending step; main bending step based on stored information).

  Further, in the determination in step S23, if the error in the main bending angle of the workpiece W is outside the allowable value range, the true D value calculated in step S17 and the correction amount in crowning are calculated. Correction is performed (S31). This correction is made by an operator via the input unit 37, for example.

  Then, the main bending process is performed in step S23 using the corrected true D value and the correction amount in the crowning.

  Incidentally, although not shown in the flowcharts of FIGS. 6 and 7, the true D value stored in the bending condition storage unit 51 is the bending condition of the workpiece W including the true bending angle at the determination stage of step S <b> 3. If it is determined that the workpiece W corresponds to the correction amount in the crowning device, the workpiece W is suddenly subjected to the main bending process using the corresponding true D value and the correction amount in the crowning (memory). The actual bending process based on the information is executed), or the true D value corresponding to the bending condition of the workpiece including the true bending angle and the correction amount in the crowning device do not exist in the bending condition storage unit 51. It is assumed that the operation of step S5 to step S19 is executed (the main bending process based on the temporary bending is executed) (the D value for temporary bending is calculated, the workpiece is temporarily bent, and the pressure is applied) Temporary bending angle measurement Measure the temporary bending angle during unloading, calculate the spring back amount of the workpiece, calculate the true D value and the correction amount in the crowning device, and perform the main bending of the workpiece. May be selected (a selection step may be provided).

  According to the press brake 1, the D value for temporary bending of the workpiece W is calculated, and the workpiece W is temporarily bent with the die D and the punch P using the calculated temporary bending D value. In a state where the temporary bending angle at the time of pressurization at the center portion of the workpiece W is measured using the pair of bending angle measuring devices 11 in a state where the pressure is applied, The unwinding temporary bending angles at a plurality of locations at the center and both ends of the workpiece W are measured by moving the bending angle measuring device 11 and positioning the workpiece W using the measured temporary bending angles as appropriate. The true D value used to perform the main bending process on the workpiece W using the true bending angle of the workpiece W, the spring back amount, and the temporary bending angle at the time of unloading. The amount of correction in the crowning is calculated, and the calculated true D And the amount of correction in the crowning, the workpiece W is subjected to a main bending process with the die D and the punch P, so that the workpiece (particularly a long workpiece) can be formed with a simple configuration using the pair of angle measuring devices 11. The workpiece W can be accurately bent while correcting the spring back and crowning of the W. For example, even if the length of the workpiece W is about 1000 mm, a bending process with a bending angle error within ± 15 ′ can be performed.

  In addition, since the angle measuring device 11 is configured to have only one pair, interference between the angle measuring devices can be surely avoided without using an interlock mechanism, and the manufacturing cost of the device can be reduced. Can do.

  Further, according to the press brake 1, a plurality of types (various aspects) of bending conditions, true D values corresponding to these bending conditions, and correction amounts in crowning are stored in the bending condition storage unit 51 as a database. (Save), and since the workpiece W can be bent based on the stored information, an operation such as provisional bending becomes unnecessary when bending the workpiece W, Accurate bending of the workpiece W can be performed efficiently.

  Further, according to the press brake 1, since it is possible to select whether or not the workpiece W is to be bent using the database of the bending condition storage unit 51, the same bending as that of the workpiece W previously bent is performed. It is not always necessary to perform a bending process using a database even if the workpiece W satisfies the conditions, and the bending angle due to the difference in the lot of the workpiece W (for example, the difference in the processing apparatus that processed the workpiece W before the bending process, etc.). Generation of errors can be minimized.

  In the operations shown in FIGS. 6 and 7, the operations in step S21, step S23, and step S31 may be deleted.

  In step S1, the pressure temporary bending angle is measured only at the central portion WA1, but instead of or in addition to measuring the pressure temporary bending angle at the central portion WA1, the workpiece W is measured. The temporary bending angle during pressurization may be measured at the left end portion WA2 or the right end portion WA3 of the workpiece W. Then, the springback amount or the like may be calculated using at least one of these measured values.

  In the above example, in the angle measurement result in step S13 (FIG. 8B), the bending angle between the part WB2 and the part WB3 is 90.5 ° which is equal to each other, but the part WB2 and the part WB3 It is also assumed that the bending angles are different from each other and are different. In this case, with respect to the true D value in step S17, the D values of the left and right servomotors 33A and 33B are changed as appropriate, for example, and further supplied to each hydraulic cylinder 35 of the crowning device 9. What is necessary is just to change the pressure of hydraulic fluid suitably.

  In the above description, the temporary bending angle 89.5 ° obtained in step S5 and the temporary bending angle 89.5 ° measured in step S11 are equal to each other, but the values of these temporary bending angles are different. It is also assumed that In this case, the true D value and the correction amount in the crowning device 9 may be calculated in step S17 using the difference between these angles.

1 Press brake 5 1st mold installation body (lower table)
7 Second mold installation body (upper table)
DESCRIPTION OF SYMBOLS 9 Crowning apparatus 11 Bending angle measuring apparatus 13 Bending angle measuring apparatus Movement positioning apparatus 15 Control apparatus 37 Input part 51 Storage part (bending condition storage part)
D First mold (die)
P 2nd mold (punch)
W Work

Claims (6)

In a press brake that bends a plate-shaped workpiece using the first mold and the second mold,
A first mold installation body on which the first mold is installed;
A second mold installation body in which the second mold is installed and is movable and positionable relative to the first mold installation body in a direction approaching / separating from the first mold installation body;
A crowning device for performing crowning on the first mold installation body;
A bending angle measuring device for measuring the bending angle of the workpiece;
A bending angle measuring device moving positioning device for moving and positioning the bending angle measuring device;
An input unit for inputting a bending condition of the workpiece including a true bending angle of the workpiece;
Using the bending condition of the workpiece input at the input unit, a temporary bending D value for temporarily bending the workpiece is calculated, and the calculated temporary bending D value is used to install the workpiece on the first mold installation body. The workpiece is temporarily bent with the installed first mold and the second mold installed on the second mold installation body, and the workpiece is temporarily bent in the state of being temporarily bent. The temporary bending angle at the time of pressurization at the first predetermined part of the workpiece is measured by the bending angle measuring device. In the state in which the workpiece is unloaded, the bending angle at the time of unloading at the first predetermined portion of the workpiece and the bending angle at the time of unloading at the second predetermined portion of the workpiece are determined by the bending angle measuring device moving positioning device. The bending angle measuring device is moved and positioned and measured, and the measured first position of the workpiece is measured. A spring back amount of the workpiece is calculated by using the temporary bending angle at the time of pressurization at the portion and the measured temporary bending angle at the time of unloading at the first predetermined portion of the workpiece, and input by the input unit. The true D value used to perform the main bending process on the workpiece using the calculated true bending angle, the calculated springback amount, and the measured temporary bending angle during unloading, and the correction amount in the crowning device And using the calculated true D value and the correction amount in the crowning device, the workpiece is bent with the installed first die and the installed second die. A control device for controlling the mold installation body, the crowning device, the bending angle measuring device, and the bending angle measuring device moving positioning device;
A press brake characterized by comprising: The press brake according to claim 1,
A storage unit that stores the calculated true D value and the correction amount in the crowning device in correspondence with the bending condition of the workpiece input by the input unit;
When the bending condition of the workpiece input by the input unit corresponds to the true D value stored in the storage unit and the correction amount in the crowning device, the control device corresponds to this. A press brake characterized by controlling the mold installation body and the crowning device so as to bend the workpiece with a true D value and a correction amount of the crowning device. The press brake according to claim 2,
Even if the bending condition of the workpiece input by the input unit corresponds to the true D value stored in the storage unit and the correction amount in the crowning device, this corresponding true A blocking signal for blocking the main bending of the workpiece using the D value and the correction amount in the crowning device is configured to be input from the input unit.
When the blocking signal is input from the input unit, the control device assumes that the true D value corresponding to the bending condition of the workpiece and the correction amount in the crowning device do not exist in the storage unit. Calculating the D value for temporary bending, pre-bending the workpiece, measuring the temporary bending angle during pressurization, measuring the temporary bending angle during unloading, and spring-backing the workpiece The mold installation body, the crowning device, and the bending angle measuring device are configured to calculate the amount, calculate the true D value and the correction amount in the crowning device, and perform the main bending of the workpiece. And a bending angle measuring device moving and positioning device. In a work bending method for bending a plate-like work by using a first die, a second die, and a bending angle measuring device,
A provisional bending D value calculation step of calculating a provisional bending D value for provisionally bending the workpiece using a workpiece bending condition including a true bending angle of the workpiece;
A temporary bending step of performing a temporary bending process on the workpiece with the first die and the second die using the temporary bending D value calculated in the temporary bending D value calculation step;
In a state where the temporary bending process in the temporary bending process is performed, a temporary bending angle measurement process during pressurization that measures a temporary bending angle during pressurization at the first predetermined portion of the workpiece;
After the measurement of the temporary bending angle during pressurization in the step of measuring the temporary bending angle during pressurization, the applied pressure of the temporary bending process is unloaded, and in this unloaded state, at the first predetermined portion of the workpiece An unloading temporary bending angle measuring step of measuring the unloading temporary bending angle and the unloading temporary bending angle at the second predetermined portion of the workpiece by moving the bending angle measuring device; ,
The temporary bending angle at the time of pressurization at the first predetermined portion of the work measured in the temporary bending angle measurement process at the time of pressurization and the first predetermined of the work measured at the temporary bending angle measurement process at the time of unloading. A spring back amount calculating step of calculating a spring back amount of the workpiece using a temporary bending angle at the time of unloading at the site;
Using the true bending angle of the workpiece, the springback amount calculated in the springback amount calculating step, and the unloading temporary bending angle measured in the unloading temporary bending angle measurement step, A true D value / crowning correction amount calculation stage for calculating a true D value used for bending and a correction amount in crowning;
Using the true D value calculated in the true D value / crowning correction amount calculation step and the correction amount in crowning, the workpiece is subjected to a main bending process using the first die and the second die. A first main bending process;
A workpiece bending method characterized by comprising: The workpiece bending method according to claim 4,
A storage that stores the true D value calculated in the true D value / crowning correction amount calculation step and the correction amount in the crowning in a storage unit in association with the bending condition of the workpiece including the true bending angle of the workpiece. Stages,
A discriminating step for discriminating whether or not the bending condition of the workpiece including the true bending angle corresponds to the true D value stored in the storage unit and the correction amount in the crowning device;
If it is determined in the determination step that the bending condition of the workpiece including the true bending angle corresponds to the true D value stored in the storage unit and the correction amount in the crowning device, this response Using the true D value and the amount of correction in the crowning, a second final bending process for performing a final bending process on the workpiece;
A workpiece bending method characterized by comprising: In the bending method of the workpiece | work of Claim 5,
If it is determined in the determination step that the bending condition of the workpiece including the true bending angle corresponds to the true D value stored in the storage unit and the correction amount in the crowning device, The actual D value and the amount of correction in the crowning are used to perform the main bending process on the workpiece, or the true D value and the crowning corresponding to the bending condition of the workpiece including the true bending angle. Assuming that the correction amount in the apparatus does not exist in the storage unit, calculating the D value for temporary bending, pre-bending the workpiece, and measuring the temporary bending angle during pressurization, Measure the temporary bending angle at the time of unloading, calculate the springback amount of the workpiece, calculate the true D value and the correction amount in the crowning device, and perform the main bending of the workpiece Or having a selection stage to select Bending method of a workpiece to be.

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