JP2005131650A - Method and device for detecting bending angle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a detecting method and a detecting device of a bending angle when performing the bending of a work with a press brake, the press brake and a die. <P>SOLUTION: This method is a method for detecting the bending angle A of the work W when performing the bending work of the work W with the press brake and the detecting method of the bending angle for detecting the bending angle A of the work on the basis of an inclined angle θ and a rotational angle α by detecting the inclined angle θ of the bisector LB by which the bending angle A of the work to the perpendicular line LA which is passed through the center in the width direction of the bending groove DV of the die D is bisected and also detecting the rotational angle α of the work to the horizon. The device is provided with an inclined angle detecting means 41 for detecting the inclined angle θ of the bisector LB of the bending angle A of the work to the perpendicular line LA which is passed through the center in the width direction of the bending groove DV of the die D and a rotational angle detecting means 11 for detecting the rotational angle α of the work to the horizon. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a bending angle detection method and apparatus, and a press brake and a die when a plate-shaped workpiece is bent by a press brake.

  Various bending angle detection devices have been developed to detect the bending angle of a workpiece when a plate-like workpiece is bent by a press brake. When a workpiece is bent by a press brake, the workpiece is bent into a V shape, and the inclination angle of the front portion and the inclination angle of the rear portion are detected from the bending line of the workpiece. The bending angle of the workpiece is detected based on both the front and rear inclination angles.

That is, when the workpiece is bent by the press brake, the inclination angle of the front portion of the workpiece with respect to the horizontal (the amount of jumping up with respect to the horizontal) and the inclination angle of the rear portion are not necessarily equal. It is necessary to detect the inclination angles of the part and the rear part. As a prior example related to the present invention, there is Patent Document 1.
JP 2001-121216 A

  As shown schematically in FIG. 8, the configuration of the bending angle detection device described in Patent Document 1 includes a support member 103 that can be moved up and down on a frame body 101 disposed between divided dies D. The front and rear rotators 105A and 105B rotatably provided on the upper portion of the support member 103 are rotated following the inclination of the front and rear parts of the workpiece, whereby the front and rear parts of the workpiece are inclined. The corners are individually detected. That is, when the rotating bodies 105A and 105B are rotated, the linear scales 109A and 109B are operated via the string-like members 107A and 107B to detect the rotation angle of the rotating bodies 105A and 105B. is there.

  According to the above configuration, the rotating bodies 105A and 105B follow the inclination of the front and rear portions of the workpiece and detect the inclination angles of the front and rear portions, so that the workpiece can be folded during the bending process. The bending angle can be detected accurately. As a configuration for detecting the inclination angle of the front part and the rear part of the workpiece, a distance sensor for optically detecting the distance is arranged on the front side and the rear side of the die D, and the workpiece is bent by this distance sensor. A configuration for detecting the angle has also been developed.

  As described above, in the configuration in which the sensors for detecting the bending angle of the workpiece are arranged before and after the die, the bending angle of the workpiece being bent can be accurately detected. However, conventionally, it is assumed that the initial state of the workpiece is in a horizontal state over the front and back of the die. For example, a rising portion is bent at one end side of the workpiece, and the L-shape is formed. When the workpiece is set on the die so that the rising portion is on the lower side, the rising portion becomes the falling portion.

  Therefore, if a workpiece that has been bent into an L-shape in advance is turned upside down and set on a die, the portion that becomes the falling portion may interfere with the sensor, making bending impossible. Even when bending is possible, the initial state varies depending on the presence of the falling portion, and an accurate bending angle may not be detected.

  The present invention has been made in view of the conventional problems as described above, and is a method for detecting a bending angle of a workpiece when the workpiece is bent by a press brake, and includes a die provided in the press brake. Detecting a tilt angle of a bisector that bisects a bending angle of the workpiece with respect to a vertical line passing through a center in a width direction of the bending groove, and detecting a rotation angle of the workpiece with respect to horizontal, and detecting the tilt angle. The bending angle of the workpiece is detected based on the rotation angle and the rotation angle.

  The present invention also relates to a bending angle detection device for detecting a bending angle of a workpiece that is bent by a press brake, and is a vertical passing through the center in the width direction of a bending groove in a die provided for the press brake. A tilt angle detecting means for detecting a tilt angle of a bisector of a bending angle of the work with respect to a line, and a rotation angle detecting means for detecting a rotation angle of the work with respect to the horizontal. It is a feature.

  In the bending angle detecting device according to the present invention, the inclination angle detecting means is a pair of distance detections arranged at symmetrical positions in the width direction with a center line passing through the center in the width direction of the bending groove in the die as a center. Means are provided.

  In the bending angle detection device according to the present invention, the tilt angle detection means is a pair of contacts disposed at symmetrical positions in the width direction with a center line passing through the center in the width direction of the bending groove in the die as a center. The upper ends of the pair of contacts are provided so as to be freely contactable with the lower surface of the workpiece during the bending process, and the lower ends of the pair of contacts are supported by a swinging member that is swingably provided. The swing angle detecting means for detecting the swing angle of the swing member is provided.

  In the bending angle detection device according to the present invention, the rotation angle detection means may include a rotation detector that can be raised and rotated following the upward rotation of the workpiece. It is a feature.

  The present invention also relates to a bending angle detecting device for detecting a bending angle of a workpiece that is bent by a press brake, and is a bracket that can be disposed between dies mounted on a lower table in the press brake. An inclination angle detecting means for detecting an inclination angle of a bisector of a bending angle of the workpiece with respect to a vertical line passing through a center in a width direction of a bending groove in a die provided for a press brake, and the horizontal direction The bracket is provided with a rotation angle detecting means for detecting the rotation angle of the workpiece.

  Further, the present invention is a die used for a press brake, for detecting an inclination angle of a bisector of a bending angle of a workpiece with respect to a vertical line passing through a center in a width direction of a bending groove provided in the die. Inclination angle detection means is provided.

  The present invention also includes an upper table provided with a punch for bending a workpiece, and a lower table provided with a die corresponding to the punch, so that one of the upper and lower tables can be moved up and down. In the press brake provided, an inclination angle detecting means for detecting an inclination angle of a bisector of a bending angle of the workpiece with respect to a vertical line passing through a center in a width direction of a bending groove in the die, and the horizontal direction A plurality of bending angle detecting devices provided with a rotation angle detecting means for detecting the rotation angle of the workpiece, provided at an upper part of the lower table as appropriate separated in the longitudinal direction of the die, and detecting each bending angle. The lower table is provided with vertical operation means for simultaneously moving the rotation angle detection means in the apparatus up and down.

  According to the present invention, the bending angle of the workpiece is detected by detecting the inclination angle of the bisector that bisects the bending angle of the workpiece and detecting the inclination angle (rotation angle) of the front side or the rear side of the workpiece. Therefore, the detection means for detecting the tilt angle (rotation angle) may be provided on either the front side or the rear side, and can solve the conventional problems as described above. is there.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. First, a press brake provided with a bending angle detection device will be schematically described.

  Referring to FIG. 1, a press brake 1 includes an upper table 3 on which a punch P for bending a plate-like workpiece (not shown in FIG. 1) is detachably mounted, and the punch P And a lower table 5 on which a corresponding die D is detachably mounted, and an actuator such as a hydraulic cylinder or a servo motor is used to move up or down one of the upper table 3 or the lower table 5 appropriately. 7 is provided. In the present embodiment, the actuator 7 is provided on the upper portion of the frame 9 in order to move the upper table 3 up and down.

  When the workpiece is bent by the cooperation of the punch P and the die D, the front side of the die D is detected in order to detect the upward inclination angle of the front portion from the bending line of the workpiece. A rotation angle detection device (rotation angle detection means) 11 for detecting an upward rotation angle (inclination angle) of the front portion of the workpiece is provided at appropriate intervals in the longitudinal direction of the die D. The rotation angle detection device 11 is mounted on an elevating beam 13 provided on the front side of the die D so as to be movable up and down.

  The elevating beam 13 is long in the longitudinal direction (left and right direction) of the die D, and constitutes an elevating means for moving the plurality of rotation angle detecting devices 11 up and down simultaneously. As a configuration for moving the lever up and down, various lifting mechanisms such as a wedge mechanism and a link mechanism can be employed. As a configuration for operating the elevating mechanism, for example, a configuration using an actuator such as an air cylinder as a drive source, or a manual mechanism such as a manual lever can be used. In short, any configuration may be used as long as the lifting beam 13 can be moved up and down.

  The rotation angle detection device 11 is for detecting an upward rotation angle (tilt angle) of the workpiece W with respect to the horizontal, and is configured as shown conceptually and schematically in FIG. In addition, although the case where the said rotation angle detection apparatus 11 is arrange | positioned at the front side (right side in FIG. 2) of the die D is illustrated, the said rotation angle detection apparatus 11 may be arrange | positioned at the back side of the die D. .

  As shown conceptually and schematically in FIG. 2, the rotation angle detection device 11 is mounted on the elevating beam 13 that is moved up and down by an elevating mechanism 15. The lifting mechanism 15 is exemplified by a structure in which the lifting beam 13 is supported by a lever 19 provided on a rotary shaft 17 that is long in the longitudinal direction of the die D.

  With the above configuration, when the lever 19 is rotated up and down by rotating the rotation shaft 17, the elevating beam 13 supported by the lever 19 moves up and down, and a plurality of rotations supported by the elevating beam 13 are performed. The angle detection device 11 is moved up and down at the same time. That is, the inclination angle of the front part of the workpiece is detected at a plurality of locations.

  The rotation angle detection device 11 includes a base member 21 supported by the elevating beam 13 and an elevating member 23 supported by the base member 21 so as to be movable up and down relatively. Between the elevating member 23, there is provided an elastic support means 25 such as a coil spring that elastically supports the elevating member 23 with respect to the base member 21.

  A fan-shaped rotation detector 27 that is always in surface contact with the lower surface of the front portion of the workpiece W from the die D and can follow the upward rotation of the front portion of the workpiece W is provided on the upper and lower members 23. It is rotatably supported via a pivot 29. In order to detect the rotation angle of the rotation detector 27 (the inclination angle of the front portion of the workpiece W), an appropriate string member 31 such as a chain is connected to the rotation detector 27.

  That is, one end portion of the string-like member 31 is connected to a position where the rotation detector 27 is pulled immediately when the rotation detector 27 rotates counterclockwise in FIG. A linear scale 33 is connected to the elevating member 23 so as to be movable up and down. The linear scale 33 is always pulled downward by an elastic member 35 such as a coil spring. In order to detect the movement of the linear scale 33, the elevating member 23 is provided with a detection head 37.

  The contact surface 27A where the rotation detector 27 contacts the workpiece W is normally in a horizontal state and is located at the same height as the upper surface of the die D or slightly lower than the upper surface of the die D. is there.

  In the above configuration, when the rotation detector 27 follows the bending of the workpiece W and rotates counterclockwise in FIG. 2, the string-like member 31 is pulled and the linear scale 33 is moved upward. Therefore, by detecting the upward movement amount of the linear scale 33, the rotation angle of the rotation detector 27 can be detected. As a result, the upward rotation angle, that is, the inclination angle of the front portion of the work W is detected. Can be detected.

  By the way, as a configuration for detecting the inclination angle of the front portion of the workpiece W, a rotation detector such as a pulse encoder may be linked to the pivot 29 instead of the linear scale 33 or the like. In addition, as schematically shown by imaginary lines in FIG. 2, it is possible to adopt a configuration in which a weight 41 is attached to the rotation shaft of the rotation detector 39 such as a pulse encoder magnetically attached to the workpiece W by a magnet Mg. It is. That is, various configurations can be adopted as the configuration of the rotation angle detection means for detecting the rotation angle (inclination angle) in the upward direction with respect to the horizontal of the front portion (the same applies to the rear portion) of the workpiece W. is there.

  In order to detect the inclination angle θ of the bisector LB that bisects the bending angle A of the workpiece W with respect to the vertical line LA passing through the center in the width direction (front-rear direction) of the bending groove DV provided in the die D In addition, an inclination angle detecting means 41 is provided on a part of the die D. That is, the die D is provided with a pair of distance detecting means 43A and 43B at symmetrical positions in the width direction with a center line passing through the center in the width direction of the bending groove DV as a center.

  More specifically, vertical through holes 45A and 45B are formed at symmetrical positions in the width direction of the die D, and the through holes 45A and 45B are formed on the lower surface of the workpiece W during bending. Pin-shaped contacts 47A and 47B whose upper end portions are freely contactable are inserted so as to be movable up and down. The upper ends of the pair of contacts 47A, 47B protrude into the bending groove DV in the die D, and the upper ends thereof are at a height position substantially equal to the upper surface of the die D in a normal state.

  In the arrangement space 49 provided on the lower side of the die D, a pair of linear sensors 51A and 51B for detecting the vertical movement of the contacts 47A and 47B are arranged, and the contacts 47A. , 47B are elastic members 53A, 53B such as coil springs for pressing upward.

  Accordingly, when the workpiece W placed horizontally on the die D is pressed by the punch P and bent, the amount of the workpiece W entering the bending groove DV of the die D is determined by the linear sensors 51A and 51B. It can be detected. Therefore, the inclination angle θ of the bisector LB with respect to the vertical line LA can be detected by obtaining the difference between the detection values of the linear sensors 51A and 51B.

  In addition, as a configuration for detecting the amount of work W entering the bending groove DV of the die D, instead of the configuration including the contacts 47A and 47B and the linear sensors 51A and 51B, the configuration is provided at the positions of the linear sensors 51A and 51B. A distance sensor using a laser beam may be arranged to detect the amount of work W entering the bending groove DV optically.

  In order to detect the inclination angle θ of the bisector LB with respect to the vertical line LA, the linear sensors 51A and 51B are connected to a difference calculating means 55. The difference calculation means 55 calculates a difference ΔY between the detection value of the linear sensor 51A and the detection value of the linear sensor 51B.

  The detection head 37 of the linear scale 33 in the rotation angle detection device 11 is connected to angle conversion means 57 that converts the stroke value of the linear scale 33 based on the detection value of the detection head 37 into the rotation angle of the rotation detector 27. is there. Based on the rotation angle α of the rotation detector 27 obtained by the angle conversion means 57 and the difference ΔY, the calculation means 59 calculates the inclination angle θ, and the inclination angle θ and the rotation detector. The bending angle A of the workpiece W is calculated based on the rotation angle α of 27.

  The inclination angle θ is expressed as θ≈f (ΔY, α) as a function of the difference ΔY and the rotation angle α, and the bending angle A of the workpiece W is in the range of 75 ° to 100 °. In this case, it is expressed as θ≈f (ΔY). The inclination angle θ at the time of actual bending of the workpiece W is about 3 ° or less and very small, and is very small with respect to the rotation angle α of the rotation detector 27. θ is expressed as θ = KΔY (K: coefficient).

  Here, when the relationship between the coefficient K and the rotation angle α of the rotation detector 27 is obtained by actual measurement, the relationship is as shown in FIG. Therefore, the relationship between the coefficient K and the rotation angle α is provided as a data table in advance as a data table 61.

  Therefore, the calculation means 59 calculates the tilt angle θ based on the difference ΔY between the detection values of the linear sensors 51A and 51B, the rotation angle α of the rotation detector 27, and the coefficient K stored in the data table 61. The bending angle A of the workpiece W is calculated based on the inclination angle θ and the rotation angle α. In addition, since the angle A can be obtained geometrically, the description of how to obtain it is omitted.

  In the configuration as described above, when the workpiece W is placed horizontally on the die D, the lifting beam 13 is raised by the lever 19 when the rotating shaft 17 of the lifting mechanism 15 is rotated in the clockwise direction. Therefore, the elevating member 23 in the rotation angle detecting device 11 is raised via the elastic support means 25. When the contact surface 27A of the rotation detector 27 is in contact with the lower surface of the workpiece W, the elastic support means 25 is compressed, and the elevating beam 13 and the base member 21 are relatively raised with respect to the elevating member 23. Is.

  As described above, when the workpiece W is horizontally placed on the die D and the contact surface 27A of the rotation detector 27 is in contact with the lower surface of the workpiece W, the punch P in the press brake is relatively lowered. When the workpiece W is pressurized, a part of the workpiece W is pressed into the bending groove DV of the die D, and the workpiece W is bent.

  When a part of the workpiece W enters the bending groove DV of the die D, the pair of contacts 47A and 47B provided on the die D are pressed downward by the workpiece W, and resist the urging force of the elastic members 53A and 53B. Is lowered. The descending amounts of the pair of contacts 47A, 47B are detected by the linear sensors 51A, 51B, and the difference ΔY between the detected values is calculated by the difference calculating means 55.

  As described above, when a part of the workpiece W is pressed into the bending groove DV of the die D by the punch P and bending of the workpiece W is started, the front side portion and the rear side portion of the workpiece W are moved upward. The workpiece W is gradually rotated, and the workpiece W is bent into a V shape. At this time, the elevating member 23 is biased upward by the elastic support means 25, and the contact surface 27A of the rotary contact 27 is always in contact with the lower surface of the front portion of the work W. The upward rotation angle of the front portion, that is, the inclination angle α of the front portion is detected by the follow-up rotation of the rotary contactor 27.

  Then, the inclination angle θ is calculated based on the difference ΔY, the rotation angle α of the rotary contact 27, and the coefficient K of the data table 61, and the workpiece W is bent based on the inclination angle θ and the rotation angle α. The angle A is required. That is, the bending angle A of the workpiece W can be accurately detected with a configuration in which the rotation angle detection device 11 is arranged on one side of the front side or the rear side of the die D.

  In other words, since it is not necessary to arrange the rotation angle detection devices 11 on both the front and rear sides of the die D, for example, by providing a rising portion, the rising portion of the work that has been bent into an L shape in advance is placed on the lower side. Even when bending is performed, the workpiece W can be bent without causing any problem, and the bending angle of the workpiece W can be accurately detected. The conventional problems can be solved.

  By the way, in the above description, a case has been described in which the die D is provided with a pair of contacts 47A and 47B and the rotation angle detection device 11 is provided separately from the die D.

  However, a plate-like bracket 59 (see FIG. 4) that can be freely arranged is provided between the divided dies D, and the rotation angle detection device 11 can be moved up and down on the bracket 59, and the inclination angle detection means 41 is provided. The bracket 59 may be provided. In other words, the rotation angle detection device 11 and the tilt angle detection means 41 can be configured as a unit. Note that components having the same functions as those described above are denoted by the same reference numerals, and redundant description is omitted.

  With the above configuration, the bracket 59 is disposed between the divided dies D, whereby the rotation angle detection device 11 and the inclination angle detection means 41 can be easily disposed at a plurality of locations. . Moreover, since it is not necessary to provide the through holes 45A and 45B in the die D, it can be easily arranged between the conventional divided dies, and can be easily applied to a conventional press brake.

  5 to 7 show a second embodiment of the tilt angle detecting means 41.

  The inclination angle detecting means 61 according to the second embodiment is mounted on a bracket or die D that can be arranged between the divided dies D. In this example, a configuration in which the die D is provided with the tilt angle detecting means 61 is illustrated, but when the die D is formed thin, the die D corresponds to the bracket.

  The inclination angle detecting means 61 includes a pair of plate-like guide members 63 fixed to the die D, and a base block 65 is integrally fixed to a lower portion between the pair of guide members 63. Above the base block 65, a box-shaped elevating member 67 is provided so as to be movable up and down. An appropriate elastic support member 68 such as a coil spring that elastically supports the elevating member 67 is interposed between the base block 65 and the elevating member 67.

  A T-shaped swing member 71 is swingably supported by the elevating member 67 via a hinge pin 69. The hinge pin 69 is positioned horizontally in a vertical plane (a vertical line in a side view) passing through the center of the bending groove DV in the die D in the width direction. Between the swing member 71 and the elevating member 67, the upper surface of the swing member 71 is always held horizontally and the hanging portion 71A of the T-shaped swing member 71 is held vertically. Elastic members 73A and 73B such as a pair of coil springs are interposed.

  At the symmetrical position on the upper surface of the swing member 71, the lower ends of the contacts 75A and 75B corresponding to the contacts 47A and 47B are in contact. A linear sensor 77 such as a potentiometer is mounted on the elevating member 67, and an actuator (not shown) movably provided on the linear sensor 77 and a lower end portion of the hanging portion 71A are rod members. And are connected via an appropriate connecting member (not shown) such as a string-like member.

  Therefore, in the above configuration, when the work W is placed on the die D and bent, the pair of contacts 75A and 75B are lowered by a part of the work entering the bending groove DV of the die D. Pressed in the direction. Here, when the pair of contacts 75A and 75B are equally pressed down, the swinging member 71 does not swing and the downward pressing force is transmitted to the lifting member 67 through the hinge pin 69. The elevating member 67 is lowered against the urging force of the elastic support member 68. At this time, since the swing member 71 does not swing, the linear sensor 77 is positioned at the neutral position, and detects that the inclination angle θ of the bisector of the bending angle of the workpiece is zero. is there.

  When the work W is bent, the bisector that bisects the bending angle of the work is inclined with respect to the vertical, so that the downward pressing amount of the pair of contacts 75A and 75B is different. The swinging member 71 is pivoted and pivoted in the clockwise direction or the counterclockwise direction in FIG. 7 around the hinge pin 69, so that the rotational direction and the amount of rotation are detected by the linear sensor 77. Is. Therefore, the inclination direction and the inclination angle of the bisector can be detected from the detection value of the linear sensor 77.

  In the above configuration, since the difference in the operation amount between the pair of contacts 75A and 75B is detected as the swing angle of the swing member 71, only one linear sensor 77 is required. It is an inexpensive configuration.

It is a schematic explanatory drawing of the press brake which concerns on embodiment of this invention. It is explanatory drawing which illustrated notionally and schematically the whole structure of the bending angle detection apparatus. It is explanatory drawing of the content of a data table. It is explanatory drawing which shows the 2nd example of a bending angle detection apparatus. It is perspective explanatory drawing which shows the 2nd example of an inclination angle detection means. It is perspective explanatory drawing of the 2nd inclination detection means which removed a part and showed the inside. It is perspective explanatory drawing of the 2nd inclination detection means which removed a part and showed the inside. It is perspective explanatory drawing which showed the structure of the conventional bending angle detection apparatus roughly.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Press brake 3 ... Upper table 5 ... Lower table 11 ... Rotation angle detector 13 ... Elevating beam 15 ... Elevating mechanism 21 ... Base member 23 ... Elevating member 25 ... Elastic support means 27 ... Rotation detector 33 ... Linear scale 37 ... Detection head 41 ... Inclination angle detection means 43A, B ... Distance detection means 47A, B ... Contact 51A, B ... Linear sensor 55 ... Difference calculation means 57 ... Angle conversion means 59 ... Calculation means 60 ... Data table 61 ... Inclination angle detection Means 67 ... Lifting member 71 ... Swing member 75A, B ... Contact 77 ... Linear sensor

Claims (8)

  A method for detecting a bending angle of a workpiece when the workpiece is bent by a press brake, wherein the workpiece is bent with respect to a vertical line passing through a center in a width direction of a bending groove in a die provided for the press brake. Detecting a tilt angle of a bisector that bisects the angle, detecting a rotation angle of the workpiece with respect to the horizontal, and detecting a bending angle of the workpiece based on the tilt angle and the rotation angle. A bending angle detection method characterized by the above.   A bending angle detection device for detecting a bending angle of a workpiece to be bent by a press brake, wherein the workpiece is bent with respect to a vertical line passing through a center in a width direction of a bending groove in a die provided for the press brake. A bending angle comprising: an inclination angle detecting means for detecting an inclination angle of a bisector of the bending angle; and a rotation angle detecting means for detecting the rotation angle of the workpiece with respect to the horizontal. Detection device.   3. The bending angle detection device according to claim 2, wherein the tilt angle detection means is a pair of distance detections arranged at symmetrical positions in the width direction with a center line passing through the center in the width direction of the bending groove in the die as a center. A bending angle detecting device comprising means.   3. The bending angle detecting device according to claim 2, wherein the inclination angle detecting means includes a pair of contacts arranged at symmetrical positions in the width direction around a center line passing through a center in the width direction of the bending groove in the die. The upper ends of the pair of contacts are provided so as to be freely contactable with the lower surface of the workpiece during bending, and the lower ends of the pair of contacts are supported by a swinging member provided so as to be swingable. A bending angle detection device comprising a swing angle detecting means for detecting the swing angle of the swing member.   5. The bending angle detection device according to claim 2, 3 or 4, wherein the rotation angle detection means includes a rotation detector which can be raised and rotated following the upward rotation of the workpiece. A bending angle detection device characterized by comprising:   A bending angle detection device for detecting a bending angle of a workpiece to be bent by a press brake, wherein a bracket that can be disposed between dies mounted on a lower table in the press brake is provided, and the press brake is provided. Inclination angle detection means for detecting the inclination angle of the bisector of the bending angle of the workpiece with respect to a vertical line passing through the center in the width direction of the bending groove in the equipped die, and detecting the rotation angle of the workpiece with respect to the horizontal A bending angle detection device comprising: the rotation angle detection means for performing the operation on the bracket.   A die for use in a press brake, and an inclination angle detecting means for detecting an inclination angle of a bisector of a bending angle of a workpiece with respect to a vertical line passing through a center in a width direction of a bending groove provided in the die. A die characterized by comprising. In a press brake comprising an upper table having a punch for bending a workpiece and a lower table having a die corresponding to the punch, and one of the upper and lower tables being freely movable up and down. A tilt angle detecting means for detecting a tilt angle of a bisector of a bending angle of the workpiece with respect to a vertical line passing through a center in a width direction of a bending groove in the die, and detecting a rotation angle of the workpiece with respect to the horizontal. A plurality of bending angle detection devices each having a rotation angle detection means for appropriately separating the rotation angle in the longitudinal direction of the die on the lower table, and detecting the rotation angle in each of the bending angle detection devices. A press brake characterized in that the lower table is provided with vertical operating means for moving the means up and down simultaneously.

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