Patent Publication Number: US-2022226876-A1

Title: Press brake

Description:
TECHNICAL FIELD 
     The present invention relates to a press brake that bends a plate-shaped workpiece by cooperation of an upper tool and a lower tool. 
     BACKGROUND ART 
     Patent Literature 1 discloses a press brake equipped with an auto tool changer (ATC). In the press brake, an upper tool changing unit that automatically changes an upper tool is attached to a back side of an upper table. In this case, a modular type upper tool holder including the upper tool changing unit mounted thereto and extending in a left-right direction is often provided in a lower end portion (lower end side) of the upper table. In the modular type upper tool holder, a guide member supporting the upper tool changing unit movably in the left-right direction is provided on a back side of the upper table. The guide member extends in the left-right direction. The guide member is provided directly in the modular type upper tool holder, and hence parallelism of the guide member to the modular type upper tool holder can be kept with high accuracy. 
     On the other hand, in many of stand-alone press brakes each of which is not equipped with the ATC, a plurality of fixture plates are arranged at intervals in the left-right direction on a front surface of the upper table. On the lower end side of the upper table, a plurality of general-purpose upper tool holder referred to as distance-piece type holders are arranged at intervals in the left-right direction. Each general-purpose upper tool holder includes an attachment plate to be pressed onto the front surface of the upper table with the fixture plates. That is, on the lower end side of the front surface (front lower end portion) of the upper table, general-purpose upper tool holders are arranged at intervals in the left-right direction via the fixture plates. 
     To avoid interference of a side flange with a part (upper tool holder or the like) of the press brake due to folding-up of a workpiece during bending of the workpiece, an escape space is formed between the upper tool holders adjacent to each other. The side flange is a flange of the workpiece that is bent on one side or both sides in the left-right direction. Further, the general-purpose upper tool holder is usually disposed at a position adjustable in the left-right direction relative to the upper table so that the interference of the side flange with the part of the press brake can be avoided even when the side flange is disposed at an arbitrary position in the left-right direction relative to the upper table. As patent literatures related to background art, there are also Patent Literatures 2 to 6 as follows. 
     CITATION LIST 
     Patent Literature 
     
         
         Patent Literature 1: Japanese Patent Publication No. 4672868 
         Patent Literature 2: Japanese Patent Publication No. 5841800 
         Patent Literature 3: Japanese Patent Publication No. 5947861 
         Patent Literature 4: Japanese Patent Application Laid-Open Publication No. 2003-71519 
         Patent Literature 5: Japanese Patent Application Laid-Open Publication No. 2015-120185 
         Patent Literature 6: Japanese Patent Application Laid-Open Publication No. 2004-344918 
       
    
     SUMMARY 
     In recent years, it has been desired that a stand-alone press brake is equipped with ATC. In a case where an upper tool changing unit is to be disposed on a back side of an upper table in the stand-alone press brake, a guide member cannot be attached directly to an upper tool holder due to space constraints. Also, there is a concern that the upper tool holder interferes with the upper tool changing unit, and hence it is also difficult to attach the guide member directly to a back surface of the upper table. Consequently, it is presumed that a plurality of connecting members are arranged at intervals in a left-right direction on a lower end side of the back surface of the upper table, and that guide members extending in the left-right direction are integrally coupled to distal-end faces of the plurality of connecting members. 
     In this case, an attachment reference surface of the upper tool holder in a front-rear direction is a machining-finished surface of the upper table on a front lower end side. An attachment surface of the guide member is a distal-end face of each connecting member, and an attachment reference surface of the guide member in the front-rear direction is a machining-finished surface of the upper table on a back lower end side to which each connecting member is attached. That is, the attachment reference surface of the upper tool holder is different from the attachment reference surface of the guide member. Consequently, in a case of equipping the stand-alone press brake with the upper tool changing unit, it is not easy to keep parallelism of the guide member to the upper tool holder with high accuracy. As a result, it is difficult to sufficiently secure reliability of a changing operation by the upper tool changing unit. This occurs similarly also in a case where a moving body other than the upper tool changing unit is supported movably in the left-right direction by the guide member on a back side of the upper table in the stand-alone press brake. 
     An object of the present invention is to provide a press brake in which an attachment reference surface of an upper tool holder and an attachment reference surface of a guide member can be the same. 
     As a first feature of the present invention, provided is a press brake including an attachment base provided on a front surface of an upper table, extending in a left-right direction, and including a plurality of protruding tabs protruding downward and formed at intervals in the left-right direction, an upper tool holder disposed between protruding tabs adjacent to each other in the left-right direction in a front surface of the attachment base, and holding an upper tool, a plurality of connecting members attached to back surfaces of the plurality of protruding tabs, respectively, and including distal ends located on a back side of the upper table, and a guide member coupled to distal-end faces of the plurality of connecting members, extending in the left-right direction, and supporting a moving body movably in the left-right direction on the back side of the upper table. 
     Also, due to bending load (bend pressurizing force) during bending of a workpiece, a lower surface of the upper table tends to be deflected in a concave shape, and an upper surface of a lower table tends to be deflected in a concave shape. If the deflections of the upper table and the lower table are large, side misalignment (positional shift in the left-right direction) of a general-purpose upper tool holder to the upper table is likely to occur. If the misalignment occurs, interference of a side flange with a part of the press brake and bending defect occur, and highly accurate bending cannot be stably performed. This similarly occurs not only in a press brake equipped with an ATC but also in a stand-alone press brake that is not equipped with the ATC. That is, it is required to regulate the side misalignment of the upper tool holder to the upper table. 
     As a second feature of the present invention, provided is a press brake including a plurality of fixture plates (fastening plates) arranged at intervals in a left-right direction on a front surface of an upper table, a plurality of upper tool holders arranged at intervals in the left-right direction on a lower end side of the upper table, including an attachment plate to be pressed onto a front side of the upper table by each fixture plate, and holding an upper tool, and a regulating member disposed on each of opposite left and right sides of each upper tool holder in the upper table, and configured to regulate side misalignment (positional shift in the left-right direction) of the upper tool holder to the upper table. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic front view showing a press brake according to a first embodiment. 
         FIG. 2  is an enlarged view of part II in  FIG. 1 . 
         FIG. 3  is an enlarged view of part III in  FIG. 2 . 
         FIG. 4  is a cross-sectional view along the IV-IV line in  FIG. 2 . 
         FIG. 5  is a cross-sectional view along the V-V line in  FIG. 2 . 
         FIG. 6  is a partial front view showing an attachment base. 
         FIG. 7  is a schematic front view showing a press brake according to a second embodiment. 
         FIG. 8  is an enlarged view of part VIII in  FIG. 7 . 
         FIG. 9  is an enlarged cross-sectional view along the IX-IX line in  FIG. 8 . 
         FIG. 10  is a partial front view showing a press brake according to a first modification of the second embodiment. 
         FIG. 11  is an enlarged cross-sectional view along the XI-XI line in  FIG. 10 . 
         FIG. 12  is a partial front view showing a press brake according to a second modification of the second embodiment. 
         FIG. 13  is an enlarged cross-sectional view along the XIII-XIII line in  FIG. 12 . 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Embodiments (including modifications) of the present invention will be described with reference to  FIG. 1  to  FIG. 6 . 
     Note that “a lateral direction” includes meanings of a lateral direction of an upper tool, a lateral direction of a lower tool, a lateral direction of an upper tool holder, and a lateral direction of a press brake unless otherwise noted. “A left-right direction” is one of horizontal directions, and is the same as the lateral direction of the press brake. “A front-rear direction” is one of the horizontal directions, and a direction orthogonal to the left-right direction. “A pressurizing center position” refers to a position of a virtual vertical plane passing through a distal end of a punch in the front-rear direction. In the drawings, “L” indicates a left direction, “R” indicates a right direction, “FF” indicates a front direction, “FR” indicates a rear direction, “U” indicates an up direction, and “D” indicates a down direction. 
     First Embodiment 
     As shown in  FIG. 1  and  FIG. 2 , a press brake  10  according to a first embodiment is a processing machine that performs bending of a plate-shaped workpiece (sheet metal) W by cooperation of an automatically changeable upper tool (punch)  12  and a lower tool (die)  14 . An engagement hole  12   h  is formed through a center of the upper tool  12  in the left-right direction (lateral direction). In a shank  12   s  (see  FIG. 4 ) of the upper tool  12 , an anti-drop groove  12   g  (see  FIG. 4 ) is formed along the left-right direction. An engagement hole  14   h  is formed through a center of the lower tool  14  in the left-right direction. 
     The press brake  10  includes a main frame  16 . The main frame  16  includes a pair of side plates  18  separated from and opposed to each other in the left-right direction, and a plurality of beam members  20  (only one is shown in the drawing) coupling the pair of side plates  18 . In a lower part of the main frame  16 , a lower table  22  extending in the left-right direction is provided. In an upper part of the main frame  16 , an upper table  24  extending in the left-right direction is vertically movably provided. In each of upper parts of the side plates  18 , a hydraulic cylinder  26  is provided as a vertically-driving actuator that vertically moves the upper table  24  relative to the main frame  16 . Note that instead of configuring the upper table  24  to be vertically movable, the lower table  22  may be configured to be vertically movable. As the vertically-driving actuator, a servo motor may be used in place of the hydraulic cylinder  26 . 
     As shown in  FIG. 2  to  FIG. 6 , on a lower end side of a front surface of the upper table  24 , a machining-finished surface  24   f  is formed along the left-right direction. A plate-shaped attachment base  28  extending in the left-right direction is attached to the machining-finished surface  24   f  of the upper table  24  with a plurality of attachment bolts  30 . Each attachment bolt  30  penetrates a bolt hole  28   h  formed in the attachment base  28 . The attachment base  28  has a front surface and a back surface that are finished by machining. On a lower end side of the attachment base  28 , a plurality of protruding tabs (protrusions)  32  protruding downward are formed at even intervals in the left-right direction. Note that the plurality of protruding tabs  32  may only be arranged at intervals in the left-right direction, and do not have to be arranged at even intervals. 
     A plurality of fixture plates (fastening plates)  34  are attached to the front surface of the attachment base  28  at intervals in the left-right direction with attachment bolts  36 . That is, on the front surface of the upper table  24 , the fixture plates  34  are arranged at intervals in the left-right direction via the attachment base  28  and the attachment bolts  36 . At a lower end of a back surface of each fixture plate  34 , a pawl  34   c  is formed along the left-right direction. Each attachment bolt  36  penetrates a bolt hole  28   v  formed in the attachment base  28 . 
     On a lower end side of the upper table  24 , upper tool holders  38  removably holding the upper tool  12  are arranged at intervals in the left-right direction. Each upper tool holder  38  includes an attachment plate  40  to be pressed onto the front surface of the upper table  24  with the fixture plate  34 . That is, on the lower end side of the upper table  24 , the upper tool holders  38  are arranged at intervals in the left-right direction via the fixture plates  34 . Further, each upper tool holder  38  is disposed between the protruding tabs  32  adjacent to each other in the left-right direction in the front surface of the attachment base  28 . The upper tool holder  38  includes, for example, a configuration disclosed in Patent Literature 2 described above. The configuration of the upper tool holder  38  will be briefly described hereinafter. 
     As shown in  FIG. 2  to  FIG. 5 , in an upper part of a front surface of the attachment plate  40 , an engagement groove  40   g  to be engaged with the pawl  34   c  of each fixture plate  34  is formed. A holder main body (intermediate plate)  42  is attached to a lower part of a rear surface of the attachment plate  40  with a plurality of attachment bolts (not shown). The holder main body  42  is located on a lower side of the upper table  24 . That is, the holder main body  42  is disposed on the lower side of the upper table  24  with the attachment plate  40 . An upper surface of the holder main body  42  is formed as a tilted surface  42   f  tilted in the front-rear direction. 
     A wedge member  44  is disposed between the holder main body  42  and the upper table  24 , and disposed at position adjustable relative to the holder main body  42  in the front-rear direction. A lower surface of the wedge member  44  is formed as a tilted surface  44   f  tilted in the front-rear direction. The tilted surface  44   f  comes in sliding contact with the tilted surface  42   f  of the holder main body  42 . In a center of the attachment plate  40  in the left-right direction, a push bolt  46  for pushing the wedge member  44  rearward is disposed. On right and left sides of the push bolt  46  of the attachment plate  40 , pull bolts  48  for pulling the wedge member  44  forward are arranged, respectively. 
     A clamp plate  50  configured to press the shank  12   s  of the upper tool  12  onto the holder main body  42  is swingably attached to a front surface of the holder main body  42  with a plurality of support shafts  52 . A clamp plate  50  configured to press the shank  12   s  onto the holder main body  42  is also swingably attached to a back surface of the holder main body  42  with a plurality of support shafts  52 . On a lower end side of each clamp plate  50 , a hook member  54  engageable in the anti-drop groove  12   g  of the upper tool  12  is formed. Also, in the holder main body  42 , a clamp plate cylinder (not shown) for a pressing operation of a pair of clamp plates  50  is disposed. A spring  56  that urges each clamp plate  50  in a release direction of the pressing operation is interposed between the holder main body  42  and each clamp plate  50 . 
     As shown in  FIG. 2 ,  FIG. 3  and  FIG. 6 , in the present embodiment, the attachment plate  40  in each upper tool holder  38  is interposed between the protruding tabs  32  adjacent to each other in the left-right direction. Each protruding tab  32  of the attachment base  28  is a first regulating member that comes in contact with a side surface of the attachment plate  40  to regulate side misalignment (positional shift in the left-right direction) of the upper tool holder  38 . That is, the protruding tabs  32  (first regulating members) are arranged on opposite left and right sides of each attachment plate  40  in the front surface of the upper table  24 , respectively. Also, an escape space S for avoiding interference of a side flange Wf with a part (upper tool holder  38  or the like) of the press brake  10  due to folding-up of the workpiece W is formed between the upper tool holders  38  adjacent to each other. Note that  FIG. 6  shows the upper tool holders  38  and connecting members  64  with dashed lines. 
     As shown in  FIG. 1  and  FIG. 2 , a lower tool holder  58  removably holding the lower tool  14  is provided at an upper end of the lower table  22 . The lower tool holder  58  extends in the left-right direction. The lower tool holder  58  includes, for example, a configuration disclosed in Patent Literature 1 described above. 
     As shown in  FIG. 1 , the press brake  10  is equipped with an auto tool changer (ATC)  60  for automatically changing the upper tool  12  and the lower tool  14 . On one side (right side) of the main frame  16  of the ATC  60  in the left-right direction, a tool storage  62  that stores a plurality of upper tools  12  and a plurality of lower tools  14  is disposed. The tool storage  62  includes, for example, a configuration disclosed in Patent Literatures 1, 3 and 4 described above. The tool storage  62  includes, in an upper part, a plurality of upper stockers (not shown) holding the plurality of upper tools  12 . The selected upper stocker is positioned at an upper tool exchange position located on a side of the upper tool holder  38 . Also, the tool storage  62  includes, in a lower part, a plurality of lower stockers (not shown) holding a plurality of lower tools  14 . The selected lower stocker is positioned at a lower tool exchange position located on a side of the lower tool holder  58 . 
     As shown in  FIG. 2  to  FIG. 6 , the rectangular plate-shaped connecting members  64  are attached to back surfaces of the respective protruding tabs  32  of the attachment base  28  with a plurality of attachment bolts  66 . Each attachment bolt  66  penetrates a bolt hole  28   b  formed in the attachment base  28 . Each connecting member  64  on a distal end side (rear end side) is located on a back side of the upper table  24 . Each connecting member  64  has a base-end face (front end face) and a distal-end face (rear end face) finished by machining. To prevent deflection of the connecting members  64 , the connecting members  64  are coupled to a lower end face of the upper table  24  with a plurality of coupling bolts  68 . Each connecting member  64  is a second regulating member that comes in contact with a side surface of the holder main body  42  to regulate side misalignment of the upper tool holder  38 . That is, the connecting members  64  (second regulating members) are arranged on opposite left and right sides of the upper tool holder  38  on the lower end side of the upper table  24 , respectively. 
     As shown in  FIG. 1 ,  FIG. 4  and  FIG. 5 , an upper guide member  70  extending in the left-right direction is integrally coupled to a rear end face of the connecting member  64  with a coupling bolt  72 . The upper guide member  70  has a left end protruding leftward from the upper table  24 . The upper guide member  70  has a right end protruding rightward from the upper table  24 , and overlapping with the tool storage  62 . The upper guide member  70  includes, on a back surface, a rail  70   r  extending in the left-right direction. Also, on the rail  70   r , a pair of upper tool changing units  74  for automatically changing the upper tool  12  are provided movably in the left-right direction. That is, the upper guide member  70  supports the pair of upper tool changing units  74  as moving bodies movably in the left-right direction on the back side of the upper table  24 . Each upper tool changing unit  74  can remove the upper tool  12  from the upper tool holder  38  (or the upper stocker positioned at the upper tool exchange position) in the front-rear direction and left-right direction. Also, the upper tool changing unit  74  can attach the upper tool  12  to the upper tool holder  38  (or the upper stocker positioned at the upper tool exchange position) in the front-rear direction and left-right direction. 
     The upper tool changing unit  74  includes, for example, a configuration disclosed in Patent Literature 1 described above. The upper tool changing unit  74  includes an upper unit main body  76  provided movably in the left-right direction on the rail  70   r  of the upper guide member  70 , and an upper tool retention member  78  provided in the upper unit main body  76 . The upper tool retention member  78  is a rod-shaped or hook-shaped member engageable in the engagement hole  12   h  of the upper tool  12 . The upper tool retention member  78  is configured to be movable in the front-rear direction and up-down direction relative to the upper unit main body  76 . Note that the upper tool retention member  78  does not have to be movable vertically to the upper unit main body  76 . A changing operation by the upper tool changing units  74  is not described. 
     As shown in  FIG. 1 , a lower guide member  80  extending in the left-right direction is attached to a back surface of the lower tool holder  58 . The lower guide member  80  has a left end protruding leftward from the lower table  22 . The lower guide member  80  has a right end protruding rightward from the lower table  22 , and overlapping with a tool storage  62  side. In the lower guide member  80 , a pair of lower tool changing units  82  for automatically changing the lower tool  14  are provided movably in the left-right direction. Each lower tool changing unit  82  can remove the lower tool  14  from the lower tool holder  58  (or the lower stocker positioned at the lower tool exchange position) in the front-rear direction and left-right direction. Also, the lower tool changing unit  82  can attach the lower tool  14  to the lower tool holder  58  (or the lower stocker positioned at the lower tool exchange position) in the front-rear direction and left-right direction. 
     The lower tool changing unit  82  includes, for example, a configuration disclosed in Patent Literature 1 described above. The lower tool changing unit  82  includes a lower unit main body  84  provided movably in the left-right direction in the lower guide member  80 , and a lower tool retention member  86  provided in the lower unit main body  84 . The lower tool retention member  86  is a rod-shaped or hook-shaped member engageable in the engagement hole  14   h  of the lower tool  14 . The lower tool retention member  86  is configured to be movable in the front-rear direction and a direction relative to the lower unit main body  84 . Note that a changing operation by the lower tool changing units  82  is not described. 
     Subsequently, description will be made as to effects of the present embodiment. 
     In the present embodiment, the attachment base  28  is provided on the lower end side of the front surface of the upper table  24 , and the upper tool holder  38  is disposed between the protruding tabs  32  adjacent to each other in the left-right direction in the front surface of the attachment base  28 . That is, the upper tool holder  38  is attached to the lower end side of the front surface of the upper table  24  via the attachment base  28 . The attachment surface of the upper tool holder  38  is the front surface of the attachment base  28 , and the attachment reference surface of the upper tool holder  38  in the front-rear direction is the machining-finished surface  24   f  of the upper table  24  on the lower end side of the front surface. 
     Further, in the present embodiment, the connecting member  64  is attached to the back surface of each protruding tab  32  of the attachment base  28 , and the upper guide member  70  is integrally coupled to the distal-end face of each connecting member  64 . That is, the upper guide member  70  is attached to the lower end side of the front surface of the upper table  24  via the connecting member  64  and the attachment base  28 . The attachment surface of the upper guide member  70  is the distal-end face of the connecting member  64 , and hence the attachment reference surface of the upper guide member  70  in the front-rear direction is the machining-finished surface  24   f  of the upper table  24  on the lower end side of the front surface via the connecting member  64 . 
     Therefore, according to the present embodiment, the attachment reference surface of the general-purpose upper tool holder and the attachment reference surface of the upper guide member can be the same. Also, according to the present embodiment, in the case of equipping the stand-alone press brake  10  with the upper tool changing unit  74  as the moving body, parallelism of the upper guide member  70  to the upper tool holders  38  can be kept with high accuracy, and reliability of the changing operation by the upper tool changing unit  74  can be sufficiently secured. 
     Further, in the present embodiment, the protruding tabs  32  (first regulating members) are arranged on the opposite left and right sides of the attachment plate  40  in the front surface of the upper table  24 , respectively. The connecting members  64  (second regulating members) are arranged on the opposite left and right sides of each upper tool holder  38  on the lower end side of the upper table  24 , respectively. Therefore, even when the deflections of the upper table  24  and the lower table  22  increase due to the bending load during the bending of the workpiece W, the protruding tabs  32  and the connecting members  64  can regulate (prevent) the side misalignment of the upper tool holder  38  to the upper table  24 . As a result, the reliability of the changing operation by the upper tool changing unit  74  can be more sufficiently secured. Also, bending defect can be prevented, and the bending can be performed with high accuracy and stability, while avoiding the interference of the side flange Wf with the upper tool holder  38  or the like. 
     Second Embodiment 
     As shown in  FIG. 7  to  FIG. 9 , a press brake  88  according to a second embodiment is a processing machine that performs bending of a plate-shaped workpiece (sheet metal) W by cooperation of an upper tool  12  and a lower tool  14 . In the present embodiment, an engagement hole  12   h  (see  FIG. 2 ) is not formed in the upper tool  12 , but the engagement hole  12   h  may be formed. An engagement hole  14   h  (see  FIG. 2 ) is not formed in the lower tool  14 , but the engagement hole  14   h  may be formed. 
     The press brake  88  includes a configuration similar to the configuration of the press brake  10  (see  FIG. 1 ) except that the press brake is not equipped with an ATC  60  (see  FIG. 1 ). Hereinafter, description will be made only as to a configuration of the press brake  88  that is different from the configuration of the press brake  10 . Note that components of the press brake  88  corresponding to the components of the press brake  10  are denoted with the same reference signs, and the components are not described in detail. 
     A lower end face of each protruding tab (protrusion)  32  of an attachment base  28  is positioned higher than a lower end face of an upper table  24 . A connecting member (see  FIG. 5 ) is not provided on a back surface of the protruding tab  32 . The protruding tab  32  is a regulating member that comes in contact with a side surface of an attachment plate  40  to regulate side misalignment (positional shift in a left-right direction) of each upper tool holder  38 . That is, the protruding tabs  32  (regulating members) are arranged on opposite left and right sides of each attachment plate  40  in a front surface of the upper table  24 , respectively. Note that the lower end face of the protruding tab  32  may be positioned as high as the lower end face of the upper table  24  instead of being positioned higher than the lower end face of the upper table  24 . 
     The upper tool holder  38  includes, for example, a mechanical type configuration disclosed in Patent Literature 5 described above. A lower tool holder  58  includes, for example, a mechanical type configuration disclosed in Patent Literature 6 described above. 
     Subsequently, description will be made as to effects of the present embodiment. 
     The protruding tabs  32  (regulating members) are arranged on the opposite left and right sides of each attachment plate  40  in the front surface of the upper table  24 , respectively. Therefore, even when deflections of the upper table  24  and a lower table  22  increase due to bending load during the bending of the workpiece W, the protruding tabs  32  can regulate (prevent) side misalignment of the upper tool holder  38  to the upper table  24 . As a result, bending defect can be prevented, and the bending of the workpiece W can be performed with high accuracy and stability, while avoiding interference of a side flange Wf with the upper tool holder  38  or the like. 
     Also, since the lower end face of each protruding tab  32  is positioned higher than the lower end face of the upper table  24 , a height of the side flange Wf is not restricted by the protruding tab  32  as the regulating member, and a degree of freedom in bending of the workpiece W can be sufficiently secured. That is, the degree of freedom in bending of the workpiece W can be sufficiently secured, and additionally, the bending of the workpiece W can be performed with high accuracy and stability. Even when the lower end face of the protruding tab  32  is positioned as high as the lower end face of the upper table  24 , the degree of freedom in bending can be sufficiently secured. If the lower end face of the protruding tab  32  is positioned lower than the lower end face of the upper table  24 , the degree of freedom in bending cannot be secured. 
     (First Modification) 
     As shown in  FIG. 10  and  FIG. 11 , a press brake  88 A according to a first modification of the second embodiment includes a configuration similar to the press brake  88  (see  FIG. 8 ). Hereinafter, description will be made only as to a configuration of the press brake  88 A that is different from the configuration of the press brake  88 . Note that components of the press brake  88 A corresponding to the components of the press brake  88  are denoted with the same reference signs, and the components are not described in detail. 
     In the configuration of the press brake  88 A, the attachment base  28  (see  FIG. 8 ) is omitted. A plurality of fixture plates  34  are attached to a lower end side of a front surface of an upper table  24  at intervals in a left-right direction with attachment bolts  36 . The fixture plates  34  are fixed directly to the front surface of the upper table  24 . (An upper part of each fixture plate  34  is thicker only as much as a thickness of the attachment base  28 .) 
     Rectangular plate-shaped regulating members  90  are attached to opposite left and right sides of each upper tool holder  38  in the front surface of the upper table  24  with attachment bolts  92 . Each regulating member  90  comes in contact with a side surface of an attachment plate  40  to regulate side misalignment (positional shift in a left-right direction) of the upper tool holder  38 . A lower end face of the regulating member  90  is positioned higher than a lower end face of the upper table  24 . Note that the lower end face of the regulating member  90  may be positioned as high as the lower end face of the upper table  24  instead of being positioned higher than the lower end face of the upper table  24 . 
     Subsequently, description will be made as to effects of the present modification. 
     The regulating members  90  are arranged on the opposite left and right sides of each upper tool holder  38  in the front surface of the upper table  24 , respectively. Therefore, even when deflections of the upper table  24  and a lower table  22  increase due to bending load during the bending of a workpiece W, the regulating members  90  can regulate side misalignment of the upper tool holder  38  to the upper table  24 . As a result, bending defect can be prevented, and the bending of the workpiece W can be performed with high accuracy and stability, while avoiding interference of a side flange Wf with the upper tool holder  38  or the like. 
     Also, since the lower end face of each regulating member  90  is positioned higher than the lower end face of the upper table  24 , a height of the side flange Wf is not restricted by the regulating member  90 , and a degree of freedom in bending of the workpiece W can be sufficiently secured. That is, the degree of freedom in bending of the workpiece W can be sufficiently secured, and additionally, the bending of the workpiece W can be performed with high accuracy and stability in the same manner as in the aforementioned second embodiment. Even when the lower end face of the regulating member  90  is positioned as high as the lower end face of the upper table  24 , the degree of freedom in bending can be sufficiently secured. If the lower end face of the regulating member  90  is positioned lower than the lower end face of the upper table  24 , the degree of freedom in bending cannot be secured. 
     (Second Modification) 
     As shown in  FIG. 12  and  FIG. 13 , a press brake  88 B according to a second modification of the second embodiment includes a configuration similar to the press brake  88  (see  FIG. 8 ). Hereinafter, description will be made only as to a configuration of the press brake  88 B that is different from the configuration of the press brake  88 . Note that components of the press brake  88 B corresponding to the components of the press brake  88  are denoted with the same reference signs, and the components are not described in detail. 
     In the configuration of the press brake  88 B, the attachment base  28  (see  FIG. 8 ) is omitted. A plurality of fixture plates  34  are attached to a lower end side of a front surface of an upper table  24  at intervals in a left-right direction with attachment bolts  36 . The fixture plates  34  are fixed directly to the front surface of the upper table  24 . (An upper part of each fixture plate  34  is thicker only as much as a thickness of the attachment base  28 .) 
     Further, L-shaped regulating members  94  are attached on opposite left and right sides of each upper tool holder  38  on a lower end side of a back surface of the upper table  24  with attachment bolts  96 . Each regulating member  94  comes in contact with a side surface of a wedge member  44  to regulate side misalignment (positional shift in the left-right direction) of each upper tool holder  38 . The regulating member  94  includes a vertical part  94   a  fixed to the back surface of the upper table  24  with the attachment bolt  96 , and a horizontal part  94   b  protruding forward from a lower end of the vertical part  94   a . A front (front surface) of the horizontal part  94   b  of the regulating member  94  is located behind a pressurizing center position BL. 
     Subsequently, description will be made as to operations and effects of the present modification. 
     The regulating members  94  are arranged on the opposite left and right sides of each upper tool holder  38  on the lower end side of the back surface of the upper table  24 , respectively. Therefore, even when deflections of the upper table  24  and a lower table  22  increase due to bending load during bending of a workpiece W, the regulating members  94  can regulate side misalignment of the upper tool holder  38  to the upper table  24 . As a result, bending defect can be prevented, and the bending of the workpiece W can be performed with high accuracy and stability, while avoiding interference of a side flange Wf with the upper tool holder  38  or the like. 
     Also, since the front of the horizontal part  94   b  of the regulating member  94  is located behind the pressurizing center position BL, a height of the side flange Wf is not restricted by the regulating member  94 , and a degree of freedom in bending of the workpiece W can be sufficiently secured. That is, the degree of freedom in bending of the workpiece W can be sufficiently secured, and additionally, the bending of the workpiece W can be performed with high accuracy and stability in the same manner as in the aforementioned second embodiment. 
     Entire contents of Japanese Patent Application No. 2019-87437 (filed on May 7, 2019) and Japanese Patent Application No. 2020-71715 (filed on Apr. 13, 2020) are incorporated in the present description by reference. The present invention is described above with reference to the embodiments of the present invention, but the present invention is not limited to the aforementioned embodiments. For example, a monitor camera or a bending indicator (bend angle detector) may be used as a moving body. The scope of the present invention is determined in light of claims.