Sheet material bending system

Abstract

A sheet material bending system includes a tool changing apparatus that changes tools between a press brake and a tool stocker. The tool stocker is arranged behind the press brake. To change tools from the front and rear of the tool stocker, the front and rear of the tool stocker are opened. The tool changing apparatus has a pivot that is movable in front-rear, left-right, and up-down directions and is rotatable around an axis extending in the up-down direction. A front end of the pivot is provided with tool holding units to hold tools.

Claims

1. A sheet material bending system, comprising: a press brake that has an upper table at a front upper part of left and right side frames and a lower table at a front lower part of the left and right side frames; a tool stocker that detachably stores a plurality of upper and lower tools to be, with respect to the press brake, at least one of attached, detached and changed, the plurality of upper tools being associated with the upper table and the plurality of lower tools being associated with the lower table; and a tool changing apparatus that changes tools, among the plurality of upper and lower tools, between the press brake and the tool stocker, wherein the tool stocker is arranged behind the press brake, and front and rear sides of the tool stocker are open so that tools stored in the tool stocker are accessible from the front and rear sides of the tool stocker, and wherein the tool changing apparatus is configured to attach, detach and change the tools with respect to the tool stocker from the front side of the tool stocker, wherein the tool changing apparatus has a pair of pivots spaced apart from each other in the left-right direction, each pivot being movable in front-rear, left-right, and up-down directions and rotatable around a respective axis extending in the up-down direction, and an axial end of each pivot being provided with tool holding units to hold tools among the plurality of upper and lower tools, and wherein the tool holding units of each pivot are deviated from the respective axis of the corresponding pivot, and wherein each of the tool holding units are offset from one another as viewed in a plan view corresponding to a plane extending perpendicular to the respective axis.

2. The sheet material bending system as set forth in claim 1, characterized in that the tool stocker is arranged between the left and right side frames.

3. The sheet material bending system as set forth in claim 1, wherein each pivot is provided with a work contact member that comes into contact with and positions a work to be bent by the upper and lower tools.

4. The sheet material bending system as set forth in claim 3, wherein for each of the pivots, an end of a hook member of one of the tool holding units of the corresponding pivot is on an opposite side of the respective axis from an end of the work contact member of the corresponding pivot.

5. The sheet material bending system as set forth in claim 3, wherein the work contact member of each pivot is pivotable up and down.

6. The sheet material bending system as set forth in claim 1, wherein the tool holding units of each pivot are arranged at each of symmetrical positions on each pivot.

7. The sheet material bending system as set forth claim 1, wherein a temporary tool holding unit is arranged at an intermediate position between the press brake and tool stocker and in a moving path of the tool changing apparatus, the tool changing apparatus being movable in the front-rear direction between the press brake and the tool stocker, to temporarily hold a tool to be changed by the tool changing apparatus.

8. The sheet material bending system as set forth claim 1, wherein: the tool stocker has: a plurality of tool support beams that detachably support the plurality of tools, the tool support beams being elongate in the left-right direction and movable in the up-down direction; and front and rear shutters that open and close the front and rear sides of the tool stocker; and an interlock unit is arranged to interlock the closing and opening actions of the rear shutter with the opening and closing actions of the front shutter, respectively.

9. The sheet material bending system as set forth in claim 8, wherein the interlock unit comprises a connection member, wherein the front and rear shutters are connected to front and rear parts, respectively, of the connection member, the connection member being stretched around pulleys that are rotatably provided for the tool stocker, and a switch is arranged on a handle that is used to open and close the rear shutter, the switch being used to control ON or OFF of an electromagnetic brake that is linked and connected to the pulleys.

10. The sheet material bending system as set forth in claim 1, wherein for each of the pivots, one of the tool holding units of the corresponding pivot is able to handle upper tools and the other of the tool holding units for the corresponding pivot is able to handle lower tools.

11. The sheet material bending system as set forth in claim 1, wherein a respective reference plane oriented in the up-down direction and positioned between the tool holding units of the corresponding pivot, and coinciding with the respective axis, partitions the corresponding pivot into a corresponding first region and a corresponding second region, wherein for each of the pivots, a first one of the tool holding units is provided entirely within the corresponding first region and a second one of the tool holding units is provided entirely within the corresponding second region.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is an explanatory side view illustrating a main structure of a press brake in a sheet material bending system according to a related art.

(2) FIG. 2 is an explanatory view illustrating changing a tool of the press brake in the sheet material bending system according to the related art.

(3) FIG. 3 is an explanatory view illustrating a tool changing apparatus of the press brake in the sheet material bending system according to the related art.

(4) FIG. 4 is an explanatory perspective view schematically illustrating a general structure of a sheet material bending system according to an embodiment of the present invention.

(5) FIG. 5 is an explanatory perspective view schematically illustrating essential part of the sheet material bending system with upper and lower tables of a press brake in the system being omitted.

(6) FIG. 6 is an explanatory perspective back view illustrating the sheet material bending system.

(7) FIG. 7 is an explanatory perspective view illustrating a general structure of a tool stocker.

(8) FIG. 8 is an explanatory sectional plan view illustrating essential part of the tool stocker.

(9) FIG. 9 is an explanatory sectional side view illustrating essential part of the tool stocker.

(10) FIG. 10 is an explanatory perspective view illustrating the back of the tool stocker.

(11) FIG. 11 is an explanatory plan view schematically illustrating operation of a tool changing apparatus according to a first embodiment.

(12) FIG. 12 is an explanatory perspective view illustrating a tool holding unit of the tool changing apparatus.

(13) FIG. 13 is an explanatory plan view schematically illustrating operation of a tool changing apparatus according to a second embodiment.

(14) FIG. 14 is an explanatory perspective view illustrating the tool changing apparatus according to the second embodiment.

(15) FIG. 15 is an explanatory perspective view illustrating essential part of the tool changing apparatus according to the second embodiment.

(16) FIG. 16 is an explanatory view illustrating essential part of the tool changing apparatus.

(17) FIG. 17 is an explanatory view illustrating operation of the tool changing apparatus.

(18) FIG. 18 is an explanatory view illustrating operation of the tool changing apparatus.

(19) FIG. 19 is an explanatory perspective view illustrating a tool changing apparatus according to a third embodiment.

(20) FIG. 20 is an explanatory perspective view illustrating a tool changing apparatus according to a fourth embodiment.

MODE OF IMPLEMENTING INVENTION

(21) A sheet material bending system according to an embodiment of the present invention will be explained with reference to the drawings. Structural elements whose effects are similar to those of the related art explained above are represented with like reference marks to omit overlapping explanations.

(22) Referring to FIGS. 4 and 5, the sheet material bending system according to an embodiment of the present invention includes a press brake 75 that carries out a bending process on a sheet work, a tool stocker 77 that stores a plurality of upper and lower tools (punches P and dies D) to be attached, detached, and changed with respect to the press brake 75, and a tool changing apparatus 79 that changes the punches P and dies D between the press brake 75 and the tool stocker 77.

(23) The press brake 75 has a structure similar to that of the press brake of the related art mentioned above and includes left and right side frames 3L and 3R. Arranged at front upper part of the left and right side frames 3L and 3R is an upper table 5 that is movable upward and downward. Arranged at front lower part of the left and right side frames 3L and 3R is a lower table 7. Arranged at lower part of the upper table 5 is an upper-tool attaching unit 9 that attaches, detaches, and changes the punch P. Arranged at upper part of the lower table 7 is a lower-tool attaching unit 13 that attaches, detaches, and changes the die D.

(24) For the sake of easy understanding of a general structure, FIG. 5 omits the upper and lower tables 5 and 7. A general basic structure of the press brake 75 is the same as that of the press brake 1 according to the related art explained above, and therefore, the details of the structure of the press brake 75 will not be explained.

(25) The tool stocker 77 is arranged behind the press brake 75. As illustrated in FIGS. 5 and 6, a pair of left and right guide supports 81L and 81R extending in the up-down direction are arranged at rear part of inner side faces of the left and right side frames 3L and 3R in the press brake 75. The left and right guide supports 81L and 81R have a plurality of tool support beams 83 that are movable up and down and detachably support a plurality of punches P and dies D.

(26) More precisely, as illustrated in FIG. 7, the guide supports 81L and 81R arranged at rear part of the inner side faces of the left and right side frames 3L and 3R have guide rails 85, respectively. The guide rails 85 support left and right sides of a frame 87 so that the frame 87 is movable up and down. The frame 87 supports the tool support beams 83 that are arranged in steps and horizontally extend in the left-right direction. On a top face of each of the tool support beams 83, there is formed a tool attaching groove 11 that elongates in the left-right direction to attach thereto and detach therefrom a plurality of dies D. On a bottom face of each of the tool support beams 83, there is formed a tool attaching groove 11 (refer to FIG. 8) that elongates in the left-right direction to attach thereto and detach therefrom a plurality of punches P.

(27) The tool attaching grooves 11 formed on the top and bottom faces of each of the tool support beams 83 have the same configuration as the tool attaching grooves 11 of the upper-tool attaching unit 9 according to the above-mentioned related art. The tool support beams 83 are satisfactory if they are able to support the punches P and dies D without dropping them, and therefore, the pressing-fixing pieces 31 mentioned above are omitted.

(28) To move the frame 87 up and down, the guide supports 81L and 81R are provided with an up-down actuator 89 (refer to FIG. 7) such as a fluid pressure cylinder. In the up-down actuator 89, an up-down acting element 91 such as a piston rod that moves up and down and a connection bracket 93 integral with the frame 87 are connected together. When the up-down actuator 89 is activated, the frame 87 is moved up and down, to position a required one of the tool support beam 83 at a given height.

(29) In the tool stocker 77, lower front part and lower rear part of the left and right guide supports 81L and 81R are integrally provided with front and rear covers 95F and 95R (refer to FIGS. 8 and 9) to cover lower part of an area in which the frame 87 moves up and down. In other words, upper part of the area in which the frame 87 moves up and down is not covered with the covers 95F and 95R and is open to the front and rear sides. To improve safety, front and rear shutters 97F and 97R are arranged to be movable up and down to open and close the front and rear sides of the upper part of the area in which the frame 87 moves up and down.

(30) In more detail, as illustrated in FIGS. 8 and 9, the left and right guide supports 81L and 81R have, on their front and rear faces, guide members 99 extending in the up-down direction. The guide members 99 guide and support the left and right sides of the front and rear shutters 97F and 97R so that the shutters are movable up and down. The front and rear shutters 97F and 97R are interlocked so that, when one of the shutters 97F and 97R is moved up to close the upper side of the front cover 95F, the other of the shutters 97R and 97F descends to open the upper side of the rear cover 95R. Namely, the front and rear shutters 97F and 97R are interlocked through an interlocking unit 101 so that they oppositely operate.

(31) In more detail, upper and lower parts of the left and right guide supports 81L and 81R are each provided with rotatable pulleys 103U and 103L. Around the upper and lower pulleys 103U and 103L, an endless member 105 such as a timing belt is stretched. To turn the left and right endless members 105 in synchronization, the left and right lower pulleys 103L are integrally connected to each other through an interlocking shaft 107 that elongates in the left-right direction.

(32) The front shutter 97F is connected to a front member 105F of each endless member 105 through a front L-shaped connection bracket 111F that is passed through a long hole 109 to move up and down. The long hole 109 is formed in each of the guide supports 81L and 81R and elongates in the up-down direction. Similarly, the rear shutter 97R is connected to a rear part 105R of each endless member 105 through a rear L-shaped connection bracket 111R. Accordingly, if the front shutter 97F is moved up, the rear shutter 97R moves down through the endless member 105.

(33) The structure for interlocking the front and rear 2Q shutters 97F and 97R with each other to oppositely carry out open and close actions is not limited to the above-mentioned one. Any other structure is acceptable. For example, the front and rear shutters 97F and 97R may be moved up and down with separate fluid pressure cylinders with upper or lower cylinder chambers of the cylinders being communicating with each other through a fluid path.

(34) To smoothly move the front and rear shutters 97F and 97R in the up-down direction, the weights of the front and rear shutters 97F and 97R are set to be substantially equal to each other. A rear face of the rear shutter 97R is provided with a handle 113 to move the front and rear shutters 97F and 97R up and down. After the front and rear shutters 97F and 97R are moved up and down, the endless member 105 is fixed to be immobile. For this, an end of the interlocking shaft 107 is provided with an electromagnetic brake 115 (refer to FIG. 8). A control switch 117 to turn on and off the electromagnetic brake 115 is arranged on the handle 113.

(35) When the handle 113 is held and the control switch 117 is operated to turn off the electromagnetic brake 115, the front and rear shutters 97F and 97R are movable up and down. When the control switch 117 is operated to turn on the electromagnetic brake 115, the front and rear shutters 97F and 97R are fixed to be immobile. In this way, the front and rear shutters 97F and 97R are moved up and down to keep the area above the front cover 95F or the rear cover 95R in an open state or a closed state.

(36) As is already understood, when the area above the front cover 95F is open, the area above the rear cover 95R is closed with the rear shutter 97R. In this case, the attaching, detaching, and changing of the punches P and dies D with respect to the tool support beams 83 of the frame 87 are carried out from the front side. On the other hand, when the area above the rear cover 95R is open and the area above the front cover 95F is closed with the shutter 97F, the attaching, detaching, and changing of the punches P and dies D with respect to the tool support beams 83 are carried out from the rear side.

(37) As mentioned above, when the front and rear shutters 97F and 97R are moved up and down, the rear shutter 97R closes, if moved up, the area above the rear cover 95R, and if moved down, opens the area. To detect the open and closed states, upper and lower open/close confirming sensors 119U and 119L (refer to FIG. 10) are arranged. The sensors 119U and 119L are, for example, limit switches and are arranged on the guide support 81L away from each other in the up-down direction. The rear shutter 97R is provided with a dog 121 to activate the sensors 119U and 119L.

(38) When the shutter 97R ascends and the dog 121 activates the sensor 119U, it is confirmed that the rear shutter 97R has ascended and the front shutter 97F has descended. Then, the tool changing apparatus 79 is able to attach, detach, and change the punches P and dies D. On the other hand, if the shutter 97R descends and the dog 121 activates the sensor 119L, it is confirmed that the rear shutter 97R has descended and the front shutter 97F has ascended. In this case, the tool changing apparatus 79 is unable to attach, detach, or change the punches P and dies D and it is possible to change the punches P and dies D from the rear side of the tool stocker 77. Accordingly, a configuration may be made to interlock the tool changing apparatus 79 when the upper sensor 119U is activated by the dog 121 and release the interlock when the lower sensor 119L is activated. This improves safety.

(39) The tool changing apparatus 79 is arranged in a left and right pair as illustrated in FIG. 5. Although it is preferable to arrange a pair of left and right tool changing apparatuses 79, it is not always necessary to arrange the tool changing apparatus 79 in a pair. It is possible to arrange only one tool changing apparatus 79. The pair of tool changing apparatuses 79L and 79R are left-right symmetrical with each other, and therefore, one of the tool changing apparatuses 79 will be explained. Structural elements of the other tool changing apparatus 79 are represented with like reference marks to omit overlapping explanations.

(40) The left and right tool changing apparatuses 79L and 79R have slide bases 125 that are individually movable in the left-right direction along guide rails 123 that extend in the left-right direction between the left and right side frames 3L and 3R. Each of the slide bases 125 has an actuator (not illustrated) such as a servomotor or a linear motor. The actuators are individually controlled to individually move and position the slide bases 125.

(41) Each of the slide bases 125 has a guide rail 125G extending in the front-rear direction. Each of the guide rails 125G has a slide support 127 that elongates in the up-down direction and is individually moved and positioned in the front-rear direction. The moving and positioning of the slide support 127 in the front-rear direction are carried out by individually controlling an actuator (not illustrated) provided for the slide support 127.

(42) Each of the slide supports 127 has an up/down support 129 that is movable in the up-down direction and is able to be positioned at a proper height. The up/down support 129 is moved up and down by an up/down actuator (not illustrated) made of a ball screw or the like turned by, for example, a fluid pressure cylinder or a servomotor. The up/down actuators are individually controlled to individually move the up/down supports 129 and position them at proper heights.

(43) As schematically illustrated in a plan view of FIG. 11, each of the up/down support 129 has a pivot 131 that horizontally turns around an axis extending in the up-down direction. An upper end of the pivot 131 is provided with a punch holding unit (tool holding unit) 133P to hold a punch P and a die holding unit (tool holding unit) 133D to hold a die D. The pivot 131 is also provided with a work contact member (back gauge) to position, in the front-rear direction, a work to be bent with the punch P and die D.

(44) As illustrated in FIG. 11, the punch holding unit 133P and die holding unit 133D, i.e., the tool holding units are arranged at positions deviated from the axis of the pivot 131. The punch holding unit 133P and die holding unit 133D are arranged at symmetrical positions with respect to the axis of the pivot 131. More precisely, the punch holding unit 133P and die holding unit 133D are deviated from the pivot 131 so that, when they are turned and positioned to face frontward (downward in FIG. 11) in the direction of the upper and lower tables 5 and 7, they can be brought into contact with each other in the left-right direction (X-axis direction).

(45) When split tools (punches P or died D) are taken out of the tool stocker 77 and are attached to the tool attaching units 9 and 13 of the upper and lower tables 5 and 7, the split tools taken by the left and right tool changing apparatuses 79L and 79R can be attached into a contacted state.

(46) Installed states of the punch holding unit 133P, die holding unit 133D, and back gauge (work contact member) 135 onto the pivot 131 are illustrated in detail in FIG. 12. The pivot 131 (not illustrated in FIG. 12) is horizontally rotatably installed in the up-down support 129. On a top face of the pivot 131, a pivot base 137 is integrally arranged. At symmetrical positions around a pivot center of the pivot base 137, the punch holding unit 133P and die holding unit 133D are arranged.

(47) The punch holding unit 133P and die holding unit 133D are constituted similar to the upper-tool changing apparatus 37U and lower-tool changing apparatus 37L of the related art mentioned above. The punch holding unit 133P and die holding unit 133D are formed to be up-down symmetrical. Accordingly, the structure of the punch holding unit 133P will be explained and like elements of the die holding unit 133D are represented with like reference marks to avoid overlapping explanations.

(48) Arranged on the pivot base 137 is a pedestal 139 protruding upward. The pedestal 139 has support wall members 141 that horizontally extend in opposite directions. One of the support wall members 141 is provided with the punch holding unit 133P. Namely, the support wall member 141 has a guide member 143 corresponding to the guide member 53 mentioned above. The guide member 143 movably supports a hook support member 145 corresponding to the hook support member 59 mentioned above. The hook support member 145 has a front end part 145A and projection part 145B corresponding to the front end part 59A and upward projection 59B mentioned above. As an actuator to move the hook support member 145 front and rear, a front-rear actuator 147 corresponding to the front-rear actuator 61 mentioned above is arranged on the pivot base 137.

(49) Arranged to reciprocate on a top face of the hook support member 145 is a hook attaching member 149 corresponding to the hook attaching member 63 mentioned above. The hook attaching member 149 has a hook member 151 that corresponds to the hook member 69 mentioned above and is pivotable up and down. The hook member 151 has an upward projection 151A. A front-rear actuator 153 corresponding to the front-rear actuator 65 mentioned above is arranged on the support wall member 141. The other support wall member 141 has the die holding unit 133D.

(50) Arranged on the pedestal 139 is the back gauge (work contact member) 135 that is swingable upward. Namely, arranged on the pedestal 139 is a U-shaped bracket 155. The bracket 155 has a horizontal pivot 157 that is orthogonal to the moving direction of the hook support member 145 of the punch holding unit 133P. The pivot 157 supports the back gauge 135 that is upwardly swingable from a horizontal state.

(51) To swing the back gauge 135 up and down, the bracket 155 has an L-shaped support bracket 159. The support bracket 159 has a fluid pressure cylinder 161 as an example of a swing actuator to swing the back gauge 135 up and down. The fluid pressure cylinder 161 has a reciprocable piston rod 161P whose front end is properly connected to the back gauge 135.

(52) With the above-mentioned configuration, the swing actuator 161 operates to swing the back gauge 135 upward from a horizontal state. When the die holding unit 133D attaches, detaches, or changes a die D, the die D never interferes with the back gauge 135.

(53) As is already understood, the punch holding unit 133P and die holding unit 133D of the left and right tool changing apparatuses 79L and 79R are moved and positioned in the left-right direction (X-axis direction), front-rear direction (Y-axis direction), and up-down direction (Z-axis direction), and in addition, are pivotable in the front-rear direction. Accordingly, the punch P and die D are able to be attached, detached, and changed between the tool stocker 77 and the tool attaching units 9 and 13 of the upper and lower tables 5 and 7.

(54) While the punch P and die D attached to the upper and lower tables 5 and 7 are bending a work, the inner side (front side) of the tool stocker 77 is closed with the front shutter 97F and the outer side (rear side) of the tool stocker 77 is opened as mentioned above. Accordingly, the punch P and die D are able to be attached, detached, and changed from behind the tool stocker 77.

(55) As mentioned above, a work to be bent is positioned in the front-rear direction by bringing the work into contact with the back gauge 135 provided for each of the left and right tool changing apparatuses 79L and 79R.

(56) When a work is bent with the punch P and die D, there is an occasion to bend the work after inverting the rear side of the punch P to front. To invert the rear side of the punch P to front, the embodiment employs a temporary tool holding unit 163 for temporarily holding the punch P. More precisely, as illustrated in FIG. 5, upper parts of the side frames 3L and 3R support left and right ends of a beam member 165 serving as a ceiling member. A bottom face of the beam member 165 is provided with the temporary tool holding unit 163.

(57) The temporary tool holding unit 163 is at an intermediate position in a moving path of the tool changing apparatuses 79L and 79R that move in the front-rear direction between the tool stocker 77 and the upper and lower tables 5 and 7 in the press brake 75. The temporary tool holding unit 163 has a tool holding beam 169 that is horizontally attached to lower ends of supports 167 that are vertically extended from the beam member 165. Formed in a bottom face of the tool holding beam 169 is a tool attaching groove 169G corresponding to the tool attaching groove 11. The pressing-fixing piece 31 is omitted from the tool attaching groove 169G.

(58) According to the above-mentioned configuration, the punch holding unit 133P of each of the tool changing apparatuses 79L and 79R removes a punch P from the tool stocker 77, transfers the same to the upper-tool attaching unit 9 of the upper table 5 in the press brake 75, and attaches the same thereto. At this time, the punch holding unit 133P is kept to be oriented rearward and the punch P is temporarily attached to the tool attaching groove 169G of the tool holding beam 169. Thereafter, the punch holding unit 133P is turned to face forward so as to hold, from the rear side, the punch P temporarily held in the tool attaching groove 169G. The punch holding unit 133P is kept to face forward and the punch P is attached to the upper-tool attaching unit 9 of the upper table 5. As a result, the punch P held in the tool stocker 77 is inverted to face forward and is attached to the upper table 5. Namely, the punch P is able to be attached to the upper table 5 after inverting the rear side of the punch P to front, or without inverting the same.

(59) As is understood from the above explanation, the embodiment is able to save space for the sheet material bending system as a whole and allows individual tools to be easily attached, detached, and changed with respect to the tool stocker 77 from the outside. In the above explanation, the tool stocker 77 is arranged between the left and right side frames 3L and 3R of the press brake 75. Instead, the tool stocker 77 may be arranged behind the left and right side frames 3L and 3R.

(60) FIG. 13 is a schematic plan view illustrating the second embodiment of the tool changing apparatuses 79L and 79R. The tool changing apparatuses 79LA and 79RA according to the second embodiment each integrate the punch holding unit 133P and die holding unit 133D into one. Namely, the second embodiment provides the pivot 131 with a back gauge 135 and an upper/lower-tool holding unit 171 that is able to handle both a punch (upper tool) P and a die (lower tool) D.

(61) When the upper/lower-tool holding unit 171 of this configuration holds a tool, i.e., a punch P or a die D, the tool and back gauge 135 must not interfere with each other. For this, the upper/lower-tool holding unit 171 and back gauge 135 are so arranged on the pivot 131 that front ends of the upper/lower-tool holding unit 171 and back gauge 135 face different directions, i.e., opposite directions. It is sufficient if the back gauge 135 does not interfere with the tool P or D when the upper/lower-tool holding unit 171 holds the tool P or D. Accordingly, the direction of the front end of the back gauge 135 is satisfactory if it differs from the direction of the front end of the upper/lower-tool holding unit 171.

(62) The upper/lower-tool holding unit 171 is structured as illustrated in FIGS. 14 and 15. Namely, a side face of a support wall member 141 integrally attached to the pivot 131 is provided with a hook support member 173 that is moved front and rear by a front-rear actuator 147. The hook support member 173 corresponds to the hook support member 145 mentioned above. An upward/downward projecting member 175 corresponding to the projection 145B mentioned above is integrally attached with a fixing member such as a bolt to a position close to a front end 173A of a long extended part 173L.

(63) The upward/downward projecting member 175 has an upward projection 175A that is positioned above the front end 173A and a downward projection 175B that is positioned below the same. A slant face 173S is formed on each of top and bottom faces of the front end 173A of the extended part 173L of the hook support member 173 in an area in front of the upward/downward projecting member 175. In the left and right tool changing apparatuses 79LA and 79RA, opposing faces 173F (refer to FIG. 16) of the front ends 173A of the hook support members 173 are formed into vertical faces. Side faces 173E opposite to the opposing faces 173F are formed into slant faces.

(64) Accordingly, the front ends 173A of the hook support members 173 are easily insertable into the through holes 29 of the tools P or D. In addition, when the tool is inserted into the through hole 29, this structure is able to reduce a clearance between the front end 173A and the through hole 29, thereby ensuring a position where the hook support member 173 holds the tool P or D. As a result, the tools P or D are brought into contact with each other in the left-right direction at correct positions.

(65) In the upper/lower-tool holding unit 171, a side face of the support wall member 141 is provided with a front-rear actuator 153 corresponding to the front-rear actuator 153 mentioned above. The front-rear actuator 153 moves a hook attaching member 177 front and rear. The hook attaching member 177 has a pivot 181 that supports a longitudinal intermediate part of an upper hook member (upper finger) 179 corresponding to the hook member 151. With the pivot 181, the upper hook member 179 is pivotable up and down. The hook attaching member 177 also has a pivot 185 that supports an intermediate part of a lower hook member (lower finger) 183 so that the lower hook member 183 may pivot up and down.

(66) The upper hook member 179 is arranged above the extended part 173L of the hook support member 173 and the lower hook member 183 is arranged below the extended part 173L. A front end of the upper hook member 179 has an upward projection 179A projecting upward and the lower hook member 183 has a downward projection 183A.

(67) A base end of each of the upper and lower hook members 179 and 183 has a spring seat 187. Arranged between the spring seats of the upper and lower hook members 179 and 183 is a resilient member 189 such as a coil spring to always bias the front ends of the hook members 179 and 183 toward each other. Accordingly, the pressing force of the resilient member 189 brings the front ends of the upper and lower hook members 179 and 183 into contact with each other in a normal state.

(68) In the upper/lower-tool holding unit 171, another side face of the front end of the support wall member 141 has a bracket 190 that supports an identification reading unit 191. The identification reading unit 191 reads an identifier such as a barcode on a tool P or D. When the tool stocker 77 stores a plurality of tools P and D, the identification reading unit 191 is positioned to a height of tools P and D supported by any one of the tool support beams 83 and the slide base 125 is moved in the X-axis direction so that the identification reading unit 191 reads identifiers of the tools P and D.

(69) A moving position of the slide base 125 in the X-axis direction is read by a position detecting unit (for example, a rotary encoder on a servomotor). A height of the tool support beam 83 is read by a height detecting unit (such as a rotary encoder provided for the servomotor for moving the up/down support 129 in the up-down direction). These detecting units detect a moving position in the X-axis direction of the upper/lower-tool holding unit 171 and an up-down moving position of the same. The X-axis and up-down positional data are related to the identification data of each tool P or D read by the identification reading unit 191 and the related data are stored in a memory of a control apparatus (not illustrated). The stored data enable the management of the plurality of tools P and D stored in the tool stocker 77.

(70) In the upper/lower-tool holding unit 171 illustrated in FIG. 17(A), the front end 173A of the hook support member 173 is moved to the front ends of the upper and lower hook members 179 and 183. In this state, the upper and lower hook members 179 and 183 are kept to be substantially parallel with each other. When the front end 173A of the hook support member 173 is retracted, the action of the resilient member 189 brings the front ends of the upper and lower hook members 179 and 183 closer to each other (refer to FIG. 17(B)).

(71) When the front ends of the upper and lower hook members 179 and 183 come close to each other as mentioned above, the front ends of the upper and lower hook members 179 and 183 are inserted into the through hole 29 of the tool P or D (refer to FIG. 17(B)). Thereafter, the front end 173A of the hook support member 173 is pushed between the front ends of the upper and lower hook members 179 and 183. Then, the upward/downward projecting member 175 of the hook support member 173 comes into contact with the tool P or D and the front ends of the upper and lower hook members 179 and 183 are separated from each other (refer to FIG. 18(A)).

(72) Thereafter, the front-rear actuator 153 is activated to move the upper and lower hook members 179 and 183 in a pull-out direction of the through hole 29. Then, one of the upper projection 179A and lower projection 183A of the upper and lower hook members 179 and 183 presses the push button 19B of the stop piece 19 of the tool P or D. As a result, the tool P or D is able to be released from the tool attaching groove 11 of a corresponding one of the upper- and lower-tool attaching units 9 and 13.

(73) As is already understood, the upper/lower tool holding unit 171 is able to handle upper and lower tools P and D. There is no need of separately preparing the punch holding unit 133P and die holding unit 133D, thereby simplifying the general structure of the system.

(74) FIG. 19 is an explanatory view illustrating a sheet material bending system according to the third embodiment of the present invention. The sheet material bending system according to this embodiment provides a general press brake having a back gauge 193, which is moved and positioned in the front-rear and left-right directions, with tool changing apparatuses 79LB and 79RB at lower part (on a bottom face) of a beam member 165 whose left and right sides are supported at upper part of left and right side frames 3L and 3R of the press brake.

(75) Namely, the tool changing apparatuses 79LB and 79RB have a pair of slide bases 197 that are arranged on guide rails 195 extending in the left-right direction on the bottom face of the beam member 165 and are moved and positioned in the left-right direction. The slide base 197 has a vertical slide support 199 that is moved and positioned in the front-rear direction. The slide support 199 has an up/down support 201 that is movable up and down. A lower end of the up/down support 201 has a pivot 203 that is horizontally rotatable and has the upper/lower tool holding unit 171 mentioned above.

(76) This structure corresponds to a structure with the tool changing apparatuses 79L and 79R turned upside down and arranged on the bottom face of the beam member 165. Accordingly, this structure is able to attach, detach, and change tools P and D between the tool stocker 77 arranged behind the press brake and the tool attaching units 9 and 13 of the upper and lower tables 5 and 7. This structure is easily realized by providing a general press brake with the beam member 165 and tool stocker 77 afterward.

(77) FIG. 20 illustrates another embodiment of the tool changing apparatuses 79LB and 79RB. The tool changing apparatuses 79LC and 79RC illustrated in FIG. 20 have each a tool holding unit 205 at a lower end of an up/down support 201, the tool holding unit 205 being capable of handling an upper tool and a lower tool. More precisely, the lower end of the up/down support 201 of each of the tool changing apparatuses 79LC and 79RC has a rotary actuator 207L (207R) such as a servomotor.

(78) Each of the rotary actuators 207L and 207R has a rotary shaft extending in the left-right direction. At each of facing ends of the rotary shafts, an L-shaped rotary bracket 209L (209R) is arranged. Each of the rotary brackets 209L and 209R has a rotary actuator 211L (211R (not illustrated)) having a rotary shaft that is orthogonal to the rotary shaft of the rotary actuator 207L (207R).

(79) The rotary shaft of each of the rotary actuators 211L and 211R is integrally provided with a rotary support member 213L (213R). Each of the rotary support members 213L and 213R is provided with the tool holding unit 205 that has the same structure as the punch holding unit 133P or the die holding unit 133D. Since the tool holding unit 205 has the same structure as the punch holding unit 133P or the die holding unit 133D, FIG. 20 schematically illustrates the tool holding unit 205 without details.

(80) In the above-mentioned configuration, the rotary actuator 207L (207R) turns the rotary bracket 209L (209R). Then, a front end of the rotary support member 213L (213R) supported by the rotary bracket 209L (209R) is able to be oriented toward the rear and a rear end thereof toward the front. If the rotary actuator 211L (211R) turns the rotary support member 213L (213R), the tool holding unit 205 provided for the rotary support member 213L (213R) is turned upside down.

(81) In this way, turning the tool holding unit 205 upside down results in switching the tool holding unit 205 between a state to deal with an upper tool (punch) P and a state to deal with a lower tool (die) D, thereby handling both the upper and lower tools P and D.

(82) The front end of the rotary support member 213L (213R) is oriented toward the rear to pick up a tool from the tool stocker 77, and thereafter, the rotary support member 213L (213R) is oriented to the front as illustrated in FIG. 20(A). This results in turning the picked-up tool P upside down. The rotary actuator 211L (211R) is driven to turn the rotary support member 213L (213R) upside down, so that the tool P is turned upside down to restore the original state (refer to FIG. 20(B)).

(83) As is already understood, holding the tool P as illustrated in FIG. 20(A) in the above-mentioned configuration enables the tool P to be attached to and detached from the lower table 7. Turning the tool P upside down as illustrated in FIG. 20(B) enables the tool P to be attached to and detached from the upper table 5. This configuration also eliminates the need of separately preparing the punch holding unit 133P and die holding unit 133D, thereby simplifying the system as a whole.

(84) In the above explanation, the tool changing apparatuses 79LC and 79RC are vertically hung from the beam member 165. It is also possible to configure the punch holding unit 133P illustrated in FIG. 11 so that it is able to be inverted front and rear and up and down like the tool holding unit 205 illustrated in FIG. 20, to eliminate the die holding unit 133D.

(85) The present invention is able to simplify the system as a whole and save space. When the tool changing apparatus is changing a tool with respect to the press brake, or when a work is being bent by the press brake, the present invention is able to manually change tools with respect to the tool stocker from behind the tool stocker. Accordingly, the present invention is able to improve the efficiency of tool preparation work.

UNITED STATES DESIGNATION

(86) In connection with United States designation, this international patent application claims the benefit of priority under 35 U.S.C. 119(a) to Japanese Patent Application No. 2012-231422 filed on Oct. 19, 2012 whose disclosed contents are cited herein.