Abstract:
A forming apparatus to bend a plate-shaped material, including: a first forming device to bend one surface of the plate-shaped material not more than 180 degrees by pressing the plate-shaped material; a second forming device to bend another surface of the plate-shaped material not more than 180 degrees by pressing the plate-shaped material; wherein the first and the second forming device perform bending while changing a relative position by interlocking with each other.

Description:
This application is based on Japanese Patent Application No. 2009-110697 filed on Apr. 30, 2009, in Japanese Patent Office, the entire content of which is hereby incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     The present invention relates to a forming apparatus to form a part in a shape of a plate such as a metal and a forming method the same. 
     TECHNICAL FIELD 
     As a parts which is formed by bending a plate-like part at a plurality of positions, for examples, there are parts in a shape of W character which is formed by bending a metal plate in a W character shape shown in  FIG. 23 , and a part provided with a projection section at a portion of a metal plate which bended in a L character shape shown in  FIG. 23(   b ). The above parts are used for various structures, since bending strength against an external force can be increased compared to a piece of simple plate material. 
     Conventionally, as a method to form a W-shape parts form a plate-shaped material, there has been a method to form the W-shape part from the plate-shaped part via a plurality of processes. Also, there has been a forming method to form the part with the projection section by drawing. 
     As the method to form the W-shape part via a plurality of the processes, for example, there have been known a method that the plate-shaped material is formed in a shape of a V character with a pair of a punch and a die in the V-shape, then the plate-shaped material is displaced so as to form another V-shape next to the V-shape to obtain the W-shape part and a method that a pair of a punch and a die in W-shape performs drawing work with respect to the plate-shaped material to obtain the W-shape part. 
     Also, as a method to form the aforesaid part having the projection section, there has been known a method that a plate-shaped material, on which slits are punched intermittently at a position supposed to be a ridge line of the projection section, is bent at the ridge line by pushing the part to be a projection section so as to protrude the position to be a projection section (for example, Patent Document 1: Unexamined Japanese Patent Application Publication No. H4-33723) 
     Patent Document 1: Unexamined Japanese Patent Application Publication No. H4-33723 
     SUMMARY 
     However, there have been problems that the aforesaid methods via the plurality of the processes require a long working time and productivity is deteriorated, also safeness of the work is deteriorated by injuries when the material is moved manually. 
     Also, in the drawing work, there have been problems that since the material is extended, a thin section is created and the strength is deteriorated, in addition ensuring of accuracy is difficult. 
     Also, in the forming method described in the Patent Document 1, the projection section can be formed unfailingly in one process, however there is problem that since the portion where the slits are punched intermittently on the ridge line of the projection portion is weak in the bending resistance, there is a possibility that the mechanical strength against the external force is deteriorated. 
     An aspect of the present invention is to provide a forming apparatus and a forming method which enable manufacturing a large amount of the steel plate part formed by bending the plate-shaped material having a high mechanical strength, and ensuring required accuracy, with less occurrence of scratches while working, in a unit time. 
     The above object is achieved by the following. 
     1. A forming apparatus to bend a plate-shaped material, including: a first forming device to bend one surface of the plate-shaped material not more than 180 degrees by pressing the plate-shaped material; a second forming device to bend another surface of the plate-shaped material not more than 180 degrees by pressing the plate-shaped material; wherein the first and the second forming devices perform bending while changing a relative position by interlocking with each other. 
     2. A forming method of a plate-shaped part using a forming apparatus, to bend a plate-shaped material, includes: bending one surface of the plate-shaped material not more that 180 degrees by pressing the plate-shaped material by a first forming device; and bending an other surface of the plate-shaped material not more than 180 degrees by pressing the plate-shaped material by a second forming device while changing relative position with respect to the first forming device in accordance with progress of forming so as to coordinate with the first forming device. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an explanatory diagram of a first example of a bending apparatus which bends a plate-shaped material W by biasing a punch P and a die D by a motor. 
         FIG. 2  is an explanatory diagram of a first example of a bending apparatus which bends a plate-shaped material W by biasing a punch P and a die D by a motor. 
         FIG. 3  is a perspective view of a part which is formed by bending a plate-shaped material such as steel in a Z-shape by the bending apparatus  1 . 
         FIG. 4  is an explanatory diagram of an example of moving device  10 . 
         FIG. 5  is an explanatory diagram of a second example of a bending apparatus which bends a plate-shaped material W by biasing a punch P and a die D by a motor. 
         FIG. 6  is an explanatory diagram of a second example of a bending apparatus which bends a plate-shaped material W by biasing a punch P and a die D by a motor. 
         FIG. 7  is a perspective view of a part which is formed by bending the plate-shaped material at more than two positions through the bending apparatus  2 . 
         FIG. 8  is an explanatory diagram of a third example of a bending apparatus to carry out different bending works in a back side and a front side in a x direction of the plate-shaped material W by biasing a punch P and a died through a motor. 
         FIG. 9  is an explanatory diagram of a third example of a bending apparatus to carry out different bending works in a back side and a front side in a x direction of the plate-shaped material W by biasing a punch P and a died through a motor. 
         FIG. 10  is a perspective view of a part having been subject to different bending works in a back side and a front side with respect to a X direction representing a third direction which is perpendicular to both a first direction (t direction) and a second direction (y direction) which is perpendicular to the t direction. 
         FIG. 11  is an explanatory diagram of a fourth example of a bending apparatus to carry out different bending works in a back side and a front side in a x direction of the plate-shaped material W by biasing a punch P and a died through a motor. 
         FIG. 12  is an explanatory diagram of a fourth example of a bending apparatus to carry out different bending works in a back side and a front side in a x direction of the plate-shaped material W by biasing a punch P and a died through a motor. 
         FIG. 13  is a perspective view of a part having been subject to different bending works in a back side and a front side with respect to a x direction representing a third direction which is perpendicular to both a first direction (t direction) and a second direction (y direction) which is perpendicular to the t direction. 
         FIG. 14  is an explanatory diagram of a fifth example of a bending apparatus which bends a plate-shaped material W by biasing a punch P and a die D via a link mechanism. 
         FIG. 15  is an explanatory diagram of a fifth example of a bending apparatus which bends a plate-shaped material W by biasing a punch P and a die D via a link mechanism. 
         FIG. 16  is a perspective view of a part having been subject to bending work by pressing a plate-shaped material W by a bending apparatus  5 . 
         FIG. 17  is an explanatory view of sixth example of bending apparatus to perform bending of a plate-shaped material W by biasing a punch and a die via a link mechanism. 
         FIG. 18  is an explanatory view of sixth example of bending apparatus to perform bending of a plate-shaped material W by biasing a punch and a die via a link mechanism. 
         FIG. 19  is an explanatory view of sixth example of bending apparatus to perform bending of a plate-shaped material W by biasing a punch and a die via a link mechanism. 
         FIG. 20  is a perspective view of a part which has been formed by bending a plate-shaped material W in different woks in aback side and a front side in a x direction through a bending apparatus  6 . 
         FIG. 21  is an explanatory view of a seventh example of a part which is formed by bending a plate-shaped material W. 
         FIG. 22  is an external view of a plate-shaped material Won which slits are formed in advance. 
         FIG. 23(   a ) and  FIG. 23(   b ) are examples of parts which are formed by bending plate-shaped materials such as metal at a plurality of positions. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     A forming apparatus and a forming method to process a plate-shaped material such as metal will be described with reference to the drawings. Since the present invention focuses on bending the plate-shaped material, bending of plate-shaped material such as metal will be described. 
     Incidentally, a direction to push the plate-shaped material is called a first direction and a ridge line created on the plate-shaped material as a result of bending work by pushing is called a third direction and a direction perpendicular to the aforesaid two directions is called a second direction. 
     Meanwhile, in the following figures, the first direction is a thickness direction (t direction in figure), the second direction is a longitudinal direction perpendicular to the thickness direction of the plate-shaped material, for example, a height direction of the bending apparatus (y direction in the figure) and the third direction is a lateral direction perpendicular to both the thickness direction and the longitudinal direction of the plate-shaped material, for example a depth direction (x direction in the figure) of the bending apparatus. 
     The descriptions of “perpendicular” and “parallel” are ideally perpendicular and parallel, however, practically, they are substantially perpendicular and parallel, which allow tolerances of for example, ±1 degree. 
     The plate-shaped material such as metal is simply called as the plate-shaped material, the apparatus performs bending work with respect to the plate-shaped material is called bending apparatus. 
       FIG. 1  and  FIG. 2  are explanatory diagrams of a first example of the bending apparatus which bends the plate-shaped material W by biasing the punch P and the Die D via a motor, and  FIG. 3  is a perspective view of a part formed in a Z-shape by bending the plate-shaped material W such as metal with the bending apparatus  1 . 
     Specifically,  FIG. 1  shows a time point where the plate-shaped material W such as metal is set in the bending apparatus  1 , and  FIG. 2  shows a time point when bending work of the plate-shaped material such as metal is completed. 
     In  FIG. 1  and  FIG. 2 , the bending apparatus  1  is provided with a plurality of punch units PU which bend the plate-shaped material by the punch P and the die D by pressing (for example, a punch unit PU 1  representing a first forming device and a punch unit PU 2  representing a second forming device). A single punch unit PU 1  and a single punch unit PU 2  are disposed in a y direction alongside. 
     Here, a plurality of the punch units PU (for example, the punch unit PU 1  and the punch unit PU 2 ) disposed in a different position with respect to the y direction are disposed so that the bending directions are opposed in a positional relation of the punch P and die D with respect to a surface of the plate-shaped material W. For example, the punch unit PU 1  has a punch P 1  at a side W 1  and the die D 1  at a side W 2  and contrarily the punch unit PU 2  has the die D 2  at the side W 1  and a punch P 2  at the side W 2  so that bending directions by the adjacent punch units with respect to the plate-shaped material are opposite. 
     Namely, the punch unit PU 1  representing a first forming device bends a surface of the plate-shaped material W not more than 180 degree by pressing the plate-shaped material W, and the punch unit PU 2  representing the second forming device bends the other surface of the plate-shaped not more than 180° by pressing the plate-shaped material W. 
     A moving device  1001  to enable moving of the punch P 1  in the y direction and the t direction simultaneously is connected with the punch P 1  of the punch unit PU 1  and a moving device  1002  to enable moving of the die D 1  in the y direction and the t direction simultaneously is connected with the die D 1 . Further a moving device  1003  to enable moving of the die punch P 2  in the y direction and the t direction simultaneously is connected with the punch P 2  of the punch unit PU 2  and a moving device  1004  to enable moving of the die D 2  in the y direction and the t direction simultaneously is connected with the die D 2 . 
     Incidentally lengths of the punches P 1  and P 2 , dies D 1  and D 2  in the x direction is at least the same as the width of the plate-shaped material W or is not less that the width of the plate-shaped material. 
     Forming work will be described. An unillustrated control device controls a plurality of moving device so that, for example, moving devices  1001  and  1002 , and  1003  and  1004  coordinate with each other. 
     Here, coordinate means that bending angles θ (for example θ 1  and θ 2 ) created by two planes (for example, plane w 1  and w 2  and w 2  and w 3 ) which sandwiches a ridge r (for example, ridge r 1  and r 2 ) of each bending section O of plate-shaped material W bent by a plurality of pair of punches P and dies D (for example, punch P 1  and die D 1 , and punch P 2  and die D 2 ) coincide during bending, and the plate-shaped material W (for example, surface w 2 ) located between the punch unit PU 1  and the adjacent punch unit PU 2  disposed in the y direction always maintains a flat surface (a straight line in the figure) during bending, further the punch P 1 , the die D 1 , the punch P 2  and the die D 2  are coordinated and moved in the t and y directions so that the surfaces (for example surface w 1  and w 3 ) of plate-shaped material W become parallel each other when bending is completed, or extended surfaces of the aforesaid surfaces are always parallel during bending. 
     As described above, bending is carried out by moving and coordinating the punch P 1 , the die D 1 , the punch P 2  and the die D 2  relatively in the t and y directions to bend a plurality of positions, namely bending of the plurality of positions is carried out in one process, thus the productivity is enhanced without the material being extended such as in drawing work, and deterioration of strength of the completed part is avoided. 
     Here, during bending means starting of deformation by pushing the plate-shaped material W to completion of bending where the punch and the die substantially contact via the plate-shaped material W. 
     By forming tip sections of the punches P 1  and P 2  into projection sections in triangle shapes having angles less than 180° and forming the tip sections of the dies D 1  and D 2  into recessed sections in triangle shapes having an angle less than 180°, a bending press part having a discretionary bending angle θ can be formed. 
     Also, by forming the tip sections of the punches P 1  and P 2  into projection sections in triangle shapes having angles less than 90° and forming the tip section of the dies D 1  and D 2  into the recessed sections in triangle shapes having an angle less than 90°, a bending press part A 1  having bending angle θ of 90° shown in  FIG. 3  can be formed. 
     Also, it is preferable that all the tip sections of the punches P (projection section in the triangle shape) have the same shape and all the tip sections of the dies D (recessed section in triangle shape) have the same shape. In this ease, control can be simplified, by starting of movement the punches P and dies D at the same time with the same moving speed. 
     By utilizing the configuration described above, the bending angles θ of two bending positions can coincide during all bending work by the two pair of the punching units, and the plate-shaped material located between the two pair of punch units can always maintain the plane surface (the straight line in the figure) during bending work. Thus, bending work for two positions can be carried out in one process and production volume in a unit time can be increased, also the bending press parts can be safely produced since the plate-shaped material does not have to be replaced. Further, the plate-shaped material can be formed without slippage between the punch and the die. Whereby, there can be provided a bending apparatus for the plate-shaped material which enables production of a bending press part having a high mechanical strength, while maintaining a required accuracy with less occurrence of flaws during press work. 
       FIG. 4  is a detailed explanatory diagram of an example of a moving device  10 . 
     All the punches and dies of bending apparatus to bend plate-shaped material W by biasing the punch P and die D via a motor are connected to the following moving device. All the punches and dies are configured to be movable simultaneously in the t and y directions through the moving device. An example of the moving device will be described with punch P as an example. Incidentally, the moving device is not limited to the following configuration and any configurations enabling the punch P and die D to move in the t and y directions are possible. 
     First, moving of punch P (die D) in the t direction will be described. 
     The punch P is fixed on the punch support shaft  101  to support the punch. The punch supporting shaft  101  is supported by a guide member  102  in a sliding manner in the t direction. The punch support shaft  101  has a cam follower  103  and the can follower  103  is fitted with a cam groove  105  formed on a cam plate  104  which moves the punch P in the t direction. 
     As the figure shows, the cam plate  104  provided with the cam groove  105  inclining in the t direction and a female screw  106 , is movable in the y direction while being guided by the guide plate  107 . The female screw  106  is engaged with a male screw  108  disposed at a motor output shaft of the motor Mt to move the punch P in the t direction. 
     The male screw  108  rotates by rotation of the motor Mt and the cam plate  104  moves in the y direction via the female screw  106 . By the above movement, the punch support shaft  101 , namely the punch P moves in the t direction via the cam follower  103  and the cam groove  105 . 
     Incidentally, the guide member  102  is fixed integrally with a block  109  which moves the guide member  102  in the y direction and the guide plate  107 , and the motor Mt which move the punch P in the t direction are fixed on the block  109 . With the above configuration, by rotation of the motor Mt, the punch P can be moved in the t direction via cam plate  104 , the cam follower  103  and the punch support shaft  101 . 
     Next, moving of punch P in they direction will be described. 
     A block  109  is supported by a guide member  110  fixed on a base  1   a  in a sliding manner in the y direction. The block  109 , having a female screw  112  engaging with a male screw  111  disposed on a motor output shaft of a motor My which moves the block  109  in the y direction, can be moved in the y direction being guided by the guide member  110 . Then the male screw  111  rotates by rotation of the motor My fixed on the base  1   a  and the block  109  moves in the y direction via the female screw  112 , and the punch P moves in the y direction via the guide member  101  by the above movement. 
     Here, the motor Mt represents a drive source to move the punch in a first direction (t direction) and represents a drive source to move the die in a first direction (t direction). The motor My represents a drive source to move the punch in a second direction (y direction) and represents a drive source to move the die in the second direction (y direction). 
     Also, the above guide member  102  to the male screw  111  to move the punch P integrally represents a punch moving section, and the above guide member  102  to the male screw  111  to move the die D integrally represents a die moving section. 
     Incidentally, the motor Mt and motor My are connected with a control device (unillustrated), and movement of the punch and die in the t and y directions are controlled by the control device. For example, if the motor Mt and motor My are driven to rotate at the same time by the control device, the punch or die can be moved in both the t and y directions at the same time. 
     A pulse motor or a servo motor can be used for the motor Mt and the motor My to precisely position the punch and the die. In order to obtain large biasing force and highly precise amount of rotations, a hydraulic pulse motor may be used. 
     In case the pulse motor is used for the motor Mt and the motor My, a measurement of displacement amount of the punch and the die in y-direction and t-direction can be realized by calculating the drive pulse of the motor Mt and the motor My and converting the number of pulses into the displacement amount. In case the servo motor is used for the motor Mt and the motor My, the measurement of displacement amount of the punch and the die in y-direction and t-direction can be realized by calculating the pulse of a pulse encoder provided at an output shaft of the motor Mt and motor My and converting the number of pulses into the displacement amount 
     An actual position of the punch and the die in the t-direction can be detected by calculating each pulse after a starting point sensor (not illustrated), which outputs a starting point signal at the time when the leading edges of the punch and the die that have been separated from a plate-shaped material W come into contact with the plate-shaped material W, sends out an output. An actual position of the punch and the die in the y-direction can be detected by calculating each pulse after a lower limit sensor (not illustrated), which detects the lower limit position in the y-direction, detects the lower limit. 
     The value of the bending angle, which is formed by two surfaces that sandwich a ridge of each bending section of the plate-shaped material bent by a plurality of pairs the punch P and the die D, is maintained the same during the bending process. Also the surfaces of the plate-shaped material or the extended surface of those surfaces that become parallel to each other at the time of completion of the bending process are maintained to be parallel to each other at all times during the bending process. Required moving amount information of the punch and the die in the t-direction and the y-direction for prescribed period of time that is needed for the plate-shaped material disposed between the adjacent punch units to maintain a fair surface during the bending process is memorized in a memory device (not illustrated) in advance. 
     With respect to a processing method, a control device compares the calculated number of pulses of the motor Mt and the motor My during the bending processing with the memorized required moving amount information of the punch and the die in the t-direction and the y-direction for a prescribed period of time during the bending processing. Then the control device controls the motor Mt and the motor My so that the calculated number of pulses and the memorized required moving amount information coincide. 
     By configuring a bending apparatus with the above described configuration, the value of the bending angle, which is formed by two surfaces that sandwich a ridge of each bending section of the plate-shaped material bent by a plurality of pairs of the punch P and the die D, is maintained the same during the bending process. Also the surfaces of the plate-shaped material or the extended surface of those surfaces that become parallel to each other at the time of completion of the bending process are maintained to be parallel to each other at all times during the bending process. As a result, the plate-shaped material disposed between the adjacent punch units always maintains a fair surface during the bending process. 
       FIGS. 5 and 6  illustrate explanatory diagrams of a second example of a bending apparatus for bending the plate-shaped material W by energizing a punch P and a die D with a motor.  FIG. 7  illustrates a perspective view of a part onto which a bending process has been performed on not less than two sections of the plate-shaped material W by a bending apparatus  2 . 
     In detail,  FIG. 5  illustrates a time when the plate-shaped material W has been set in the bending apparatus  2 , and  FIG. 6  illustrates a time when the bending process to the plate-shaped material W has completed. 
     The bending apparatus  2  includes a plurality of punch units PU (for example, punch unit PU 3 -punch unit PU 6 ), which bends the plate-shaped material W by pressing the plate-shaped material W with a punch P and a die D. The punch unit PU 3 -punch unit PU 6  are disposed collaterally along the y-direction. 
     Here, the plurality of punch units (for example, punch unit PU 3 -punch unit PU 6 ) is disposed at different positions with respect to y-direction. With respect to the spatial relationship of the punch P and the die D against the surface of the plate-shaped material W, the plurality of punch units is arranged so that the bending direction to the plate-shaped material W is opposite of that of an adjacent punch unit. 
     For example, with respect to the punch unit PU 3  in which punch P 3  is disposed on a surface W 1  side and die D 3  is disposed on a surface W 2  side, the punch unit PU 4  is arranged so that die D 4  is disposed on the surface W 1  side and punch P 4  is disposed on the surface W 2  side. Also, with respect to the punch unit PU 4  in which the die D 4  is disposed on the surface W 1  side and the punch P 4  is disposed on the surface W 2  side, the punch unit PU 5  is arranged so that punch P 5  is disposed on the surface W 1  side and die D 5  is disposed on the surface W 2  side. Also, with respect to the punch unit PU 5  in which the punch P 5  is disposed on the surface W 1  side and the die D 5  is disposed on the surface W 2  side, the punch unit PU 6  is arranged so that die D 6  is disposed on the surface W 1  side and the punch PG is disposed on the surface W 2  side. The plurality of punch units is arranged in this manner so that the bending direction to the plate-shaped material is the opposite of the adjacent punch unit. 
     That is, the punch units PU 3  and PU 5  bend one surface of the plate-shaped material W to not more than 180 degrees by pressing the plate-shaped material W. Then the punch units PU 4  and PU 6  bend the other surface of the plate-shaped material W to not more than 180 degrees by pressing the plate-shaped material W. 
     A moving device  1005 , which enables the punch P 3  to move in y-direction and t-direction simultaneously, is connected to the punch P 3  of the punch unit PU 3 . A moving device  1006 , which enables the die D 3  to move in y-direction and t-direction simultaneously, is connected to the die D 3  of the punch unit PU 3 . A moving device  1007 , which enables the punch P 4  to move in y-direction and t-direction simultaneously, is connected to the punch P 4  of the punch unit PU 4 . A moving device  1008 , which enables the die D 4  to move in y-direction and t-direction simultaneously, is connected to the die D 4  of the punch unit PU 4 . 
     In the similar manner, moving devices  1009  and  1010 , which enable the punch P 5  and the die D 5  to move in y-direction and t-direction simultaneously, are connected to punch P 5  and the die D 5  of the punch unit PU 5 , respectively. Moving devices  1011  and  1012 , which enable the punch P 6  and the die D 6  to move in y-direction and t-direction simultaneously, are connected to punch P 6  and the die D 6  of the punch unit PU 6 . 
     Punches P 3 -P 6  and dies D 3 - 6  have the length that is the same as or more than the width of the plate-shaped material W in the x-direction. 
     With regards to the description of a processing method, a non-illustrated control device controls a plurality of moving devices, for example, the moving devices  1005 - 1012 , so that the plurality of moving devices moves in response to each other. 
     The value of the bending angle θ (for example, θ 3 -θ 6 ), which is formed by two surfaces (for example, surfaces w 4  and w 5 , surfaces w 5  and w 6 , surfaces w 6  and w 7  and surfaces w 7  and w 8 ), that sandwich a ridge (for example, ridges r 3 -r 6 ) being a bent section O bent by the punch P and the die D (for example, the punch P 3  and the die D 3 , the punch P 4  and the die D 4 , the punch P 5  and the die D 5  and the punch P 6  and the die D 6 ), is maintained the same during the bending process. Also the surfaces (for example, surfaces w 4 , w 6  and w 8  and surfaces w 5  and w 7 ) of the plate-shaped material or the extended surface of those surfaces that become parallel to each other at the time of completion of the bending process are maintained to be parallel to each other at all times during the bending process. Moving in response to each other refers to controlling and moving the punch P 3 , the die D 3 , the punch P 4 , the die D 4 , the punch P 5 , the die D 5 , the punch P 6  and the die D 6  in response to each other so that the plate-shaped material W (for example, surfaces w 5 -w 7 ), which is arranged between the punch unit PU 3  and the punch unit PU 4 , the punch unit PU 4  and the punch unit PU 5  and the punch unit PU 5  and the punch unit PU 6  disposed adjacent to each other in the y-direction, maintains a fair surface (straight line in the figure) during the bending process. 
     As described above, a bending process is performed to a plurality of places on the plate-shaped material by moving the punch P 3  and die D 3 -the punch P 6  and die D 6  in response to each other and relatively moving the punch P 3  and die D 3 -the punch P 6  and die D 6  to the t-direction and y-direction, respectively. That is, a bending process to a plurality of places can be performed in one process. Therefore, productivity can be improved, and reduction of strength of the completed parts can be prevented without stretching the material just as in a drawing process. 
     A bent sheet metal part having an arbitrary bending angle θ can be processed by arranging a leading edge section of the punch P 3 -punch P 6  with a triangle-shaped convex section having less than 180 degree angle on a leading edge section and by arranging a leading edge section of the die D 3 -die D 6  with a triangle-shaped concave section having less than 180 degree angle on the trough just as in the punch P 3 -punch P 6 . 
     A bent sheet metal A 2  having 90 degrees of a bending angle θ as illustrated in  FIG. 7  can be processed by arranging a leading edge section of the punch P 3 -punch P 6  with a triangle-shaped convex section having 90 degree angle on a leading edge section and by arranging the leading edges of the die D 3 -die D 6  with a triangle-shaped concave section having 90 degree angle on the trough just as in the punch P 3 -punch P 6 . 
     It is desirable that the shape of the leading edge section (triangle-shaped convex section) of all the punches P is the same, and the shape of the leading edge section (triangle-shaped concave section) of all the die D is the same. In this case, starting time of the movement of all the punches P and dies D is set to the same time, and speed of the movement of all the punches P and dies D can be set to the same speed. Thus, the control can be simplified. 
     A case in which the bending process was performed to four places of the plate-shaped material W has been described above. However, it is needless to mention that the bending process can be performed to arbitrary numbers of places on the plate-shaped material by disposing a number of punch units PU in the y-direction. Also it is needless to mention that the interval of each punch unit in the y-direction may be the same or may differ. 
     By configuring the bending apparatus  2  with the configuration described above, the bending angle θ of the four bending sections is maintained to an equal value at all times during the bending process by each of the moving devices of four pairs of the punch unit. Also, surfaces or extended surfaces of the plate-shaped material W, which become mutually parallel at the time of completion of the bending process, are held parallel at all times during the bending process. Hence, the plate-shaped material placed between the four pairs of punch unit can maintain a fair surface (straight line in the illustration) at all times during the bending process. 
     Thereby, the bending of four places can be performed in one process. Thus, there is no need to replace the plate-shaped material. The bent sheet metal part can be safely produced while increasing the amount of production per unit of time. 
     Also the plate-shaped material is processed without sliding between the punch and the die. Therefore, a plate-shaped material bending apparatus with high mechanical intensity that can produce a high quality bent sheet metal without scratches. 
     A bending apparatus that is capable of bending the near side and far side in x-direction of the plate-shaped material W differently will be described hereafter. 
       FIGS. 8 and 9  illustrate explanatory diagrams of a third example of a bending apparatus for performing bending processing to the near side and the far side in x-direction of the plate-shaped material W differently by energizing the punch P and the die D with the motor.  FIG. 10  illustrates a perspective view of a part onto which a different bending process has been performed to the near side and the far side in x-direction of the plate-shaped material being a third direction which is perpendicular to a first-direction (t-direction) and a second direction (y-direction), which is perpendicular to the t-direction. 
     In detail,  FIG. 8  illustrates a time when the plate-shaped material W is set to the bending apparatus  3 .  FIG. 9  illustrates a time when the bending process to the plate-shaped material W has been completed. 
     “x 1 ” of  FIG. 10  indicates a bending area of the near side in x-direction of the plate-shaped material W. “x 2 ” of  FIG. 10  indicates a bending area of the far side in x-direction of the plate-shaped material W. 
     The bending apparatus  3  includes a plurality of a first processing device and a plurality of a second processing device whose number of processing device is one less than that of the first processing device on the near side (bending area x 1 ). The bending apparatus  3  includes at least two first processing devices and at least one second processing device on the far side (bending area x 2 ). 
     In  FIGS. 8 and 9 , the bending apparatus  3  includes a plurality of punch units PU (for example, punch unit PU 7 -punch unit PU 14 ) for bending the plate-shaped material W by pressing the plate-shaped material W with punch P and die D. Punch units PU 12 , PU 13  and PU 14  are disposed on the far side (bending area x 2 ) in the x-direction of the plate-shaped material W and disposed at different positions in y-direction. Punch units PU 7 , PU 8 , PU 9 , PU 10  and PU 11  are disposed on the near side (bending area x 1 ) in the x-direction of the plate-shaped material W and disposed at different positions in y-direction. 
     A plurality of punch units PU (for example, punch unit PU 7 -punch unit PU 11  and punch unit PU 12 -punch unit PU 14 ), which is disposed in the bending area x 1  and bending area x 2  in the y-direction, is arranged so that the bending direction of punch P and die D of each punch unit to the surface of the plate-shaped material W becomes opposite of each other. 
     In the bending area x 1 , the plurality of punch units is arranged so that the bending direction of the punch unit against the plate-shaped material W is opposite of that of the adjacent punch unit. For example, in the bending area x 1 , the die D 8  and the punch P 8  of the punch unit PU 8  are disposed on the surface W 1  side and on the surface W 2  side, respectively, in respect to the punch P 7  and the die D 7  of the punch unit PU 7 , which are disposed on the surface W 1  side and on the surface W 2  side, respectively. Also, the punch P 9  and the die D 9  of the punch unit PU 9  are disposed on the surface W 1  side and on the surface W 2  side, respectively, in respect to the die D 8  and the punch P 8  of the punch unit PU 8 , which are disposed on the surface W 1  side and on the surface W 2  side, respectively. Also, the die D 10  and the punch P 10  of the punch unit PU 10  are disposed on the surface W 1  side and on the surface W 2  side, respectively, in respect to the punch P 9  and the die D 9  of the punch unit PU 9 , which are disposed on the surface W 1  side and on the surface W 2  side, respectively. And in the similar manner, the punch P 11  and the die D 11  of the punch unit PU 11  are disposed on the surface W 1  side and on the surface W 2  side, respectively, in respect to the die D 10  and the punch P 10  of the punch unit PU 10 , which are disposed on the surface W 1  side and on the surface W 2  side, respectively. In the bending area x 2 , the die D 13  and the punch P 13  of the punch unit PU 13  are disposed on the surface W 1  side and on the surface W 2  side, respectively, in respect to the punch P 12  and the die D 12  of the punch unit PU 12 , which are disposed on the surface W 1  side and on the surface W 2  side, respectively. Also, the punch P 14  and the die D 14  of the punch unit PU 14  are disposed on the surface W 1  side and on the surface W 2  side, respectively, in respect to the die D 13  and the punch P 13  of the punch unit PU 13 , which are disposed on the surface W 1  side and on the surface W 2  side, respectively. 
     That is, the punch units PU 12 , PU 7 , PU 9 , PU 11  and PU 14  being the first processing devices are capable of bending one surface of the plate-shaped material W to not more than 180 degrees by pressing the plate-shaped material W. The punch units PU 8 , PU 13  and PU 10  being the second processing device are capable of bending the other surface of the plate-shaped material W to not more than 180 degrees by pressing the plate-shaped material W. 
     With the configuration described above, the bending area x 1  and the bending area x 2  of the plate-shaped material W are bent so that the bending direction of each of the bending area opposes each other. 
     A moving device  1023 , which enables the punch P 12  to move in the y-direction and the t-direction simultaneously, is connected to the punch P 12  of the punch unit PU 12 . A moving device  1024 , which enables the die D 12  to move in the y-direction and the t-direction simultaneously, is connected to the die D 12  of the punch unit PU 12 . Moving devices  1025  and  1026 , which enable the punch P 13  and the die D 13  to move in the y-direction and the t-direction simultaneously, are connected to the punch P 13  and the die D 13  of the punch unit PU 13 . In the same manner, moving devices  1027  and  1028 , which enable the punch P 14  and the die D 14  to move in the y-direction and the t-direction simultaneously, are connected to the punch P 14  and the die D 14  of the punch unit PU 14 . 
     A moving device  1013 , which enables the punch P 7  to move in the y-direction and the t-direction simultaneously, is connected to the punch P 7  of the punch unit PU 7 . A moving device  1014 , which enables the die D 7  to move in the y-direction and the t-direction simultaneously, is connected to the die D 7  of the punch unit PU 7 . In the similar manner, moving devices  1015  and  1016 , which enable the punch P 8  and the die D 8  to move in the y-direction and the t-direction simultaneously, are connected to the punch P 8  and the die D 8  of the punch unit PU 8 . Moving devices  1017  and  1018 , which enable the punch P 9  and the die D 9  to move in the y-direction and the t-direction simultaneously, are connected to the punch P 9  and the die D 9  of the punch unit PU 9 . Moving devices  1019  and  1020 , which enable the punch P 10  and the die D 10  to move in the y-direction and the t-direction simultaneously, are connected to the punch P 10  and the die D 10  of the punch unit PU 10 . Moving devices  1021  and  1022 , which enable the punch P 11  and the die D 11  to move in the y-direction and the t-direction simultaneously, are connected to the punch P 11  and the die D 11  of the punch unit PU 11 . 
     The punches P 7 , P 8 , P 9 , P 10  and P 11  and the dies D 7 , D 8 , D 9 , D 10  and D 11  disposed on the near side have the length that is the same as the width of the bending area x 1  in x-direction or the length that is not less than the width of the bending area x 1  in x-direction. The punches P 12 , P 13  and P 14  and the dies D 12 , D 13  and D 14  disposed on the far side have the length that is the same as the width of the bending area x 2  in x-direction or the length that is not less than the width of the bending area x 2  in x-direction. 
     The far side edges (not illustrated) of the punches P 7 , P 8 , P 9 , P 10  and P 11  and the dies D 7 , D 8 , D 9 , D 10  and D 11  disposed on the near side come slidably in contact with the near side edges (not illustrated) of the punches P 12 , P 13  and P 14  and the dies D 12 , D 13  and D 14  disposed on the far side. 
     Far side edges (not illustrated) of the leading edge sections of the punches P 7 , P 8 , P 9 , P 10  and P 11  and the dies D 7 , D 8 , D 9 , D 10  and D 11  are arranged to be an edge of not more than 90 degrees. Also near side edges (not illustrated) of the leading edge sections of the punches P 12 , P 13  and P 14  and the dies D 12 , D 13  and D 14  are arranged to be an edge of not more than 90 degrees. The punches and the dies are moved in the t-direction. By sliding the above mentioned edges of the punches and the dies disposed on the bending area x 2  and of the punches and the dies disposed on the bending area x 1 , the plate-shaped material is cut. Then a slit is formed on the plate-shaped material W. 
     It becomes possible to separate the plate-shaped material W into the bending area x 1  and the bending area x 2  by this slit. A distortion of the plate-shaped material W by a mutual interference of the bending processes in the bending area x 1  and the bending area x 2  can be prevented with this slit. 
     With regards to a description of a processing method, a control device not illustrated controls the bending apparatus  2  so that each of a plurality of moving devices in the bending area x 2  (for example, moving devices  1023 - 1028 ) and each of a plurality of moving devices in the bending area x 1  (for example, moving devices  1013 - 1022 ) move in response to each other. 
     The value of the bending angle θ, for example, θ 7 , θ 13  and θ 14 , which is formed by two surfaces (for example, surfaces w 9  and w 10 , surfaces w 10  and w 17  and surfaces w 17  and w 18 ), that sandwich a ridge (for example, ridges r 12 , r 13  and r 14 ) being a bent section O bent by a plurality of pairs of the punch P and the die D (for example, the punch P 12  and the die D 12 , the punch P 13  and the die D 13  and the punch P 14  and the die D 14 ) disposed in the bending area x 2 , is maintained the same during the bending process. The value of the bending angle θ (for example, θ 8 , θ 9 , θ 10 , θ 11  and θ 12 ), which is formed by two surfaces (for example, surfaces W 11  and W 12 , surfaces W 12  and W 13 , surfaces W 13  and W 14 , surfaces W 14  and W 15  and surfaces W 15  and W 16 ) that sandwich a ridge (for example, ridges r 7 , r 9 , r 10  and r 11 ) being a bent section O bent by a plurality of pairs of the punch P and the die D (for example, the punch P 7  and the die D 7 , the punch P 8  and the die D 8 , the punch P 9  and the die D 9 , and the punch P 10  and the die D 10  and the punch P 11  and the die D 11 ) disposed in the bending area x 1 , is maintained the same during the bending process. Also the surfaces (for example, surfaces w 10 , w 12 , w 14 , w 16  and w 18  and surfaces w 17 , w 8 , w 11 , w 13  and w 15 ) of the plate-shaped material or the extended surface of those surfaces that become parallel to each other at the time of completion of the bending process are maintained to be parallel to each other at all times during the bending process. Moving in response to each other refers to controlling and relatively moving the punch and the die, for example, punch P 7  to punch P 14  and die D 7  to die D 14  in the t-direction and the y-direction, in response to each other so that the plate-shaped material W (for example, surfaces w 12 -w 15 ), which is arranged between, for example, the punch unit PU 7  and the punch unit PU 8 , the punch unit PU 8  and the punch unit PU 9 , the punch unit PU 9  and the punch unit PU 10  and the punch unit PU 10  and the punch unit PU 11  disposed adjacent to each other in the y-direction in the bending area x 1 , and so that the plate-shaped material W (for example, surfaces w 10  and w 17 ), which is arranged between the punch unit PU 12  and the punch unit PU 13  and the punch unit PU 13  and the punch unit PU 14  disposed adjacent to each other in the y-direction in the bending area x 2 , maintains a fair surface (straight line in the figure) during the bending process. 
     That is, a bending angle θ (for example, θ 8 , θ 9 , θ 10 , θ 11  and θ 12 ) of each bending section O of the plate-shaped material W is maintained to an equal value at all times during the bending process. Also, surfaces or extended surfaces of the plate-shaped material W, which become mutually parallel at the time of completion of the bending process, are held parallel at all times during the bending process. Hence, the plate-shaped material placed between the punch units collaterally arranged in the y-direction can maintain a fair surface (straight line in the illustration) at all times during the bending process. Therefore, all of the punches P and the dies D of the punch units collaterally arranged in the y-direction are controlled to relatively move in the t-direction and the y-direction. 
     As described above, a bending process is performed to a plurality of places on the plate-shaped material by moving the punch P 7  and die D 7 -the punch P 14  and die D 14  in response to each other and relatively moving the punch P 7  and die D 7 -the punch P 14  and die D 14  to the t-direction and y-direction, respectively. That is, a bending process to a plurality of places can be performed in one process. Therefore, productivity can be improved, and reduction of strength of the completed parts can be prevented without stretching the material just as in a drawing process. 
     A bent sheet metal part having an arbitrary bending angle θ that is less than 180 degrees can be processed by arranging a leading edge section of the punch P 7 -punch P 14  with a triangle-shaped convex section having less than 180 degree angle on a leading edge section and by arranging a leading edge section of the die D 3 -die D 6  with a triangle-shaped concave section having less than 180 degree angle on the trough just as in the punch P 3 -punch P 6 . 
     A bent sheet metal A 3  having 90 degree of a bending angle θ as illustrated in  FIG. 10  can be processed by arranging a leading edge section of the punch P 7 -punch P 14  with a triangle-shaped convex section having 90 degree angle on a leading edge section and by arranging the leading edges of the die D 7 -die D 14  with a triangle-shaped concave section having 90 degree angle on the trough just as in the punch P 7 -punch P 14 . 
     It is desirable that the shape of the leading edge section (convex section of a triangle-shape) of all the punches P is the same, and the shape of the leading edge section (concave section of a triangle-shape) of all the die D is the same. In this case, starting time of the movement of all the punches P and dies D is set to the same time, and speed of the movement of all the punches P and dies D can be set to the same speed. Thus, the control can be simplified. 
     A configuration in which three punch units are arranged in the bending area x 2  has been described above. However, it is needless to mention that not less than three punch units may be arranged in the bending area x 2 . 
     By configuring the bending apparatus  3  with the above described configuration, in addition to the effect from the configuration described in reference with  FIGS. 5 and 6 , a plate-shaped material bending apparatus, which can produce a bent sheet metal having a convex section projected in the opposite direction on the front and the back surface of the plate-shaped material W in the bending area x 1  and the bending area x 2 , can be provided. 
       FIGS. 11 and 12  illustrate explanatory diagrams of a fourth example of a bending apparatus for energizing the punch P and the die D with a motor and bending the near side and the far side in the x-direction of the plate-shaped material differently.  FIG. 13  illustrates a perspective view of a part onto which a different bending process is performed on the near side and the far side in the x-direction being a third direction, which is perpendicular to a first direction (t-direction) and a second direction (y-direction) which is perpendicular to the t-direction. 
     In detail,  FIG. 11  illustrates the time when the plate-shaped material W is set in the bending apparatus  4 .  FIG. 12  illustrates the time when the bending process to the plate-shaped material W has been completed. 
       FIG. 13  illustrates the part onto which a different bending process is performed on the near side and the far side in the x-direction being a third direction, which is perpendicular to a first-direction (t-direction) and a second direction (y-direction) which is perpendicular to the t-direction. 
     “x 1 ” of  FIG. 13  indicates a bending area of the near side in the x-direction of the plate-shaped material W. “x 2 ” of  FIG. 13  indicates a bending area of the far side in the x-direction of the plate-shaped material W. 
     The bending apparatus  4  has one first processing device in the near side (bending area x 1 ) of the plate-shaped material W, two first processing devices and one second processing device in the far side (bending area x 2 ) of the plate-shaped material W. 
     In  FIGS. 11 and 12 , the bending apparatus  4  has a plurality of punch units PU (for example, punch unit PU 15 -punch unit PU 19 ) for bending and pressing the plate-shaped material W with the punch P and the die D. 
     The punch unit PU 15  covering the full width of the plate-shaped material W is disposed on the upper section of the other punch units in the figure. The punch units PU 17 , PU 18  and PU 19  are collaterally disposed in the y-direction on the far side in the x-direction of the plate-shaped material W (bending area x 2 ). The punch unit PU 16  is disposed in the y-direction on the near side in the x-direction of the plate-shaped material W (bending area x 1 ). 
     Here, a plurality of punch units PU (for example, punch units PU 15 -PU 19 ) is arranged so that the bending direction against the plate-shaped material W becomes opposite of that of the adjacent punch units. With regards to the spatial relationship of each of the punch P and the die D to the surface of the plate-shaped material W, for example, in the bending area x 1 , the punch P 16  of the punch unit PU 16  is disposed on the surface W 1  side and the die D 16  is disposed on the surface W 2  side with respect to the die D 15  of the punch unit PU 15  being disposed on the surface W 1  side and the punch P 15  of the punch unit PU 15  being disposed on the surface W 2  side. In the bending area x 2 , the punch P 17  of the punch unit PU 17  is disposed on the surface W 1  side and the die D 17  of the punch unit PU 17  is disposed on the surface W 2  side with respect to the die D 15  of the punch unit PU 15  being disposed on the surface W 1  side and the punch P 15  of the punch unit PU 15  being disposed on the surface W 2  side. Also, the die D 18  of the punch unit PU 18  is disposed on the surface W 1  side and the punch P 18  of the punch unit PU 18  is disposed on the surface W 2  side with respect to the die D 17  of the punch unit PU 17  being disposed on the surface W 1  side and the Punch P 17  of the punch unit PU 17  being disposed on the surface W 2  side. Also, the punch P 19  of the punch unit PU 19  is disposed on the surface W 1  side and the die D 19  of the punch unit PU 19  is disposed on the surface W 2  side with respect to the die D 18  of the punch unit PU 18  being disposed on the surface W 1  side and the punch P 18  of the punch unit PU 18  being disposed on the surface W 2  side. 
     That is, the punch units PU 17 , PU 16  and PU 19  being the first processing device are capable of bending one surface of the plate-shaped material W to not more than 180 degrees by pressing the plate-shaped material W. The punch units PU 15  and PU 18  being the second processing device are capable of bending the other surface of the plate-shaped material W to not more than 180 degrees by pressing the plate-shaped material W. 
     Thereby, the plate-shaped material W has a convex section in each of the bending area x 1  and the bending area x 2  whose projected direction oppose each other. 
     A moving device  1029 , which enables the punch P 15  to move in the y-direction and the t-direction simultaneously, is connected to the punch P 15  of the punch unit PU 15 . A moving device  1030 , which enables the die D 15  to move in the y-direction and the t-direction simultaneously, is connected to the die D 15  of the punch unit PU 15 . 
     A moving device  1033 , which enables the punch P 17  to move in the y-direction and the t-direction simultaneously, is connected to the punch P 17  of the punch unit PU 17 . A moving device  1030 , which enables the die D 17  to move in the y-direction and the t-direction simultaneously, is connected to the die D 75  of the punch unit PU 17 . 
     In the similar manner, moving devices  1031  and  1032 , which enable the punch P 16  and the die D 16  to move in the y-direction and the t-direction simultaneously, is connected to the punch P 16  and the die D 16  of the punch unit PU 16 . Moving devices  1035  and  1036 , which enable the punch P 18  and the die D 18  to move in the y-direction and the t-direction simultaneously, is connected to the punch P 18  and the die D 18  of the punch unit PU 18 . Moving devices  1037  and  1038 , which enable the punch P 19  and the die D 19  to move in the y-direction and the t-direction simultaneously, is connected to the punch P 19  and the die D 19  of the punch unit PU 19 . 
     The punch P 15  and the die D 15  have the length that is the same as the width of the plate-shaped material W or the length that is not less than the width of the plate-shaped material W in the x-direction. The punch P 16  and the die D 16  disposed on the near side have the length that is the same as the width of the bending area x 1  or the length that is not less than the width of the bending area x 1  in the x-direction. The punches P 17 , P 18  and P 19  and the dies D 17 , D 18  and D 19  disposed on the far side have the length that is the same as the width of the bending area x 2  or the length that is not less than the width of the bending area x 1  in x-direction. 
     The far side edges (not illustrated) of the punch P 16  and the die D 16  disposed on the near side come slidably in contact with the near side edges (not illustrated) of the punches P 17 , P 18  and P 19  and the dies D 17 , D 18  and D 19  disposed on the far side. Far side edges (not illustrated) of the leading edge sections of the punch P 16  and the die D 16  are arranged to be an edge of not more than 90 degrees. Also near side edges (not illustrated) of the leading edge sections of the punches P 17 , P 18  and P 19  and the dies D 17 , D 18  and D 19  are arranged to be an edge of not more than 90 degrees. The punches and the dies are moved in the t-direction. By sliding the above mentioned edges of the punches and the dies disposed on the bending area x 2  and of the punches and the dies disposed on the bending area x 1 , the plate-shaped material is cut. Then a slit is formed on the plate-shaped material W. 
     Since this slit separates the plate-shaped material W into the bending area x 1  and the bending area x 2 , a distortion of the plate-shaped material W by a mutual interference of the bending in the bending area x 1  and the bending area x 2  can be prevented with this slit. 
     With regards to the description of a processing method, a non-illustrated control device controls a plurality of moving devices, for example, the moving devices  1029 - 1038 , so that the plurality of moving devices moves in response to each other. 
     Here, moving in response to each other refers to as following. 
     The value of the bending angle θ, for example, θ 15 , θ 17 , θ 18  and θ 19 , which is formed by two surfaces (for example, surfaces w 19  and w 20 , surfaces w 20  and w 23 , surfaces w 23  and w 24  and surfaces w 24  and w 2 ), that sandwich a ridge (for example, ridges r 15 , r 16 , r 18  and r 19 ) being a bent section O bent by a plurality of pairs of the punch P and the die D (for example, the punch P 15  and the die D 15 , the punch P 16  and the die D 16 , the punch P 18  and the die D 18  and the punch P 19  and the die D 19 ) disposed in the bending area x 2 , is maintained the same during the bending process. The value of the bending angle θ (for example, θ 15  and θ 16 ), which is formed by two surfaces (for example, surfaces w 19  and w 20  and surfaces w 21  and w 22 ), that sandwich a ridge (for example, ridges r 15  and r 17 ) being a bent section O bent by a plurality of pairs of the punch P and the die D (for example, the punch P 15  and the die D 15  and the punch P 17  and the die D 17 ) disposed in the bending area x 1 , is maintained the same during the bending process. Also the surfaces (for example, surfaces w 19 , w 23 , w 22  and w 25  and surfaces w 20  (w 21 ) and w 24 ) of the plate-shaped material that become parallel to each other at the time of completion of the bending process or the extended surface of those surfaces are maintained to be parallel to each other at all times during the bending process. Hence, moving in response to each other refers to controlling and relatively moving the punch and the die, for example, punch P 15  to punch P 19  and die D 15  to die D 19 , in the t-direction and the y-direction in response to each other so that the plate-shaped material W (for example, surfaces w 20  and w 21 ), which is arranged between the punch unit PU 15  and the punch unit PU 17  disposed adjacent to each other in the y-direction in the bending area x 1 , and the plate-shaped material W (for example, surfaces w 20 , w 23  and w 24 ), which is arranged between the punch unit PU 15  and the punch unit PU 16 , the punch unit PU 16  and the punch unit PU 18  and the punch unit PU 18  and the punch unit PU 19  disposed adjacent to each other in the y-direction in the bending area x 2 , maintains a fair surface (straight line in the figure) during the bending process. 
     As described above, a bending is performed on a plurality of places on the plate-shaped material by moving the punch P 15  and die D 15 -the punch P 19  and die D 19  in response to each other and relatively moving the punch P 15  and die D 15 -the punch P 19  and die D 19  to the t-direction and y-direction, respectively. That is, a bending on a plurality of places can be performed in one process. Therefore, productivity can be improved, and reduction of strength of the completed parts can be prevented without stretching the material just as in a drawing process. 
     By configuring the bending apparatus  3  with the above described configuration, in addition to the effect from the configuration described in reference with  FIGS. 5 and 6 , a plate-shaped material bending apparatus, which can produce a bent sheet metal part A 4  having a convex section projected in the opposite direction on the front and the back surface of the plate-shaped material W in the bending area x 1  and the bending area x 2  and a flange (surface W 19 ), can be provided. 
     The punch unit PU 15  can be removed from the configuration described above. In this case, a plate-shaped material bending apparatus that is capable of producing a bent sheet metal (not illustrated), which has a convex section projected in the opposite direction on the front and the back side of the plate-shaped material W in the bending area x 1  and the bending area x 2 , can be provided. 
     A bent sheet metal part having an arbitrary bending angle θ that is less than 180 degrees can be processed by arranging a leading edge section of the punch P 15 -punch P 19  with a triangle-shaped convex section having not more than 180 degree angle on a leading edge section and by arranging a leading edge section of the die D 15 -die D 19  with a triangle-shaped concave section having not more than 180 degree angle on the trough just as in the punch P 15 -punch P 19 . 
     A bending angle θ of 90 degrees as illustrated in  FIG. 13  can be realized by arranging a leading edge section of the punch P 15 -punch P 19  with a triangle-shaped convex section having 90 degree angle on a leading edge section and by arranging the leading edges of the die D 15 -die D 19  with a triangle-shaped concave section having 90 degree angle on the trough just as in the punch P 15 -punch P 19 . 
     It is desirable that the shape of the leading edge section (convex section of a triangle-shape) of all the punches P is the same, and the shape of the leading edge section (concave section of a triangle shape) of all the die D is the same. In this case, starting time of the movement of all the punches P and dies D is set to the same time, and speed of the movement of all the punches P and dies D can be set to the same speed. Thus, the control can be simplified. 
       FIGS. 14 and 15  illustrate explanatory diagrams of a fifth example of a bending apparatus, which energizes the punch P and the die D via a linkage mechanism and bends the plate-shaped material W.  FIG. 16  illustrates a perspective view of a part onto which a bending process has been performed by having the bending apparatus  5  press the plate-shaped material W. 
     In detail,  FIG. 14  illustrates the time when the plate-shaped material W has been set to the bending apparatus  5 .  FIG. 15  illustrates the time when the bending process to the plate-shaped material. W has been completed. 
     In  FIGS. 14 and 15 , the bending apparatus  5  is configured by a link section L, which press and bends the plate-shaped material W, and a press section PR, which serves as a bending driving force. For example, a press machine, which uses oil pressure and is usually employed, can be used for the press section PR. The press section PR includes a pedestal PR 1 , which fixes and holds the link section L, a moving pedestal PR 2 , which is capable of moving in up and down direction of the illustration with respect to the pedestal PR 1 , and a main body PR 3 , which moves the moving pedestal PR 2  up and down with oil pressure. 
     A pedestal L 1  of the link section L is fixed onto the pedestal PR 1 . A moving pedestal L 2  of the link section is fixed onto the moving pedestal PR 2 . The bending apparatus  5  is configured so that the bending to the plate-shaped material W can be performed by lowering the moving pedestal L 2  for a predetermined distance with the lowering of the moving pedestal PR 2 . 
     The link section L has a plurality of linkage mechanisms, which bends the plate-shaped material W with the punch and the die. For example, the link section includes a linkage mechanism L 1 , which is equivalent to the first processing device, and a linkage mechanism L 2 , which is equivalent to the second processing mean. The linkage mechanism L 1  is provided between the pedestal L 1  and a moving pedestal L 2 . The linkage mechanism L 2  is provided on a punch P 50  and a die D 50 . 
     The linkage mechanism L 1  includes a first link L 11  and a second link L 12 , which move the punch  50  in y-direction and t-direction as drawing a circle while maintaining parallel with respect to the pedestal L 1 , and a third link L 13  and a fourth link L 14 , which move the die D 50  in y-direction and t-direction as drawing a circle while maintaining a parallel with respect to the pedestal L 1 . Each of the first link L 11 , the second link L 12 , the third link L 13  and the fourth link L 14  are configured by a pair of parallel links. 
     The linkage mechanism L 2  includes a fifth link L 21 , which moves the punch  51  in y-direction and t-direction as drawing a circle while maintaining parallel with respect to the die D 50 , a seventh link L 23 , which energizes the punch P 51 , a seventh link L 23 , which moves the die D 51  in y-direction and t-direction as drawing a circle while maintaining parallel with respect to the punch P 50 , and an eighth link L 24 , which energizes the die D 51 . The fifth link L 21  and the sixth link L 23  are configured by a pair of parallel links. 
     The linkage mechanism L 2  moves the punch  51  and the die  51  to reduce the interval of the die  51  and the punch  51  with respect to the punch  50  and the die D 50  in y-direction while reducing the interval of the punch P 51  and the die D 51  in t-direction. 
     A plurality of punch units disposed adjacent to each other in y-direction, (for example, the set of the punch P 50  and the die D 50 , and the set of the punch P 51  and the die D 51 ) is arranged so that the bending direction of the punch unit to the surface of the plate-shaped material opposes from that of the adjacent punch unit. For example, the punch units are arranged so that the die D 51  is disposed on the surface W 1  side and the punch P 51  is disposed on the surface W 2  side with respect to the punch P 50  disposed on the surface W 1  side and the die D 50  disposed on the surface W 2  side. 
     That is, the punch P 50  and the die D 50  being the first processing device are capable of bending one surface of the plate-shaped material W to not more than 180 degrees by pressing the plate-shaped material W. The punch P 51  and the die D 51  being the second processing device are capable of bending the other surface of the plate-shaped material W to not more than 180 degrees by pressing the plate-shaped material W. 
     By utilizing a bending apparatus having the above described configuration, a bending process, which bends the plate-shaped material W into a Z shape, is performed on the plate-shaped material W. 
     The punch P 50  and the die D 50 , and the punch P 51  and the die D 51  have a length that is the same as the width of the plate-shaped material W in the x-direction or a length that is not less than the width of the plate-shaped material W in the x-direction. 
     The linkage mechanism L 1  will be described in detail. One end of the first link L 11  is pivotally fixed onto a moving pedestal L 2  by a pivot  501 . The other end of the first link L 11  is pivotally fixed onto the punch P 50  by a pivot  503 . One end of the second link L 12  is pivotally fixed onto the pedestal L 1  by a pivot  502 . The other end of the second link L 12  is pivotally fixed onto the punch P 50  by a pivot  503 . 
     The first link L 11  and the second link L 12  enable the punch P 50  to move as drawing a circle while maintaining parallel to the pedestal L 1 . With regards to the spatial relationship of pivots of the first link L 11  and the second link L 12 , since the punch P 50  moves to the leading edge side in response with the movement of the moving pedestal L 2 , in the t-direction, the pivots  501  and the pivots  502  are arranged on a straight line parallel to the y-axis and the pivots  503  is arranged on the right-hand side of the straight line in the figure. 
     In case when the moving pedestal PR 2  descends, the first link L 11  and the second link L 12  moves the punch P 50  towards the leading edge side and the lower side of the figure as drawing a circle while maintaining a parallel to the pedestal L 1 . 
     One end of the third link L 13  is pivotally fixed onto a moving pedestal L 2  by a pivot  504 . The other end of the third link L 13  is pivotally fixed onto the punch D 50  by a pivot  506 . One end of the fourth link L 14  is pivotally fixed onto the pedestal L 1  by a pivot  505 . The other end of the fourth link L 14  is pivotally fixed onto the punch D 50  by a pivot  506 . 
     The third link L 13  and the fourth link L 14  enables the die D 50  to move as drawing a circle while maintaining a parallel to the pedestal L 1 . With regards to the spatial relationship of pivots of the third link L 13  and the fourth link L 14 , since the die D 50  moves to the opposite direction of the leading edge side, in the t-direction, the pivots  504  and the pivots  505  are arranged on a straight line parallel to the y-axis and the pivots  506  is arranged on the left-hand side of the straight line in the figure. 
     In case when the moving pedestal PR 2  descends, the third link L 13  and the fourth link L 14  move the die D 50  into the opposite direction of the leading edge side and the lower side of the figure as drawing a circle while maintaining a parallel to the pedestal L 1 . 
     In response to the movement of the punch P 50  and the die D 50 , the leading edges of the punch P 50  and the die D 50  come in contact with each other via the plate-shaped material W and the surface W 1  of the plate-shaped material W is bent to not more than 180 degrees. 
     The linkage mechanism L 2  will be described in detail. One end of the fifth link L 21  is pivotally fixed onto the die D 50  by a pivot  507 . The other end of the fifth link L 21  is pivotally fixed onto the punch P 51  by a pivot  508 . The fifth link L 21  enables the punch P 51  to move as drawing a circle while maintaining a parallel to the die D 50 . Then, the punch P 51  is moved to the leading edge. Therefore, one end of the sixth link L 22  is pivotally fixed onto a pivot  509  of the projection section  141  of the fourth link L 14  and the other end of the sixth link L 22  is pivotally fixed onto a pivot  510  of the punch P 51 . 
     In case when the moving pedestal PR 2  descends, the fifth link L 21  and the sixth link L 22  move the punch P 51  toward the leading edge so as to reduce the separation distance to the die  50  as drawing a circle while maintaining a parallel to the die D 50 . 
     One end of the seventh link L 23  is pivotally fixed onto the punch P 50  by a pivot  511 . The other end of the seventh link L 23  is pivotally fixed onto the die D 50  by a pivot  512 . The seventh link  123  enables the die D 51  to move as drawing a circle while maintaining a parallel to the punch P 50 . Then the die D 51  is energized to the opposite side of the leading edge. Therefore, one end of the eighth link L 24  is pivotally fixed onto a pivot  513  of a projection section  121  of the first link L 11  and the other end of the eighth link L 24  is pivotally fixed onto a pivot  514  of the die D 51 . 
     In case when the moving pedestal PR 2  descends, the seventh link L 23  and the eighth link L 24  moves the die D 51  into the opposite direction of the leading edge so as to reduce the interval to the punch  50  in the y-direction while maintaining a parallel to the punch P 50 . 
     A relative movement amount of the punch P 51  and the die D 51  in the t-direction is the amount in which the leading edges of the punch P 51  and the die D 51  comes in contact with each other via the plate-shaped material W. The movement of the punch P 51  and the die D 51  bends the surface W 2  of the plate-shaped material W to not more than 180 degrees. 
     As described above, the punch P 51  moves according to the movement of the die D 50  via the fifth link  121  and the sixth link L 22 . The die D 51  moves according to the movement of the punch P 50  via the seventh link L 23  and the eighth link L 24 . Hence, a plurality of punch units (for example, a set of punch P 50  and the die D 50  and a set of punch P 51  and the die D 51 ) can move in response to each other. 
     That is, the movement of the punch P 50  and the die D 50  bends the surface W 1  of the plate-shaped material W to not more than 180 degrees. By moving the punch P 51  and the die D 51  in response to (in accordance to) the movement of the punch P 50  and the die D 50 , the surface W 2  of the plate-shaped material W is bent to not more than 180 degrees. Hence, a Z-shaped bending is realized. 
     In the configuration above, the value of the bending angle θ, for example, θ 1  and θ 2 , which are formed by surfaces, for example, surfaces w 1  and w 2  and surfaces w 2  and w 3 , that sandwich a ridge, for example, a ridges r 1  and r 2 , being a bent section bent by the punch P and the die D, is maintained the same value during the bending process. Also the surfaces of the plate-shaped material (for example, surfaces w 1  and w 3 ) that become parallel to each other at the time of completion of the bending process or the extended surface of those surfaces are maintained to be parallel to each other at all times during the bending process. Hence, in order to have all of the plate-shaped material W arranged between the pairs of the punch and the die (for example, a set of punch P 50  and the die D 50  with respect to a set of punch P 51  and the die D 51 ) disposed adjacent to each other in the y-direction maintain a fair surface (straight line in the figure) during the bending process, the length of the link (distance of a straight line between pivots) is set up for a descending distance of the pedestal L 1 , a moving distance needed for the punch P and the die D in the t-direction from the start to the completion of the bending process and a distance between both pivots of the link before the bending process starts. 
     For example, in case when considering the third link L 13  as an example, a descending amount (descending distance of the pedestal L 1 ) of the moving pedestal PR 2  of the press section PR is set to y, a moving amount of the punch or the die in the t-direction needed to bend the plate-shaped material W (a moving distance of the punch P and the die D needed from the start to the completion of the bending process in the t-direction) is set to x, an initial gap amount of the pivotal center axis position of the link and the pivot position of the punch and the die (a distance of both pivots of the link in the t-direction before the start of the bending process) in the t-direction is set to a In this case, the length of the link L (distance in a straight line between the pivots) needed to move the punch and the die for a moving amount x can be determined by the following formula.
 
 L   2 =( x   2   +y   2 ){ y   2 +(2 a+x ) 2 }/4 y   2  
 
     By configuring the bending apparatus  5  with the above described configuration, a plurality of pairs of the punch and the die can be moved and driven in response to each other by converting the displacement of one way of the moving pedestal PR 2 . 
     Here, moving in response to each other refers to as following. 
     The value of the bending angle θ for example, θ 1  and θ 2 , which is formed by two surfaces (for example, surfaces w 1  and w 2  and surfaces w 2  and w 3 ), that sandwich a ridge (for example, ridges r 1  and r 2 ) being a bent section O bent by a plurality of pairs of the punch P and the die D (for example, the punch P 50  and the die D 50  and the punch P 51  and the die D 51 ), is maintained the same value during the bending process. Also the surfaces (for example, surfaces w 1  and w 3 ) of the plate-shaped material W that become parallel to each other at the time of completion of the bending process or the extended surface of those surfaces are maintained to be parallel to each other at all times during the bending process. Hence, moving in response to each other refers to controlling and relatively moving the punch and the die, for example, the punch P 50  and the die D 50  and the punch P 51  and the die D 51  in the t-direction and the y-direction, in response to each other so that the plate-shaped material W (for example, surface w 2 ), which is arranged between a set of the punch P 50  and the die D 50  and a set of the punch P 51  and the die D 51  disposed adjacent to each other in the y-direction, maintains a fair surface (straight line in the figure) during the bending process. 
     As described above, a bending is performed on a plurality of places on the plate-shaped material by moving the punch P 50  and die D 50  and the punch P 51  and die D 51  in response to each other and relatively moving the punch P 50  and die D 50  and the punch P 51  and die D 51  to the t-direction and y-direction, respectively. That is, a bending on a plurality of places can be performed in one process. Therefore, productivity can be improved, and reduction of strength of the completed parts can be prevented without stretching the material just as in a drawing process. 
     The leading edge section of a punch is shaped into a convex section of a triangle-shape having less than 180 degrees. The leading edge section of the die is shaped into a concave section of a triangle shape having less than 180 degrees just as in the punch. 
     A bent sheet metal A 5  having 90 degrees of a bending angle θ as illustrated in  FIG. 16  can be processed by arranging a leading edge section of the punch with a triangle shaped convex section having 90 degree angle on a leading edge section and by arranging the leading edge section of the die with a triangle shaped concave section having 90 degree angle on the trough just as in the punch. 
     With the above described configuration, the bending to a plurality of places can be performed in one process. Thus, there is no need to replace the plate-shaped material and the bent sheet metal part can be safely produced while amount of production per unit of time can be increased. 
     Also the plate-shaped material is processed without sliding between the punch and the die. Therefore, a plate-shaped material bending apparatus with high mechanical strength that can produce a high quality bent sheet metal without scratches during the processing while maintaining a required accuracy. 
     And it is desirable that the shape of the leading edge section (convex section of a triangle-shape) of all the punches P is the same, and the shape of the leading edge section (concave section of a triangle-shape) of all of the die D is the same. 
     In this case, a design and structure of a linkage mechanism become simple. 
       FIGS. 17 ,  18  and  19  illustrate explanatory diagrams of a sixth example of a bending apparatus, which energizes the punch P and the die D via a linkage mechanism and bends the plate-shaped material W.  FIG. 20  illustrates a perspective view of a part onto which a different bending process has been performed on the near side and the far side of the plate-shaped material W in the x-direction. 
     In detail,  FIG. 17  illustrates the time when the plate-shaped material W has been set to a bending apparatus  6 .  FIG. 18  illustrates an explanatory diagram of a linkage mechanism L 6  viewed from the same point as  FIG. 17 . 
     In  FIGS. 17 ,  18  and  19 , the bending apparatus  6  includes a link section L, which presses and bends the plate-shaped material W, and above mentioned press section PR (not illustrated) being the driving force of the bending. 
     A pedestal L 1  of the link section L is fixed to a pedestal PR 1  of the press section PR. A moving pedestal L 2  of the link section L is fixed to a moving pedestal PR 2  of the press section PR The bending apparatus  6  is configured so that the bending to the plate-shaped material W can be performed by lowering the moving pedestal L 2  for a predetermined distance with the lowering of the moving pedestal PR 2 . 
     The link section L has a plurality of linkage mechanisms, which bend the plate-shaped material W with the punch and the die. For example, the link section includes a linkage mechanism L 3  and linkage mechanism L 4  being the first processing device, a linkage mechanism L 5  being the second processing mean and a linkage mechanism L 6  being the first processing device. The linkage mechanism L 3  is provided between the pedestal L 1  and a moving pedestal L 2 . The linkage mechanism L 4  and the linkage mechanism L 5  are provided on a punch P 52  and a die D 52 . In the same manner as the linkage mechanism L 3 , the linkage mechanism L 6  is provided between the pedestal L 1  and the moving pedestal L 2 . 
     The linkage mechanism L 3 , linkage mechanism L 4  and linkage mechanism L 5  are disposed on the near side of the x-direction. The linkage mechanism L 6  and the linkage mechanism U are disposed on the far side of the x-direction. The bending apparatus  6  is arranged so that different bending can be performed on the near side of the x-direction and the far side of the x-direction. 
     The linkage mechanism  13  includes an eighth link L 31  and a ninth link L 32 , which move the punch  52  in y-direction and t-direction as drawing a circle while maintaining a parallel with respect to the pedestal L 1 , and a tenth link L 33  and an eleventh link L 34 , which move the die D 52  as drawing a circle while maintaining a parallel to the pedestal L 1 . Each of the eighth link L 31 , the ninth link L 32 , the tenth link L 33  and the eleventh link L 34  is configured by a pair of parallel links. 
     The linkage mechanism L 4  includes a thirteenth link L 41 , which moves the punch P 53  in y-direction and t-direction as drawing a circle while maintaining a parallel to the die D 52 , a fourteenth link L 42 , which energizes the punch P 53 , a fifteenth link L 43 , which moves the die D 53  in y-direction and t-direction as drawing a circle while maintaining a parallel with respect to the punch P 52 , and a sixteenth link L 44 , which energizes the die D 53 . Each of the thirteenth link L 41  and the fifteenth link L 43  are configured by a pair of parallel links. 
     The linkage mechanism L 4  moves the punch  53  and the die  53  to reduce the interval of the die  53  and the punch  53  with respect to the punch  52  and the die D 52  in y-direction while reducing the interval of the punch P 53  and the die D 53  in t-direction. 
     The linkage mechanism L 5  includes a sixteenth link L 51 , which moves the punch P 54  in y-direction and t-direction as drawing a circle while maintaining a parallel to the die D 52 , a seventeenth link L 52 , which energizes the punch P 54 , a eighteenth link L 53 , which moves the die D 54  in y-direction and t-direction as drawing a circle while maintaining a parallel to the punch P 52 , and a nineteenth link L 54 , which energizes the die D 54 . Each of the sixteenth link L 51  and the eighteenth link L 53  is configured by a pair of parallel links. 
     The linkage mechanism L 5  moves the punch  54  and the die  54  to reduce the interval of the die  54  and the punch  54  with respect to the punch  52  and the die D 52  in y-direction while reducing the interval of the punch P 54  and the die D 54  in t-direction. 
     A plurality of punch units disposed adjacent to each other in y-direction, for example, the punch P 53  and the die D 53 , the punch P 52  and the die D 52  and the punch P 54  and the die D 54 , which are disposed on the near side of the x-direction, is arranged so that the bending direction of the punch unit to the surface of the plate-shaped material differs from that of the adjacent punch unit. 
     In detail, for example, the die D 52  is disposed on the surface W 2  side and the punch P 52  is disposed on the surface W 1  side where the punch P 53  is disposed on the surface W 2  side and the die D 53  is disposed on the surface W 1  side. Also, the punch P 54  is disposed on the surface W 2  side and the die D 54  is disposed on the surface W 1  side where the die D 52  is disposed on the surface W 2  side and the punch P 52  is disposed on the surface W 1  side. The plurality of punch units is configured as described above so that the bending direction of pairs of the punch and the die disposed adjacent to each other in y-direction against the plate-shaped material W becomes opposite of each other. 
     That is, the punch P 52  and the die D 52  being the first processing device are capable of bending one surface of the plate-shaped material W to not more than 180 degrees by pressing the plate-shaped material W. The punches P 53  and P 54  and the dies D 53  and D 54  being the second processing device are capable of bending the other surface of the plate-shaped material W to not more than 180 degrees by pressing the plate-shaped material W. 
     Each of the above described punch and die has a length that is the same as the width of the bending area x 1  or a length that is not less than the width of the bending area x 1 . 
     The linkage mechanism L 6  disposed in the far side of the linkage mechanisms L 3 , L 4  and L 5  in the x-direction, that is in the bending area x 2  of the far side, has a configuration in which the linkage mechanism L 3  has been rotated 180 degrees centering around a y axis as illustrated in  FIG. 18 . The linkage mechanism L 6  moves the punch P 55  equivalent to the punch P 52  and the die D 55  equivalent to the die D 52  in the t-direction and the y-direction as drawing a circle while maintaining a parallel to the pedestal L 1 . 
     With respect to the spatial relationship of the punch P 55  and the die D 55  to the surface of the plate-shaped material, the punch P 55  and the die D 55  are arranged so that the plate-shaped material W has a convex section projected in opposite direction on the front and the back surface in the bending area x 1  and the bending area x 2 . For example, in the bending area x 2 , the punch P 55  is disposed on the surface W 2  side and the die D 55  is disposed on the surface W 1  side with respect to the punch P 52  disposed on the surface W 1  and the die D 52  disposed on the surface W 2  side in the bending area x 1 . The punch P 55  and the die D 55  have a length that is the same as the length of the bending area x 2  in the x-direction or a length that is not less than the length of the bending area x 2  in the x-direction. 
     The linkage mechanism L 6  includes a twentieths link L 61  (equivalent to the ninth link L 31 ) and the twenty-first link L 62  (equivalent to the tenth link L 32 ), which move the punch P 55  in the t-direction and the y-direction as drawing a circle while maintaining a parallel to the pedestal L 1 , and a twenty-second link L 63  (equivalent to the eleventh link L 33 ) and a twenty-third link L 64  (equivalent to the twelfth link  34 ), which move the die D 55  in the t-direction and the y-direction as drawing a circle while maintaining a parallel to the pedestal L 1 . 
     Here, since the twentieth link L 61 , the twenty-first link L 62 , the twenty-second link L 63  and a twenty-fourth link L 64  have the same configuration and the effect as the ninth link L 31 , tenth link L 32 , eleventh link L 33  and twelfth link L 34 , respectively, a detailed description is omitted. 
     As described above, a bending is performed on a plurality of places on the plate-shaped material by moving the punch P 52  and die D 52 -the punch P 55  and die D 55  in response to each other and relatively moving the punch P 52  and die D 52 -the punch P 55  and die D 55  to the t-direction and y-directions, respectively. That is, a bending on a plurality of places can be performed in one process. Therefore, productivity can be improved, and reduction of strength of the completed parts can be prevented without stretching the material just as in a drawing process. 
     Thereby, the plate-shaped material W has a convex section on each of the bending area x 1  and the bending area x 2  whose projected direction oppose each other. 
     The punches P 53 , P 52  and P 54  and the dies D 53 , D 52  and D 54  disposed on the near side have a length that is the same as the width of the bending area x 1  in the x-direction or a length that is not less than the width of the bending area x 1  in the x-direction. The punch P 55  and the die D 55  disposed on the far side have a length that is equal to or more than the width in the x direction of the bending area x 2 . 
     The far side edges (not illustrated) of the punches P 53 , P 52  and P 54  and the dies D 53 , D 52  and D 54  disposed on the near side come slidably in contact with the near side edges (not illustrated) of the punch P 55  and the die D 55  disposed on the far side. 
     Far side edges (not illustrated) of the leading edge sections of the punches P 53 , P 52  and P 54  and the dies D 53 , D 52  and D 54  are arranged to be an edge of not more than 90 degrees. Also near side edges (not illustrated) of the leading edge sections of the punch P 55  and the die D 55  are arranged to be an edge of not more than 90 degrees. The punches and the dies are moved in the t-direction. By sliding the above mentioned edges of the punches and the dies disposed on the bending area x 2  and of the punches and the dies disposed on the bending area x 1 , the plate-shaped material is cut. Then a slit is formed with the plate-shaped material W. 
     A distortion of the plate-shaped material. W from a mutual interference of the bending in the bending area x 1  and the bending area x 2  can be prevented with this slit. 
     In the configuration above, the value of the bending angle θ, for example, θ 20 , θ 21 , θ 22  and θ 23 , which is formed by two surfaces, for example, surfaces w 26  and w 27 , surfaces w 27  and w 28 , surfaces w 28  and w 29  and surfaces w 30  (w 26 ) and w 31  (w 29 ), that sandwich a ridge, for example, a ridges r 20 , r 21  and r 22 , being a bent section O bent by the punch P and the die D, is maintained the same value during the bending process. Also the surfaces of the plate-shaped material that become parallel to each other at the time of completion of the bending process or the extended surface (for example, surface w 30  or surfaces w 26  and w 28  and surface w 31  or surfaces w 29  and w 27 ) of those surfaces are maintained to be parallel to each other at all times during the bending process. Hence, in order to have all of the plate-shaped material W arranged between the pairs of the punch and the die (for example, for example, the punch P 53  and the die D 53  to the punch P 52  and the die D 52 , the punch P 54  and the die D 54  to the punch P 52  and the die D 52 , the punch P 53  and the die D 53  to the punch P 55  and the die D 55  and the punch P 54  and the die D 54  to the punch P 55  and the die D 55 ) disposed adjacent to each other in the y-direction maintain a fair surface (straight line in the figure) during the bending process, the length of the link (distance of a straight line between pivots) is set for a descending distance of the pedestal L 1 , a moving distance needed for the punch P 52  and the die D 52  in the t-direction from the start to the completion of the bending process and a distance between both pivots of the link before the bending process starts. 
     By configuring the bending apparatus  6  with the above described configuration, a plurality of pairs of the punch and the die can be moved and driven in response to each other by converting the one way displacement of the moving pedestal PR 2 . 
     In  FIGS. 18 and 19 , the value of the bending angle θ, for example, θ 23 , which is formed by two surfaces (for example, surfaces w 30  and w 31 ), that sandwich a ridge (for example, ridge r 23 ) being a bent section O bent by a plurality of pairs of the punch P and the die D (for example, the punch P 55  and the die D 55 ) disposed in the bending area x 2 , is maintained the same value during the bending process. The value of the bending angle θ (for example, θ 21 , θ 20  and θ 22 ), which is formed by two surfaces (for example, surfaces w 27  and w 28 , surfaces w 26  and w 27  and surfaces w 28  and w 29 ), that sandwich a ridge (for example, ridges r 21 , r 20  and r 22 ) being a bent section O bent by a plurality of pairs of the punch P and the die D (for example, the punch P 52  and the die D 52 , the punch P 53  and the die D 53  and the punch P 54  and the die D 54 ) disposed in the bending area x 1 , is maintained the same value during the bending process. Also the surfaces (for example, surfaces w 26 , w 28  and w 30  and surfaces w 29 , w 27  and w 31 ) of the plate-shaped material that become parallel to each other at the time of completion of the bending process or the extended surface of those surfaces are maintained to be parallel to each other at all times during the bending process. Moving in response to each other refers to controlling and relatively moving the punch and the die, for example, punch P 52  to punch P 55  and die D 52  to die D 55  in the t-direction and the y-direction with a linkage mechanism so that the plate-shaped material W (for example, surfaces w 27 , w 28 , w 30  and w 30 ), which is arranged between the punch P 53  and the die D 53 , the punch P 52  and the die D 52  and the punch P 54  and the die D 54  disposed in the y-direction in the bending area x 1  and the punch P 55  and the die D 55  disposed in the y-direction in the bending area x 2 , maintains a fair surface (straight line in the figure) during the bending process. 
     The leading edge section of a punch is formed into a convex section of a triangle shape having not more than 180 degrees. The leading edge section of the die is formed into a concave section of a triangle shape having not more than 180 degrees just as in the punch. Hence, a bent sheet metal part having an arbitrary bending angle not more than 180 degrees can be processed. 
     A bent sheet metal A 6  having 90 degrees of a bending angle θ as illustrated in  FIG. 20  can be processed by arranging a leading edge section of the punch with a triangle-shaped convex section having 90 degree angle on a leading edge section and by arranging the leading edge section of the die with a triangle-shaped concave section having 90 degree angle on the trough just as in the punch. 
     And it is desirable that the shape of the leading edge section (convex section of a triangle shape) of all the punches P is the same, and the shape of the leading edge section (concave section of a triangle shape) of all the die D is the same. In this case, a design and structure of a linkage mechanism become simple. 
     By using the configuring described above, as the same as the effect explained by referring the configuration described in  FIGS. 14 and 15 , there is provided a bent sheet metal having a convex section projected in the opposite direction on the front and the back surface of the plate-shaped material W in the bending area x 1  and the bending area x 2  by the linkage mechanism. 
       FIG. 21  illustrates an explanatory diagram of a seventh example of a part obtained by applying a bending process to the plate-shaped material W. 
     For example, a linkage mechanism that is the same as the linkage mechanism L 3 , the linkage mechanism L 4  and the linkage mechanism L 5  is added to the far side of the linkage mechanism L 6  in the x-direction in the figure as illustrated in  FIGS. 17 and 18 . Hence, as illustrated in  FIG. 21 , a bent sheet metal A 7  having a convex section projected in the opposite direction on the front and the back surfaces of the plate-shaped material W can be produced. 
     A configuration, which forms a limited slit not longer than the length of the plate-shaped material W in the y-direction while the edge of the punch and the die has been bent into the edge shape has been described above in reference to  FIGS. 8 and 9 ,  FIGS. 11 and 12  and  FIGS. 17 ,  18 , and  19 . However, one end of the slit may be extended to the edge of the plate-shaped material W. In this case, a bent part whose one end is cutout can be produces. 
       FIG. 22  illustrates an external view of a plate-shaped material W′ onto which a slit has been formed in advance. 
     A configuration, which forms a slit while bending the sheet metal by using the edge of the punch and the die, has been described above in reference to  FIGS. 8 and 9 ,  FIGS. 11 and 12  and  FIGS. 17 ,  18 , and  19 . However, a plate-shaped material onto which a slit has been formed in advance can be bent as well. 
     With respect to the plate-shaped material W′ onto which a slit has been formed in advance, a slit SL extending to a predetermined width in the y-direction is formed on the boundary of the bending area x 1  of the near side and the bending area x 2  of the far side in the x-direction. The predetermined width is to be not narrower than the variation in the x-direction at the time when plate-shaped material W′ is set to the bending apparatus, for example, approximately 0.5 mm-2 mm. 
     In case when there are at least not less than three bending areas and a plurality of punches and dies is disposed in the x-direction of the bending apparatus, it is needless to mention that at least not less than two slits SL may be provided in advance. 
     The plate-shaped material W′ can be suitably used as a plate-shaped material used in the bending apparatus in which the edges of the punch and the die have not been formed into an edge shape. One end of the slit SL can be structured into an opened cutout state accordingly. 
     It becomes unnecessary to form the edge of the punch and the die into an edge shape by forming a slit on the plate-shaped material in advance. Also the edges of die punches adjacent to each other in the x-direction do not need be slidable. Thus, a plate-shaped material bending apparatus with a good maintenance nature can be realized. 
     A bending has been described above. However, it is needless to mention that the plate-shaped material can be bent by the punch and the die having a leading edge of a circular arch shape. 
     EFFECT OT THE INVENTION 
     With the above described invention, there is provided a processing apparatus and a processing method, which can safely produce a large number of sheet metal parts in a unit time by bending a plate-shaped material having a high mechanical strength while securing the accuracy demanded with little scratches.