Abstract:
A punching device of the present invention is proposed which can perform positional alignment with high accuracy without generating positional deviation or vibration by shifting a workpiece, and which does not deteriorate the accuracy of determining the position of an image by shifting a photographic device. In this punching device, a CCD camera, which can photograph the position of the die hole upon the lower die and the position of the pattern upon the workpiece which shows the position thereon where punching is to be performed, is fixedly provided at a position removed from the raising and lowering track of the punch plate. Furthermore, a mirror may be provided between the CCD camera and the die hole upon the lower die.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a punching device which punches a hole of a specified shape in a plate shaped workpiece, and to a workpiece processing method which utilizes this punching device.  
           [0003]    2. Description of the Prior Art  
           [0004]    When punching a hole of a specified shape in a plate shaped workpiece, a punching device has been employed which comprises a die in the upper surface of which a die hole is formed, and a punch which can be raised and lowered with respect to this die so as to enter into the die hole of the die. And a pattern which shows the positions to be punched is provided upon a workpiece which can be processed by being punched using this type of punching device, so that the punching process can be performed with high accuracy when this pattern is accurately aligned with the die hole. In order to do this, a punching device has been developed in which a photographic device is provided for detecting the position of the workpiece. In this punching device, position determination for the punching process is performed by shifting the workpiece to a position in which it can be photographed by the photographic device, and when performing punching, the workpiece is further shifted to the correct position for being punched.  
           [0005]    Furthermore, a punching device in which the position of the workpiece is detected by photography without shifting the workpiece has been developed, and has been disclosed in Japanese Patent Application, First Publication No. Hei 10-118995. This punching device performs position determination of the workpiece by shifting the photographic device to an axis which joins the die hole of the die and the punch, and when punching is to be performed, the photographic device is removed away from the above described axis, so that the punching process can be performed.  
           [0006]    However, with the former prior art punching device, when shifting the workpiece from the photographic position to the punching position, there is the problem that the accuracy deteriorates due to occurrence of positional deviation between the workpiece and the die, and also that the accuracy becomes further deteriorated due to the length of the distance through which shifting is performed. In addition, the problem also arises that the work efficiency is poor, because, after the shifting has stopped, it is necessary to wait until vibration set up by the shifting has died away.  
           [0007]    Furthermore, with the latter prior art punching device, the problem arises that detection of the position of the workpiece at high accuracy cannot be anticipated, since the photographic device is frequently shifted, and accordingly the position of the photographic device when detecting the position of the workpiece is not necessarily always the same.  
         SUMMARY OF THE INVENTION  
         [0008]    The present invention has been made in consideration of the above described problems with the prior art, and its objective is to provide a punching device, and a workpiece processing method which utilizes said punching device, which can perform position determination at high accuracy, without generating positional deviation or vibration by shifting the workpiece, and without deteriorating the accuracy of detection of the position of the workpiece by shifting the photographic device.  
           [0009]    In order to attain the above described objective, the present invention proposes, according to its device aspect, a punching device, comprising: a main stand, to which is fixed a die which is provided with a die hole in its upper surface; a table, which is provided so as to be shiftable with respect to the main stand, which is formed with a hole approximately in its central portion for exposing the die, and which further is made so that a workpiece can be mounted upon its upper surface; a shift mechanism which shifts the table with respect to the main stand; a raising and lowering mechanism which is arranged above the table and raises and lowers a punch plate to which is fitted a punch which can be engaged into the die hole; a first photographic device, which is fixed in a position removed from the raising and lowering track of the punch plate, and which photographs a first image which shows the position of the die hole in the die, and a second image which shows the position of a pattern which indicates the position upon the workpiece which is to be punched; and a shifting control means which controls the shift mechanism according to the first and second images which are photographed by the first photographic device, so as, by shifting the table, to align the position of the pattern which indicates the position upon the workpiece which is to be punched to the position of the die hole in the die.  
           [0010]    It should be understood that, in the above specified structure, by a portion being removed from the raising and lowering track of the punch plate, is meant that this portion is removed from the axis which joins the die hole and the punch, so that it is acceptable for the first photographic device to be set up in any position in which it does not obstruct the raising and lowering of the punch plate to which the punch is fitted. For example, it is acceptable for the first photographic device to be fixed at the side of the axis which joins the die hole and the punch, and to photograph the workpiece upon the table and the die hole from above at a slanting angle.  
           [0011]    In this case, it is desirable for the shift mechanism to shift the table with respect to the main stand in two mutually perpendicular directions in a horizontal plane. Furthermore, in this case, it is further desirable for the shift mechanism to further rotate the table with respect to the main stand within the horizontal plane around a vertical axis.  
           [0012]    According to the characteristics of the present invention as specified above, since the first photographic device which detects the position of the die hole in the die and the position of the pattern which indicates the position upon the workpiece which is to be punched is provided in a position removed from the raising and lowering track of the punch plate, thereby images can be photographed which show the position of the die hole in the die and the position of the pattern which indicates the position upon the workpiece which is to be punched, with the first photographic device fixed just as it is, and moreover without shifting the workpiece. And the shifting control means controls the shift mechanism according to the images which are photographed by the first photographic device, so as, by shifting the table, to align the position of the pattern which indicates the position upon the workpiece which is to be punched to the position of the die hole in the die. As a result, according to the present invention, it becomes possible to perform positional alignment of the workpiece with high accuracy without generating positional deviation or vibration by shifting the workpiece or the first photographic device.  
           [0013]    Furthermore, according to a more particular aspect of the present invention, it is desirable for this punching device further to include a second photographic device which is fixed in a position removed from the raising and lowering track of the punch plate, and which photographs an image which shows the position of the die hole in the die, and the position of the pattern which shows the position upon the workpiece which is to be punched; and a monitor device which displays the image which is photographed by the second photographic device.  
           [0014]    In this case, by the operator fixing the workpiece in a suitable position upon the table while observing the monitor device, the shifting control means, in cooperation with the first photographic device, is enabled to perform alignment of the position of the pattern which shows the position upon the workpiece which is to be punched to the position of the die hole in the die by shifting the table.  
           [0015]    Moreover, in this case, it is not necessary to utilize a photographic device of high accuracy for the second photographic device, since there is no requirement for the operator to position the workpiece with high accuracy when fixing it upon the table. Furthermore, since the alignment of the position of the pattern which shows the position upon the workpiece which is to be punched to the position of the die hole in the die is completed for the time being by this operation, albeit not at high accuracy, thereby it is not necessary for the first photographic device to reproduce an image of such a wide region, and it is possible to reduce the range over which the shift mechanism is required to perform shifting of the workpiece. As a result, according to the present invention, along with it becoming possible to manufacture this punching device at low cost, it is possible further to enhance the positional accuracy for fixing the workpiece.  
           [0016]    Furthermore, according to another more particular aspect of the present invention, it is desirable, in the above described punching device, to interpose a mirror in the optical path between the first photographic device and the table, and for the first photographic device to photograph the first image which shows the position of the die hole in the die, and the second image which shows the position of the pattern which shows the position upon the workpiece which is to be punched, via the mirror. By this structure the degree of freedom for the position for the photographic device is increased, and accordingly the freedom for designing the structure of the punching device itself is increased.  
           [0017]    Furthermore, in order to attain the above described objective, the present invention proposes, according to its method aspect, a workpiece processing method in which a workpiece is subjected to a punching process using a punching device which comprises: a main stand to which is fixed a die which is provided with a die hole in its upper surface; a table which is provided so as to be shiftable with respect to the main stand, which is formed with a hole approximately in its central portion for exposing the die, and which further is made so that a workpiece can be mounted upon its upper surface; and a raising and lowering mechanism which raises and lowers a punch plate to which is fitted a punch which can be engaged into the die hole, which is arranged above the table; comprising: an insertion and fixing step of inserting the workpiece between the table and the punch plate and fixing it to the table, with the die being fixed to the main stand and being exposed through the hole in the table; a step of photographing a first image which shows the position of the die hole in the die with a first photographic device which is fixed in a position removed from the raising and lowering track of the punch plate; a step of, after fixing the workpiece, photographing with the first photographic device a second image which shows the position of a pattern which indicates the position upon the workpiece which is to be punched; an alignment step of shifting the table according to the first and second images so as to align the position of the pattern which indicates the position upon the workpiece which is to be punched to the position of the die hole in the die; and a punching step of, after the alignment step, lowering the punch plate which is fitted to the punch and punching the workpiece.  
           [0018]    With this workpiece processing method, the first photographic device is kept fixed just as it is in its position as removed from the raising and lowering track of the punch plate during the sequence of processes comprising the insertion and fixing step, the alignment step, and the punching step. Furthermore, the workpiece is also not shifted after the alignment step. As a result, according to the present invention, it is possible to perform positional alignment of the workpiece with high accuracy without generating positional deviation or vibration by shifting the workpiece or the first photographic device, and the workpiece can be punched with high accuracy.  
           [0019]    Furthermore, according to a more particular aspect of the present invention, it is desirable, in the above workpiece processing method, for the insertion and fixing step to include: an insertion step of, while photographing an image which shows the position of the die hole in the die and the position of the pattern which shows the position upon the workpiece which is to be punched with a second photographic device which is fixed in a position removed from the raising and lowering track of the punch plate, inserting the workpiece and positioning it upon the table according to the photographic image; and a fixing step of, after inserting the workpiece, fixing the inserted workpiece to the table.  
           [0020]    In this case, it is not necessary to utilize a photographic device of high accuracy for the second photographic device, since there is no requirement for inserting the workpiece with high accuracy when fixing it upon the table in an appropriate position. Furthermore, since the alignment of the position of the pattern which indicates the position upon the workpiece which is to be punched to the position of the die hole in the die is completed for the time being by this insertion and fixing operation, albeit not at high accuracy, thereby it is not necessary for the first photographic device to reproduce an image of such a wide region, and it is possible to align the position of the pattern which indicates the position upon the workpiece which is to be punched to the position of the die hole in the die with high accuracy. Furthermore, in the alignment step, it is possible to manage with a reduced range over which the shift mechanism is required to perform shifting of the workpiece, and it becomes possible to perform alignment of the workpiece with high accuracy and moreover in a short time period, without any requirement for using a large scale photographic device as the first photographic device. 
       
    
    
     BREF DESCRIPTION OF THE DRAWINGS  
       [0021]    [0021]FIG. 1 is a schematic side view showing a preferred embodiment of the punching device according to the present invention.  
         [0022]    [0022]FIG. 2 is a front view showing the punching device of FIG. 1 in its state with a monitor device section removed.  
         [0023]    [0023]FIG. 3 is a plan view showing a main stand of the punching device of FIG. 1.  
         [0024]    [0024]FIG. 4 is an enlarged front view showing essential portions of a raising and lowering mechanism of the punching device of FIG. 1.  
         [0025]    [0025]FIG. 5 is a plan view of an example of a molding die.  
         [0026]    [0026]FIG. 6 is a plan view showing an example of patterns on a workpiece.  
         [0027]    [0027]FIG. 7 is a plan view of an example of a punch plate.  
         [0028]    [0028]FIG. 8 is a plan view of an example of a backing plate.  
         [0029]    [0029]FIG. 9 is a plan view of an example of a stripper.  
         [0030]    [0030]FIG. 10 is a side view showing essential portions of another preferred embodiment of the present invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0031]    The following are preferred embodiments of the present invention will be described with reference to the figures. FIG. 1 is a schematic side view showing of the punching device according to the first preferred embodiment; FIG. 2 is a front view showing this punching device in its state with a monitor device section removed; and FIG. 3 is a plan view showing a main stand of the punching device. This punching device  10  comprises a roughly rectangular shaped main stand  11  which is provided upon a work floor (not shown in the figures), and a main body portion  12  which is provided upon an upper portion of the main stand  11 .  
         [0032]    A table  13  is fitted onto the main stand  11  so as to be shiftable in the horizontal plane. This table  13  can be shifted by an X-axis shift mechanism  14 , a Y-axis shift mechanism  15 , and a θ-axis shift mechanism  16 , respectively, in an X-axis direction in the horizontal plane (the left and right direction with respect to the drawing paper in FIG. 3), a Y-axis direction which is perpendicular to this X-axis direction in the horizontal plane (the upward and downward direction with respect to the drawing paper in FIG. 3), and a θ-axis rotational direction around a vertical axis perpendicular to the X-axis and the Y-axis (the rotational direction around a vertical axis perpendicular to the drawing paper in FIG. 3).  
         [0033]    The table  13  comprises a Y-axis shift section  13   a  which is supported upon the main stand  11  by fixing the side portion thereof and can be shifted along the Y-axis direction, an X-axis shift section  13   b  which is supported upon this Y-axis shift section  13   a  and can be shifted along the X-axis direction, and a θ-axis shift section  13   c  which is supported on this X-axis shift section  13   b  and can be rotated around the θ-axis direction. In more detail, the Y-axis shift section  13   a  is fixed upon four sliding support portions  17   a  which can be shifted along two guide rails  17  which are provided upon the internal bottom surface of the main stand  11  and which extend along the Y-axis direction, and the X-axis shift section  13   b  is fixed upon four sliding support portions  18   a  which can be shifted along two guide rails  18  which are provided upon the upper surface of the Y-axis shift section  13   a  and which extend along the X-axis direction. And the θ-axis shift section  13   c  is mounted upon the X-axis shift section  13   b  so as to be freely rotatable around a shaft portion  19  which is provided upon the upper surface of the X-axis shift section  13   b .  
         [0034]    Accordingly, when the Y-axis shift section  13   a  is shifted along the Y-axis direction, the X-axis shift section  13   b  and the θ-axis shift section  13   c  are also shifted together therewith in the Y-axis direction, and similarly, when the X-axis shift section  13   b  is shifted along the X-axis direction, the θ-axis shift section  13   c  is also shifted together therewith in the X-axis direction. However, when the θ-axis shift section  13   c  is rotated around the θ-axis direction, only this θ-axis shift section  13   c  is rotated around the θ-axis direction by itself.  
         [0035]    Furthermore, the Y-axis shift mechanism  15  comprises a motor  15   a  which is mounted upon the internal bottom surface of the main stand  11  and which comprises a shaft portion  15   b  formed with a screw, and a nut  15   c  which is engaged with this screw and is coupled to the Y-axis shift section  13   a , so that, when the motor  15   a  is driven, the nut  15   c , the Y-axis shift section  13   a , the X-axis shift section  13   b  and the θ-axis shift section  13   c  are shifted together along the Y-axis direction. Further, the X-axis shift mechanism  14  comprises a motor  14   a  which is mounted upon the Y-axis shift section  13   a  and which comprises a shaft portion  14   b  formed with a screw, and a nut  14   c  which is engaged with this screw and is coupled to the X-axis shift section  13   b  so that, when the motor  14   a  is driven, the nut  14   c , the X-axis shift section  13   b  and the θ-axis shift section  13   c  are shifted together along the X-axis direction. Moreover, the θ-axis shift mechanism  16  comprises a motor  16   a  which is mounted upon the X-axis shift section  13   b  and which comprises a shaft portion  16   b  formed with a screw, and a nut  16   c  which is engaged with this screw and is coupled to the θ-axis shift section  13   c  via an engagement structure so that, when the motor  16   a  is driven, the nut  16   c  is shifted along the Y-axis direction, and thereby the θ-axis shift section  13   c  is rotated around the θ-axis direction. The above-mentioned engagement structure comprises a pin which is provided to the nut  16   c  so as to project outwards therefrom, and a groove which is provided upon an edge portion of the θ-axis shift section  13   c , and the width and the length of this groove are made great enough to accommodate this pin so that the pin can be moved therein, and moreover so that they cannot become disengaged due to the rotation of the θ-axis shift section  13   c.    
         [0036]    Yet further, a hole  20  as shown in FIG. 3 is provided roughly in the central portion of the table  13 , and a die  21 , to which a rectangular shaped molding die  21   a  is fitted, is fitted within the central portion thereof so as to be visible through the hole  20 . This die  21  is fixed upon a die base  22  (refer to FIG. 4) so as to be separated from the periphery of the hole  20  by a small gap, and this die base  22  is fixed upon the bottom surface of the main stand  11 . Furthermore, a “C” shaped die hole  21   b  and two holes  21   c  for positional adjustment are pierced in the upper surface of the molding die  21   a , as shown in FIG. 5. And small holes for sucking air (not shown in the figure) are pierced in predetermined positions in the θ-axis shift section  13   c , so that, by the operation of a connected suction device (not shown in the figures) via a hose  23 , a workpiece  24  which is loaded upon the upper surface of the θ-axis shift section  13   c  (refer to FIG. 6) can be fixed down thereto by suction. It should be understood that a gap  11   b  of width equal to the width of the gap between the die  21  and the edge portion of the hole  20  is provided between the outer peripheral portion of the θ-axis shift section  13   c  and an upper surface portion  11   a  of the main stand  11 , so that the θ-axis shift section  13   c  is permitted to move in the horizontal direction by just the length of this gap  11   b.    
         [0037]    Furthermore, the main body portion  12  comprises a box shaped housing section  25  which houses various types of control element and a CPU, and a raising and lowering mechanism  26 . This raising and lowering mechanism  26  is for raising and lowering a punch plate  27  (refer to FIG. 7) which comprises a punch  27   a  which pierces a “C” shaped hole in the workpiece  24  by engaging with the die hole  21   b  of the die  21 , and it is held in a position above the die  21  by a base frame  28  which is fixed upon the side surface of the housing section  25 . Four support cylinders  29  are fixed to this base frame  28 , and four guide shafts  30  are freely slidably inserted inside these support tubes  29 . And a ball nut  32  is fixed in the center of a bridge plate  31  which is fixed upon the upper ends of these guide shafts  30 .  
         [0038]    A ball screw  33  is threaded into this ball nut  32 , and the lower end of this ball screw  33  being linked to a pulley  34  which is fixed to the base frame  28 . Furthermore, this pulley  34  is driven by a motor  36  via an endless belt  35 . Accordingly, when the motor  36  is driven, the pulley  34  is rotated and thereby the ball screw is rotated, so that the ball nut  32  is lowered or raised, and thereby the bridge plate  31  together with the guide shafts  30  are lowered or raised. It should be noted that the motor  36 , as well, is fixed to the base frame  28 .  
         [0039]    As shown in FIG. 4, a guide plate  37  is fitted to the lower ends of the guide shafts  30 , and a punch fitting plate  38  is fitted to the lower surface of this guide plate  37 . Two spring housing holes  39  are provided in the interior of this punch fitting plate  38  with a certain space therebetween, and two coil springs  40  are housed in these spring housing holes  39 . The upper ends of these coil springs  40  press against the lower surface of the guide plate  37 , while their lower ends are engaged against C-rings (circlips)  41 . A backing plate  42  is provided against the lower surface of the punch fitting plate  38 , with the punch plate  27  being provided against the lower surface of this backing plate  42 . Furthermore, a stripper  43  is provided below the punch plate  27  with a small space being maintained therebetween. The upper surface of this backing plate  42  is shown in FIG. 8, and through it there are pierced two pin insertion holes  42   a  and two position determination holes  42   b . Moreover, the upper surface of the punch plate  27  is shown in FIG. 7, and through it there are pierced two pin insertion holes  27   b  whose diameters are somewhat greater than those of the pin insertion holes  42   a  of the backing plate  42 , and two position determination holes  27   c  of the same diameters and in the same positions as the position determination holes  42   b  in the backing plate  42 .  
         [0040]    A circular cylindrical miniature guides  44  are fitted inside the pin insertion holes  27   b . Furthermore, the punch  27   a  which is “C” shaped in cross section is embedded in the central portion of the punch plate  27 , and the lower end of this punch  27   a  projects from the punch plate  27  and extends as far as the lower end of the stripper  43 . The upper surface of the stripper  43  is shown in FIG. 9, and through it there are pierced two pin fixing holes  43   a  and two position determination holes  43   b . And through its central portion, there is pierced a punch insertion hole  43   c  which is “C” shaped in cross section, through which the punch  27   a  can pass.  
         [0041]    Furthermore, pins  45  are inserted through the pin insertion holes  42   a  of the backing plate  42  and through the miniature guides  44  of the punch plate  27 , and the lower ends of these pins  45  are fixed into the pin fixing holes  43   a  of the stripper  43 . These pins  45  extend in the vertical direction, with their upper ends being fixed to the coil springs  40  by the aforementioned C-rings (circlips)  41 . Furthermore, the guide plate  37 , the punch fitting plate  38 , and the backing plate  42  are fixed together by fixing bolts  46 , only one of which is shown in the drawing. Accordingly, the coil springs  40  cannot extend themselves, and can be compressed only by the width of the space between the punch plate  27  and the stripper  43 . It should be noted that the backing plate  42  and the punch plate  27  are also fixed together by bolts which are not shown in the drawing.  
         [0042]    A CCD camera  47  which serves as a first photographic device is fixed to the side surface of the housing section  25  of the main body portion  12 , confronting the die hole  21 b of the die  21 . This CCD camera  47  functions as a photographic device which photographs the position of the die hole  21   b  and the position of a pattern  24   a  on the workpiece  24  which is fixed over the die  21 , and is fitted in a tilted orientation so as to be able to photograph the die hole  21   b  from its upper side at an angle, while avoiding the raising and lowering track of the punch plate  27  etc. so as not to obstruct its raising and lowering.  
         [0043]    Furthermore, a monitor camera  48  which serves as a second photographic device is provided, fixed to the tip end portion of the base frame  28  which supports the raising and lowering mechanism  26 , and confronting the die hole  21   b  of the die  21 , and an image of the die hole  21   b  and of the pattern  24   a  upon the workpiece  24  which is taken by this monitor camera  48  can be projected upon a monitor device  49  which is provided upon the front side of the raising and lowering mechanism  26 . This monitor camera  48  is also disposed in a tilted orientation so as to avoid the raising and lowering track of the punch plate  27  etc., just like the CCD camera  47 .  
         [0044]    An X-axis control section  50  which controls the shifting of the X-axis shift section  13   b  in the X-axis direction, a Y-axis control section  51  which controls the shifting of the Y-axis shift section  13   b  in the Y-axis direction, a θ-axis control section  52  which controls the rotation of the θ-axis shift section  13   c  around the θ-axis, and a punch control section  53  which controls the raising and lowering of the punch  27   a  are housed in the lower portion of the housing section  25 .  
         [0045]    Furthermore, a CPU  54  for image processing and position control, and valves  55  for controlling the above-mentioned suction device, are provided in the upper portion of the housing section  25 . The CPU  54  functions to input the image which is taken by the CCD camera  47 , to perform image processing thereupon so as to convert it into positional data, and to output the difference between two sets of positional data (as will be described hereinafter) as correction data to the X-axis control section  50 , the Y-axis control section  51 , and the θ-axis control section  52 .  
         [0046]    With this type of structure, when performing a punching process upon the workpiece  24  following a pattern  24   a  upon the workpiece  24  like that shown in FIG. 6, first, in the state of the apparatus with the punch  27   a  and so on raised up by the raising and lowering mechanism  26 , the die hole  21   b  of the die  21  is photographed by the CCD camera  47 . By doing this, the image data produced thereby is transmitted to the CPU  54  and is image processed into positional data which is stored in the storage section (not shown in the figures). Next, the operator loads the workpiece  24  upon the θ-axis shift section  13   c  while viewing the image photographed by the monitor camera  48  upon the monitor device  49 , so that the pattern  24   a  upon the workpiece  24  is roughly in alignment with the die hole  21   b . Next, the suction device is operated by actuating the valves  55  upon the housing section  25 , and thereby the workpiece  24  is fixed upon the θ-axis shift section  13   c.    
         [0047]    And the pattern  24   a  on the workpiece  24  is photographed by the CCD camera  47 . The image data resulting therefrom are transmitted to the CPU  54  and are image processed into positional data, which is then stored in the storage section. The difference between the positional data for this pattern  24   a  and the previously obtained positional data for the die hole  21   b  is subjected by the CPU  54  to calculation processing as a deviation, so as to yield correction data. And, based upon this correction data, the CPU  54  outputs correction commands to the X-axis control section  50 , the Y-axis control section  51 , and the θ-axis control section  52 .  
         [0048]    These control sections  50 ,  51 ,  52  which have received these correction commands shift the workpiece  24  to an appropriate position by shifting the table  13  by driving the appropriate motors. In other words, the X-axis control section  50  drives the motor  14   a  and shifts the X-axis shift section  13   b  along the X-axis to an appropriate position, and the Y-axis control section  51  drives the motor  15   a  and shifts the Y-axis shift section  13   a  along the Y-axis to an appropriate position. Furthermore, the θ-axis control section  52  drives the motor  16   a  and rotates the θ-axis shift section  13   c  around the θ-axis to an appropriate position, while not disturbing its position along the X-axis and along the Y-axis. As a result, the pattern  24   a  upon the workpiece  24  comes to be accurately aligned with the die hole  21   b . And then the punch  27   a  is lowered, and a “C” shaped hole is pierced through the workpiece  24  in the appropriate location thereupon.  
         [0049]    In the operation at this time, first, the portion of the raising and lowering mechanism  26  which performs raising and lowering is lowered, and the stripper  43  comes into contact with the die  21 . Thereafter the lowering is further continued, and, since the pins  45  slide freely through the punch plate  27  and the backing plate  42 , the stripper  43  and the pin  45  compress the coil springs  40 , and are raised up relative to the punch plate  27  etc.. As a result the punch  27   a  projects from the bottom surface of the stripper  43  and engages with the die hole  21   b , thus piercing the workpiece  24 .  
         [0050]    By repeating the above described operations, it is possible to pierce the workpiece  24  along all the patterns  24   a  thereupon. In this manner it becomes unnecessary to shift the CCD camera  47  or the workpiece  24 , since with this punching device  10  the CCD camera  47  is provided fixed to a portion which is removed from the raising and lowering track of the raising and lowering mechanism  26 . Therefore, positional determination for the workpiece  24  at high accuracy is possible, as a result, the accuracy of the punching process can be enhanced.  
         [0051]    It should be noted that, in this sequence of operations, the actions of fitting the workpiece  24  and actuating the valves  55  are performed by executing a standard program provided in advance. Furthermore, the lowering of the punch plate  27  and so on is performed by commands being outputted from the CPU  54  to the punch control section  53 , when the pattern  24   a  on the workpiece  24  and the die hole  21   b  have been mutually aligned, and the punch control section  53  drives the motor  36  based upon these commands.  
         [0052]    Furthermore, as another preferred embodiment of the present invention, as shown in FIG. 10, it is possible to dispose a mirror  56  below the stripper  43  in the optical path between the CCD camera  47  shown by two-dot chain lines and the die  21 . In this case, the CCD camera  47  is not disposed above the θ-axis shift section at an angle, but, as shown by the CCD camera  47  drawn in solid lines in the figure, can be disposed in any of various positions in parallel with the θ-axis shift section  13   c . Furthermore, in this case, when performing the punching process, the mirror  56  is shifted to a position away from the raising and lowering track of the punch plate  27 .  
         [0053]    In this case as well, positional determination at high accuracy can be performed, since it is only the mirror  56  which is shifted, which has no particular influence upon the accuracy of the positional determination. Furthermore, it would be possible to dispose the mirror  56  from the beginning in a position removed from the raising and lowering track. When this is done, the structure of the device is further simplified, since no mechanism for shifting the mirror  56  is required. The other beneficial operational results of this preferred embodiments are the same as those of the first preferred embodiment described above.  
         [0054]    It should be understood that, although in the disclosed preferred embodiments the main stand  11  was fixed and the table  13  was shifted, as an alternative construction, it would also be possible for the main stand  11  to be shifted, while the table  13  was fixed. In such a case, the structure would include a fixing stand to which the table  13  was fixed, and the main stand  11  would be shifted with respect to this fixing stand. Thus, in the punching device  10  according to the present invention, either of the above described structures may be employed, provided that the relative positions of the main stand  11  and the table  13  can be varied.  
         [0055]    It should be understood that, although the present invention has been shown and described in terms of certain preferred embodiments thereof, and with reference to the drawings, various modifications of the details of any preferred embodiment of the present invention could be made without departing from its scope, which is accordingly to be defined solely by the appended Claims.