Abstract:
A cutting device for cutting a flat workpiece includes a nibbler that continuously punches the workpiece, and a fluid spraying device that sprays a fluid onto the surface of the workpiece. The nibbler includes a cylindrical case, a punch that has a punch blade for punching the workpiece and that is accommodated in the case to have reciprocating motion in the vertical direction, and a die provided below the case. The cutting device is configured to move the workpiece interposed between the case and die in a prescribed direction while continuously punching the workpiece with the punch. The fluid spraying device has a spray port from which the fluid is discharged and is configured so the fluid is discharged from the spray port in the direction in which the punch approaches the die. The spray port of the fluid spraying device is disposed near the punch blade of the punch.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a cutting apparatus and cutting method for cutting a sheet-like workpiece. 
       BACKGROUND ART 
       [0002]    Conventionally, a nibbler is widely known as a device for cutting a sheet-like workpiece (for example, a steel sheet) (for example, see JP 9-234622 A). 
         [0003]    Generally, the nibbler includes a cylindrical case, a punch arranged in the case, which reciprocates in a top-bottom direction, and a die arranged below the case. The nibbler cuts the workpiece by punching the workpiece continuously with the punch, while moving in a prescribed direction with the sheet-like workpiece interposed between the case and the die. 
         [0004]    In the nibbler configured as described above, the workpiece comes in contact with the side of the punch after punting the workpiece with the punch. 
         [0005]    Therefore, a part of the workpiece coming in contact with the punch is lifted up according to the punch rising, and falls by elastic force of the workpiece. That is, the workpiece is intermittently lifted up according to the reciprocating motion of the punch, and is vibrated. 
         [0006]    If the workpiece is vibrated, the position of the part of the workpiece being cut is not stabilized. Therefore, it is difficult to cut the workpiece with the nibbler with high precision. 
         [0007]    Further, the part of the workpiece lifted up by the punch falls and crashes against the die, so that the undesirable noise occurs in the work environment. 
         [0008]    A means for solving the above problems includes fixing the workpiece. 
         [0009]    However, an unwanted part of the workpiece falls under its own weight after removed by the nibbler, so that it is difficult to fix the unwanted part. A complicated mechanism of the apparatus is required to fix the unwanted part of the workpiece, so that it is disadvantageous in that cost for cutting the workpiece is increased. 
         [0010]    Further, the means for solving the above problems includes reducing the distance between the case and the die in the nibbler. The workpiece is fixed between the case and the die by reducing the distance between the case and the die to a value substantially equal to the thickness of the workpiece, which prevents the workpiece from being lifted up by the punch. 
         [0011]    However, when the workpiece is cut by the nibbler, the case and the die interfere with the workpiece, so that it is disadvantageous in that the shape of the workpiece cut by the nibbler is restricted. 
       CITATION LIST 
     Patent Literature 
       [0012]    PTL1: JP 9-234622 A 
       SUMMARY OF INVENTION 
     Technical Problem 
       [0013]    The object of the present invention is to suppress vibration of the workpiece at low cost and to cut a workpiece with high precision. 
       Solution to Problem 
       [0014]    A first aspect of the invention is a cutting apparatus for cutting a sheet-like workpiece including a nibbler that continuously punches the workpiece, at least one fluid jetting device that jets a fluid onto a surface of the workpiece. The nibbler includes a cylindrical case, a punch that has a blade for punching the workpiece and that is housed in the case to reciprocate in a top-bottom direction, and a die provided below the case, and the nibbler is configured to punch continuously the workpiece interposed between the case and the die with the punch while the nibbler moves in a prescribed direction. The fluid jetting device has a jet port from which the fluid is jetted and is configured to jet the fluid from the jet port in a direction in which the punch approaches the die. The jet port of the fluid jetting device is disposed near the blade of the punch. 
         [0015]    Preferably, the jet port of at least one fluid jetting device is disposed to at least one of both sides in a direction orthogonal to the top-bottom direction and a direction in which the nibbler moves, relative to the blade of the punch. 
         [0016]    A second aspect of the invention is a cutting method for cutting a sheet-like workpiece including a first step of preparing a nibbler that includes a cylindrical case, a punch that has a blade for punching the workpiece and that is housed in the case to reciprocate in a top-bottom direction, and a die provided below the case, a second step of preparing a fluid jetting device that jets a fluid onto a surface of the workpiece in a direction in which the punch approaches the die, and a third step of punching continuously the workpiece interposed between the case and the die in a prescribed direction with the punch while making the nibbler move in a prescribed direction. The fluid is jetted onto a part of the workpiece near the blade by the fluid jetting device in the third step. 
       Advantageous Effects of Invention 
       [0017]    The present invention makes it possible to suppress vibration of the workpiece at low cost and to cut a workpiece with high precision. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0018]      FIG. 1  shows a cutting apparatus according to an embodiment of the present invention. 
           [0019]      FIG. 2( a )  is a sectional view showing the cutting apparatus according to the embodiment of the present invention, and  FIG. 2( b )  is an end view taken along line A-A of  FIG. 2( a ) . 
           [0020]      FIG. 3  shows a position of a fluid jetting device of a first alternative embodiment of the cutting apparatus according to the present invention. 
           [0021]      FIG. 4  shows the first alternative embodiment of the cutting apparatus according to the present invention. 
           [0022]      FIG. 5  shows a shape of a fluid jetting device of a second alternative embodiment of the cutting apparatus according to the present invention. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0023]    With reference to drawings, a cutting apparatus  1  as an embodiment of a cutting apparatus according to the present invention is described below. 
         [0024]    For convenience of explanation, the top-bottom direction in the  FIG. 1  is defined as the top-bottom direction of the cutting apparatus  1 . 
         [0025]    As shown in  FIG. 1 , the cutting apparatus  1  cuts a workpiece W. The cutting apparatus  1  cuts the workpiece W to remove a scrap part Ws which is an unwanted part of the workpiece W. The cutting apparatus  1  may be configured to be griped by an operator to cut the workpiece W manually, or to be attached to a robot arm to cut the workpiece W automatically. 
         [0026]    The workpiece W is a sheet (for example, a steel sheet) to be cut by the cutting apparatus  1 . The workpiece W is placed on a placing table P. The workpiece W is disposed such that the scrap part Ws is not situated on the placing table P. A part of the workpiece W coming in contact with the placing table P is pressed toward the placing table P by a clamp C. That is, the workpiece W is fixed by clamping only a part to be the final product (herein after referred to as a “product part”) with the placing table P and the clamp C. Therefore, the scrap part Ws removed by the cutting apparatus  1  falls under weight thereof, and is discarded suitably. 
         [0027]    The cutting apparatus  1  includes a nibbler  10  and a fluid jetting device  20 . 
         [0028]    As shown in  FIGS. 2( a ) and 2( b ) , the nibbler  10  is a device moving in a prescribed direction while continuously punching the workpiece W, and includes a case  11 , a punch  12 , a supporting part  13 , a die  14 , a driving part  15 . 
         [0029]    Additionally, the horizontal white painted arrow in  FIG. 2( a )  shows the direction in which the nibbler  10  (exactly the cutting apparatus  1 ) moves. 
         [0030]    The case  11  is formed in substantially a cylinder extending in the top-bottom direction, and the lower end part thereof is open. 
         [0031]    The punch  12  is housed in the case  11  so as to slide in the top-bottom direction. 
         [0032]    The supporting part  13  is fixed to the inner circumferential surface of the case  11 , and supports the case  11  and the die  14 . 
         [0033]    The punch  12  reciprocates in the top-bottom direction at a predetermined frequency, and punches the workpiece W. The punch  12  has a blade  12   a , and a connecting part  12   b.    
         [0034]    The blade  12   a  has a sectional shape of substantially a horseshoe, and the lower end thereof is formed as a blade edge for punching the workpiece W. The blade  12   a  protrudes downward from the lower end of the case  11  to enter an after-mentioned die hole  14   a  of the die  14  when the punch  12  arrives at the bottom dead center. 
         [0035]    The connecting part  12   b  is connected to the driving part  15  so that the driving part  15  reciprocates the punch  12  in the top-bottom direction. 
         [0036]    The supporting part  13  is a member which supports the case  11  and the die  14 . The upper end part of the supporting part  13  is fixed to the inner circumferential surface of the case  11 , and the supporting part  13  extends downward from the inside of the case  11 . The supporting part  13  has such a shape that an opening coincident with the sectional shape of the blade  12   a  is formed on the lower end surface of the case  11 . In other words, a space in which the punch  12  is housed is formed between the case  11  and a part of the supporting part  13  inserted into the case  11 , and the opening of the space formed on the lower end surface of the case  11  has the shape coincident with the sectional shape of the blade  12   a.    
         [0037]    The die  14  is fixed to the lower end part of the supporting part  13 . 
         [0038]    The die  14  is arranged below the case  11  so as to be on the opposite side of the case  11  across the workpiece W. The die  14  is formed in substantially a cylinder. The die  14  is fixed to the supporting part  13  so as to cover the lower end part of the supporting part  13 . The die  14  has the die hole  14   a , and an ejecting hole  14   b.    
         [0039]    The die hole  14   a  is formed so that the blade  12   a  enter thereinto when the punch  12  arrives at the bottom dead center. Specifically, the die hole  14   a  is formed between the die  14  and a part of the supporting part  13  inserted into the die  14 . The die hole  14   a  has the shape coincident with the sectional shape of the blade  12   a , and opens on the upper end surface of the die  14 . 
         [0040]    The ejecting hole  14   b  is a hole through which a crescentic scrap S punched from the workpiece W by the punch  12  is ejected to the outside of the die  14 . The ejecting hole  14   b  is formed on the lateral surface of the die  14 , and communicates with the die hole  14   a.    
         [0041]    The driving part  15  reciprocates the punch  12  in the top-bottom direction at a predetermined frequency. The driving part  15  has a connecting part  15   a , a rod  15   b , and a motor  15   c.    
         [0042]    The connecting part  15   a  is connected to the connecting part  12   b  of the punch  12 . 
         [0043]    The rod  15   b  is connected to the motor  15   c  and the connecting part  15   a  so as to transmit power of the motor  15   c  to the connecting part  15   a.    
         [0044]    The motor  15   c  transmits power to the connecting part  15   a  through the rod  15   b . Revolution of the motor  15   c  (see the arrow on the motor  15   c  in  FIG. 2 ) is converted into vertical movement of the connecting part  15   a  through the rod  15   b. [ 0023 ]    
         [0045]    As mentioned above, the nibbler  10  makes the punch  12  reciprocate in the top-bottom direction (direction in which the punch  12  moves into and out of proximity with the die  14 ) while moving in a predetermined direction with the workpiece W interposed between the case  11  and the die  14 , thereby continuously punching the workpiece W. 
         [0046]    The fluid jetting device  20  is formed substantially in a tube extending in the top-bottom direction, and is configured to jet the fluid downward (toward the surface of the workpiece W) from a jet port  20   a  formed on the lower end thereof. The fluid jetting device  20  is controlled by a prescribed controller to jet the fluid at the predetermined pressure while the nibbler  10  is working the workpiece W. The fluid jetting device  20  is provided to keep a positional relationship to the nibbler  10 . In the present embodiment, the fluid jetting device  20  is fixed on the outer circumferential surface of the case  11  of the nibbler  10 , and the jet port  20   a  is situated at the side of the blade  12   a.    
         [0047]    Additionally, gas such as compressed air, and liquid such as water and cutting oil may be adapted as the fluid jetted from the fluid jetting device  20 , but the compressed air is preferably adapted from the viewpoint of cost, work efficiency and the like. 
         [0048]    As shown in  FIG. 2( a ) , the fluid jetting device  20  is disposed such that the jet port  20   a  is situated near the surface of the workpiece W. In other words, the fluid jetting device  20  is disposed such that the jet port  20   a  is separated by a prescribed distance from the surface of the workpiece W, and is disposed to be able to jet the fluid at a short distance of the surface of the workpiece W. 
         [0049]    As shown in  FIG. 2( b ) , the fluid jetting device  20  is disposed such that the jet port  20   a  is situated near the blade  12   a  of the punch  12 . In other words, the fluid jetting device  20  is disposed to jet the fluid onto the part of the workpiece W near the blade  12   a . In the present embodiment, the jet port  20   a  of the fluid jetting device  20  is disposed away from the blade  12   a  in the direction in which the nibbler  10  is moved. For further details, the fluid jetting device  20  is disposed such that the jet port  20   a  is situated outward of the case  11  and is situated at a position away from the blade  12   a  in the direction in which the nibbler  10  is moved (the right direction in  FIG. 2( b ) ). 
         [0050]    As mentioned previously, in the workpiece W, only the product part is fixed by the placing table P and the clamp C, and a part to be cut off by the cutting apparatus  1  is not fixed (see  FIG. 1 ). 
         [0051]    Therefore, if the workpiece W is cut with only the nibbler  10 , a part of the workpiece W corning in contact with the blade  12   a  is intermittently lifted up according to the reciprocating motion of the punch  12 , and the workpiece W is vibrated. 
         [0052]    However, the cutting apparatus  1  jets fluid at the predetermined pressure from above toward a part of the workpiece W which may be lifted up by the punch  12 , that is, a part of the workpiece W near the blade  12   a , by disposing the jet port  20   a  of the fluid jetting device  20  near the blade  12   a  of the punch  12 . 
         [0053]    Hereby, the force acts on the workpiece W against the direction in which the workpiece W is lifted up by the punch  12  by the fluid jetted through the jet port  20   a , and therefore it is possible to suppress that the part of the workpiece W coming in contact with the blade  12   a  is lifted up intermittently by the reciprocating motion of the punch  12 . 
         [0054]    Accordingly, it is possible to suppress the vibration of the workpiece W, and therefore it is possible to cut the workpiece W with high precision and to suppress noise generated when the workpiece W crashes against the die  14 . 
         [0055]    Furthermore, it is possible to suppress vibration of the workpiece W without fixing the scrap part Ws and the like, and therefore it is possible to reduce cost for cutting the workpiece W. 
         [0056]    Further, it is possible to suppress vibration of the workpiece W without making a change such that the shape of the workpiece W which is cut off by the nibbler  10  is limited, such as reducing distance between the case  11  and the die  14  as same level as the thickness (the vertical dimensions in  FIG. 2( a ) ) of the workpiece W. 
         [0057]    Further, it is possible to suppress vibration of the workpiece W by jetting the fluid on the surface of the workpiece W, and therefore it is possible to cut various shapes of workpieces. 
         [0058]    Additionally, the pressure at which the fluid jetting device  20  jets the fluid is set to such a value that the workpiece W is not lifted up by the punch  12 . The fluid is preferably jetted onto the part as near as possible to the blade  12   a  in the workpiece W to suppress vibration of the workpiece W at the pressure as low as possible. 
         [0059]    A fluid jetting device may be configured to jet the fluid through a clearance between the case  11  and the blade  12   a  in order to jet the fluid onto the part extremely near the blade  12   a  in the workpiece W. 
         [0060]    Further, the fluid jetting device  20  fixed on the case  11  of the nibbler  10 , has only to move the nibbler  10  in order to jet the fluid along the moving locus of the nibbler  10 , and therefore it is possible to suppress vibration of the workpiece W with a simple configuration. 
         [0061]    In the present embodiment, one fluid jetting device  20  is provided, but the number of the fluid jetting device is not limited, and a plurality of the fluid jetting devices may be provided. 
         [0062]    For example, as shown in  FIG. 3 , three fluid jetting devices  20 A,  20 B and  20 C may be provided. 
         [0063]    Each of the fluid jetting devices  20 A,  20 B and  20 C is configured to jet the fluid onto the part of the workpiece W near the blade  12   a  as well as the fluid jetting device  20 . 
         [0064]    Additionally, the white painted arrow in  FIG. 3  shows the direction in which the nibbler  10  (exactly the cutting apparatus  1 ) moves. 
         [0065]    The fluid jetting device  20 A is disposed as well as the fluid jetting devices  20 . For further details, the fluid jetting device  20 A is disposed such that a jet port  20 Aa thereof is situated outward of the case  11  and in an advanced position from the blade  12   a  in the direction in which the nibbler  10  moves (the right direction in  FIG. 3 ). 
         [0066]    In the fluid jetting device  20 B, a jet port  20 Ba thereof is disposed to one side (the upper side in  FIG. 3 ) of a direction orthogonal to the top-bottom direction and the direction in which the nibbler  10  moves, relative to the blade  12   a . For further details, the fluid jetting devices  20 B is disposed such that the jet port  20 Ba thereof is situated outward of the case  11  and in advanced position from the blade  12   a  to one side (the upper direction in  FIG. 3 ) of a direction orthogonal to the top-bottom direction and the direction in which the nibbler  10  moves. 
         [0067]    In the fluid jetting device  20 C, a jet port  20 Ca thereof is disposed to the other side (the lower side in  FIG. 3 ) of a direction orthogonal to the top-bottom direction and the direction in which the nibbler  10  moves, relative to the blade  12   a . For further details, the fluid jetting devices  20 B is disposed such that the jet port  20 Ca thereof is situated outward of the case  11  and in an advanced position from the blade  12   a  to the other side (the lower direction in  FIG. 3 ) of the direction orthogonal to the top-bottom direction and the direction in which the nibbler  10  moves. 
         [0068]    As shown in  FIG. 4 , if the fluid jetting devices  20 B and  20 C is provided in addition to the fluid jetting device  20 A which is disposed as well as the fluid jetting devices  20 , the fluid jetting device  20 B jets the fluid onto the scrap part Ws of the workpiece W and the fluid jetting device  20 C jets the fluid onto the product part of the workpiece W when the workpiece W is cut. 
         [0069]    In this way, three fluid jetting devices  20 A,  20 B and  20 C jet the fluid onto a plurality of positions around the blade  12   a  in the workpiece W, and therefore it is possible to further suppress vibration of the workpiece W. 
         [0070]    In particular, the fluid jetting device  20 B jet onto the scrap part Ws in which the vibration is easily generated without being fixed, and therefore it is possible to suppress vibration of the workpiece W effectively. 
         [0071]    Furthermore, since the fluid jetting device  20 C jets the fluid onto the product part of the workpiece W from above, the fluid press the product part of the workpiece W toward the placing table P. 
         [0072]    Hereby, it is possible to fix the product part of the workpiece W without providing the clamp C for fixing the product part of the workpiece W. 
         [0073]    Accordingly, it is possible to reduce the cost for cutting the workpiece W. 
         [0074]    A fluid jetting device with a jet port which jets to the wide range near the blade  12   a  may be provided instead of providing a plurality of fluid jetting devices. 
         [0075]    For example, as shown in  FIG. 5 , a fluid jetting device  20 D may be provided which has an arc-shaped jet port  20 Da along the outer circumference of the case  11 . 
         [0076]    The fluid jetting device  20 D is shaped along the outer circumference of the case  11  in outward of the case  11  such that the jet port  20 Da is situated from a place advanced from the blade  12   a  in the direction in which the nibbler  10  moves (the right direction in  FIG. 3 ) to places advanced from the blade  12   a  to one side (the upper direction in  FIG. 5 ) and the other side (the lower direction in  FIG. 5 ) of the direction orthogonal to the top-bottom direction and the direction in which the nibbler  10  moves. 
         [0077]    Herewith, one fluid jetting device  20 D can act as well as the three fluid jetting devices  20 A,  20 B and  20 C. 
       INDUSTRIAL APPLICABILITY 
       [0078]    The present invention is applicable to a cutting apparatus and cutting method for cutting a sheet-like workpiece. 
       REFERENCE SIGNS LIST 
       [0000]    
       
           1 : cutting apparatus 
           10 : nibbler 
           11 : case 
           12 : punch 
           12   a : blade 
           14 : die 
           20 : fluid jetting device 
           20   a : jet port 
         W: workpiece 
         Ws: scrap part