Patent Publication Number: US-7721634-B2

Title: Punch tool

Description:
TECHNICAL FIELD 
   The present invention relates to a punch tool including a plurality of punches circularly arranged in a casing, and, particularly to a punch tool where an eccentric load does not act when a punch is drawn out of a workpiece after punching work, and more punches can be arranged. 
   BACKGROUND ART 
   A punch tool including a plurality of punches circularly arranged has a configuration in which a plurality of punches are circularly arranged in a casing attachable to and detachable from a rotating holder mounted on a punch holder rotatably in a punch press, and a striker capable of freely striking each punch is provided to be vertically movable in the upper portion of the casing. An example of a corresponding prior technique is disclosed in Japanese Patent Application Laid-open No. H8-155561. 
   In a configuration described in the above patent publication, a plurality of punches are supported to be vertically movable in a punch mounting portion in the casing, and a head portion of each punch is engaged with a peripheral groove having a cross-sectional shape of a T-shape formed on a striking plate corresponding to the striker. When punching work is performed on a workpiece by each punch, a stripping force for drawing the punch from the workpiece acts on a central portion of the striking plate. 
   Therefore, when the punch is drawn out of the workpiece, an unbalanced load acts on the punch and a bending moment acts thereon, which can cause a jamming phenomenon on a slide guiding portion, such as a sliding portion of the punch or the striking plate. In the configuration of the Patent Document 1, an elastic member is arranged opposite to the center of the lower face of the striking plate. Therefore, a problem arises that it is difficult to doubly arrange a plurality of punches along an inside circle and an outside circle, so that it is difficult to arrange more punches. 
   The present invention has been achieved to solve the above problems, and an object of the present invention is to provide a punch tool where an unbalanced load does not act when a punch is drawn out of a workpiece after punching work, and more punches can be arranged. 
   DISCLOSURE OF THE INVENTION 
   To achieve the above object, a punch tool based on a first aspect of the present invention includes the following: a casing; a plurality of small-diameter punches vertically movable and circularly arranged in the casing; a plurality of large-diameter punches vertically movable and circularly arranged in the casing; a punch driver provided to be vertically movable and relatively rotatable on an upper portion of the casing; and a striker provided on the punch driver to be capable of striking the respective punches; wherein, in the configuration, stripper springs corresponding to the respective small-diameter punches are provided; and the respective large-diameter punches are arranged between the small-diameter punches; and, by the configuration, the stripper springs for the small-diameter punches on both sides of the large-diameter punch act as stripper springs of the large-diameter punch. 
   A punch tool based on a second aspect of the present invention includes the following: a casing; a plurality of punches circularly arranged to be vertically movable in the casing; a punch driver provided to be vertically movable and relatively rotatable on an upper portion of the casing; and a striker provided on the punch driver to be capable of striking the respective punches; where the plurality of punches are arranged on a large-diameter circle outside the casing; the plurality of punches are arranged on a small diameter circle inside the casing; and the punches on the outside circle, and the punches on the inside circle are arranged at positions different in phase. 
   According to a punch tool based on a third aspect of the present invention, which is dependent on the first aspect or the second aspect, in the above punch tool, small-diameter punches and large-diameter punches are arranged alternately at approximately equal intervals on the outside circle; and medium-diameter punches are arranged on the inside circle. 
   According to a punch tool based on a fourth aspect of the present invention, which is dependent on any one of the first aspect to the third aspect, in the above punch tool, stripper springs provided correspondingly to the respective small-diameter punches serve as stripper springs of the large-diameter punches and medium-diameter punches. 
   According to a punch tool based on a fifth aspect of the present invention, which is dependent on any one of the first aspect to the fourth aspect, in the above punch tool, a retainer is provided on the small-diameter punch; another retainer is provided on the large-diameter punch; and a seat portion that supports the retainer provided on the large-diameter punch adjacent to the small-diameter punch is provided on the retainer provided on the small diameter punch. 
   According to a punch tool based on a sixth aspect of the present invention, which is dependent on any one of the first aspect to the fifth aspect, in the above punch tool, striking-force transmitting members for transmitting a striking force of the strikers to the respective punches is provided to be vertically movable on the upper portions of the respective punches. 
   According to a punch tool based on a seventh aspect of the present invention, which is dependent on any one of the first aspect to the sixth aspect, in the above punch tool, a striker portion corresponding to a position where the punch on the outside circle is struck and a striker portion corresponding to a position where the punch on the inside circle is struck are provided on the striker. 
   Therefore, according to the punch tool based on the present invention, since a force, at a time of drawing the punch from the workpiece after punching work to the workpiece is performed by the punch, acts in a direction parallel with the axial center of the punch, a force tending to bend the punch does not act, and a bending moment that acts on the punch does not occur, so that a jamming phenomenon can be eliminated. 
   Since the punches can be doubly arranged along the inside circle and the outside circle, more punches can be provided. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an explanatory sectional view of a punch tool according to an embodiment of the present invention; 
       FIG. 2  is an explanatory sectional view showing an operating state of the punch tool according to the embodiment of the present invention; 
       FIG. 3  is an explanatory sectional view taken along the line III-III in  FIG. 1 ; and 
       FIG. 4(A)  is a plan view showing a configuration of a retainer provided on a small-diameter punch, and  FIG. 4(B)  is a side view showing the configuration of the retainer. 
   

   BEST MODE(S) FOR CARRYING OUT THE INVENTION 
   Preferred embodiments of the present invention will be explained with reference to  FIG. 1  to  FIG. 4 . 
   First, with reference to  FIG. 1 , a punch tool  1  according to an embodiment of the present invention is mounted on a punch holder  3  in a punch press such as a turret punch press to be used. More specifically, a cylindrical rotating holder  5  is rotatably supported in the punch holder  3 , and a cylindrical lifter ring  7  whose lower end portion is fitted in the rotating holder  5  is supported at an upper position of the rotating holder  5 , to be vertically movable and relatively rotatable. 
   In order to rotate the rotating holder  5 , a worm wheel  9  is provided at the upper portion of the rotating holder  5 , and the worm wheel  9  meshes with a worm (not shown), which is controlled and rotated by a servomotor (not shown). Therefore, the rotating holder  5  can be rotated by the servomotor. 
   The lifter ring  7  is supported at a predetermined height position by lifter springs  11  provided at a plurality of portions on the upper face of the punch holder  3 . That is, spring seats  15  are supported to be vertically movable on bolts  13  erectly provided at a plurality of portions on the upper face of the punch holder  3 , and the lifter springs  11  are resiliently mounted between the spring seats  15  and the upper face of the punch holder  3 . The lifter spring  7  is supported by the spring seats  15  at the plurality of portions. The lifter ring  7  is supported so as not to rotate with respect to the rotating holder  5 , namely, so as to make it unrotatable. 
   Since the configuration according to the rotating holder  5 , the lifter ring  7  and the like is a known configuration from the patent document and the like, more detailed explanations regarding the rotating holder  5 , the lifter ring  7  and the like will be omitted. 
   A casing  17  constituting the punch tool  1  is supported to be vertically movable in the cylindrical rotating holder  5 . More specifically, a flange  17 F is provided at the upper portion of the casing  17 , and the flange  17 F is supported on an inner flange  7 F provided on a lower end portion of the lifter ring  7 . That is, the casing  17  is supported to move vertically and integrally with the lifter ring  7 , and the lifter spring  11  has a function of causing the punch tool  1  and the like to ascend and return to the most ascended position. 
   The casing  17  is supported to be vertically movable with respect to the rotating holder  5  and to rotate integrally with the rotating holder  5  via a key (not shown), and a plurality of punches are provided to be vertically movable in the casing  17 . More specifically, a thick punch mounting portion  19  (see  FIG. 3 ) is provided so as to extend in a vertical direction in the casing  17 , and a circular recess upper space  21  is formed on an upper side of the punch mounting portion  19 . 
   Punch mounting holes are provided on a large-diameter outside circle L 1  (see  FIG. 3 ) and a small-diameter inside circle L 2  on the punch mounting portion  19 , respectively. Punch mounting holes  25  for a small-diameter punch  23  and punch mounting holes  29  for a large-diameter punch  27  are provided alternately at approximately equal intervals on the outside circle L 1 . Punch mounting holes  33  for a medium-diameter punch  31  are provided on the inside circle L 2 . 
   The center position of the punch mounting hole  33  for the medium-diameter punch  31  is arranged at a position where a phase is deviated with respect to the centers of the respective punch mounting holes  25  and  29  of the small-diameter punch  23  and the large-diameter punch  27 . In other words, the small-diameter punch  23 , the medium-diameter punch  31 , and the large-diameter punch  27  are arranged in a zig-zag manner, namely, in a staggering manner. 
   A disk-like guide member  37  including punch guide holes  35  that guide the small-diameter punches  23 , the medium-diameter punches  31 , and the large-diameter punches  27  to be vertically movable is detachably attached by a plurality of bolts (not shown) on a lower portion of the punch mounting portion  19  in the casing  17 , and a stripper plate  39  including guiding holes  39 H that guide punch blade portions of the respective punches  23 ,  27 , and  31  is detachably attached on a lower face of the guide member  37  by a plurality of screws (not shown) so as to be replaceable. 
   As shown in  FIG. 1 , a punch head  41  is screwed and fixed integrally on an upper portion of the small-diameter punch  23 , and a retainer  43  is fitted and supported to be vertically movable thereon. A fitting hole  45  (see  FIG. 4(A) ) capable of freely fitting the punch head  41  is provided on the retainer  43 , and the fitting hole  45  is vertically movable with respect to the punch head  41 . A locking step portion  45 A (see  FIG. 4(B) ) capable of freely locking the punch head  41  is then formed on the fitting hole  45  in order that the retainer  43  descends integrally when the punch head  41  descends. 
   Notched portions  43 A,  43 B, and  43 C which are formed by partially notching an outer peripheral face of the retainer  43  are formed at a plurality of portions of the outer peripheral face, and seat portions  47 A,  47 B, and  47 C are formed on the lower portion of the retainer  43  according to the formation of the notched portions  43 A,  43 B, and  43 C. In the retainer  43  provided on the small-diameter punch  23 , the retainers  43  adjacent across the large-diameter punch  27  are formed in a symmetrical shape, as shown in  FIG. 3 . 
   As shown in  FIG. 1 , a small-diameter lifter spring  49  which always biases the small-diameter punch  23  upward to support the same at a predetermined height position in a normal state is resiliently mounted between the small-diameter punch  23  and the guide member  37 . A strong stripper spring  51  for drawing out the small-diameter punch  23  upward after punching work to a workpiece (not shown) is resiliently mounted between the retainer  43  and the guide member  37 . 
   The large-diameter punch  27  is fitted in the punch mounting hole  29  vertically movably, and both sides of a retainer  53  (see  FIG. 3 ) provided on a punch head  52  of the large-diameter punch  27  are projectingly formed toward the retainer  43  side of the small-diameter punch  23  and supported by the seat portions  47 A and  47 C of the retainers  43  adjacent to each other. That is, both the stripper springs  51  for the small-diameter punches  23  adjacent to each other also serve as a stripper spring of the large-diameter punch  27 . 
   Therefore, when the punching work to the workpiece is performed by the large-diameter punch  27 , the large-diameter punch  27  is drawn out of the workpiece by the action of the stripper springs  51  on the both sides, so that a drawing force which is simply twice as large as a drawing force for the small-diameter punch  23  acts on the large-diameter punch  27 . 
   As already understood, since the stripper springs  51  for the small-diameter punches  23  arranged approximately symmetrically on both sides of the large-diameter punch  27  also serve as stripper springs for the large-diameter punch  27 , a bending moment due to an unbalanced load does not act on the large-diameter punch  27 , so that a jamming phenomenon can be suppressed. Also, it is unnecessary to additionally provide a stripper spring for the large-diameter punch  27 . Therefore, a diameter of the punch mounting hole  29  of the large-diameter punch  27  can be made approximately equal to a diameter of the large-diameter punch  27 . Therefore, an arrangement of more punches becomes possible and small-sized entire configuration of the punch tool can be achieved. 
   A stripper spring  55  (see  FIG. 1  and  FIG. 3 ) for the medium-diameter punch  31  is arranged on an inner side beyond the punch mounting hole  33  of the medium-diameter punch  31  (a position nearer the axial center of the casing  17 ) in the punch mounting portion  19  of the casing  17 , and a retainer  57  formed with a seat portion  57 A is provided on an upper portion of the stripper spring  55 . A punch head  59  provided on the medium-diameter punch  31  is supported on the seat portion  57 A of the retainer  57  and the seat portion  47 B of the retainer  43  provided on the small-diameter punch  23 . 
   The seat portion  57 A of the retainer  57  and the seat portion  47 B of the retainer  43  of the small-diameter punch  23  support an approximately symmetrical positions of the punch head  59  in the medium-diameter punch  31 . Therefore, when the medium-diameter punch  31  is drawn out of a workpiece after the punching work to the workpiece performed by the medium-diameter punch  31 , a bending moment does not act on the medium-diameter punch  31 , so that a jamming phenomenon can be suppressed. 
   As already understood, the stripper spring  51  for the small-diameter punch  23  also serves as a stripper spring of the medium-diameter punch  31 . In other words, since the stripper spring  51  for the small-diameter punch  23  and the stripper spring  55  act on the medium-diameter punch  31 , the stripper spring  55  can be downsized to the same extent as the stripper spring  51  for the small-diameter punch  23 , so that the small-sized entire configuration of the punch tool can be achieved. 
   A disk-like ram guide  61  is mounted in the circular recess upper space  21  in the casing  17 , and small rams  63  having a cross-sectional shape of an inverted T-shape corresponding to the punch heads of the respective punches  23 ,  27 , and  31  are supported to be vertically movable on the ram guide  61 . The small rams  63  serve as striking-force transmitting members which transmit striking forces to the respective punches  23 ,  27 , and  31 , when the small rams  63  are struck by strikers described below, and lower faces of the respective small rams  63  abut on the upper faces of the punch heads of the respective punches  23 ,  27 , and  31  to which the respective small rams correspond. Column-shaped upper portions of the respective small rams  63  project upward from the ram guide  61 , and the height positions of the upper faces of the respective small rams  63  are set to be approximately equal. 
   According to this configuration, even when the respective punches  23 ,  27 , and  31  are arranged closely to one another, the small-diameter column-shaped upper portions of the respective small rams  63  can be arranged to be separated relatively largely from one another. 
   A guide flange  67  including a large circular recess portion  65  on its lower face central portion is integrally attached by fixing units such as a plurality of bolts on the flange  17 F in the casing  17 , and a driver guide  69  is supported, only relatively rotatably by a plurality of bearings  71  in a central portion of the guide flange  67 . A punch driver  73  is supported to be vertically movable in the central portion of the driver guide  69 , and a strong elastic member  77  such as a disc spring is resiliently mounted between a head plate  75  attached on an upper end portion of the punch driver  73  projecting upward from the driver guide  69  and a flange  69 F provided on the driver guide  69 . 
   The punch driver  73  is restricted so as not to rotate relative to the driver guide  69  and supported to be movable only vertically, and a key groove  79  (see  FIG. 2 ) extending in a vertical direction is formed on a portion of the punch driver  73  in order to restrict relative rotations. A key  81  engaged with the key groove  79  is fixed on a portion of the driver guide  69 . 
   In order to restrict rotations of the driver guide  69 , a key supporting member  85  including a key  83  is attached integrally on the flange portion  69 F. The key  83  is engaged with a key groove  7 K, extending in a vertical direction, formed on the inner face of the lifter ring  7  to be vertically movable. 
   A large-diameter flange portion  73 F positioned in the recess portion  65  of the guide flange  67  is formed on a lower portion of the punch driver  73 . An outside striker  87  striking (driving) the small-diameter punch  23  and the large-diameter punch  27  arranged on the outside circle L 1  is provided at a predetermined position of a lower face of the flange portion  73 F, and an inside striker  89  striking (driving) the medium-diameter punch  31  arranged on the inside circle L 2  is provided at a predetermined position thereof. 
   The strikers  87  and  89  cause respective punches corresponding to respective small rams  63  to descend by striking upper end faces of the respective small rams  63  individually, and the outside striker  87  and the inside striker  89  are arranged on a line in a diametrical direction (in a radial direction). That is, when the outside striker  87  is located at a position where the outside striker  87  strikes the small ram  63  corresponding to the small-diameter punch  23  and the large-diameter punch  27 , the inside striker  89  is located at a position deviated in a circumferential direction of the inside circle L 2  from the small ram  63  corresponding to the medium-diameter punch  31 . On the contrary, when the inside striker  89  is located at a position where the inside striker  89  strikes the small ram  63  corresponding to the medium-diameter punch  31 , the outside striker  87  is located at a position between the small rams  63  corresponding to the small-diameter punch  23  and the large-diameter punch  27 . It is also possible to integrate the outside striker  87  and the inside striker  89  to make a striker that is long in a radial direction. 
   A die  91  corresponding to the punch tool  1  described above to perform the punching work to a plate-like workpiece includes die holes (not shown) corresponding to the respective punches  23 ,  27  and  31 , and supported by a rotating holder  95  provided rotatably in a die holder  93  provided opposite to the punch holder  3 . The rotating holder  95  is provided to rotate in synchronization with the rotating holder  5 . Since a synchronization rotation mechanism for rotating the lower rotating holder  95  in synchronization with the upper rotating holder  5  and a configuration of the die  91  are heretofore known, detailed explanations of the synchronization rotation mechanism and the configuration of the die  91  and the like will be omitted. 
   In the configuration described above, when the rotating holder  5  is rotated horizontally, the casing  17  supported in the rotating holder  5  is also rotated integrally. On the other hand, since the lifter ring  7 , the driver guide  69 , and the punch driver  73  are in a state that rotations thereof are restricted, the small-diameter punch  23 , the large-diameter punch  27  and the medium-diameter punch  31  can be indexed and positioned below the strikers  87  and  89  provided on the lower face of the punch driver  73 . 
   As shown in  FIG. 1 , when a ram R provided on the punch press to be vertically movable descends to press the head plate  75  downward (to press in a downward direction) after the small-diameter punch  23  is indexed and positioned at a position below the striker  87 , the lifter ring  7  descends against the lifter spring  11  via the elastic member  77 . Therefore, the entirety of the punch tool  1  descends. 
   As described above, when the entirety of the punch tool  1  descends and the stripper plate  39  abuts on a workpiece W on the die  91 , descent of the punch tool  1  is stopped. Thereafter, when the ram R further descends, the elastic member  77  is compressed gradually, and the stripper plate  39  presses and fixes the workpiece W gradually strongly to the die  91  due to a repulsive force of the elastic member  77 . 
   When the striker  87  provided on the punch driver  73  abuts on the small ram  63  corresponding to the small-diameter punch  23  to press the small ram  63  downward by further descending of the ram R in a state that the workpiece W is pressed and fixed, the small-diameter punch  23  descends against biasing forces of the lifter spring  49  and the stripper spring  51  to perform the punching work to the workpiece W in cooperation with the die  91 . 
   Thereafter, when the ram R ascends, the small-diameter punch  23  is drawn out of the workpiece W by the action of the stripper spring  51  and caused to ascend and return to the original position, and the punch driver  73  is caused to ascend and return by the action of the elastic member  77 . The lifter ring  7  and the entirety of the punch tool  1  are caused to return to the original ascending positions by the action of the lifter spring  11 . That is, the lifter ring  7  and the entirety of the punch tool  1  return to the initial state. 
   Next, the punching work is performed on the workpiece W using the large-diameter punch  27  by performing an operation similar to that described above after the large-diameter punch  27  is indexed and positioned at a position below the striker  87 . At this time, when the large-diameter punch  27  descends, the retainers  43  provided on the small-diameter punches  23  positioned on both sides of the large-diameter punch  27  are caused to descend by the retainer  53  provided on the large-diameter punch  27 , and the stripper springs  51  corresponding to the small-diameter punches  23  on the both sides are compressed. However, since each small-diameter punch  23  is supported at a predetermined height position by the lifter spring  49 , each small-diameter punch  23  does not contact the upper face of the workpiece W. 
   Since the stripper springs  51  for the small-diameter punches  23  positioned on the both sides of operates when the large-diameter punch  27  is drawn out of the workpiece W, a force which is twice as large as a force in the case that the small-diameter punch  23  is drawn out of the workpiece acts, so that a large drawing force acts on the large-diameter punch  27 . At this time, since the stripper springs  51  on the both sides act on the large-diameter punch  27  at approximately symmetrical positions, a bending moment or the like does not act on the large-diameter punch  27 , and a jamming phenomenon does not occur on a sliding portion. When the medium-diameter punch  31  is indexed and positioned at a position below the inside striker  89  to perform the punching work to the workpiece, an effect similar to that in the case of the large-diameter punch  27  can be also achieved. 
   As understood from the above explanation, according to the punch tool  1  of the present embodiment, since the stripper springs for the small-diameter punches arranged on the both sides of the large-diameter punch also serve as stripper springs for the large-diameter punch, a bending moment that acts on the large-diameter punch can be suppressed, so that a jamming phenomenon of the sliding portion can be eliminated, arrangement of more punches becomes possible, and the small-sized punch tool can be achieved. 
   Since punches are arranged on the outside large-diameter circle and the inside small-diameter circle, respectively, and the punches on the outside circle and the punches on the inside circle are arranged at different phases, downsizing of the entire configuration and compactedness of the punch tool can be achieved by arranging the outside circle and the inside circle closely, and more punches can be arranged. 
   Further, since there is a configuration in which the small ram serving as a striking-force transmitting member for transmitting a striking force of the striker to each punch is provided to be vertically movable on the upper portion of each punch, only a punch positioned just below the striker is operated without operating adjacent punches even when the retainers provided on respective punches are arranged closely so as to interfere with one another. 
   The embodiment of the present invention described above is to be considered not restrictive, and the invention can be embodied in other various forms, as changes are appropriately made. 
   Note that the disclosure of Japanese Patent Application No. 2004-187880 (filed on Jun. 25, 2004) is incorporated by reference herein in their entirety.