Abstract:
A die includes a stationary die, a movable die, which is opposed to the stationary die and reciprocatable in a first direction to change a distance between the stationary and movable dies, and a transfer mechanism, which transfers a workpiece, upon which plastic deformation work is performed between the stationary and movable dies, in a second direction crossing the first direction. The transfer mechanism includes a clamp portion, which clamps/unclamps the workpiece, a synchronizing member, which is engaged with the movable die to reciprocate in synchronization with reciprocation of the movable die, a clamp-unclamp operation converter, which converts reciprocation of the synchronizing member into clamping/unclamping of the workpiece by the clamp portion, and an advance-return operation converter, which converts reciprocation of the synchronizing member into advance-return operation of the clamp portion, whereby the clamp portion advances the workpiece in the second direction and is returned after advancement of the workpiece.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application is based on and incorporates herein by reference Japanese Patent Application No. 2009-142639 filed on Jun. 15, 2009. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention: 
         [0003]    The present invention relates to a die having a transfer mechanism that transfers a workpiece upon which plastic deformation work, such as press working or forge processing, is performed between a stationary die and movable die. 
         [0004]    2. Description of Related Art: 
         [0005]    Conventionally, a transfer press machine that obtains driving force of a transfer device for a workpiece from a power output of a driving rotatable shaft of the press machine, is known as a transfer press machine that performs press work, which is plastic deformation work (see, for example, Japanese Unexamined Patent Application Publication No. 2004-337953). In addition, a transfer press machine that obtains the driving force of the transfer device from an actuator, which is provided separately from the press machine, is also known (see, for example, Japanese Unexamined Patent Application Publication No. 2005-059080). 
         [0006]    However, in the conventional technology of the above-described Publication No. 2004-337953, a transmission mechanism for transmitting the output of the rotatable shaft of the press machine to an input terminal of the transfer device is necessary. Accordingly, the rotatable shaft of the press machine needs to be adapted for the transmission of the output. Moreover, a rotational position relationship between an output terminal of the rotatable shaft of the press machine and the input terminal of the transfer device considerably influences synchronization between press working operation and transferring operation. Accordingly, work for adjustment of the synchronization becomes complicated. 
         [0007]    In the conventional technology of the above-described Publication No. 2005-059080, the press machine needs to be adapted to include a detecting means for detecting an operating position of the press machine, for the synchronization between press working operation and transferring operation. 
         [0008]    As a result of an elaborate investigation into the above-described problems, the following method for the synchronization between the working and transferring operations has been found. That is, if a transfer mechanism that operates in accordance with a displacement state of a movable die as opposed to a stationary die, is given to a die for performing plastic deformation work on a workpiece, the working operation can be synchronized with the transferring operation without the adaptation of the working machine. 
       SUMMARY OF THE INVENTION 
       [0009]    The present invention addresses at least one of the above disadvantages. 
         [0010]    According to the present invention, there is provided a die for performing plastic deformation work upon a workpiece. The die including a stationary die, a movable die, and a transfer mechanism. The movable die is opposed to the stationary die and reciprocatable in a first direction to change a distance between the stationary die and the movable die. The transfer mechanism is configured to transfer the workpiece, upon which plastic deformation work is performed between the stationary die and the movable die, in a second direction that crosses the first direction. The transfer mechanism includes a clamp portion, a synchronizing member, a clamp-unclamp operation converter, and an advance-return operation converter. The clamp portion is adapted to clamp or unclamp the workpiece. The synchronizing member is engaged with the movable die to reciprocate in synchronization with reciprocal movement of the movable die. The clamp-unclamp operation converter is configured to convert reciprocal movement of the synchronizing member into clamping and unclamping of the workpiece by the clamp portion. The advance-return operation converter is configured to convert the reciprocal movement of the synchronizing member into advance-return operation of the clamp portion, whereby the clamp portion advances the workpiece in the second direction and is returned after advancement of the workpiece. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    The invention, together with additional objectives, features and advantages thereof, will be best understood from the following description, the appended claims and the accompanying drawings in which: 
           [0012]      FIG. 1  is a front view roughly illustrating a structure of a die in accordance with an embodiment of the invention; 
           [0013]      FIG. 2  is a plan view roughly illustrating structures of a lower die and a transfer mechanism of the die; 
           [0014]      FIG. 3  is a perspective view illustrating a main feature of the transfer mechanism; 
           [0015]      FIG. 4  is a front view illustrating the main feature of the transfer mechanism; 
           [0016]      FIG. 5  is a top view illustrating the main feature of the transfer mechanism viewed from an arrow V in  FIG. 4 ; 
           [0017]      FIG. 6  is a side view illustrating the main feature of the transfer mechanism viewed from an arrow VI in  FIG. 4 ; 
           [0018]      FIG. 7  is a timing diagram illustrating an exemplary operation of the die; 
           [0019]      FIG. 8A  is a perspective view illustrating an operating state of the main feature of the transfer mechanism that corresponds to time (A) in  FIG. 7 ; 
           [0020]      FIG. 8B  is a perspective view illustrating an operating state of the main feature of the transfer mechanism that corresponds to time (B) in  FIG. 7 ; 
           [0021]      FIG. 8C  is a perspective view illustrating an operating state of the main feature of the transfer mechanism that corresponds to time (C) in  FIG. 7 ; 
           [0022]      FIG. 8D  is a perspective view illustrating an operating state of the main feature of the transfer mechanism that corresponds to time (D) in  FIG. 7 ; 
           [0023]      FIG. 8E  is a perspective view illustrating an operating state of the main feature of the transfer mechanism that corresponds to time (E) in  FIG. 7 ; 
           [0024]      FIG. 9  is a conceptual diagram illustrating power transmission when the die is used for a press machine; and 
           [0025]      FIG. 10  is a conceptual diagram illustrating power transmission when a die in accordance with a comparative example is used for the press machine. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0026]    An embodiment of the invention is described below with reference to the accompanying drawings. 
         [0027]    As illustrated in  FIG. 1 , a die  1  includes a lower die  2  disposed on an upper surface of a bolster of a press machine (not shown), and an upper die  3  disposed on a lower surface of a slide of the press machine. The lower die  2  may correspond to a stationary die, and the upper die  3  may correspond to a movable die. In accordance with the reciprocation of the slide in upper and lower directions or in a vertical direction, the upper die  3  reciprocates in the upper and lower directions to change a distance in a direction in which the upper die  3  is opposed to the lower die  2 . Plastic deformation work is performed on a workpiece (i.e., a part being worked on) between the lower die  2  and the upper die  3 . 
         [0028]    The die  1  includes a transfer mechanism  4  that transfers the workpiece, which is plastically deformed between the lower die  2  and the upper die  3 , rightward in  FIG. 1 , on the lower die  2 . The transfer mechanism  4  includes a linear crank mechanism  10  disposed on a leftward portion of a working stage (plastic deformation working part) in  FIG. 1 , and a clamping mechanism  20  and a feed mechanism  30  which extend rightward from the linear crank mechanism  10 . 
         [0029]    As illustrated in  FIG. 2 , the transfer mechanism  4  is one of a pair of transfer mechanisms  4 , and the mechanisms  4  transfer the workpiece one after another to the working stage on the right side, with the workpiece clamped by a pair of holding fingers  40  that are opposed to each other. The holding finger  40  may correspond to a clamp portion. Although in  FIG. 2 , more than one holding finger  40  (in the present example, eight holding fingers  40 ), are provided for the transfer mechanism  4 , for instance, in accordance with the number of working stages, a configuration and operation of the transfer mechanism  4  will be described below in reference to  FIGS. 3 to 9 , taking as an example a single holding finger  40 . 
         [0030]    As illustrated in  FIGS. 3 to 6 , the linear crank mechanism  10  extends in the upper and lower directions, and includes a rod  11  and a crank mechanism  12 . An upper end portion of the rod  11  is engaged with the upper die  3  using, for example, a screw or a lock pin, so that the rod  11  is reciprocated in the upper and lower directions in synchronization with the reciprocation of the upper die  3 . The crank mechanism  12  is disposed on a lower end side of the rod  11  and converts the reciprocation of the rod  11  into rotary movement of a rotatable shaft  13 . The rod  11  may correspond to a synchronizing member. The clamping mechanism  20  converts the rotary movement of the rotatable shaft  13  into work clamp-unclamp operation of the holding fingers  40 . The feed mechanism  30  converts the rotary movement of the rotatable shaft  13  into advance-return operation of the holding fingers  40  in rightward and leftward directions (i.e., in a direction of the rotatable shaft  13 ) in  FIG. 4 . The clamping mechanism  20  may correspond to a clamp-unclamp operation converter. The feed mechanism  30  may correspond to an advance-return operation converter. 
         [0031]    The clamping mechanism  20  includes a generally fan-shaped flat plate cam  21 , a swaying block body  22  as a follower, and a clamp base  24 . The flat plate cam  21  is fixed to the rotatable shaft  13  of the crank mechanism  12 , and rotated in accordance with the rotary movement of the rotatable shaft  13 . The swaying block body  22  has a cam follower  22   a  that is in contact with an outer peripheral surface of the flat plate cam  21 , and is displaced (swayed) in the upper and lower directions in accordance with the rotary movement of the flat plate cam  21 . The holding finger  40  is fixed on the clamp base  24 . 
         [0032]    An inclined groove  22   b  (through hole) is formed on the swaying block body  22 . The inclined groove  22   b  is inclined to be further away from the holding finger  40  toward an upper portion of the inclined groove  22   b  in the upper and lower directions. A penetrating bar  23 , which extends in the rightward and leftward directions in  FIG. 4  on the opposite side of the clamp base  24  from the holding finger  40 , is provided to pass through the inclined groove  22   b.  The swaying block body  22  is surrounded with a guide member (not shown), so that the block body  22  is made movable only in the upper and lower directions without being inclined. The swaying block body  22  is constantly urged downward by a spring, for example. 
         [0033]    Accordingly, while the rotatable shaft  13  is rotating, as a result of a cam mechanism that is made up of the flat plate cam  21  and the swaying block body  22 , a function of guiding the penetrating bar  23  along the inclined groove  22   b  and so forth, the holding finger  40 , which is provided to project from the clamp base  24 , alternately repeats a state of clamping the workpiece with its distance to the opposing holding finger  40  reduced, and a state of unclamping the workpiece with its distance to the opposing holding finger  40  increased. 
         [0034]    The swaying block body  22  is surrounded with the guide member, to be allowed to move only in the upper and lower directions. Alternatively, length of the flat plate cam  21  in the direction of the rotatable shaft  13  may be increased not to limit a position of the swaying block body  22  in the direction of the rotatable shaft  13 . 
         [0035]    The feed mechanism  30  includes a cylindrical groove cam  31  and a cam follower  32   a  (see  FIG. 5 ). The groove cam  31  is fixed to the rotatable shaft  13  to rotate in accordance with the rotary movement of the rotatable shaft  13 . The cam follower  32   a  projects into a groove  31   a  formed on an outer peripheral surface of the groove cam  31 . The feed mechanism  30  includes a swaying rod  32 , an operation rod  33 , and a feeding bar  34  having an insertion hole  34   a.  The rod  32  has a supporting point  32   b  at a lower end portion of the rod  32 . The rod  32  is swayed in a shape of a circular arc with its supporting point  32   b  serving as a center in accordance with the rotation of the cylindrical groove cam  31 . The rod  33  projects upward in  FIG. 5  from an upper end portion of the swaying rod  32 . The operation rod  33  is inserted in the hole  34   a  such that the rod  33  is fitted into the hole  34   a  with some play. 
         [0036]    A through hole  34   b  is formed in the feeding bar  34 . The above-described clamp base  24  passes through the hole  34   b.  The clamp base  24  is movable only in upper and lower directions in  FIG. 5  relative to the feeding bar  34 . Accordingly, while the rotatable shaft  13  is rotating, as a result of a cam mechanism that is made up of the cylindrical groove cam  31  and the swaying rod  32 , an engagement relationship between the operation rod  33  and the feeding bar  34 , and so forth, an advancing operation to feed the workpiece by making the holding finger  40 , which is provided to project from the clamp base  24 , proceed rightward in  FIG. 4  in the direction of the rotatable shaft  13 , and a returning operation to return the workpiece by making the holding finger  40  proceed leftward in  FIG. 4 , are alternately repeated. 
         [0037]    As a result of the combination of change of a distance from an shaft center of the shaft  13  to the outer peripheral surface of the flat plate cam  21  fixed to the rotatable shaft  13 , and position change of the groove  31   a  of the cylindrical groove cam  31  fixed to the rotatable shaft  13  in an axial direction of the shaft  13 , the clamp-unclamp operation and the advance-return operation are synchronized. More specifically, as illustrated in  FIG. 7 , in accordance with the reciprocation of the upper die  3  in upper and lower directions, the operation to advance the workpiece with the workpiece clamped (held) by the holding finger  40 , and the operation to return the workpiece with the workpiece unclamped (released) from the holding finger  40  are alternately repeated. 
         [0038]      FIGS. 8A to 8E  illustrate states of a main feature of the transfer mechanism  4  at time (A) to time (E) in the timing diagram in  FIG. 7 . 
         [0039]    At time (A) in  FIG. 7 , as illustrated in  FIG. 8A , the holding finger  40  is advanced to a maximum extent toward a reverse side of a plane of paper, and holds the workpiece. When the upper die  3  makes the transition to descend from its lifted position and time elapses from time (A) to time (B), because of functions of the rod  11 , the crank mechanism  12 , the cam mechanism of the feed mechanism  30  and so forth, which coordinate with the upper die  3 , as illustrated in  FIG. 8B , the feeding bar  34  is made to proceed rightward, so that the holding finger  40  is also made to proceed rightward, holding the workpiece. 
         [0040]    Then, when the upper die  3  continues going down and time elapses from time (B) to time (C), the holding finger  40  is moved backward to a maximum extent from its maximum forward position toward an upper side of the plane of paper so as to release the workpiece, without changing the position of the feeding bar  34  in rightward and leftward directions as illustrated in  FIG. 8C , owing to functions of the rod  11 , the crank mechanism  12 , the cam mechanism of the clamping mechanism  20  and so forth in synchronization with the upper die  3 . 
         [0041]    When the upper die  3  makes the transition to be lifted up from its lowered position and time elapses from time (C) to time (E), as illustrated in  FIG. 8E , the feeding bar  34  is made to proceed leftward, so that the holding finger  40  is also made to proceed leftward with the holding finger  40  located at its maximum backward position (with the workpiece released), because of the functions of the rod  11 , the crank mechanism  12 , the cam mechanism of the feed mechanism  30  and so forth, which coordinate with the upper die  3 . At time (D) (i.e., at a maximum lowered position or bottom dead point of the upper die  3 ) in the course of the time between time (C) and time (E) when the upper die  3  makes the transition to be lifted up from its lowered position, the workpiece is pressed between the lower die  2  and the upper die  3 . 
         [0042]    When the upper die  3  continues being lifted up and time elapses from time (E) to time (A), owing to functions of the rod  11 , the crank mechanism  12 , the cam mechanism of the clamping mechanism  20  and so forth in synchronization with the upper die  3 , as illustrated in  FIG. 8A , without changing the position of the feeding bar  34  in rightward and leftward directions, the holding finger  40  is advanced to a maximum extent from its maximum backward position toward the reverse side of the plane of paper, so as to hold the workpiece. 
         [0043]    As a result of the above-described configuration and operation of the die  1 , in the transfer mechanism  4  of the die  1 , the rod  11  is engaged with the upper die  3 , so that the rod  11  is synchronized with the reciprocation of the upper die  3  in upper and lower directions. The reciprocation of the rod  11  is converted into the rotary movement of the rotatable shaft  13  in the crank mechanism  12 . The rotary movement of the rotatable shaft  13  is converted in the clamping mechanism  20  into the operation of clamping-unclamping of the workpiece by the holding finger  40 , and the rotary movement of the rotatable shaft  13  is also converted in the feed mechanism  30  into the operation to advance the holding finger  40  in a work transfer direction and to return the holding finger  40  in a counter-work transfer direction, i.e., into the advance-return operation (the holding finger  40  advances the workpiece in a direction that crosses the reciprocation direction of the upper die  3 , and the holding finger  40  is returned after the advancement of the workpiece). 
         [0044]    Accordingly, when the workpiece is pressed between the lower and upper dies  2 ,  3  of the die  1 , the workpiece is transferred by the transfer mechanism  4  in synchronization with the reciprocation of the upper die  3 . As above, press working operation and transferring operation are readily synchronized only by attaching the die  1  to the press machine without adapting the press machine. 
         [0045]    As illustrated in  FIG. 10 , conventionally, when a die  101  is mounted on a press machine, in order to transmit power to a transfer mechanism  104 , for instance, a rotatable shaft of the press machine (i.e., a position corresponding to a base end of a black arrow) needs to be adapted for output power. Even if a transfer mechanism having an actuator, which is provided separately from the press machine, is employed, for the sake of the synchronization between press working operation and transferring operation, the press machine needs to be adapted for the installation of a sensor for detecting an operating position of the press machine at the position of the press machine corresponding to the base end of the black arrow. 
         [0046]    On the other hand, when the die  1  of the present embodiment is employed, as illustrated in  FIG. 9 , the transfer mechanism  4  is operated in the die  1  by means of a part of power of the press machine to operate the die  1 . 
         [0047]    Moreover, both the clamping mechanism  20  and the feed mechanism  30  convert the rotary movement of the rotatable shaft  13  into the clamp-unclamp operation and the advance-return operation of the holding finger  40  using their cam mechanisms. Therefore, the conversion of operation of the rotatable shaft  13  is made very easy. 
         [0048]    The embodiment of the invention have been described above. However, the invention is not by any means limited to the above-described embodiment, and may be embodied through various modifications without departing from the scope of the invention. 
         [0049]    Modifications of the above embodiment will be described below. In the above embodiment, the die  1  includes the lower die  2  and the upper die  3 . Alternatively, the die  1  may be any die as long as it is a die that is made up of a stationary die and a movable die and that performs plastic deformation work on a workpiece between the stationary die and movable die. For example, the die  1  may be a die in which a movable die reciprocates in a horizontal direction to change an opposing distance between the movable die and a stationary die. 
         [0050]    In the above embodiment, the flat plate cam  21  is used in the clamping mechanism  20 , and the cylindrical groove cam  31  is employed in the feed mechanism  30 . However, the cams of the cam mechanisms are not limited to the flat plate cam  21  and the cylindrical groove cam  31 . For both the clamping mechanism  20  and the feed mechanism  30 , for example, in the case of a plane cam, a plate cam, groove cam, rib cam, or conjugate cam may be used, and in the case of a solid cam, an end cam, cylindrical groove cam, cylindrical rib cam, or drum-shaped rib cam may be employed. 
         [0051]    In the above embodiment, both the clamping mechanism  20  and the feed mechanism  30  include the cam mechanisms. However, the mechanisms  20 ,  30  are not limited to those having the cam mechanisms. One or both of the mechanisms  20 ,  30  may be a link mechanism that does not have a cam mechanism. Furthermore, a link mechanism without the crank mechanism  12  may be used for the conversion of the reciprocation of the rod  11 . For example, a rack and pinion gear may be employed for the conversion of the reciprocation. 
         [0052]    In the above embodiment, the transfer mechanism  4  transfers the workpiece in the horizontal direction, which is perpendicular to a direction of the reciprocation of the upper die  3 . However, the transfer mechanism  4  is not limited to those which transfer the workpiece in the horizontal direction. The transfer mechanism  4  may be any mechanism as long as it is a mechanism which transfers the workpiece in a direction that crosses a direction of the reciprocation of the movable die. In addition, the transfer mechanism  4  may be a mechanism that performs the combination of the transfer of the workpiece in the direction that crosses the direction of the reciprocation of the movable die, and the transfer of the workpiece in the reciprocation direction. 
         [0053]    In the above embodiment, the workpiece is pressed between the lower and upper dies  2 ,  3  of the die  1 . However, the embodiment is not limited to this as long as it is that which performs plastic deformation work on a workpiece between the stationary die and movable die. For example, the invention may be effectively applied to a die for forge processing. 
         [0054]    Additional advantages and modifications will readily occur to those skilled in the art. The invention in its broader terms is therefore not limited to the specific details, representative apparatus, and illustrative examples shown and described.