Abstract:
An upper tool holder apparatus in a press brake includes: a holder main body having an upper tool supporting section for supporting an upper tool a lower portion of the holder main body and further having a mounting; an upper tool clamp supported to the holder main body having an engagement projection at the bottom end of the upper tool clamp which is engaged with a drop-prevention groove provided in the upper tool; a pressing section provided on a lower portion of the upper tool clamp; clamping force applying means for applying a clamping force which clamps the upper tool by pressing an upper portion of the upper tool clamp; clamp operating means for transmitting the clamping force from the clamping force applying means to the upper tool clamp and for releasing the clamping force; and a wedge piece, which is engaged with the drop-prevention groove provided in the upper tool, provided on an upper portion of the engagement projection provided on the lower portion of the upper tool clamp, a force being applied to the wedge piece in a direction where it moves forwards and backwards and it is engaged with the drop-prevention groove. In the construction above, a groove is formed in a front-and-rear direction on a center portion of a right-and-left direction of a lower portion of the mounting plate; and a right-and-left pivoting prevention member which is engaged with the groove is provided on an upper portion of the upper tool clamp.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an upper tool holder apparatus in a press brake, and more specifically relates to an upper tool holder apparatus in a press brake which is capable of easily detaching an upper tool from an upper table in the press brake so as to exchange it with new one. 
     2. Description of Relevant Art 
     A press brake has an upper table (called also as an upper apron) and a lower table (called also as a lower apron). The upper table and the lower table are arranged in an up-and-down direction so as to face each other. One of the upper table and the lower table is suitably driven up and down as a ram. 
     In order that the press brake having the above structure bends a plate-shaped workpiece, a lower tool (die) is mounted to an upper portion of the lower table, and an upper tool (punch) is mounted to a lower portion of the upper table. 
     In the above structure, after the workpiece is located on the die, the upper tool and the lower tool are engaged with each other so that the workpiece can be bent. 
     Incidentally, when a forward end (lower end) of the upper tool provided on the upper table via an upper tool holder apparatus is brought into contact with a V groove formed in the lower tool so that an origin is set in the press brake with a pressure of 2 to 3 t, for example, being applied, the upper tool is broken in the case where a length of the upper tool is short. For this reason, conventionally an operator lifts the upper tool so as to set the origin, and thus this operation is hard. 
     In addition, since the upper tool is exchanged in the press brake because of a difference in forms of bent workpieces, for example, a lot of upper tool holder apparatuses are mounted to the lower portion of the upper table, and the upper tool holder apparatuses support the upper tool to the upper table detachably. 
     The conventional upper tool holder apparatus is constituted so as to mount an upper tool clamp to a holder main body mounted to the lower portion of the upper table via a clamping bolt to be oscillated and firmly fix the upper portion of the upper tool inserted between the upper tool clamp and the holder main body via the upper tool clamp by clamping the clamping bolt. 
     Incidentally, since the above-mentioned conventional upper tool holder apparatus detaches the upper tool from the upper table to exchange it even if the length of the upper tool is short, a lot of the clamping bolts provided in the upper tool holder apparatus should be operated. As a result, this operation is extremely troublesome. Moreover, since a long wedge member is provided in a right-and-left direction between the upper table and lower tool holder apparatus in order to adjust the height of the upper tool, crowning in a longitudinal direction of the upper tool cannot be adjusted fine. 
     SUMMARY OF THE INVENTION 
     The present invention has been achieved with such points in view. It therefore is an object of the present invention to provide an upper tool holder apparatus in a press brake which is capable of simplifying an operation for mounting an upper tool clamp to a holder main body and preventing its rotary movement in a right-and-left direction and easily adjusting a height of an upper tool even if a plurality of especially short upper tool holder apparatuses are used with them being arranged adjacently and simultaneously adjusting crowning. 
     A first aspect of the invention provides an upper tool holder apparatus in a press brake, comprising: a holder main body to be mounted detachably to an upper table in a press brake, the holder main body having an upper tool supporting section for supporting an upper tool a lower portion of the holder main body, the holder main body further having a mounting plate which is pressed and fixed to an upper table at an upper front surface of the holder main body; an upper tool clamp supported to the holder main body so as to be swung on a vicinity of a center portion in an up-and-down direction, the upper tool clamp having an engagement projection at the bottom end of the upper tool clamp, the engagement projection being engaged with a drop-prevention groove provided in the upper tool; a pressing section provided on a lower portion of the upper tool clamp, the pressing section pressing the upper tool against the upper tool supporting section; clamping force applying means for applying a clamping force which clamps the upper tool by pressing an upper portion of the upper tool clamp, the clamping force applying means being provided on the holder main body; clamp operating means for transmitting the clamping force from the clamping force applying means to the upper tool clamp and for releasing the clamping force; and a wedge piece, which is engaged with the drop-prevention groove provided in the upper tool, provided on an upper portion of the engagement projection provided on the lower portion of the upper tool clamp, a force being applied to the wedge piece in a direction where it moves forwards and backwards and it is engaged with the drop-prevention groove, wherein a groove is formed in a front-and-rear direction on a center portion of a right-and-left direction of a lower portion of the mounting plate; and wherein a right-and-left pivoting prevention member which is engaged with the groove is provided on an upper portion of the upper tool clamp. 
     Therefore, the engagement projection provide on the lower portion of the upper tool clamp is engaged with the drop-prevention groove provided in the upper tool so that the upper tool is securely prevented from dropping out of the upper tool holder apparatus. 
     In addition, when the clamping force is transmitted from the clamping force applying means to the upper tool clamp by operating the clamp operating means, the upper tool clamp presses and fixes the upper tool firmly to the upper tool supporting section of the holder main body, and thus the upper tool is fixed securely. 
     Further, since the wedge piece which is engaged with the drop-prevention groove is provided on the upper portion of the engagement projection provided on the lower portion of the upper tool clamp so as to move forward and backward, a clearance between the drop-prevention groove provided in the upper tool and the engagement projection can be reduced, and thus the upper tool is prevented from dropping more securely. 
     The groove is formed in the front-and-rear direction on the center portion of the right-and-left direction of the lower portion of the mounting plate, and the right-and-left pivoting prevention member which is engaged with the groove is provided on the upper portion of the upper tool clamp. As a result, the upper tool clamp is prevented from pivoting in the right-and-left direction. 
     A second aspect of the invention provides an upper tool holder apparatus in a press brake characterized in that the mounting plate and the holder main body are integral with each other. 
     Therefore, the mounting plate and the holder main body are produced integrally so that they are mounted to the upper table easily and more definite accuracy is secured. 
     A third aspect of the invention provides an upper tool holder apparatus in a press brake characterized in that a height adjustment wedge member for adjusting a height by means of a pushing bolt and a pulling bolt is provided between the upper table and the holder main body. 
     Therefore, since the height adjustment wedge member for adjusting a height by means of the pushing bolt and the pulling bolt is provided between the upper table and the holder main body, in the case particularly where short upper tool holder apparatuses are used so as to be adjacent to each other, the respective height adjustment wedge members adjust heights from a front side by means of the pushing bolts and the pulling bolts and simultaneously adjust crowning. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side sectional view of an upper tool holder apparatus of the present invention showing an unclamped state. 
     FIG. 2 is a front view of FIG.  1 . 
     FIG. 3 is an enlarged view in a middle portion of the upper tool holder apparatus of the present invention shown in FIG.  1 . 
     FIG. 4 is a side sectional view of the upper tool holder apparatus of the present invention showing a clamped state. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     There will be detailed below an embodiment of the present invention with reference to the drawings. 
     As shown in FIGS. 1 and 2, an upper tool holder apparatus  1  according to the present embodiment is mounted detachably to a lower portion of an upper table  3  in a press brake (the overall structure is not shown). A plurality of the upper tool holder apparatuses  1  are mounted to the lower portion of the upper table  3  with suitable intervals in a right-and-left direction. 
     Namely, an upper tool  5  in the press brake is such as one upper tool which is long in a right-and-left direction (direction vertical to a sheet surface in FIG.  1  and the right-and-left direction in FIG. 2) and plural divided-type upper tools with different lengths which are used by suitably combining them. The plural upper tool holder apparatuses  1  are mounted to the upper table  3  with suitable intervals so as to cope with both the above cases. 
     As is clear from FIG. 1, the upper tool holder apparatus  1  has a holder main body  7 , an upper tool clamp  11 , clamping force applying means  13  and clamp operating means  15 . The holder main body  7  is mounted to the upper table  3  detachably. The upper tool clamp  11  can freely press and fix an upper portion  5 U of the upper tool  5  to an upper tool supporting section  9  provided integrally with a lower portion of the holder main body  7 . The clamping force applying means  13  applies a clamping force to the upper tool clamp  11 . The clamp operating means  15  can transmit the clamping force from the clamping force applying means  13  to the upper tool clamp  11  and release the clamping force. 
     More specifically, the holder main body  7  is formed so that the thin upper tool supporting section  9  is provided integrally with a lower portion of a thick block section  7 B in a front-and-rear direction. A mounting plate  19  which is projected in an upper direction is produced integrally with a front surface (left side surface in FIG. 1) of the block section  7 B of the holder main body  7 . 
     An upper projected section of the mounting plate  19  is brought into contact with a front lower portion of the upper table  3 , and a clamping jaw  23  is tightened by a clamping bolt  21  threaded into the upper table  3  so that the upper projected section of the mounting plate  19  is pressed and fixed to the upper table  3 . As a result, the holder main body  7  can be mounted to the upper table  3 . 
     In order to adjust an up-and-down position (height position) of the holder main body  7 , a wedge member  25  intervenes between an upper surface of the holder main body  7  and a lower surface of the upper table  3 . Namely, the wedge member  25  is provided on the upper surface of the holder main body  7  by a pin  27  and is composed of a lower wedge member  25 A and an upper wedge member  25 B. The lower wedge member  25 A is slanted high from a left side to a right side in FIG.  1 . The upper wedge member  25 B, which is slanted low from the right side to the left side, slides between the lower wedge member  25 A and the upper table  3  in the right-and-left direction in FIG. 1 by means of a pulling bolt  29  and plural pushing bolts  31  which is shown in FIG.  2  and FIG.  4 . 
     More specifically, the upper wedge member  25 B slides in the left direction in FIG. 1 by means of the pulling bolt  29  when the pulling bolt  29  is screwedly tied up. On the other hand, the upper wedge member  25 B slides in the right direction in FIG. 1 by means of the plural pushing bolts  31  as shown in FIG.  4 . When the pulling bolt  29  is screwedly tied up in the mounting plate  19 , so that the upper wedge member  25 B slides in the right direction in FIG. 4 as shown by two dotted phantom line, so as to move the mounting plate  19  downwardly in FIG.  4  through the lower wedge member  25 A. 
     Therefore, the pulling bolt  29  and the pushing bolts  31  are operated so that the upper wedge member  25 B slides with respect to the lower wedge member  25 A in the right-and-left direction in FIG.  1 . As a result, the height position of the holder main body  7  can be adjusted from the front side, and the height position of the upper tool  5  can be adjusted. Further, the plural upper tool holder apparatuses  1  are mounted so as to adjacent to the upper table  1  so that crowning of the plural upper tools  5  can be adjusted individually from the front side. 
     The upper tool clamp  11  is composed of a plate-shaped member having a width approximately equal to a width of the right-and-left direction of the holder main body  7 . In order to press and fix the upper section  5 U of the upper tool  5  between the upper tool supporting section  9  and the holder main body  7 , the upper tool clamp  11  is supported to the holder main body  7  so as to be oscillated. 
     More specifically, a plurality of through holes  11 H are provided in a vicinity of the center portion of the up-and-down direction of the upper tool clamp  11 , and the upper tool clamp  11  is supported to a head section of a mounting bolt  33  inserted through the through holes  11 H and horizontally fitted and fixed into the upper tool supporting section  9  so as to be oscillated. Moreover, a coil spring  35  is elastically mounted between the upper tool supporting section  9  and the upper tool clamp  11  so as to separate them from each other. 
     Here, in order to oscillate the upper tool clamp  11  smoothly, a contact portion between the head section of the mounting bolt  39  and the through holes  11 H is formed into a spherical contact surface. 
     An engagement projection  11 P, which is engaged with a slip-prevention groove  5 G formed in an upper portion of the upper tool  5  in the right-and-left direction, is formed on a lower end section of the upper tool clamp  11  so as to be projected to a direction of the upper tool supporting section  9 . A pressing section  37 , which contacts with a slanted surface  5 S of the upper section  5 U of the upper tool  5  and presses the upper tool  5  against the upper tool supporting section  9 , is provided on a portion of the upper tool clamp  11  which is slightly upper than the engagement projection  11 P. 
     The pressing section  37  is formed into a shape obtained by machining a portion of a peripheral surface of a column into a flat surface. The pressing section  37  is mounted to the lower portion of the upper tool clamp  11  via a plurality of screws  39  so as to slightly pivot. 
     In addition, a plurality of wedge pieces  41 , which can be engaged with the slip-prevention groove  5 G of the upper tool  5 , are provided on the upper portion of the engagement projection  11 P between the pressing section  37  and the engagement projection  11 P so as to move forward and backward. A force is always applied to the wedge pieces  41  to a direction where they are engaged with the drop-prevention groove  5 G by the function of an elastic member  43  such as a coil spring mounted between the upper tool clamp  11  and the wedge pieces  41 . 
     The movement of the wedge piece  41  due to the applied force is regulated by bringing one portion of the wedge piece  41  into contact with one portion of the pressing member  37 , and a slanted surface  41 S is formed on a forward end upper surface of the wedge piece  41  so that the wedge piece  41  can be easily engaged with and removed from the drop-prevention groove  5 G. 
     The clamping force applying means  13 , which applies a clamping force, for pressing and fixing the upper tool  5  to the upper tool supporting section  9  by means of the pressing section  37  provided on the lower portion of the upper tool clamp  11 , to the upper tool clamp  11 , is mounted into a hole  7 H in the front-and-rear direction provided in the block section  7 B of the holder main body  7 . 
     More specifically, as shown in FIG. 3 which shows an enlarged view in a middle portion of the upper tool holder apparatus (especially around the clamping force applying means  13  and the clamp operating means  15 ), a projection pin  45  is provided in the hole  7 H in a left direction in FIG. 3, and a projected section  45 T of the projection pin  45  is fitted into another projection pin  49  via a powerful elastic member  47  such as a belleville spring. Moreover, a ring nut  51  is threaded into a projected section  49 T of the projection pin  49 . 
     The clamp operating means  15 , which transmits the clamping force from the clamping force applying means  13  to the upper tool clamp  11  and releases the clamping force, is provided on an upper side of the upper tool clamp  11 . 
     More specifically, the clamp operating means  15  is provided on the upper portion of the upper tool clamp  11  so as to pivot. Moreover, a pressing screw  53 , as a pressing control member which contacts with and removes from the projected section  49 T of the projection pin  49 , is threaded into the upper portion of the upper tool clamp  11  so as to move forward and backward. A forward end of the pressing screw  53  is brought into contact with the projected section  49 T of the projection pin  49 . 
     Therefore, when the pressing screw  53  is pivoted so as to be loosened with respect to the upper tool clamp  11 , the pressing screw  53  is removed from the projection pin  49 . On the contrary, when the pressing screw  53  is tightened, the pressing screw  53  is slightly brought into contact with the projected section  49 T of the projection pin  49 . Furthermore, when the pressing screw  53  is further tightened strongly, the pressing screw  53  strongly presses the projected section  49 T of the projection pin  49  so as to compress the elastic member  47 . As a result, a regenerative force of the elastic member  47  is applied as a reaction force to the pressing screw  53 . 
     The pressing screw  53  is provided with an engagement hole  53 H, and one end of an operation lever, not shown, is engaged with the engagement hole  53 H. 
     In addition, as shown in detail in FIGS. 1 through 3, a groove  55  is formed in the front-and-rear direction on an approximately center portion of the right-and-left direction at the lower section of the mounting plate  19 , and a right-and-left pivoting prevention member  57  such as a pin, which is engaged with the groove  55 , is provided on the upper portion of the upper tool clamp  11 . 
     In the above structure, as the upper tool  5  is shown by an imaginary line, when the upper tool  5  is clamped between the upper tool supporting section  9  of the holder main body  7  and the upper tool clamp  11 , the operation lever is engaged with the engagement hole  53 H of the pressing screw  53  and is pivoted so that the pressing screw  53  as the pressing control member is tightened. As a result, the elastic member  47  in the clamping force applying means  13  is further compressed. 
     Therefore, the regenerative force of the elastic member  47  is increased, and the upper tool clamp  11  is pivoted in a counterclockwise direction in FIG. 1 by a reaction force of the regenerative force, namely, in the clamped state shown in FIG.  4 . As a result, the upper tool clamp  11  presses and fixes the upper tool  5  more strongly. 
     On the contrary, when the operation lever is pivoted so that the pressing screw  53  is slightly loosened, the pressing screw  53  is slightly brought into contact with the projected section  49 T of the projection pin  49  of the clamping force applying means  13 , and the pressed fixing of the upper tool  5  by means of the upper tool clamp  11  is released. As a result, the engagement projection  11 P of the upper tool clamp  11  is engaged with the drop-prevention groove  5 G, and thus the upper tool  5  is supported movably in the longitudinal direction (right-and-left direction) so as to be in the unclamped state shown in FIG.  1 . 
     When the upper tool  5  is clamped and unclamped by the upper tool holder apparatus  1 , the upper tool clamp  11  oscillates in the groove  55  in the front-and-rear direction on the head section of the mounting bolt  33 . However, the right-and-left pivoting prevention member  57  can prevent the pivoting of the upper tool clamp  11  in the right-and-left direction. 
     When the engagement projection  11 P provided on the lower portion of the upper tool clamp  11  is engaged with the drop-prevention groove  5 G provided on the upper tool  5 , the upper tool  5  can be prevented securely from dropping out of the upper tool holder apparatus  1 . 
     In addition, when the clamping force by the clamping force applying means  13  is transmitted to the upper tool clamp  11  by operating the clamp operating means  15 , the upper tool clamp  11  presses and fixes the upper tool  5  to the upper tool supporting section  9  of the holder main body  7  firmly, and thus the upper tool  5  can be fixed securely. 
     Furthermore, since the wedge piece  41 , which can be engaged with the drop-prevention groove  5 G provided in the upper tool  5 , is provided on the upper portion of the engagement projection  11 P provided on the lower portion of the upper tool clamp  11  so as to move forward and backward, a clearance between the drop-prevention groove  5 G provided in the upper tool  5  and the engagement projection  11 P can be reduced. As a result, the dropping of the upper tool  5  can be prevented securely. 
     When the unclamped state shown in FIG. 1 is changed into the clamped state  17  shown in FIG. 4, a gap between the upper surface of the upper tool  5  and the lower surface of the upper tool supporting section  9  becomes zero. In this state the origin of the lower tool and the upper tool  5  is set and they are aligned so that the setting of the origin and alignment can be executed simultaneously and accurately without requiring additional step of alignment and without breaking the upper tool  5 . 
     In addition, when the holder main body  7  and the mounting plate  19  are produced integrally, they can be mounted to the upper table  3  easily, and more definite accuracy can be secured. Since the height adjusting wedge member  25  for adjusting a height by means of the pushing bolt  31  and the pulling bolt  29  is provided between the upper table  3  and the holder main body  7 , in the case particularly where the upper tool holder apparatuses  1  are used with them being arranged adjacently to each other, the height of the upper wedge member  25 B is adjusted from the front side with respect to the lower wedge member  25 A by the pushing bolt  31  and the pulling bolt  29 , and simultaneously crowning can be also adjusted. The length of the upper tool holder apparatus  1  in the right-and-left direction may be 25, 35, 40 and 50 mm, for example, and the upper tool holder apparatuses  1  with these lengths can be used individually, or a plurality of them are used with intervals, or they are used adjacently to each other. At this time, the one upper tool  5  are used or divided upper tools  5  are used. 
     The entire contents of Japanese Patent Application P10-239155 (filed Aug. 25, 1998) are incorporated herein by reference. 
     Although the invention has been described above by reference to certain embodiments of the invention, the invention is not limited to the embodiments described above. Modifications and variations of the embodiments described above will occur to those skilled in the art, in light of the above teachings. The scope of the invention is defined with reference to the following claims.