Abstract:
A punch holder apparatus includes: a punch holder formed with a punch mounting hole and with an inspection hole in a direction perpendicular to a longitudinal direction of the punch holder; an engagement piece to be mounted in the inspection hole; a lock piece formed with a receiving allowable concave section to receive the engagement piece; and pressurizing means for pressurizing the lock piece so that an engagement piece pushing-out holding section provided to the lock piece is normally located in a position corresponding to the engagement piece. In the above construction, the lock piece is provided so as to be capable of moving in a direction parallel to the longitudinal direction of the punch holder. Furthermore, the receiving allowable concave section receives the engagement piece which is moved in the direction perpendicular to the longitudinal direction of the punch holder.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a punch holder apparatus which a punch chip is mounted to and is used for a punching process. 
     2. Description of Relevant Art 
     In the relevant art, a conventional punch holder apparatus of a burring tools contains a lot of members including a punch chip. When a thickness of a workpiece to be burred is changed by changing to another material workpiece, manually changing operation of the punch chip is required. Therefore, since the punch holder apparatus of a burring tools contains a lot of members and the structure of the punch holder apparatus is complex, the manually changing operation of the punch chip is very tedious and hard. 
     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 a punch holder apparatus where a punch chip can be changed so as to be mounted to and removed from a punch holder with one step and one action. 
     A first aspect of the present invention provides a punch holder apparatus, comprising: a punch holder formed with a punch mounting hole in a longitudinal direction of the punch holder, the punch holder further formed with an inspection hole in a direction perpendicular to the longitudinal direction of the punch holder; an engagement piece to be mounted in the inspection hole, the engagement piece being able to move in the inspection hole so as to locate on an inner circumferential surface of the punch mounting hole; a lock piece formed with a receiving allowable concave section to receive the engagement piece, the lock piece being provided so as to be capable of moving in a direction parallel to the longitudinal direction of the punch holder, the receiving allowable concave section receiving the engagement piece which is moved in the direction perpendicular to the longitudinal direction of the punch holder; and pressurizing means for pressurizing the lock piece so that an engagement piece pushing-out holding section provided to the lock piece is normally located in a position corresponding to the engagement piece. 
     Therefore, in order to mount a punch chip to the punch mounting hole formed in the punch holder, when the lock piece is pushed from a downward side, for example, the lock piece moves upward, for example, against an applied force of the pressurizing means, and the engagement piece pushing-out holding section provided to the lock piece slips out of the engagement piece. Then, the receiving allowable concave section comes to a position corresponding to the engagement piece so that the engagement piece is fitted into the receiving allowable concave section, and the punch chip is inserted into the punch holder. After the insertion, when the state that the lock piece is pushed is released, the engagement piece pushing-out holding section moves to the position to the engagement piece by means of the applied force of the pressurizing means so as to pressurize or press the engagement piece, and the punch chip is engaged with the punch holder. 
     In the case where the punch chip is removed from the punch mounting hole, when the lock piece is pushed from a downward side, for example, the lock piece moves upward, for example, against the applied force of the pressurizing means so that the engagement piece pushing-out holding section slips out of the engagement piece. In this state the punch chip is pulled, for example so that the punch chip comes out of the punch holder. 
     In such a manner, the punch chip is easily mounted to and removed from the punch mounting hole of the punch holder with one step. 
     A second aspect of the invention, as it depends from the first aspect, provides a punch holder apparatus wherein the inspection hole from which the state of the engagement piece can be checked in such a manner that the inspection hole opens to an outer circumferential surface of the punch holder. 
     Therefore, since the punch holder has the inspection hole, the state of the engagement piece can be easily checked from the inspection hole. 
     A third aspect of the invention, as it depends from the first aspect or the second aspect, provides a punch holder apparatus wherein the lock piece has a stopper section which always stops in a constant position so that the engagement piece is automatically fitted into the receiving allowable concave section. 
     Therefore, since the stopper section is provided to the lock piece, the stopper section always stops in a constant position, and the engagement piece is automatically fitted into the receiving allowable concave section. 
    
    
     BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS 
     The above and further objects and novel features of the present invention will more fully appear from the following detailed description when the same is read in conjunction with the accompanying drawings, in which: 
     FIG. 1 is a front sectional view of a punch tool showing an upper tool and a lower tool provided with a punch holder apparatus according to a second embodiment of the present invention; 
     FIG. 2 is a front sectional view of a punch chip; 
     FIG. 3 is a front sectional view of a punch holder; 
     FIG. 4 is a bottom view of FIG. 3; 
     FIG. 5 is a drawing for explaining an operation; 
     FIG. 6 is a drawing for explaining an operation; and 
     FIG. 7 is a front sectional view of a burring tool showing an upper tool and a lower tool according to a first embodiment. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     There will be detailed below the preferred embodiments of the present invention with reference to the accompanying drawings. Like members are designated by like reference characters. 
     As shown in FIG. 7, a punch holder apparatus for a burring tool  101  to burr a workpiece upward according to a first embodiment has an upper tool  103  and a lower tool  105 . The upper tool  103  has a punch holder  107  which is extended in a up-and-down direction, and a punch mounting hole  109  is formed at a forward end (lower end) of the punch holder  107 . 
     In a state that a punch chip  113  having urethane rubber  111  is mounted to a punch supporting member  115  from a lower side, an upper portion of the punch chip  113  is mounted to the punch mounting hole  109  and is fixed by a plurality of bolts  117  with the punch supporting member  115  being brought into contact with the lower end of the punch holder  107 . 
     Meanwhile, the lower tool  105  has a die base  119 , and in a state that urethane rubber  123  is mounted into a groove  121  formed in the die base  119 , an ejector  125  is provided on the die base  119  so as to be mounted to the die base  119  by a through bolt  127  from the lower side. Furthermore, an ejector pin  129  is mounted from an upper side to an approximately center portion of the die base  119  and the ejector  125 . The ejector pin  129  is mounted to the die base  119  by a bolt  131 . 
     According to the above structure, a work W is placed on the ejector  125  and the punch tool  103  is lowered to the die tool  105  so that the urethane rubber  111  pressurizes the work W. Moreover, the urethane rubber  121  is deflected and the ejector  125  descends so that the ejector pin  129  is projected from the ejector  125 . As a result, the work W is subject to upward burring process by co-operation of the punch chip  113  and the ejector pin  129 . 
     In this connection, in the above-mentioned punch tool  103  according to the first embodiment, since the punch chip  113  is fixed to the punch holder  107  by the plural bolts  117  via the punch supporting member  115 , in order to remove and mount the punch chip  113  from/to the punch holder  107 , the bolts  117  should be loosened and tightened. As a result, the punch chip can be changed so as to be mounted to and removed from a punch holder with small amount actions. 
     There will be detailed below a second embodiment of the present invention where the first embodiment is modified with reference to FIGS. 1 through 6. Especially the object of the second embodiment is to provide a punch holder apparatus where a punch chip can be changed so as to be mounted to and removed from a punch holder with one step, one action or one shot. 
     As shown in FIG. 1, a burring tool  1 , for example, has an upper tool  3  and a lower tool  5 . The upper tool  3  has a punch holder  7  which is extended in an up-and-down direction, and a punch mounting hole  9  is formed at a forward end (lower end) of the punch holder  7 . A punch chip  11  is mounted to and removed from the punch mounting hole  9  with one step. 
     Meanwhile, the lower tool  5  has a die base  13 , and a plurality of grooves  15  are formed in the die base  13 . Urethane rubber  17  is fitted into the grooves  15  with a force being applied to the urethane rubber  17  upward. An ejector  19  is provided on the urethane rubber  17 . An ejector pin  21  is mounted to an approximately center portion of the ejector  19  and the die base  13  and is fitted into the die base  13  by a screw  23  provided on a lower end portion of the ejector pin  21 . 
     According to the above structure, a work, for example, is placed on the ejector  19  and the punch holder  7  is lowered. Then, the work is subject to an upward burring process by co-operation of the punch chip  11  and the ejector pin  21 . 
     As shown in detail in FIG. 2, an R-shaped groove  25  is formed on an outer circumference of the punch chip  11 , and a collar  27  and urethane rubber  29  are provided on an outer circumference of a lower portion of the punch chip  11 . 
     As shown in FIGS. 3 and 4, a hole  31  into which a finger of an operator can be inserted is formed at a lower portion of the punch mounting hole  9  so as to be interconnected therewith in the punch holder  7 . A hole  33  which is extended in an up-and-down direction is formed on a right portion of the punch holder  7  in FIG. 3, and a hole  35 , which pierces through in a direction intersecting perpendicularly to the hole  33  (right-and-left direction in FIG.  3 ), is formed. A left end of the hole  35  in FIG. 3 is interconnected with the punch mounting hole  9 . 
     A steel ball  37  as one example of an engagement piece is fitted into the hole  35 . Moreover, a spring  39  as one example of pressurizing means is mounted to an upper portion in the hole  33 , and a pin  45  as one example as a lock piece, which has a receiving allowable concave section  41  forming a circumferential recess  41   a  for the steel ball  37  and an engagement piece pushing-out holding section  43 , is mounted into the hole  33 . Furthermore, a forward end (upper end) of the pin  45  has a stopper section  47 . Moreover, a set screw  51  where a hole  49  pierces through its center portion is fitted into a lower end of the hole  33  so that the pin  45  does not slip outside. A forward end (right end) of the hole  35  is opened so as to become an inspection hole  53 . 
     According to the above structure, FIG. 3 shows the state before the punch chip is mounted, FIG. 5 shows the state that the punch chip is being mounted, and FIG. 6 shows the state that the mounting of the punch chip is completed. In the case where the punch chip  11  is mounted into the punch mounting hole  9  of the punch holder  7 , as shown in FIG. 5, when an operator holds a bar  55  and inserts the bar  55  into the hole  49  and pushes the pin  45  upward (a direction of an arrow P). As a result, the pin  45  moves upward against an applied force of the spring  39 , and the stopper section  47  bumps against the forward end of the hole  33  so that the receiving allowable concave section  41  is moved to a position corresponding to the steel ball  37 . For this reason, as represented by an arrow T, the steel ball  37  is relieved into the receiving allowable concave section (relief groove)  41  so that the punch chip  11  can be inserted into the punch mounting hole  9 . 
     When the bar  55  is released after the punch chip  11  is inserted into the punch mounting hole  9 , the pin  45  moves downward (a direction of an arrow Q) by means of the applied force of the spring  39 , and the steel ball  37  is pushed by the engagement piece pushing-out holding section  43  as represented by an arrow S in FIG.  6 . As a result, the punch chip  11  is fitted into the R-shaped groove  25  so that the mounting is completed. 
     In the case where the punch chip  11  is removed from the punch mounting hole  9 , when the bar  55  is inserted into the hole  49  of the set screw  51  and the pin  45  is pushed, the pin  45  moves upward against the applied force of the spring  39  so that the engagement piece pushing-out holding section  43  is removed from the steel ball  37 . In this state, the punch chip  11  is pulled downward so that the punch chip  11  comes out of the punch mounting hole  9 . 
     In such a manner, the punch chip  11  can be easily mounted to and removed from the punch mounting hole  9  of the punch holder  7  with one step. 
     Since the punch holder  7  has the hole  33 , namely, the inspection hole  53 , the state of the steel ball  37  can be easily checked from the inspection hole  53 . Moreover, since the stopper section  47  is provided to the forward end of the pin  45 , the stopper section  47  bumps against the forward end of the hole  33  and stops so that the steel ball  37  can be allowed to come into the receiving allowable concave section  41  automatically. 
     Here, the present invention is not limited to the above-mentioned embodiment, so the present invention can be practiced in another form by suitable modification. 
     The entire contents of Japanese Patent Application P10-220780 (filed Aug. 4, 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 descried 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.