Die holder mounting structure

Abstract: A die holder mounting structure that improves the accuracy of the mounting of a die holder and allows for simple and quick attachment/removal of the die holder. Pin insertion holes 25, 26 adjustable relative to each other are arranged on a die holder 6 mounted on an alignment plate 7 of the lower turret 2 and that alignment plate 7. A mounting pins 11 are arranged inserted from the die holder 6 side through both pin insertion holes 25, 26. This mounting pin 11 is capable of increasing and decreasing in diameter while inserted in the pin insertion holes 25, 26. The mounting pin 11 is charged with a pressure medium 22 such as oil or the like and this diameter increase is carried out by the pressurization of the pressure medium 22 by the screwing of a pressure application screw 23 or the like.

Description: TECHNICAL FIELD The present invention relates to a die holder mounting structure for a turret punch press. BACKGROUND ART On a conventional turret punch press, a die is arranged on the lower turret via a die holder and dies are exchanged at each die holder. The mounting of the die holder on the lower turret is carried out by the coupling of one end to a pin projecting from the lower turret and fixing the other end with a bolt. Document DE-A-3327676 discloses an arrangement corresponding to the preamble of claim 1 Having a conventional arrangement as described above where the die holder is fixed by a bolt necessitates space in the inner diameter of the bolt hole and because of this, there are limits to the accuracy of the mounting of the die holder on the lower turret. As a result, core dis-alignment between the die and punch is generated and it is necessary to arrange enough clearance between the die and punch in order to be able to absorb this core dis-alignment. However, when the clearance between the die and punch increases, the barb generated on the reverse side of the work punch hole exponentially increases and clean punch processing becomes difficult. Apart from the accuracy of the mounting of the die holder, rigidity and heat deformation of the frame as well as core dis-alignment of the upper and lower turrets have been posited as reasons for the generation of core dis-alignment between the die and punch and in order to limit the generation of barb, it is necessary to generally improve these. However, accuracy of the mounting of the die holder is a large cause of core dis-alignment. SUMMARY OF THE INVENTION In order to solve the above problems, it is an object of the present invention to propose a die holder mounting structure for a turret punch press that improves the accuracy of the mounting of the die holder. In order to achieve the above object, the die holder mounting structure of the present invention is arranged with corresponding pin insertion holes on a die holder mounted on a lower turret and on that lower turret, is also arranged with a mounting pin that is inserted from the die holder side through the pin insertion holes, and which mainting pin is capable of increasing or decreasing its diameter when inserted in the pin insertion hole. Accordingly, removal of the mounting pin is performed when in the decreased diameter state and by increasing the diameter of the mounting pin after insertion, the mounting pin is in a pressurized state in the pin insertion hole. As a result, there is no space between the mounting pin and pin insertion hole and the die holder can be mounted with increased accuracy. Moreover, removal of the mounting pin is simple as it is removed when there is a high degree of space in the pin insertion hole. The lower turret may have a turret main body and an alignment plate attached to the upper surface of the turret main body so as to be position-adjustable and upon which is loaded the die holder. In this example, the aforementioned pin insertion hole of the lower turret is arranged in the alignment plate. Due to the adjustment of that mounting position, the alignment plate is able to adjust the core dis-alignment between the die and punch arising from the core dis-alignment of the upper and lower turrets independently for each die. Due to the insertion of a mounting pin through the alignment plate and die holder and the diameter increase of this mounting pin, the alignment plate and die holder may be fixed in the radial direction and the die holder may be fixed in a highly accurate position horizontally with respect to the alignment plate. Furthermore, the aforementioned mounting pin is arranged with a non-circular head, the opening of the pin insertion hole of the die holder is arranged with a counter-bore that fits with that head part and a stepped part may be arranged on that upper edge of that counter-bore and on which rests that head part by rotating it by a predetermined angle with respect to the positioning hole of the mounting pin. In the above structure, normally the die holder is fixed by the insertion of the mounting pin in the pin insertion hole so that the head of the mounting pin fits with the counter-bore part and whenever the die is to be exchanged, after removing the mounting pin to a raised state, the mounting pin can be held in the raised state by the head part by slightly rotating it. As a result, by this simple arrangement of a head part, the mounting pin can be held in a raised state. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1A is a plan view of the die holder mounting structure of a first embodiment of the present invention, Figure 1B is a fractured side view of the same and Figures 1C and 1D are an enlarged side view and enlarged plan view of the mounting pin respectively. Figure 2A is a plan view of the mounting pin of the die holder mounting structure of the present invention in the raised held state and Figure 2B is a sectional view showing the dis-alignment in the axis of rotation between the die holder and alignment plate. Figure 3A is a sectional view showing a schematic drawing of the mounting pin of the die holder mounting structure of the present invention, Figure 3B is a sectional view showing a schematic drawing of another embodiment of the mounting pin and of the die holder mounting structure of the present invention and Figure 3C is a side view of the same. Figure 4 is a schematic perspective view showing the turret part of a turret punch press utilizing the die holder mounting structure of the present invention. Figure 5 is a fractured plan view showing the schematic structure of a turret punch press. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A first embodiment of the present invention will be described based on the drawings. As shown in the schematic drawing in Figure 4, a punch holder 4 which freely vertically moves is fitted in each punch fitting hole 3 arranged around the periphery of an upper turret 1. The punch holder 4 is a forcibly raised type incorporated in the punch (not shown in the drawing) and has a T-shaped head part coupled to a guide board (not shown in the drawing) and ram. A die holder 6 which holds either one or a plurality of die 5 (only one is shown in the drawing) is positioned on the upper surface of a lower turret 2 via an alignment plate 7. The alignment plate 7 is one part of the lower turret 2 and is mounted on the lower turret main body 2a by a plurality of bolts so that minute mounting position adjustments may be made. The inner end of the die holder 6 in the turret radial direction is fixed by an inner end fixing pin 10 and the outer end is fixed by a mounting pin 11. As shown in Figure 1, the plane of the die holder 6 is formed as an approximate fan shape with round die fitting holes 13, 13 that incorporate the die 5 arranged in two separate places in the turret radial direction. A hole 14 for slag ejection is arranged in the base of the die fitting hole 13. A die 5 is fitted in the die fitting hole 13, rests upon the base formed by the step around the hole 14 and is fixed in place by a stop screw (not shown in the drawings) in a screw hole bored in the side of the die holder 6. The alignment plate 7 is plate shaped having a flat shape similar to the die holder 6 and is arranged with a hole 16 continuous with the hole 14 of the die holder 6. An inside coupling arm 17 extends from the center of the narrow end of the die holder 6, which forms the turret inner diameter side and a U-shaped notch 18 is arranged in that end. The opened end of the notch 18 is formed as a taper shape. The notch 18 fits into the shaft of the aforementioned inner end fixing pin 10 and the head 10a being larger in diameter than the inner end fixing pin 10 couples with upper surface of the inside coupling arm 17. Then shaft tip of the inner end fixing pin 10 is a male screw and is held in place from the lower side by a nut passing through the alignment plate 7. Two pin insertion holes 25, 26 which may be adjusted relative to each other are arranged in the outer diameter side end of the die holder 6 and alignment plate 7 respectively. A mounting pin 11 is fitted through these pin insertion holes 25, 26. A counter-bore 27 into which fits the head 11a of the mounting pin 11 is formed in the upper surface open part of the pin insertion hole 25 of the die holder so that the plan shape that is open to the die holder outer diameter is a U-shaped notch. The base of that U-shaped counter bore 27 is formed as a vertical straight line part 27a with respect to the turret radial direction and moreover, a step 27b comprising a shallow notch is formed along this straight line part 27a. The mounting pin 11 is formed as a headed pin having a head 11a of which the periphery is wide as shown in Figures 1C and 1D and as described later, the shaft 11b is able to increase and decrease in diameter by a predetermined operation. Furthermore, the head 11a of the mounting pin 11 is formed as a non-circular shape having two cut-away parts being straight lines a, b. The aforementioned two straight lines a, b are angled away from being in a parallel state with each other by a predetermined angle. One of the straight lines a is barb with the straight line 27a on the counter-bore 27 of the die holder 6. A table 31 for loading and guiding the work is arranged on the upper surface of the die holder 6 as a partial table 31A, 31B divided in two in the turret radial direction. The inner diameter side partial table 31A is fixed directly to the upper surface of the die holder 6 by a bolt or the like (not shown in the drawings). The outer diameter side partial table 31B is mounted on the head 11a of the mounting pin 11 via a thick circular spacer 32. The spacer 32 is mounted on the underside of the partial table 31B by a mounting screw 33 which is inserted from the underside and moreover is mounted on the head 11a by a mounting screw 34 which passes through the head 11A from below. Furthermore, a free bearing 29 is arranged on the upper surface of the partial table 31B in a state where it is buried in the bearing case concentric with the mounting pin 11. Figure 3A shows a fluid type increase-decrease means 20 that increases or decreases the diameter of the mounting pin 11. The shaft 11b of the mounting pin 11 comprises a cylindrical filling chamber 20a near the outer periphery as shown in the drawing and the periphery of the filling chamber 20a forms an outer sleeve 11ba. A female screw part 21 which is open to the outer diameter surface of the head 11a is arranged in the filling chamber 20a and a pressure medium 22 comprising a liquid such as oil or the like is present in the filling chamber 20a. A pressure application screw 23 is screwed into the female screw part 21 and by screwing the pressure application screw 23, the pressure medium 22 is pressurized and the sleeve 11ba is pushed out from the inner part and the shaft 11b of the mounting pin 11 is increased in diameter. When the pressure application screw 23 is loosened, the shaft 11b diameter decreases due to the elasticity of sleeve 11ba. The pressure application screw 23 is unremovable due to a stopper screw 40 (Figure 1C) that is screwed into a screw hole arranged in the inner diameter surface of the female screw part 21. It should be noted that the mounting pin 11 may be so arranged that the shaft 11b is increased and decreased in diameter by a mechanical increase-decrease means 24 as shown in Figure 3B. The increase-decrease means 24 of the same drawing comprises a mounting pin 11 of 2 members being a sleeve 11A and a core member 11B both with a head attached and the sleeve 11A has a cross-sectional taper shape so that the inner diameter surface becomes smaller in diameter towards the tip. The core member 11B is comprised as tapered pin shape that fits with the inner diameter surface of the sleeve 11A and moreover, comprises a screw 28a close to the basal end and screws into the female screw 28b in the base of the sleeve 11A. Expanding slots 41 extending in the axial direction from the tip to the head area are arranged in a plurality of places in the peripheral direction in the sleeve 11A and approximately circular spreading parts 41a are arranged in the upper end of the expanding slots 41. Heads 11Aa,11Ba of the sleeve 11A and core member 11B are both non-circular and may be rotated relative to each other by a tool. When this mounting pin 11 is used, the sleeve 11A is pushed outwards from the inner surface by the screwing of the core member 11B into the sleeve 11A thus increasing the diameter of the shift 11b. Furthermore, when the screwed state of the core member 11B is loosened with respect to the sleeve 11A, the sleeve 11A reverts to the original diameter due to its elasticity and decreases in diameter. It should be noted that the sleeve 11A easily increases in diameter due to the formation of the expanding slots 41. Furthermore, as spreading parts 41a are formed in the upper end of the expanding slots 41, cracks from the top end of the expanding slots 41 where stress easily concentrates are prevented even after repeated diameter increases and decreases. Next, the die exchange operation on the above described die holder mounting structure will be described. When the die 5 is to be exchanged, the die holder 6 is removed from the alignment plate 7 of the lower turret 2 and exchanged for a die 5 from a die holder 6 on a separate device. The die holder 6 with the exchanged die 5 is then re-attached to the alignment plate 7 of the lower turret 2. When this attachment is carried out, the die holder 6 couples the U-shaped notch 18 to the inner end fixing pin 10 of the alignment plate 7 and after this, the mounting pin 11 is inserted through the die holder 6 and the pin insertion holes 25, 26 of the alignment plate 7. After insertion into the pin insertion holes 25, 26, the shaft 11b of the mounting pin 11 is expanded by screwing the pressure application screw 23. Accordingly, the shaft 11b exerts pressure on the inner diameter surface of the pin insertion holes 25, 26 of the die holder 6 and alignment plate 7, is strongly fixed to the die holder 6 and alignment plate 7 and ensures immobility in the axial direction. Furthermore, as the mounting pin 11 is increased in diameter and is pressurized, the accuracy of the positioning of the die holder 6 with respect to the alignment plate 7 is high and core dis-alignment between the die 5 and punch is reduced. As a result, the clearance between the die 5 and the punch can be reduced, barb of the punch processed products reduced and the quality of products improved. As insertion and removal of the mounting pin 11 with respect to the pin insertion holes 25, 26 is carried out with the mounting pin 11 in the diameter decreased state, a large amount of space is generated in the inner part of the pin insertion holes 25, 26 and removal is simplified. This die holder mounting structure enables simple and quick attachment and removal of the die holder 6 and moreover, ensures improved accuracy. Furthermore, when the die holder is to be removed, the mounting pin 11 is simply removed from the pin insertion hole 26 of the alignment plate 7 and left in a raised state while still inserted in the pin insertion hole 25 of the die holder 6. In this case, by rotating slightly the partially removed mounting pin 11, one side of the straight line parts 27a on the head 11a of the mounting pin 11 can be rested on the step 27b of the counter bore 27 and the raised state of the mounting pin 11 can be maintained. Due to this, when exchanging the die, the mounting pin 11 can be carried together with the die holder 6 and this eliminates the trouble of storing the mounting pin 11 in a separate place. Moreover, the maintenance of this raised state of the mounting pin 11 is easily achieved by a simple structure comprising only the step 27b. The angle of rotation of the mounting pin 11 when the head 11a of the mounting pin 11 is rested on the step 27b may be an angle such that the straight line part 27a of the head 11a is in alignment with the outer diameter side edge surface of the die holder 6. In short, the straight line part 27a comprises a mark for aligning the angle of rotation. As a result, the mounting pin 11 may be easily rotated by the predetermined angle. Figure 5 is a schematic plan view of a turret punch press utilizing this die holder mounting structure. A table 63 is arranged around the periphery of the lower turret 2 and a work W is enclosed by a work holder 65 of the work delivery device 64 ontop of that and is moved in the X and Y axes. The table 63 comprises a table 63a fixed around the periphery of the turret, a centrally fixed table 63b and a slide table 63c that moves along the Y axis. The table 63a fixed around the periphery of the turret partially comprises a removable table 67 and die 5 exchange is carried out at the place where this is removed. As the die holder mounting structure of the present invention is so arranged that the die holder may be fixed to the lower turret by a mounting pin and the diameter of this mounting pin may be increased or decreased while inserted in the pin insertion hole, the accuracy of the mounting of the die holder is improved and the die holder is fixed firmly. Improvements in the accuracy of the mounting reduce the clearance between the punch and die, reduce the barb of the punched products and improve the product quality. Furthermore, when an alignment plate is arranged on the lower turret and a pin insertion hole is arranged in that alignment plate, the die holder may be firmly held in the axial direction with respect to the alignment plate and held with increased accuracy in the horizontal direction. Yet further, when a non-circular head is arranged on the mounting pin, a counter bore that fits with that head is arranged on the open end of the pin insertion hole of the die holder and a step part on which that head is rested by rotating by a predetermined angle with respect to the positioning hole of the mounting pin is arranged on the upper edge of that counter bore, the mounting pin may be maintained in raised state by a simple structure when a die exchange is to be carried out and a simplification of the die exchange is achieved.

Claims: A die holder mounting structure for a turret punch press arranged with corresponding pin insertion holes (25, 26), that are on the die holder (6) resting on the lower turret (2) and on that lower turret, respectively, a mounting pin (11) that is inserted from the die holder side through both pin insertion holes, and characterised in that the mounting pin is capable of increasing and deacreasing in diameter when inserted in the pin insertion holes. A die holder mounting structure as in claim 1, used in a lower turret (2) having a turret main body and an alignment plate (7) attached to the upper surface of the turret main body so as to be position-adjustable and upon which is loaded the die holder, whereby the pin insertion hole of the lower turret is arranged in the alignment plate. A die holder mounting structure as in claims 1 or 2, wherein a non-circular head (11a) is arranged on the mounting pin (11), a counter bore (27) that fits with that head is arranged on the open end of the pin insertion hole of the die holder and a step part (27b) on which that head is rested by rotating by a predetermined angle with respect to the positioning hole of the mounting pin is arranged on the upper edge of that counter bore.

Inventors: MARUI KENICHI, SAKAMOTO HIROICHI, MARUI, KENICHI, SAKAMOTO, HIROICHI
Applicants: MURATA MACHINERY LTD, MURATA KIKAI KABUSHIKI KAISHA
Application year: 1997
Main classification: B21D28
IPC codes: B23D35, B21D37, B21D28, B26D7