hinged mold

Abstract

To provide a hinged die in which a fixed punch and a movable punch are aligned from the beginning. [Solution] The hinged die 1 has a fixed punch 10 and a movable punch 20 mounted rotatably around a pin shaft 7. The movable punch 20 has extending ears 27 and is provided with a movable blade 21 that can be aligned horizontally in a straight line with the fixed blade 11. The movable punch 20 can enter an opening M formed in the fixed punch 10 up to a predetermined angle from the angle at which the fixed blade 11 and the movable blade 21 are aligned horizontally in a straight line. Within this angle range, the movable punch 20 is configured so that a partial weight G1 located on the fixed punch 10 side with respect to a vertical line c passing through the center of the pin shaft 7 is greater than a partial weight G2 located on the opposite side.

Description

[Technical Field]

[0001] This invention relates to a hinged die that hangs on the upper die of a press brake. [Background technology]

[0002] A hinged die attached to the upper table of a press brake is known as a punch for bending a workpiece having an overhanging flange. For example, the hinged die (hinge punch) disclosed in Patent Document 1 is comprised of a fixed punch and a movable punch, and the movable punch is attached to the fixed punch via a sloped surface by a bar and a pin that serve as connecting members, allowing it to move up and down freely. The movable punch is provided with a tab that fits under the overhanging flange.

[0003] In the hinge punch of Patent Document 1, a workpiece is bent with the blades of the fixed punch and the movable punch aligned in a straight line. When the hinge punch is then raised, the movable punch hangs horizontally and diagonally inward due to its own weight. At this time, the tabs on the movable punch detach from the underside of the overhanging flange. When bending a workpiece, when the fixed punch is lowered, the movable punch hanging from the fixed punch first contacts the workpiece. When the fixed punch is further lowered, the movable punch slides over the workpiece, positioning its tabs inside the overhanging flange. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-178038 Summary of the Invention [Problem to be solved by the invention]

[0005] With existing hinged dies that have such a movable punch, friction occurs between the movable punch and the workpiece as it slides over it. When the movable punch slides, the workpiece may shift left or right due to friction. If bending is performed after the workpiece has shifted, the workpiece may be defective. Furthermore, when the die is raised, the movable punch hangs down, making the overall height of the die higher than that of a typical die. To reduce friction between the movable punch and the workpiece surface, the press brake's lifting mechanism must move up and down slowly, significantly reducing operating efficiency. Another issue is that the friction between the workpiece and its surface can cause die wear.

[0006] SUMMARY OF THE INVENTION The object of the present invention is to provide a new hinged die in which the fixed punch and the movable punch are already assembled from the beginning in order to solve the above problems. [Means for solving the problem]

[0007] To achieve the above object, the hinged die of the present invention comprises a fixed punch having a fixed blade at its lower end; a movable punch that is rotatably attached around a pin shaft provided at an end of the fixed punch in the length direction, has a tab extending in the length direction of the fixed punch, and has a movable blade that is horizontally alignable with the fixed blade and is provided at its lower end including the tab, the movable punch has a limited rotatable angle range about the pin axis so that the movable punch can enter an opening formed in the fixed punch up to a predetermined angle from an angle at which the fixed blade and the movable blade are horizontally aligned in a straight line, The movable punch is characterized in that, within the angular range, the weight of the portion of the movable punch located on the fixed punch side with respect to a vertical line passing through the center of the pin axis is greater than the weight of the portion of the movable punch located outside the fixed punch side with respect to the vertical line. [Effects of the Invention]

[0008] According to this invention, the hinged die maintains the fixed punch and the movable punch aligned from the beginning in both the natural state and the operating state, so that friction between the movable punch and the surface of the workpiece due to movement of the movable punch does not occur, which effectively reduces the bending defect rate, shortens the bending time, improves production efficiency, and increases the stability of the product. [Brief explanation of the drawings]

[0009] [Figure 1] 1A and 1B are front, rear and side views of a hinged mold in its natural state. [Figure 2] 1A and 1B are exploded and operational views of a hinged mold; [Figure 3] 10A and 10B are diagrams showing the actual working process of a hinged mold. [Figure 4] FIG. 10 is a diagram showing a modified example of a hinged mold. DETAILED DESCRIPTION OF THE INVENTION

[0010] 1A is a diagram showing a hinged die 1, with FIG. 1A being a front view, FIG. 1B being a rear view, and FIG. 1C being a side view. The hinged die 1 of this embodiment has a fixed punch 10 and a movable punch 20. A fixed blade 11 is provided at the lower end of the fixed punch 10. The movable punch 20 is attached so as to be rotatable about a pin shaft 7 provided at an end of the fixed punch 10 in the longitudinal direction. The pin shaft 7 is not attached directly to the fixed punch 10, but is fixed via a connecting plate 14 which is fixed to the fixed punch 10 by a plurality of bolts 8.

[0011] A clamped portion 12 extends from the top of the fixed punch 10, and a horizontal clamping groove 13 is formed on the back surface of the clamped portion 12. The clamping groove 13 is used for attachment to the upper table of a press brake.

[0012] The movable punch 20 has a tab 27 that extends outward in the longitudinal direction of the fixed punch 10 (to the left in FIG. 1A). A movable blade 21 is provided at the lower end of the movable punch 20, including the tab 27. The tips of the fixed blade 11 and the movable blade 21 are aligned horizontally in a straight line.

[0013] 1B and 1C, a rectangular parallelepiped block 25 is fixed to the top of the movable punch 20 by a connecting bolt 26. The horizontal width of the block 25 is smaller than the distance between the block 25 and the outer wall of the movable punch 20 in the axial direction of the pin shaft 7. The block 25 abuts against the bottom 16 of the stopper groove 15 provided on the fixed punch 10, thereby restricting counterclockwise rotation of the movable punch 20 in FIG. 1A. In this position, the tips of the fixed blade 11 and the movable blade 21 are aligned horizontally. Furthermore, both walls 17 of the stopper groove 15 also restrict axial movement of the pin shaft 7 of the movable punch 20. Meanwhile, the fixed punch 10 has an opening M to prevent interference with the movable punch 20 up to a predetermined rotation angle when the movable blade 21 of the movable punch 20 rotates counterclockwise toward the fixed punch 10 in FIG. 1A.

[0014] 2A and 2B are diagrams further illustrating the hinged die 1, with FIG. 2A being an exploded view and FIG. 2B being an operational diagram. In FIG. 2, the connecting plate 14, which hides the movable punch 20 behind it, is shown perspectively with dashed lines for ease of understanding. Referring to FIG. 2A, the opening M is a space formed by the arcuate side surface 18 and the inclined side surface 19. The center of the arcuate side surface 18 is located on the axis of the pin shaft 7. An abutment surface 23 and a slide surface 22 are provided at the inner end of the movable punch 20, in that order from top to bottom, and lead to the movable blade 21. The abutment surface 23 is an arcuate surface in side view that comes into surface contact with the arcuate side surface 18.

[0015] In FIG. 2B , the block 25 can rotate counterclockwise from the position where it abuts the bottom 16. During this rotation, the slide surface 22 slides on the arcuate side surface 18. The movable punch 20 rotates counterclockwise and can advance toward the fixed punch 10 up to a predetermined angle at which the abutment surface 23 abuts against the inclined side surface 19. Furthermore, within this rotational angle range of the movable blade 21, the weight G1 of the portion of the movable punch 20 located on the fixed punch 10 side of the pin shaft 7 (right side in FIG. 2B ) is greater than the weight G2 of the portion of the movable punch 20 located on the opposite side of the vertical line c (shown as a chain line) passing through the center of the pin shaft 7 (left side in FIG. 2B ). Therefore, the movable punch 20 attempts to rotate around the pin shaft 7 in a direction that causes the tips of the fixed blade 11 and the movable blade 21 to align horizontally in a straight line. When the fixed blade 11 and the movable blade 21 are aligned horizontally, the block 25 on the movable punch 20 side comes into contact with the bottom 16 on the fixed punch 10 side, restricting the movable punch 20 from continuing to rotate any further. As a result, the fixed blade 11 of the fixed punch 10 and the movable blade 21 of the movable punch 20 are aligned horizontally in the natural state when the hinged die 1 is attached to the upper table of the press brake.

[0016] The operation of the hinged die 1 will be described with reference to FIG. 3. The hinged die 1 in FIG. 3 has movable punches 20 on both sides of a fixed punch 10. The workpiece w is pre-formed with vertically rising flanges SF on both sides and a horizontal flange F1 overhanging the upper end of the flange SF. A first bending process and a second bending process are performed on the workpiece w along a first bending line b1 and a second bending line b2. First, the fixed blade 11, the movable blade 21, and the die Di are aligned with the first bending line b1 (FIG. 3A). The hinged die 1 is pressed downward toward the surface of the workpiece w. The fixed blade 11 and the movable blade 21 simultaneously contact the surface of the workpiece w, performing a first bending process along the first bending line.

[0017] Once the first bending process is complete, the hinged die 1 is lifted slightly upward to separate the fixed blade 11 and the movable blade 21 from the surface of the workpiece w. Next, the workpiece w is pushed in, and the positions of the fixed blade 11, the movable blade 21, and the die Di are aligned with the second bending line b2 (FIG. 3B). At this time, the ear 27 of the movable punch 20 is recessed under the flange F1 of the workpiece w.

[0018] Next, the hinged die 1 is driven downward, and a second bending operation is performed on the second folding line b2 of the workpiece w. At this point, the bending of the workpiece is completed (FIG. 3C). As the hinged die 1 is raised, the ear 27 comes into contact with the flange F1 of the workpiece w. The movable punch 20 rotates around the pin axis 7 (FIG. 3D). The movable punch 20 rotates until the ear 27 is completely separated from the flange F1. Thereafter, the movable punch 20 returns to a state in which the fixed blade 11 and the movable blade 21 are horizontally aligned due to the force of its own gravity.

[0019] According to this embodiment, when the press brake lowers the hinged die 1 during bending, the fixed blade 11 and the movable blade 21 are positioned on the same straight line, so that the fixed blade 11 and the movable blade 21 simultaneously come into contact with the surface of the workpiece. This prevents the workpiece from being displaced in the left-right direction during press working, reduces the rate of bending defects, and improves the product stability of the workpiece.

[0020] The end of the fixed blade 11 may be provided with a chamfered portion 110, as shown in Figure 4. This improves the service life of the fixed blade 11 and prevents breakage during bending. [Explanation of symbols]

[0021] 1 hinged mold 7-pin shaft 8 volts 10 Fixed punch 11 Fixed Blade 12 Clamped part 13 Clamp groove 14 Connecting plate 15 Stopper groove 16 Bottom 17 Both walls 18 Arc side 19 Slanted side 20 Movable Punch 21 Movable Blade 22 Slide surface 23 Contact surface 25 blocks 26 Connecting bolt 27 Ears 110 Chamfered part

Claims

1. a fixed punch having a fixed blade at its lower end; a movable punch that is rotatably attached around a pin shaft provided at an end of the fixed punch in the length direction, has a tab extending in the length direction of the fixed punch, and has a movable blade that is horizontally alignable with the fixed blade and is provided at its lower end including the tab, the movable punch has a limited rotatable angle range about the pin axis so that the movable punch can enter an opening formed in the fixed punch up to a predetermined angle from an angle at which the fixed blade and the movable blade are horizontally aligned in a straight line, The hinged die is characterized in that the movable punch is configured such that, within the angular range, the weight of the portion of the movable punch located on the fixed punch side with respect to a vertical line passing through the center of the pin axis is greater than the weight of the portion of the movable punch located outside the fixed punch side with respect to the vertical line.

2. 2. The hinged die according to claim 1, wherein the fixed punch has a connecting plate fixed by a bolt, and the pin shaft is fixed to the connecting plate.

3. In the hinged die according to claim 1, the opening is defined by an arcuate side surface and an inclined side surface on the fixed punch side, and the arc center of the arcuate side surface is located on the central axis of the pin shaft, On the other hand, the hinged die is characterized in that the movable punch is provided with a slide surface that slides on the arcuate side surface and an abutment surface that abuts against the inclined side surface when rotated to the specified angle.

4. In the hinged die according to claim 1, a rectangular parallelepiped block is fixed to the movable punch, and a stopper groove having both walls and a bottom that face each other in the axial direction of the pin shaft is provided in the fixed punch, A hinged mold, characterized in that, when the fixed blade and the movable blade are aligned horizontally in a straight line, the block is restricted in its axial movement of the pin shaft by the both walls of the stopper groove.

5. 2. The hinged mold according to claim 1, wherein the end of said fixed blade is chamfered by a circular arc.

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