JP2012206152A - Press forming mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To keep a supporting position of a blank holder optionally settable, to give an even cushion pressure to the blank holder, and to provide a locking mechanism of the blank holder with low cost.SOLUTION: A press forming mold includes a damper 50 for giving resistance to vertical movement of the blank holder 30 by viscosity resistance of fluid. When the blank holder 30 is pressed by a die 10, a predetermined cushion pressure is given to the blank holder 30 by the damper 50.

Description

  The present invention relates to a press mold, and more particularly, to a press mold for drawing a blank material.

  Drawing is performed by lowering them together and pressing the blank against the punch, with the end of the blank held between the die and the blank holder. At this time, a force for holding and fixing the blank material is generated by applying a cushion pressure (a force against the pressing force of the die) to the blank holder.

  As a means for applying a cushion pressure to the blank holder, for example, Patent Document 1 shows a configuration in which the blank holder is supported by a cushion pin penetrating the lower mold and the bolster. Specifically, a blank holder is attached to the upper end of the cushion pin, a cushion pad is connected to the lower end of the cushion pin, and the cushion pad can be moved up and down by a drive unit (air cylinder, servo motor, etc.). When the blank holder is pushed down by the die, a predetermined cushion pressure is applied to the blank holder by the drive unit.

JP 2009-279621 A JP-A-8-155558

  However, since the cushion pin is inserted through a through hole provided in the lower mold and the bolster, the position of the cushion pin is determined in advance and cannot be easily changed. Therefore, the blank holder cannot be supported except for the place where the cushion pin is disposed, and the cushion pressure of the blank holder may be insufficient depending on the place. Further, if the length of the cushion pin varies, the cushion pressure may vary due to the blank holder.

  For example, if the blank holder is supported by an elastic member such as a spring, it can be easily installed on a bolster or a mold, so that the installation location can be easily changed. However, if the height of the elastic member varies, the cushion pressure of the blank holder may vary.

  In addition, when the blank holder is moved up and down by an elastic member such as a spring, an upward elastic reaction force is always applied to the blank holder against the pressing force of the die. . During this time, the state where the end of the molded product is sandwiched between the die and the blank holder is maintained, so that the molded product cannot be taken out. Therefore, the blank holder is stopped and only the die is raised, and a molded product is taken out after a predetermined gap or more is formed between the blank holder and the die, resulting in a long cycle time.

  Further, for example, when a blank material is formed into an M-shaped cross section, a middle die may be provided on the die (for example, Patent Document 2). Specifically, as shown in FIG. 11A, the middle mold 111 is biased so as to protrude downward from the die 110 by a biasing means 112 (spring or the like). And by lowering | hanging die | dye 110, the edge part of the blank material w is clamped with the blank holder 130 (refer Fig.11 (a)), the intermediate mold 111 is pressed against the blank material w, and the recessed part w1 is shape | molded (FIG.11). (See (b)). Further, the die 110 is lowered to press the blank material w against the punch 120 to perform drawing (see FIG. 11C). Thereafter, when the die 110 is raised, as shown in FIG. 11 (d), when the blank holder 130 rises as the die 110 rises, the molded product is held in a state where the center portion of the molded product is pressed downward by the middle mold 111. Since both ends of w are lifted by the blank holder 130, the molded product w may be deformed as illustrated.

  For example, a gas spring provided with a locking mechanism that locks the blank holder at the bottom dead center position is also known, but such a gas spring is very expensive and causes an increase in mold cost.

  The problems to be solved by the present invention include that in a press mold, the support position of the blank holder can be freely set, a uniform cushion pressure is applied to the blank holder, and the locking mechanism of the blank holder is reduced. It is in the cost.

  The present invention made to solve the above problems includes a punch, a die, a blank holder, and a damper that supports the blank holder so that it can be raised and lowered, and that imparts resistance to the raising and lowering operation of the blank holder by the viscous resistance of the fluid. A press-molding die provided, wherein when the blank holder is pushed in with a die, a predetermined cushion pressure is applied to the blank holder by a damper.

  A damper using the viscous resistance of a fluid is generally used as a shock absorber for the purpose of absorbing shock. In the present invention, a cushion pressure is applied to the blank holder using this type of damper. That is, while the blank holder is moved (lowered) by being pushed into the die, a force that opposes the pushing force of the die is generated due to the viscous resistance of the fluid, and a predetermined cushion pressure is applied to the blank holder. On the other hand, while the blank holder is stationary, the damper fluid is also stationary, so that no driving force is generated and the blank holder is kept stationary. Therefore, even if the die moves backward to the press forming completion position after the blank holder is moved to the press molding completion position by the press of the die, the stationary blank holder is not pushed up by the damper. That is, by supporting the blank holder with the damper, a locking mechanism for locking the blank holder at the press molding completion position can be provided at low cost without using an expensive device.

  The damper using the viscous resistance as described above does not need to be connected to an external compressor or the like, has a simple structure and is small, and can be provided at an arbitrary position in the mold. Therefore, the support location of the blank holder can be freely set, and the cushion pressure can be made uniform. In addition, the cushion pressure applied by the damper using viscous resistance depends on the moving speed of the blank holder, so even if there is some variation in the length of the pins that support the blank holder, As long as it moves at the same speed, a uniform cushion pressure can be applied.

  Since the above-mentioned damper cannot raise the blank holder stationary at the press forming completion position to the initial position, it is necessary to separately provide a return means for returning the blank holder to the initial position. As such a return means, for example, an air cylinder or a hydraulic cylinder can be provided. Since it is sufficient that the return means has a driving force sufficient to return the blank holder to the initial position, a small one can be used, and the equipment can be downsized.

  Since the above damper has a simple structure and a small size, it can be added to an existing facility. For example, among the blank holders that are lifted and lowered by an existing drive unit, the above-described damper can be additionally provided in a portion that requires a particularly high cushion pressure.

  As described above, by supporting the blank holder with the damper, the support position of the blank holder can be freely set, and a uniform cushion pressure can be applied to the blank holder. The locking mechanism can be provided at low cost.

It is sectional drawing of the press molding die which concerns on one Embodiment of this invention, and shows the state before a press molding start. It is sectional drawing of the damper integrated in the said press molding die, (a) shows a single cylinder type damper, (b) shows a double cylinder type damper. It is sectional drawing of the said press molding metal mold | die, and shows the state which dropped the die | dye and clamped the blank material. It is sectional drawing of the said press molding metal mold | die, and shows a mode that a recessed part is shape | molded in a blank material with a middle mold. It is sectional drawing of the said press molding die, and shows the state which press molding completed. It is sectional drawing of the said press molding die, and shows the state in the middle of raising the die. It is sectional drawing of the said press molding die, and shows the state which raised the die | dye to the top dead center position. It is sectional drawing of the press molding die which concerns on other embodiment, and shows the state which press molding completed. It is sectional drawing of the press molding die of FIG. 8, and shows the state which raised the die | dye to the top dead center position. It is a top view of the press-molding die concerning other embodiments. It is sectional drawing of the conventional press molding metal mold | die, (a) is the state which pinched | interposed the blank material, (b) is in the middle of press molding, (c) is the time of press molding completion, (d) shows the middle of raising of die | dye. .

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, a press mold 1 according to an embodiment of the present invention includes a die 10, a punch 20, a blank holder 30, a plurality of dampers 50 that support the blank holder 30 from below, and a blank. And a plurality of cylinders 60 as return means for returning the holder 30 to the initial position. The die 10 is attached to a slide (not shown) and can be moved up and down. The punch 20, the damper 50, and the cylinder 60 are fixed to the bolster 40. In the present embodiment, a case where the blank material W is formed into a substantially M-shaped cross section is shown.

  The die 10 is provided with a middle die 11 that can be projected and lowered from the lower surface of the die 10. The middle mold 11 is supported by support means provided inside the die 10, and in this embodiment, is biased in a direction protruding downward from the lower surface of the die 10 by a cylinder 12 as support means. The die 10 has a pressing surface 13 provided along the periphery of the blank material W. In this embodiment, an annular pressing surface 13 surrounding the entire periphery of the blank material is provided.

  The blank holder 30 is provided along the periphery of the blank material W, and is provided in an annular shape so as to surround the entire periphery of the blank material W in the present embodiment. The blank holder 30 is supported from below by a plurality of dampers 50. The damper 50 provides resistance to the lifting and lowering operation of the blank holder 30 by the viscous resistance of the fluid, and includes a cylinder 51, a pin 52 protruding upward from the cylinder 51, and a pad provided at the upper end of the pin 52. 53, and the upper surface of the pad 53 is fixed to the lower surface of the blank holder 30.

  The damper 50 can use a well-known thing, for example, can use the single cylinder type damper 50a shown to Fig.2 (a), and the multiple cylinder type damper 50b shown in FIG.2 (b). A single cylinder damper 50a shown in FIG. 2 (a) is shown by a piston 54 arranged so as to be movable up and down inside the cylinder 51, and a fluid filled in the cylinder 51 (for example, oil, scattered dots). ). The space inside the cylindrical body 51 is divided into two spaces 55 a and 55 b by the piston 54, and the spaces 55 a and 55 b are communicated with each other through an oil path 54 a provided in the piston 54. For example, when the piston 54 descends, the oil in the lower space 55b moves to the upper space 55a through the oil path 54a of the piston 54. At this time, resistance is given to the descent operation of the piston 54 by the viscous resistance of the oil flowing through the oil path 54a. When the piston 54 moves up, resistance is applied in the same manner as described above.

  On the other hand, a multi-cylinder damper 50b shown in FIG. 2B includes an inner cylinder 56 arranged inside the cylinder 51, a piston 57 arranged so as to be movable up and down inside the inner cylinder 56, and an inner cylinder. 56 and a fluid (for example, oil, indicated by scattered points) filled in a part of the space 58 between the cylindrical body 51 and the inner cylinder 56. A space inside the inner cylinder 56 is divided into two spaces 59 a and 59 b by the piston 57. The piston 57 is provided with an oil path 57a that communicates the two spaces 59a and 59b. The inner cylinder 56 is provided with an oil path 56 a that communicates the lower space 59 b and the space 58 between the cylinder 51 and the inner cylinder 56. When the piston 57 descends, the oil in the lower space 59b moves to the upper space 59a through the oil path 57a of the piston 57, and at the same time, the cylinder 51 and the inner cylinder 56 pass through the oil path 56a of the inner cylinder 56. It moves to the space 58 between. Resistance is given to the descending operation of the piston 57 by the viscous resistance of the oil flowing through the oil paths 57a and 56a at this time. When the piston 57 moves up, resistance is applied in the same manner as described above.

  According to the dampers 50a and 50b as described above, the resistance when the pistons 54 and 57 move by changing the flow passage area of the oil passages 54a, 56a, or 57a, that is, the cushion pressure applied to the blank holder. Can be adjusted easily. The configuration of the damper 50 is not limited to that shown in FIG. 2, and any configuration may be used as long as it provides resistance to the lifting / lowering operation of the piston using the viscous resistance of the fluid.

  Hereinafter, a method of forming the blank material W by the press mold 1 will be described.

  First, as shown in FIG. 1, the blank material W is placed on the blank holder 30. Then, the die 10 is lowered, and the end portion of the blank material W is sandwiched and fixed between the pressing surface 13 of the die 10 and the upper surface 31 of the blank holder 30 as shown in FIG.

  When the die 10 is further lowered, the blank holder 30 is pushed down by the die 10. As a result, the pistons 54 and 57 (see FIG. 2) of the damper 50 that supports the blank holder 30 descend, and the resistance force that prevents the pistons 54 and 57 from descending due to the viscous resistance of the oil flowing through the oil passages 54a, 56a, and 57a. Is granted. This resistance force prevents the blank holder 30 from being lowered, and an upward force (cushion pressure) that opposes the pressing force of the die 10 is applied. The end of the blank material W is clamped and fixed by the cushion pressure, and the die 10, the blank holder 30, and the blank material W are integrally lowered while maintaining this state.

  When the die 10 is further lowered, as shown in FIG. 4, the blank material W is pressed against the upper surface of the punch 20, the blank material W is pressed from above by the middle mold 11, and the recess W <b> 1 is formed in the blank material W. The Thereafter, when the die 10 is further lowered, the end portion of the blank material W sandwiched and fixed by the die 10 and the blank holder 30 is pulled downward while pressing the concave portion W1 of the blank material W from above with the middle die 11, and is drawn. Is given. Then, as shown in FIG. 5, when the die 10 reaches the bottom dead center position (press molding completion position), the die 10 and the blank holder 30 are stopped, and the press molding of the molded product W ′ having the recess W1 ′ is completed. . At this time, since the blank holder 30 is stopped, the flow of oil inside the cylinder 51 of the damper 50 is also stopped, so that the resistance force (cushion pressure) by the damper 50 disappears.

  Thereafter, when the die 10 is raised, as shown in FIG. 6, the die 10 is moved from the molded product W ′ while pressing the concave portion W1 ′ of the molded product W ′ from above with the middle die 11 biased downward by the cylinder 12. Be separated. At this time, since the blank holder 30 does not receive any force from the damper 50, the blank holder 30 is maintained in a stationary state at the bottom dead center position. Accordingly, the end of the molded product W ′ is not lifted by the blank holder 30, and deformation of the molded product W ′ can be prevented.

  Thereafter, as shown in FIG. 7, the die 10 is further raised, and the molded product W ′ placed on the punch 20 and the blank holder 30 is discharged to the outside of the press mold 1 by a discharge arm (not shown). (Indicated by chain line A in FIG. 7). In order to take out the molded product W ′ in this way, it is necessary to insert a discharge arm between the die 10 and the molded product W ′. However, as described above, the blank holder 30 is stationary at the bottom dead center position. Since the molded product W ′ cannot be lifted up, the gap between the molded product W ′ and the die 10 is formed relatively early. Accordingly, since the discharge arm can be inserted between the die 10 and the molded product W ′ before the die 10 has been raised to the top dead center position, the cycle time can be shortened.

  When the molded product W ′ is discharged from the press mold 1, the pin 61 of the cylinder 60 as the return means is extended upward (see the dotted line in FIG. 1), and the blank holder 30 is returned to the initial position. The cylinder 60 does not need a force that opposes the pushing force of the die 10, and only needs to have a force enough to lift the blank holder 30, so a small-sized one can be used.

  The present invention is not limited to the above embodiment. Hereinafter, although other embodiment of this invention is described, the same code | symbol is attached | subjected to the location which has the same function as said embodiment, and duplication description is abbreviate | omitted.

  In the above embodiment, the case where the die 10 is the upper die and the punch 20 is the lower die is shown. However, the present invention is not limited thereto, and the punch 20 is, for example, as shown in FIG. The die 10 may be a lower mold. In this case, after the die 10 is raised to the top dead center position (press molding completion position) to form the molded product W ′, the die 10 is lowered as shown in FIG. Eject from 2. When the die 10 is lowered in this way, if the middle mold 11 protrudes upward, the molded product W ′ is lifted. Therefore, a locking mechanism is provided in the cylinder 12 that supports the middle mold 11 until the ejection of the molded product W ′ is completed. It is preferable not to protrude from the upper surface of the die 10. In this case, a damper having the same configuration as that of the damper 50 of the above embodiment may be provided instead of the cylinder 12.

  In the press mold 2 described above, when the die 10 is lowered after the die 10 is raised to the top dead center position and the press molding is completed, the lowering of the blank holder 30 is suppressed by the damper 50. The blank holder 30 does not descend with the die 10. Accordingly, since the gap formed between the molded product W ′ and the punch 20 is not blocked by the blank holder 30, a discharge arm (not shown) for taking out the molded product W ′ is provided between the molded product W ′ and the punch 20. It is possible to reduce the cycle time by inserting it at an early stage. Further, when the die 10 is lowered, the blank holder 30 is slowly lowered by its own weight while being resisted by the damper 50 and returns to the initial position, so that a separate return means for returning the blank holder 30 is not necessary.

  Moreover, although said embodiment showed the case where the blank holder 30 was supported only with the some damper 50, it is not restricted to this. For example, the damper 50 can be additionally provided in the existing press mold 3 as shown in FIG. In the press molding die 3, a plurality of holes 41 are provided in the bolster 40, and a cushion pin 70 is provided in each hole 41. The cushion pin 70 is applied with a cushion pressure by a drive unit (not shown) provided outside the press mold 3, specifically, below the bolster 40.

  For example, when the blank holder 30 as shown by a chain line in FIG. 10 is provided in the press molding die 3, there are only four cushion pins 70 that can support the blank holder 30 (70 (A) in FIG. 10). ~ 70 (D)). For this reason, the support of the blank holder 30 becomes unstable, and the cushion pressure may be insufficient in a place where the blank holder 30 is not supported by the cushion pin 70 (for example, places indicated by P1 and P2). By providing the damper 50 in such a press-molding die 3 and supporting the blank holder 30 at a location that cannot be sufficiently supported by the cushion pin 70, the blank holder 30 can be stably supported and a partial lack of cushion pressure can be achieved. Can be resolved. In the illustrated example, two dampers 50 are provided in the vicinity of the locations indicated by P1 and P2 in the region where the blank holder 30 can be supported.

DESCRIPTION OF SYMBOLS 1 Press molding die 10 Die 11 Medium mold 12 Cylinder 20 Punch 30 Blank holder 40 Bolster 50 Damper 50a Single cylinder type damper 50b Double cylinder type damper 51 Cylindrical body 52 Pin 53 Pad 54 Piston 54a Oil path 55a, 55b Space 56 Inner cylinder 56a Oil path 57 Piston 57a Oil path 58, 59a, 59b Space 60 Cylinder (return means)
70 Cushion pin W Blank material W1 Recess W 'Molded product

Claims (2)

A press mold including a punch, a die, a blank holder, and a damper that supports the blank holder so that it can be raised and lowered, and that imparts resistance to the raising and lowering operation of the blank holder by the viscous resistance of the fluid,
A press mold that applies a predetermined cushion pressure to the blank holder by the damper when the blank holder is pushed in by a die.   The press-molding die according to claim 1, further comprising return means for returning the blank holder to the initial position.

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