EP0893171A1 - Methods for constructing a die for press bending machine and determining cushion forces therefore - Google Patents
Methods for constructing a die for press bending machine and determining cushion forces therefore Download PDFInfo
- Publication number
- EP0893171A1 EP0893171A1 EP98113902A EP98113902A EP0893171A1 EP 0893171 A1 EP0893171 A1 EP 0893171A1 EP 98113902 A EP98113902 A EP 98113902A EP 98113902 A EP98113902 A EP 98113902A EP 0893171 A1 EP0893171 A1 EP 0893171A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- press
- die
- contour
- prototypes
- pair
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D37/00—Tools as parts of machines covered by this subclass
- B21D37/20—Making tools by operations not covered by a single other subclass
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D22/00—Shaping without cutting, by stamping, spinning, or deep-drawing
- B21D22/20—Deep-drawing
- B21D22/22—Deep-drawing with devices for holding the edge of the blanks
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D24/00—Special deep-drawing arrangements in, or in connection with, presses
- B21D24/02—Die-cushions
Definitions
- the present invention relates to methods for preparing production activities in which a plate-like deformable material (blank) is bent into a desired shape by press working or stamping.
- the present invention relates to methods for designing a press die in a relatively short time and methods for optimizing press or stamping conditions in a relatively short time.
- This specification describes a series of processes, such as designing the press die, optimizing the press conditions, performing press working and actually pressing or stamping the blank into the desired shape.
- a press die (usually a punch and a die) is first designed and manufactured and a plurality of prototypes are produced using a variety of press conditions.
- the press conditions are determined based upon factors that are known to influence the final shape of the pressed prototypes, such as the clamping pressure of the punch and die, the pressure (cushion pressure) applied to the outer periphery of the material to be pressed, the shape of the material before press working and the position of the material within the press die when the press working operation is initiated.
- the press die can be modified or redesigned if defects, such as ruptures, wrinkles or a failure to meet a predetermined shape accuracy, are found on the pressed prototypes.
- the shape of the punch and/or die typically is adjusted. For instance, the radius of a circular surface of the press die can be increased if ruptures are found in the pressed prototypes, and the shape of the press die can be modified if the shape of the pressed prototype fails to meet the predetermined shape accuracy.
- Press conditions also can be adjusted in response to the results of the prototyping operation. For example, the clamping pressure (cushion pressure) exerted on the outer periphery of the material can be increased if wrinkles appear in the pressed prototypes.
- the clamping pressure cushion pressure
- the press die is treated as a rigid body and the clamping pressure exerted on the outer periphery of the blank (deformable material) is assumed to be uniform along the entire length of the outer periphery of the material in the mathematical models for these simulations.
- FIG. 11 An example of such a mathematical model can be described with reference to FIG. 11.
- This computer calculation simulates the phenomena that arise when the outer periphery of a plate-like material 102 (blank) is clamped or pressed by die 100 and cushion ring 104 while an inner sphere of material 102 is press worked between die 100 and punch 106.
- deformation of material 102 is calculated using the assumption that die 100, punch 106 and cushion ring 104 are rigid bodies and that the clamping pressure applied to the outer periphery of material 102 between die 100 and cushion ring 104 is uniformly distributed along the entire length of the outer periphery of material 102.
- an object of the present invention is to provide simulation techniques that produces a model that closely approximates actual press working results.
- Another object of the invention is to provide techniques that can determine optimum clamping pressures in a relatively short time based upon the results of the simulations taught herein.
- Methods for designing a press bending die preferably comprise performing computer simulations to model the intended press bending operation and manufacturing several prototypes under several clamping conditions to identify the proper clamping pressure.
- the simulation preferably is performed with the assumption that the distance between a pair of holddown parts, which parts exert clamping pressure on the periphery of the material during the press working operation, is fixed as a constant value.
- the contour of the bent material after the press working operation as calculated by the computer simulation, closely approximates the contour of the bent material that is actually press worked.
- the press die can be treated as the rigid body, and the deformation of the press die need not be calculated.
- the clamping pressure required to keep the distance of the clamping parts at the value used in the computer simulation process need not be calculated.
- prototypes of the desired bent product may be manufactured using a variety of clamping pressures in order to determine the optimal clamping pressure for the press working operation.
- the contours of the prototypes thus manufactured are compared with contours calculated using the computer simulations and the optimal clamping pressure is then determined based upon this comparison.
- FIG. 12 In which reference numeral 102a depicts the outer periphery of the blank prior to press working, and 102b designates the outer periphery of the blank after press working.
- Reference numeral 108 designates the inner periphery of the final product formed by press working.
- pressure distribution may be calculated by the computer, such calculation will not provide a good result as long as the press die is treated as a rigid body, because the press die is deformed in the actual press working due to the pressure concentration on the partial contact areas C1, C2.
- the deformation of the press die could be calculated in accordance with the clamping pressure distribution.
- this calculation requires a substantial number of calculations, and therefore is not practical using currently available simulation techniques.
- Step S10 conditions to perform press working
- press conditions conditions to perform press working
- the above-described press, (boundry) conditions may be input into the computer program, including such information as the shape of the press die (die and punch), the distance between a pair of holddown parts, the shape of the blank prior to press working, the physical properties of the blank and the position of the blank with respect to the press die.
- Some press machines include a bead section within the press die, and information about the shape of the bead is accordingly utilized in the computer simulation when such a press machine is used.
- the cushion force exerted on the blank by the pair of holddown parts is not utilized as a boundry condition in the present simulation. Instead, the distance between the pair of holddown parts is utilized as a boundry condition.
- this model and this set of boundry conditions phenomena that arise during press working are simulated on the computer based on the inputted press (boundry) conditions (Step S12).
- LS-DYNATM Livermore Software Technology Corporation in California, U.S.A. is utilized to perform the present simulations.
- Step S30 simulations of the drawing process are performed first (Step S30).
- This simulation process S30 covers the steps of setting material 14 in press machine 10 as shown in FIG. 3 , securing the outer periphery of material 14 between a pair of holddown parts 12a and 16a with die 12 moved downward-as shown in FIG. 4, and press working the material with die 12 moved further downward as shown in FIG. 5.
- a contour of press bent material 14 (a pressed product) is thus obtained as a result of the simulation.
- This simulation is performed using the assumption that die 12, cushion ring 16 and punch 18 are rigid bodies and therefore none of these elements deform during the press working operation.
- each of holddown parts 12a, 16a comprise a portion of die 12 and cushion ring 16, respectively.
- a distance G between the pair of holddown parts 12a, 16a is fixed at a value in which preferably a predetermined distance ⁇ is added to the thickness t of material 14 .
- the predetermined distance ⁇ can be derived from the shape and mechanical properties of material 14. Under actual press working conditions, the distance ⁇ may vary in certain portions of material 14. However, the variations of the distance ⁇ are so small that good simulation results can be obtained by treating this distance as a constant along the entire length of the periphery of material 14. For this reason, a constant value is preferably utilized as the predetermined distance ⁇ for the entire periphery of material 14. In this representative embodiment, the distance ⁇ is set to be equal to 5% of the thickness t of material 14. Accordingly, the distance between the pair of holddown parts G is treated as constant (105% of the material thickness) over the entire periphery of material 14 in this simulation.
- FIGS. 3 to 5 show a cross section of a preferred die and punch set.
- holddown parts 12a, 16b completely encircle punch 18, such that holddown parts 12a, 16b clamp or hold the entire periphery of blank 14.
- Holddown part 12a is disposed at the bottom of die 12 and holddown part 16a is disposed at the top of cushion ring 16.
- a convex bead shaped portion 12b is disposed within holddown part 12a and a concave bead shaped portion 16b is disposed within holddown part 16a.
- the bead section for the press bending machine preferably is composed of convex portion of bead 12b and concave portion of bead 16b and beads 12b and 16b cooperate to apply a resistance force to blank 14 when it is being drawn inwardly during the press working process.
- the cushion force is applied to blank 14 through die 12 and cushion ring 16 by machine cushion 20.
- the amount of the material that is drawn inwardly may be controlled by the above-noted resistance force and cushion force.
- Step S30 When the simulation for the drawing process is completed in Step S30, a stamping (trimming) simulation (Step S32) and a bending simulation (Step S34) are performed.
- stamping simulation material 14 is stamped by a stamping press machine and the contour of the stamped material is calculated.
- bending simulation material 14 is bent by a bending press machine and the contour of the bent material is calculated.
- Step S36 a removing simulation is performed as the final stage of the simulations.
- the material is removed from the drawing die, stamping die and bending die, respectively, after each step of drawing, stamping and bending.
- the material is removed from the die only after the bending process is completed.
- the contour of material 14 after removal from the die is calculated considering additional factors, such as elastic recovery in which the blank assumes a shape that is intermediate between the original shape and the shape immediately before removal from the die.
- contours that closely approximate the actual pressed product can be calculated using the present teachings.
- Step S14 is performed as shown in FIG. 1.
- the contour of the material calculated by simulations in Step S12 is displayed on a computer screen (or printed out) and is examined for defects in the desired shape (Step S14). Potential defects include the contour not having a predetermined accuracy, ruptures, wrinkles and excessive concentration of stress in the material. These defects can be determined from the results of the computer simulation.
- Step S10 and S12 are repeated using new boundry conditions until the defects are eliminated.
- the shapes of the die and punch or the shapes of bead sections may be changed.
- a press die is manufactured based on the shape of the die and the punch thus calculated (Step S16). For example, die 12, cushion ring 16 and punch 18 are manufactured for press machine 10 shown in FIG. 3. Then, the press die (die 12, cushion ring 16 and punch 18) is mounted in the press machine, and prototypes are manufactured. A plurality of prototypes are manufactured using a variety of different cushion forces (Step S18). For example, in the case of press machine 10 shown in FIG. 3, the strength of the cushion force exerted on the outer periphery of material 14 can be altered by cushion machine 20.
- contour line 56 of unbent blank 14 may be drawn on the press die manufactured in Step S16 (Step S17). This contour line 56 is drawn in order to ensure that the operator places blank 14 onto holddown part 52a in the same exact location that was utilized in the computer simulations of Step S12. Contour line 56 may be drawn by etching die 52 or by marking with a pen by using a plotter, a robot arm or similar devices. Also, as shown in FIG. 10, contour line 58 of the simulated press product after bending may be marked on holddown part 52a in order to evaluate the results of the press bending prototyping operation. That is, the contour of the simulated product can be compared to the contour of the actual product to determine whether the cushion force is appropriate.
- contour line 56 of unbent blank 54 is directly drawn on the press die, blank 54 can be positioned in the press die more accurately. With the more accurate positioning of unbent blank 14, the difference in inflows of the materials for various clamping pressures can be more accurately determined. Therefore, the optimal clamping force for obtaining press bent product 54 that closely approximates the contour of the simulated press bent product can be quickly determined.
- a pressed prototype having a contour that closely approximates the simulated contour obtained in Step S12 can be determined by manufacturing a plurality of prototypes in Step S18 using a variety of cushion forces.
- the optimal cushion force can be selected by identifying the pressed prototype that most closely resembles the desired simulated product (Step S20).
- Differences between the shapes indicate differences in inflows of the materials that are actually drawn by the press die from the inflows that are predicted by the simulation.
- Table 1 shows differences between the shapes of five prototypes and the shapes predicted by the simulation for five different cushion forces.
- the difference is shown as a negative value and if the solid line is outside the one dot chain line, the difference is shown as a positive value.
- the cushion force is 30[T/cm 2 ]
- the cushion force is too low and too much of the material is drawn inward by the bending action of punch 18 on blank (material) 14 as shown in FIG. 5.
- the shape of the pressed prototype is smaller than the simulated result.
- the cushion force is 75[T/cm 2 ]
- the force is too high and only a limited amount of material is permitted to be drawn inward. Therefore, the shape of the pressed prototype is larger than the simulated result.
- the difference between the simulated contour and the prototype shape are the smallest when the cushion force is 40[T/cm 2 ].
- the press die or the press conditions may be modified by reviewing the pressed product which is press bent with the cushion force determined in Step S20 (Step S22).
- the resistance force by the bead section can be decreased if any breakage is found in the bent product by decreasing the radius R1 of the convex bead 12b in FIG. 7(A) to the radius R2 (R2 ⁇ R1) as shown in FIG. 7(B).
- the height of the convex portion of bead 12b can be lowered such that it is not semi-spherically shaped.
- the resistance force by the bead section can be increased, if wrinkles are found, by widening radius R1 of the convex section of bead 12b in FIG. 7(A).
- portions of the bent product may not have scratches on the surfaces. Scratches arise when material 14 contacts holddown parts 12a and 16a. Portions of the bent product having no scratches indicate that no cushion force has been exerted on those portions and is shown as a gap between die 12 and blank 14 in FIG. 8(A).
- an additional cushion layer 12c can be added, by welding for example, to bring blank 14 into contact with die 12a, as shown in the FIG. 8(B).
- a uniform cushion force can be exerted over the entire outer periphery of material 14 and thereby prevent the concentration of stress in the bent product.
- Step S12 the simulation of Step S12 is performed using the condition that the distance between the pair of holddown parts is fixed as a constant value, so that the phenomena approximate to those in the actual press working operation can be simulated in spite of the assumption that the press dies are rigid bodies. Therefore, the press die manufactured in the Step S16 and the press conditions determined in Step S20 are very close to the optimum from the beginning and Step S22 can be completed in a relatively short time.
- Step S12 simulation process
- the above Step S12 utilizes the condition that the distance between the pair of holddown parts is fixed as the constant, instead of the known prerequisite that the cushion force is fixed as the constant. Therefore, the contour of the pressed material that is more closely approximate to those of the actual pressed material can be calculated by simulations. Accordingly, it has become possible to manufacture the press die after the shape of the press die for producing the pressed material with the desired shape becomes clear.
- the optimum cushion force to be exerted on the outer periphery of the material is not determined from the simulation in Step S12. Rather, in this embodiment, the optimum force can be selected in a relatively short time from the sequence of the processes that the press die is manufactured based on the shape of the press die calculated in Step S12 (die manufacturing process of Step S16), prototypes are manufactured using the press die so manufactured with cushion force of varying strength (prototype manufacturing process of Step S18), then, the optimum cushion force is determined by comparing the contours of the prototypes with that of the simulation (clamping pressure determining process of Step S20). In this sequence of processes, it is possible to determine the press conditions that produce the pressed product approximate to the pressed product calculated in the simulation process in a relatively short time.
Abstract
Description
Claims (8)
- A method for constructing a press bending machine for bending a plate-like deformable material, comprising the steps of:calculating using a finite element method a contour of a bent material after press working by simulating phenomena that arise when an inner periphery of said material is press worked between a pair of press dies while an outer periphery of said material is clamped between a pair of holddown parts, under a condition that a distance between said pair of holddown parts is fixed as a constant;constructing a press die in accordance with the result of said calculation.
- A method as in claim 1 further comprising the steps of:manufacturing a plurality of prototypes by using said press die, and altering clamping pressure being exerted on said outer periphery of the material of each prototype; anddetermining the clamping pressure that produces a contour that is most approximate to said calculated contour by comparing said calculated contour with those of the plurality of prototypes.
- A method according to claim 2, wherein the constant is a thickness of the material added to a predetermined thickness.
- A method according to claim 2 wherein a contour line is drawn on one press die and/or prototypes along the contour obtained by the calculation step.
- A method according to claim 2 wherein a contour line of the material before press bending is drawn on one press die.
- A method of determining clamping pressure to be exerted on a pair of holddown parts, comprising the steps of:calculating a contour of a bent material after press working by simulating phenomena that arise when an inner periphery of said material is press worked between a pair of press dies while an outer periphery of said material is clamped between the pair of holddown parts under a condition that a distance between the pair of holddown parts is fixed as a constant;constructing a press bending machine based on the result of said calculation step;manufacturing a plurality of prototypes by using said press bending machine and altering clamping pressure exerted on said outer periphery of the material of each prototype; anddetermining the clamping pressure that produces a contour that is most approximate to said calculated contour by comparing said calculated contour with those of the plurality of prototypes.
- A method according to claim 6 wherein a contour line is drawn on one press die and/or prototypes along the contour obtained by the calculation step.
- A method according to claim 6 wherein a contour line of the material before press working is drawn on one press die.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP19889997 | 1997-07-24 | ||
JP19889997 | 1997-07-24 | ||
JP198899/97 | 1997-07-24 |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0893171A1 true EP0893171A1 (en) | 1999-01-27 |
EP0893171B1 EP0893171B1 (en) | 2001-10-17 |
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ID=16398801
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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EP19980113902 Expired - Lifetime EP0893171B1 (en) | 1997-07-24 | 1998-07-24 | Methods for constructing a die for press bending machine and determining cushion forces therefore |
Country Status (2)
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EP (1) | EP0893171B1 (en) |
DE (1) | DE69802047T2 (en) |
Cited By (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2007087867A1 (en) * | 2006-01-13 | 2007-08-09 | Audi Ag | Apparatus and method for the final processing of a forming tool for a sheet-metal body part |
FR2960325A1 (en) * | 2010-05-21 | 2011-11-25 | Peugeot Citroen Automobiles Sa | Method for digitally designing e.g. stamping tool utilized to stamp sheet metal blank for forming automobile body part, involves computing resistance of die to deliver die displacement and/or constraint mapping, for computing die structure |
US10918820B2 (en) | 2011-02-11 | 2021-02-16 | Batmark Limited | Inhaler component |
US11083856B2 (en) | 2014-12-11 | 2021-08-10 | Nicoventures Trading Limited | Aerosol provision systems |
US11253671B2 (en) | 2011-07-27 | 2022-02-22 | Nicoventures Trading Limited | Inhaler component |
CN115069900A (en) * | 2022-07-13 | 2022-09-20 | 海盐东通家居有限公司 | Progressive die for production of press handle connecting rod |
US11524326B2 (en) * | 2017-09-04 | 2022-12-13 | Bayerische Motoren Werke Aktiengesellschaft | Method for operating a forming press |
US11744964B2 (en) | 2016-04-27 | 2023-09-05 | Nicoventures Trading Limited | Electronic aerosol provision system and vaporizer therefor |
Families Citing this family (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE102004054679B4 (en) * | 2004-11-12 | 2006-09-07 | Audi Ag | Method for producing a forming tool |
DE102010047082A1 (en) * | 2010-10-01 | 2012-04-05 | Benteler Automobiltechnik Gmbh | Method for producing e.g. die utilized for producing ultra-high-strength structural components in passenger car body, has optimizing contact surfaces, and producing tool with optimized tool geometry by machining process |
DE102012207474A1 (en) * | 2012-05-07 | 2013-11-07 | Bayerische Motoren Werke Aktiengesellschaft | Method of making a tool |
DE102013204011A1 (en) * | 2013-03-08 | 2014-09-11 | Bayerische Motoren Werke Aktiengesellschaft | Method for designing a forming tool |
Citations (3)
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US5379227A (en) * | 1992-12-21 | 1995-01-03 | Ford Motor Company | Method for aiding sheet metal forming tooling design |
US5463558A (en) * | 1994-02-04 | 1995-10-31 | Ford Motor Company | Method for designing a binder ring surface for a sheet metal part |
EP0773075A2 (en) * | 1992-11-05 | 1997-05-14 | Toyota Jidosha Kabushiki Kaisha | Method and device for controlling, checking or optimizing pressure of cushion pin cylinders of press by discharging fluid or initial pressure |
-
1998
- 1998-07-24 EP EP19980113902 patent/EP0893171B1/en not_active Expired - Lifetime
- 1998-07-24 DE DE1998602047 patent/DE69802047T2/en not_active Expired - Fee Related
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0773075A2 (en) * | 1992-11-05 | 1997-05-14 | Toyota Jidosha Kabushiki Kaisha | Method and device for controlling, checking or optimizing pressure of cushion pin cylinders of press by discharging fluid or initial pressure |
US5379227A (en) * | 1992-12-21 | 1995-01-03 | Ford Motor Company | Method for aiding sheet metal forming tooling design |
US5463558A (en) * | 1994-02-04 | 1995-10-31 | Ford Motor Company | Method for designing a binder ring surface for a sheet metal part |
Cited By (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2007087867A1 (en) * | 2006-01-13 | 2007-08-09 | Audi Ag | Apparatus and method for the final processing of a forming tool for a sheet-metal body part |
CN101356025B (en) * | 2006-01-13 | 2010-12-01 | 奥迪股份公司 | Apparatus and method for the final processing of a forming tool for a sheet-metal body part |
FR2960325A1 (en) * | 2010-05-21 | 2011-11-25 | Peugeot Citroen Automobiles Sa | Method for digitally designing e.g. stamping tool utilized to stamp sheet metal blank for forming automobile body part, involves computing resistance of die to deliver die displacement and/or constraint mapping, for computing die structure |
US10918820B2 (en) | 2011-02-11 | 2021-02-16 | Batmark Limited | Inhaler component |
US11253671B2 (en) | 2011-07-27 | 2022-02-22 | Nicoventures Trading Limited | Inhaler component |
US11083856B2 (en) | 2014-12-11 | 2021-08-10 | Nicoventures Trading Limited | Aerosol provision systems |
US11744964B2 (en) | 2016-04-27 | 2023-09-05 | Nicoventures Trading Limited | Electronic aerosol provision system and vaporizer therefor |
US11524326B2 (en) * | 2017-09-04 | 2022-12-13 | Bayerische Motoren Werke Aktiengesellschaft | Method for operating a forming press |
CN115069900A (en) * | 2022-07-13 | 2022-09-20 | 海盐东通家居有限公司 | Progressive die for production of press handle connecting rod |
Also Published As
Publication number | Publication date |
---|---|
EP0893171B1 (en) | 2001-10-17 |
DE69802047D1 (en) | 2001-11-22 |
DE69802047T2 (en) | 2002-07-04 |
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