JP4986955B2 - Molding condition determination method - Google Patents

Description

  The present invention relates to a molding condition determination method. For example, the present invention relates to a molding condition determination method for press molding for manufacturing an automobile body.

Conventionally, a body of an automobile is formed by drawing a steel plate with a press machine.
In such a pressing process, for example, a servo press using a servo motor is used. According to this servo press, the slide speed and die cushion pressure of the upper mold can be freely changed during molding, so that the degree of freedom of press molding is high and the cycle time can be shortened.

By the way, in the above pressing process, optimum molding conditions are determined by actually repeating trial manufacture of a molded product using a press machine.
For example, a prototype is prepared in advance, and the minimum value and the maximum value of the die cushion pressure at which the quality of the molded product can satisfy a certain standard for each slide speed are obtained and stored in a database. At the time of press molding, the minimum value and the maximum value of the die cushion pressure are read from this database according to the slide speed, and the die cushion pressure is set to an intermediate value between the minimum value and the maximum value (see Patent Document 1). .
According to this method, the die cushion pressure can be easily set according to the slide speed.
JP 2001-96314 A

However, in the method disclosed in Patent Document 1, the die cushion pressure is uniquely determined according to the slide speed, and is not necessarily the optimum molding condition of the servo press machine.
Therefore, in actuality, in the servo press machine, it is necessary to make a large number of trials in order to determine the optimum values of the slide speed and the die cushion pressure, resulting in an increase in man-hours and costs. There is a problem.

  An object of this invention is to provide the molding-conditions determination method of the press which can reduce cost.

  The molding condition determination method of the press machine of the present invention is a molding condition determination method for determining the molding condition of the press machine. The molding simulation analysis is executed under initial conditions, the result of the molding simulation analysis is evaluated, and the evaluation is performed. Is positive, the first analysis procedure (for example, steps S11 to S13 described later) in which the molding conditions of the current molding simulation analysis are optimum values and the evaluation of the first analysis procedure are negative. In this case, change the die cushion pressure to execute the molding simulation analysis, evaluate the result of the molding simulation analysis, and if the evaluation is affirmative, set the molding conditions of the molding simulation analysis to the optimum value. The second analysis procedure (for example, steps S14 to S17 described later) and the evaluation of the second analysis procedure are negative due to the occurrence of wrinkles In some cases, the die cushion pressure is changed and a molding simulation analysis is performed, and the result of the molding simulation analysis is evaluated. If the evaluation is positive, the molding conditions of the molding simulation analysis are optimized. If the third analysis procedure (for example, steps S21 to S23 described later) and the evaluation of the second analysis procedure are negative due to the occurrence of cracks in the drawing region, the die cushion pressure is changed. Then, the molding simulation analysis is performed, and the result of the molding simulation analysis is evaluated. If the evaluation is affirmative, the fourth analysis procedure (for example, the molding condition of the molding simulation analysis is set to the optimum value) Steps S18, S19, S22, S23 described later and the evaluation of the second analysis procedure are caused by the occurrence of cracks in the overhang forming region. If the evaluation is negative, the slide simulation speed is changed and the molding simulation analysis is executed. The result of the molding simulation analysis is evaluated. If the evaluation is positive, the molding simulation analysis of this time is performed. A fifth analysis procedure (for example, steps S18, S20, S22, and S23, which will be described later) having an optimum value as a condition, and the evaluation of the third, fourth, and fifth analysis procedures is denied due to the occurrence of wrinkles If yes, return to the third analysis procedure, and if negative, due to the occurrence of cracks in the draw forming region, return to the third analysis procedure, and negate due to the occurrence of cracks in the overhang forming region. If it is correct, the process returns to the fifth analysis procedure.

  In this case, it is preferable that the initial conditions of the first analysis procedure include that the slide speed is maximum and the die cushion pressure is constant.

  In this case, when the die cushion pressure is changed in the second analysis procedure, the die cushion pressure at the start of molding is set to a first predetermined value, the die cushion pressure at the time of molding completion is set to a second predetermined value, and the first predetermined value is set. It is preferable to set the die cushion pressure so as to change linearly from the first predetermined value to the second predetermined value.

  In this case, when the die cushion pressure is changed in the third analysis procedure, it is preferable to set the die cushion pressure so that the average value of the die cushion pressure from the start of molding to the completion of molding increases.

  In this case, when the die cushion pressure is changed in the fourth analysis procedure, it is preferable to set the die cushion pressure so that the average value of the die cushion pressure from the start of molding to the completion of molding is reduced.

  In this case, when the slide speed is changed in the fifth analysis procedure, it is preferable to reduce the slide speed in the overhang forming region.

According to the present invention, the molding simulation analysis is executed and the analysis result is evaluated. If the evaluation is negative, the die cushion pressure or the slide speed is changed according to the negative cause. By repeating this process, the optimum values of both the die cushion pressure and the slide speed can be obtained with a small number of molding simulation analyses.
As a result, the number of trial productions using actual press machines and materials can be greatly reduced, and costs can be reduced. Furthermore, a product having a complicated shape can be molded by predicting molding conditions at the stage of designing the product shape.
In particular, with servo press machines and NC die cushions, the slide speed and die cushion pressure can be changed freely during molding, so a myriad of molding conditions can be set, making it difficult to find the optimum molding conditions. However, according to the present invention, the number of trial productions can be greatly reduced.

  According to the present invention, a molding simulation analysis is executed, and the analysis result is evaluated. If the evaluation is negative, the die cushion pressure or the slide speed is changed according to the negative cause. By repeating this process, the optimum values of both the die cushion pressure and the slide speed can be obtained with a small number of molding simulation analyses. As a result, the number of trial productions using actual press machines and materials can be greatly reduced, and costs can be reduced.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing a schematic configuration of a molding condition determination system 1 to which a molding condition determination method according to an embodiment of the present invention is applied. The molding condition determination system 1 includes an arithmetic processing device 10 that is connected to a press machine 30 and executes various programs, and a storage device 20 that stores information such as a hard disk.
The press machine 30 is a servo press machine driven by a servo, and the molding condition determination system 1 outputs press molding conditions including a slide speed and a die cushion pressure to the press machine 30.

  The molding condition determination system 1 includes a molding condition optimization unit 11, a molding simulation unit 12, and a press control data generation unit 13 as programs developed on an OS (Operating System) that performs operation control.

The molding simulation means 12 performs simulation analysis of the molding process. When an analysis condition is input, the molding simulation unit 12 performs a molding simulation under the analysis condition and outputs the analysis result.
The storage device 20 is a database and stores operating conditions of the press machine 30 such as a slide speed range, a slide acceleration range, and a die cushion pressure range. These operating conditions are set in advance based on the cycle time, the conveyance speed, and the like.

The molding condition optimization unit 11 sets molding conditions with reference to the operation conditions stored in the storage device 20, and outputs these molding conditions to the molding simulation unit 12 as analysis conditions. Thereafter, an analysis result is received from the molding simulation means 12, and optimum molding conditions are determined based on the analysis result.
The press control data generation unit 13 generates data for operating the press machine 30 based on the molding conditions determined by the molding condition optimization unit 11.

FIG. 2 is a diagram illustrating a schematic configuration of the press machine 30.
The press machine 30 is a so-called servo press machine, and causes the upper mold 51 to approach and separate from the lower mold mechanism 40 having the lower mold 41 disposed on the lower side of the steel plate 32 as a workpiece and the lower mold 41. An upper mold mechanism 50 and a control device 31 that controls the lower mold mechanism 40 and the upper mold mechanism 50 are provided.

  The upper mold mechanism 50 includes a servo motor 52, a reduction gear 53 that is rotationally driven by the servo motor 52, a rotary plate 54 that is rotationally driven by the reduction gear 53 with a large torque, and an upper end on the side surface of the rotary plate 54. The part has a connecting rod 55 pivotally supported.

  The servo motor 52 is, for example, an AC type, and has high responsiveness and small torque unevenness. The shaft rotation position of the servo motor 52 is detected by an encoder (not shown), and the servo motor 52 is feedback-controlled based on the detected shaft rotation position.

  The upper mold mechanism 50 further includes a slider 56 that is pivotally supported at the lower end of the connecting rod 55, and the upper mold 51 is provided on the lower surface of the slider 56.

  The upper die 51 is pressed by pressing the steel plate 32 together with the lower die 41, and a die surface 51a for contacting the upper surface of the steel plate 32 is provided on the lower surface. This 51 is a concave curved surface, and an annular holder 57 is provided around the upper mold 51. The front end surface of the holder 57 is horizontal and slightly protrudes from the mold surface 51a. Therefore, the holder 57 comes into contact with the steel plate 32 prior to the mold surface 51a.

  In addition to the lower mold 41, the lower mold mechanism 40 includes a fixed base 42 that serves as a base, an annular blank holder 43 that supports the periphery of the steel plate 32, and a die cushion mechanism 44 that raises and lowers the blank holder 43. .

  The lower die 41 is provided on the upper part of the fixed base 42 and presses the steel plate 32 together with the upper die 51. On the upper surface of the lower mold 41, a mold surface 41a for contacting the lower surface of the steel plate 32 is provided.

  The blank holder 43 is provided at a position facing the holder 57 and sandwiches the end portion of the steel plate 32 together with the holder 57 in order to prevent wrinkles and displacement when the steel plate 32 is pressed.

  The die cushion mechanism 44 includes a plurality of pins 45 that pass through the fixed base 42 and the lower mold 41 from below and support the lower portion of the blank holder 43, and a hydraulic lifting mechanism (not shown) that lifts and lowers these pins 45. .

  The lifting mechanism includes a hydraulic cylinder (not shown) connected to the pin 45 and a servo device (not shown) that drives the hydraulic cylinder. This servo device is connected to the control device 31 and performs a predetermined pressure control based on a signal from the control device 31, so that the peripheral portion of the steel plate 32 is appropriately pressured by the blank holder 43 and the holder 57. Press (die cushion pressure) to suppress wrinkles.

  The control device 31 drives the servo motor 52 to move the upper die 51 forward and backward relative to the lower die 41 and drives the die cushion mechanism 44 to raise and lower the blank holder 43.

  A procedure for drawing the steel plate 32 using the press machine 30 will be described with reference to FIG.

  First, in step S1, initial setting is performed. That is, the blank holder 43 is raised to a predetermined position, and the blank steel plate 32 is supported by the blank holder 43. Further, the upper mold 51 is raised to the top dead center. Next, in step S <b> 2, under the action of the control device 31, the servo motor 52 is rotationally driven to lower the slider 56. Hereinafter, the speed of the slider 56 is referred to as a slide speed.

  When the slider 56 is lowered to some extent, the holder 57 comes into contact with the upper surface of the steel plate 32, and the steel plate 32 is held between the holder 57 and the blank holder 43. From this point, the holder 57 is lowered under the action of the control device 31 (step S3). Specifically, under the action of the control device 31, the blank holder 43 generates an appropriate force so that the lower surface of the steel plate 32 appears to be pressed, and pressure control is performed so as to descend while securely holding the steel plate 32. . That is, the blank holder 43 is pressed through the steel plate 32 by the holder 57 and is pressed down while applying an appropriate pressure to the steel plate 32. Thereby, the steel plate 32 is lowered while the peripheral portion is held (clamped) by the holder 57 and the blank holder 43, and is gradually pressed into the product shape by the upper die 51 and the lower die 41.

  In step S4, the control device 31 causes the position of the slider 56 to reach the bottom dead center (that is, the lowest point during one stroke of the upper mold 51). In step S5, under the action of the control device 31, the servo motor 52 is rotationally driven to raise the slider 56 to the panel transport position.

  In step S6, it is confirmed whether or not the position of the slider 56 has reached the panel transport position. If it has reached, the process proceeds to step S7, and if not reached, the slider 56 continues to rise. In step S <b> 7, the blank holder 43 is raised under the action of the control device 31. As a result, the blank holder 43 rises slightly later than the slider 56.

  In step S8, the blank holder 43 is raised to the panel transport position under the action of the control device 31. In step S9, the raising of the blank holder 43 is temporarily stopped, and the steel plate 32 that has been subjected to the draw forming process is transported to the next process station by a transport means (not shown).

  In step S10, the control device 31 raises the blank holder 43 again to reach the blank holder 43 to the processing standby position. In step S11, an unprocessed steel plate is placed at a predetermined position. During this time, the slider 56 continues to rise. In step S12, the control device 31 causes the slider 56 to reach the top dead center.

Next, the displacement of the slider of the press machine 30 will be described with reference to FIG.
In the above-described draw molding, the drawing is performed by displacing the slider 56, that is, the upper die 51 as shown in FIG. Specifically, the upper mold 51 is lowered from the top dead center (X1) at a predetermined slide speed, and the speed is decreased just before the position (X2) in contact with the steel sheet. Then, press molding is performed while increasing the speed. When the upper mold 51 reaches the bottom dead center (X0), the upper mold 51 is raised at the original slide speed (predetermined speed).

Returning to FIG. 1, the molding condition optimization unit 11 includes a molding condition setting unit 60 and an analysis result evaluation unit 61.
The molding condition setting unit 60 refers to the operation conditions stored in the storage device 20 and sets the molding conditions including the slide speed and the die cushion pressure. Further, the control parameters of the slide speed and the die cushion pressure are increased according to the analysis result of the analysis result evaluation means 61.

Based on the result of the molding simulation analysis performed by the molding simulation unit 12, the analysis result evaluation unit 61 determines whether the quality of the press-formed product reaches a certain standard.
Specifically, the maximum value of the plate thickness reduction rate and the minimum principal strain are used as an index for evaluating the molded product.

That is, when the plate thickness reduction rate becomes large, cracks are likely to occur, so it is determined whether or not the maximum value of the plate thickness reduction rate is a predetermined value or less. If this determination is NO, it is determined that a crack has occurred and the quality of the press-formed product has not reached a certain standard.
Further, when it is determined that a crack is generated, it is determined whether a crack is generated in the drawing region of the press-formed product or a crack is generated in the overhang region of the press-formed product. Whether the molded part is the drawn region or the overhang region is determined by the sign of the minimum principal strain.If the minimum principal strain is negative, a crack occurs in the drawn region and the minimum principal strain is reduced. If it is positive, it is determined that a crack occurs in the aperture region.

  In addition, if the minimum principal distortion is small, wrinkles and surface distortion are likely to occur. Therefore, it is determined whether or not the minimum principal distortion is greater than or equal to a predetermined value. If this determination is NO, it is determined that wrinkles have occurred and the quality of the press-formed product has not reached a certain standard.

  The molding condition optimization unit 11 operates the molding condition setting unit 60, the molding simulation unit 12, and the analysis result evaluation unit 61 in this order. With this series of operations as one analysis cycle, the molding condition optimization means 11 determines that the quality of the press-formed product reaches a certain standard by the analysis result evaluation means 63 or the number of loops reaches a predetermined number. Repeat the analysis cycle until

Next, the operation of the molding condition optimizing means 11 will be described with reference to the flowcharts of FIGS.
First, in step S11, the molding condition setting means 60 maximizes the slide speed as an initial condition and the die cushion pressure during molding is constant, and the molding simulation means 12 performs molding simulation analysis.
For example, as shown in FIG. 7, the die cushion pressure at the molding start time t ₁ and the molding completion time t ₂ is set to a constant value P ₀ .

  As described above, in step S11, one control parameter is set for the die cushion pressure, but in the actual molding simulation analysis, the analysis is performed by setting at least three values for each control parameter.

In step S12, the analysis result evaluation unit 61 determines whether the maximum value of the plate thickness reduction rate is equal to or less than a predetermined value. If this determination is YES, the process proceeds to step S13, and if this determination is NO, the process proceeds to step S14.
In step S13, the analysis result evaluation unit 61 determines whether or not the minimum principal distortion is greater than or equal to a predetermined value. If this determination is YES, the current molding condition is output as the optimum condition and the process ends. If NO, the process proceeds to step S14.
In step S14, a counter k indicating the number of loops is set to 1.

In step S15, the molding condition setting means 60 sets the die cushion pressure at the start of molding and the die cushion pressure at the completion of molding, and the molding simulation means 12 performs molding simulation analysis.
For example, as shown in FIG. 8, a die cushion pressure molding start time t ₁ P _1, the die cushion pressure of the forming completion time t ₂ is set to a low P ₂ than P _1, the die cushion pressure P ₁ To P _{2 in a} linear manner.

  As described above, in step S15, two control parameters for the die cushion pressure at the start of molding and at the end of molding are set. In actual molding simulation analysis, at least three values are set for each control parameter. To analyze.

In step S16, the analysis result evaluation means 61 determines whether or not the maximum value of the plate thickness reduction rate is equal to or less than a predetermined value. If this determination is YES, the process proceeds to step S17, and if NO, the process proceeds to step S18.
In step S17, the analysis result evaluation unit 61 determines whether or not the minimum principal distortion is equal to or greater than a predetermined value. If this determination is YES, the current molding condition is output as the optimum condition, and the process ends. If NO, the process proceeds to step S21.

  In step S18, since it is determined that the maximum value of the plate thickness reduction rate is equal to or less than the predetermined value, the forming condition generation unit 60 determines whether or not the portion where the plate thickness reduction rate is the maximum is the draw forming region. . If this determination is YES, the process proceeds to step S19, and if NO, the process proceeds to step S20.

In step S19, cracks are considered to occur in the drawing region, that is, the portion formed by the inflow of the material. And the molding simulation analysis is executed by the molding simulation means 12.
For example, as shown in FIG. 9, the control point C ₁ is the die cushion pressure P _3, which is an intermediate time t ₃ between the molding start time t ₁ and the molding completion time t ₁ so that the average value of the die cushion pressure decreases. Add Then, from time _{t 1} to time _{t 3,} the die cushion pressure is changed linearly from _{P 1} to _{P 3,} from time _{t 3} to time _{t 2, the} linearly changing the die cushion pressure from _{P 3} to _{P 2} Let

Thus, in step S19, the pressure and time, but be added as two control parameter representing the control point C ₁ of the die cushion pressure, in the actual molding simulation analysis, for each control parameter one, at least three values Set to to perform analysis.

In step S20, cracks are considered to occur in the overmolding region, that is, the portion formed by the extension of the material. Then, a molding simulation analysis is executed by the molding simulation means 12.
For example, as shown in FIG. 10, the sliding speed of the stretch forming region so as to reduce, to add control points S _1. Thereby, the molding completion time is changed from time t ₂ to time t ₂ ′.

Thus, in step S20, the location and time of the slider, but be added as two control parameter representing the control point S ₁ of the slider, in the actual molding simulation analysis, for each control parameter one, at least three values Set to to perform analysis.

In step S21, the molding condition setting unit 60 adds a control point of the die cushion pressure so that the average value of the die cushion pressure increases, and the molding simulation unit 12 executes the molding simulation analysis.
For example, as shown in FIG. 11, a control point C ₂ that is an intermediate time t ₃ between the molding start time t ₁ and the molding completion time t ₁ and the die cushion pressure P ₄ so that the average value of the die cushion pressure increases. Add From time _{t 1} to time _{t 3,} the die cushion pressure is varied linearly with _{P 4} from _{P 1,} from time _{t 3} to time _{t 2, the} changing of the die cushion pressure linearly from _{P 4} to _{P 2.}

Thus, in step S19, the pressure and time, but be added as two control parameter representing the control point C ₁ of the die cushion pressure, in the actual molding simulation analysis, for each control parameter one, at least three values Set to to perform analysis.

In step S22, the analysis result evaluation unit 61 determines whether or not the maximum value of the plate thickness reduction rate is equal to or less than a predetermined value. If this determination is YES, the process proceeds to step S23, and if this determination is NO, the process proceeds to step S24.
In step S23, the analysis result evaluation unit 61 determines whether or not the minimum principal distortion is greater than or equal to a predetermined value. If this determination is YES, the current molding condition is output as the optimum condition, and the process ends. If NO, the process proceeds to step S25.

In step S24, it is determined whether or not the value of the counter k is a predetermined value. If this determination is YES, since the number of loops has reached a predetermined number, the current molding condition is output as the optimum condition, and the process ends. If NO, the process returns to step S18.
In step S25, it is determined whether or not the value of the counter k is a predetermined value. If this determination is YES, since the number of loops has reached a predetermined number, the present molding condition is output as the optimum condition, and the process ends. If NO, the process returns to step S21.

  As described above, the molding condition optimizing unit 11 increases the control parameter related to the die cushion pressure or the slide speed until the result of the molding simulation analysis becomes affirmative or the number of loops reaches a predetermined number.

According to this embodiment, there are the following effects.
(1) A molding simulation analysis is executed by the molding simulation means 12, and the analysis result evaluation means 61 evaluates this analysis result. If the evaluation is negative, the die cushion pressure or the slide speed is changed by the molding condition setting means 60 according to the negative cause. By repeating this process, the optimum values of both the die cushion pressure and the slide speed can be obtained with a small number of molding simulation analyses.
As a result, the number of trial productions using actual press machines and materials can be greatly reduced, and costs can be reduced. Furthermore, a product having a complicated shape can be molded by predicting molding conditions at the stage of designing the product shape.
In particular, with the servo press machine 30 and the NC die cushion, the slide speed and die cushion pressure can be freely changed during molding, so numerous molding conditions can be set, and it is difficult to find optimal molding conditions. However, according to the present invention, the number of prototypes can be greatly reduced.

It should be noted that the present invention is not limited to the above-described embodiment, and modifications, improvements, etc. within a scope that can achieve the object of the present invention are included in the present invention.
For example, in the present embodiment, it is determined whether or not a crack is generated using the maximum value of the plate thickness reduction rate, but not limited to this, whether or not a crack is generated using an equivalent plastic strain. You may judge. This is because cracks tend to occur when the equivalent plastic strain increases. Therefore, specifically, it is determined whether or not the maximum value of the equivalent plastic strain is equal to or less than a predetermined value. If this determination is Yes, it is determined that no cracks occur. Is determined to occur.

It is a figure which shows schematic structure of the molding condition determination system to which the molding condition determination method which concerns on one Embodiment of this invention is applied. It is a figure which shows schematic structure of the press of the molding condition determination system which concerns on the said embodiment. It is a flowchart which shows the process sequence of the press machine which concerns on the said embodiment. It is a figure which shows the relationship between the slider position of the press which concerns on the said embodiment, and molding time. It is a flowchart (the 1) which shows operation | movement of the press of the molding condition determination system which concerns on the said embodiment. It is a flowchart (the 2) which shows operation | movement of the press of the molding condition determination system which concerns on the said embodiment. It is a figure which shows the state which set the die cushion pressure of the press machine which concerns on the said embodiment fixed. It is a figure which shows the state which set the die cushion pressure of the shaping | molding start time and shaping | molding completion time of the press which concerns on the said embodiment. It is a figure which shows the state which added the control point so that the average value of die-cushion pressure of the press concerning the said embodiment may fall. It is a figure which shows the state which added the control point so that the slide speed of the press concerning the said embodiment may fall. It is a figure which shows the state which added the control point so that the average value of die-cushion pressure of the press concerning the said embodiment may rise.

Explanation of symbols

S11 to S13 First analysis procedure S14 to S17 Second analysis procedure S21 to S23 Third analysis procedure S18, S19, S22, S23 Fourth analysis procedure S18, S20, S22, S23 Fifth analysis procedure

Claims (6)

A molding condition determination method for determining molding conditions of a press machine,
A molding simulation analysis is executed under initial conditions, and the result of the molding simulation analysis is evaluated. If the evaluation is affirmative, a first analysis procedure that sets the molding conditions of the molding simulation analysis as an optimum value;
When the evaluation of the first analysis procedure is negative, the die cushion pressure is changed to execute the molding simulation analysis, the result of the molding simulation analysis is evaluated, and when the evaluation is positive , A second analysis procedure in which the molding conditions of this molding simulation analysis are the optimum values,
If the evaluation of the second analysis procedure is negative due to the occurrence of wrinkles, the die simulation pressure is changed, the molding simulation analysis is executed, the result of the molding simulation analysis is evaluated, and the evaluation is positive A third analysis procedure in which the molding conditions of this molding simulation analysis are set to optimum values,
If the evaluation of the second analysis procedure is negative due to the occurrence of cracks in the draw forming region, the die simulation pressure is changed to execute the molding simulation analysis, and the result of the molding simulation analysis is evaluated. If the evaluation is affirmative, a fourth analysis procedure in which the molding conditions of the current molding simulation analysis are set to optimum values;
When the evaluation of the second analysis procedure is negative due to the occurrence of cracks in the overhang forming region, the forming simulation analysis is performed by changing the slide speed, the result of the forming simulation analysis is evaluated, If the evaluation is affirmative, it comprises a fifth analysis procedure in which the molding conditions of the molding simulation analysis in the second analysis procedure are the optimum values,
When the evaluation of the third, fourth, and fifth analysis procedures is negative due to the occurrence of wrinkles, the process returns to the third analysis procedure, and is negative due to the occurrence of cracks in the drawing region The method returns to the third analysis procedure and returns to the fifth analysis procedure if the result is negative due to the occurrence of a crack in the overhang forming region. In the molding condition determination method according to claim 1,
The molding condition determination method according to claim 1, wherein the initial condition of the first analysis procedure includes that the slide speed is maximum and the die cushion pressure is constant. In the molding condition determination method according to claim 1 or 2,
When the die cushion pressure is changed in the second analysis procedure, the die cushion pressure at the start of molding is set as a first predetermined value, and the die cushion pressure at the time of molding is set as a second predetermined value. 2. A molding condition determining method, wherein the die cushion pressure is set so as to change linearly up to a predetermined value. In the molding condition determination method according to any one of claims 1 to 3,
A molding condition determining method, wherein when the die cushion pressure is changed in the third analysis procedure, the die cushion pressure is set so that an average value of the die cushion pressure from the start of molding to the completion of molding is increased . In the molding condition determination method according to any one of claims 1 to 4,
When the die cushion pressure is changed in the fourth analysis procedure, the die cushion pressure is set so that the average value of the die cushion pressure from the start of molding to the completion of molding is reduced . In the molding condition determination method according to any one of claims 1 to 5,
A molding condition determination method characterized by slowing the slide speed in the overhang forming area when the slide speed is changed in the fifth analysis procedure.

Images