JP2008149356A - Method and apparatus for designing highly rigid component, computer program, and computer readable recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To present an optimal press forming condition in order to obtain a desired natural frequency and deformation mode in a component being a final product in consideration of effects of a change in the plate thickness and hardening caused by plastic working in manufacturing a formed article. <P>SOLUTION: In a method for designing a highly rigid component, a computer performs a press forming analysis based on press forming conditions such as a shape of the formed article, amount of punch movement, loading for wrinkle pressing, friction coefficient, relation between stress and strain of material, and plate thickness, to calculate the distribution of the plate thickness of the formed article; and also performs a dynamic stiffness analysis based on conditions for a dynamic stiffness analysis such as the distribution of the plate thickness of the formed article and a component shape manufactured by assembling the formed article, to calculate the natural frequency. In the method, the computer repeats the calculation predetermined times while changing at least one or more of the press forming conditions, and outputs the maximum value of the natural frequency or the press forming condition providing a stable region as the optimal press forming condition. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for designing a member having high rigidity, which is a member manufactured by assembling press molding used in automobiles, electrical products, and the like, a computer program, and a computer-readable recording medium.

  Devices that generate vibration, such as automobiles and electrical products, are required to have high rigidity for the components that make up the device in order to prevent deformation of the device against external forces and to prevent vibration and sound propagation. . A member having high rigidity generally has a high natural frequency. In the conventional design of equipment component members, after determining an initial shape, dynamic rigidity analysis is performed by a method such as a finite element method, and the shape of the member is changed so that the natural frequency and the deformation mode become target values. After the evaluation by analysis achieves the target value, final confirmation is made by trial manufacture and experiment, and the design is confirmed.

  These members are manufactured by plastically processing a thin plate, tube or rod of steel or other material to form a molded product, and then joining with other materials as necessary. For the plastic working, a forming method such as pressing, hydroforming or extrusion is used. For the joining, methods such as spot welding, arc welding, laser welding or rivet joining, bolt joining, and caulking are used.

  Conventionally, as shown in FIG. 7, a technique called coupled analysis from press forming analysis to collision analysis is known. In FIG. 7, 10 is a material before processing, 11 is a result of press forming analysis, 12 is a result of converting the result of press forming analysis into input data of collision analysis, and 13 is a result of collision analysis. In Patent Document 1, forming analysis is performed after the added shape data is created based on the final part shape data of the pressed part, and characteristic analysis such as collision resistance performance is coupled based on the obtained analysis result. A simulation method is disclosed. However, Patent Document 1 does not describe a method for presenting an optimal part shape and molding conditions.

  Further, in Patent Document 2, in order to design steel products such as automobile parts using a computer, a step of storing material parameters to be used in advance and at least a material standard, plate thickness, and shape of the steel product are stored. A step of evaluating the formability, rigidity, and strength of the steel product, and if not satisfying at least one of the required specifications of the formability, rigidity, and strength, A design method and a design system including a step of correcting at least one of thickness and shape and a step of reevaluating the formability, rigidity, and strength are disclosed. That is, in the method disclosed in Patent Document 2, after evaluating the formability of a steel product by forming CAE (Computer Aided Engineering), rigidity CAE and strength CAE are individually performed until the required specifications regarding rigidity and strength are satisfied. It is a system for correcting the material standard, plate thickness, and shape of the steel product. However, if a defect such as cracking occurs in the molding CAE, there is a description of the step of changing the molding conditions and re-evaluating, but the optimum molding processing conditions to satisfy the final required characteristics (rigidity, strength) are described. There is no description about the method of presentation.

JP 2004-50253 A JP 2002-297670 A

  When a metal such as steel is used as a material, changes in the plate thickness due to plastic working during the production of the molded product or work hardening due to plastic strain occur, and the molded product has an external force compared to when there is no plate thickness change or work hardening. It is known that the natural frequency and deformation mode change when subjected to vibration. At present, when the dynamic rigidity analysis such as the finite element method is not taken into account in the member after assembling these molded products into the final product, it is designed with the evaluation value of the analysis because the plate thickness change and work hardening are not considered. However, the desired natural frequency and deformation mode cannot be obtained in trial production and experiment. In addition, due to variations in plastic working conditions at the time of manufacturing a molded product, variations in plate thickness change and work hardening also occur, and eventually the natural frequency and deformation mode of the member vary.

  In the present invention, optimum press molding conditions are set in order to obtain a desired natural frequency and deformation mode in a member that is a final product, while taking into consideration the influence of plate thickness change and work hardening due to plastic working during the production of a molded product. The purpose is to be able to present. Design parameters include the material, plate thickness, shape, processing conditions, welding conditions, etc. of the molded product.

In order to solve this problem, the gist of the present invention is as follows.
(1) As the press molding conditions, the computer performs press molding analysis based on the molded product shape, punch travel, wrinkle press load, friction coefficient, material stress-strain relationship, and plate thickness, and the thickness distribution of the molded product is determined. Calculating the natural frequency based on the plate thickness distribution of the molded product and the shape of the member manufactured by assembling the molded product, and calculating the natural frequency as the dynamic stiffness analysis condition. At least one or more of the conditions are changed, the computer repeatedly performs a predetermined number of calculations, and the press molding condition that gives the maximum value or stable region of the natural frequency is output as the optimum press molding condition. Design method for high parts.
(2) Press molding condition input means for inputting a molded product shape, punch movement amount, wrinkle press load, friction coefficient, material stress-strain relationship, and plate thickness as press molding conditions;
Performs press molding analysis based on the molded product shape, punch movement amount, wrinkle presser load, friction coefficient, material stress-strain relationship, and plate thickness input to the press molding condition input means, and plate thickness distribution of the molded product Press forming analysis means for calculating
Dynamic stiffness analysis condition input means for inputting the plate thickness distribution of the molded product calculated by the press molding analysis means and a member shape manufactured by assembling the molded product as dynamic stiffness analysis conditions;
Dynamic stiffness analysis means for performing dynamic stiffness analysis based on the plate thickness distribution of the press-formed product input to the dynamic stiffness analysis condition input means and the shape of a member manufactured by assembling the molded product and calculating the natural frequency When,
By changing at least one of the press molding conditions, the calculation by the press molding condition input means, the press molding analysis means, the dynamic stiffness analysis condition input means, and the dynamic stiffness analysis means is automatically performed a predetermined number of times. Repetitive calculation control means to be executed;
An apparatus for designing a highly rigid member, comprising: an optimum press molding condition output unit that outputs a press molding condition that gives a maximum value or a stable region of the natural frequency as an optimum press molding condition.
(3) Press molding analysis is performed based on the molded product shape, punch travel, wrinkle press load, friction coefficient, material stress-strain relationship, and plate thickness as the press molding conditions, and the plate thickness distribution of the molded product is calculated. Performing the dynamic stiffness analysis based on the thickness distribution of the molded product as a dynamic stiffness analysis condition and the shape of a member manufactured by assembling the molded product, and calculating the natural frequency at least of the press molding conditions A computer program that causes a computer to execute a process of repeatedly calculating a predetermined number of times by changing one or more types, and outputting a press molding condition that gives a maximum value or a stable region of the natural frequency as an optimum press molding condition .
(4) A computer-readable recording medium on which the computer program of (3) is recorded.
In the present invention, the “molded product” refers to an intermediate product after molding, and an assembly of the “molded product” is defined as a “member”, that is, a final product.

  According to the present invention, the natural frequency when an external force or vibration is applied is set to a desired value while considering the influence of the plate thickness change and work hardening at the time of manufacturing the molded product, and the processing conditions at the time of manufacturing the molded product Even when there is a variation, it is possible to design optimum press molding conditions in order to obtain a member whose natural frequency does not vary greatly.

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.
FIG. 1 is a flowchart for explaining a method for designing a highly rigid member to which the present invention is applied.

  (1). As the press molding conditions, the molded product shape, punch movement amount, wrinkle presser load, friction coefficient, material stress-strain relationship, and plate thickness are set as molding analysis input data 1.

  (2). Based on the molding analysis input data 1, the computer performs press molding analysis by the molding analysis program 2, calculates and outputs the plate thickness distribution of the molded product as molding analysis output data 3, and this is converted by the input conversion program 4. Convert to stiffness analysis input data 5.

  (3). Based on the plate thickness distribution of the molded product as a dynamic stiffness analysis condition and the shape of a member manufactured by assembling the molded product, the computer performs a dynamic stiffness analysis by the dynamic stiffness analysis program 6 and is inherent as dynamic stiffness analysis output data 7 The frequency is calculated and output, and whether or not the rigidity performance is satisfied in step 8 is evaluated. In this case, members are assembled on the computer based on the molded product.

  (4). When the rigidity performance is not a desired value, or when the steps 1 to 7 are less than the predetermined number of times, at least one of the press molding conditions (molding analysis input data) 1 is changed, and the computer Will repeat the steps from 1 to 7 a predetermined number of times.

  (5). The steps 1 to 7 are repeatedly calculated and evaluated in step 8, and when the rigidity performance reaches a desired value, the optimum press molding condition 9 is output, and the flow ends. Thereby, the optimal press molding conditions (processing conditions) 9 which give the maximum value or stable region of a natural frequency can be obtained.

  The molding analysis / dynamic stiffness analysis may be a commercially available analysis program such as a finite element method or a self-made program. In addition, data conversion from molding analysis to dynamic stiffness analysis, stiffness performance evaluation, and shape / machining condition change are also performed by a commercially available program or a self-made program.

  FIG. 2 is a block diagram showing a configuration example of a computer system that functions as the design apparatus of the present invention. In the figure, reference numeral 1200 denotes a computer PC. The PC 1200 includes a CPU 1201, executes device control software stored in the ROM 1202 or the hard disk (HD) 1211, or supplied from the flexible disk drive (FD) 1212, and collects all devices connected to the system bus 1204. To control. Each functional unit of the present embodiment is configured by a program stored in the CPU 1201 of the PC 1200, the ROM 1202, or the hard disk (HD) 1211.

  Reference numeral 1203 denotes a RAM which functions as a main memory, work area, and the like for the CPU 1201. Reference numeral 1205 denotes a keyboard controller (KBC), which controls to input a signal input from the keyboard (KB) 1209 into the system main body. Reference numeral 1206 denotes a display controller (CRTC) which performs display control on the display device (CRT) 1210. A disk controller (DKC) 1207 is a hard disk that stores a boot program (startup program: a program for starting execution (operation) of hardware and software of a personal computer), a plurality of applications, editing files, user files, a network management program, and the like. Controls access to the (HD) 1211 and the flexible disk (FD) 1212. Reference numeral 1208 denotes a network interface card (NIC) that performs bidirectional data exchange with a network printer, another network device, or another PC via the LAN 1220.

  Note that the welding condition setting device of the present invention may be applied to a system composed of a plurality of devices or an apparatus composed of a single device.

  Another object of the present invention is to supply a storage medium storing software program codes for realizing the functions of the above-described embodiments to a system or apparatus, and store the computer (CPU or MPU) of the system or apparatus in the recording medium. Needless to say, this can also be achieved by reading and executing the programmed program code. In this case, the program code itself read from the recording medium realizes the functions of the above-described embodiments, and the recording medium on which the program code is recorded constitutes the present invention. As a recording medium for supplying the program code, for example, a flexible disk, hard disk, optical disk, magneto-optical disk, CD-ROM, CD-R, magnetic tape, nonvolatile memory card, ROM, or the like can be used.

(Example)
Examples of the present invention are shown below.
1. Design Object As this embodiment, as shown in FIG. 4, optimum molding conditions for a member in which a contact plate is spot-welded to a hat-shaped cross-sectional member are designed. The hat-shaped cross-sectional member is formed by pressing. The member is unconstrained, and the pressing process condition (wrinkle presser load = BHF) is optimized so that the natural frequency at this time is maximized.

  The dimensions of the hat-shaped cross-sectional member are a length of 300 mm, a cross-sectional width of 50 mm, a cross-sectional height of 50 mm, a flange width of 10 mm, and a plate thickness of 1.42 mm. The dimensions of the contact plate are 300 mm in length, 90 mm in width, and 1.165 mm in plate thickness. The material is a high-tensile steel plate with a tensile strength of 590 MPa for both the hat-shaped cross-section member and the backing plate, and the stress-strain relationship is as shown in FIG.

  As other press molding conditions, the punch movement amount = 50 mm, the initial wrinkle press load (BHF) is 40 kN, and the friction coefficient = 0.15.

2. Molding analysis The press molding conditions were input and a commercially available finite element analysis program Hyper Form was used. Press molding analysis was performed to calculate the thickness distribution of the molded product shown in FIG.

3. Data conversion Input data from the analysis result of molded product thickness distribution by molding analysis to dynamic stiffness analysis is created and used by FORTRAN program, and the thickness distribution and member shape of molded product are input as dynamic stiffness analysis conditions. did.

4). Dynamic stiffness analysis Dynamic stiffness analysis was performed using a commercially available finite element analysis program Nastran. The natural frequencies from the first to the fifth order were calculated as shown in FIG. 4 including the case where the press molding conditions described later were changed.

5. Rigid performance evaluation / processing condition change A commercially available optimization tool iSIGHT was used. The wrinkle presser load is changed in the range of 4 to 200 kN in the above press forming conditions so that the natural frequency becomes maximum and stable, and the process from 1 to 7 in FIG. The optimum press forming condition that gives the maximum value or stable region of the frequency was searched.

6). Results FIG. 6 shows the results. In the graph, the horizontal axis represents the wrinkle presser load, and the vertical axis represents the square root of the square sum of the natural frequencies of each order. From this characteristic diagram, the point 14 where the natural frequency is maximum is when the wrinkle presser load = 4 kN, and the natural frequency is 697 Hz. However, under this condition, the wrinkle presser load is the lower limit of the device restriction, and it is difficult to adopt it as the optimum design point from the viewpoint of industrial production. In addition, when the wrinkle presser load varies, the natural frequency is also affected.

  At this time, as the range 15 in which the natural frequency is highly stable, there is a range of wrinkle presser load = 50 to 70 kN, and this intermediate point may be adopted as the optimum design point.

  That is, as an optimum press molding condition, a member in which a contact plate is spot-welded to a hat-shaped cross-section member that has been press-molded under the condition that the wrinkle press load is 60 ± 10 kN is created, When the dynamic stiffness test was conducted, it was confirmed that the square root of the square sum of the natural frequencies from the first to the fifth order was 697 Hz, and a dynamic stiffness exceeding the target (690 Hz or more) was obtained.

It is a flowchart for demonstrating the design method of a highly rigid member to which this invention is applied. It is a figure which shows the structural example of the computer system which functions as a design apparatus of the highly rigid member of this invention. It is a figure which shows the plate | board thickness distribution of the molded article in an Example. It is a figure for demonstrating the dynamic rigidity analysis in an Example. It is a characteristic view which shows the stress-strain relationship of the material in an Example. It is a figure which shows the result in an Example, and a horizontal axis | shaft is a wrinkle presser load, and a vertical axis | shaft is a characteristic figure which is the square root of the square sum of the natural frequency of each order. It is a figure for demonstrating the conventional coupled analysis of shaping | molding and dynamic rigidity.

Explanation of symbols

1. Forming analysis input data such as member shape and processing conditions 2. Program for performing forming analysis 3. Plate thickness distribution obtained by forming analysis 4. Program for converting output data of forming analysis into input data for dynamic stiffness analysis 5. Member shape, forming Stiffness analysis input data 6 such as plate thickness distribution based on 7 Stiffness analysis such as natural frequency obtained by dynamic stiffness analysis 8 Optimization program to evaluate rigidity performance and change molding analysis input data 9 Optimal machining conditions obtained by the optimum design system 10 Material before machining 11 Result of molding analysis 12 Result of molding analysis converted to input data of collision analysis 13 Result of collision analysis 14 Natural frequency is maximized Point 15 Range in which natural frequency is highly stable

Claims (4)

  As the press molding conditions, the computer performs press molding analysis based on the molded product shape, punch travel, wrinkle press load, friction coefficient, material stress-strain relationship, and plate thickness, and calculates the plate thickness distribution of the molded product, The computer performs dynamic stiffness analysis based on the plate thickness distribution of the molded product as a dynamic stiffness analysis condition and the shape of a member manufactured by assembling the molded product, and calculates the natural frequency. A highly rigid member characterized in that at least one kind is changed, a computer repeatedly performs a predetermined number of calculations, and a press molding condition that gives a maximum value or a stable region of the natural frequency is output as an optimal press molding condition. Design method. Press molding condition input means for inputting the molded product shape, punch movement amount, wrinkle presser load, friction coefficient, material stress-strain relationship, and plate thickness as press molding conditions;
Performs press molding analysis based on the molded product shape, punch movement amount, wrinkle presser load, friction coefficient, material stress-strain relationship, and plate thickness input to the press molding condition input means, and plate thickness distribution of the molded product Press forming analysis means for calculating
Dynamic stiffness analysis condition input means for inputting the plate thickness distribution of the molded product calculated by the press molding analysis means and a member shape manufactured by assembling the molded product as dynamic stiffness analysis conditions;
Dynamic stiffness analysis means for performing dynamic stiffness analysis based on the plate thickness distribution of the press-formed product input to the dynamic stiffness analysis condition input means and the shape of a member manufactured by assembling the molded product and calculating the natural frequency When,
By changing at least one of the press molding conditions, the calculation by the press molding condition input means, the press molding analysis means, the dynamic stiffness analysis condition input means, and the dynamic stiffness analysis means is automatically performed a predetermined number of times. Repetitive calculation control means to be executed;
An apparatus for designing a highly rigid member, comprising: an optimum press molding condition output unit that outputs a press molding condition that gives a maximum value or a stable region of the natural frequency as an optimum press molding condition.   Press molding analysis is performed based on the molded product shape, punch travel, wrinkle presser load, friction coefficient, material stress-strain relationship, and plate thickness as the press molding conditions, and the plate thickness distribution of the molded product is calculated to determine the dynamic stiffness. At least one of the press molding conditions is a step of performing dynamic stiffness analysis based on the plate thickness distribution of the molded product and the shape of a member manufactured by assembling the molded product as an analysis condition, and calculating a natural frequency. A computer program that causes a computer to execute a process of repeatedly calculating a predetermined number of times and outputting a press molding condition that gives a maximum value or a stable region of the natural frequency as an optimum press molding condition.   A computer-readable recording medium on which the computer program according to claim 3 is recorded.

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