CN109127945B - Method for regulating and controlling stamping forming precision of lightweight car body covering part - Google Patents
Method for regulating and controlling stamping forming precision of lightweight car body covering part Download PDFInfo
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- CN109127945B CN109127945B CN201810863964.7A CN201810863964A CN109127945B CN 109127945 B CN109127945 B CN 109127945B CN 201810863964 A CN201810863964 A CN 201810863964A CN 109127945 B CN109127945 B CN 109127945B
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- 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
- B21D53/00—Making other particular articles
- B21D53/88—Making other particular articles other parts for vehicles, e.g. cowlings, mudguards
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F30/00—Computer-aided design [CAD]
- G06F30/10—Geometric CAD
- G06F30/15—Vehicle, aircraft or watercraft design
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F30/00—Computer-aided design [CAD]
- G06F30/10—Geometric CAD
- G06F30/17—Mechanical parametric or variational design
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Abstract
The invention relates to a method for regulating and controlling stamping forming precision of a lightweight car body covering part, which comprises the following steps of: s1, completing the multi-process forming modeling and the springback process simulation of the automobile body covering part; s2, establishing an accuracy transfer model considering deformation and springback of each intermediate process: subtracting the rebound quantity of the nth procedure from the rebound quantity of the (n + 1) th procedure to obtain the influence of the (n + 1) th procedure on the rebound quantity; and S3, calculating the springback amount of each process at any position on the surface of the covering part based on the precision transfer model, and compensating the mould surface according to the calculated springback amount so as to realize springback control. The invention comprehensively considers the influence of demoulding stress release between the working procedures on the forming and the precision, adds the springback simulation after each working procedure, takes the shape of the part rebounded by each working procedure as the input of the next working procedure, thereby completing the multi-working-procedure forming and springback simulation of the covering part, and accurately controlling the stamping precision of the covering part based on the established multi-working-procedure precision transfer model.
Description
Technical Field
The invention relates to the technical field of stamping, in particular to a method for regulating and controlling stamping forming precision of a lightweight automobile body covering part.
Background
The sheet metal stamping forming process can generate different types of defects such as cracking, wrinkling and springback, wherein the springback is inevitable, and the springback is particularly obvious in the cold forming process of the light-weight high-strength sheet metal. Since the rebound can seriously affect the dimensional accuracy of a formed part, the rebound is usually controlled within a reasonable range as much as possible through process and die adjustment in engineering.
On the other hand, for the automobile body covering parts with large size and complex shape, the stamping process is often completed by combining a plurality of processes, including drawing, trimming, flanging, punching, shaping and the like. For each working procedure, the plate material completes corresponding deformation under the action of the forming force of the die, and then the plate material is unloaded to enter the next working procedure. During unloading, the sheet material can rebound due to the release of the elastic stress in the sheet material. Therefore, the accuracy of all the working procedures is mutually influenced, so that the stamping rebound of the automobile body covering part is difficult to predict, and the accuracy regulation and control difficulty is extremely high.
The springback is predicted by adopting a finite element method, so that the die repairing times and the die repairing quantity can be reduced, the cost is saved, and the period is shortened. The existing method for simulating the finite element of the multi-process stamping springback of the automobile body covering part does not consider the release of demoulding stress among all the processes, so that the springback prediction precision is low, and the difference from the actual production condition of a product is large.
Disclosure of Invention
The invention aims to provide a method for regulating and controlling the stamping forming precision of a lightweight car body covering part, and solves the problems of low prediction precision, difficult springback control and the like of multi-process stamping forming of the car body covering part.
The technical scheme adopted by the invention for solving the technical problems is as follows: a regulation and control method for stamping forming precision of a lightweight car body covering part is constructed, and comprises the following steps:
s1, completing the multi-process forming modeling and the springback process simulation of the automobile body covering part;
s2, establishing an accuracy transfer model considering deformation and springback of each intermediate process: comparing the profile before rebounding of the nth process with the profile of the workpiece rebounded by the nth process to obtain the rebound quantity of the nth process:
s(x,y)＝∑pijxiyj
wherein s is the rebound quantity, x and y are respectively the horizontal and vertical coordinates of the covering part, and pijI and j are any values in the range of 0-9;
the influence of the rebound amount in the n +1 th step, i.e., the difference Δ s between the rebound amounts in the n +1 th step is found by subtracting the rebound amount in the n +1 th step from the rebound amount in the n +1 th stepn+1-sn；
And S3, calculating the springback amount of each process at any position on the surface of the covering part based on the precision transfer model, and compensating the mould surface according to the calculated springback amount so as to realize springback control.
In the scheme, the step S1 further comprises the steps of ① determining the process flow of the covering part by combining the structural characteristics and the material characteristics of the covering part, ② establishing forming dies of each process of the covering part through CAD and CAE software, taking the drawing process as an example, firstly carrying out geometric cleaning on the molded surface of the part, determining the optimal stamping direction, and designing a material pressing surface and a process supplement surface so as to finish the design of the drawing die, ③ determining the optimal process parameters of each process on the basis of an optimization algorithm, wherein the optimal process parameters comprise a tool friction coefficient, a die clearance, a blank holder pressure, a stamping speed, a drawing rib resistance and the like, ④ establishing a multi-process forming simulation model of the covering part on the basis of the CAE software, increasing rebound simulation after each process, finishing the multi-process forming simulation of;
in the scheme, if the delta s is greater than 0, the rebound is positive, which indicates that the (n + 1) th process has a positive effect on the increase of the rebound amount; if deltas is 0, the rebound is zero, which shows that the n +1 st procedure has no influence on the increase of the rebound amount; if deltas is less than 0, the rebound is negative, which indicates that the n +1 process has negative effect on the increase of the rebound amount.
The method for regulating and controlling the stamping forming precision of the lightweight car body covering part has the following beneficial effects:
the invention comprehensively considers the influence of demoulding stress release between the working procedures on the forming and the precision, adds the springback simulation after each working procedure, takes the shape of the part rebounded by each working procedure as the input of the next working procedure, thereby completing the multi-working-procedure forming and springback simulation of the covering part, and accurately controlling the stamping precision of the covering part based on the established multi-working-procedure precision transfer model.
Drawings
The invention will be further described with reference to the accompanying drawings and examples, in which:
FIG. 1 is a top view of a truck cab;
FIG. 2 is a numerical simulation method for multi-step forming of a cover part according to the present invention;
fig. 3a-c show the forming die for each process of the ceiling: FIG. 3a is a drawing process, FIG. 3b is a trimming and punching contour line, and FIG. 3c is a flanging process;
4a-c are cloud charts of resilience values of various procedures of the ceiling: FIG. 4a is a drawing process, FIG. 4b is a trimming process, and FIG. 4c is a flanging and punching process;
FIG. 5 is a cloud of part spring back after mold surface compensation.
Detailed Description
For a more clear understanding of the technical features, objects and effects of the present invention, embodiments of the present invention will now be described in detail with reference to the accompanying drawings.
As shown in fig. 1-5, a 1.5mm thick 6061-T6 aluminum alloy is used for stamping and forming a ceiling of a truck cab, the concrete process flow of ceiling forming is determined by combining material characteristics and ceiling structure characteristics and is blanking → drawing → trimming → flanging and punching → shaping, and the like, and the blanking process has small stress strain, so the analysis is not carried out.
Based on the design theory of the covering part forming die, forming dies of all working procedures of the ceiling are established, the selection range of technological parameters of all working procedures is determined, and the optimal technological parameters and the blank shape and size of all working procedures are determined based on an optimization algorithm and a numerical simulation result. The method comprises the steps of carrying out multi-process forming simulation on a truck cab ceiling, considering a ceiling forming numerical simulation flow after demolding stress release to carry out drawing simulation on a plate material with a specific shape, ensuring that the surface of a part has no defects of cracking, severe wrinkling and the like by optimizing process parameters, carrying out rebound simulation on the basis of meeting the drawing forming result requirement, taking a formed part after the rebound simulation as the input of an edge cutting process, carrying out rebound simulation after edge cutting, wherein the formed part is the input of a flanging and punching process, and carrying out the rebound simulation after flanging and punching is the rebound quantity of the formed part finally.
And fitting a mathematical model of the change of the ceiling resilience along with the x coordinate and the y coordinate in each process by taking the x coordinate and the y coordinate of the ceiling as horizontal and vertical coordinates and the resilience s as a z coordinate. The formula (1) is a polynomial fitting formula, and each process parameter is shown in table 1, wherein R-square is a determination coefficient for representing the good and the bad of fitting, the range of the coefficient is [ 01 ], and the closer to 1, the better the fitting effect of the equation is. The resilience of the ceiling under any coordinate can be determined through the formula (1) and each parameter value, the R-square values of the three procedures are all above 0.87, and the fitting effect is good.
s(x,y)＝p00+p10x+p01y+p20x2+p11xy+p02y2+p30x3+p21x2y+p12xy2+p03y3+p40x4+p31x3y+p22x2y2+p13xy3+p04y4+p50x5+p41x4y+p32x3y2+p23x2y3+p14xy4+p05y5(1)
TABLE 1 parameters in polynomial fitting equation for each procedure
The resilience amount of any position of the ceiling can be calculated based on the precision transfer model, the mould profile compensation is carried out on the area of which the resilience amount is not in the specified range, and the flanging and punching process and the resilience simulation visible resilience of the compensated profile are controlled.
While the present invention has been described with reference to the embodiments shown in the drawings, the present invention is not limited to the embodiments, which are illustrative and not restrictive, and it will be apparent to those skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope of the invention as defined in the appended claims.
Claims (2)
1. A method for regulating and controlling the stamping forming precision of a lightweight car body covering part is characterized by comprising the following steps of:
s1, completing the multi-process forming modeling and the springback process simulation of the automobile body covering part;
s2, establishing an accuracy transfer model considering deformation and springback of each intermediate process: comparing the profile before springback of any procedure with the profile of the workpiece after springback of the procedure to obtain the springback amount of the procedure:
wherein the content of the first and second substances,sin order to obtain the amount of springback,xandyrespectively the horizontal and vertical coordinates of the covering part,p ij is composed ofThe value of the parameter(s) is,i、jis any value of 0 to 9; the influence of the n +1 th process on the springback value, i.e., the difference in springback value, can be seen by subtracting the springback value of the n +1 th process from the springback value of the n +1 th process
；
S3, calculating the resilience amount of each process at any position on the surface of the covering part based on the precision transfer model, and compensating the mould surface according to the calculated resilience amount so as to realize resilience control;
in step S2, if
>0, positive rebound is obtained, which indicates that the (n + 1) th procedure has a positive effect on the increase of the rebound quantity; if it is
If the value is not less than 0, the rebound is zero, which indicates that the n +1 st procedure has no influence on the increase of the rebound amount; if it is
If the value is less than 0, the rebound is negative, which indicates that the (n + 1) th procedure has a negative effect on the increase of the rebound amount.
2. The method for regulating the press forming accuracy of a lightweight vehicle body panel according to claim 1, wherein the step S1 further includes: 1. determining a covering part process flow by combining the structural characteristics and the material characteristics of the covering part; 2. establishing forming dies for all working procedures of the covering part through CAD (computer-aided design) and CAE (computer-aided engineering) software; 3. determining the optimal process parameters of each procedure; 4. and establishing a multi-process forming simulation model of the covering part based on CAE software, and adding springback simulation after each process to finish multi-process forming simulation of the covering part and analyze springback results.
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| CN109948279B (en) * | 2019-03-29 | 2022-12-20 | 江苏精研科技股份有限公司 | Simulation design method for shaping metal piece |
| CN110717272B (en) * | 2019-10-11 | 2023-06-09 | 内蒙古第一机械集团股份有限公司 | Coupling simulation method for material forming and modifying process |
| CN112033774A (en) * | 2020-08-24 | 2020-12-04 | 中国汽车工程研究院股份有限公司 | Anti concave test sample spare and fixing device of simulation automobile body outer covering piece |
| CN112828168B (en) * | 2020-12-31 | 2023-02-17 | 鹤壁天淇汽车模具有限公司 | Digital conversion manufacturing method for craftsman skill of magnesium-aluminum alloy automobile covering part die |
| CN115213302A (en) * | 2022-06-07 | 2022-10-21 | 中国第一汽车股份有限公司 | Mold surface over-A surface compensation method for optimizing surface quality of vehicle body outer covering part |
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| CN101549380B (en) * | 2008-04-03 | 2011-02-09 | 上海大众汽车有限公司 | Resilience control method for moulding top surface of car roof |
| CN101811156A (en) * | 2009-02-25 | 2010-08-25 | 江苏卡明模具有限公司 | Method for obtaining molding resilience value of plate based on CAE (Computer Aided Engineering) analysis method |
| CN102411641A (en) * | 2010-09-25 | 2012-04-11 | 集美大学 | Method for compensating rebounding error of automobile cover panel based on numerical simulation |
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