CN110110378B - A rapid detection method for mold-fitting of complex surfaces - Google Patents

Abstract

The invention discloses a method for rapidly detecting the mold sticking performance of a complex curved surface, which comprises the steps of firstly drawing a mold model in three-dimensional drawing software, and secondly introducing an entity model into finite element analysis software to perform punch forming simulation on a part to obtain an FLD (flash laser) image; and performing post-processing on the solved result file, and cutting the molded part at intervals of 45 degrees along the counterclockwise direction to obtain 4 important cutting surfaces. And finally, quantifying according to the distance between two points which are opposite to each other according to the one-to-one mapping relation between the point on the cutting line and the point on the convex die, and obtaining the die attaching data of the plate through finite element simulation software to simulate the die attaching state under the real condition. The forming effect of the workpiece is described more quickly and accurately, so that the level and the quality of the workpiece are improved.

Description

A rapid detection method for mold-fitting of complex surfaces

technical field

The invention relates to the field of stamping accuracy of thin plates, in particular to a method for quickly detecting mold-attachability of complex curved surfaces.

Background technique

Since the new century, with the improvement of national living standards, the production and manufacturing of automobiles has also occupied a very high proportion in the industry of the whole country. The vast majority of panels in automobiles are stamped from sheet metal. Therefore, there are high requirements for the precision and quality of stamping parts.

Because the traditional mold involves mostly relying on empirical formulas, the fault tolerance on the new type surface is low. With the development of computer-aided design technology, numerical simulation based on CAE technology is flourishing, and a large number of them are used in the design and test of molds, and the reliability has increased to 95%.

The ability of a blank to acquire the shape of a mold when a part with complex surfaces is stretched is called conformability. The traditional mold-fitting inspection relies on experienced mold engineers and is time-consuming and labor-intensive, and the obtained data often have large errors. Based on the finite element numerical simulation technology, the post-processing module can quickly observe the mold-fitting situation, and accurately and specifically measure the mold-fitting property. It provides a new idea and method for improving the process precision.

Contents of the invention

The purpose of the present invention is to solve the problem of long and inaccurate detection of mold-fitting properties of parts with complex curved surfaces, and propose a fast detection method for mold-fitting properties of complex curved surfaces.

The technical solution adopted by the present invention to solve the technical problem is: a method for fast detection of mold-holding properties of complex curved surfaces, which is realized by the following steps:

Step 1: Establish a three-dimensional solid model according to the geometric dimensions of the mold to be designed, and import the model into the finite element software for forming simulation to obtain the FLD image;

Step 2: Perform post-processing analysis on the simulated file, and then cut counterclockwise at the complex surface that is difficult to form, cut every 45°, and cut 4 times in total to obtain the cutting line;

Step 3: Mark multiple points equidistantly on the section line sheet and record their distances;

Step 4: Mark multiple points equidistantly on the profile punch and record their distances;

Step 5: Combining the idea of finite element discretization, map the target point on the section line to the punch to obtain the ideal point, use the distance between the target point and the ideal point to represent the mold-fitting property, and use the relational expression to quantify the surface-mounted mold Specifically, the closer the moldability is to 100%, the better the moldability is, and vice versa.

A method for rapidly detecting mold-fitting properties of complex curved surfaces according to claim 1, wherein the three-dimensional solid model in step 1 is in .iges format.

A method for rapidly detecting mold-fitting properties of complex curved surfaces according to claim 1, wherein the cut position in step 2 is a part of the complex curved surface that has high protrusions and is difficult to achieve mold-fitting.

A method for quickly detecting mold-fitting properties of complex curved surfaces according to claim 1, wherein the cutting angles in step 2 are 0°, 45°, 90°, and 135° counterclockwise.

A kind of fast detection method of mold sticking property of complex curved surface according to claim 1, it is characterized in that, in step 5, quantify by relational expression, its specific relational expression is:

Among them, η represents mold fitability, the actual distance between the target point and the ideal point is defined as A _i , the projection distance from the node on the punch to the starting position of the sheet is defined as B _i , and n is the number of nodes.

The beneficial effect of the present invention is that: a method for quickly detecting mold-fitting properties of complex curved surfaces in the present invention uses the post-processing module of finite element software to quickly and accurately obtain multiple section lines of any section of the part, and then according to the nodes on the section line The distance to the corresponding node on the punch, combined with the relationship between the moldability and each node, can get the specific value of the moldability. This method greatly improves the accuracy of the evaluation of the moldability, and proposes another reference way for the optimization of the process parameters.

Description of drawings

Figure 1 is the fender model in iges format;

Figure 2 is a 0° section;

Figure 3 is a 45° section;

Figure 4 is a 90° section;

Figure 5 is a 135° section.

detailed description

This embodiment is based on a fast detection method for mold-fitting properties of complex curved surfaces. The case model adopted is a car fender, and the specific detection steps are realized by the following steps:

Step 1: Establish a three-dimensional solid model according to the geometric dimensions of the mold to be designed, and import the model into the finite element software for forming simulation to obtain the FLD image;

Step 2: Perform post-processing analysis on the simulated file, and then cut counterclockwise at the complex surface that is difficult to form, cut every 45°, and cut 4 times in total to obtain the cutting line;

Step 3: Mark multiple points equidistantly on the section line sheet and record their distances;

Step 4: Mark multiple points equidistantly on the profile punch and record their distances;

Step 5: Combining the idea of finite element discretization, map the target point on the section line to the punch to get the ideal point, and use the distance between the target point and the ideal point to represent the fitability. The closer the fitability is to 100%, the better the fit is. The better the modulus, the worse it is.

The relationship between the conformability and the mapping nodes is:

Among them, η represents mold fitability, the actual distance between the target point and the ideal point is defined as A _i , the projection distance from the node on the punch to the starting position of the sheet is defined as B _i , and n is the number of nodes.

This time, this method is used to detect the fit between the fender punch and the sheet when there is no rebound after stamping. Import the fender model file in iges format as shown in Figure 1 into the numerical simulation software and select automatic settings, and submit it to the LS-dyna solver for solution after the settings are completed. After the solution is completed, open it in the post-processing module, observe its FLD image, and select the part that is difficult to form for sectioning. Cutting is performed counterclockwise, and the cutting angles are 0°, 45°, 90°, and 135°. Obtain the cutting lines shown in Figure 2, Figure 3, Figure 4, and Figure 5 respectively.

For places where the pasting is not sufficient, select points equidistant on the punch in the direction of the z-axis to correspond to points on the sheet. The distance between two points on the punch is defined as A _i , and the distance between the upper and lower corresponding points between the sheet and the punch is defined as B _i , the data of A _i and B _i are obtained through measurement, and the data are substituted into the formula to obtain The relationship between the moldability and each point is:

Among them, η represents moldability, the actual distance between the target point and the ideal point is defined as A _i , the projection distance from the node on the punch to the starting position of the sheet is defined as B _i , n is the number of nodes, and it is substituted into the formula It is calculated that the molding performance at the upper left corner of the fender is 78%, which indicates that the molding effect is not ideal.

Claims (5)

1. A method for rapidly detecting the sticking property of a complex curved surface is characterized by comprising the following steps:

the method comprises the following steps: establishing a three-dimensional solid model according to the geometric dimension of the mold to be designed, and importing the model into finite element software for molding simulation to obtain an FLD image;

step two: carrying out post-processing analysis on the simulated file, carrying out anticlockwise sectioning on the complex curved surface which is difficult to form, and sectioning at an interval of 45 degrees for 4 times to obtain a sectioning line;

step three: marking a plurality of points on the section line plate material at equal distances, and recording the distances;

step four: marking a plurality of points on the section line male die at equal distances, and recording the distances;

step five: and (3) mapping a target point on the section line on the convex die by combining a finite element discretization idea to obtain an ideal point, representing the die attaching performance by using the distance between the target point and the ideal point, and quantizing the concrete degree of the curved surface die attaching through a relational expression, wherein the closer the die attaching performance is to 100%, the better the die attaching performance is, and the worse the die attaching performance is.

2. The method for rapidly detecting the sticking property of the complex curved surface according to claim 1, wherein the three-dimensional solid model in the step one is in an iges format.

3. The method for rapidly detecting the sticking property of the complex curved surface according to claim 1, wherein the cutting position in the second step is a part of the complex curved surface, which has a high bulge and is difficult to stick.

4. The method for rapidly detecting the sticking property of the complex curved surface according to claim 1, wherein the cutting angle in the step two is counterclockwise 0 °, 45 °, 90 ° and 135 °.

5. The method for rapidly detecting the sticking property of the complex curved surface according to claim 1, wherein the quantization is performed through a relational expression in the fifth step, and the specific relational expression is as follows:

wherein eta represents the sticking model property, and the actual distance between the target point and the ideal point is defined as A _i And the projection distance from the node on the male die to the starting position of the plate is defined as B _i And n is the number of nodes.

Images