A method for predicting and compensating springback in free bending forming based on axial advancing speed

Abstract

The application provides a free bending forming springback amount prediction and compensation method based on axial advancing speed, characterized in that on the basis of studying the influence of axial advancing speed on the forming precision of pipe materials, a linear equation between the bending angle and the springback angle is first obtained, and then the corresponding relationship between the parameters and the axial advancing speed is established according to the corresponding parameters of the relational equation; the application realizes the bending angle error prediction and compensation function caused by the change of the axial advancing speed, can obtain a pipe material component with an error of no more than 2.5% between the experimental piece and the simulation piece, improves the forming precision of the pipe material, and realizes the precision error compensation caused by the selection of the axial advancing speed.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of metal component forming manufacturing, in particular to a free bending forming springback amount prediction and compensation method based on axial advancing speed. BACKGROUND

[0002] Pipe components are widely used in aerospace, chemical industry, oil transportation, shipbuilding and medical devices due to their aesthetic appearance, light weight and high strength. The free bending technology was first proposed by Japanese scientist Murata et al. The free bending technology has the advantages of simple structure and no need to change the bending die for manufacturing pipe components with different bending radii. This advantage overcomes the shortcomings of numerical control bending technology in pipe bending forming, and solves the problem of high degree of freedom and customized small batch pipe components in the market. According to the forming principle analysis of free bending technology, the pipe is continuously fed at the axial advancing speed V during the forming process. The axial advancing speed V as the only active determined forming parameter has a great influence on the pipe forming precision and quality, so it is necessary to establish a springback angle prediction model considering the inconsistent pipe springback angle caused by the change of axial advancing speed.

[0003] Pipe bending springback is an important factor affecting pipe precision, which is influenced by many factors such as material parameters and forming parameters. Among them, the material parameters have a greater influence on springback, but the influence of forming parameters cannot be ignored. The axial advancing speed as the only active determined forming parameter in the free bending forming process has a great influence on the pipe forming precision. In order to solve the inconsistent springback angle under different axial advancing speeds, the pipe springback value corresponding to different axial advancing speeds needs to be predicted and compensated to obtain pipe forming parts with high forming precision. SUMMARY

[0004] The purpose of the present application is to provide a free bending forming springback amount prediction and compensation method based on axial advancing speed to solve the problem of different pipe springback values caused by different axial advancing speeds.

[0005] To achieve the above purpose, the present application provides the following technical solutions:

[0006] A free bending forming springback amount prediction and compensation method based on axial advancing speed, characterized in that, in view of the problem that different axial advancing speeds will cause different springback angles, a springback angle prediction method corresponding to different axial advancing speeds is established, and the specific method is:

[0007] Firstly, the springback value θ of different bending angles under different axial advancing speeds V is obtained through experiment S ; based on the determined springback value, the bending angle θ and the springback angle θ SThe relational equation (θ) S =k Vn θ+b Vn Based on the parameter k in the relational equation. Vn and b Vn Establish axial propulsion speeds V and k respectively Vn and b Vn Relationship equation Based on the axial propulsion speed and bending angle determined by actual production, a springback prediction model is used. Determine the rebound angle θ S Subsequently, a bending angle compensation coefficient k is introduced to correct the calculation formula for the forming parameters of the circular arc segment. Finally, based on the determined bending angle θ and axial advance speed V, the forming parameters are obtained through the circular arc segment forming parameter calculation model, and pipe processing experiments are conducted.

[0008] The method for predicting and compensating springback in free bending forming based on axial propulsion speed includes the following steps:

[0009] Step 1: Set up and conduct pipe processing experiments with different bending angles at different axial advance speeds, and extract the springback angle θ corresponding to each pipe processing experiment based on the experimental results. S ;

[0010] Step 2: Based on the rebound angle θ S Based on the following fitted equations, the least squares method was used to obtain the bending angle θ and the springback angle θ at different axial propulsion speeds. S The fitting equation between them:

[0011] θ S =k Vn θ+b Vn

[0012] Where k Vn and b Vn The correlation coefficient represents the fitted relationship.

[0013] Step 3: Fit the correlation coefficient k within the obtained relationship for different axial thrust velocities. Vn Use the following equation for k Vn Establish a fitting relationship with the axial propulsion speed V:

[0014] k Vn =k k V+b k

[0015] Where, k k and b k The correlation coefficient is used for fitting.

[0016] Step 4: Fit the correlation coefficient b within the obtained relationship for different axial thrust velocities.Vn , the b Vn and axial propulsion speed V are established by using the following equation:

[0017]

[0018] Wherein, a b , b b and c b are the fitting correlation coefficients

[0019] Step 5: Obtain the corresponding bending springback angle θ S Prediction model under different axial propulsion speed as follows:

[0020]

[0021] Step 6: According to step 6 springback angle prediction model, introduce bending angle compensation coefficient k and correct the forming parameter calculation model based on free bending technology as follows:

[0022]

[0023] Wherein, U is the eccentricity, U Max is the maximum eccentricity, t S2 is the arc segment S2 running time, R is the bending radius, and A is a constant.

[0024] Step 7: Determine the bending angle θ, axial propulsion speed V, use the forming parameter calculation model shown in step 6 to obtain the forming parameter and carry out pipe processing experiment.

[0025] Compared with the prior art, the present application has the following advantages:

[0026] The method provided by the present application avoids the problem of different bending springback angles caused by different axial propulsion speeds, realizes the prediction function of pipe bending springback value, and can obtain the springback value before bending processing experiment. The bending angle error of the pipe component after optimization of the present application is not more than 2.5%, realizing high-precision forming of the pipe, and having high popularization and application value. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 is the process flowchart of the method of the present application;

[0028] Figure 2 is the data result graph obtained by experiment of the corresponding springback value of different bending angles under different bending speeds of the present application;

[0029] Figure 3 is the design piece of the example pipe component;

[0030] Figure 4A pipe experimental piece not optimized for example

[0031] Figure 5 A pipe experimental piece optimized by the method of the present application for example. DETAILED DESCRIPTION

[0032] To illustrate the technical problems, technical solutions, implementation processes and performance displays, the present application will be further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described here are only used to explain the present application, and are not intended to limit the present application. Various exemplary embodiments, features and aspects of the present disclosure will be described in detail below with reference to the accompanying drawings. The same reference signs in the drawings represent functionally identical or similar elements. Although various aspects of the embodiments are shown in the drawings, the drawings are not necessarily drawn to scale unless specifically indicated.

[0033] The word "exemplary" used herein means "serving as an example, an embodiment, or an illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments.

[0034] In addition, in order to better illustrate the present disclosure, a large number of specific details are given in the specific embodiments below. Those skilled in the art should understand that the present disclosure can also be implemented without certain specific details. In some examples, methods, means, elements and circuits well known to those skilled in the art are not described in detail, in order to highlight the main idea of the present disclosure.

[0035] Embodiment 1

[0036] As shown in Figure 1 , a free bending forming springback amount prediction and compensation method based on axial advancement speed, characterized in that the method comprises the following steps:

[0037] Step 1: Set up and conduct pipe processing experiments at different bending angles under different axial advancement speeds, and extract the corresponding springback angle θ S from each pipe processing experiment according to the experimental results, the specific experimental data are shown in Figure 2 ;

[0038] Step 2: Based on the springback angle θ S , a fitting equation between the bending angle θ and the springback angle θ S under different axial advancement speeds is established as follows, the fitting equation between the bending angle and the springback angle is obtained using the least squares method based on the following fitting equation, and the correlation coefficients of the bending angle and the springback angle under each axial advancement speed value are shown in Table 1:

[0039] θ S = k Vn θ+b Vn

[0040] Where k Vn and b Vn The correlation coefficient represents the fitted relationship.

[0041] Table 1 Correlation coefficients for propulsion speeds at each axial direction.

[0042]

[0043] The subsequent calculations are performed based on the correlation coefficients corresponding to each axial thrust speed value in Table 1;

[0044] Step 3: Fit the correlation coefficient k within the obtained relationship for different axial thrust velocities. Vn Use the following equation for k Vn Establish a fitting relationship with the axial propulsion speed V:

[0045] k Vn =0.00064V + 0.068

[0046] Step 4: Fit the correlation coefficient b within the obtained relationship for different axial thrust velocities. Vn Apply the following equation to b Vn Establish a fitting relationship with the axial propulsion speed V:

[0047] b Vn =-2.771e -0.16V +1.571

[0048] Step 5: Obtain the bending springback angle θ corresponding to different axial propulsion speeds. S The prediction model is shown below:

[0049] θ S =θ(0.00064V+0.068)-2.771e -0.16V +1.571

[0050] Step 6: Based on the springback angle prediction model in Step 6, introduce the bending angle compensation coefficient k and correct the forming parameter calculation model based on free bending technology as shown below:

[0051]

[0052] Step 7: Based on the design target requirements, determine the bending angle as 110° and the axial advance speed as 18 mm / s. Determine U = U based on the experimental U / R relationship. Max =2.5mm, A is a constant, A = 12.5mm. The forming parameters of the arc segment S2 are obtained using the forming parameter calculation model shown in step 6, and a tube processing experiment is conducted.

[0053] U = 2.5mm

[0054] t S2 =8.87s

[0055] like Figures 3-5 The experimental comparison results shown show that the error between the unoptimized experimental part and the design part is 9.23%. The springback angle corresponding to the axial propulsion speed obtained by the present invention is 10.16°. The error between the experimental part and the design part after optimization by the present invention is 2.01%. Compared with the unoptimized pipe component, the forming accuracy of the experimental pipe is 7.22%, which solves the problem of different springback angles under different axial propulsion speeds and improves the forming accuracy of pipe processing based on free bending technology.

[0056] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for predicting and compensating springback amount in free bending forming based on axial advancing speed, characterized in that, In view of the problem that different axial advancing speeds cause different rebound angles, a rebound angle prediction method corresponding to different axial advancing speeds is established, and the specific method is as follows: First, the springback values ​​at different bending angles under different axial propulsion speeds V were obtained through experiments. Based on the determined springback value, establish the bending angle at different speeds. With rebound angle Relationship equations ( Based on the parameters in the relational equation and Establish axial propulsion speed V and and Relationship equations ( and Based on the axial propulsion speed and bending angle determined by actual production, a springback prediction model is used. Determine the rebound angle ; Then, the bending angle compensation coefficient k is introduced to modify the calculation formula of the forming parameters of the circular arc segment. Finally, based on the determined bending angle and the axial advancing speed V, the forming parameters are obtained through the calculation model of the forming parameters of the circular arc segment, and the pipe processing experiment is conducted. Specifically includes the following steps: Step 1: set up and conduct pipe material processing experiments with different bending angles at different axial pushing speeds, and extract the corresponding springback angles of each pipe material processing experiment according to the experimental results ; Step 2: Based on the rebound angle The fitting equation between the bending angle and the rebound angle at different axial propulsion speeds was obtained using the least square method based on the following fitting equation: ； wherein and is the correlation coefficient for the fitted relationship; Step 3: Correlation coefficient within the fitted relationship of the obtained different axial propulsion speeds , a fitted relationship is established between the axial propulsion speed V and the axial propulsion speed V using the following equation: and the axial propulsion speed V ； wherein and is the correlation coefficient of the fit; Step 4: Correlation coefficient within the fitted relationship of the obtained different axial propulsion speeds , a fitted relationship is established between the axial propulsion speed V and the axial propulsion speed V using the following equation: and the axial propulsion speed V ； wherein , and is the correlation coefficient of the fit Step 5: Obtain the corresponding bending springback angle under different axial pushing speeds The prediction model is shown as follows: ； Step 6: According to the rebound angle prediction model in step 5, introduce the bending angle compensation coefficient k and modify the forming parameter calculation model based on the free bending technology as follows: ； wherein, , U is eccentricity, is the arc segment S2 running time, R is the bending radius, A is a constant; Step 7: Determine bending angle The forming parameters of the circular arc segment S2 are obtained using the forming parameter calculation model shown in step 6, and a pipe material processing experiment is performed.

Images