Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a springback compensation method for bending and forming a wire rod, which solves the problem of low accuracy of bending and forming the wire rod caused by a springback phenomenon.
The technical scheme of the invention is as follows: the wire bending forming springback compensation method comprises the following steps:
s01, establishing a wire bending forming analysis model: the curvature radius of the wire bending forming is related to the feeding amount of a cutter, and the formula 1 is shown;
wherein h is the theoretical feeding amount of the cutter; b is the vertical distance from the upper end of the cutter cavity to the bottom end of the cutter; rho is a target curvature radius; alpha is an included angle formed by the extending direction of the cutter cavity and a vertical plane; l is the vertical distance from the upper end of the cutter cavity to the end face of the mandrel;
s02, establishing a forming curvature radius iterative compensation model:
the method comprises the steps of establishing a forming curvature radius iterative compensation model based on the theoretical feed quantity of a cutter by taking the forming curvature radius as an iteration quantity as the target of bending and forming the wire rod, performing compensation calculation according to the iterative compensation method to gradually reduce the forming curvature radius and approach the target curvature radius, completing iterative compensation calculation when the difference value between the forming curvature radius and the target curvature radius is within the error allowable range of the target curvature radius, and applying the theoretical feed quantity of the cutter obtained by the last iterative compensation calculation to actual processing.
The further technical scheme of the invention is as follows: the step S02 is specifically as follows:
a. obtaining a functional relation between the theoretical feed amount h of the cutter and the target curvature radius rho through a formula 1, referring to a formula 2;
equation 2: h ═ f (ρ);
wherein h is the theoretical feeding amount of the cutter; rho is a target curvature radius;
b. setting a target curvature radius rho, substituting the target curvature radius rho into a formula 2 to calculate the theoretical feed amount h of the cutter, and performing a Deform simulation experiment based on the calculated h value to obtain a forming curvature radius rho s Setting a forming radius of curvature ρ s The functional relationship between the theoretical feed amount h of the cutter is shown in formula 3;
equation 3: rho s =g(h);
Where ρ is s To form a radius of curvature; h is the theoretical feeding amount of the cutter;
c. from equations 2 and 3, the forming radius of curvature ρ can be derived s The functional relationship with the target radius of curvature ρ, see equation 4;
equation 4: rho s =g(h)=g[f(ρ)];
Where ρ is s To form a radius of curvature; rho is a target curvature radius; h is the theoretical feeding amount of the cutter;
d. since the final objective of the iterative compensation model is to gradually reduce the forming curvature radius and approach the target curvature radius, the target curvature radius rho is assigned to the forming curvature radius rho s And constructing a wire bending forming error function; see equation 5;
wherein, the first and the second end of the pipe are connected with each other,
is a wire bending forming error; rho is a target curvature radius; rho
s To form a radius of curvature;
e. an iterative compensation formula can be deduced according to formulas 2, 3, 4 and 5, see formula 6;
where ρ is
i+1 Is the target radius of curvature for the next stage of iteration,
for the iteration wire bending forming error of the grade, rho
i Is the forming radius of curvature of the current stage iteration.
Compared with the prior art, the invention has the following advantages:
the method comprises the steps of calculating the cutter feeding amount for multiple times in a mode of establishing an iterative compensation model so as to overcome the bending forming error caused by the rebound phenomenon, wherein a product processed on the basis of the cutter feeding amount calculated each time has higher precision than a product processed on the basis of the cutter feeding amount calculated last time, and the product processed on the basis of the cutter feeding amount calculated last time can enable the forming curvature radius of the product to approach the target curvature radius and fall within the error range allowed by the target curvature radius.
The invention is further described below with reference to the figures and examples.
Detailed Description
Example 1:
as shown in fig. 1, the wire bending forming springback compensation method comprises the following steps:
s01, establishing a wire bending forming analysis model: the curvature radius of the wire bending forming is related to the feeding amount of a cutter, and the formula 1 is shown;
wherein h is the theoretical feeding amount of the cutter; b is the vertical distance from the upper end of the cutter cavity to the bottom end of the cutter; ρ is the target radius of curvature (the median value between the outside diameter of the wire and the inside diameter of the wire); alpha is an included angle formed by the extending direction of the cutter cavity and a vertical plane; l is the vertical distance from the upper end of the cutter cavity to the end face of the mandrel.
S02, establishing a forming curvature radius iterative compensation model:
the method comprises the steps of establishing a forming curvature radius iterative compensation model based on the theoretical feed quantity of a cutter by taking the forming curvature radius as an iteration quantity as the target of bending and forming the wire rod, performing compensation calculation according to the iterative compensation method to gradually reduce the forming curvature radius and approach the target curvature radius, completing iterative compensation calculation when the difference value between the forming curvature radius and the target curvature radius is within the error allowable range of the target curvature radius, and applying the theoretical feed quantity of the cutter obtained by the last iterative compensation calculation to actual processing.
The step S02 is specifically as follows:
a. obtaining a functional relation between the theoretical feeding amount h of the cutter and the target curvature radius rho through a formula 1, referring to a formula 2;
equation 2: h ═ f (ρ);
wherein h is the theoretical feeding amount of the cutter; rho is a target curvature radius;
b. setting a target curvature radius rho, substituting the target curvature radius rho into a formula 2 to calculate the theoretical feed amount h of the cutter, and performing a Deform simulation experiment based on the calculated h value to obtain a forming curvature radius rho s Setting a forming radius of curvature ρ s The functional relationship between the theoretical feed amount h of the cutter is shown in formula 3;
equation 3: rho s =g(h);
Wherein ρ s To form a radius of curvature; h is the theoretical feeding amount of the cutter;
c. from equations 2 and 3, the forming radius of curvature ρ can be derived s The functional relationship with the target radius of curvature ρ, see equation 4;
equation 4: rho s =g(h)=g[f(ρ)];
Where ρ is s To form a radius of curvature; rho is a target curvature radius; h is the theoretical feeding amount of the cutter;
d. since the final objective of the iterative compensation model is to gradually reduce the forming curvature radius and approach the target curvature radius, the target curvature radius rho is assigned to the forming curvature radiusRadius of curvature ρ s And constructing a wire bending forming error function; see equation 5;
wherein the content of the first and second substances,
forming error for wire bending; rho is a target curvature radius; rho
s To form a radius of curvature;
e. an iterative compensation formula can be derived according to the formulas 2, 3, 4 and 5, see formula 6;
where ρ is
i+1 Is the target radius of curvature for the next stage of iteration,
for the iteration wire bending forming error of this stage, rho
i Is the forming radius of curvature of the current stage iteration.
The verification process of the method is as follows:
1. primary calculation: the target curvature radius ρ is set to 40mm, and the error accuracy λ is ± 0.3 mm. Firstly, substituting the relevant parameters into the formula 1, and calculating the theoretical feed h of the cutter to be 14 mm. Then, performing a Deform simulation experiment based on the theoretical feed amount h of the cutter to obtain a forming curvature radius of 43.639mm and a forming error of-3.639 mm. And the error is greater than the required error precision, and the error is unqualified, so the first compensation calculation is carried out.
2. Compensation for the first time: and substituting the parameters of the initial calculation into a formula 6, calculating to obtain the target curvature radius of 36.361mm of the iteration, substituting the related parameters into a formula 1, and calculating the theoretical feed h of the cutter to be 17.5 mm. Then, a Deform simulation experiment is carried out based on the theoretical feed amount h of the cutter, the forming curvature radius is calculated to be 41.367, and the forming error is-1.367 mm. And the error is greater than the required error precision, and the error is unqualified, so the second compensation calculation is carried out.
3. And (3) second compensation: substituting the parameters of the first compensation into a formula 6, calculating to obtain the target curvature radius of 34.994mm of the iteration, substituting the related parameters into a formula 1, and calculating to obtain the theoretical feed h of the cutter to be 18.8 mm. Then, a Deform simulation experiment is carried out based on the theoretical feeding amount h of the cutter, and the forming curvature radius is calculated to be 40.418mm, and the forming error is-0.418 mm. And if the error is greater than the required error precision, the error is unqualified, so that the third compensation calculation is performed.
4. And (3) compensation for the third time: substituting the parameters of the second compensation into a formula 6, calculating to obtain the target curvature radius of 34.576mm of the iteration, substituting the related parameters into a formula 1, and calculating the theoretical feed h of the cutter to be 19.2 mm. Then, a Deform simulation experiment was performed based on the theoretical feed amount h of the tool, and the molding radius of curvature was calculated to be 39.859mm, and the molding error was calculated to be 0.141 mm. The error meets the requirements.
The iterative compensation results are shown in table 1: