Comprehensive feeding thick material machine dynamics optimization design method

Abstract

The invention discloses a dynamic optimization design method for a comprehensive feeding thick material machine. The method comprises the following steps: step 1, establishing a kinematics analysis model; 2, establishing a kinetic analysis model; step 3, constructing a modal analysis model; and 4, establishing a dynamic balance optimization model. According to the method, the problems that a good optimization result is difficult to obtain by a common traditional optimization method and the calculation efficiency is low due to the fact that the geometrical relationship of an existing structural system is too complex are solved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of mechanism dynamics characteristic analysis and structure optimization, and relates to a comprehensive feeding thick material machine dynamics optimization design method. BACKGROUND

[0002] In the development of science and economy, the domestic sewing machine technology has achieved continuous innovation breakthrough. Like ordinary sewing machines, the thick material machine is also composed of various precision mechanisms, and the mechanisms work cooperatively in high-speed operation. However, the thick material machine may cause fluctuations in the sewing process due to thick sewing materials, and the internal movement mechanisms of the thick material machine may produce friction during high-speed operation, thereby causing wear of internal components and affecting the parts. With the increase of working speed, the complex and diverse internal structure of the thick material machine may cause vibration, noise and other adverse effects on the working performance; the vibration and noise of the thick material machine not only have irreversible effects on the service life of the machine, but also are not conducive to the working environment of the workshop and may affect the health of workers, so it is necessary to reduce the vibration of the thick material machine. The vibration caused by the unbalanced inertia load of the main transmission mechanism is the main source of the vibration of the thick material machine, and the optimization of the main transmission mechanism is relatively extensive, and the main purpose is to reduce the vibration caused by the unbalanced inertia load and reduce the vibration of the whole machine. The complete balancing method needs to be realized by counterweight, which makes the mechanism more complex than before, and the service life and reliability are relatively reduced; in the process of reducing the inertia force and the inertia moment, when one of them is reduced by partial balancing, the other one will be increased. For the comprehensive feeding thick material machine, due to the complex geometric relationship of the structure system, the general traditional optimization method is difficult to obtain good optimization results, and the calculation efficiency is low. SUMMARY

[0003] The application aims to provide a comprehensive feeding thick material machine dynamics optimization design method, which solves the problem that the general traditional optimization method is difficult to obtain good optimization results due to the complex geometric relationship of the existing structure system, and the calculation efficiency is low.

[0004] In order to achieve the above-mentioned purpose, the technical scheme adopted by the application is a comprehensive feeding thick material machine dynamics optimization design method, which is implemented according to the following steps: Step 1, establishing a kinematics analysis model; Step 2, establishing a dynamics analysis model; Step 3, constructing a modal analysis model; Step 4, establishing a dynamic balance optimization model.

[0005] The technical scheme of the application also has the following characteristics: In step 1, the kinematic analysis model is established, including: the structural analysis of the comprehensive feeding thick material machine, the establishment of the three-dimensional transmission model and the simulation model of the whole machine according to the size, position and size of each component of the physical prototype, and the analysis of the power transmission process of each component. It is known that the main transmission mechanism of the comprehensive feeding thick material machine can be divided into thread picking mechanism, fabric piercing mechanism and fabric feeding mechanism. These three mechanisms complete the whole sewing process.

[0006] In step 1, the kinematic analysis model also includes: analyzing each rod in the thread picking mechanism, fabric piercing mechanism and fabric feeding mechanism, drawing the motion diagram of each mechanism, and kinematically analyzing the mechanism. By establishing the kinematic equations of the three mechanisms and simulation calculation, the angular displacement, angular velocity and angular acceleration of the rod in each mechanism and the motion trajectory can be obtained by solving the above equations.

[0007] In step 2, the dynamic analysis model is established as follows: Firstly, dynamic static analysis is carried out on the main transmission mechanism of the comprehensive feeding thick material machine. Dynamic static analysis needs to introduce inertia load, and inertia load is related to the mass center acceleration of the component. Therefore, dynamic static analysis needs to analyze the motion of the mass center of the component and the force analysis of each component to establish the balance equation between each rod of the main transmission mechanism. Secondly, the balance equation is solved, that is, the constraint reaction force at each hinge and the inertia load of each mechanism are obtained. The motion pair reaction force generated by the mechanism is caused by the inertia effect during the movement of the mechanism, which reflects the mutual action between the parts at each hinge. The larger the motion pair reaction force, the more intense the collision between the two parts. By comparing the constraint reaction force at each hinge, it can be known that the constraint reaction force at the hinge of the thread picking and fabric piercing mechanism and the stitch mechanism is the largest. Then, the lumped mass method is used to simplify the comprehensive feeding thick material machine as a "mass-spring-damper" system, and the excitation source of the vibration system is the sum of the inertia loads of each mechanism. Because the size of each moving part inside the sewing machine is small and the weight is light, on the contrary, the size of the machine shell is large and the weight is large, so it can be approximately considered that the mass center of the sewing machine is unchanged during the movement of the mechanism. According to the comparison of the inertia load of each mechanism, a three-degree-of-freedom dynamic model of the whole machine is established. Finally, the three-degree-of-freedom dynamic equation of the whole machine is established by using the Lagrange method, and the natural frequency and mode shape parameters of the comprehensive feeding thick material machine are obtained by solving. The vibration acceleration curve of the whole machine can be solved by using the Runge-Kutta method, that is, the acceleration curve of the whole machine under different speeds can be obtained. It is known that the inertia load and the vibration acceleration are in direct proportion.

[0008] In step 3, the modal analysis model is constructed as follows: Firstly, the finite element modal analysis of the machine body of the comprehensive feeding thick material machine is carried out. The machine body is divided into three parts: the shell, the base and the shell-base. The material, constraint, load and boundary conditions of the imported analysis object are set according to the actual situation to meet the requirements of the actual working condition and ensure the accuracy of the modal analysis. The first six natural frequencies and vibration mode results of the shell, the base and the shell-base are calculated by using the post-processing module of the software. Secondly, during the sewing process of the sewing machine, the internal transmission mechanism moves. Some of the shaft parts are slender parts, and their natural frequencies are relatively low. Therefore, the upper shaft, the lower shaft and the shuttle shaft are determined as the analysis objects of the modal analysis because they are slender parts and rotate with the connected parts at high speed, while other parts only swing intermittently. Finally, the finite element modal analysis of the upper shaft, the lower shaft and the shuttle shaft is carried out by adding material, constraint, load and boundary conditions. Therefore, according to the calculation results of the finite element modal analysis, the six-order natural frequencies and vibration modes of the upper shaft, the lower shaft and the shuttle shaft are obtained.

[0009] Step 4: Establishing the dynamic balance optimization model, which is specifically: Firstly, based on the sensitivity analysis theory, the parameter space of the design variables needs to be sampled to obtain data during the sensitivity analysis. By sampling in the appropriate parameter space, the influence of the design variables on the output variables can be better understood. Due to the wide range of design variables, the optimal Latin hypercube design method is selected to design the sample set. Secondly, according to the characteristics of Sobol index method, which has high calculation efficiency and accuracy, and allows the design variables to change in different ranges simultaneously, the Sobol index method is used to calculate the sensitivity of each design variable to the system response. Since there are many design variables, only the first-order sensitivity value is calculated in this sensitivity analysis. By comparing the first-order sensitivity values of each design variable, the significant influencing factors can be obtained. Next, taking the root mean square of the total inertia force and inertia torque of the whole machine in a cycle as the optimization objective, the value range of the design variables is determined combined with the actual working conditions (such as material, installation position, etc.). According to the optimization variables selected by the sensitivity analysis, the optimization mathematical model is established. Finally, based on the established optimization mathematical model, the NSGA-II multi-objective genetic algorithm is used for optimization. The NSGA-II algorithm effectively solves the multi-objective optimization problem through these steps; this algorithm not only maintains the diversity of the population but also gradually approaches the Pareto optimal solution. The Pareto solution set is calculated using the NSGA-II optimization algorithm, and then the optimal solution is found based on the condition that the centroid position remains unchanged or changes only slightly.

[0010] Used for dynamic optimization of thick material feeders.

[0011] It is used in the transmission system of a comprehensive feeding machine for thick materials.

[0012] The beneficial effects of this invention are as follows: The dynamic optimization design method for the integrated feeding heavy-duty machine of this invention fully considers the new characteristics of the integrated feeding heavy-duty machine, the mutual influence between the complex internal mechanisms of the integrated feeding heavy-duty machine, and integrates the power transmission process between the mechanisms. Based on the dynamic static analysis results of the system, a dynamic balance optimization design model of the system is established. This method can obtain the significant influencing factors of the mass parameters and geometric parameters of each mechanism of the system, and can solve the optimization design problem of the integrated feeding heavy-duty machine with the total inertial force and total inertial torque of the whole machine as the target. At the same time, the model structure of this method is simple, which further improves the overall computational efficiency of the system. Attached Figure Description

[0013] Figure 1 This is the overall flowchart of the dynamic optimization design method for the integrated feeding thick material machine of the present invention. Detailed Implementation

[0014] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0015] Example 1 like Figure 1 As shown, the dynamic optimization design method for a comprehensive feeding thick material machine of the present invention is implemented according to the following steps: Step 1: Establish a kinematic analysis model; Step 2: Establish a dynamic analysis model; Step 3: Construct a modal analysis model; Step 4: Establish a dynamic balancing optimization model.

[0016] The present application is directed to the comprehensive feeding thick material machine dynamics optimization design problem, the kinematics theory is carried out to the whole machine mechanism to obtain the angular displacement, angular velocity and angular acceleration of each rod, through the dynamic static force theory analysis of the main transmission mechanism of the thick material machine, the maximum constraint reaction force of the pick thread and the needle spacing mechanism hinge can be obtained. By establishing the whole machine three degree of freedom dynamics equation, the inherent frequency characteristics of the whole machine can be obtained, and the relationship between the inertia load and the whole machine vibration acceleration can be obtained. Through the finite element modal analysis of the machine body and the main transmission parts, the inherent characteristics of each part can be obtained; The sensitivity analysis of the main vibration source mechanism is carried out, and the significant influence factor is obtained; the significant influence factor is used as the final design variable, the optimization mathematical model is established based on the dynamic balance theory, and the optimal solution of the star reducer can be obtained after the optimization solving of the NSGA-II multi-objective optimization algorithm.

[0017] Embodiment 2 As Figure 1 shown, unlike embodiment 1, in the step 1 of the comprehensive feeding thick material machine dynamics optimization design method of the present application in embodiment 2, The structure of the comprehensive feeding thick material machine is analyzed, the three-dimensional transmission model and the simulation model of the whole machine are established according to the size, position and size of each part of the entity prototype, and the dynamic transmission process of each part is analyzed. It can be known that the main transmission mechanism of the comprehensive feeding thick material machine can be divided into pick thread mechanism, needle mechanism and cloth feeding mechanism, which completes the whole sewing process of the cloth.

[0018] The rods in the pick thread mechanism, the needle mechanism and the cloth feeding mechanism are analyzed, the motion diagram of each mechanism is drawn, and the kinematics theory analysis of the mechanism is carried out. Through the establishment of the kinematics motion equation of the three mechanisms and the simulation calculation, the angular displacement, angular velocity and angular acceleration of the rods in the above equation can be obtained.

[0019] Embodiment 3 As Figure 1 shown, unlike embodiment 2, in the step 2 of the comprehensive feeding thick material machine dynamics optimization design method of the present application in embodiment 3, The dynamic analysis model of the component; first, the main transmission mechanism of the comprehensive feeding thick material machine is subjected to dynamic static force analysis. Dynamic static force analysis requires the introduction of inertial load, and the inertial load is related to the mass center acceleration of the component. Therefore, dynamic static force analysis needs to analyze the motion of the mass center of the component and the stress analysis of each component, and establish the balance equation between each link of the main transmission mechanism. Secondly, the above balance equation is solved, that is, the constraint reaction force at each hinge and the inertia load of each mechanism are obtained. The motion pair reaction force generated by the mechanism is caused by the inertia effect generated during the movement of the mechanism, which reflects the mutual action between parts at each hinge. The larger the motion pair reaction force, the more intense the collision between the two parts. By comparing and analyzing the constraint reaction force at each hinge, it can be known that the constraint reaction force at the hinge of the thread picking and cloth brushing mechanism and the pitch mechanism is the largest. Then, the whole comprehensive feeding thick material machine is simplified into a "mass-spring-damper" system by using the lumped mass method, and the excitation source of the vibration system is the sum of the inertia loads of each mechanism. Because the size of each moving part inside the sewing machine is small and the weight is light, on the contrary, the size of the machine shell is large and the weight is large, so it can be approximately considered that the mass center of the sewing machine is unchanged during the movement of the mechanism. According to the comparison of the inertia load of each mechanism, a three-degree-of-freedom dynamic model of the whole machine is established. Finally, the three-degree-of-freedom dynamic equation of the whole machine is established by using the Lagrange method, and the natural frequency and mode shape parameters of the comprehensive feeding thick material machine are obtained by solving. The vibration acceleration curve of the whole machine can be solved by using the Runge-Kutta method, that is, the acceleration curve of the whole machine under different rotating speeds can be obtained. It can be known that the inertia load and the vibration acceleration are in direct proportion.

[0020] Example 4 As Figure 1 shown, different from example 3, in the dynamic optimization design method of the comprehensive feeding thick material machine of the present application in example 4, in step 3: Component modal analysis model; firstly, the finite element modal analysis of the integrated feeding thick material machine body part is carried out, the body part is subdivided into the shell, the base and the shell-base three parts, the imported analysis object is set according to the actual situation, the material, the constraint, the load and the boundary condition are set, so as to meet the requirements of the actual working condition, so as to ensure the accuracy of the modal analysis. The post-processing module of the software can calculate the first six order natural frequencies and vibration mode results of the shell, the base and the shell-base three parts. Secondly, in the sewing process of the sewing machine, the internal transmission mechanism will move, among which the shaft parts belong to slender parts, and the natural frequency is relatively low compared with other parts. It can be known that since the upper shaft, the lower shaft and the rotating shuttle shaft belong to slender parts and will rotate with the fixed connected parts, and other parts only swing intermittently, so the analysis object of the modal analysis of the internal parts is determined. Finally, the finite element modal analysis of the upper shaft, the lower shaft and the rotating shuttle shaft is carried out by adding the material, the constraint, the load and the boundary condition. Therefore, according to the calculation results of the finite element modal analysis, the six order natural frequencies and vibration modes of the upper shaft, the lower shaft and the rotating shuttle shaft can be obtained.

[0021] Example 5 As Figure 1 shown, different from example 4, in the dynamic optimization design method of the integrated feeding thick material machine of the application in example 5, in step 4: The dynamic balance optimization model is constructed; firstly, based on the sensitivity analysis theory, the parameter space of the design variable is usually sampled to obtain data during the sensitivity analysis process, and the influence of the design variable on the output variable can be more comprehensively understood by sampling and taking values in the appropriate parameter space. Because the design variable level range is wide, the optimal Latin hypercube design method is selected to design the test of the design variable and extract the sample set; secondly, according to the characteristics that Sobol index method can calculate the efficiency and accuracy and allow the design variable to change in different ranges, the Sobol index method is used to calculate the sensitivity of each design variable to the system response. The sample set is analyzed by the Sobol index method, and because there are many design variables, only the first-order sensitivity value is calculated in this sensitivity analysis. By comparing the first-order sensitivity values between the design variables, the significant influencing factors can be obtained; then, taking the root mean square of the total inertia force and the inertia moment of the whole machine in a period as the optimization objective, combining the actual working conditions (such as materials, installation positions, etc.) to determine the value range of the design variable, and according to the optimization variables selected by the sensitivity analysis, the optimization mathematical model is established; finally, according to the established optimization mathematical model, the NSGA-II multi-objective genetic algorithm is used for optimization, and the NSGA-II algorithm effectively solves the multi-objective optimization problem through these steps. The algorithm not only can maintain the diversity of the population, but also can gradually approach the Pareto optimal solution. The Pareto solution set is calculated by the NSGA-II optimization algorithm, and then based on the condition that the centroid position is unchanged or changes little, the optimal solution is found.

[0022] Example 6 As Figure 1 shown, different from example 5, in the dynamic optimization design method of the comprehensive feeding thick material machine of the application in example 6, it is applied to the transmission system of the comprehensive feeding thick material machine.

[0023] The above description shows and describes several preferred embodiments of the application, but as previously described, it should be understood that the application is not limited to the forms disclosed herein, should not be considered as excluding other embodiments, and can be used in various other combinations, modifications and environments, and can be modified within the scope of the inventive concept described herein by the above teaching or related art or knowledge. The modifications and changes made by those skilled in the art without departing from the spirit and scope of the application shall be within the protection scope of the claims of the application.

Claims

1. A method for optimizing the dynamics of a comprehensive feeding thick material machine, which is implemented according to the following steps: Step 1: establishing a kinematics analysis model; Step 2: establishing a dynamics analysis model; Step 3: constructing a modal analysis model; Step 4: establishing a dynamic balance optimization model.

2. The method of claim 1, wherein, In the step 1, the kinematics analysis model is established, which includes: performing structural analysis on the comprehensive feeding thick material machine, establishing a three-dimensional transmission model and a simulation model of the whole machine according to the size, position and size of each component of the physical prototype, and analyzing the power transmission process of each component. It is known that the main transmission mechanism of the comprehensive feeding thick material machine can be divided into thread picking mechanism, fabric piercing mechanism and fabric feeding mechanism, and the three mechanisms complete the whole sewing process.

3. The method of claim 2, wherein In the step 1, the kinematics analysis model also includes: analyzing each rod in the thread picking mechanism, fabric piercing mechanism and fabric feeding mechanism, drawing a motion diagram of each mechanism, and performing kinematics theory analysis on the mechanism. By establishing the kinematics motion equation of the three mechanisms and performing simulation calculation, the angular displacement, angular velocity and angular acceleration of the rod in each mechanism and the motion trajectory can be obtained by solving the above equation.

4. The method of claim 3, wherein, In the step 2, the dynamics analysis model is established as follows: Firstly, dynamic static force analysis is performed on the main transmission mechanism of the comprehensive feeding thick material machine. Dynamic static force analysis requires the introduction of inertial load, and the inertial load is related to the mass center acceleration of the component. Therefore, dynamic static force analysis requires motion analysis of the mass center of the component and force analysis of each component, and the balance equation between each rod of the main transmission mechanism is established. Secondly, the balance equation is solved, and the constraint reaction force at each hinge and the inertia load of each mechanism are obtained. The motion pair reaction force generated by the mechanism is caused by the inertia effect during the motion process of the mechanism, which reflects the mutual action between the parts at each hinge. The larger the motion pair reaction force, the more intense the collision between the two parts. By comparing the constraint reaction forces at each hinge, it can be known that the constraint reaction forces at the hinges of the thread picking and fabric piercing mechanisms and the stitch mechanism are the largest. Then, the comprehensive feeding thick material machine is simplified as a "mass-spring-damper" system by using the lumped mass method. The excitation source of the vibration system is the sum of the inertia loads of each mechanism. Since the size and weight of each moving part inside the sewing machine are small, the mass center of the sewing machine is approximately constant during the motion process of the mechanism. According to the comparison of the inertia loads of each mechanism, a three-degree-of-freedom dynamics model of the whole machine is established. Finally, the three-degree-of-freedom dynamics equation of the whole machine is established by using the Lagrange method, and the natural frequency and mode shape parameters of the whole machine are obtained by solving. The vibration acceleration curve of the whole machine can be obtained by using the Runge-Kutta method, and the acceleration curve of the whole machine under different speeds can be obtained. It is known that the inertia load and the vibration acceleration are in direct proportion.

5. The method of claim 4, wherein, In the step 3: the modal analysis model is constructed as follows: Firstly, the finite element modal analysis of the machine body of the comprehensive feeding thickener is carried out, the machine body is divided into three parts of the shell, the base and the shell-base, the material, the constraint, the load and the boundary condition of the imported analysis object are set according to the actual situation, so as to meet the requirements of the actual working condition and ensure the accuracy of the modal analysis; The post-processing module of the software can calculate the first six natural frequencies and mode shapes of the shell, the base and the shell-base; Secondly, during the sewing process of the sewing machine, the internal transmission mechanism moves, some of the shaft parts are slender parts, and the natural frequency of the shaft parts is relatively low, so it is determined that the internal parts are the analysis objects of the modal analysis because the upper shaft, the lower shaft and the shuttle shaft are slender parts and rotate with the fixed connected parts, and other parts only swing intermittently; Finally, the finite element modal analysis of the upper shaft, the lower shaft and the shuttle shaft is carried out by adding material, constraint, load and boundary condition; therefore, according to the calculation results of the finite element modal analysis, the six natural frequencies and mode shapes of the upper shaft, the lower shaft and the shuttle shaft are obtained.

6. The method of claim 5, wherein, The step 4 of establishing the dynamic balance optimization model is specifically: Firstly, based on the sensitivity analysis theory, the parameter space of the design variable is usually sampled to obtain data during the sensitivity analysis, and the influence of the design variable on the output variable can be more comprehensively understood by sampling in the appropriate parameter space; because the level range of the design variable is wide, the optimal Latin hypercube design method is selected to design the sample set of the design variable; Secondly, according to the characteristics of the Sobol index method that the calculation efficiency and accuracy are high and the design variables can change in different ranges at the same time, the Sobol index method is used to calculate the sensitivity of each design variable to the system response; the sample set is analyzed by the Sobol index method, and because there are many design variables, only the first-order sensitivity value is calculated in this sensitivity analysis; the significant influencing factors can be obtained by comparing the first-order sensitivity values of each design variable; Then, taking the root mean square of the total inertia force and the inertia moment of the whole machine in a cycle as the optimization target, combining the actual working condition (such as material, installation position, etc.) to determine the value range of the design variable, and according to the optimization variables selected by the sensitivity analysis, an optimization mathematical model is established; Finally, according to the established optimization mathematical model, the NSGA-II multi-objective genetic algorithm is used for optimization, and the NSGA-II algorithm effectively solves the multi-objective optimization problem through these steps; The algorithm not only maintains the diversity of the population, but also gradually approaches the Pareto optimal solution; the Pareto solution set is calculated by the NSGA-II optimization algorithm, and then the optimal solution is found based on the condition that the centroid position is unchanged or changes little.

7. The method of claim 6, wherein, It is used for the dynamic optimization of the feeding thickener.

8. The method of claim 7, wherein, It is applied to the transmission system of the comprehensive feeding thickener.

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