On Key Technology Of In-Line Punching Unit For Ventral Punching Of U-Shaped Longitudinal Beam

The punching process and equipment for the web of U-shaped longitudinal beams based on in-line punching units is a new technology with the advantages of fast punching frequency and high processing efficiency.Currently,it is still in the blank in China.As the core component of this new type of process equipment,the in-line punching unit undertakes the important tasks of mold selection,punching,and hole searching.Based on the punching process requirements and technical parameters of the punching unit,this paper conducts research on relevant key technologies in the aspects of structural design,motion control,and punching strategy of the punching unit,with the aim of achieving the rapidity,accuracy,and stability of the punching unit while completing the longitudinal beam punching function,In order to lay the foundation for the localization of high-end longitudinal beam web punching CNC equipment,the main research contents and conclusions of this article are as follows:(1)Analysis of the punching process for the web of the U-shaped longitudinal beam and determination of the technical parameters of the punching unit.By analyzing typical U-shaped longitudinal beam drawings,information such as the type,quantity,and proportion of longitudinal beam web holes was obtained,and the equipment layout and punching process flow of the U-shaped longitudinal beam web punching production line based on a multi-station press were established.Through numerical simulation of the punching process,reasonable blank holder force parameters were determined,the impact of the blank holder force on the punching quality was analyzed,and the punching force-stroke curve and the cross-sectional shape of the hole were obtained.Considering the eccentric load of the press and the functional requirements of the punching unit,the layout of the punching unit was carried out,and the layout of the punching unit on the press table was obtained.Finally,the main technical parameters of the punching unit are determined through analysis and calculation,providing a basis for the structural design of the punching unit.(2)Structural design of in-line punching unit.Based on the requirements of the punching process and technical parameters of the punching unit,the overall structure design of the single and dual mold punching units composed of the punching module,the mold selection module,the Y-axis motion system,and the mold base was carried out.A punch assembly is designed that uses convex and concave die devices to complete the punching function,and devices such as a press plate,nitrogen spring,and return spring to complete the blank pressing,unloading,and reset functions.A mold selection assembly is designed that uses pneumatic cylinders,gear racks,and other devices to achieve the mold selection function.A Y-axis motion system that relies on servo motors and ball screw systems to complete the mold frame body hole searching is designed,and support The guided function of the mold base and the Z-direction guide rail.The completion of the structural design of the in-line punching unit lays the foundation for the subsequent motion analysis and punching strategy formulation of the punching unit.(3)Research on motion control of Y-axis motion system of in-line punching unit.In order to obtain a good hole searching motion curve,the mathematical models of the mechanical and electrical control parts are established for the Y-axis motion system of the punching unit,and the motion control simulation analysis is performed using MATLAB software.Through simulation,the advantages and disadvantages of three different acceleration and deceleration algorithms,namely,traditional trapezoidal,5th degree S-type,and new 5th degree polynomial,in both long stroke and short stroke modes are analyzed.Through analysis and comparison,a new 5-degree polynomial acceleration and deceleration algorithm is ultimately selected,which takes less time and has the best smoothness.It can improve the smoothness and positioning accuracy of the Y-axis motion of the punching unit,and is therefore more suitable for motion control of the Y-axis motion system of the punching unit.(4)Research on punching strategy of in-line punching unit.By analyzing the factors affecting the punching efficiency of the web of the U-shaped longitudinal beam of a multistation press,it is concluded that shortening the path cannot effectively improve the efficiency.When the press equipment is determined,reducing the number of punching times can effectively improve the punching efficiency.By establishing a mathematical model of punching strategy,a punching library and a mold library were obtained,and punching strategies based on single punching mode and multiple punching mode were developed.Case studies were conducted,and corresponding punching strategy flow charts and punching strategy information tables were obtained.Finally,the punching efficiency of different punching modes is compared,and the results show that the punching efficiency based on multi punching strategy is the highest.The research on punching strategy lays a foundation for the development of automatic punching strategy generation software.(5)Inline punching unit punching strategy generation software.Based on the research results of punching strategy,using the Visual Studio software development tool,an automatic generation software of punching strategy has been developed.The software can achieve functions such as information extraction of the web hole of the car longitudinal beam,establishment of a mold library,mold adaptation,and automatic generation of punching strategy.It has initially achieved commercial application.