Research And Realization Of A New Method Of Dieless Forming Of Pipe

Plastic processing of Pipe is a processing technology that manufactures pipe accessories from pipe semi-finished products by the plastic processing method. Plastic processing of Pipe has been an important direction of advanced plastic processing technology researched and developed in the 21st century, because it's easy to meet the request of lighter, more durable and low consumption. And pipe plastic bending forming is an important portion of pipe plastic forming technology. Meanwhile , researches and applications of pipe bending equipment andprocessing technology of our country lag the world advanced level nowadays. In order to meet the step of Socialist modernization constructing, especially to meet the quick rising of the pipe bending accessory in industry just like automobile, shipping and so on., it's necessary to enhance manufacture level and automatization degree of our country's pipe bending processing. Moreover, the present pipe processing has new request to pipe bending technology. The previous three-dimensional CNC pipe bender can't bend a pipe in two directions that vertical at the same time, but this is required in the actual manufacture.In allusion to the characteristics of our country's CNC bend processing that can't bend a pipe in two directions vertical at the same time, and still need bending mold. This paper puts forward a new three-dimensional pipe bending method without mold, and actualized on the pipe bender designed ourselves. From the FEM analysis did on the pipe bending and springback process by the software ANSYS, we can conclude the relationship between the springback angle and the bending angle is linear, according to this, the compensatory values for springback reduction is provided. The experimental results shows that the new no-mold pipe bender designed in this paper, after the equalization, the precision of pipe accessories meet the requirements, and validate the practicability of the new no-mold bending technology. The paper consists of six chapters. In chapter 1, the introduction part firstly introduce the development situation of the pipe bending technology and the research actuality of pipe bending FEM simulation in and out of our nation. Meanwhile, in allusion to the characteristics of the present CNC bender still need bending mold and can't bend a pipe in two directions, confirmed the purpose and major task of this subject.Pipe bending distortion is belong to plastic distortion, which need to be solved with the theories of plastic.The third chapter first introduce stress thories of flexibility and plastic,and great flexibility distortion or plastic distortion. This chapter introduce Tresca Yield criteria, Mises Yield criteria, and Yield criteria of Strain-hardening material. This chapter mostly introduce the essential connection of flexibility and plastic and correlative formula, and provide foundation theories for finite elements analysis about pipe bending.The study and current development of tube material will use finite element simulate the bend molding process, and unifies with the computer assistance technological design constructs based on the theory, the experience and the value simulation steady computer assists the expert system is the tubing curving research development tendency. The fourth chapter uses the ANSYS software, has carried on the FEM simulation to the pipe bending non-heating and non-mold forming. First established finite element analysis model that conformed to the request, using the model simulated the pipe bending and springback process, and obtained the relations between the bending angle and the springback angle, drew the conclusion for regarding the thin tubing, the springback of the pipe angle increases along with the bending angle increases; As the basis, and established the springback equation:θ= k1θ′+ c1. In order to obtain a more accurate pipe, the compensatory values for springback reduction is provided in the control system,and the flow chart of programme is given.In chapter 4, the traditional bending process, pipe bending equipment and CNC bending technology is firstly introduced. In allusion to the disadvantages of the present CNC bending processing that still need bending mold, can only bend the given bending angle and can't bend a pipe in two directions, put forward a new no-heating bending forming processing without a mold, and designed new type CNC bending equipment. This chapter particularly introduced the overall structure and the principle of the pipe bender. Focus on the illuminating the formation of the bending radian, and analyses precise relationship between the elongation of the tank and the bending radian in the pipe bending process, induced the interrelated formula (in the formula, R stands for the bending radius; y stands for the elongation of the tank; x stands for the horizontal distance between the center of the active roller and the center of the fixed roller, this distance is decided by the mechanical structure of the bender, and it's fixed ). Through analyzing the structure of the pipe bender, we can get the conclusion that the minimum radius of pipe is the distance between the center of the active roller and the center of the fixed roller. Meanwhile, researched the software and hardware of the new type bender control system deeply, designed the control program of the bender based on the numerical control system of the bender, and it's compiled with VB6.0. Lastly in this chapter, researched the servo control system of the pipe bender, by adding PID linked control into the closed loop, reach the position control precision request of the servo control system, and ensure the academic bending angle of the pipe.Fifth chapter is about experiment, through pipe bending experiment on the bender, And comparing the actual curve and the goal curve, all the key points coordinate figure of two curve is extremely close and the value of deviation is acceptable. It indicate that the precision of the pipe after bending satisfies the request, and also confirmed the springback formula is correct which obtained through the finite element analysis.Finally in the last chapter, the summarization and foreground of the dissertation was given.