Parameter design of the experimental platform of the plane fiber laser cutting machine

by:Lxshow     2021-05-23

The structure parameters of the experimental platform of the plane fiber laser cutting machine. This paper designs an experimental platform for the plane mechanism cutting machine based on the three-degree-of-freedom 6PRR redundant parallel mechanism. The mechanism consists of a moving platform, a fixed platform, and 6 identical PRR ( P is the moving pair, R is the rotating pair) branch chain. Each PRR motion branch chain is composed of three motion pairs connected with two components. Among them, the movable platform and the fixed platform are respectively connected with the PRR motion branch chain through 6 identical rotating pairs R and 6 identical moving pairs P. The position and posture of the moving platform can be changed by controlling the expansion and contraction of the moving pair of the moving branch chain.

The performance and working space of the experimental platform of the plane mechanism cutting machine are greatly affected by the overall size of the mechanism and the length of each movement branch chain. Therefore, it is necessary to determine the overall size of the experimental platform and the length of each branch chain. The base of the 6PRR parallel mechanism is used to connect each branch chain and the basic components of the moving platform. The base remains stationary during the operation of the mechanism. In order to prevent the connecting rod from deforming due to excessive force when the mechanism moves, a universal ball is added under the movable platform (on the base), as shown in Figure 3, in order to support the movable platform. The branch chain is composed of two rods and three kinematic pairs. The designed PRR branch chain structure diagram. The size of the support chain rod is set at 240mm, using No. 45 steel. Figure 5 is the structure diagram of the moving platform. The six pivoting auxiliary hinge points are evenly distributed along the circumferential array, so that the force on the moving platform of the mechanism is more uniform and stress concentration is reduced. No. steel.

The moving pair P in the kinematic branch chain can choose hydraulic cylinder or ball screw according to the actual situation. Considering the actual working conditions, this paper adopts a ball screw mechanism. Compared with ordinary trapezoidal sliding screws, ball screws have the following characteristics: high positioning accuracy, high transmission efficiency, and long service life.

Parallel mechanisms are widely used in modern manufacturing due to their advantages of fast speed, high motion accuracy, and high structural rigidity. The use of redundant drive can effectively avoid the singularity of the parallel mechanism and improve the dynamic performance of the mechanism to a certain extent. CNC fiber laser cutting machine has the advantages of high cutting accuracy, fine slitting, good cutting quality and noise-free cutting. It is a technology with more development prospects and industrial application background in laser processing technology. High-speed cutting puts forward higher requirements on the dynamic performance of the machine tool structure. The better the dynamic performance of the machine tool structure, the stronger its anti-vibration ability and the higher the machining accuracy. It is of great significance to apply redundant parallel mechanisms with high precision, fast response, and easy control in the field of planar laser cutting. Because of the many advantages of redundant parallel mechanisms, it has attracted the attention of many scholars and achieved fruitful results. Dong Chenglin et al. analyzed the kinematics of the 4-UPS/UP redundant parallel mechanism, and compared the kinematic performance of the 3-UPS/UP parallel mechanism with the local kinematics evaluation index. A three-degree-of-freedom redundant drive parallel mechanism is proposed, and kinematics analysis is carried out. A planar two-degree-of-freedom redundant drive parallel mechanism is proposed, and the working space of the modified mechanism is analyzed. A new type of 4-PUS-UPS redundant parallel mechanism is proposed. The kinematics performance of the mechanism is analyzed by introducing condition number, motion/force transmission performance and stiffness performance evaluation index. Et al. studied a 3-DOF redundant drive parallel mechanism for lower limb rehabilitation, and optimized the design variables of the mechanism with the help of genetic algorithm. The results showed that the optimized mechanism has good force in its working space. / Motion transmission performance. Liu Xiaofei et al. designed a driving force control algorithm based on neural network for the 6PUS+UP redundant parallel mechanism, which improves the coordination of each branch drive compared with the traditional driving method. However, there are few research literatures on the application of redundant parallel mechanisms in the laser cutting field, which cannot meet the needs of modern high-precision fiber laser cutting machine analysis and design.

Based on the three-degree-of-freedom 6PRR redundant parallel mechanism, this paper designs an experimental platform for a plane fiber laser cutting machine, which is intended to be used in experimental teaching of mechanical majors. First, determine the specific size of the fiber laser cutting machine mechanism, and use Adams to simulate the kinematics and dynamics through modeling. According to the simulation results, extract the key point data, modify and optimize the initial size, and build a complete three-dimensional model using Softworks. Based on ANSYS, finite element simulation analysis of the main components is carried out, and the structural strength is checked to ensure the safety and stability of the overall operation process.

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