Base on RPR/RP+2R+P robot design for machining aluminum alloy structural parts
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摘要: 新能源汽车是我国应对节能减排挑战的需要,发展前景巨大。针对新能源汽车车身主要采用铝合金材料,要求加工机床灵巧轻便,整体刚度适中,能够实现复杂曲面的精准成形等需求,提出一种基于RPR/RP平面并联的五自由度混联机器人构型。首先,建立RPR/RP+2R+P五自由度混联机器人基本构型,分析计算混联机器人的自由度,完成五自由度混联机器人的初始样机结构设计。其次,求解并联与混联构型位置的正反解以及速度雅可比。然后,求解五自由度混联机器人的位姿空间;以分支杆驱动力为优化指标,工作空间内机构运转不干涉为约束条件,采用Adams-Matlab联合仿真定量分析各结构参数对分支驱动力的影响,以线性回归算法进行数据拟合,完成初始样机的尺度优化。最后,以混联机器人整机及其关键构件的刚度为优化指标,采用有限元分析的探究方法对五自由度混联机器人初代样机实现递进式的结构调整,对整机进行模态分析以得到机器人振动特性。在满足刚度要求的前提下,采取少分支构型降低制造成本,加工过程可视,为针对轻薄结构件加工的混联机器人设计提供了新思路。Abstract: New energy vehicles are the needs of China to cope with the challenges of energy conservation and emission reduction, and have great development prospects. Aiming at the problem that aluminum alloy is mainly used in the body of new energy vehicles, which requires that the machine tool is dexterous and lightweight, the overall stiffness is moderate, and the precision forming of complex surfaces is realized, a five degree of freedom hybrid robot configuration based on RPR/RP plane parallel is proposed. Firstly, the basic configuration of RPR/RP+2R+P 5-DOF hybrid robot is established, the degree of freedom of the hybrid robot is analyzed and calculated, and the initial prototype structure design of the 5-DOF hybrid robot is completed. Secondly, the forward and inverse solutions of parallel and hybrid configuration positions and velocity Jacobian are solved. Then, the pose space of the 5-DOF hybrid robot is solved ; taking the driving force of the branch rod as the optimization index, and the non-interference of the mechanism operation in the working space as the constraint condition, Adams-Matlab co-simulation was used to quantitatively analyze the influence of various structural parameters on the driving force of the branch, and the linear regression algorithm was used for data fitting to complete the scale optimization of the initial prototype. Finally, taking the stiffness of the hybrid robot and its key components as the optimization index, the finite element analysis method is used to realize the progressive structural adjustment of the initial prototype of the 5-DOF hybrid robot. The modal analysis of the whole machine is carried out to obtain the first six-order vibration characteristics of the robot. Under the premise of meeting the stiffness requirements, the new five-degree-of-freedom hybrid robot for aluminum alloy structural parts processing is beneficial to reduce the manufacturing cost and better realize the visualization of machining process. It provides a new idea for the design of hybrid robot for light and thin structural parts processing.
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Key words:
- aluminum parts machining /
- hybrid machine tool /
- scale optimization /
- virtual simulation
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表 1 混联机器人设计指标
设计参数 设计要求 工作空间/(mm×mm) 600 ×300 的椭圆形区域 分支最大速度/(m/min) 30 上下移动轴最大速度/(m/min) 50 空间定位精度/mm ≤0.05 重复定位精度/mm ≤0.02 主轴功率/kW 12~18 表 2 D-H参数表
连杆i 连杆扭角
$\alpha _\left( {i - 1} \right)$连杆长度
$a_\left( {i - 1} \right)$关节偏置
距离${d_i}$关节转角${\theta _i}$ 1 0 0 0 ${\theta _1}$ 2 90 0 $0$ ${\theta _2}$ 3 −90 0 $d$ 0 表 3 混联机构结构参数表
组数 L1 L2 组数 L1 L2 1 740 400 9 820 400 2 740 440 10 820 440 3 740 480 11 820 480 4 740 520 12 820 520 5 780 400 13 860 400 6 780 440 14 860 440 7 780 480 15 860 480 8 780 520 16 860 520 表 4 L1=740 mm参数下的曲线数据
组数 参数L2/mm 1 400 2 440 3 480 4 520 表 5 振动频率表
振型阶数 1 2 3 4 5 6 振动频率/Hz 20.628 45.389 49.3 51.688 54.536 60.5 -
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