【作者】 刘丰；

【导师】 于恩林；

【作者基本信息】 燕山大学 ， 机械设计及理论， 2009， 博士

【摘要】 钢管的连续生产过程中,在线切断设备是整个生产线中的关键设备之一。目前,一般所采用的管材切断方法存在许多问题。由于管材断面呈空心状,在切断过程中很难保证切口质量。为了提高管材的切口质量,圆截面管材无芯旋转滚压式剪切是近年出现的新型切断技术。滚切机是利用三把带有楔角的圆盘形滚切刀片,采用滚动压入的方法将管材切断。由于采用了滚压无屑剪切,刀具的滚切行程略大于管材壁厚即可切断管材,因而效率高(尤其是对于大直径管材)。不仅可以保证管材切口质量,还实现小噪音、无切屑、无毛刺切管,简化了生产工艺、降低了生产成本,改善了生产环境。本文介绍了新型滚压式剪切机的工作原理及结构。根据其特点,对系统进行了适当的简化,建立了滚切机横向振动的力学模型。用柔度系数法建立了系统的运动微分方程。得出了该设备的固有频率和主振型,求解了由转子质量偏心引起的失衡激振响应,分别求解了系统在无阻尼和有阻尼时的不平衡激振响应,绘制了响应曲线图,讨论了转子的质量偏心距和系统阻尼比对系统激振响应的影响规律。滚压剪切过程属于金属的塑性大变形和韧性断裂,所以使得对这一过程的分析非常困难。根据尖楔形体压入半无限体的滑移线解法,对钢管的滚压切断进行了理论分析,得出了滚切力计算公式及钢管与刀具接触面积公式。为了更加充分的发挥管材滚压式剪切机的优点,分析了在剪切过程中影响切口质量和刀具应力的一些因素。利用大变形有限元的基本理论,以管材切口质量和刀具应力为研究目标,以DEFORMTM 3D有限元分析软件为平台,对管材滚压剪切过程进行了模拟仿真。得到了滚切力行程曲线,找出了影响滚切力的各种因素,分析了影响切口质量和刀具应力的各种因素,确定了合理工艺参数匹配:滚切力值、刀具形状、单圈进给量等。为了实际生产应用时查询方便,本文建立了各参数对滚切过程影响的查询数据库。针对管材滚切实验研究,设计了一套测量滚切力和进给速度的实验系统。通过实验研究得到了滚切力与切入深度关系曲线、进给速度与切入深度关系曲线以及切口尺寸,与有限元计算结果相比较,两者基本吻合,证明了利用有限元数值模拟管材滚切过程是可靠的。以有限元模拟结果为基础分析的各工艺参数对管材滚切过程的影响是正确的。理论分析和实验研究表明,管材滚压剪切涉及到许多复杂问题,对这些问题进行分析和研究,可以揭示滚切过程的变形机理和刀具破坏机理,有助于控制管材切口特征及改善刀具受力状态,以便提出更为合理的滚切工艺。当然对相关问题还需要许多更深入细致的工作。更多还原

【Abstract】 The cutting machine is important equipment in producing and using the tube. There are a few problems in the tube cutting methods which are used normally. It is difficult to make cutting quality good because tube is hollow shape. For the sake of improving cutting quality, the tube roll-cutting is widely used in recent years. It uses three dishing blades to wheel on the tube exterior surface and cut into the material gradually. In the whole process, the blades turn around the tube axis and spins about their own axis as well. Because the blade stroke in the radial direction is just a little larger than the tube wall thickness, the size of the cutting tool can be reduced. In the roll-cutting process, there is no noise and no burrs exist. The tube roll-cutting not only samplifies the product process, but also improves the working environment.The roll-cutting principle and schematic arrangement of the roll-cutting machine is demonstrater in the paper. According the roll-cutting machine’s principle of work and the structure feature, the machine has been simplified. The roll-cutting system transverse vibration mechanics model has been established using the flexibility method of correlates. The natural frequency and first mode shape has been calculated. The imbalanced dynamic response caused by the mass bias with and without the damping has been solved. The response diagrams of curves have been drawn up. The rotor mass bias moment and the system damping ratio to the system dynamic response influence rule has been discussed.The large plastice deformation and ductile fracture happens in the roll-cutting process. It’s very difficult to calculate the cutting process. This paper has made the theoretical analysis using the theory of wedge indentation of ductile material. The equations of the cutting force and contacted area have been obtained.For the sake of taking the advantage of the roll-cutting machine and removing some bed factors, the process of roll-cutting has been simulated on the basis of the principle of large deformation FEM by using DEFORMTM 3D program. The relationship between the cutting force and cutting depth has been demonstrated. The influences of process parameters on the cutting force, cutting quality and balde stress have been found out. The reasonable parameters match has been obtained. The database of the effect of process parameters on the roll-cutting process has been founded for the convenience of inquiry.The author has designded an experiment system which is used to measure the roll-cutting force and feed speed. The curves for the cutting force with cutting depth, feed speed with the cutting depth and the dimension of fraction have been obtained using the experimental method. The results of the FE analysis are in agreement with the results of the experiment, through comparison between the simulated and measured result. It verified the validity of the simulation. By studying the cutting force, the effects of process parameters on the cutting force can be obtained. It is the foundation of the blade stress analysis.The theoretical analysis and experimental research indicate that there are many complicated problem involved in the roll-cutting process and researches on these problems can reveal mechanisms of deformation and balde failure. It is helpful to get a good cutting quality and improve the blade stress state. Also, it is useful to propose new cutting process. Of course, it is required that much profound and detail work of roll-cutting process will be done in the future.更多还原