渐进式软固结磨粒气压砂轮光整加工研究

发布时间：2018-08-22 19:24

【摘要】：模具制造中的光整加工是对工件的尺寸精度和表面质量进行精密修正,光整加工约占整个制造时间的40-50%。对于激光强化技术在模具领域的应用,基于软固结磨粒气压砂轮的光整方法能够解决激光强化模具表光整加工中高硬度、高耐磨性和复杂自由曲面的技术难题。由于缺乏对软固结磨粒表面形貌及光整加工表面的研究,尚未有一种有效的模型进行表面加工仿真分析。前期光整实验结果表明,软固结磨粒群出现大量脱落现象,且磨粒脱落速度大于粘结剂脱离速度,这大大降低了磨粒的有效加工参与率,影响了光整效率及加工质量。为实现模具激光强化表面的高效精密自动化光整加工,本文将在现有软固结磨粒气压砂轮研究的基础上,研究构建软固结磨粒气压砂轮表面形貌模型及光整加工模型,对实际表面加工进行仿真预测;优化改进软固结磨粒气压砂轮的组构,提高激光强化模具表面的光整效率和加工质量。本文内容主要从以下几个方面展开:(1)针对软固结磨粒气压砂轮接触表面形貌的构建问题,基于砂轮表面的特征及磨粒-工件接触行为特征,利用随机域重构建表面形貌模型,建立一种非高斯型软固结磨粒气压砂轮表面形貌模型,可通过实验给定参数模拟生成相应表面形貌以进行工件表面加工的仿真。(2)针对表面磨损和磨粒脱落等问题,改进传统气压砂轮,建立一种改良的渐进式软固结磨粒气压砂轮,以克服磨粒脱落和钝化、更换砂轮头加工时的低效和重置定位等问题,利用逐层加工的思想,拓宽加工粗糙度区间,提高加工效率,提升加工质量。(3)构建渐进式软固结磨粒气压砂轮的多层弹性体模型,对充气压力及旋转速度进行动态仿真,优选充气压力为0-0.1MPa、转速为1500rpm等加工参数为工艺参数。(4)针对软固结磨粒上单颗磨粒及气压砂轮的整体运动轨迹,建立软切削磨粒与工件表面微凸体的相应联系,添加表面材料硬度系数、微凸体去除模型、材料去除约束等,构造软固结磨粒气压砂轮光整工件表面的加工模型,通过实验给定加工参数,仿真形成相应工件表面。(5)针对加工目标,设计相应的实验方案,搭建面向激光强化表面的软固结磨粒气压砂轮加工实验平台,制备改进的渐进式软固结磨粒气压砂轮;通过光整实验,对加工中的材料去除及表面质量进行分析,验证砂轮表面形貌模型和光整加工模型的正确性;同时,对自由曲面进行光整加工,证明软固结磨粒气压砂轮对激光强化表面初期光整加工的有效性;对比传统气压砂轮及渐进式气压砂轮,渐进式磨粒层不仅优化磨粒脱落的问题,并且磨削过程过渡连续且平缓,渐进式气压砂轮的加工工件表面质量优于手动更换单层气压砂轮且加工效率提高34.6%。
[Abstract]:The finishing process in mould manufacturing is to correct the dimension accuracy and surface quality of the workpiece precisely, and the finishing process accounts for about 40-50% of the manufacturing time. For the application of laser hardening technology in the field of mould, the finishing method based on the pressure grinding wheel of soft bonded abrasive particles can solve the technical problems of high hardness, high wear resistance and complex free-form surface in the surface finishing of the mould strengthened by laser. Due to the lack of research on the surface morphology of soft bonded abrasive particles and surface finishing, there is not an effective model for surface processing simulation analysis. The results of early finishing experiments show that a large number of abrasive particles are shedding and the velocity of abrasive particles falling off is higher than that of binder, which greatly reduces the effective processing participation rate of abrasive particles and affects the finishing efficiency and processing quality. In order to realize the high efficiency and precision automatic finishing of mould surface strengthened by laser, the surface morphology model and finishing model of air pressure abrasive wheel with soft consolidation grain are studied and constructed on the basis of the existing research on the air pressure grinding wheel of soft consolidated abrasive particles. The simulation prediction of the actual surface processing is carried out, and the fabric of the air pressure grinding wheel for soft consolidated abrasive particles is optimized to improve the finishing efficiency and processing quality of the surface of the mould strengthened by laser. The main contents of this paper are as follows: (1) aiming at the construction of contact surface topography of soft bonded abrasive pneumatic grinding wheel, based on the surface characteristics of grinding wheel and the contact behavior of abrasive particle and workpiece, a surface topography model is constructed by re-constructing the model in random domain. A surface morphology model of non-Gao Si soft bonded abrasive pneumatic grinding wheel is established. The corresponding surface morphology can be generated by simulating the given parameters. (2) aiming at the problems of surface wear and abrasive particle shedding, etc. By improving the traditional pneumatic grinding wheel and establishing an improved progressive soft consolidation abrasive particle pneumatic grinding wheel, the problems of abrasive shedding and passivation, the low efficiency and reset position of replacing the grinding wheel head are overcome, and the idea of layer by layer machining is used. Widen machining roughness range, improve machining efficiency and improve machining quality. (3) the multi-layer elastomer model of progressive soft bonded abrasive pneumatic grinding wheel is constructed, and the dynamic simulation of inflatable pressure and rotation speed is carried out. The processing parameters such as air pressure 0-0.1MPa and rotational speed 1500rpm are selected as the process parameters. (4) according to the whole motion path of single abrasive and pneumatic wheel on soft consolidated abrasive, the corresponding relation between the abrasive particles in soft cutting and the micro-protrusions on the workpiece surface is established. The hardness coefficient of the surface material, the removal model of the microconvex body, the material removal constraint and so on are added to construct the machining model of the surface of the workpiece with the air pressure grinding wheel of the soft consolidated abrasive grain, and the machining parameters are given through the experiment. The corresponding workpiece surface is formed by simulation. (5) aiming at the machining target, the corresponding experimental scheme is designed, and the experimental platform for machining the soft consolidated abrasive particle pneumatic grinding wheel for laser strengthened surface is built, and the improved progressive soft consolidated abrasive pneumatic grinding wheel is prepared. Through finishing experiment, material removal and surface quality are analyzed to verify the correctness of grinding wheel surface morphology model and finishing model. It is proved that the air pressure grinding wheel of soft bonded abrasive particles is effective in the initial finishing process of laser strengthened surface, and compared with the traditional pneumatic grinding wheel and the progressive air pressure grinding wheel, the progressive abrasive layer not only optimizes the problem of abrasive particle shedding, The grinding process is continuous and smooth, and the surface quality of the progressive pneumatic grinding wheel is better than that of replacing the single-layer pneumatic grinding wheel manually, and the machining efficiency is increased by 34.6.
【学位授予单位】：浙江工业大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TG580.6

【相似文献】