渐进式粘磨层气压砂轮及软磨削试验

发布时间：2018-08-14 17:20

【摘要】：激光强化技术可大幅提高模具表面的硬度和耐磨性,因而在模具制造业中得到越来越广泛的应用。单一目数磨粒砂轮头加工工件的最高精度具有局限性,且加工工件粗糙度区间窄,实际光整加工中往往采用手动更换不同目数砂轮头的方式进行逐阶段加工,这种方法不符合自动化加工的目的,且加工效率低下。为了解决单层粘磨层气压砂轮存在的局限。本文提出和制备一种渐进式粘磨层气压砂轮,采用分层渐进抛光的思想,其粘磨层主要由80#、120#、180#3层不同目数磨粒粘结剂组成。不同目数粘磨层有其相应的光整加工区间,在光整加工中外层粘磨层脱落完成后,内层新的磨粒逐渐露出进行后续加工。该新型气压砂轮既避免了更换砂轮头时工件表面加工纹路的变化而影响表面质量,又大幅提高光整加工的效率和自动化程度。具体研究内容如下:1)通过对气压砂轮的组成材料进行分析:本文采用半球型气压砂轮结构,基体层外径40mm,并对橡胶基体进行短纤维增强;对不同成分、组成的粘磨层进行力学分析,得到最佳的橡胶层厚度3mm,粘磨层厚度2~2.5mm。通过分析粘磨层层数对制备效率和加工效率的关系确定3层粘磨层的最佳层数。2)通过气压砂轮动态接触过程中柔性变形的分析,建立渐进式粘磨层气压砂轮力学模型并对其进行仿真分析。通过改变转速和充气压力,分析转速和充气压力对各层应力和整体应变的影响,得出了气压砂轮工作时的危险面,并得出合适的加工工艺参数:充气压力P=0.1MPa和转速V=1250rpm,并验证设计的合理性。3)针对多层不同厚度、不同目数磨粒粘磨层的气压砂轮,提出一种渐进式粘磨层气压砂轮的制备方案。通过180#、120#、80#3种不同目数磨粒单层气压砂轮的表面加工质量实验和磨粒脱落量实验,确定不同粘磨层的厚度分别为2mm、0.21mm、0.3mm。对短纤维增强橡胶基体的制备和粘磨层的压制进行了进一步的阐述。通过KEYENCE VHX-600E数码显微镜观测了制备的气压砂轮粘磨层剖面图,不同粘磨层的厚度与理论值一致,误差均在5%以内。4)围绕渐进式粘磨层气压砂轮的材料去除特性展开研究,通过实验得出P=0.1MPa和V=1250rpm最合适的工艺参数,验证了仿真结果。在实际光整中,无需更换砂轮头,磨削过程平稳,减少了传统气压砂轮加工方式中由于更换气压砂轮而导致切削纹路的改变所造成表面质量的下降;同时较直接采用180#单层气压砂轮加工,新型的渐进式目数气压砂轮完成初期光整加工效率提高34.6%;较更换砂轮头方式进行加工,加工效率提高19%。本文的研究思路及成果为其他结构的渐进式粘磨层气压砂轮的制备和实现激光强化模具自由曲面的纳米级加工提供了一定的指导意义,具有一定的技术借鉴价值。
[Abstract]:Laser hardening technology can greatly improve the hardness and wear resistance of mould surface, so it is more and more widely used in die manufacturing industry. The maximum precision of machining workpiece with single mesh abrasive grinding wheel head is limited, and the roughness range of machining workpiece is narrow. In actual finishing, the manual replacement of different grinding wheel heads is often used to process the workpiece step by step. This method does not meet the purpose of automatic machining, and the processing efficiency is low. In order to solve the problem of single layer viscous grinding layer pneumatic grinding wheel. In this paper, a kind of progressive pressure grinding wheel is proposed and fabricated. The idea of layered progressive polishing is adopted. The adhesive layer is mainly composed of 80#Li 120 #Li #3 layers with different mesh number of abrasive particle binders. There are corresponding finishing zones in different mesh number of glued grinding layers. After the outer layer is finished, the new abrasive particles in inner layer are gradually exposed for subsequent processing. The new pneumatic grinding wheel not only avoids the change of workpiece surface processing grain when the grinding wheel head is replaced, but also greatly improves the efficiency and automation of finishing. The specific research contents are as follows: (1) by analyzing the composition of the pneumatic grinding wheel: this paper adopts the hemispherical pneumatic grinding wheel structure, the outer diameter of the matrix layer is 40mm, and the rubber matrix is reinforced by short fiber. The optimum thickness of the rubber layer is 3 mm and the thickness of the adhesive layer is 2. 5 mm. By analyzing the relationship between the preparation efficiency and the processing efficiency, the optimum layer number of the three layers is determined by analyzing the relationship between the layer number of the viscous grinding and the processing efficiency) and the flexible deformation of the three layers is analyzed during the dynamic contact process of the pneumatic grinding wheel. The mechanical model of progressive viscous layer pneumatic grinding wheel is established and simulated. By changing the rotational speed and charging pressure, the influence of rotational speed and inflation pressure on the stress and overall strain of each layer is analyzed, and the dangerous surface of pneumatic grinding wheel is obtained. The suitable processing parameters: inflatable pressure P=0.1MPa and rotational speed V1 250 rpm are obtained, and the rationality of the design is verified. 3) aiming at the pressure grinding wheel with different thickness and different mesh number of abrasive particles, a preparation scheme of the progressive pressure grinding wheel for the viscous layer is put forward. Through the experiments of surface processing quality and abrasive particle shedding of three kinds of monolayer air pressure grinding wheel with different mesh number, the thickness of different adhesive layer is determined to be 2mm / 0.21mm / 0.3mm. The preparation of short fiber reinforced rubber matrix and the pressing of gluing layer were further expounded. KEYENCE VHX-600E digital microscope was used to observe the profile of pressure-pressure grinding wheel. The thickness of different layer is consistent with the theoretical value, and the error is less than 5%. The most suitable process parameters of P=0.1MPa and V=1250rpm are obtained by experiments, and the simulation results are verified. In the actual finishing, the grinding process is stable without replacing the grinding wheel head, and the surface quality of the traditional pneumatic grinding wheel is reduced due to the change of cutting lines caused by the replacement of the pneumatic grinding wheel. At the same time, compared with the 180# single-layer pneumatic grinding wheel, the efficiency of finishing the new progressive pneumatic grinding wheel at the initial stage is increased by 34.6%, and the machining efficiency is increased by 19% compared with the replacement of the grinding wheel head. The research ideas and results of this paper provide a certain guiding significance for the preparation of the progressive viscous layer pneumatic grinding wheel with other structures and the realization of nanoscale machining of the free-form surface of the mould strengthened by laser, which has certain technical reference value.
【学位授予单位】：浙江工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG743

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