难切削材料深孔加工刀具液力自定心、自导向、自纠偏原理

Titanium alloys, super alloys and stainless steels are important materials. Besides, deep holes have important functions. But it is Difficult to make a hole in the material listed above because the cutting tool is easy to deform and deviate. As a result, the performance and life of many products are decided by the deep holes made. . A principle is put forward to make cutting tools located in deep hole centers, self guided, self-rectified with cutting fluids. When the cutting tools are used to drill titanium alloys, super alloys and stainless steels, they will still be in right places if this principle is applied..In this research, the deep hole cutting tools will be supported, located and rectified by wedge-shaped oil films during deep hole machining just as shafts are supported, located and rectified by oil films in hydrodynamic lubrication bearings. A positive cone is fixed with the drill. The rod connected with the drill is made with multiple spiral grooves to make the cutting fluids rotate round the the rod and keep the rod steady..After this research, the characteristics of the flow fields will be known, the forces and moments of the oil films acting on the cutting tools will be calculated, stiffness matrices and damping matrices of oil films will be discussed, the attenuation of vibration of the cutting tools will studied. Based on the forces, parameters of the oil films, cones and spiral grooves, constraint conditions and calculation rules of the optimization of the cutting tool system will be decided. .In conclusion, the novel principle is essentially different from the existing principle of deep hole machining, which has been existing for 200 years and has been widely used by countries all over the world. It can locate, guide, and rectify the cutting tools by simple structure along with existing cutting fluids, and will improve the straightness and the positional precision of deep holes.

难切削材料和深孔结构都具有重要的功能和较差的工艺性。在难切削材料上加工深孔，刀具容易走偏，其深孔精度是决定产品性能和寿命的关键因素之一。本项目研究深孔刀具液力自定心、自导向、自纠偏原理，为提高深孔加工精度提供理论支持。.项目借鉴滑动轴承动压润滑原理，以楔形油膜定位、引导、纠正深孔刀具；借鉴滑阀顺锥特性，在刀杆上设置顺锥以纠偏；借鉴陀螺原理，在刀杆上加工螺旋槽，使切削液旋转以稳定刀具。通过本研究掌握流场特征和系统的动力学特性，求得流体对刀具系统的作用力及抗干扰能力系数，获得油膜的刚度矩阵、阻尼矩阵及油膜使刀具系统多维颤振衰减的规律。以楔形、顺锥、螺旋槽结构参数、切削液参数与材料的切削力为变量，建立多变量优化设计的约束条件和计算原则。.所提出的原理以切削液实时自动定位、纠正、稳定刀具，与已存在200年且为各国采用的深孔加工原理有本质的差别，可促进深孔加工在线纠偏难题的解决。

深孔加工刀具系统长径比大、刚度低，容易变形和走偏。当加工难切削材料时，变形和走偏更容易发生。难切削材料及其深孔结构常常用于国防、航空航天等高科技和新科技领域，存在于武器装备、大型机械、精密仪器等特殊设备中，一般具有独特的难以替代的功能。本研究提高深孔加工直线度、位置精度，对于发挥难切削材料的特殊功能具有重要意义。.本项目研究深孔刀具液力自定心、自导向、自纠偏原理，为提高深孔加工精度提供理论支持。项目借鉴滑动轴承动压润滑原理，以楔形油膜定位、引导、纠正深孔刀具；借鉴滑阀顺锥特性，在刀杆上设置顺锥以纠偏；借鉴陀螺原理，在刀杆上加工螺旋槽，使切削液旋转以稳定刀具。.基于流体动力润滑的楔形定心装置，其两端分别与钻头、钻杆固定连接，楔形部分与深孔孔壁形成三个楔形油膜。由于旋转运动和油液的黏度，油液从楔形间隙的大端流入，小端流出，引起油膜压力上升。本研究从雷诺方程出发，求得设置楔形结构后切削液沿径向和轴向的压力分布，液体的流速、流量和阻尼特性，使三个楔形油膜作用于定心装置，防止了定心装置及与其相连的钻头和钻杆的偏移，减小了所加工深孔的偏斜量。顺锥固定于钻头和钻杆，当切削液流过顺锥时，切削液由圆环形状变为锥环。当顺锥在深孔加工过程中偏离深孔轴线时，一侧油膜变薄，一侧油液变厚，通过准确计算得到：变薄的油膜产生更大的作用力，推动深孔加工刀具系统回到深孔中心。在钻杆表面设置螺旋槽，引导切削液沿深孔轴线运动的同时，环绕钻杆旋转，稳定钻杆、抑制偏斜。采用流体仿真，正交试验、BP神经网络算法，得到螺旋槽槽数、槽宽、槽深和螺旋角对液体最大作用力的影响，并进行了优化设计。.深孔刀具液力自定心、自导向、自纠偏实验过程中，深孔加工机床及其各部件运行正常，未发现额外的振动或声音，钻削深孔后，定心装置表面未发现明显的划痕或碰伤。采用现有加工方法，深孔偏斜量0.5mm/3.2m，采用本项目方法，深孔偏斜量0.4mm/3.2m。