低频复合振动钻削装置

1.两种单纯振动钻削的不足之处低频振动钻削一般都是采用轴向和扭转两种振动方式。轴向振动刀具对工件易产生轴向的冲击负荷,降低了工艺稳定性,同时要求刀具的刚性要好,否则易折断。扭转振动钻削是刀具与工件不分离的一种断续切削方式,因此切削热和摩擦热都集中在刀刃附近。刀具耐用度下降,工件易产生热变形。我们在实验中发现由于各种工件的材料的切削性能不同,工艺参数也不相同;有时由于切屑的积压划伤孔的表面,严重的则使刀具断裂,又由于进给量小,使生产效率不高。在此种情况下,采用低频振动切削是一种有效的改善措施。     

低频扭转振动钻削参数选择

介绍了低频扭转振动的实验装置，分析了切屑的大小与工艺参数的关系，通过钻削加工实验，得以证明，选用较小的进给量，中等切削速度，大振幅，有利于小深孔钻削加工的断屑和排屑，从而保证和提高了小深孔钻削加工的质量，有利于低频扭转振动工艺得到更广泛的应用。     

TC4钛合金低频振动钻削切屑形态和钻削力研究

为研究TC4钛合金低频振动钻削过程中切屑形态与钻削参数和振动参数对钻削力(轴向力和扭矩)的影响规律,基于一种自主研制的低频振动刀柄,分别采用单因素法和正交试验法对钛合金进行了低频振动钻削试验,分析了不同钻削条件下的切屑形态和钻削力,建立了轴向力和扭矩的经验公式,并对钻削力的影响因素进行直观分析与方差分析。结果表明:试验系统在低频振动钻削TC4钛合金时,振幅与进给量之比接近临界断屑值0.81时断屑可靠,排屑顺畅;低频振动瞬时钻削力呈现出规律的正弦波形,钻削力动态分量远大于普通钻削,轴向力和扭矩均值可比普通钻削分别降低10%～15%和15%～20%;进给量对钻削力影响最为显著,振幅次之,钻削速度影响最小;建立的振动钻削经验模型误差保持在10%以内,可以较为准确地对该试验系统所选参数范围内的钻削力进行预测。     

机械式低频振动钻削技术的研究进展

普通的钻削加工已不能满足大量难加工材料的加工要求,振动钻削加工技术在该背景下应运而生。机械式低频振动钻削技术是振动钻削技术的分支,经过各国专家学者的试验论证,相比普通钻削,其孔加工精度明显提升,振动钻削加工技术必将成为今后研究的重点方向。文章概述了振动钻削加工技术的基本原理、特点及研究现状,总结了当前研究中存在的主要问题,并对其今后的发展做了展望。     

低频振动钻削时微小钻头钻入横向偏移的研究

根据振动理论对低频振动钻削减小微小钻头钻入横向偏移机理进行了理论分析,阐明了微小钻头劝钻入的动力学特性,并在理论分析基础上对微小钻头钻入定位误差进行了实验研究。结果表明,振动钻削从根本上改变了钻入机理,使普通钻削的连续切削过程转变为断续的脉冲式削过程,因而提高了钻入定位精度。     

低频振动钻削提高微小钻头寿命机理的研究

根据振动理论对低频振动钻削提高微小钻头寿命的机理进行了理论分析与试验研究,阐明了低频振动钻削时微小钻头扭转振动的动力学特性。     

低频振动钻削精密深孔实验分析及振动装置的研制

根据低频振动钻削精密深孔实验进行分析，研制了一种新型复合振动装置，可作为机床附件使用。     

轴向低频振动辅助皮质骨钻削的钻削力和温升

为了研究轴向低频振动钻削方式在皮质骨钻削中对钻削力和温升的影响,基于一种自主研发的低频振动钻削设备,对常规和轴向低频振动辅助皮质骨钻削的钻削力和温升进行了实验,建立了钻削力和产热速率模型.实验结果表明:轴向低频振动钻削方式的进给力和转矩明显减小,温升降低了3～5℃;通过统计方法确定主轴转速是影响钻削力和温升的最显著因素...     

低频扭振钻削加工

振动切削工艺的振动方式有两种,如图1。一种是轴向振动。它的进刀方向和振动方向相同,因此,刀具的切削刃对工件产生周期性的冲击,刀刃易出现崩刃的现象,会降低刀具的使用寿命。所以这种方式适合于象铝这样软材料的深孔加工(如图1a)。另一种是用枪钻进行低频扭转振动钻削(如图1b),这是一种刀具与工件不分离的断续切削方式,可以得到理想的振动钻孔的效果,因此对于难以加工材料均可采用低频扭振钻削方式。 一、机械扭振系统 利用偏心机构来实现扭转振动(如图2),偏心距可调,可改变振幅的大小。本装置采用100Hz振动频率,由电机带动偏心轴转动,偏心轴使摆杆上下摆动,摆杆和振动轴、枪钻固定连接,从而实现枪钻扭转振动。     

Residual stress fluctuates periodically via the workpiece rotation phase during low frequency vibration cutting

The turning process is a standard machining process employed in diverse sectors. However, it produces long continuous chips that can affect the efficiency of the process, accelerate the tooling's wear, or damage the machined surface. As a solution, low frequency vibration cutting synchronizing with the spindle rotation has recently been developed as a new machining method in turning operation. It applies vibrations in the tool feed direction and can synchronously control the applied vibrations and the spindle rotation. It can also effectively divide the long continuous chips generated by the turning process and has the potential to reduce thermo-mechanical load on the tool by periodically enabling the tool to leave the workpiece due to the vibrations. Low frequency vibration cutting, the cutting characteristics of which differ from those of conventional turning, induces residual stresses in the machined surface; however, the properties of these stresses have not yet been studied. Residual stress can have both beneficial and negative effects on the fatigue life of products. While compressive residual stress increases the fatigue life of the product, tensile residual stress facilitates the growth of fine cracks on the product's surface and reduces fatigue life. Therefore, it is important to understand the characteristics of the residual stress developed on a machined surface. In this study, an annealed 0.45% C steel bar was machined via straight turning of the vibration cutting process synchronizing with the spindle rotation, and the residual stress on the finished surface was measured. Particular focus was placed on analyzing the effects of the spindle phase on the characteristics of the residual stress inside the machined surface, especially the effects of the number of vibrations per spindle rotation, D, which is a unique parameter defining the vibration condition. Our results revealed that the residual stress varied depending on the position of the finished surface owing to the change in feed with the spindle phase during the process. Furthermore, D was observed to heavily influence the distribution of the residual stress on the finished surface. By means of adjusting its value, the residual stress value could either fluctuate periodically according to the phase of the workpiece or not fluctuate.     

超声振动切削小孔的工艺研究

对超声振动切削小孔的工艺进行研究。通过对孔径φ0.2～0.5mm的小孔进行实验和分析,并研究了振动切削小孔的工艺效果及切削机理,解决了小孔加工的一系列难题。     

Modelling of viscoelastic damper support for reduction in low frequency residual vibration in machine tools

Residual vibrations deteriorate the accuracy and productivity of precision machine tools. Rocking vibration is excited by feed motion. Rocking vibration is the mode in which the entire machine vibrates and is the main source of residual vibrations at low frequencies. The characteristics of rocking vibration are influenced by the characteristics of the machine support structure. Thus, it is necessary to increase the damping of the machine support structure to reduce the residual vibrations caused by rocking vibration. In addition, it is important for machine tools to be stiff to reduce vibrations caused by the acceleration of feed drives. Conventional passive damper supports decrease the stiffness of a machine support structure while increasing the damping. Consequently, a passive viscoelastic damper system is developed to increase support damping without decreasing stiffness by focusing on the horizontal component of rocking vibration. However, the proposed damper damping capacity has a magnitude dependency. This makes it difficult to quantitatively determine the damper area in machine tools to reduce rocking vibrations to the required level. In this study, the developed damper is modeled using a viscoelastic four element model. Because of the nonlinearity of the model, an iterative time domain calculation method is introduced for the simulation. This method enables us to quantitatively estimate the effect of the damper on the machine tool. Based on the model proposed in this study, the proposed damper system can be applied to various machine tools to reduce the residual vibration without adjusting the damper area on the machine tool by a trial and error method.     

低频振动攻丝提高加工精度的试验研究

根据振动理论对低频振动攻丝提高加工精度的动力学机理进行了理论分析和试验研究 ,阐明了低频振动攻丝时丝锥扭转振动的动力学特性。     

低频变参数振动钻削微孔控制技术的研究

振动钻削在钻削过程的不同区段 ,其特征和钻削机理不同 ,对振动参数的要求也不一样。针对这一问题 ,提出变参数振动钻削这一方案 ,并研制了一套低频变参数振动钻削微孔控制系统 ,明显改善振动钻削的效果     

周向振动钻床钻夹头整体松脱解决方法研究

分析了周向振动钻床钻夹头整体从钻床主轴上松脱下来的原因,提出了极限摆振圆频率的概念,给出了极限摆振圆频率的计算公式．用事例验证了公式的正确性。找出了解决这一问题的办法,并提出了一些设想。实验表明,该方法简便、有效、切实可行。     

外排屑深孔钻削 DF系统的设计与研究

对外排屑深孔钻削DF系统的原理及装置进行了研究,对外排屑深孔钻削DF系统的参数选择及使用时注意事项进行系统地阐述。并设计制造出外排屑深孔钻削DF装置。经实验研究证明可有效的解决枪钻钻削过程中排屑等问题。     

微孔的超声振动钻削技术与工艺效果

介绍了一种超声振动钻削方法,并通过对孔径0.2～0．5min的微孔进行对比实验,分析研究了振动钻削的效果和切削机理,解决了微孔加工过程的一系列难题。     

无源伺服反馈多输出低频振动传感器

介绍了一种无源多输出低频振动传感器,可同时测量加速度和速度。利用无源伺服反馈控制技术,传感器呈现速度摆特性,但该速度摆不是通常意义上大阻尼状态的速度摆,对摆体特性进行了详细的数学分析,仅使用一种换能方式即实现了加速度和速度两组物理量的测量,证明了速度输出是速度摆速度计,加速度输出是速度摆加速度计。对传感器特性,尤其是加速度输出特性进行了较为详细的分析。最后,对传感器进行了测试,得到该传感器的加速度输出和速度输出在0.1~100 Hz有较好的频率响应特性,可以满足低频工程振动测量的需求,且实现了一只传感器同时测量加速度和速度两种物理参量。     

Using workpiece vibration cutting for micro-drilling

The purpose of this paper is to investigate the effects of assisted vibration on the drilling quality of aluminium alloy (Al 6061-T6) and structure steel (SS41). In the past, research methodology of vibration drilling on small-diameter holes has mainly involved vibrating from the spindle side. In this paper, a new approach to obtain the desired vibration is proposed from the workpiece side, by a self-made, vibrating worktable. Through extensive experiments with a twist drill size of 0.5 mm, we found that hole oversize, displacement of the hole centre, and surface roughness of the drilled wall could be improved with the increase of vibrating frequency and amplitude. Roundness of the drilled hole could also be improved when high amplitude and proper frequency are imposed.