A critical review on self-lubricating ceramic-composite cutting tools

Self-lubricating ceramic cutting tools have recently gained considerable attention as the tool wear in cutting hard-to-cut materials greatly affects the production cost, integrity of the machined surface, and productivity. In an attempt to compile the progress made in this important research area, a critical review has been performed covering a range of aspects. These include the current research trends and the need for self-lubricating ceramic tools, identification of prospective high-temperature solid lubricants and their limitations followed by a presentation of recent experimental and numerical work conducted related to self-lubricant ceramic cutting tools. Various lubrication mechanisms involved in the cutting process are also examined to identify general tribological response under various tribo-systems, which is expected to provide useful directions for the researchers and cutting industry. The current and emerging synthesis techniques are discussed in detail and compared with respect to ceramic cutting tools. Finally, some research gaps and future directions are suggested that could lead to optimum design and development of innovative self-lubricating ceramic tools.     

磁性辊轮驱动装置在切割生产线中的应用

随着汽车及机床行业的发展,板料涂油工艺在汽车零部件生产中应用广泛,从而导致板料在自动切割生产过程中极易打滑跑偏,无法保证传输精度,本文所阐述的磁性辊轮驱动装置从根本上有效解决了此问题,在切割生产线中有广泛的推广价值。     

Tribological behavior of αı/βı-SiAlON-TiN composites

There are limited studies on the tribological properties of SiAlON-TiN composites. Therefore, in the present study, tribology tests were conducted on a number of α^?/β^?-SiAlON-TiN composites with different α^?/β^?-SiAlON phase ratio and TiN content, fabricated with unique compositional design. The influence of α^?/β^?-SiAlON phase ratios, microstructure, mechanical properties and TiN content on friction and wear behavior was investigated and wear mechanisms were explained. Tribology tests were conducted on computer controlled tribometer under dry unlubricated ambient conditions with a linear reciprocating movement in a ball-on-disc sliding wear configuration and test parameters kept as constant. It was observed that TiN addition (17?wt.%) did not change the friction (CoF) of SiAlON and wear rate and wear volume were observed to increase. Wear mechanisms showed differences with α^?:β^?-SiAlON phase ratio. Fracture toughness had very pronounced effect on wear resistance.     

采煤机截割机构截齿受力监控系统

针对采煤机截割机构截割作业过程中作用在截齿上的截割阻力和冲击较大,导致截齿磨损严重、使用寿命短、经济性差的问题,以应变传感器为基础提出了一种新型的截齿受力监控系统,对截割作业过程中截齿的受力进行实时监控。应用结果表明,该监控系统能够精确对截齿受力进行监控,并对截齿的磨损状态和失效状态进行有效判断,及时对其进行调整维护,可以提升截齿截割过程中的截割效率,增加截齿的使用寿命。     

Cutting performance and wear mechanism of Sialon ceramic tools in high speed face milling GH4099

This work aims to reveal the cutting performance and wear mechanisms of Sialon ceramic tools for the high-speed face-milling of GH4099, with the goal of improving this process as well as designing more advanced ceramic cutting tools in the future. At the outset of this study, several single-factor experiments were designed with speed as a variable to gather various data on such tools. Failure patterns and tool life curves were first obtained through cutting tests. Afterwards, the tools were split at their place of wear (middle of notch and 1/2 depth of cut) to prepare for further analysis. Wear morphology and element composition distribution in the depth direction of the corresponding interface were then analyzed using a field emission scanning electron microscope (FE-SEM) and energy dispersive spectrometer (EDS) to explore potential diffusion and/or chemical wear. Finally, studies were conducted into the tools’ chemical wear under specific cutting conditions, finishing with a theoretical verification based on the thermodynamic principle of chemical reactions. This research discovered that notch wear was the main failure pattern for the high-speed face-milling of GH4099 under the suitable cutting conditions. Overall, the optimal cutting speed was 1000 m/min, with a tool life of about 3 min. Compared with cemented carbide tools, the machining efficiency for Sialon ceramic tools increased by over a factor of 16. The wear mechanisms for such tools demonstrated a mixture effect of abrasive, adhesive, diffusive and chemical wear. Diffusive wear mainly occurred in their flank faces, but did not constitute the main mechanism of notch wear; chemical wear proved to be a key reason for notch wear at higher temperatures. Based on the aforementioned research, this paper concludes with a proposed comprehensive model for notch wear.     

Chip geometry and cutting forces in gear power skiving

This paper describes a new virtual model for predicting the uncut chip geometry and cutting forces in power skiving, which is a high-speed, versatile gear cutting process. The developed kinematic model is applied in a dexel-based solid modeling engine to extract three-dimensional uncut chip geometry, from which the two-dimensional cross section is obtained via Delaunay triangulation. Cutting velocities along discretized cutter edges are calculated and used to determine the effective rake and oblique angles. Then, force predictions are made using the oblique cutting model and validated using measurements from power skiving trials performed on a DMG MORI NT5400DCG mill-turn machine.     

A quick method for evaluating the thresholds of workpiece surface damage in machining

This paper proposes a Pendulum-Based Cutting Test (PBCT) methodology which allows quick cutting tests for surface integrity evaluation along with providing cutting energies associated with particular level of workpiece surface damage, this is backed by an unified cutting energy model that links damage level of machined surface with energy partition in the cutting area. PBCT method could rapidly define the energy transferred to the workpiece that incurs particular magnitude of surface damage without using conventional machine tools and monitor the cutting process while only limited amount of materials is required. A demonstration of the proposed method is presented for Inconel718.     

空气喷射辅助少量润滑对航空铝合金7050 T7451铣削力的影响

为了提高少量润滑的冷却润滑效果,提出了空气喷射辅助少量润滑的方法,并利用建立的空气喷射辅助少量润滑系统对航空铝合金7050-T7451进行铣削实验。通过采集切削力信号对干切削、不同切削液流量的空气喷射辅助少量润滑切削和湿式切削进行比较研究。结果表明:干切削条件下的切削力大于空气喷射辅助少量润滑的切削力,且随着切削液流量的增大,气液两相冷却润滑介质的润滑能力增强,导致切削力呈减小趋势;空气喷射辅助少量润滑与湿式冷却润滑两种条件下的切削力相比,总体来说前者小于后者,这一现象表明空气喷射辅助少量润滑的润滑效果优于湿式冷却润滑,但切削液的使用量仅为后者的3%。     

针对表面粗糙度和刀具振幅的切削用量优化研究

对进给量、切削速度和轴向切深这3个切削参数对工件表面粗糙度和刀具振动幅度的影响进行试验研究。采用BBD响应面法对6061铝工件进行端铣加工试验,并通过数学建模对试验结果进行分析。提出一种基于遗传算法的多目标优化方法来同时减小工件表面粗糙度和刀具振动幅度。建立能预报表面粗糙度和刀具振动的径向基神经网络模型,并通过试验验证其准确性。