Robotic grinding is considered as an alternative towards the efficient and intelligent machining of complex components by virtue of its flexibility, intelligence and cost efficiency, particularly in comparison with the current mainstream manufacturing modes. The advances in robotic grinding during the past one to two decades present two extremes: one aims to solve the problem of precision machining of small-scale complex surfaces, the other emphasizes on the efficient machining of large-scale complex structures. To achieve efficient and intelligent grinding of these two different types of complex components, researchers have attempted to conquer key technologies and develop relevant machining system. The aim of this paper is to present a systematic, critical, and comprehensively review of all aspects of robotic grinding of complex components, especially focusing on three research objectives. For the first research objective, the problems and challenges arising out of robotic grinding of complex components are identified from three aspects of accuracy control, compliance control and cooperative control, and their impact on the machined workpiece geometrical accuracy, surface integrity and machining efficiency are also identified. For the second aim of this review, the relevant research work in the field of robotic grinding till the date are organized, and the various strategies and alternative solutions to overcome the challenges are provided. The research perspectives are concentrated primarily on the high-precision online measurement, grinding allowance control, constant contact force control, and surface integrity from robotic grinding, thereby potentially constructing the integration of “measurement – manipulation – machining” for the robotic grinding system. For the third objective, typical applications of this research work to implement successful robotic grinding of turbine blades and large-scale complex structures are discussed. Some research interests for future work to promote robotic grinding of complex components towards more intelligent and efficient in practical applications are also suggested.

Robotic grinding of complex components: A step towards efficient and intelligent machining – challenges, solutions, and applications

Due to the advances in the digitalization process of the manufacturing industry and the resulting available data, there is tremendous progress and large interest in integrating machine learning and optimization methods on the shop floor in order to improve production processes. Additionally, a shortage of resources leads to increasing acceptance of new approaches, such as machine learning to save energy, time, and resources, and avoid waste. After describing possible occurring data types in the manufacturing world, this study covers the majority of relevant literature from 2008 to 2018 dealing with machine learning and optimization approaches for product quality or process improvement in the manufacturing industry. The review shows that there is hardly any correlation between the used data, the amount of data, the machine learning algorithms, the used optimizers, and the respective problem from the production. The detailed correlations between these criteria and the recent progress made in this area as well as the issues that are still unsolved are discussed in this paper.

A review of machine learning for the optimization of production processes

State-of-the-art of surface integrity induced by tool wear effects in machining process of titanium and nickel alloys: A review

Abstract Fiber-reinforced composites have become the preferred material in the fields of aviation and aerospace because of their high-strength performance in unit weight. The composite components are manufactured by near net-shape and only require finishing operations to achieve final dimensional and assembly tolerances. Milling and grinding arise as the preferred choices because of their precision processing. Nevertheless, given their laminated, anisotropic, and heterogeneous nature, these materials are considered difficult-to-machine. As undesirable results and challenging breakthroughs, the surface damage and integrity of these materials is a research hotspot with important engineering significance. This review summarizes an up-to-date progress of the damage formation mechanisms and suppression strategies in milling and grinding for the fiber-reinforced composites reported in the literature. First, the formation mechanisms of milling damage, including delamination, burr, and tear, are analyzed. Second, the grinding mechanisms, covering material removal mechanism, thermal mechanical behavior, surface integrity, and damage, are discussed. Third, suppression strategies are reviewed systematically from the aspects of advanced cutting tools and technologies, including ultrasonic vibration-assisted machining, cryogenic cooling, minimum quantity lubrication (MQL), and tool optimization design. Ultrasonic vibration shows the greatest advantage of restraining machining force, which can be reduced by approximately 60% compared with conventional machining. Cryogenic cooling is the most effective method to reduce temperature with a maximum reduction of approximately 60%. MQL shows its advantages in terms of reducing friction coefficient, force, temperature, and tool wear. Finally, research gaps and future exploration directions are prospected, giving researchers opportunity to deepen specific aspects and explore new area for achieving high precision surface machining of fiber-reinforced composites. 

https://link.springer.com/content/pdf/10.1007/s11465-022-0680-8.pdf

Fiber-reinforced composites in milling and grinding: machining bottlenecks and advanced strategies

/pdf/fiber-reinforced-composites-in-milling-and-grinding-fhcdm1c7.pdf

In order to improve surface quality and reduce surface roughness of integrally bladed rotors (IBRs), the optimizations of grinding and polishing process parameters, such as abrasive size, contact force, belt linear velocity, and feed rate, are carried out in this study. Firstly, the optimal range of each factor is obtained by single-factor experiment, and a surface roughness prediction model is generated according to the central composite design experiments and quadratic regression design technology. Secondly, the optimal level of each factor is confirmed through the surface roughness prediction model, and the response surface of the optimal level of each factor is drawn using Matlab. Then, the optimum process parameters are determined by analyzing the response surface. Finally, the optimum process parameters are selected in the grinding and polishing experiments for IBR. The experimental results show that grinding and polishing with the optimum parameters obtained in this study enhances the machining quality significantly. The surface roughness of IBR improved greatly (nearly 25 %) compared with grinding using normal parameters.

Surface roughness prediction and parameters optimization in grinding and polishing process for IBR of aero-engine

This paper experimentally studies the low-velocity impact behaviors and residual tensile strength of carbon fiber reinforced plastics (CFRP) laminates. Firstly, the effects of four factors, i.e. impact angle, impactor diameter, the proportion of ply orientation and stacking sequence, on the impact responses of laminates are studied. The damage characteristics are evaluated by dent depth, delamination damage projection area (DDPA) and energy dissipation. Secondly, the tensile responses of the laminates after impact are investigated based on residual tensile strength (RTS). Finally, the correlations between the four damage evaluation criteria, i.e. dent depth, DDPA, energy dissipation and RTS, are sorted out. Experimental results demonstrate that the four factors have significant effects on the impact behaviors of laminates in different ways. The DDPA is negatively correlated with the dent depth of laminates, and the dent depth can be treated as an important reference for the RTS. Besides, a fracture phenomenon, i.e. a clear band of fiber fracture around the impact area after impact, has been observed and discussed.

Low-velocity impact behavior and residual tensile strength of CFRP laminates

Low-velocity impact damage research on CFRPs with Kevlar-fiber toughening

Due to their high stiffness and strength, composites are widely used in the aerospace industry. To manufacture composites, especially composites of free-form surface structure, process of robotic fibre placement (RFP) is widely used in industry. However, due to the complex geometry of the free-form surface, it is quite challenging to generate accurate roller paths for placing fibre on the surface for high composites quality. To address this problem, this work proposes an accurate roller path planning method using the differential geometry. The roller paths can ensure the specified small gaps and overlaps between two tows for high composite quality. This approach is applied to several examples, and their results verify the validity of this approach. It has great potential to be adopted in industry.

An accurate approach to roller path generation for robotic fibre placement of free-form surface composites

Surface quality and profile accuracy of the leading and trailing edges (LTE) have a direct influence on the performance and lifetime of an aero-engine. The artificial buffing polishing for LTE has the drawbacks of heavy workload, poor consistency, experience-dependence, and so on. To solve these problems, the five-axis abrasive belt flap wheel (ABFW) polishing method for LTE of an aero-engine blade is proposed in this manuscript. Firstly, the flexible deformation law of ABFW is studied based on the Hertz elastic contact theory. Then, the control system of the contact force is established to keep the stability of the material removal rate in ABFW polishing. Furthermore, the key technologies of LTE polishing path planning with ABFW such as path direction determining, row space determining, and tool posture calculating are studied. After that, the polishing path of LTE with ABFW is generated. Finally, the verification experiments are carried out. The results suggest that the ABFW flexible deformation law is reliable, and the proposed polishing method for LTE is feasible and effective.

Yaoyao Shi

Papers

Surface roughness prediction and parameters optimization in grinding and polishing process for IBR of aero-engine

Low-velocity impact behavior and residual tensile strength of CFRP laminates

Low-velocity impact damage research on CFRPs with Kevlar-fiber toughening

An accurate approach to roller path generation for robotic fibre placement of free-form surface composites

Five-axis abrasive belt flap wheel polishing method for leading and trailing edges of aero-engine blade