The International Journal of Advanced Manufacturing Technology

This study proposes the use of a real-time non-uniform rational B-spline (NURBS) interpolator with a look-ahead function to handle numerous short linear segments. The short linear segments conforming to the continuous short block (CSB) criterion can be fitted into NURBS curves in real time. A modified maximum feedrate equation based on the geometric characteristics of the fitting curves and the dynamics of the servo control system has been derived in this paper. Taking advantage of the multi-thread design and the look-ahead function, the real-time NURBS interpolator can process enough G01 block information and complete feedrate planning before interpolation. In addition, the S-shaped jerk-limited acceleration method is adopted for smoother feedrate profiles. Two part shapes, which possess more than 1,000 short linear segments, are tested on our PC-based real-time control system. Both simulation and experimental results verify the feasibility and precision of the proposed interpolation algorithm.

In this paper, two process and die design methods for ball valve forming from stainless steel tubes are compared: one is the tube hydroforming method (THFM), and the other is the tube nosing method (TNSM). Simulations on hydraulic expansion, axial feeding, and tube nosing of the ball shell forming with the two methods using the program DEFORM-3D are carried out. The influence of the two methods on workpiece formability and wall thickness distribution of ball valve forming is examined. A tube nosing experiment is carried out with a SUS304 stainless steel tube at room temperature. An accepted product of ball valve satisfying the industrial demand is obtained using TNSM.

In this paper, we study the effect of various benchmark deadlock recovery strategies, and we find that each of these recovery strategies either results into another kind of deadlock or results into very high handling cost and long handling time. We also propose a new improved strategy in order to solve the shop deadlock problem through the use of both automated guided vehicle and a central buffer. To the best knowledge of the authors, till date, no research study has been performed to propose any such strategy in this regard or to study the effect of several deadlock recovery strategies altogether. Simulation result shows that the proposed strategy performs better than the existing benchmark recovery strategies and provides much improved solution to the shop deadlock problem, resulting into considerable reduction in handling time and cost and better handling of jobs in central buffer compared to various benchmark deadlock recovery strategies available in the literature.

The objective of this study is to propose a method for reverse engineering prismatic and free-form shapes. The primary focus is on feature-based parameterization of digitized geometries so that they can be further used in downstream MCAD (mechanical computer-aided design) applications. The study takes advantage of a 3D body scanner for rapid digitizing purpose to acquire denser point clouds with no more than three scans. Suggested are five basic steps towards successful reverse engineering prismatic and free-form shapes. They include acquisition of a raw point cloud data, processing of raw data, mesh generation, surface reconstruction, and feature-based parameterization. In this study, three different sample parts that include a mechanical nozzle, a hubcap, and a bucket seat, were reverse engineered to demonstrate the proposed methodology. This process was proven effective toward reconstruction of free-form NURBS (non-uniform rational B-spline) surfaces. It also proved efficient towards feature-based parameterization of prismatic shapes.

With the rising need to promote productivity that is based on quality, energy, and cost, it is imperative that cutting tools are not just selected on the basis of its suitability, but on its efficiency. It is particularly important that workpiece materials are aligned to specific cutting tools, to improve manufacturing costs, lead time, and quality of the overall product and to create flexibility. For this reason, a comparative study of the performance of high-speed steel and tungsten carbide cutting tools has been performed to determine the most suitable for the machining of a 304 Austenite Steel cylindrical bar. The tool wear of the cutting tools was selected as a measured to ascertain their performance in the turning operation. Response surface methodology was employed to analyzing the results and determining their optimal performance. From the study, the tungsten carbide tool recorded optimal parameters as follows: cutting speed 1303 m/min, feed rate 0.354 mm/rev, and depth of cut 0.458 mm with a tool wear of 1.173 mm and for the high-speed steel tool, cutting speed 1321 m/min, feed rate 0.208 mm/rev, and depth of cut 0.682 mm with a tool wear of 2.073 mm. The study judging from the tool wear shows the efficiency of the tungsten carbide tool over the high-speed steel cutting tool, as it can be seen from the results obtained that the lowest tool wear in the turning of the cylindrical steel bar is recorded from the use of the tungsten carbide cutting tool. From the 3D surface plots, it can be confirmed that to obtain a good performance from the different cutting tools, the cutting speed best suited for the cutting tool must be taken into consideration.

Narrow space characteristic is a common structural feature of aircraft assembly, which puts forward higher requirements for the end-effector of a robot drilling system. This paper proposed a new robotic simple and fast drilling system for aircraft automatic assembly. The robot drilling system and control scheme are designed. The end-effector is designed and calculated theoretically. The workflow of the whole system is designed and analyzed. Besides, a new calibration method is proposed for the system calibration includes the calibration of the robot end-effector and the calibration of the robot system relative to the machined parts. Finally, some drilling experiments are designed to verify the effectiveness of the proposed system. The results show that the newly designed robotic drilling system can meet the requirements of aircraft part drilling, such as the drilling accuracy is better than 0.5 mm, the drilling process is more stable, and the rigidity of the system is better. The drilling error of the hole diameter of this system can be controlled below 0.1 mm. The relative distances between holes in the X and Y direction and the hole edge distance meet the technical requirements, and all errors can be controlled to less than 0.5 mm, respectively.

The work presented is concerned with the estimation of manufacturing cost at the concept design stage, when little technical information is readily available. The work focuses on the nose cowl sections of a wide range of engine nacelles built at Bombardier Aerospace Shorts of Belfast. A core methodology is presented that: defines manufacturing cost elements that are prominent; utilises technical parameters that are highly influential in generating those costs; establishes the linkage between these two; and builds the associated cost estimating relations into models. The methodology is readily adapted to deal with both the early and more mature conceptual design phases, which thereby highlights the generic, flexible and fundamental nature of the method. The early concept cost model simplifies cost as a cumulative element that can be estimated using higher level complexity ratings, while the mature concept cost model breaks manufacturing cost down into a number of constituents that are each driven by their own specific drivers. Both methodologies have an average error of less that ten percent when correlated with actual findings, thus achieving an acceptable level of accuracy. By way of validity and application, the research is firmly based on industrial case studies and practice and addresses the integration of design and manufacture through cost. The main contribution of the paper is the cost modelling methodology. The elemental modelling of the cost breakdown structure through materials, part fabrication, assembly and their associated drivers is relevant to the analytical design procedure, as it utilises design definition and complexity that is understood by engineers.

In general, chatter is the main limitation to proper material removal in milling operations. Stability lobes are good tools to determine chatter-free cutting conditions in terms of spindle speed and cutting depth, which require the frequency response function (FRF) at the tool tip to be known. There are experimental methods to measure the tool tip FRF but this may be time consuming or even impossible for each tool and tool holder combination. Receptance coupling substructure analysis (RCSA) is a widely used approach to predict tool tip dynamics. This paper proposes the use of the RCSA approach with a stereolithographic (STL) slicing algorithm to enable the exact calculation of cross sectional properties such as area and area moment of inertia of the cutting tool from its 3D model opposed to the approximation methods. So that, the effect of flutes on cutting tool structure introduced in an exact manner and the RCSA approach becomes feasible for more complicated tool geometries with varying cross-sectional properties, i.e., tapered ball end mills, end mills with variable flute geometries, and so on. The solid model of the tool can be available by either the tool manufacturer or 3D measurement. Although, at the presence of 3D models, finite element methods (FEM) offer accurate simulation of the dynamic response for solid bodies, they suffer from the compromise between accuracy and computation time, as high number of elements is needed for accuracy. Thus, the use of analytical methods where possible improves the simulation time significantly. The proposed STL slicing algorithm is integrated with a previously developed RCSA method. The experimental results show that the proposed algorithm works more accurate in calculation of the cross-sectional properties and hence free-free response of the tool compared to the existing arc approximation methods. It is also shown that the proposed approach performs better than FEM solutions in terms of the computation time and the compromise between accuracy and computation performance. Finally, the proposed approach in prediction of tool tip dynamics for a robotic machining platform.

Based on the development demand of a novel intelligent fixture system, a self-reconfigurable intelligent swarm fixture system is presented. This paper deals with the fixturing layout optimization of a flexible aerospace workpiece. A new fixturing principle, “N-2-1-1,” is put forward. The optimization procedure for fixture layout combined with genetic algorithm and finite element analysis is developed and verified by case study simulation.