Cirp Annals-Manufacturing Technology最新文献

The accuracy of touch-trigger probing by a six-axis robotic manipulator is determined by the accuracy of the robot forward kinematic model to estimate the stylus sphere position from angular positions of rotary axes. Many conventional studies have employed the Denavit–Hartenberg (DH) model, containing position and orientation errors of the rotary axis average lines as error sources. This paper proposes the application of a new kinematic model, containing the angular positioning deviations of all the rotary axes, to the robotic probing. The probing accuracy is experimentally investigated in profile probing of a straightedge over the robot's workspace.

Titanium alloys are an important material for several industries, despite being very energy intensive to produce. This study aims to maximize chip recyclability by adjusting the milling process and subsequent processing steps. The results show that the chip morphology determines the recyclability significantly. Also, a cleaning process is established to reduce chemical contamination. Based on the results a closed-loop material cycle for Ti–6Al–4V powder for additive manufacturing is presented. It is shown that the powder and material properties of printed samples are similar to those of conventional materials, while energy savings of up 77 % can be achieved.

Metal additive using Powder Sheets is an innovative technology driven on eliminating loose powder in laser based additive manufacturing. The utilisation of a novel composite polymer-powder material enables the complete encapsulation of powder to mitigate safety risks and production issues associated with loose powder. This research demonstrates the versatility of this technology through varying the composition of the novel composite material, to deliver stronger, harder and more ductile materials. It is demonstrated that high-entropy-alloys can be printed with better mechanical properties while not altering the solid solution. Future applications arise in the field of multi-materials and coatings.

This work investigates the combination of wire electrical discharge machining (Wire EDM) and wire electrochemical machining (Wire ECM) in a single medium to obtain good surface quality and dimensional accuracy without sacrificing productivity. The experimental setup is evaluated with respect to the deviations in the profile accuracy and surface roughness. The developed strategy is validated and findings suggest that Wire ECM requires an accurate starting contour, obtained by first preparing the surface using Wire EDM. Results indicate the feasibility of the hybrid platform, combining the good accuracy (5 µm) and good surface finish (< 0.5 µm Ra) of either process.

Forming processes are known for their intricacies in prediction and control due to the complex loading conditions and material flow. This paper will first introduce the AI algorithms used or having potential to be used in forming, and then investigate the state-of-the-art advances of AI-based technologies in forming processes with four main pillars of process simulation, process design and optimization, in-situ process control, and qualification and certification of forming processes and formed products. Future directions of AI in forming for both academic research and industrial applications will be proposed to leverage digitalization and data science to explore new solutions in forming processes.

A clear definition of the measurand is an essential precondition for measuring. When verifying conformity to ISO GPS tolerances (verification), the measurand is often unclear, particularly for geometrical tolerances. The tolerance zone is a portion of space whereas the measurand is a scalar quantity, and many such quantities may be derived from the same portion of space. We propose a unified derivation of the measurand in ISO GPS verification matching the designer's intent. Different types of tolerances are considered, from the easiest to the least obvious as to the derivation of the measurand.

An investigation is made into traverse diamond dressing of grinding wheels using radiused dressers. Previous methods have modeled dressing using an equivalent diamond-contact width. This method contains inherent problems, particularly with overlap ratio and dressing depth. In this study, the geometry is modeled as a series of scallops. Dressing sharpness is quantified using the concept of Aggressiveness, which unifies numerous disparate parameters into a single dimensionless parameter. Experiments show that this single parameter accurately quantifies dressing sharpness for radiused, rotary, traverse-disc dressing. Also, the concepts of minimum achievable specific energy and the transient nature of wheel sharpness are investigated.

Microstructures with high surface integrity are difficult to efficiently fabricate on silicon carbide. A method for modifying the band gap via ion implantation is proposed, which induces a crystalline-to-amorphous transition so that the laser intensity for material removal is substantially reduced. The structure can be generated by a single pulse, considerably increasing the efficiency. Furthermore, chemical etching is introduced to make the process material selective and self-limited. This new approach achieves not only subnanometric roughness but also less subsurface damage and a remarkable improvement in controllability.

Duplex stainless steels (DSS) are defined by their equal phase composition of ferrite and austenite. However, the in-situ formation of this duplex microstructure in laser-based additive manufacturing (AM) is still a challenging topic. Nanoparticle addition is a promising approach to tailor the microstructure of steels in AM. Therefore, DSS doped with 0.5 wt.-% NiO nanoparticles was fabricated by laser-based powder bed fusion (PBF-LB) and directed energy deposition (DED-LB). While having no impact on the phase composition in PBF-LB, the addition of NiO nanoparticles showed a significant increase in austenite content of 9% compared to the unmodified powder in DED-LB.

In this paper, a novel thin-wall milling strategy named “L-stock method” is proposed. The demand of thin walls has continued its increase due to the strict goal setting of reducing carbon emission. However, its practical machining method has not changed for a long time even though many measures were proposed in the literature. In the proposed method, the directional relationships between the cutting process and the compliant direction are focused, and plunge milling is applied aggressively, which leaves an “L”-shaped stock material, to increase the workpiece stiffness. The synergetic advantages of the proposed method are verified mainly by experiments.