Applications In Precision Engineering Research Articles

Laser-induced microtextured stators coupling with flexible rotors for low-voltage driving rotational piezoelectric motors

Traveling-wave ultrasonic motors promise widespread applications in precision engineering, medical, and aerospace field due to their high-power density, but suffer from low efficiency and stress gradient. In this case, the synergy effect of surface-functionalized friction regulation and interface coupling interference of wear loss/debris could effectively eliminate these deficiencies. Herein, we report a low-voltage driving rotational piezoelectric motor (PM30) that proceeds through laser-induced microtextured stators coupling with flexible rotors, which enables working at a rotational speed of 158 rpm and torque of 73 N·mm, respectively, under the condition of low-voltage (80Vp) and low-preload (40 N). Such operation parameters are far beyond the current reported results. Furthermore, FEM simulation and SEM observation demonstrated that the low-voltage driving and high-performance output are resulting from the combination of surface microtextured stators for friction enhancement and flexible rotors for displacement amplification with contact expansion, which regulates tangential friction and reshares the stresses distribution during the dynamic contact along with the rotary motion of rotors. This work provides a promising strategy to construct friction-stress regulation and energy-transformation enhancement toward energy-saving and high-efficient friction drive for piezoelectric devices.

Design and modeling of a piezo-driven three-dimensional bridge-type amplification mechanism with input/output guiding constraint.

Owing to the limited stroke of piezo stacks, compliant amplification mechanisms are widely employed to magnify the displacement of piezoelectric actuators for emerging applications in precision engineering. In this study, a three-dimensional (3D) bridge-type amplification mechanism composed of two serially connected bridge-type amplifiers with a novel constraint form has been developed. The parallel guiding beams mounted at the input and output ends significantly increase the lateral stiffness and minimize parasitic displacements for higher accuracy. Furthermore, a new theoretical model is established to predict the magnification behavior of the 3D amplifier that takes into account the displacement loss caused by the coupling of the two bridge-type amplifiers. The accuracy of this model and the mechanical performance of the developed amplifier are verified by conducting finite element simulations and experimental studies on the manufactured prototypes.

The art of laser ablation in aeroengine: The crown jewel of modern industry

In this perspective, laser interaction with materials and its applications in precision engineering are mainly introduced for the manufacturing, as well as maintenance, repair, and overhaul (MRO) of aeroengines. In precision engineering, the laser ablation tool has also been more applicable considering its great advantages in microprocessing and nanofabrication. It is interesting to explore the specific process and characteristics of laser ablation, which play an important role in advanced manufacturing. Due to the complicated production procedures of an aeroengine, it is important to explore the physics behind laser interaction with aerospace and aeronautical metallic materials in order to properly utilize the unique characteristics of lasers, such as high monochromaticity, high brightness, high directivity, and high coherence. Meanwhile, it is beneficial to study the dynamic process of interactions and its mechanisms in laser applications, such as laser cleaning, texturing, and shock peening. There exist both photo-chemical and photo-thermal processes when lasers and materials interact. Several typical cases are introduced, which have great potential and high impact applications in the manufacturing and MRO industry of aeroengines. Based on laser ablation in specific industries, the building-up of MRO support system for aeroengines could be provided by a dynamic mechanism between the pioneering research results and industrial demand, leading to the fast development of advanced high-end manufacturing equipment.

Laser interaction with materials and its applications in precision engineering

In this paper, laser interaction with materials and its applications in precision engineering are mainly introduced. To further explore the physics behind laser interaction with materials, it is of much significance to investigate the mechanisms in the process. First of all, it is desired to understand the characteristics and principle of laser. Laser is generated by stimulated radiation, and has excellent physical properties, such as high monochromaticity, high brightness, high directivity and high coherence. Meanwhile, it benefits much to study the dynamic process of interactions and its mechanisms. There exist both photo-chemical and photo-thermal processes when laser and materials interact. Furthermore, developing laser application in nanomaterial synthesis is also an unique area. It is worth further studying the design and fabrication of nanostructured materials. Last but not least, it is interesting to explore the specific process and characteristics of laser processing, which play an important role in advanced manufacturing. In precision engineering, the tool of laser has also been more applicable considering its great advantages in microprocessing and nanofabrication. Several case studies are introduced, which have great potential and high impact applications, such as ultrafast laser direct writing, laser micro-lens lithography, laser nanofabrication to break through optical diffraction limit and hybrid micro/nanostructures with unique functions fabricated by laser. These studies have triggered intensive research interests due to their great application prospect.

Fracture toughness of hydroxide catalysis bonds between silicon carbide and Zerodur low thermal expansion glass-ceramic

In many optical and precision engineering applications, low thermal distortion materials need to be bonded together reliably. Since high temperature bonding process ultimately introduce stresses in the bond, rendering it dimensionally instable, room temperature or near room temperature processes are preferred. Low thermal distortion materials such as silicon carbide and low thermal expansion glass ceramics are bonded at room temperature using hydroxide catalysis bonding with a silicate bonding material. The bonding procedure is explained and fracture toughness results are presented for SiC–SiC, Zerodur–Zerodur and SiC–Zerodur bonds. A surface treatment technique for hydrating the SiC surface is presented, which eliminates the need for pre-oxidized SiC surfaces when using HCB bonding. The bonds between surface treated bare SiC surfaces and thermally oxidized SiC surfaces are found to have comparable fracture toughness.

Cancelling bias induced by correlation coefficient interpolation for sub-pixel image registration

Accurate sub-pixel image registration has many applications in precision engineering and manufacturing. Due to its computational efficiency, correlation-based sub-pixel image registration is especially useful for real-time applications. This paper presents a theoretical analysis of the bias induced by correlation coefficient interpolation, when employed to achieve two-dimensional sub-pixel registration resolution. An analytical model of bias in terms of true sub-pixel image shift is first derived according to the given reference image model. It is then used to establish an accurate bias map expressed explicitly in terms of sub-pixel image shift estimated from coefficient interpolation. This bias map is readily employed to eliminate the bias error and to significantly improve measurement accuracy for real-time applications. A bias cancellation scheme was implemented and verified by means of both computer simulation and experimental results. Specifically, sub-nanometre measurement precision was experimentally demonstrated using a microscopic vision system implemented for real-time motion tracking.

PERFORMANCE ANALYSIS OF A LOW-COST TRIANGULATION-BASED 3D CAMERA: MICROSOFT KINECT SYSTEM

Abstract. Recent technological advancements have made active imaging sensors popular for 3D modelling and motion tracking. The 3D coordinates of signalised targets are traditionally estimated by matching conjugate points in overlapping images. Current 3D cameras can acquire point clouds at video frame rates from a single exposure station. In the area of 3D cameras, Microsoft and PrimeSense have collaborated and developed an active 3D camera based on the triangulation principle, known as the Kinect system. This off-the-shelf system costs less than $150 USD and has drawn a lot of attention from the robotics, computer vision, and photogrammetry disciplines. In this paper, the prospect of using the Kinect system for precise engineering applications was evaluated. The geometric quality of the Kinect system as a function of the scene (i.e. variation of depth, ambient light conditions, incidence angle, and object reflectivity) and the sensor (i.e. warm-up time and distance averaging) were analysed quantitatively. This system's potential in human body measurements was tested against a laser scanner and 3D range camera. A new calibration model for simultaneously determining the exterior orientation parameters, interior orientation parameters, boresight angles, leverarm, and object space features parameters was developed and the effectiveness of this calibration approach was explored.

Aero-lap polishing of poly crystalline diamond inserts using Multicon media

Increasing use of poly crystalline diamond (PCD) inserts as cutting tools and wear parts is vividly seen in automobile, aerospace, marine and precision engineering applications. The PCD inserts undergo series of manufacturing processes such as: grinding that forms the required shape and polishing that gives a fine finish. These operations are not straight forward as PCD is extremely resistant to grinding and polishing. Single crystal diamond can easily be polished by choosing a direction of easy abrasion, but polishing a PCD imposes serious difficulties as the grains are randomly oriented. Prior research on polishing of PCD inserts includes electro discharge grinding (EDG), dynamic friction polishing and grinding by a vitrified bonded diamond wheel. The surface textures of PCD produced using an EDG process often contains: micro cavities, particle pullout, micro-grooves, chipped edges, cracks and gouch marks. While applying the dynamic friction polishing method the PCD material undergoes phase transformation and hence increased polishing rate was apparently seen. However the phase transformation of PCD deteriorates the strength of the insert. Furthermore the inserts produced using the dynamic polishing method often exhibits cracks, chip off and edge damage while using as a cutting tool. Therefore, a new method “aero-lap polishing” was attempted as it applies controlled amount of impinging force by which the surface damage can be significantly reduced. The study did establish an improvement of surface finish of PCD from Ra=0.55μm, Rt=4.5μm to Ra=0.29μm, Rt=1.6μm within 15–25min of polishing time along with significant reduction in surface defects.

Modeling and Control Analysis of a 3-PUPU Dual Compliant Parallel Manipulator for Micro Positioning and Active Vibration Isolation

In recent years, many applications in precision engineering require a careful isolation of the instrument from the vibration sources by adopting active vibration isolation system to achieve a very low remaining vibration level, especially for the very low frequency under 10 Hz vibration signals. This paper presents a 3-PUPU dual parallel manipulator for both rough positioning and active vibration isolation in a wide-range workspace based on our previous research experiences in the systematical modeling and study of parallel robots. The manipulator is designed as a kind of macro/micro hybrid robot. Both the kinematics model for macro motion and dynamics model for micro motion are established by using stiffness equation and the Kane’s method, respectively. An active vibration control strategy is described by using the H2 method. Moreover, numerical simulations on the inverse solution for macro motion, workspace, and the active vibration control effects are performed at the end of this paper.

Review Article: Inventory of platforms towards the design of a statically balanced six degrees of freedom compliant precision stage

Abstract. For many applications in precision engineering, a six degrees of freedom (DoF) compliant stage (CS) with zero stiffness is desirable, to deal with problems like backlash, friction, lubrication, and at the same time, reduce the actuation force. To this end, the compliant stage (also known as compliant mechanism) can be statically balanced with a stiffness compensation mechanism, to compensate the energy stored in the compliant parts, resulting in a statically balanced compliant stage (SBCS). Statically balanced compliant stages can be a breakthrough in precision engineering. This paper presents an inventory of platforms suitable for the design of a 6 DoF compliant stage for precision engineering. A literature review on 3–6 DoF compliant stages, static balancing strategies and statically balanced compliant mechanisms (SBCMs) has been performed. A classification from the inventory has been made and followed up by discussion. An obviously superior architecture for a 6 DoF compliant stage was not found. All the 6 DoF stages are either non-statically balanced compliant structures or statically balanced non-compliant structures. The statically balanced non-compliant structures can be transformed into compliant structures using lumped compliance, while all SBCMs had distributed compliance. A 6 DoF SBCS is a great scope for improvements in precision engineering stages.

Multiple reflection Michelson interferometer with picometer resolution

A Michelson interferometer based on an optical set-up allowing multiple reflection between two plane mirrors performs the multiplication of the optical path by a factor N, proportionally increasing the resolution of the measurement. A multiplication factor of almost two orders of magnitude has been demonstrated with a simple set-up. The technique can be applied to any interferometric measurement where the classical interferometer limits due to fringe nonlinearities and quantum noise are an issue. Applications in precision engineering, vibration analysis, nanometrology, and spectroscopy are foreseen.

Design of command shapers for residual vibration suppression in Duffing nonlinear systems

Residual vibrations generated from rest-to-rest maneuvers are crucial for applications in precision engineering, active structural control, space engineering, and other mechatronics applications. In certain applications, the structures to be controlled could be highly nonlinear yet lightly damped. Although the traditional input shaping techniques, which utilize destructive interference, work well for linear and weakly nonlinear systems, they show little effects on systems with strong nonlinearity. In this paper, a general input shaper design methodology for single-degree-of-freedom systems with Duffing nonlinearity is developed by an energy approach. Following this approach, two-step and three-step shapers, as well as their design procedures, are developed, which in the linear limit reduce to the traditional zero-vibration and zero-vibration-and-derivative shapers, respectively. The robustness of these nonlinear shapers is investigated numerically through case studies. The results show that the three-step shapers are sufficiently robust to resist certain level of parameter variations (from their designed values) without exciting significant residual vibrations. The two-step shapers, however, are less robust in comparison. Meanwhile, it is also found that the presence of damping effectively disturbs the energy flow and thus induces residual vibrations. For the less robust two-step shapers, an effective ‘online tuning’ scheme is also proposed here to further improve its performance in a damped nonlinear system. These shaping schemes, as well as their practical adjustment routing, could be applied to the particular structural or mechatronics systems with Duffing or other nonlinearities for vibration suppression to enhance the performance of mechatronics systems.

The Comparison of Solid Silicone Rubber Types Manufactured by Diverse Technologies

The paper presents the current results of our ongoing research on the field of silicon rubber applications in precision engineering and in medical industry. We have demonstrated two technologies for the manufacturing of precision parts and devices for the medical industry. The mechanical properties of the silicone rubber materials manufactured by press vulcanisation and by moulding (diving) are compared.

Linear Grinding of Microbores Using Diamond-Adhered Wire

Use of microbores of size φ = 100 µm or less has become increasingly common for engineering components especially for microfluidics, optical communications and precision engineering applications. These microbores demand nanometric surface finishes to achieve lower insertion loss (<25 dB) for optical applications, ripple-free flow in microfluids and enhanced assembly accuracies in precision engineering. To meet such stringent requirements, microbores are currently produced using microabrasive slurry polishing. Since, this method introduces severe clogging of abrasive particles and requires frequent cleaning, a linear diamond wire grinding method was devised to process microbores up to φ = 80 µm. Prior to microbore polishing, the microbores were formed through a sintering process, and the interacting surfaces were treated as convex–concave which determines the conditions of the contact mechanics. This article explains both theoretical and experimental components of linear diamond wire grinding and outlines the design of a new microbore polishing machine. The process monitoring and signal processing techniques for measuring the cutting forces, wire speed, down feed rate, and wire bow angle in diamond wire linear grinding are also discussed.

State-of-the-art of non-destructive measurement of sub-surface material properties and damages

The possibilities of common non-destructive measuring techniques are reviewed in this paper for their applications in precision engineering. The grazing X-ray technique is believed to be a powerful improvement of the conventional X-ray techniques under both the diffraction mode and the fluorescent mode. Information of the crystallographic structure and chemical composition can be obtained to a nanometre resolution. Ultrasound can be used in scanning acoustic microscopy to give information on the physical or even chemical nature of superficial layers. Raman spectroscopy has now become an important tool for studying superficial structures, chemical composition and stresses in cyrstalline and amorphous materials: it is recommended to use this method especially for the investigation of monocrystalline silicon and germanium. The instrumented microindentation technique is a quasi- non-destructive technique for evaluating mechanical material properties like hardness and Young's modulus in a nanometre range. It can be used on any material that does not require special surroundings like a vacuum. Photothermal microscopy has been developed recently for the non-destructive testing of the local thermal properties of materials. By using the Mirage effect and its local measurement above the surface, a non-destructive depth profiling of surface damages can be obtained.

Constant-Velocity Shaft Couplings: A General Theory

The theory here expounded reveals certain inescapable geometrical conditions with which all couplings must comply when they are required to reproduce at the output shaft, simultaneously and precisely, all angular input shaft displacements. Plunging-type linkage couplings, whose geometrical forms follow very simply from the theory, are fully listed for both intersecting and parallel shafts. Many, particularly those for parallel shafts, are entirely new, and it is believed that there could be useful precision-engineering applications.