Fixture Devices Research Articles

Residual stresses field estimation based on deformation force data using Gaussian Process Latent Variable Model

Residual stresses field inside the bulk material is the main factor of the part deformation, which is a vital issue for large-scaled monolithic components manufacturing in aircraft industry. The estimation of residual stresses is the base of the part deformation control. Non-uniform residual stresses field is distributed among the whole part, and differs from part to part. However, existing residual stress measurement’s methods can only measure the sample’s residual stress and the detection depths are limited by physical principle, which makes it hard to measure the heavy thickness part. In order to address this issue, this paper presents a method of estimating part residual stresses fields and their uncertainty in machining process based on a novel Bayesian statistical model integrated with observation data (deformation force). Deformation forces data can be easily and accurately monitored during machining processing via several fixture devices, and contain information that can be related to the residual stress. In order to solve the problem of how to infer an unobservable residual stresses field by using sparse observed deformation force data, this work introduces a Bayesian framework. The unmeasurable and unobservable residual stresses field is deemed as the latent physics field and the Gaussian process is specified for the latent field as a prior with parameters in kernel function to reduce the solution space and also introduces proper Distribution hypothesis on deformation force data. The model provides an acceptable estimation result with the limited observation data. The proposed method provides an effective way to estimate interior residual stress field in the machining processing of monolithic components part in terms of probability, and will help the selection of deformation control strategy.

Cam – clamping device with variable eccentricity

Productivity and quality growth, all together with cost reductions, are the main objectives of modern manufacturing companies. Fixture devices shall facilitate that the workpiece can be changed fast, to have simple construction, to be cheap and affordable, and they have minimal positioning and installation errors. Clamping forces are applied to the workpiece with the help of fixture devices, after being correctly oriented by the application of adjusting forces. In the stage of design, many parameters are taken into account, like strokes and forces necessary, operation time, build simplicity, all which determines the cost of the device. In the field of device design, the main requirements are related to rapid fixing of the workpiece, fixing of more workpieces simultaneously and reducing the effort of labour for the operators. In this paper is presented the research and construction of a circular cam with variable eccentricity used in one this kind of fixture devices.

Effect of various masked patterned tools during micro-electrochemical texturing

Micromachining technology plays an important role for enhancing the interfacial properties of surface texture by precisely controlling the shape and size of textured surfaces. Maskless micro-electrochemical texturing is a unique method for the generation of surface textures using different masked patterned tools with good shape and size. Fabrication of surface textures depends on suitable masked patterned tools, which are used in maskless micro-electrochemical texturing process. This article presents the effect and capability of six types of masked patterned tools with AZ4903, AZ4620, AZ1415H, synthetic prolite enamel, PMMA (Polymethyl methacrylate) and SU-8 2150 masks for the generation of textured samples utilizing developed experimental setup of maskless micro-electrochemical texturing. AZ4903, AZ4620, AZ1415H, synthetic prolite enamel and SU-8 2150 masked tools are used for fabrication of micro circular patterns and PMMA masked tool is used for varactor micropattern generation using maskless micro-electrochemical texturing. The developed maskless electrochemical micromachining (EMM) setup consists of various sub-systems, namely EMM cell, workpiece and tool fixture devices, electrical connections and vertical cross flow electrolyte circulation systems. The effect of applied voltage, inter electrode gap and flow rate is investigated on textured characteristics i.e. overcut, machining depth and surface roughness(Ra) using six types of masked patterned tools during maskless micro-electrochemical texturing process. From the experimental investigations, it is observed that SU-8 2150 masked patterned tool is most suitable for the generation of surface texture with higher machining accuracy and good surface quality than other masked tools. The achieved best textured characteristics using SU-8 2150 mask are overcut of 21.33 μm, machining depth of 26.36 μm and surface roughness of 0.0672 μm during maskless micro-electrochemical texturing.

Application of Thermal Tool Holder in Mechanical Engineering

Abstract The paper is focused on testing the thermal tool holder during milling operation from the point of view shimmy and roughness machined surface of the equipped tool. Experimental work will include testing of surface roughness parameters of the machined surface structural steel 1.0553 (Fe510C1) in combination with the monolith three-lips cutter Kennametal F3AU177BDK38 from cemented carbide coated with TiAIN PVD coating. Experimental machining will distinguish the climb milling and conventional milling and will be done under predetermined conditions, always at 15 cycles and in relation to other types of fixture devices. All testing will be done at a sufficiently rigid machine CNC FGS 40/50. During machining will be measured and subsequently evaluated power machine during the milling process, shimmy and selected parameters of the roughness of the machined surface.

Mechanical properties and cytocompatibility of oxygen-modified β-type Ti–Cr alloys for spinal fixation devices

In this study, various amounts of oxygen were added to Ti–10Cr (mass%) alloys. It is expected that a large changeable Young’s modulus, caused by a deformation-induced ω-phase transformation, can be achieved in Ti–10Cr–O alloys by the appropriate oxygen addition. This “changeable Young’s modulus” property can satisfy the otherwise conflicting requirements for use in spinal implant rods: high and low moduli are preferred by surgeons and patients, respectively. The influence of oxygen on the microstructures and mechanical properties of the alloys was examined, as well as the bending springback and cytocompatibility of the optimized alloy. Among the Ti–10Cr–O alloys, Ti–10Cr–0.2O (mass%) alloy shows the largest changeable Young’s modulus following cold rolling for a constant reduction ratio. This is the result of two competing factors: increased apparent β-lattice stability and decreased amounts of athermal ω phase, both of which are caused by oxygen addition. The most favorable balance of these factors for the deformation-induced ω-phase transformation occurred at an oxygen concentration of 0.2mass%. Ti–10Cr–0.2O alloy not only exhibits high tensile strength and acceptable elongation, but also possesses a good combination of high bending strength, acceptable bending springback and great cytocompatibility. Therefore, Ti–10Cr–0.2O alloy is a potential material for use in spinal fixture devices.

TU-A-217A-04: Radiographic Tomosynthesis: Clinical Applications and Dose

Digital Tomosynthesis enables efficient acquisition tomographic images of many different anatomies in a standard radiographic exam. With experience gained over five years since the introduction of commercially available radiographic tomosynthesis imaging systems, there is growing understanding of potential clinical applications where tomosynthesis can improve the detection or diagnosis of pathology. Clinical examples will be used to demonstrate the use of tomosynthesis in many different applications: the detection of lung nodules in thoracic imaging, improved detection of subtle orthopedic fractures, diagnosing rheumatoid and osteoarthritis, imaging the facial bones and sinuses, abdominal imaging, and imaging near metal implants and fixture devices. With increasing utilization of this technique, it is important to understand the dose delivered to the patient so that appropriate selections may be made to obtain the necessary diagnostic information with the lowest reasonable dose. Dosimetric techniques for tomosynthesis and comparisons to standard radiography exams and computed tomography will be discussed Learning Objectives: 1. Understand the numerous clinical applications of radiographic tomosynthesis. 2. Understand the factors required in determining the absolute and relative dosimetry of tomosynthesis exams. 3. Understand the relative dose of common tomosynthesis exams compared to standard radiography and computed tomography exams.Author an employee of GE Healthcare.

Development of New Titanium-Molybdenum Alloys with Changeable Young's Modulus for Spinal Fixture Devices

Development of New Titanium-Molybdenum Alloys with Changeable Young's Modulus for Spinal Fixture Devices

OS07F043 Development of new titanium-molybdenum alloys with changeable Young's modulus for spinal fixture devices

Metallic implant rods that are used to design spinal fixtures should have a Young's modulus that is not only sufficiently low to prevent stress shielding for the patient but also sufficiently high to suppress springback for the surgeon. Therefore, there is a need for novel titanium alloys with good biocompatibility and a changeable Young's modulus. Molybdenum is non-toxic, and Ti-Mo alloys possess good biocompatibility. In metastable β-type Ti-Mo alloys, an ω phase can be introduced by deformation at room temperature. This study investigated the effects of deformation-induced phases on the mechanical properties of a metastable β-type Ti-16Mo alloy. The experimental results indicate that the Young's modulus, tensile strength, and Vickers hardness are increased remarkably by cold rolling. The microstructural observation result by transmission electron microscopy (TEM) shows that the deformation-induced ω phase transformation occurs during cold rolling in the Ti-16Mo alloy. Therefore, the increase in Young's modulus of the alloy after cold rolling at room temperature can be attributed to a deformation-induced ω phase.

OS07-2-2 Development of new Ti-Mo alloys with changeable Young's modulus for spinal fixture devices

OS07-2-2 Development of new Ti-Mo alloys with changeable Young's modulus for spinal fixture devices

Aspects of reconfigurable and flexible fixtures

The design and manufacture of fixtures and other dedicated tooling for positioning of workpieces are among the major cost drivers in product industrialization. This has spurred research and commercial interest towards other fixturing solutions like reconfigurable fixtures, with the ability to be changed, or “reconfigured”, to suit different parts and products. When reconfiguring, the product interface not only has to be moved but moved to a desired position and orientation. Several different approaches have been used to move and position these devices, all with their own advantages and disadvantages. This article presents different methods used to position and reconfigure flexible fixture devices using a parallel kinematic device as a case. Discussing the different ways to reconfigure a flexible device, the article aims to arrange the techniques according to their key features.

Application of the Electro-rheological Gel to Fixture Devices for Micro Milling Processes

Application of the Electro-rheological Gel to Fixture Devices for Micro Milling Processes

Development of Fixture Devices for Thin and Compliant Workpieces

Fixturing of thin and compliant workpieces is in many ways technically more demanding than fixturing of stiff workpieces. Nowadays, thin and compliant workpieces, e.g., electrical parts containing semiconductor substrates must be supported with uniform contact force in order to assure high positioning accuracy. In particular, workpiece supporters must suppress workpiece deformation during machining. This study presents new fixture devices that can support thin and compliant workpieces securely and minimize the deformation due to the machining force. A low melting temperature alloy was used in the support structure to fulfill the required functions with simple structure.

Deformation Characteristics of Crashworthy Thin-Walled Steel Tubes Subjected to Bending

The collapse behaviour and crashworthy characteristics of cantilever circular tubes subjected to bending are studied both theoretically and experimentally. Three different fixture devices were used and their effect on failure behaviour of the tube was investigated in detail. A theoretical method, proposed by Hodge, slightly modified, is used to analyse the elastic and elastoplastic phases of bending, while a rigid-perfectly plastic analysis is developed to describe the plastic bending phase. Agreement between experimental and theoretical results was found to be quite good.