The dual-driving feed worktable (DDFW) is widely used in feed system because of its high stability and load capacity, while its feed system is one of the important parts that affects the feed accuracy of machine tools. Due to the influence of assembly, manufacturing and other factors, the positioning error of DDFW is produced, which reduces the machining accuracy of the machine tools. Therefore, the research on the positioning error compensation of DDFW is of great significance. In this paper, the positioning error of DDFW is measured with absolute optical scale and the positioning error model of DDFW is established by modeling method of orthogonal polynomials at first. Then an electronic cam combined with virtual axis compensation strategy is designed for DDFW to reduce positioning error. Finally, the compensation experiment is carried out and the error compensation results are analyzed to verify the effectiveness of the error compensation strategy designed in this paper.

When the body, main support and other large metal parts are damaged, welding or surfacing is generally used as the repair method. Measuring volume of repair is a key step before welding repair, because former provides relevant parameters for latter. Line structured light detection is a fast and convenient machine vision detection method, which is suitable for detection tasks in various complex environments and satisfies the requirements of volume of repair of engineering equipment detection. This paper designs a scheme based on line structured light. In this scheme, the parameters of welding repair are obtained by several steps, such as scanning, image processing, light strip center extraction and trend points extraction. Compared with other common methods, this scheme has the advantages of fast detection, easy operation, high cost-performance ratio and easy expansion. especially in combination with welding robots, it can greatly improve the level of automation and reduce the maintenance time.

The rotor stand vibration signals carry abundant dynamic information of the machinery and are sometimes very useful in the machinery fault diagnosis. Due to the difficulty of recognition for the non-stationery signals, many traditional ways have been discussed and made the comparison to analyze the pros and cons of the methods. Then this paper proposed an improved LMD time-frequency method to solve the shortcuts, so as to obtain the better results during the machinery fault diagnosis. The LMD time-frequency method helps to reduce the appearance of the singular points and glitches and it has better precision in the PF component, so that the characteristics of the original signal can fully be reflected. And the simulated rotor signal along with actual fault signals are used to demonstrate, test, verify the accuracy and the effectiveness of the improved LMD method with the support of the established test rig and NI device. Through the Time-Frequency Analysis Time Spectrum, the newly proposed method has been proved its accuracy, efficiency in the time-frequency analysis and its stableness in the machinery fault diagnosis.

Tight interference fits are extensively applied in machine tool and industry, as it can provide stable bearing capacity in an efficient way. However, in most of proposed models for investigating the load bearing characteristics of interference fits, it is not common to consider roughness and form defects together. It is limited to describe interference fits of simple parts and investigate the effects of form defects approximately. The objective of this study is to present a feasible method to investigate the effects of form defects on the load bearing characteristics of interference fits of shaft and bush. The analytical method is established based on thick-walled cylinder theory and the experimental data on the joint surface. It takes both roughness and form defects into account, and predicts the load bearing characteristics under different parameters of form defects, such as the period and amplitude. The results show that the distribution of contact pressure of joint surface depends on the different parameters of form defects. Furthermore, as the amplitude of form defects decreases, the effects on bearing capacity of interference fits also decrease gradually.

Motor shaft is one of the most important parts of motor, which is widely used in industrial field. The straightness of the shaft has a potentially significant effect on motor performance, which is determined by the straightening process in the manufacturing process of the shaft. Considering the grooved characteristics on the micro-motor shaft and using the classical material mechanics principle, the stress and deformation models of the circular shaft with the grooves during the straightening process are established in this paper. By deriving the straighttening stroke-initial deflection model, an accurate and practical relationship between the straightening stroke and the initial deflection was provided. In order to verify the theoretical straightening model, some grooved shaft specimens are designed and manufactured for the straightening experiments. Through the simulation and experimental research, the straightening stroke-initial deflection model for the micro-motor shaft is compared and analyzed, and the correctness and feasibility of the model is verified.

Straight metal pipes are widely used in petroleum exploration and transmission equipment systems. Straightening is one of effective methods for ensuring or repairing the bending during straight metal pipe rolling, heat treatment, assembly and operational application. However, the flatten phenomenon of straight metal pipe during straightening process is unavoidable. Therefore, it is significant to study the flatten phenomenon of straight metal pipe in straightening process. Based on the theory of elastoplastic deformation, the flatten phenomenon of straight metal pipe is analyzed. Further, the straightening stroke model of straight metal pipe for guiding the straighten operation is established. Afterwards, the theoretical straightening stroke model is analyzed on the basis of simulation. Finally, the experimental system was built up. A series of related experiments were carried out to verify the rationality of the model.

To improve the compressive capacity and straightening efficiency of straightening process, the stroke-deflection model (SDM) using dual indenter and dual clamp system (DIDCS) for linear guide rails is developed in this paper. The DIDCS is actually simplified as a symmetrically supported beam with two symmetrical concentrated forces on the top surface of workpiece, so the straightening process is regarded as pure bending process. To explore the deflection variation during the whole process with DIDCS, the curvature-deflection model (CDM) considering the span control of dual indenter and dual clamp is firstly analyzed based on elastic-plastic deformation theory and small deformation principle. The geometrical features and material properties of linear guide rails, which are the main factors influencing bending characteristics, are then mathematically modeled for the further analysis of stress and strain distributions in straightening process. Besides, to obtain the actual bending moment model (BMM) of different model parameters, the distribution regulations of elastic and plastic regions are analyzed followed by pure bending assumptions. The bending rebound model (BRM) is established with bending moment, geometrical features and material properties, and the SDM is finally calculated by initial deflection, rebound deflection and span parameters of the DIDCS. On basis of the DIDCS, the straightening process is simulated with the established finite element analysis model (FEM) to demonstrate the longitudinal stress distribution and the reflection of different straightening stages. The proposed SDM is also experimentally validated on the ROSE-JZ50 straightening machine with different materials.

Given the chord length of equal angle isn’t equal on elliptical section of piston skirt with middle-bulged varying ellipse (PSMVE), a larger theoretical processing error will inevitably be introduced with the interpolation algorithm of equal angle for PSMVE. To improve the manufacturing precision of PSMVE, a novel interpolation algorithm of equal-length-chord and spiral-line (IAES) and a method of tool radius compensation are presented based on symbolic computation. Firstly, a three-dimensional model of PSMVE is generated through the symbolic computation method, meanwhile, the coordinate values of arbitrary cutter-contact point can be expressed accurately. Secondly, the turning spiral trajectory is generated via updated cutter-contact point which can be searched from the obtained cutter-contact point with equal length chord. Besides, this paper proposes a method of tool radius compensation and obtains the cutter location points through appropriate transformation of coordinates. Last, some simulation, which mainly includes the establishment of 3D model, the generation of spiral trajectory with equal-length-chord, the transformation between cutter-contact point and cutter-location points, is carried out. In addition, this paper takes CNC turning center (System: SINUMERIK 802C) as an example to complete the processing of PSMVE. Experiment results verify that the machining method is appropriate for PSMVE.

Straightening processing is one of the most important processes to improve straightness of linear motion components. The most urgent problem to be solved by the precision straightening process is the residual deflection caused by elastic rebound and obtaining accurate straightening stroke. Stroke-deflection model is a major critical factor that decides the precision and efficiency of straightening process. In this paper, a novel way to establish and simulate the stroke-deflection model is proposed based on mathematical method, bending experiment and online real-time measurement method. The online real-time technology, as well as online measurement experiment and data processing, improves the accuracy of stroke-deflection model. It is demonstrated that the stroke-deflection model adjusted by the online measurement model is more accurate than that of the theory model and bending experiment model. The stroke-deflection model based on online measurement can compensate the errors caused by various reasons and be more compatible with the actual straightening process.

The pipeline risk assessment has been part of the integrity management in the industry in today’s environment of increasing regulatory and public oversight. One of the widely used risk assessment method is the score index method. This method has been used for more than two decades and is widely accepted in the pipeline industry. The input data is relatively easy to acquire. The method provides details of mitigation options and relative risk values. However, this method does not provide the simple decision making process. In risk management, it is always the question to choose the most cost effective mitigation option to use limited resources. On the basis of score index risk assessment method, a method to correlate the probability of failure score with actual failure probability, and leak impact factor score with actual failure consequence in monetary units has been developed. This method applies the monetarily calibrated consequence factor to the probability of failure to obtain a normalized and calibrated risk in monetary unit. By comparing the cost of an estimated mitigation program, the decision can be made. Recent regulations in Canada require that risk assessment must have a method to determine the significant risk threshold. Even though some industrial standards have some recommended methods or benchmark data for failure probability, there is no published method to determine the threshold of high risk. Some pipeline companies have the in-house personnel to develop an advanced method to meet regulation requirement. However, many pipeline companies need to have a practical and economical method to determine the significant risk threshold to meet regulation requirement, and to effectively allocate resources. This paper develops a method to determine the significant risk threshold that can be used as a decision-making criterion in pipeline risk management. This process is practical for industrial application, especially for upstream companies where operators have limited resources for advanced risk assessment. A case study is presented using this method based on upstream pipelines.

The pipeline risk assessment has been more and more widely used in the industry because of economic factors and regulatory requirements. The three most popular risk assessment methods are qualitative method (simple decision making matrix method), semi-quantitative method (score index method) and quantitative method. The decision-making matrix method greatly depends on expert’s opinion, and does not provide much information to optimize the mitigation program. The quantitative method provides details of mitigation options, mitigation criteria, and prioritizations, but requires a lot of input data that the pipeline operators usually do not have. The score index risk assessment is widely used in the pipeline industry. The input data is relatively easy to acquire. The method provides details of mitigation options and relative risk values. The score index risk assessment is a relative method. Upstream pipeline operators often have questions, such as “Which is the most effective mitigation option to use with my limited resources?” and how the index scores relate with the actual failure frequencies and failure consequence. In order to effectively answer these questions, this paper outlines a method to correlate the probability of failure score with actual failure probability, and leak impact factor score with actual failure consequence in monetary units. Rather than using the final risk score, this method applies the monetarily calibrated consequence factor to the probability of failure so that a normalized and calibrated risk in monetary unit is obtained. By comparing the cost of an estimated mitigation program, the decision can be made based on relative risk. This process is straightforward and practical for industrial application, especially for upstream companies where operators have limited resources to run an in-depth risk assessment. A case study is presented using this method based on upstream pipelines.

Semiconductor alloys with epitaxially embedded nanoparticles have been shown to be very promising materials for thermoelectric energy conversion applications. In this work, we report on thermal conductivity characterization of two classes of p-type nanoparticle-in-alloy composite materials: compensated InGaAs semiconductor matrix with randomly distributed ErAs nanoparticles, and GaSb and its alloys with embedded ErSb nanoparticles. The three omega method is used to measure thermal conductivity of all materials. It is shown that thermal conductivity of compensated p-type ErAs:InGaAs is comparable to the n-type ErAs:InGaAs and it reduces with the increase in the erbium concentration. ErSb:GaSb nanocomposites are intrinsically p-type and show a thermal conductivity substantially lower than the pure GaSb compound. By comparing nanostructured samples from alloyed (InGaSb) and unalloyed (GaSb) matrix materials, we show that alloying is complimentary to the role of the nanostructure in reducing thermal conductivity. We also discuss Boltzmann transport modeling that indicates an optimum nanocrystal size, and the prospects for further reductions in the lattice thermal conductivity.

The performance of older ERW pipelines has raised concerns regarding their ability to reliably transport product to market. Low toughness or “dirty” steels combined with time dependent threats such as surface breaking defects, selective corrosion and hook cracks are especially of concern in hazardous liquid pipelines that are inevitably subject to cyclic loading, increasing both the probability and rate of crack growth. The existing methods of evaluating seam weld flaws by hydrostatically testing the pipeline or In-Line Inspection (ILI) with an appropriate technology are well established. Hydrostatic testing, whilst providing a quantified level of safety is often impracticable due to associated costs, logistics and the possibility of multiple failures during the test. ILI technologies have become more sophisticated and as a result can accurately detect and size both critical and sub-critical flaws within the pipeline. However, the vast amounts of data generated can often be daunting for a pipeline operator especially when tool tolerances and future growth are required to be accounted for. For either method, extensive knowledge of the benefits and disadvantages are required to assess which is the more appropriate for a particular pipeline segment. This paper will describe advances in the interpretation of seam weld flaws detected by ILI and how they can be applied to an Integrity Management Plan. Signal processing improvements, validated by in-field verifications have enabled detailed profiles of surface breaking defects at seam welds for ERW pipelines to be determined. Using these profiles along with established fracture and fatigue analysis methods allows for reductions in the unnecessary conservatism previously associated with the assessment of seam weld flaws detected by ILI. Combining these results with other available data, e.g. dig verifications, previous hydrostatic testing records, enables more realistic and better-informed integrity and maintenance planning decisions to be made. A real case study conducted in association with a pipeline operator is detailed in the paper and quantifies the benefits that can be realised by using these advanced assessment techniques, to safely and economically manage their assets going forward.