Assembly Work Research Articles

Regulation of tolerances of associated parts of mechanisms of livestock farms during repair

The paper considers an algorithm for optimizing the efficient distribution of resources that determine the cost of assembly work, subject to restrictions that ensure high quality assembly of livestock machines and equipment. To determine the required tolerance values for parts, one can use the known methods of parametric optimization. Therefore, the application to the solution of the problem of the method of Lagrangian multipliers as a result of the calculations obtained the optimal tolerances of the details of the angle. Upon completion of the calculations, the optimal assembly parameters of the node for various values are obtained; the result is presented in graphical form. There are various methods for calculating component tolerances of mating parts. Methods based on the statistical evaluation of tolerances and finding their root-mean-square deviations make it possible to reduce the degree of risk when expanding the tolerance limits for mating parts and reduce assembly losses. The correct assignment of tolerances allows one to achieve significant savings in material resources and reduce production costs. The most effective solutions may be those obtained by implementing optimization procedures that ensure the minimization of the quality criterion under the conditions of restrictions determined by the components of the assembly assembly process.

SOLIDWORKS AS AN INNOVATIVE MEANS OF RESEARCHING AUTOMOTIVE ENGINEERING

The main directions of improving the reliability of automotive equipment during repair include the performance of disassembly and assembly work without damage to parts. And for this you need to use lifters, stands, pullers, racks and other devices and means of mechanization. Therefore, the possibilities of designing devices for automobile transport with the help of SolidWorks are considered: a crane lifting mechanism, a stand for straightening deformed stamped wheels of passenger cars, bearing removers, a device for compressing the springs of the front suspension of passenger cars, a device for mounting and dismounting brake drums, a two-post electrohydraulic lifter.

Development of Information System for Evaluation of Work and Prediction of Countermeasures for Problems in Assembly Work

In this study, we develop an information system to evaluate work and predict countermeasures for resolving problems to continuously promote the work process and design in parts assembly work. The information system is constructed using a subsystem including image processing to detect the locations of the tips and joints of the fingers of a worker’s hands and the locations of parts. To predict the problems and generate countermeasures to resolve the challenges, three types of data structures are constructed and they are connected related to works, evaluation values, the causes of the problems, and the countermeasures for problems in the works. We explain the characteristics of the developed system and perform the system in the actual assembly process to evaluate the system’s effectiveness.

WHY ARE EPOXY-COATED STEEL REBARS PROHIBITED IN BRIDGE STRUCTURES IN SOME REGIONS?

One of the common ways in many countries to protect steel reinforcement from corrosion in reinforced concrete structures is to cover its surface with a thin layer of epoxy resin. However, in practice, in many cases, the anti-corrosion effect of epoxy coating was not significant, and the durability of reinforced con-crete bridge structures was lower than those where steel reinforcement was not coated with epoxy resin. Ex-perts believe that one of the factors that affects the corrosion resistance of steel reinforcement with epoxy coat-ing in reinforced concrete is the presence of mechanical damage in the epoxy coating of the reinforcing rod, through which moisture can penetrate. Therefore, in some countries, instructions have been developed for the prevention of such damage at the stages of applying an epoxy coating to the armature, its storage, transporta-tion, and construction and assembly work in the manufacture of reinforced concrete structures. This article discusses the thermomechanical mechanism of violation of the internal structural integrity of concrete rein-forced with steel rods with an epoxy coating, which is caused by a high value of its coefficient of linear thermal expansion and the epoxy coating itself. Using the methods of the theory of thermoelasticity, a mathematical model of this phenomenon was developed, a system of solving differential equations was formed, and its solu-tion was constructed. It was established that even with relatively minor temperature changes in the concrete environment in the area of its contact with the reinforcement, cracks and damages occur along the entire length of the steel reinforcement. All this contributes to further destructive processes and reducing the durabil-ity of reinforced concrete bridge structures.

A posture alignment-based methodology for gap optimization of aircraft composite panel assembly

The widespread use of composite materials in the aviation industry result in the control of the assembly gaps between components a key topic. In this work, a gap optimization method based on component posture alignment is presented to assist in the intelligent assembly of aircraft composite panels. To quantify the assembly gap, a static and posture-dependent dynamic model is developed with the idea of discretization, and then a mathematical evaluation method for the assembly quality is proposed based on two new concepts: gap distribution coefficient and gap distribution factor. Moreover, with a multi-objective optimization method, the assembly gap is minimized and the gap distribution is optimized under the constraints of DOF and assembly tolerances, which provides new ideas for intelligent assembly of big composite panels. Finally, the proposed method is studied by numerical simulations of an assembly work in point cloud, as well as hardware experiments of a composite panel assembly work. These studies, taken together, demonstrate the effectiveness of the proposed method.

Occupational Accident Risk Analysis using Failure Mode and Analysis Method: A Case Study of X City Main Market Development Project

Construction Projects are a work sector that has a high level of work accident risk. This is due to the lack of awareness of the importance of implementing a good Construction Safety Management System (SMKK) following applicable laws and regulations, often the application of the Construction Safety Management System on a project is considered only as a costly expense, not as an investment to prevent work accidents but only is considered to provide a level of loss from the project itself. But, in the construction of the Main Market of City X, there was a work accident; an analysis was carried out using the Failure Mode And analysis method, several works with a high-risk level, namely formwork demolition work, installation work and WF steel assembly work with each value of 48 risk priority numbers with a risk map value of 19, ceiling frame assembly work with a value of 36 risk priority number with a risk map value of 17, Pile head bore work, ceiling material transportation work from storage, test commissioning work with each value of 32 risk priority numbers with a risk map value of 19.

A verification-oriented and part-focused assembly monitoring system based on multi-layered digital twin

In line with the human centricity characteristics of the emerging Industry 5.0 paradigm, manual assembly has long been an indispensable element of the small-batch and customized products. Nevertheless, the flexibility of manual operations is prone to assembly errors caused by human uncertainties. Since the newly assembled part directly determines the quality of products, the part-focused verification method has been widely adopted for manual assembly assistance. However, a part is partial to the whole assembly and occluded by other parts, which makes verification difficult. By leveraging the digital twin (DT) technology, one can construct a physical twin (PT) scene to represent the on-site assembly and a DT scene to represent the assembly’s theoretical status in real time. Only if the part is assembled correctly, the newly assembled part can be mapped to the corresponding DT part model. Otherwise, the difference between the PT and the DT part can indicate a potential assembly error. Based on this idea, this paper proposes a verification-oriented and part-focused monitoring system based on multi-layered digital twin for manual assembly assistance. A multi-layered DT framework is constructed to build the geometric and logical connection between the physical and digital space. With the synchronization of DT, the newly assembled part and its corresponding template are generated using a point cloud reservation algorithm, and a two-direction matching algorithm is adapted to evaluate whether the newly assembled part is in the expected position for verification. The proposed monitoring system only requires one shot of the assembly scene in movable view for verification, which meets the flexible requirement for manual assistance in human-centric assembly. The experimental result shows that the proposed monitoring system can detect potential part errors and track assembly process information after manual assembly work, which is significant for human-centric intelligent manufacturing system development.

Reliability Design of Two-Stage Planetary Gear Wheel Hub Reducer based on Multi-Objective Optimization

The mining dump truck has a large load capacity, low running speed, and the characteristics of low speed and high torque. The planetary wheel reducer can meet this demand, which is widely used in such vehicles. According to the structural characteristics of a 170-ton vehicle two-stage planetary gear reducer, the reliability of planetary gear transmission at all levels was analysed, and the system parameters were optimized on this basis. The multi-objective optimization design method was used to transform the maximum reliability of the system into the maximum reliability of the gears at all levels, and the constraints are established based on the actual processing, operation, installation, assembly and other working conditions. The MATLAB multi-objective optimization module was used to solve the analysis, and the best gear design parameters were obtained after rounding. Under different operating conditions, the planetary reducer before and after optimization was compared and analysed to obtain the reliability and service life of the entire deceleration system after optimization. The analysis results show that: after the parameter optimization of the planetary reducer, the transmission efficiency is 0.946, and the transmission ratio of the system is 30.54, which meets the actual use requirements. The reliability coefficient of the contact strength of the tooth surface of the secondary sun gear is 2.52, the reliability coefficient of the bending fatigue strength of the root of the secondary inner ring gear is 2.59, and the reliability of the secondary gear is 0.989. The reliability is obviously improved. The safety factor of the main parts is high. The service life of each gear of the whole secondary reduction system meets the design requirements. The analysis content and results provide reference for the optimization design and reliability analysis of similar planetary gear systems.

Construction Work Efficiency Analysis—Application of Probabilistic Approach and Machine Learning for Formworks Assembly

Analyses of efficiency are vital for planning and monitoring the duration and costs of construction works, as well as the entire construction project. This paper introduces a combined quantitative (probabilistic) and qualitative (machine learning-based) approach to the problem. The proposed approach covers probabilistic analysis based on fitting a triangular distribution to empirical data, followed by the application of support vector machines (SVM). Following the theoretical assumptions, the paper also presents an application of the proposed approach for formwork assembly as an exemplary construction work. This is based on real-life data, including conditions, characteristics, and features of formwork assembly work recorded on a construction site. As a result of the study, triangular distributions were fitted to data representing efficiencies of formwork assembly for three different types of structural members made of reinforced concrete. The parameters (a—minimum, m—peak and b—maximum values of efficiency measured as square meters of an assembled formwork per hour) of the fitted distributions for the particular real-life data were as follows: for columns a = 0.100, m = 1.450, b = 1.900, for walls a = 0.700, m = 1.995, b = 3.300 and for slabs a = 0.200, m = 2.125, b = 3.200. The obtained distributions allow us to assess the probability of achieving efficiency not less than a certain assumed critical value. The study also developed two SVM models—the first based on so-called C-classification and the second based on ν-classification—capable of recognising with satisfactory accuracy whether the efficiency of formworks assembly works for certain conditions, characteristics, and features of works are above or below median values computed based on previously fitted distributions. The performance of both developed models in terms of proper classification, either for training or testing, was above 80%.

Subassembly Partition of Hull Block Based on Two-Dimensional PSO Algorithm

Subassembly partition is an important process in hull block building as it greatly affects the efficiency and quality of the assembly work. Recently, an experience-based method has been widely applied to the subassembly partition process, which consumes much design time and manpower, thus causing more challenges toward a more highly automated and efficient stage in this process. To shorten the gap, an automated subassembly partition method is presented in this study. First, the assembly information model is defined with essential attributes and topological relations of the parts. Second, an optimization model is established with consideration of a trade-off between the intra-cluster cohesion and cluster number on the premise of satisfying certain constraints. After that, considering the fuzziness and diversity of the subassembly partition problem, a two-dimensional coding discrete particle swarm optimization (PSO) algorithm is developed. Finally, two blocks are demonstrated as instances to verify the proposed method, and the results show that the proposed method is feasible and applicable to the block with a flat structure.

Unraveling the mechanism of [4Fe-4S] cluster assembly on the N-terminal cluster binding site of NUBP1.

[4Fe-4S]2+ cluster assembly in human cytosol requires both a [2Fe-2S] cluster chaperone being able to donate two [2Fe-2S]2+ clusters and an electron donor providing two electrons to reductively couple the two [2Fe-2S]2+ clusters into a [4Fe-4S]2+ cluster. The mechanism through which the cytosolic [4Fe-4S]2+ cluster assembly works is still not defined. Here, we show that a hetero-tetrameric complex formed by two molecules of cluster-reduced [2Fe-2S]+ 2 -anamorsin and one molecule of dimeric cluster-oxidized [2Fe-2S]2+ 2 -GLRX32 orchestrates the assembly of a [4Fe-4S]2+ cluster on the N-terminal cluster binding site of the cytosolic protein NUBP1. We demonstrate that the hetero-tetrameric complex is able to synergically provide two [2Fe-2S]2+ clusters from GLRX3 and two electrons from anamorsin for the assembly of the [4Fe-4S]2+ cluster on the N-terminal cluster binding site of NUBP1. We also showed that only one of the two [2Fe-2S] clusters bound to anamorsin, i.e. that bound to the CX8 CX2 CXC motif, provides the electrons required to form the [4Fe-4S]2+ cluster. Our study contributes to the molecular understanding of the mechanism of [4Fe-4S] proteins biogenesis in the cytosol. This article is protected by copyright. All rights reserved.

Features of designing building general plans

The construction master plan (contgenplan) is the general plan of the construction site, which shows all existing and planned permanent buildings and structures, as well as temporary buildings necessary for construction and assembly works. The purpose of the budget plan is to organize the construction industry on the site, which would ensure the creation of the necessary production and living conditions for workers, the reception and delivery of materials, semi-finished products and structures to the workplace, the normal operation of construction machines and mechanized installations, uninterrupted supply of water and energy resources. There are two types of construction master plan: general site and object.
 The general site budget plan is drawn up during the development of the construction organization project and covers the entire territory of the urban residential massif (microdistrict, block) or cultural and household complex. The facility budget plan is part of the construction project and covers the territory related to one facility or, in some cases, to several. At the stage of the construction project, an object budget plan is developed, which specifies and details the decisions of the site-wide budget plan. The budgenplan should show: entrances and exits, unloading points, entry into dangerous areas, the construction of roads and sidewalks, their width and connection to the designed buildings.
 The budget plan should show storage facilities, temporary buildings, the organization of communication lighting and dispatching of the construction site, the organization of providing the facility with electricity, water, steam, compressed air, and oxygen. Before placing mechanized equipment on the construction site, it is necessary to determine the types and number of cranes, stationary lifts, as well as their installation locations. After that, it is necessary to calculate the operating zones of the cranes, taking into account the specifics of architectural and structural solutions and the construction conditions of the facility.

Design of High-strength Material Non-dismantling Docking Assembly

The construction technology of tower erection by segments with the cranes on the basis of the docking assembly has been applied in multiple cities and provinces in China. The docking assembly reduces the number of hoisting times, and lowers the safety hazards. However, the docking assembly which is an independent structure and made of common materials currently needs to be installed on and dismantled from the tower for each use, and each component is heavy. To address the above problems, the high-strength material non-dismantling docking assembly is studied to develop a design scheme which reduces the weight and eliminates the installation and dismantling work of docking assembly. Its successful engineering application shows that the use of high-strength materials effectively reduces the weight of the docking assembly and the docking assembly developed is safe and reliable, which greatly improves the efficiency of tower erection and reduces labor intensity. The project study results provide a reference for the design of high-strength material non-dismantling docking assembly for other types of transmission towers in the construction of power grids.

NtLink: A Toolkit for De Novo Genome Assembly Scaffolding and Mapping Using Long Reads.

With the increasing affordability and accessibility of genome sequencing data, de novo genome assembly is an important first step to a wide variety of downstream studies and analyses. Therefore, bioinformatics tools that enable the generation of high-quality genome assemblies in a computationally efficient manner are essential. Recent developments in long-read sequencing technologies have greatly benefited genome assembly work, including scaffolding, by providing long-range evidence that can aid in resolving the challenging repetitive regions of complex genomes. ntLink is a flexible and resource-efficient genome scaffolding tool that utilizes long-read sequencing data to improve upon draft genome assemblies built from any sequencing technologies, including the same long reads. Instead of using read alignments to identify candidate joins, ntLink utilizes minimizer-based mappings to infer how input sequences should be ordered and oriented into scaffolds. Recent improvements to ntLink have added important features such as overlap detection, gap-filling, and in-code scaffolding iterations. Here, we present three basic protocols demonstrating how to use each of these new features to yield highly contiguous genome assemblies, while still maintaining ntLink's proven computational efficiency. Further, as we illustrate in the alternate protocols, the lightweight minimizer-based mappings that enable ntLink scaffolding can also be utilized for other downstream applications, such as misassembly detection. With its modularity and multiple modes of execution, ntLink has broad benefit to the genomics community, from genome scaffolding and beyond. ntLink is an open-source project and is freely available from https://github.com/bcgsc/ntLink. © 2023 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol 1: ntLink scaffolding using overlap detection Basic Protocol 2: ntLink scaffolding with gap-filling Basic Protocol 3: Running in-code iterations of ntLink scaffolding Alternate Protocol 1: Generating long-read to contig mappings with ntLink Alternate Protocol 2: Using ntLink mappings for genome assembly correction with Tigmint-long Support Protocol: Installing ntLink.

Comparison of shoulder functions between assembly workers with and without subacromial pain syndrome.

The occurrence of subacromial pain syndrome (SPS) is associated with the frequent handling and lifting of heavy loads and excessive repetitive work. Thus, assembly workers have a high prevalence of SPS. The purpose of this study was to investigate differences in shoulder ROM, muscle strength, asymmetry ratio, function, productivity, and depression between workers with and without SPS. Sixty-seven male workers (35 workers with SPS and 32 workers without SPS) participated in this study. Shoulder internal rotation (SIR), shoulder external rotation (SER), shoulder abduction (SAB), shoulder horizontal adduction ROM and SIR, SER, elbow flexion (EF), scapular depression and adduction, scapular protraction strength were measured. The asymmetry ratio was calculated using the asymmetry ratio formula; shoulder functions were measured using the shoulder pain and disability index (SPADI), disabilities of the arm, shoulder, and hand (DASH), and visual analogue scale (VAS); and Endicott work productivity scale (EWPS). The SPADI (p = 0.001), DASH (p = 0.001), and VAS (p = 0.001) values of workers with SPS were higher than those of workers without SPS. Also, workers with SPS had lower SIR (p = 0.001) and SAB (p = 0.002) ROM compared to workers without SPS. In addition, workers with SPS exhibited lower SIR (p = 0.012) strength than workers without SPS. Workers with SPS had higher asymmetry ratio in SIR (p = 0.015), SER (p = 0.005), and EF (p = 0.008) strength than workers without SPS. The SIR, SAB ROM, SIR strength, and the asymmetry ratio of SIR, SER, EF strengths could provide an important baseline comparison for the workers with SPS.

Justification of the use of multifunctional assembly and welding manipulators at shipyards

This article substantiates the possibility of increasing the level of mechanization of assembly and welding production of shipyards by introducing multifunctional complex mechanized assembly and welding manipulators. The idea is substantiated that such a manipulator, initially having relatively small functionality, but the projected possibility of a gradual increase and complication of functions, can contribute to an increase in the level of mechanization of production, up to its complete robotization. It is concluded that the creation of such equipment already at this stage will increase the flexibility of assembly and welding production, due to readjustability (like a robot) and, most importantly, adaptability to continuous phased modernization, which in the final stage will lead to the creation of a full-fledged industrial robot to perform specific assembly and welding work.

Samsung in Vietnam: FDI, Business–Government Relations, Industrial Parks, and Skills Shortages

AbstractSamsung has largely shifted its electronics manufacturing out of China, and mostly to Vietnam. In that process, it has, to date, avoided local labour market (LLM) difficulties faced by its subsidiaries in industrial parks in China: in particular, pervasive skill shortages among the electronics assembly workers on whom Samsung’s manufacturing depends. Labour retention problems in China had significantly challenged its commitment to invest in necessary employee training. By contrast, Samsung’s domination of foreign direct investment (FDI) within particular Vietnamese industrial parks has removed the inter-employer competition it experienced in China. A deeper explanation involves Samsung’s development – as Vietnam’s largest single source of FDI, and major producer of that country’s exports – of synergistic and symbiotic relationships with Vietnam’s national and subnational governments. These relationships have allowed Samsung to influence development strategies for industrial parks and their LLMs. Samsung has invests expansively in forms of education and training whose benefits extend beyond the areas in which its manufacturing facilities operate, to populations that the company does not employ. Providing benefits beyond typical success criteria for FDI in developing economies, Samsung has helped Vietnam’s party-state meet its own legitimacy needs with its internal constituencies, contributing to a broader practical consensus in favour of the party-state’s development policies. This article therefore widens the perspective of FDI to embed it in national and subnational business–government relations.

New Framework for Complex Assembly Digitalization and Traceability Using Bill of Assembly and Smart Contracts

This paper proposes a framework to automate the generation of traceable and protected documentation of complex assembly processes. The final assembly in aviation, automotive, and appliances industries is a rigorous process that has limited capabilities of full traceability associated with: (1) the parts installed, (2) their fabrication processes, and (3) the assembly work. This is also the case for each of its sub-assemblies. The thousands of parts forming a hierarchy of sub-assemblies that are dynamically accumulated to compose the final assembly make full traceability a challenging feat that is almost unsurmountable. Such full traceability along the entire supply chain requires considerable cost and effort since it must be based on documentation of most assembled parts, assembly tasks, and inspection tasks that compose the full assembled product. In addition, security measures are needed to prevent hostile hacking and unauthorized approach to the assembly documentation throughout the entire supply chain. The related documentation and repeated verifications require considerable effort and have many chances for human errors. So, automating these processes has great value. This article expounds a framework that harnesses blockchain and smart-contract technology to offer automated traceable and protected documentation of the assembly process. For this purpose, we expand the concept of a Bill-Of-Assembly (BOA) to incorporate data from the bill of materials (BOM), the associated assembly activities, the associated activities’ specification parameters and materials, and the associated assembly resources (machines and/or operators). The paper defines the operation of the BOA with blockchain and smart-contract technology, for attaining full traceability, safety, and security, for the entire assembled product. Future research could extend the proposed approach to facilitate the usage of the BOA data structure in constructing a digital twin of the entire simulated system.

Polyplastics introduces DURANEX® 201EB PBT resin for millimeter wave radar for automotive applications

The Polyplastics Group has announced the launch of a new electrically conductive grade of DURANEX® polybutylene terephthalate (PBT) for millimeter wave radar applications for the automotive industry. DURANEX® PBT 201EB reportedly provides the benefit of electromagnetic wave shielding as an added effect of electrical conductivity. As a result, the material should contribute to reduced assembly work and cuts cost.

Formation and manipulation of 2D colloidal crystals driven by convective currents and electrostatic forces

Colloidal crystal plays a major role in novel optical devices such as waveguides, photonic crystals, and colloidal crystal lasers, among others. It has been known that colloidal crystals may self-assemble due to optical, electric, or chemical potentials, and light-induced thermal effects, such as thermophoresis and convective currents. In this work, the formation and manipulation of a self-limiting assembly of monolayer colloidal crystals using a 20 nm absorbing thin film of titanium and a CW-laser emitting at 1070 nm is reported. The colloidal particles, dragged by thermally induced convective currents, self-assembling over the titanium thin film around the laser focal spot. The self-assembled monolayer colloidal crystal tends to form a circular shape. Using numerical simulation, we obtained a potential well associated with the convective currents that spatially govern the radial extension of the monolayer colloidal crystal. We also show, that by changing the pH of the solution i.e., by tuning the electrostatic interaction, the monolayer colloidal crystal can be formed or destroyed. In addition, it was possible to create a larger monolayer colloidal structure covering an area of 600 μm2 using an array of six laser spots.